Lecture Notes Flashcards

Question

What is dry eye disease (DED) caused by?

Answer 1

caused by either a deficiency of tear secretion or excessive evaporation ## Footnote results in tear hyperosmolarity = ocular surface damage and inflammation and chronic symptoms of ocular discomfort with visual loss NOTE: also known as keratoconjunctivitis sicca (KCS)

Answer 2

1. Aqueous-deficient dry eye 2. Evaporative dry eye

Answer 3

1. Inflammatory damage to lacrimal glands by invading lymphocytes 2. Less commonly, congenital lacrimal deficiency, from lymphomatous or sarcoid infiltration of lacrimal gland or secretion by conjunctival scarring in trachoa, Sjogren's or mucous membrane pemphigoid

Answer 4

1. Rheumaroid arthritis 2. SLE 3. PBC 4. Scleroderma

Answer 5

rosacea, seborrheic and atopic dermatitis also: toxic response to the use of 13 cis-retinoic acid in treatment of acne Disorders of lid congruity, aperture and dynamics can also cause EDE, so that it is a possible complication of proptosis, ectropion and Parkinson disease – where blink rate is reduced.

Answer 6

A condition in which delivery of Meibomian oil to the tear film is obstructed by changes in the terminal ducts of the glands and by an increase in viscosity of the delivered lipid. This leads to tear film instability and increased water loss

Answer 7

Meibomian gland dysfunction

Answer 8

1. Clinical findings (reduced lacrimal and salivary function) 2. Presence of raised titres of anti-Rho and anti-La antibodies 3. Demonstration of T-cell infiltration in minor salivary gland biopsy

Answer 9

shows dark spots of early tear film break‐up occur during blink suppression, diagnostically, <5 seconds after the last blink ## Footnote In normal subjects, the stained tear film can remain intact for an extended period in the absence of blinking,

Answer 10

Blink rate is reduced

Answer 11

Tear film instability

Answer 12

characteristic pattern of fluorescent dots over the exposed corneal and conjunctival surface

Answer 13

Oxford grading scale

Answer 14

Peripheral

Answer 15

Responsible for 8% of global blindness & is the no. 1 cause of irreversible blindness in Western society. Glaucoma is the 2nd most common cause of registration of visual impairment in the over 65s (1 st AMD & macular degeneration, 3rd DR).

Answer 16

Made up of retinal ganglion cell axons and follow a specific pattern: Fibres 'close' to fovea & disc (papillomacular bundle) = **linear route** Fibres everywhere else (nasal, superior temporal, inferior temporal) = bypass the papillomacular bundle = **arcuate path**

Answer 17

Anatomical depression in optic nerve head that is not occupied by axons (importance = cup/disc ratio).

Answer 18

The tissue between the border of the cup and the disc Made up of retinal ganglion cells

Answer 19

Colourless, clear fluid for nutrition, structural support & removal of waste products (RE: avascular cornea). Produced by ciliary body (2-3 L/min) through an active process (Na/K ATPase moving ions between pigmented & non-pigmented cells).

Answer 20

Endothelium, which uses transcytosis to transport material across cells. Juxtacanalicular, which uses collagen beams & GAG proteins to slow water.

Answer 21

Glaucoma is a collection of diseases that cause optic neuropathy (damage to the optic nerve head specifically) and produce visual field loss. The condition is often associated with a raised intraocular pressure (IOP > 21), which ranges between 10 - 21 mmHg. However, not always the case (25% of patients will have normal tension glaucoma).

Answer 22

Used when there is at least 1 x clinical feature of the disease, including an elevated lOP, a suspicious optic nerve ("cupping"), abnormal visual field, or a strong family history.

Answer 23

Tags of abnormal mucus that attach to the corneal surface, causing pain due to tugging during blinking.

Answer 24

< 10mm wetting in 5 minutes ## Footnote Occasionally, reflex overproduction of tears due to ocular irritation may confuse the diagnosis.

Answer 25

1. **Low-viscosity cellulose polymers** (prolong the residence time of moisturizing drop and allow inflammatory mediators to be flushed from the ocular surface) 2. **Mild steroids** (suppress inflammation, but must monitor for raised IOP) 3.** Hyaluronic acid** (where inflammation in limited) ## Footnote Other agents are available which are directed towards lubrication, water retention, protection from hyperosmolar damage (osmoprotection), stabilization of the tear film lipid layer and promotion of epithelial cell viability.

Answer 26

* Use regularly throughout the day (not PRN) * Avoid substitutes that contain preservatives (can exacernate the condition)

Answer 27

Their non‐Newtonian property (less viscous when moving, more viscous when stationary) allows them to be formulated at relatively high viscosity, which extends their retention time, while they ‘shear thin’ during the blink or saccade, avoiding intolerance due to frictional drag.

Answer 28

topical cyclosporin A, tacrolimus and lifitegrast, which inhibit the migration of activated lymphocytes to the ocular surface

Answer 29

It may be necessary to occlude the puncta with plugs, or more permanently with surgery, to conserve the tears

Answer 30

the main goal should be to reduce lid margin inflammation and restore the Meibomian contribution to the tear film lipid layer. Treatment is designed to achieve a more efficient control of the tear film stability, applying heat and massage to the lids, antibiotic drops or ointment and systemic antibiotics where necessary

Answer 31

Correction of lid deformity is required

Answer 32

A temporary ptosis can be induced with a local injection of botulinum toxin into the levator muscle to effect a short‐term paralysis and lowering of the upper lid. A more permanent result can be obtained by suturing together part of the apposed margins of the upper and lower lids to reduce the palpebral aperture (e.g. lateral tarsorrhaphy), or the use of gold/platinum weights inserted into the lids to assist closure.

Answer 33

Goblet cells

Answer 34

A symblepharon is a partial or complete adhesion of the palpebral conjunctiva of the eyelid to the bulbar conjunctiva of the eyeball.

Answer 35

Vitamin A deficiency (xerophthalmia) is a condition causing childhood blindness on a worldwide scale. It is associated with generalized malnutrition in countries such as India and Pakistan. **Goblet cells are lost from the conjunctiva and the ocular surface becomes keratinized (xerosis). **An aqueous deficiency may also occur. A characteristic corneal melting and perforation which occurs in this condition (**keratomalacia**) may be prevented by early treatment with vitamin A.

Answer 36

excessive tearing caused by excessive tear production or secondary to poor drainage

Answer 37

The tear drainage system may become blocked at any point, such as the puncta or canaliculi, but the most common site is the **nasolacrimal duct.** Causes include infections or direct trauma to the nasolacrimal system and, occasionally, topically applied drugs.

Answer 38

special radiographic test to see if there is blockage of the tear canals A more physiological test follows the passage of a drop of technetium isotope instilled into the lateral conjunctival sac, through the drainage system, using a gamma camera (dacryoscintigram)

Answer 39

describes the creation of a functional pathway from the canaliculi into the nose by means of creating an osteotomy and opening the nasolacrimal sac into the nose.

Answer 40

DCR (dacryocystorhinostomy)

Answer 41

Keratitis Uveitis Acute glaucoma

Answer 42

Lymphoid collection with its own germinal centre ## Footnote Implies viral or chlamydial infections, or sometimes toxic reaction to topical medication.

Answer 43

Deposits of inflammatory cells on the corneal endothelium. Neutrophils are responsible for fine KPs and lymphocytes or macrophages for coarse, or 'mutton fat' KPs.

Answer 44

Chronic keratitis may stimulate the peripheral ingrowth of subepithelial blood vessels = pannus

Answer 45

Neisseria gonorrhoae ## Footnote Systemic complications include rhinitis, stomatitis, arthritis, meningitis and septicaemia. Patients should be managed with the help of a paediatrician. Due to increasing resistance to penicillin, a systemic, third‐generation cephalosporin (ceftriaxone (or cefotaxime) given im or iv) is used to treat the condition. The eye must be kept clean with 0.9% saline irrigation. Topical bacitracin ointment can also be given but systemic treatment is the most important. Parents should be referred to a sexually transmitted diseases (STD) clinic.

Answer 46

chlamydial serotypes D-K

Answer 47

Patients present with a mucopurulent follicular conjunctivitis and develop a micropannus (superficial peripheral corneal vascularization) associated with subepithelial scarring. Urethritis or cervicitis is common.

Answer 48

Inclusion conjunctivitis is treated with systemic tetracycline because of the likelihood of genital tract infection. Other systemic agents in use include doxycycline and erythromycin, and azithromycin may be given as a single dose. The patient should be referred to an STD clinic.

Answer 49

chlamydial serotypes A-C

Answer 50

**Subconjunctival fibrosis** caused by frequent re-infections associated with the unhygienic conditions Blindness may occur due to corneal scarring from recurrent keratitis and trichiasis

Answer 51

Trachoma is treated with oral or topical tetracycline or erythromycin. Azithromycin, an alternative, requires only a single oral dose. Entropion and trichiasis require surgical correction.

Answer 52

recurrent, bilateral allergic inflammation of the conjunctiva

Answer 53

Initial therapy is with mast cell stabilizers (e.g. sodium cromoglycate, nedocromil, lodoxamide) and antihistamines (e.g. levocabastine), or with agents combining mast cell stabilizing and antihistamine properties (e.g. olopatidine). Topical steroids are required in severe cases but long-term use is avoided if possible because of the risks of steroid-induced glaucoma or cataract. In such cases, topical cyclosporine or tacrolimus may be used. Mucolytics (acetylcysteine) may be required to help dissolve the corneal plaque but surgical removal may be necessary.

Answer 54

inflammatory condition of the upper tarsal conjunctiva, presenting with hyperaemia and roughness of the conjunctival surface in response to contact lens use

Answer 55

small, yellowish, paralimbal lesions in the horizontal meridian that are unassociated with irritation and never impinge on the cornea.

Answer 56

Pterygia are wing-shaped elevations of the interpalpebral conjunctiva, usually bilateral, and located nasally. The apex of the pterygium is directed towards the cornea, onto which it progressively extends with time.

Answer 57

Topical steroids must not be given to patients with a dendritic ulcer, since they may exacerbate the disease and cause extensive corneal ulceration.

Answer 58

a deeper, disc-shaped, localized area of secondary corneal stromal edema and haze accompanied by anterior uveitis immunogenic reaction to herpes (HSV) antigen in the strome

Answer 59

Oral antiviral treatment given for seven days (e.g. aciclovir, famciclovir) is effective in reducing post‐infective neuralgia (a severe chronic pain in the area of the rash) if given within 3 days of the eruption of skin vesicles. Ocular disease may require antibacterials to prevent secondary infection. Steroid use is controversial.

Answer 60

Cyanoacrylate glue

Answer 61

Topical chlorhexidine, polyhexamethylene biguanide (PHMB) and propamidine are used to treat the condition. Prolonged treatment over a period of several months is often needed.

Answer 62

Liquid and solid **Sabouraud media** are used to grow the fungi, often requiring prolonged incubation.

Answer 63

The whitish inflammatory stromal infiltrate of fungal keratitis may be difficult to distinguish from that of bacterial keratitis, but the presence of satellite lesions outside the main lesion may be an important clue to diagnosis.

Answer 64

This term is used for any vascular keratitis that affects the corneal stroma without epithelial involvement. In the past, the most common cause was congenital syphilis, leaving a midstromal scar interlaced with the empty ('ghost') blood vessels. Corneal grafting may be required when the opacity is marked and visual acuity reduced.

Answer 65

Anterior Stromal Posterior

Answer 66

Anterior dystrophies involving the epithelium. These may present with painful attacks as in inherited recurrent corneal erosion. In Meesmann dystrophy, tiny microcysts are scattered throughout the epithelium. Both are dominantly inherited.

Answer 67

Stromal dystrophies presenting with visual loss. If very anterior, they may also cause corneal erosion and pain. Examples are granular corneal dystrophy (dominant trait) and macular dystrophy (recessive trait).

Answer 68

Posterior dystrophies which affect the endothelium occur in congenital and adult forms. Loss of endothelial pumping results in corneal oedema which leads to a gradual loss of vision. An example is Fuchs dystrophy, which may present in middle to late adult life. It may be a sporadic condition or be inherited as a dominant trait. An X-linked form of endothelial dystrophy exists. The clinical features of Fuchs dystrophy are identical to those seen in other forms of endothelial failure.

Answer 69

a painless disorder, usually sporadic but sometimes inherited, in which progressive central corneal thinning leads to an ectatic conical shape and marked myopia and astigmatism.

Answer 70

The condition is due to a failure of cohesion between the stromal collagen fibrils and lamellae of unknown cause, causing them to slip over one another and unravel. This leads to stromal thinning and ectasia. Thinning may be pronounced, but rarely leads to perforation.

Answer 71

Early stages = rigid contact lenses that arch over the irregularly shaped cornea Late/Advanced stages = surgical intervention (penetrating keratoplasty - replacement of the central cornea with a full thickness corneal allograft) More recently, using lamellar techniques, it has been possible to replace the corneal stroma alone, leaving the healthy endothelium intact.

Answer 72

to transfer water from the corneal stroma to the anterior chamber and thus maintain a miminum corneal thickness This ensures the regular order and separation of the stromal collagen fibrils that is necessary for corneal transparency

Answer 73

By cell spreading (which entails an enlargement of cells and fall in cell density)

Answer 74

Loss of barrier and pumping functions occurs -> stromal oedema and clouding as the regular packing of the collagen fibres is disrupted This may be detected at an early stage as an increase in corneal thickness or inferred by the presence of punctate excrescences in Descemet layer of the cornea (corneal guttae).

Answer 75

Collections of abnormal basil laminar material synthesized by the sick endothelial cells

Answer 76

Causes of endothelial cell damage include uveitis, cataract surgery, corneal graft failure and, as noted earlier, inherited endothelial disease (Fuchs dystrophy).

Answer 77

Endothelial failure Treatment = endothelial keratoplasty

Answer 78

Subepithelial deposition of calcium phosphate in the exposed part of the cornea where CO2 loss and the consequent raised pH favour its deposition Seen in patients with chronic uveitis or glaucoma

Answer 79

If symptomatic, it can be scraped off surgically, aided by a chelating agent such as sodium edetate to remove the calcium at the time of surgery.

Answer 80

Systemic hypercalcaemia (as in hyperparathyroidism or renal failure) The lesion is then more likely to occupy the 3 o'clock and 9 o'clock positions of the paralimbal cornea. James, Bruce; Bron, Anthony; Parulekar, Manoj V.. Ophthalmology: Lecture Notes (p. 296). Wiley. Kindle Edition.

Answer 81

Rare cause of painful peripheral corneal thinning - it is a condition of progressive corneal melting with an immune basis, which starts near the limbus and spreads relentlessly across the cornea.

Answer 82

ACAID provides a distinct immunological privilege to the eye. The regulation of inflammatory processes by ACAID leads to protection from potentially blinding inflammatory processes. ACAID suppresses CD4, Th1/2, and B cells

Answer 83

Up to 90% of such first‐time keratoplasties in avascular corneas succeed without HLA cross‐matching and with only the use of topical corticosteroid drops to prevent rejection. ## Footnote The reason for this difference is that the cornea is the site of an immune privilege which protects the graft from rejection.

Answer 84

Graft survival is much lower when the host cornea is heavily vascularized, probably in part because the cornea is also richly provided with lymphatics which undermine the graft's immune privilege. Although tissue can be HLA‐matched for the grafting of vascularized corneas at high risk of rejection, the value of this is still uncertain.

Answer 85

DSEK (Descemet stripping endothelial keratoplasty) DMEK (Descemet Membrane Endothelial Keratoplasty). ## Footnote The graft used in DSEK incorporates a thin layer of the donor stroma, DMEK allows an even thinner graft to be used with no stroma. DALK (Deep Anterior Lamellar Keratoplasty) involves replacing the corneal epithelium and stroma without disturbance of the endothelium, minimizing the risk of rejection.

Answer 86

Redness, pain or visual loss = must be seen urgently by an eye specialist, as this may indicate graft rejection. Examination shows graft oedema, iritis and a line of activated T-cells attacking the graft endothelium. ## Footnote Intensive topical steroid application in the early stages can restore graft clarity.

Answer 87

SCLERITIS It is an emergency (sight-threatening condition).

Answer 88

Anterior necrotizing scleritis without inflammation, so called scleromalacia perforans, is a rare, severe eye disorder developing an autoimmune damage of episcleral and scleral performing vessels (hypersensitivity type III) Associated with rheumatoid arthritis.

Answer 89

choroidal effusions, or may simulate a tumour

Answer 90

Nuclear, cortical or subcapsular

Answer 91

Crystallins - the major lens proteins, undergo cross‐linking and the formation of molecular aggregates of sufficient size to scatter light. Results in **brown** products. Colour perception and contrast sensitivity may be altered but, initially, visual acuity may not be greatly affected. The hardness conferred to the lens nucleus by protein cross‐linking may create problems when performing lens fragmentation during phacoemulsification surgery.

Answer 92

This form of cataract is due to a breakdown of groups of fibres in the lens cortex. Because these fibres are radially arranged in a pattern that relates to depth and clock position, the affected zones have a radial, spoke-like appearance and may be peripheral or extend more centrally. Peripheral spoke opacities have no effect on vision but those that encroach upon the visual axis will do so and may require action if symptomatic.

Answer 93

Posterior subcapsular cataract may arise acutely following blunt injury to the eye or after vitreous surgery (vitrectomy), or it may evolve slowly after X-radiation to the orbit and with steroid treatment.

Answer 94

Pseudophakic

Answer 95

Short course of steroid and antibiotic drops Can get new glasses (if needed) after a few weeks

Answer 96

1. Vitreous loss 2. Iris prolapse 3. Endophthalmitis 4. Cystoid macular oedema 5. Retinal detachment 6. Opacification of the posterior capsule

Answer 97

If the posterior capsule is accidentally torn during the operation, the vitreous gel may prolapse forward into the anterior chamber, where it represents a risk for glaucoma by obstructing aqueous outflow via the trabecular meshwork. Prolapsed gel may also cause retinal traction and increase the risk of retinal detachment, and may interfere with placement of the lens implant. The gel requires careful aspiration and excision (vitrectomy) at the time of surgery. Placement of the intraocular lens usually follows during the same procedure, but may need to be deferred to a secondary procedure.

Answer 98

The iris may protrude through the surgical incision in the immediate postoperative period, appearing as a dark elevation at the incision site accompanied by pupil distortion. This requires prompt surgical repair.

Answer 99

Painful red eye Reduced visual acuity Collection of white cells int eh anterior chamber (hypopyon)

Answer 100

This is an extreme ophthalmic emergency. The patient requires urgent sampling of the aqueous and vitreous for microbiological analysis and intravitreal injection of a broad-spectrum antibiotic at the time of sampling (e.g. vancomycin and ceftazidime) to provide immediate cover. Further management is dependent on the microbiological report and clinical response. The use of intravitreal corticosteroids in conjunction with the antimicrobials is debated.

Answer 101

The macula may become oedematous following routine uncomplicated surgery. The risk is greater if surgery was accompanied by vitreous loss or inflammation. It may settle with time but can produce a severe and permanent reduction in acuity. The release of prostaglandin from inflamed intraocular tissues plays an important role and prompt treatment with topical NSAIDs and steroid can alleviate the oedema in a proportion of patients. It may be necessary to inject steroids into or around the eye in resistant cases.

Answer 102

Normally, the thin capsular layer that lies behind the implant is crystal clear. However, in approximately 20% of patients, clarity of the posterior capsule decreases in the months following surgery, when residual epithelial cells migrate across its surface to form an opaque scar. Vision then becomes blurred and there may be problems with glare. This is often referred to as an ‘aftercataract’.

Answer 103

The treatment is YAG laser capsulotomy, using a neodymium yttrium garnet (Nd‐YAG) laser to create a small central opening in the capsule as an outpatient procedure. There is a small risk of cystoid macular oedema or retinal detachment following YAG capsulotomy. Research aimed at reducing capsule opacification has shown that the lens implant material, the shape of the lens edge and overlap of the intraocular lens by a small rim of anterior capsule are important factors in preventing this complication.

Answer 104

bilateral, conical anterior protrusion of the anterior lens surface (**anterior lenticonus**) It is caused by mutations influencing the structure of type IV collagen, a key component of basal laminae within the glomerulus, the Organ of Corti and the lens capsule.

Answer 105

Homocystinuria - displaced downwards Marfan syndrome - displaced upwards

Answer 106

Inflammation of the ciliary body is termed cyclitis, of the pars plana is pars planitis and of the vitreous is vitritis. As a group, these are termed intermediate uveitis.

Answer 107

Inflammation of the posterior uvea is termed posterior uveitis and may involve the choroid (choroiditis), the retina (retinitis) or both (chorioretinitis).

Answer 108

Steroids Anterior = eye drops Posterior = systemic

Answer 109

relieves the pain from ciliary spasm + prevents the formation of posterior synechiae

Answer 110

occur either from direct destruction to the retina and choroid (e.g. in toxoplasmosis or CMV infection) or from fluid accumulation in the layers of the macula (macular oedema)

Answer 111

The principle of a sub-Tenon injection. A cannula is placed in the potential space between the sclera and Tenon capsule. Injection of steroid separates the two layers and the steroid spreads to surround the eye.

Answer 112

Urethritis Arthritis Conjunctivitis

Answer 113

This is a rare, unilateral, chronic uveitis usually presenting in young adults. The cause is uncertain, it may be immunemediated and there are no systemic associations. ## Footnote A mild anterior uveitis is present, but without signs of conjunctival or ciliary injection, and there are no posterior synechiae. There are KPs distributed diffusely over the cornea and there is iris heterochromia, the iris colour of the affected eye being different from that of the fellow eye, due to a loss of epithelial pigment cells. The vitreous may be inflamed and condensations (the cause of the floaters) may be present. About 70% of patients develop cataract. Glaucoma occurs to a lesser extent.

Answer 114

The clinical appearance is usually diagnostic, but a positive anti-toxoplasma antibody test is suggestive. However, a high percentage of the population have positive IgG titres due to prior infection.

Answer 115

a multisystem disorder presenting with a bilateral panuveitis with exudative retinal detachments and followed by neurological and cutaneous manifestations such as alopecia (focal baldness) and loss of lash and skin pigments (poliosis and vitiligo). It is a cell‐mediated autoimmune disease probably directed against tyrosinase‐related proteins, TRP1 and TRP2 contained in melanocytes.

Answer 116

Chronic antiviral therapy with ganciclovir and/or foscarnet

Answer 117

A penetrating or surgical injury to one eye involving the retina may rarely excite a peculiar form of uveitis which involves not only the injured eye but also the fellow eye.

Answer 118

Posterior scleritis Retinal detachment Angle closure glaucoma

Answer 119

Axon loss results in visual field defects and a loss of visual acuity if the central visual field is involved.

Answer 120

into the posterior chamber by the ciliary processes combination of active transport and ultrafiltration

Answer 121

Open-angle glaucoma

Answer 122

angle-closure glaucoma

Answer 123

1. thickening of the trabecular lamellae, which reduces pore size 2. reduction in the number of lining trabecular cells 3. increased extracellular material in the trabecular meshwork spaces.

Answer 124

raised IOP without evidence of visual damage or pathological optic disc cupping

Answer 125

Dim light (pupil more dilated)

Answer 126

Chronic angle-closure glaucoma may also occur, when extensive PAS causes a gradual elevation of intraocular pressure associated with glaucomatous optic nerve head damage, pathological cupping and visual field loss. It may be asymptomatic until significant changes have occurred.

Answer 127

Raised episcleral venous pressure as a cause

Answer 128

myocilin gene (GLC1A) on Chr 1

Answer 129

Measuring the thickness of the cornea

Answer 130

Prostaglandin analogues MoA = increase the passage of aqueous through the uveoscleral pathway

Answer 131

Benzalkonium Chloride (BAK) Acts as a detergent lysing cell membranes and killing bacteria

Answer 132

Fistula created between the anterior chamber and subconjunctival space

Answer 133

1. shallowing of the anterior chamber in the immediate postoperative period risking damage to the lens and cornea 2. intraocular infection 3. possibly accelerated cataract development 4. failure to reduce intraocular pressure adequately 5. scarring causing a longer term rise in IOP 6. an excessively low pressure (hypotony) which may cause macular oedema.

Answer 134

antimetabolite drugs (5-fluorouracil and mitomycin)

Answer 135

IV acetazolamide + topical acetazolamide + topical pilocarpine + beta-blockers

Answer 136

With a Nd-YAG laser or surgically

Answer 137

CYP1BI and LTBP2 genes Autosomal recessive

Answer 138

Enlargement of the globe

Answer 139

enlarged optic CUP

Answer 140

The RPE removes and processes the used discs of the photoreceptor outer segments. Over time, undigested lipid products, such as the age pigment lipofuscin, accumulate in the RPE and the excess material is transferred to Bruch membrane, impairing its diffusional properties. Extracellular deposits form between the RPE and Bruch membrane which can be seen with the ophthalmoscope as discrete, sub-retinal yellow lesions called drüsen.

Answer 141

These are seen classically in the rare recessive disorder pseudoxanthoma elasticum, and uncommonly, in systemic diseases such as Paget disease and sickle cell disease. Again, there may be a profound reduction in central vision. Vision is also reduced if the crack itself passes through the fovea.

Answer 142

a localized accumulation of fluid between the neuroretina and the RPE separates the two layers and disturbs the photoreceptor layer ## Footnote It results from a localized breakdown in the normal barrier function of the RPE.

Answer 143

**Steroids** in high doses (oral or periocular injection) are helpful in macular oedema caused by uveitis; **acetazolamide** may be helpful in treating patients with macular oedema accompanying retinitis pigmentosa or occurring following intraocular surgery. **Non-steroidal anti-inflammatory drops** may also have a role in preventing and treating cystoid macular oedema associated with intraocular surgery.

Answer 144

Toxic maculpathy ## Footnote The maculopathy is initially only detected by accurate assessment of macular function. At this early stage, discontinuation of the drug reverses the maculopathy. Later, a pigmentary, ‘target lesion’ is seen ophthalmoscopically, associated with metamorphopsia and an appreciable and irreversible loss of central vision.

Answer 145

Ocular toxicity is unlikely with a dose of less than 4 mg (chloroquine phosphate) per kg lean body weight per day or a total cumulative dose of less than 300 g. The screening of patients on hydroxychloroquine at the recommended dose is also advised annually after 5 years of treatment or sooner if higher doses (>5 mg/kg/day) of the drug are used.

Answer 146

With ageing, the vitreous gel undergoes degenerative changes (earlier in myopes) with liquefaction and the formation of fragments of condensed vitreous. These cast shadows on the retina, giving rise to the common symptom of vitreous 'floaters'. Subjectively, these take the form of spots or cobwebs which obscure vision only slightly and move when the eyes move, reflecting the fluid nature of the vitreous. Symptoms are most marked on bright days, when the small pupil throws a sharper image on the retina.

Answer 147

Neuroretina + pigment epithelium (there is a potential space between them)

Answer 148

1. rhegmatogenous (due to tear or hole) 2. tractional (due to contracting fibrous tissue) 3. exudative (fluid accumulates due to exudative precess e.g. in pregnancy-induced HTN or retinal tumours)

Answer 149

The onset of a posterior vitreous detachment An underlying peripheral weakness of the retina e.g. lattice degeneration increases tear probability

Answer 150

An operculated tear results from vitreous traction that pulls a plug of sensory retina out into the vitreous cavity.

Answer 151

Retinal tears unassociated with sub-retinal fluid are treated prophylactically with a laser or cryoprobe to induce inflammation and increase the adhesion between the neuroretina surrounding the tear and the pigment epithelium, thus preventing a retinal detachment. It is always important to check the peripheral retina in the fellow eye, as tears or an asymptomatic retinal detachment may be present here too.

Answer 152

Usher syndrome, abetalipoproteinaemia and Laurence-Moon syndrome.

Answer 153

In retinoschisis, the retina splits into an inner and outer leaf at the outer plexiform and inner nuclear junction. It is usually seen in the lower temporal quadrant of the retina and is often bilateral. The appearance is not dissimilar to a retinal detachment. Rarely, it may cause a retinal detachment when there are holes in both the inner and outer retinal leaves. These patients may require surgery.

Answer 154

1. peripheral clumps of retinal pigmentation (termed 'bone spicule' pigmentation); 2. attenuation of the retinal arterioles; 3. disc pallor - optic atrophy. ## Footnote Patients may also have cataracts at an early age and may develop macular oedema.

Answer 155

This is less common than retinitis pigmentosa. It is usually autosomal dominant, but many cases are sporadic. Patients present in the first decade of life with poor vision. Examination reveals an abnormal, banded macular appearance which has been likened to a bull'seye target. No treatment is possible but it is important to provide appropriate help, not only to maximize vision but also to help with educational problems. Genetic counselling should be offered.

Answer 156

a tumour suppressor gene whose product (pRB) plays a key role in the cell cycle as a negative regulator of cell proliferation. Mutations remove this anti-proliferative action, and predispose to cancer formation. ## Footnote In somatic cases (60% of all cases), a single retinal cell loses one normal allele of the Rb1 gene during retinal development. Loss of the second normal allele results in disease which is always unilateral. Somatic cases cannot transmit disease to offspring. In germline cases (40% of all cases), one copy of the Rb1 gene is defective (mutated) at the time of conception from a defective sperm or ovum, and every cell in the body has the defective gene. This can occur as a random event with unaffected parents (sporadic), or either parent might have undergone treatment for retinoblastoma and carry the defective gene, which is passed on to the offspring (inherited) in 50% of cases (autosomal dominant inheritance - see Chapter 2). Such cases can have unilateral or bilateral disease often with multiple tumours. They can genetically transmit the disease to their offspring and are also at risk of developing non-ocular second cancers (50% lifetime risk).

Answer 157

patients with certain dominantly inherited systemic disorders: * tuberous sclerosis * neurofibromatosis (less commonly).

Answer 158

They appear as white mulberry-like lesions, are seldom symptomatic and require no treatment. However, their identification may assist in the diagnosis of these important systemic diseases.

Answer 159

Distorsion of vision

Answer 160

AMD results in loss of acuity but never total loss of vision.

Answer 161

Poor night vision

Answer 162

They occur at the margins of an ischaemic retinal infarct due to obstruction of axoplasmic flow and a build-up of axonal debris in the nerve fibre layer of the retina. ## Footnote Their visibility depends on nerve fibre layer thickness at that site, so that they are readily seen close to the optic disc, where the nerve fibre layer is thick but not in the periphery, where the nerve fibre layer is thin. They are white in colour because the accumulated axoplasmic particles scatter light, whereas the normal nerve fibre is transparent.

Answer 163

1. fibrin-platelet emboli (from carotids) 2. cholesterol emboli (from carotids) 3. calcific emboli (from heart valves)

Answer 164

Fibrin–platelet emboli typically cause a fleeting loss of vision as the emboli pass through the retinal circulation (amaurosis fugax).

Answer 165

Aimed at dilating the arteriole to allow the embolus to pass more distally and limit the damage (usually not very successful)

Answer 166

* abnormality of the blood itself (the hyperviscosity syndromes and abnormalities in coagulation); * an abnormality of the venous wall (inflammation); * an increased ocular pressure;

Answer 167

Paradoxically, the incidence of retinal neovascularization is greater in CRVO than CRAO, even though the ischaemia is partial in CRVO and more complete in CRAO. This is because the partially ischaemic, functioning retina following CRVO produces more angiogenic factors such as VEGF than a completely ischaemic retina seen in CRAO.

Answer 168

If the retinal is ischaemia - retinal laster treatment If macular oedema present - anti-VEGF agents

Answer 169

There is an initial failure of normal retinal vascularization, followed by a phase of aggressive new vessel formation extending forward into the vitreous and causing traction detachment.

Answer 170

Patients with sickle-cell haemoglobin C disease (SC disease) and sickle-cell haemoglobin with thalassaemia (SThal) develop a severe form of retinopathy.

Answer 171

A lesion of the optic nerve on one side blocks the afferent limb of the pupillary light reflex. The pupils are equal and of normal size, but the pupillary response to light directed to the affected side is reduced, while the near reflex is intact. Testing for an RAPD is critical in a patient suspected of having an optic nerve lesion, such as optic neuritis. An RAPD may be seen with extensive retinal disease but not with opacities of the cornea or lens.

Answer 172

The key feature is an impaired reaction of the pupils to light, while the near response to accommodation is retained. It is seen with Adie tonic pupil, the Argyll Robertson pupil and with periaqueductal brainstem lesions such as Parinaud syndrome. Other causes include diabetes and multiple sclerosis. There is no condition in which the light reflex is intact but the near reflex is defective.

Answer 173

It is due to a ciliary ganglionitis which denervates the parasympathetic supply to the iris and ciliary body. On recovery from the ganglionitis, reinnervation is incomplete and the partially denervated receptors of the iris and ciliary body become supersensitive to muscarinic stimulation.

Answer 174

The pupils are bilaterally small and irregular. They do not react to light but respond to accommodation. The iris stroma has a typical feathery appearance and loses its architectural detail. Classically, it is seen in neurosyphilis. It is suggested that a periaqueductal lesion on the dorsal aspect of the Edinger Westphäl nucleus involves fibres associated with the response to light, but spares those associated with the near response.

Answer 175

Lesions affecting the pretectal nuclear complex in the dorsal region of the midbrain can disrupt retinotectal fibres while preserving the supranuclear accommodative pathway. This produces mydriasis and a light-near dissociation. Causes include demyelination, infarction, enlargement of the third ventricle and space-occupying tumours such as pinealoma, as part of a dorsal midbrain (Parinaud) syndrome.

Answer 176

In coma, both pupils may become miosed if a pontine lesion is present. The light reflex is preserved but difficult to demonstrate with a small pupil. Remember that patients taking pilocarpine for glaucoma or receiving morphine also show bilateral miosis.

Answer 177

Coma associated with a unilateral expanding supratentorial mass, for example a haematoma, results in pressure on the third nerve and dilation of the pupil. Intrinsic third nerve lesions also cause a dilated pupil

Answer 178

During development, myelination of the optic nerve begins proximally and spreads centrifugally, to be completed at the lamina cribrosa at term.

Answer 179

Optic disc drüsen, which are accumulations of proteinaceous amyloid material within the optic nerve head, can also result in a swollen‐looking optic disc.

Answer 180

In myopia, it is common to see a pale 'myopic crescent' of peripapillary choroidal atrophy at the temporal margin of the optic disc, allowing the overlying, white sclera to show through. In high myopia, the optic disc may be surrounded by such an atrophic area (peripapillary atrophy), which may be confused with disc swelling.

Answer 181

In the short term there is no visual loss. However, in some patients with advanced papilloedema, a fleeting visual loss may occur, lasting seconds, when posture is altered from lying to standing (transient visual obscurations). Visual loss (reduced acuity and significant contraction of the visual fields) can occur with chronic papilloedema.

Answer 182

The central retinal vein is exposed to cerebrospinal fluid (CSF) in the subarachnoid space of the optic nerve as it leaves to join the veins of the orbit. Normally, venous pressure in the retinal veins at the nerve head is just above ocular pressure. Venous pulsation occurs because the vein collapses briefly with each rise in ocular pressure caused by arterial inflow during systole. When the CSF pressure is higher than the ocular pressure, as occurs in papilloedema due to raised ICP, the pressure in the veins at the disc rises above the ocular pressure and spontaneous venous pulsation is lost. Absence of spontaneous venous pulsation is seen in 5–20% of those with normal nerve heads, but in this case, venous collapse at the nerve head can be induced by light pressure on the globe through the lids.

Answer 183

Inflammation or demyelination of the optic nerve results in optic neuritis. This is termed **papillitis** if the optic nerve head is visibly affected and **retrobulbar neuritis** if the optic nerve is affected more posteriorly, with no visible disc swelling.

Answer 184

Neuromyelitis optica (NMO) This is an AI condition where the spinal cord and optic nerves become inflammed

Answer 185

anti MOG antibodies and aquaporin 4 antibodies

Answer 186

The anterior optic nerve may become ischaemic if the posterior ciliary vessels are compromised as a result of degenerative vaso-occlusive or vasculitic disease of the arterioles. The resulting disc swelling is due to an anterior ischaemic optic neuropathy.

Answer 187

The patient complains of a sudden loss of vision or visual field, often on waking, since the blood pressure falls and vascular perfusion of the eye decreases during sleep. If accompanied by pain or scalp tenderness, the diagnosis of giant cell arteritis must carefully be considered. Ischaemic optic neuropathy is the usual cause of blindness in that disease.

Answer 188

## Footnote Vestibular, Saccade and smooth pursuit pathways shown for the right eye only.

Answer 189

where the angle of deviation remains constant in all directions of gaze and the range of eye movements of both eyes are full. This is the common squint seen in childhood.

Answer 190

Where the angle of deviation changes with gaze. This could be due to: * underaction of one or more of the eye muscles due to a nerve palsy (paralytic or paretic squint) or muscular weakness (myogenic squint) as in myasthenia gravis; * mechanical restriction of the muscles ‐ resulting from entrapment of muscles (after orbital fracture), muscle infiltration or scarring (in thyroid eye disease) or an orbital mass. For a nerve palsy, the squint is greatest in the field

Answer 191

For a nerve palsy, the squint is greatest in the field of action of the affected muscle (i.e. the direction in which that muscle would normally take the globe), while with mechanical restriction, the squint is greatest in the direction away from the affected muscle.

Answer 192

In gaze palsies, there is a disturbance of the supranuclear coordination of eye movements. Pursuit and saccadic eye movements may also be affected if the cortical pathways to the nuclei controlling eye movements are interrupted.

Answer 193

Epicanthus (a crescentic fold of skin on the side of the nose that incompletely covers the inner canthus) or telecanthus (increased distance between the inner canthi), which may simulate a convergent squint.

Answer 194

A latent squint (phoria) is a tendency of the eyes to lose binocular fixation, so that they drift apart when they are visually dissociated e.g. in the absence of bifoveal visual stimulation by the same object of regard. It is not necessarily an abnormal condition and small phorias can be demonstrated in most people who otherwise have normal binocular single vision. In general, an esophoria (a tendency of the eyes to drift inwards) is most common in people with hypermetropia and an exophoria (a tendency of the eyes to drift outwards) in those with myopia.

Answer 195

A manifest squint (tropia) on the other hand occurs even when both eyes are open and being simultaneously stimulated. One eye is fixing, and the other eye deviating. Tropias appear spontaneously without the need to dissociate the two eyes. Tropias can be constant, or intermittent with variable control.

Answer 196

Refractive error is measured following topical administration of cyclopentolate eye drops to paralyse accommodation and dilate the pupil. The eye is then examined to exclude opacities of the cornea, lens or vitreous and abnormalities of the retina or optic disc.

Answer 197

A convergent squint develops because of the increased accommodative effort required to focus, particularly on near objects. The link (synkinesis) between the accommodative and convergence mechanisms leads to an excessive convergence and ultimately to a convergent squint of one eye. Where the squint only occurs on attempted focusing on near objects (an accommodative squint), amblyopia does not develop since binocular visual alignment remains normal for part of the time, during distant viewing.

Answer 198

F(a) Recession. The conjunctiva has been incised to expose the medial rectus muscle. The muscle is then disinserted and moved backwards on the globe. (b) Resection. Following exposure of the muscle, the anterior tendon and muscle are resected, thus shortening them; the muscle is then reattached to its original position.

Answer 199

Incomitant squints can be **paralytic** (due to nerve palsy) or **myogenic** (due to muscle weakness, or tight or trapped muscles which restrict eye movement).

Answer 200

infiltration of the extraocular muscles with lymphocytes and the deposition of glycosaminoglycans in the tissues, leading to proptosis, exposure of the globes and limitation of eye movements

Answer 201

Inferior rectusThe inferior rectus is the most commonly affected muscle. Its movement becomes restricted and there is mechanical limitation of the eye in upgaze, which also aggravates the upper lid retraction. Involvement of the medial rectus causes mechanical limitation of abduction, thereby mimicking a sixth nerve palsy. A CT or an MRI scan shows enlargement of the rectus muscles.

Answer 202

1. Excessive exposure of the conjunctiva and cornea with the **formation of chemosis** (oedematous swelling of the conjunctiva), and corneal ulcers due to exposure and failure of the lids to protect the cornea. The condition may lead to corneal perforation. 2. **Compressive optic neuropathy** due to compression and ischaemia of the optic nerve by the thickened muscles. This leads to field loss and may cause blindness.

Answer 203

Patients are treated, in collaboration with a neurologist, with oral pyridostigmine. Systemic steroids, other immunosuppressive agents, and surgical removal of the thymus also have a role in treatment.

Answer 204

This inflammation of the extraocular muscles is associated with pain and diplopia, leading to a restriction in the movement of the involved muscle (similar to that seen in dysthyroid eye disease). It is not usually associated with systemic disease, but thyroid abnormalities should be excluded. The conjunctiva over the involved muscle is inflamed. CT or MRI scanning shows thickening of the muscle. If symptoms are troublesome, it responds to a short course of steroids.

Answer 205

CPEO is a rare condition where the movement of the eyes is slowly reduced bilaterally, often symmetrically. It is caused by a mitochondrial DNA mutation affecting muscle function. There is an associated ptosis. Ultimately, eye movement may be lost completely. There may be accompanying retinal dystrophy and heart block.

Answer 206

In this condition, elevation of the eye in adduction is restricted due to restriction of the superior oblique muscle. The superior oblique muscle tendon fails to pass smoothly through its trochlear pulley or there is a stiff, inelastic tendon-muscle complex. The exact cause remains unknown. The condition may be congenital or result from orbital trauma or inflammation.

Answer 207

This is due to a 'congenital miswiring' or **faulty innervation of the medial and lateral rectus muscles**. The sixth nerve and/or nucleus may rarely be absent. The lateral rectus receives reduced or absent innervation from the sixth nerve. This is often accompanied by aberrant innervation of the lateral rectus by the third nerve. There is therefore reduced activity of the lateral rectus during attempted abduction, and co-contraction of the medial and lateral rectus during adduction. This results in narrowing of the palpebral aperture on adduction, with retraction of the eye into the orbit (due to simultaneous contraction of medial and lateral rectus muscles). The condition may be unilateral or, more rarely, bilateral. ## Footnote Children do not usually develop amblyopia, because the eyes are aligned in the straight ahead (primary) position, or with a small abnormal head posture (face turn away from the affected lateral rectus). Rarely, surgical intervention is needed if there is a squint or if there is a significant abnormal head posture.

Answer 208

Gaze is the coordinated movement of the two eyes together, in a given direction, as in right, left, up or downgaze. It is under the control of supranuclear pathways.

Answer 209

Controls horizontal movements of the eyes ## Footnote Lesions affecting the PPRF are usually associated with other brainstem disease. It may be seen in patients with vascular disease and tumours. James, Bruce; Bron, Anthony; Parulekar, Manoj V.. Ophthalmology: Lecture Notes (p. 559). Wiley. Kindle Edition.

Answer 210

Other brainstem disease ## Footnote It may be seen in patients with vascular disease and tumours. There is a failure of horizontal movements of both eyes to the side of the lesion (a horizontal gaze palsy), and deviation of the eyes to the contralateral side in acute cases.

Answer 211

medial longitudinal fasciculus (MLF)

Answer 212

The MLF connects the sixth nerve nucleus to the third nerve nucleus on the opposite side and coordinates their activity in horizontal gaze movements.

Answer 213

It may be affected by demyelination (e.g. multiple sclerosis - usually bilateral) and vascular disease (unilateral).

Answer 214

The patient complains of horizontal diplopia. There is reduction of adduction on the same side as the lesion, and nystagmus of the contralateral, abducting eye (abducting nystagmus).

Answer 215

In Parinaud syndrome, a lesion in the dorsal midbrain affects the centre for vertical gaze. It may be seen in patients with demyelination, space-occupying lesions such as a pinealoma which presses on the tectum, infarction of the dorsal midbrain or an enlarged third ventricle from hydrocephalus. ## Footnote Also known as dorsal midbrain syndrome.

Answer 216

The disorder causes deficient (and often painful or uncomfortable) elevation of both eyes, convergence of the eyes and retraction into the orbit associated with nystagmus on attempted elevation (convergence-retraction nystagmus) and lightnear dissociation of the pupil (the pupil reacts poorly to a light stimulus but constricts normally on accommodation).

Answer 217

Brainstem disease ## Footnote It may also be seen in toxic states, for example following excess alcohol intake.

Answer 218

Posterior fossa lesion near the cervicomedullary junction (e.g. a Chiari malformation, where cerebellar tissue is dragged through the foramen magnum). It may also be seen in patients with demyelination, and again may be present in toxic states.

Answer 219

a defect in the central control mechanisms of eye movements (congenital idiopathic motor nystagmus) conditions that interfere with visual development within the first few months of life (when steady fixation develops) - for example, bilateral congenital cataracts or glaucoma albinism - the exact mechanism is not understood but may relate to a failure of visual development.

Answer 220

If the orbital rim is intact and the following signs are present: * emphysema * patch of paraesthesia below the rim (infraorbital nerve damage) * limitation of eye movement (esp upgaze and downgaze * eye may become recessed into the orbit (enophthalmos) * lid margin cut at the medial canthus - epiphora

Answer 221

a complication due to a magnetic intraocular or intraorbital foreign body ## Footnote Retained, iron-containing foreign bodies may have an insidious and particularly devastating effect on the eye (siderosis oculi). A tiny, high-velocity metal fragment, penetrating the ocular coats and retained in the peripheral vitreous cavity, can, with time, lead to a progressive, pigmentary degeneration of the retina. The mechanism of damage is by the diffusion of ferrous ions throughout the globe and the generation of free radicals in affected tissues, via the Fenton reaction. A discolouration of the iris (heterochromia), a dilated and unresponsive pupil (fixed mydriasis) and cataract are late clues to the diagnosis. Failure to detect and remove such a foreign body at the time of injury results in irreversible blindness.

Answer 222

After chemical injury, the conjunctiva may appear white and ischaemic. Extensive changes to the corneal limbus, the site of the epithelial corneal stem cells, grossly impair corneal healing by retarding epithelial resurfacing. Additional complications such as uveitis, secondary glaucoma and cataract contribute to the overall burden of disease.

Answer 223

Electromagnetic radiation may injure the conjunctiva and the cornea. Unprotected exposure to ultraviolet radiation from an artificial source (such as an arc lamp (arc eye) or sunlamp), or a natural source (reflected from snow (snow blindness) or water), is the commonest cause of this painful condition. Typically, severe ocular pain starts acutely, 6 hours after exposure to the radiation, and the cornea shows diffuse epithelial oedema and punctate keratitis which resolve within 24-48 hours.

Answer 224

Rupture of blood vessels at the root of the iris

Answer 225

fluttering of the iris diaphragm on eye movement - may suggest dislocation of the lens following blunt trauma

Answer 226

traumatic retinopathy secondary to direct or indirect trauma to the globe.

Answer 227

a separation of the peripheral retina from its junction with the pars plana of the ciliary body

Answer 228

A cyclodialysis cleft is a separation of the ciliary body from the scleral spur, creating a direct connection between the anterior chamber and the suprachoroidal space. ## Footnote Many will spontaneously close, but those that do not can cause chronic hypotony, resulting in hypotony maculopathy, optic disc edema, and decreased visual acuity. Treatment begins with conservative medical therapy, but when this fails, a wide range of laser and surgical procedures have been reported to be effective.

Answer 229

This results from a glancing blunt injury which shears a patch of corneal epithelium from the basal lamina. It is extremely painful, but normally heals in a few days, depending on its size of the epithelial defect. It is treated with antibiotic ointment, with or without an eye pad. Dilatation of the pupil with cyclopentolate 1% can help to relieve pain caused by spasm of the ciliary muscle.

Answer 230

Recurrent corneal erosion is a condition of repeated painful attacks of corneal epithelial detachment, following a non-lacerating corneal injury. Recurrent attacks of extreme, debilitating pain cause marked epiphora and temporary visual loss. The detached epithelium may remain intact, but loose, or be sheared by an extensive erosion. Painful symptoms, persisting for days or weeks, are followed by periods of quiescence. ## Footnote Despite adequate epithelial resurfacing and an absence of corneal scarring, epithelial adhesion remains impaired, so that the cornea remains vulnerable to further epithelial detachments at the site of injury. Typically, a patient experiences an episode of severe pain on opening the eyes after a night's sleep, as the opening upper lid pulls on the poorly adherent epithelium and triggers an attack. The history alone should suggest the likely diagnosis. Between attacks, the cornea may look normal on biomicroscopy but a few, tiny epithelial microcysts, which take up fluorescein in a brilliant and distinctive manner, often mark the affected zone and can direct the clinician's attention to the region requiring treatment.

Answer 231

A common cause of recurrent erosion is glancing trauma with a flexible object such as a baby's fingernail, twig or a plastic implement. This scuffs off the corneal epithelium at the site of contact, probably taking with it a layer of the underlying epithelial basement membrane critical for epithelial reattachment once epithelial resurfacing has taken place. ## Footnote Occasionally, recurrent erosion may occur as a complication of bilateral epithelial basement membrane, or map-dot-fingerprint disorder. Here, there is an intrinsic, sometimes inherited, defect in epithelial adhesion which gives rise recurrent erosion attacks after minimal trauma or arising spontaneously; the risk of attacks is bilateral and the disorder is characterized by clusters of epithelial dots or of subepithelial map or fingerprint-like patterns detected by retro-illumination at the slit lamp.

Answer 232

In the first instance, attacks are treated with a simple lubricating ointment at night to reduce friction between the upper lid and the globe. Nightly use of hypertonic agents to draw water from the cornea, such as 5% sodium chloride drops or corn syrup, is also advised. Other conservative measures include the use therapeutic hydrogel contact lenses or gas-permeable scleral lenses. Doxycycline prescribed with steroid eye drops may also be effective. ## Footnote Where such measures fail, a surgical approach using corneal micropuncture or phototherapeutic (laser) keratoplasty (PTK), to create a subepithelial scar at the site of the original injury, may give long-lasting relief or a permanent cure.

Answer 233

This responds quickly to topical steroids. Dilation of the pupil with cyclopentolate 1% to overcome the associated spasm of the ciliary muscle and application of a lubricant gel is the standard treatment. Although often given, there is no evidence for the application of topical antibiotics.

Answer 234

with a needle under topical anaesthesia ## Footnote Where the foreign body contains iron, a rust ring may remain which can be removed with a small, rotating burr. Subtarsal objects can often be swept away with a cotton wool bud from the everted lid. The patient is then treated as for an abrasion. If there is any suggestion that a foreign body may have penetrated the globe, the eye must be carefully examined with dilation of the pupil to allow a good view of the lens and retina. A radiograph of the orbits, with the eyes looking up and then down, or a CT scan, may also be indicated if an intraocular foreign body is suspected. Microsurgical techniques can be used to remove foreign bodies from the eye under direct view.

Answer 235

Once identified, no further examination of the globe should be performed but a shield should be gently placed over the eye and the patient referred for urgent ophthalmic assessment and treatment. It should be assumed that the patient will need surgery under general anaesthesia and the patient prepared appropriately and kept nil by mouth. These serious injuries, often with grave implications for sight, require careful microsurgical suturing to restore the integrity of the globe.

Answer 236

This responds to treatment with steroids and dilating drops. It may be accompanied by elevated intraocular pressure requiring additional medical treatment.

Answer 237

This usually settles with rest, but a re‐bleed may occur in the first 5–6 days after injury. Children may sometimes require admission to hospital for a few days, while adults can be treated at home, provided they can rest and no complications develop. Steroid eye drops are given for a short time, together with dilation of the pupil. Steroids may reduce the risk of re‐bleeds.

Answer 238

The commonest complication is a raised ocular pressure, particularly if there is a secondary bleed, which tends to be more severe than the first. It is for this reason that rest is important, although the patient can be ambulant. Raised pressure is due to the accumulation of empty, red cell 'ghosts' in the trabecular meshwork or damage to the drainage angle itself (e.g. angle recession). It usually responds to medical treatment, but occasionally surgical intervention is required. When the hyphaema has settled, it is important that the eye is carefully checked for other complications of blunt trauma. A hyphaema clears more slowly after trauma in patients with sickle cell disease because the hypoxic and acidic environment within the anterior chamber precipitates sickling, and the rigid sickle cells are more difficult to remove via the trabecular meshwork.

Answer 239

In commotio retinae, the affected zone of retina opacifies and obscures the underlying choroidal detail. It usually resolves, but requires careful observation, since retinal holes may develop in affected areas and may lead to subsequent retinal detachment.

Answer 240

Retinal dialysis, a separation of the retina from the ora serrata, requires surgical intervention to repair any detached retina.

Answer 241

A vitreous haemorrhage although it may absorb over several weeks may require earlier removal by vitrectomy. An ultrasound scan is useful in detecting associated retinal detachments when the retina cannot be viewed directly.

Answer 242

Extensive damage to the limbus may prevent resurfacing of the cornea with epithelium. A prolonged epithelial defect may lead to a corneal 'melt' (keratolysis). Stem cell deficiency is treated later, by limbal stem cell transplantation, for instance from the normal, fellow eye or from a donor source. Alternatively or additionally, an overlay of amniotic membrane can be applied to the damaged surface, which protects and maintains the underlying tissue and promotes epithelial resurfacing. It is also possible to resurface the cornea by transplanting expanded sheets of corneal limbal or even oral mucosal cells, grown in culture.

Answer 243

Place an **eyeshield** over an eye suspected of having a penetrating injury.

Answer 244

2.2 billion ## Footnote Defined as: distance acuity worse than 6/12 or N6 for near)

Answer 245

43 million people are blind ## Footnote Visual acuity less than 3/60. 90% of the blind live in the poorest parts of the developing world.

Answer 246

The prevalence of blindness is greater in women in all regions. Nearly, two-thirds of the world's blind are women. In the developed world, this is partly because women live longer than men, but in the developing world, cultural factors can mean that women are less informed about opportunities for treatment and have fewer resources to pay for and access care. In sub-Saharan Africa and south Asia, the proportion of eligible women who receive cataract surgery may be half that for men.

Answer 247

Of the surgical methods available for treatment, **extracapsular cataract extraction** has been the method of choice in the developing world, since it is cheaper than phacoemulsification and not dependent on expensive, high‐tech equipment and support costs. However, increasingly, **small incision cataract surgery (SICS)** is being adopted, which is a low‐cost and faster procedure permitting the use of intraocular lens implants. Since sutures are not used, rehabilitation is faster.

Answer 248

In India, where cataract blindness remains a significant problem, the Aravind Eye Care system has created a highly efficient, high-volume, low-cost, self-financing system for performing cataract surgery. The system uses income from patients who can afford to pay for private surgery, to pay for the poor, who receive free surgery. Patients are screened in eye camps and those in need of surgery or other treatment are referred to hospital.

Answer 249

Trachoma is endemic in 48 countries, in Latin America, Africa, the Middle East, Asia and Australasia. Some 157.7 million people living in endemic areas require prophylactic treatment. In 2019, there were 2.5 million people with trachomatous trichiasis, falling from 7.6 million in 2002. Ten percent of the world population are potentially at risk, mostly in dry, hot parts of the developing world.

Answer 250

Transmission is by the transfer of the elementary bodies of the bacteria from one person to another, usually from the nasal and ocular secretions of an infected child. This may involve eye-to-eye transmission with the fingers, the sharing of towels, handkerchiefs and bedclothes, coughing and sneezing. In addition, eyeseeking flies (e.g. Musca sorbens) act as important vectors, carrying the infective particles from eye or nose, to other individuals.

Answer 251

Initially, follicles (collections of lymphocytes) appear in the superior tarsal conjunctiva, followed by papillae. Then, the limbal cornea is invaded by superficial vessels (pannus), with the development of peripheral scarring. The first infection with C. trachomatis does not cause serious disease. Repeated episodes lead to extensive upper tarsal conjunctival scarring in children and young adults, and lid deformity and trichiasis, usually in middle-aged adults, which together exacerbate the corneal changes. Continued re-infection leads to chronic corneal scarring and blindness.

Answer 252

SAFE strategy = Surgery, Antibiotics, Face washing, Environmental change

Answer 253

A single dose of oral **azithromycin** (20 mg/kg up to 1 g) is effective in treating infected individuals, but the disease must be eradicated from all individuals in a community to prevent re-infection, and treatment must be repeated yearly. This is expensive, and the disease will recur unless changes are made to the environment in which the organism prospers. This is much harder to achieve.

Answer 254

The filarial nematode, *onchocerca volvulus*

Answer 255

In 2017, 220 million people required preventative anti-helminthic and it was estimated that 1.15 million people had sight loss due to onchocerciasis.

Answer 256

Microfilariae in the skin of an affected patient are ingested when the female blackfly (e.g. Simulium damnosum) bites a human for a blood meal. The microfilariae develop into infective larvae in the fly, pass to its mouth and are then transmitted to a human with the next bite. Following moulting, the larvae develop into adult worms in the body. They are found in subcutaneous skin nodules (onchocercomata). A female worm may produce 1600 microfilariae a day and generate a body load of 150 million. These migrate in the dermis and its lymphatics and die after a couple of years if they are not taken up into a blackfly.

Answer 257

The adult female worm is 30-80 cm long and the male 3-5 cm long. In the human body they have a lifespan of 9-14 years. ## Footnote A female worm may produce 1600 microfilariae a day and generate a body load of 150 million. These migrate in the dermis and its lymphatics and die after a couple of years if they are not taken up into a blackfly.

Answer 258

Fluffy, punctate stromal keratitis. Each opacity representing an inflammatory reaction around a dead microfilarium.

Answer 259

Water courses provide the breeding grounds for the blackfly, which is why those whose work or daily life takes them to the banks of rivers are most at risk of infection - hence the name river blindness. Control programmes are aimed at the blackfly vector, by spraying its habitat with larvicides, trapping methods and the removal of vegetation from breeding sites. The onchocerciasis control programme has been successful in the endemic West African region and South America. A low population density in affected areas (principally farming and fishing communities) increases the likelihood of multiple blackfly bites. Protective clothing reduces the possibility of bites but may not always be practical. Vector control programmes are a long-term proposition because the female worm lives for 9-14 years, which perpetuates microfilarial infiltration of the skin.

Answer 260

Ivermectin (given once a year)

Answer 261

The African programme for onchocerciasis control (APOC) had developed a system whereby the local community is responsible for the delivery of ivermectin treatment. This has now closed but the work continues with the Expanded Special Project for the Elimination of Neglected Tropical Diseases in Africa (ESPEN).

Answer 262

Dietary carotenoids from dark, leafy green vegetables, carrots, red palm oil, mangoes and papayas, and so on are absorbed and broken down to release vitamin A (roughly 12 molecules of carotene for every molecule of vitamin A). Preformed vitamin A is available in breast milk, liver, fish oils, eggs and dairy products.

Answer 263

Xerophthalmia

Answer 264

In countries where vitamin A deficiency is prevalent, 50% of those affected die within 2 years of becoming blind.

Answer 265

About 190 million children under 5 years of age suffer from vitamin A deficiency and some 5-10 million develop xerophthalmia each year, with loss of sight in half a million. The peak incidence occurs between 3 and 5 years of age.

Answer 266

1. Night blindness 2. Ocular surface xerosis (conjunctival or corneal) 3. Corneal ulceration or focal melting (keratomalacia)

Answer 267

Due to lack of the visual pigment rhodopsin

Answer 268

Vitamin A deficiency causes a loss of ocular surface wettability due to a reduced expression of epithelial glycocalyx mucins and a loss of goblet cells and their secreted gel mucin. Tear production may also be reduced. This results in: * Conjunctival xerosis: involving keratinization, thickening and non-wetting of the conjunctiva, frequently with Bitot spots near each limbus (foamy triangular surface plaques containing keratinized cells and saprophytic bacteria) * Corneal xerosis: involving punctate keratiopathy or diffuse drying of the cornea, usually with stromal oedema. it imarsnusmunan ine

Answer 269

Phthisis bulbi is an clinical condition representing an end-stage ocular response to severe eye injury or disease damage.

Answer 270

Treatment with vitamin A supplementation, fortification of food or increasing the natural dietary intake is highly cost-effective (the WHO recommends the provision of two doses of vitamin A annually to children between the ages of 6 and 59 months). A protein-rich diet is also advised. Delivery of supplements is often combined with immunization programmes. Education about breastfeeding, diet and food availability and preparation is also important. Care should be taken in women of childbearing age, as vitamin A in large doses may have teratogenic effects; lower doses are therefore recommended.

Answer 271

Measles is an important cause of corneal scarring and childhood blindness and its severity is exacerbated by vitamin A deficiency. During infection with measles, vitamin A stores are significantly depleted, which can result in severe corneal disease. Vitamin A deficiency also increases mortality from this disease. Associated exposure keratopathy, herpes simplex keratitis and other secondary infections may also cause corneal opacification. This may be compounded by treatment with local remedies that traumatize the eye, or cause infection or chemical burns.

Answer 272

Southeast Asia

Answer 273

Gonorrhoeal keratitis may progress rapidly to corneal perforation and endophthalmitis. Chlamydial infection is the commonest cause and the associated keratitis, if untreated, may progress to corneal scarring. It can also be associated with a pneumonitis. Because of the systemic implications of these eye infections, both are treated with systemic and topical antibiotics. Topical instillation of povidone-iodine eye drops into the eyes of neonates, at the time of delivery, is a simple and cost-effective means to prevent either disease.

Answer 274

Development of the eye begins early in utero, with the optic grooves appearing at 3 weeks, and is largely completed at 7 months of gestation. The visual pathways continue to mature over the next few months in and ex utero. The globe continues to grow post-natally.

Answer 275

Teratogenic events in the first 3-8 weeks can result in severe eye abnormalities. The choroidal fissure closes at 7 weeks, and incomplete closure can result in chorio-retinal and/or optic nerve colobomas.

Answer 276

Adequate stimulation of both retinas in the first 6-8 years of life is essential to achieve normal visual acuity in adult life. Visual deprivation of one or both eyes from any cause can result in amblyopia (a 'lazy eye').

Answer 277

1. Eyes are structurally normal 2. No abnormal eye movements 3. No other developmental concerns ## Footnote Such babies can be observed until & months age, by which time most cases improve spontaneously. If there is no improvement after this time, a brain scan and electro-diagnostic testing (ERG and VEP) are indicated.

Answer 278

Briefly holds gaze on an object Takes interest in (stares at) surroundings, blinks at bright lights Tracks vertically and horizontally Makes eye contact at 6-8 weeks; fixes on mother's face

Answer 279

Follows adults or moving objects with eyes across midline Displays interest in human faces Observes own hands Briefly fixes on and reaches for small objects

Answer 280

Recognizes objects at home, tracks across the room Interested in pictures, inspects toys, enjoys hide-andseek Responds to smiles and voices, develops stranger anxiety

Answer 281

Enjoys picture books and points to pictures Holds objects close to eyes to inspect

Answer 282

Recognizes faces in photographs Begins to inspect objects without touching them Likes to watch moving objects, such as wheels on a toy vehicle Watches and imitates other children 'Reads' pictures in books

Answer 283

* Copies patterns * Recognizes colours * Can close eyes on request and may be able to wink

Answer 284

* Draws a recognizable person and house and names pictures * Uses eyes and hands together with increasing skill * Moves and rolls eyes expressively * Can place small objects into small openings * Demonstrates visual interest in new objects

Answer 285

Wide set eyes

Answer 286

Humphrey instrument or manual perimetry with the Goldmann instrument. ## Footnote For the younger child, tests are more observational, where the clinician places objects (typically bright toys) randomly in various positions in the visual field, and observes the child's response - normally a rapid head and eye movement in the direction of the toy.

Answer 287

Binocular vision is the ability of the higher visual centres of the brain to process the visual signals from both eyes simultaneously, to produce a single, three-dimensional visual percept. ## Footnote It is a function in higher evolved species where the location of the eyes in the head permits an overlap of the visual fields when the eyes are directed at an object of regard. This condition is maximized in humans and in sub-human primates where the eyes are frontally disposed, thus achieving a large binocular visual field. Since each eye views the visual scene from a slightly different angle, the images on each retina have slight horizontal disparity and it is this which creates the three-dimensional percept, carrying depth and distance information, which is the basis of stereopsis.

Answer 288

Lang, TNO and Titmus tests, the Wirt Fly test and the synoptophore - often referred to by children as 'putting the lion in the cage test'.

Answer 289

It is important to remember that it may be more difficult to see a bright red reflex in heavily pigmented fundi (e.g. Asian or Afro-Caribbean eyes) as more light is absorbed and less reflected back. This apparent absence of a red reflex is a common cause of referral to the ophthalmologist. Examining the fundus in a child takes considerable patience and skill. It is easier after pupillary dilatation with eye drops, usually cyclopentolate.

Answer 290

Those born prematurely, or showing developmental delay, including that resulting from birth hypoxia. Those with multisystem disorders or genetic syndromes such as Trisomy 21.

Answer 291

**5%** (the Baltimore Pediatric Eye Disease Study).

Answer 292

1. Rhabdomyosarcoma 2. Bleeding into vascular malformation 3. Infection e.g. orbital cellulitis

Answer 293

These lesions, extending into the lids, typically present within a few weeks of birth. They can grow rapidly and induce astigmatism or ptosis, with resultant amblyopia. Timely treatment with topical (Timolol) or systemic beta-blockers (Propranolol) is essential.

Answer 294

These present in infancy and early childhood as well-defined lesions along the supero-temporal, or less commonly, supero-nasal orbital rim. Treatment is with surgical excision.

Answer 295

The treatment is surgical and involves shortening of the levator muscle (resection) or suspending the eyelid from the brow (brow suspension) using material such as silicone or fascia lata harvested from the leg.

Answer 296

Congenital epiphora - specifically refers to watery eyes resulting from congenital obstruction of the nasolacrimal duct. Spontaneous resolution is seen in many cases within the first year of life. Persistent cases can be treated with syringing and probing, with a high success rate.

Answer 297

Juvenile idiopathic Arthritis (JIA)-related uveitis ## Footnote The presentation of uveitis in children differs from that in adults as it does not cause redness or pain. Consequently, it may be overlooked and children with uveitis or diseases that may cause uveitis need regular screening.

Answer 298

an enlarged eye (bupthalmos); photophobia epiphora (beware of diagnosing an obstructed nasolacrimal duct in these children).

Answer 299

Coats disease and retinoblastoma

Answer 300

This is a form of exudative vascular retinopathy, characterized by abnormally dilated vessels in the peripheral retina that leak blood and blood products. Yellow, cholesterol-rich fluid forms under the retina, resulting in an exudative detachment. It can be difficult to distinguish from retinoblastoma, but an ultrasound B-scan can be used to exclude a mass lesion.

Answer 301

1. Retinal dystrophies (retinoschisis and rod cone dystrophies). 2. Albanism 3. Coats disease 4. Astrocytomas are hamartomatous lesions of the retina. 5. Retinoblastoma

Answer 302

Retinal development continues through gestation, and vascularization is completed near term. Premature birth interferes with normal retinal vascularization, with a risk of abnormal retinal vascular proliferation that can cause retinal scarring and/or detachment (ROP). Babies born before 32 weeks gestation or of birthweight ≤1500 g are at risk of ROP and undergo regular screening eye examinations in the first few weeks of life. Most cases do not require treatment, but ROP beyond a certain threshold will require prompt laser treatment of the avascular retina to reduce risk of visual loss.

Answer 303

1. Retinopathy of prematurity (ROP) 2. Strabismus 3. Refractive error 4. Cortical visual impairment and developmental delay

Answer 304

* Optic pathway gliomas, some of which are related to neurofibromatosis (type 1). * Extrinsic compression of the optic pathway from supra-sellar tumours (craniopharyngiomas). | These children often present with visual loss or nystagmus.

Answer 305

It is not uncommon for the eyes to converge or diverge randomly during the first 2-3 months while the fixation system is still developing. This is referred to as neonatal ocular misalignment, and can be kept under observation unless there are concerns about the child's vision. Persistence of ocular misalignment beyond 3 months warrants referral to an ophthalmologist.

Answer 306

1. Refractive 2. Non-refractive 3. Mixed 4. Neurogenic 5. Myogenic 6. Obstruction of the optical media (e.g. cataract)

Answer 307

Dilated fundoscopy (for external evidence of trauma + retinal haemorrhage)

Answer 308

**Mild**: visual acuity worse than 6/12 to 6/18. **Moderate**: visual acuity worse than 6/18 to 6/60. **Severe**: visual acuity worse than 6/60 to 3/60. **Blindness**: visual acuity worse than 3/60. ## Footnote The definition of blindness, a visual acuity of < 3/60 with the best possible refractive correction, can also be met if there is a visual field loss to less than 10°, in the better eye.

Answer 309

Near vision impairment is defined as an acuity worse than N6 at 40 cm.

Answer 310

An estimate in 2010, of the age-standardized prevalence of blindness in adults ≥50 years, was **≤0.4%** in high-income regions compared to levels of up to **6%**, in western sub-Saharan Africa.

Answer 311

Globally, uncorrected refractive errors are the main cause of moderate and severe distance visual impairment that can be corrected and near visual impairment; cataracts remain the leading cause of blindness in middle- and low-income countries.

Answer 312

Protanomaly makes certain shades of red look more green and less bright.

Answer 313

Deuteranomaly is the most common type of red-green color vision deficiency

Answer 314

Tritanomaly makes it hard to tell the difference between blue and green and between yellow and red ## Footnote Tritanopia (absence of function) makes someone unable to tell the difference between blue and green, purple and red, and yellow and pink. It also makes colors look less bright.

Answer 315

X-linked recessive ## Footnote Deuteranopia or more commonly deuteranomaly is the usual cause of red-green colour blindness. Protanopia or protonomaly is more unusual. Both are inherited in an X-linked recssive manner. Thus, males (1 in 12) are more commonly affected than females (1 : 200). It affects the ability to detect long and middle wavelengths of the optical spectrum and hence to sense the colours green or red and to discriminate their admixtures. Red and green are colours used in traffic lights and signalling systems.

Answer 316

In the United Kingdom, a Certificate of Visual Impairment is completed for a child. This is also useful nationally in planning visual services for children. It is important to provide resources for the whole family of a child with visual impairment. Financial assistance may also be available for those with severe visual impairment. Every local authority in the United Kingdom will have a qualified teacher of the visually impaired (QTVI) and other educational and social care staff trained to provide for the special educational needs of children with visual impairment. The local authority will also provide an education health and care (EHC) plan for young people up to 25 years of age.

Answer 317

In the United Kingdom, people with visual impairment are eligible to be registered as sightimpaired (partially sighted) or severely sight-impaired (blind) (Table 20.1). This is a process initiated by the consultant ophthalmologist, by completing a Certificate of Visual Impairment (CVI). The process of registration enables the affected individual to access support from social services and entitles them to certain concessions. People who are registered as severely sight-impaired/blind or sight-impaired/partially sighted are not automatically entitled to any welfare benefits; this is subject to age and other circumstances.

Answer 318

* RNIB (Royal National Institute of Blind People www.rnib.org.uk * The Royal College of Ophthalmologists www.rcophth.ac.uk * VIScotland www.ssc.education.ed.ac.uk * CAF - Contact a Family - for families with disabled children www.cafamily.org.uk

Answer 319

Gentamicin (broad spectrum including pseudomonas). Neomycin (in combination with steroid drops). Tobramycin.

Answer 320

Azithromycin (trachoma).

Answer 321

Propamidine isethionate. Chlorhexidine (specialist formulation). Polyhexamethylene biguanide (PHMB) (specialist formulation).

Answer 322

Aciclovir. Ganciclovir (topical and slow release implants available to treat CMV retinitis). Trifluorothymidine (specialist formulation).

Answer 323

(Specialist formulation of drops is required.) Pimaricin (natamycin) 5%.

Answer 324

Bromfenac. Diclofenac. Flurbiprofen sodium. Ketorolac trometamol.

Answer 325

Betamethasone (also available combined with an antibiotic). Dexamethasone (also available combined with an antibiotic). Fluorometholone. Loteprednol etabonate. Prednisolone. Rimexolone. ## Footnote Intravitreal preparations (dexamethasone, fluocinolone acetonide) are available to treat macular oedema associated with diabetes and retinal vein occlusion.

Answer 326

Lodoxamide. Nedocromil. Olopatadine (also antihistamine). Sodium cromoglycate.

Answer 327

Antazoline. Azelastine. Epinastine. Ketotifen. Levocabastine. Olopatadine (also mast cell stabilizer).

Answer 328

Acetlycysteine.

Answer 329

Atropine. Cyclopentolate hydrochloride (routinely used for therapeutic pupillary dilation). Homatropine hydrobromide. Tropicamide (routinely used for diagnostic pupillary dilation).

Answer 330

Phenylephrine hydrochloride.

Answer 331

Betaxolol. Carteolol. Levobunolol. Timolol.

Answer 332

Bimatoprost (synthetic prostamide). Latanoprost. Tafluprost. Travoprost.

Answer 333

Brimonidine tartrate. Apraclonidine.

Answer 334

Brinzolamide. Dorzolamide. (Systemically, acetazolamide is used to treat acute elevation of intraocular pressure.)

Answer 335

Pilocarpine.

Answer 336

Lidocaine hydrochloride. Oxybuprocaine hydrochloride. Proxymetacaine hydrochloride (causes less stinging on initial application). Tetracaine hydrochloride.

Answer 337

Carbomers (polyacrylic acid). Carmellose sodium. Hypromellose. Macrogols (polyethylene glycols). Polyvinyl alcohol. Sodium chloride 0.9%. Sodium hyaluronate. Eye ointments containing paraffin.

Answer 338

For the treatment of wet age-related macular degeneration, retinal vein occlusion and diabetic macular oedema. Aflibercept. Pegaptanib. Ranibizumab.