elder Flashcards
Xerophthalmia
A major cause of childhood blindness in Africa
Due to Severe Vitamin A deficiency → lack of tear production → dry eyes
Presentation
Characteristic Bitot’s spots - triangular conjunctival keratin buildups
Investigations Standard findings in dry eye: Tear film break up time time is reduced (<5) Schirmer's test is positive >10mm Ocular surface staining
What vitamin deficiency is most likely to cause with xerophthalmia?
A
Blepharitis associated with which bacteria?
chronic inflammation of the eyelid of any cause. It is typically associated with Staphylococcus aureus infection.
Anterior - lashes and eyelid crusts, staphylococcus,
Posterior - eyelids normal, foamy tear film - worser tx response
what is the presentation of blepharitis?
crusts at eyelid margin and lashes
foamy tear film
meibomian cysts with posterior blepharitis
what risk is associated with recurrent unilateral blepharitis?
sebaceous cell carcinoma
what is the glaucoma triad?
raised IOP, abnormal disc, visual field defects?
IOP can be normal in glaucoma.
Gold standard for IOP - Goldmann tonometry 11-21mhg
what does the neuroretinal rim and optic cup contain?
neuroretinal rim - retinal neuronal cells
optic cup - central retinal vessels.
normal optic cup-to-disc ratio?
0.3
retinal detachment signs?
curtain fall over vision, floaters (PVD), shaffer sign (pigment cells in vitreous) Weiss ring (PVD)
what method attached neurosensory retain to retinal pigment epithelium?
hydrostatic forces
Difference between rhegmatogenous, tractional and exudative RD
rhegmatogenous - break/tear in neurosensory retina, fluid accumulate between NSR and RPE , PVD associated
tractional - scar tissue - adhesional vitreous traction on retina DR and ROP associated
exudative - sub-retinal fluid accumulation due to failure of blood-retinal barrier –> uveitis, choroidal tumour/neovascularization, uveal effusion syndrome.
refractive power =
1/focal length of lens (m)
total RP - 60Dioptres
cornea 2/3
lens 1/3
axial length normal range
22-24mm
Myopia - long eye , focal point in front of retina, short-sighted
hyperopia - short eye, focal point behind retina, long-sighted (further away object allows focal point move forwards)
astigmatism
refractive power of corneal not uniform due to shape of it. blurry vision, two inaccurate focal points.
What is the wavelength of the ND:YAG laser used in peripheral iridotomy?
1064
horners syndrome
orders?
What is used to diagnose horners
First order : lesions of brain and spinal cord
Second order : Pancoast tumour and neck trauma
Third order: no anhidrosis. Caused by cavernous sinus lesions and internal carotid dissection.
cocaine and apraclonidine (alpha agonist - mydriasis) – more dilation
hydroxyamphetamine and dilute adrenaline - localise 3rd order disease
Painful Horners
carotid dissection until proven otherwise.
CN4 palsy test??
Park Bielschowsky
1- find hypertrophic eye in primary position
2. assess change in diplopia with horizontal gaze - diplopia worse with contralateral gaze direction
left affected - right movement worse
3. head tilt - diplopia worse on ipsilateral head tilt
pseudoxanthoma elasticum
- angioid streaks
- radiating sections of Bruch membrane of chorioid that are calcified and broken
- from optic disc out retina
- can cause choroidal neovascularisartion and visual loss
Angioid streaks
PEPSI pseudoxanthoma elasticum pagests Sickel cell idiopathic
which glands involved in sebaceous gland carcinoma
meibomian and zeis
misdiagnosed as unilateral blepharitis
associated with Muir Torre syndrome –>
Muir-Torre syndrome (MTS) rare inherited disorder that involves at least one sebaceous tumor and/or keratoacanthoma in addition to one visceral malignancy eg colorectal cancer. Sebaceous adenomas are the most common cutaneous tumors in MTS - multiple yellow papules or bumps on areas such as the trunk, face, and scalp.
The cyst in degenerative retinoschisis typically forms between which layers of neurosensory retina?
the outer plexiform and inner nuclear layers of the retina
common cause of infant epiphora and cause?
congenital nasolacrimal duct obstruction
imperforate membrane over valve of hasher.
<12 months of age Massage + topical antibiotics + observation >12 months of age Syringing and probing Silicone stent intubation Dacryocystorhinostomy (DCR)
ametropia
refractive error present
myopia or hyperopia
spherical lenses
Used to correct ametropia and presbyopia
-ve D lenses are concave and diverge light → correct myopia
A myopic patient
+ve D lenses are convex and converge light → correct hyperopia and presbyopia
E.g : A hyperopic patient would like spectacles to allow reading at 20cm. What power should the lenses be?
The lens has to have a focal point which matches the far point
The far point in this case is 20cm, so a lens with a focal length of 20cm is needed
Power=1/focal length(m)
P=1/0.2 = 5
Answer = +5D
topic lenses
Used to correct astigmatism
Is composed of a sphere and cylinder
The sphere acts in all meridians
The cylinder only acts in a specific meridian, this allows it to treat astigmatism.
Inclusion Body Chlamydial Conjunctivitis
Chlamydia trachomatis, a gram negative intracellular obligate organism
Associated with serotypes D-K
Subacute (2-3wks) unilateral conjunctivitis in young people
Associated with STI symptoms such as urethritis
Inferior follicular conjunctivitis with persisting mucopurulent discharge and lymphadenopathy
Immunotypes L1, L2, L3 cause Lymphogranuloma Venereum
Inclusion Body Chlamydial Conjunctivitis Tx
1g oral azithromycin STAT or 100mg doxycycline BD for 14 days
POAG
Chronic glaucomatous change due to optic nerve damage with an open anterior chamber angle.
Normal IOP, visual field defects
Black people - myopia -> POAG
Asians - hyperopia Angle closure
side effects of Latanoprost in Glaucoma
increase uveoscleral outflow
Iris pigmentation Lash lengthening Hyperaemia Uveitis Macular oedema
Avoid in uveitis as it worsens inflammation
Beta blockers side effects
reduces aqueous production
Bradycardia
worsen asthma
avoid in lung path and breast-feeding
Alpha agonist SE
Decrease aqueous production and increase uveoscleral outflow
Dry mouth
Dry eyes
A2 selective blockers are lipophilic, and can cross the blood brain barrier, resulting in respiratory depression in the young
Cholinergic agonists (e.g Pilocarpine) SE
ciliary contraction, opening the trabecular meshwork → Increases trabecular outflow
causes miosis which relieves pupil block, where the the pupil has fallen down and is obstructing the flow of aqueous
Polyuria Diarrhea Lacrimation Sweating salivation
Carbonic anhydrase inhibitors (e.g Brinzolamide)
SE
Inhibit anhydrase isoenzyme II → reduce aqueous production
Hypokalemia
Metabolic acidosis
contras
Sulfonamide sensitivity
Renal/liver failure
what is metamorphopsia
distortion of visual objects
seen in macular disease eg macular hole, macular degeneration
normal IOP in infants
10-12mmhg
primary congenital glaucoma
glaucoma in the first year of life due to malformed anterior chamber angles
Mostly sporadic but can be AR
CYP1B1 gene mutation association
Presentation
Hx: infant boy + haab striae + buphthalmos + large corneal diameter + epiphora
Investigation
Elevated IOP (normal in infants is 10–12 mmHg)
Widened corneal diameter
Management
Angle surgery: Goniotomy if the cornea is clear. If the cornea is cloudy, then trabeculotomy can be attempted.
how many layers of tear film
3 Lipid layer The thinnest and most superficial layer Produced by the meibomian gland (Sebaceous). Prevents evaporation of the tear film.
Aqueous layer
Produced by the lacrimal gland.
Thickest layer
Has an immune function
Mucin layer
Deepest layer
Produced by conjunctival goblet cells.
Spreads the film evenly and keeps it stable on the ocular surface.
glands of lacrimation
Lacrimal Gland (main)
Sensory innervation → lacrimal nerve (branch of CNV1)
Lacrimation (secretomotor) → Parasympathetic (CN7)
Accesory Lacrimal Glands
Krause and Wolfring glands are accessory lacrimal glands which maintain a basal aqueous layer
Krause glands are found at the conjunctival fornices and are more abundant in the upper fornix
Wolfring glands a less numerous but bigger. They are found at the tarsal plate.
Eyelash Associated Glands
The glands of Moll and Zeis both service eyelash follicles
Moll glands are apocrine (modified sweat glands)
Zeis (and Meibomian glands) are holocrine (sebaceous)
What muscle is involved in the lacrimal pump mechanism?
Orbicularis
what is the Lamella
The eyelid is anatomically divided into 2 lamella (sections) by the Gray line, the outermost margin of the orbicularis muscle.
Anterior lamella contains: skin and orbicularis
Posterior lamella contains: tarsal plate and conjunctiva
muscles for eyelid retraction
levator palpebrae superioris, mullers and frontalis
levator - cn3
frontalis - CN7
muller - SNS
muscles for eyelid
obicularis - CN7
most common primary intraocular malignancy in children?
Retinoblastoma
Arises from Photoreceptor cells
Associated with RB1 mutation on Ch13.
Most commonly sporadic but can be AD
Histopathology classically shows Flexner rosettes
Presentation : 3 year old + leukocoria (often unilateral) + strabismus + decreased visual acuity + white round mass in fundus + ultrasound shows calcification
Mx of retinoblastoma
enucleation
strabismus ? eye direction disorder
esotropia - in
exotropia - out
hypotonia - down
hypertropia - up
vergence ?
Biconcave lens vergence
Biconvex lens vergence
vergence
Vergence is the amount of spreading (divergence) or coming(convergence) together of light. It is measured in diopters (D), where D is the reciprocal of the distance to the point where light rays would intersect if extended in either direction (focal length). D=1/f(m).
images form at the light intersection
A plus lens converges light / biconvex ()
A minus lens diverges light / biconcave )(
lens formula
U+D=V
U → vergence of light entering lens (object rays)
D → vergence added to light by lens (lens power)
V → vergence of light leaving the lens (image rays)
Light from an object 2m away is travelling to a +2D lens. At what distance is the image going to be formed?
- U= 1/2 = -0.5D
- Light coming from a natural object is divergent (minus)
- D = +2D
- V = -0.5+2 = +1.5D
- Recall that D=1/f(m), therefore, 1/1.5 = 0.67m
- The image will form 0.67m on the other side of the lens
D = reciprocal of distance
Which medication is most likely to cause bilateral primary angle closure?
topiramate
POAG
PACG can manifest in several different:
- Anatomically narrow drainage angle (ANDA): On gonioscopy the AC angle is narrow and the person is likely to be at higher risk of angle closure
- Iridotrabecular contact (ITC): on gonioscopy the AC angle is closed
- Acute primary angle closure (APAC): ITC + acute symptomatic elevated IOP
- Primary angle closure glaucoma: ITC + Glaucomatous damage + elevated IOP or PAS or APAC episodes
pathology of POAG
Pathology
Pupil block mechanism (Majority):
Apposition of iris to lens → abnormal aqueous flow through the pupil → increase in pressure difference between the posterior and anterior chambers → anterior bowing of the peripheral iris leading → peripheral anterior synechiae (PAS) → angle closure → obstructed aqueous outflow → elevated IOP → glaucomatous optic nerve damage
Plateau iris configuration (East asian):
Flat iris + anteriorly positioned ciliary processes → iris is pushed forward → angle closure.
signs of Resolved/Past APAC attacks?
Descemet’s membrane folds
Glaukomflecken
Mx of POAG?
APAC
First line: urgent admission + IV acetazolamide
Adjuncts: timolol + apraclonidine + steroids + pilocarpine + lie the patient supine
Monitor and consider systemic hyperosmotics (IV mannitol)
Definitive treatment is bilateral peripheral iridotomy.
PACG
Aim is to control IOP over time
Bilateral peripheral iridotomy
Cataract extraction is effective in acute and chronic stages
POAG
Asymptomatic at first but will develop visual field defec
Topical IOP lowering medications (1st line)
- Topical prostaglandin or beta-blocker (others options are alpha-2 agonists, carbonic anhydrase inhibitors)
- No IOP reduction → try alternative first line
- Insufficient IOP reduction → combine topical medications
Surgical IOP lowering procedures (2nd line)
Issue with medical adherence but IOP is controllable → Selective laser trabeculoplasty (SLT)
Uncontrolled IOP despite maximum meds→ Trabeculectomy with anti-scarring mitomycin C (MMC) or 5-FU
blood supply of CN2
Intraocular → short posterior ciliary artery
Rest → ophthalmic artery (Pial vessels)
presbyopia?
With age, the lens hardens and the anterior capsule thickens
Lens power decreases because it loses the ability to change shape with accommodation
The decline of accommodative power with age:
At birth → 16D
25 years → 8D
50 years → 2D
60 years → <1D
People around the age of 50 invariably require reading glasses
Presbyopia is delayed in myopes (short-sighted people)
hyphema ?
blood in the anterior chamber
ocular trauma
microhyphema - RBC visible only on slit lamp
Treatment Admit for steroids and bedrest Monitor IOP for red cell glaucoma No improvement → AC paracentesis No - trabeculectomy
what are the three types of ametropia
ametropia results if power or axial length of eye is outside normal range.
1- myopia = high refractive power, focus in-front retina, short-sighted, -ve lens
2- hyperopia = low refractive power, focus at-back of retina, long-sighted, +ve lens
Bacterial Conjunctivitis MX
red gritty sticky eyes and purulent discharge.
Practice good hand and eye hygiene
Switch to spectacles from contact lenses during the episode
Topical chloramphenicol drops
Systemic antibiotics are reserved for gonococcal conjunctivitis in adults or H.influenzae/Meningococcal conjunctivitis in children
H.influenzae → PO Co-amoxiclav
what causes Bacterial Conjunctivitis in
cool climate
warm climate
children
cool - Strep p , H.I
warm - Haemophilus aegyptius
Children → Haemophilus influenzae
Giant fornix syndrome
Bacterial conjunctivitis where
sequestration of bacteria in the upper fornix of the conjunctiva and is typically seen in the elderly.
order of neuroretinal rim thickness of the optic disc, from thickest to thinnest?
Inferior → Superior → Nasal → Temporal
Parinaud syndrome
supranuclear palsy of upgaze . It is caused by a lesion in the dorsal midbrain
signs of Parinaud syndrome
Signs Bilateral lid retraction - Collier sign Upgaze paresis Convergence retraction nystagmus Large pupil with light-near dissociation (light reflex lost but near accommodation reflex intact)
optic neuritis types
Papillitis: Inflammation of the optic disc. Typically presents in post-viral children with flame hemorrhages and an oedematous optic nerve
Retrobulbar neuritis: disc is spared but the segment behind the eyeball is affected. The disc looks normal in this acute setting. More common in adults
Neuroretinitis: The disc and retina are both involved. Occurs in lyme disease and cat scratch
what causes cat scratch
bartonella henselae and is transmitted by cats.
clinical manifestations of optic nerve disease?
Loss of central vision and eye pain on movement
RAPD
Red green colour loss
clinical manifestations of macular disease?
Distortion of vision (metamorphosia) and loss of central vision
Hyperopic shift (see distance better)
Blue yellow colour loss
what are the two mechanisms of epiphora?
nasolacrimal drainage failure and hyper-secretion.
epiphora causes
Obstruction of the nasolacrimal system Punctal eversion Canalicular fibrosis Lacrimal sac obstruction Nasolacrimal duct obstruction. Orbicularis pump failure Lid laxity CN7 palsy Lateral dermatochalasis Overzealous punctoplasty Hypersecretion Irritation hyper-secretion is typically caused by a foreign body on the ocular surface or lashes rubbing on the ocular surface as in trichiasis and entropion Autonomic abnormalities and pro-secretory drugs like pilocarpine can also cause hypersecretion.
Which condition is most associated with posterior blepharitis
Acne rosacea
retinal hole
A full thickness retinal defect due to atrophy without vitroretinal traction
retinal tears
Retinal tears are full thickness breaks through the retina. Retinopexy is used as treatment in cases which are high risk for progression into retinal detachment (RD). Tears are commoner in myopic eyes, because the surface area of the retina is greater.
types of retinal tears
U-shaped
Typically occurs in the context of PVD
High risk for progression to RD
Symptomatic U-shaped tears are treated with laser retinopexy
Giant Describes are tear which extends greater than a quarter of the retina. Typically occurs in the context of PVD Very high risk for progression to RD Treat with laser retinopexy
Retinal Dialysis
Disinsertion of the retina at the ora serrata (most anterior edge of retina)
Traumatic dialysis is typically located superonasally
Idiopathic dialysis is typically located inferotemporally
High risk for progression to RD
Treat with retinopexy if there is no associated RD
Treat with scleral buckling if there is RD
image quality of biconcave and biconvex lenses
image created by a minus lens (biconcave) is virtual, erect and diminished.
image created by a plus lens (biconvex) can be real or virtual, erect or inverted, and magnified or diminished; all depending on the distance of the object relative to the focal point of the lens.
sympathetic pathway in eye?
1st Hypothalamus → T1 → 2nd Superior cervical ganglion→ 3rd ICA → long ciliary nerve → dilator pupillae.
This sympathetic pathway is compromised in Horner syndrome.
Carotid Cavernous fistula CCF what is it and what are the 2 types?
V malformation between the internal carotid artery and the cavernous sinus
- direct CCF
High flow direct connection between internal carotid artery and cavernous sinus
trauma leading to a fistula
ocular bruit, whooshing sound heard by patient, raised IOP and visual defects
Management is with embolisation - indirect
Low flow connection between the internal carotid artery and cavernous sinus via meningeal branches
Typically occurs spontaneously in elderly hypertensive women
gradual onset irritated eye, increased IOP and corkscrew epibulbar vessels
Most cases self resolve
astigmatism
common and generally treatable imperfection in the curvature of the eye that causes blurred distance and near vision. Astigmatism occurs when either the front surface of the eye (cornea) or the lens inside the eye has mismatched curves.
Astigmatism is when the refractive power is different across the surface of the same medium. E.g the superior cornea might have 49D and and the inferior cornea might have 34D.
What visual field defect is most associated with chronic papilloedema?
Papilloedema is a red flag sign that needs immediate investigation
Acute papilloedema causes an enlarged blind spot
Chronic papilloedema results initially in the loss of the inferior nasal quadrant of vision
causes of epiphora
Obstruction of the nasolacrimal system Punctal eversion Canalicular fibrosis Lacrimal sac obstruction Nasolacrimal duct obstruction.
Orbicularis pump failure Lid laxity CN7 palsy Lateral dermatochalasis Overzealous punctoplasty
Hypersecretion
Irritation hyper-secretion is typically caused by a foreign body on the ocular surface or lashes rubbing on the ocular surface as in trichiasis and entropion
Autonomic abnormalities and pro-secretory drugs like pilocarpine can also cause hypersecretion.
what is the commonest cause of traumatic retinal detachment in children?
traumatic retinal dialysis
what is retinal dialysis
disinsertion of retina at ora serrata
Traumatic dialysis is typically located superonasally
Idiopathic dialysis is typically located inferotemporally
what is the Tx for retinal tears
laser retinoplexy
