Key points Flashcards
Phakic eye with silicone oil induces what refractive error?
hyperopic shift usually between 5-9 dioptres
Aphakic eye with silicone oil induces what refractive error?
myopic shift
What is the prevalence of contralateral FTMH in patients with established MH
The prevalence of bilaterality of idiopathic macular holes, including earlier stages before a full-thickness dehiscence develops, will be higher, approaching 20% to 25%. Because a large proportion of early holes spontaneously resolve, only a small fraction (5%) develop bilateral full-thickness defects.
What type of lenses does the panfundoscope lens consist of?
2 convex lenses
When doing IO, is the 20D lens held further or closer to the patient than the 30D lens?
Further away
Which drug is SJS associated with mainly?
Sulphonamides
Diagnosis? A patient with a history of recurrent haematuria has increasing myopia, anterior lenticonus and macular flecks.?
Alport syndrome
Histopathological findings in Alport syndrome?
a defect in Type 4 (basement membrane) collagen
Features of Alport syndrome?
1) glomerular basement membrane nephritis
2) anterior lenticonus
3) cortical cataract
4) posterior polymorphous dystrophy
5) dot-fleck retinopathy
Inheritance pattern of Alport syndrome?
X-linked recessive (80%) and X-linked dominant (5%) forms
Congenital Causes of Ectopia Lentis
Familial
Aniridia
Marfan’s
Homocystinuria
Weill-Marchesani
Hyperlysinaemia
Sulphite oxidase deficiency
Stickler’s syndrome
Ehlers-Danlos syndrome
Acquired causes of Ectopia Lentis
Trauma
Large eye (myopia, buphthalmos)
Anterior uveal tumours
Hypermature cataract
In severe TB, what proportion of patients is the Mantoux test negative in?
50%
POAG risk factors?
elevated IOP
positive family history of glaucoma
myopia
diabetes mellitus
cardiovascular disease
African American race
asymmetric cupping
large cups
early nonspecific visual field changes
thin corneas
What is the surface tension of silicone oil like in comparison to all the gases?
Significantly less than all gases
Features of lateral medullary syndrome?
ipsilateral vestibular nuclei symptoms (vertigo, nausea, nystagmus)
ipsilateral cerebellar signs such as dysdiadokinesia and dysmetria
lateral spinothalamic tract damage causing contralateral pain and temperature sensation loss
spinal trigeminal nucleus damage causing ipsilateral facial paraesthesia
ipsilateral Horner’s
ipsilateral bulbar signs such as hoarseness and dysphagia
Features of Terrien’s marginal degeneration
an uncommon, idiopathic, non-inflammatory condition
male preponderance
typically bilateral
peripheral corneal thinning
occurs superiorly first, then circumferentially
intact epithelium in an essentially quiet eye (unlike Mooren’s ulcer or PUK)
peripheral gutter: outer slope shelves gradually, central slope rises sharply
separated from limbus by clear zone
perforation is rare
against-the-rule astigmatism is often induced (flattening in the vertical meridian)
pseudo-pterygia can develop in longstanding cases
Treatment: rigid gas-permeable contact lens; crescentic patch graft in severe cases
Features of Parinaud’s dorsal midbrain syndrome?
light-near dissociation
mydriasis
Collier’s sign (lid retraction in primary position)
paralysis of convergence and accommodation
paralysis of upgaze (supranuclear palsy)
convergence-retraction nystagmus (worsened by upward rotation of OKN drum)
skew deviation
papilloedema or optic atrophy (if ventricular flow compromised)
Commonest cause of Parinaud’s Dorsal Midbrain Syndrome?
infants: hydrocephalus
young children: pinealoma
young adults: head trauma and multiple sclerosis
older adults (60 years): stroke
What is ICE syndrome?
caused by an abnormal corneal endothelial cell layer which proliferates and migrates across the angle and onto the iris
Commonest complication of ICE syndrome?
Glaucoma occurs in about 50% of cases, due to synechial angle closure secondary to contraction of this abnormal tissue.
What is thought to cause ICE syndrome?
PCR suggests a possible herpes simplex viral origin to the disease process.
Focal lymphoid aggregates in the substantia propria of the conjunctiva are otherwise known as:
Conjunctival follicles represent focal lymphoid aggregates in the substantia propria.
Follicles vs papillae?
The central part of the follicle is avascular, but dilated blood vessels may surround the base and sweep up from the base over the convexity
Papillae are vascular changes most prominent on the palpebral conjunctiva and the limbus; sites where fibrous septa anchor the conjunctiva to the underlying tissues. In contrast to follicles, papillae have a dilated vascular core surrounded by oedema and a mixed inflammatory infiltrate producing raised elevations of the conjunctival epithelium.
What are features of Plateau iris configuration?
Shallow iridocorneal angle due to anterior rotation of ciliary processes
AC depth NORMAL
Iris plane flat as opposed to convex in usual normal angles
Common in South East Asians than whites
Glucocorticoid with highest systemic potency?
dexamethasone, methylprednisolone, prednisolone, hydrocortisone, cortisone.
Features of PORN
caused by varicella zoster virus
occurs predominantly in immunocompromised individuals
presentation is initially unilateral
Features of Prednisolone
cytostatic anti-inflammatory agent that is a nonspecific immunosuppressive.
According to the Silicone Study, what is the rate of retinal re-detachment after removal of silicone oil in the setting of proliferative vitreoretinopathy
The Silicone Study compared the efficacy of silicone oil to C3F8 and SF6 in the treatment of proliferative vitreo-retinopathy. It found silicone oil to be superior to SF6 and equally effective to C3F8. The rate of re-detachment was 20% after removal of silicone oil.
Marfan’s syndrome is caused by a defect in:
Fibrillin
Ehler Danlos syndrome is caused by a defect in:
defective Type 1 (or Type 3) collagen
Stickler syndrome is caused by a defect in:
defective Type 2 (or Type 9) collagen
Alport syndrome is caused by a defect in:
defective Type 4 collagen
Features of Ghost cell glaucoma
vitreous haemorrhage (red blood cells degenerate and become rigid in the vitreous) and a break in the anterior hyaloid face (to allow the cells to enter the anterior chamber). The khaki-coloured ghost cells layer out in the anterior chamber and can be distinguished from fresher red cells, creating the effect of a candy stripe.
Difference between haemolytic and phacolytic glaucoma?
haemolytic glaucoma, haemoglobin-laden macrophages block the meshwork, while in phacolytic glaucoma, macrophages are engorged with lens protein from a hypermature cataract.
Features of Birdshot chorioretinopathy
idiopathic, chronic, recurrent bilateral disease.
affects females more than males, and occurs in the fifth to seventh decades
insidious impairment of vision, floaters, photopsia and night blindness
Signs include mild to moderate vitritis (without snowballs or snowbanking), retinal vasculitis and multiple, small ill-defined cream-coloured choroidal spots. Old scars are well-delineated atrophic spots, with no tendency to become hyperpigmented
What % of patients are HLA-A29 positive in Birdshot Chorioretinopathy
95% of patients are HLA-A29 positive
When is a paired t- test useful?
The paired t-test is appropriate when we obtain pairs of results on only one variable of interest
The differences between pairs of observations should be normally distributed.
What ocular structures are derived from Neuroectoderm?
retina - neurosensory and RPE
epithelial lining of iris and ciliary body
optic nerves
What ocular structures are derived from Surface ectoderm
lens
corneal epithelium
conjunctival epithelium
lacrimal gland
nasolacrimal system
Meibomian glands
What ocular structures are derived from Neural crest cells
sclera
iris stroma
cornea: stroma and endothelium
TM and Schlemm’s canal
extraocular muscle
ciliary muscle
connective tissue and bony structure of the orbit
What ocular structures are derived from Mesoderm
extraocular muscles
endothelial lining of blood vessels of the eye
blood vessels in sclera and choroid
sclera
vitreous
suspensory fibres
angle outflow apparatus
Which chromosome codes Red and Green cones
X chromosome
Which Chromosome code Blue cones
7
Commonest location for adnexal dermoid cyst
Superotemporal orbital rim in association with the zygomaticofrontal suture line
Systemic features of Behcet disease?
acne
erythema nodosum
aphthous ulcers
genital ulcers
interstitial lung changes
pulmonary artery aneurysm (pathognomonic finding)
Treatment for Behcet disease?
systemic and periocular corticosteroids. Colchicine may be useful in reducing recurrences of the disease. Cyclosporine and cytotoxic agents may also be required.
Hypopyon features of HLAB27 uveitis vs Behcet
The hypoyon in HLA-B27 disease is fibrinous and immobile, in contrast to Behcet’s disease where the hypyon is mobile and often occurs in a relatively white eye.
Histological finding in Optic nerve sheath meningioma?
Psammoma bodies
Features of LCA
the ERG is typically non-recordable at birth
the fundus examination is typically normal at birth
the infant is typically blind at birth
Most forms of Leber’s congenital amaurosis are autosomal recessive.
Features of an image formed by a thin concave lens
virtual, erect, diminished, inside F2
Where is the brain lesion if a right handed man presents with a left homonymous hemianopia without sparing of the macula.
lesion of his non-dominant parieto-occipital lobe.
Features of microtropia
small angle manifest deviation less than 10PD
central suppression scotoma
eccentric fixation
abnormal retinal correspondence
anisometropia common - often hypermetropia +- astigmatism
stereopsis reduced
amblopia
Rx: refractive correction, occlusion for amblyopia
What is microtropia with identity?
the deviation is associated with eccentric fixation which is coincident with the angle of abnormal retinal correspondence so no manifest deviation is detected.
The visual acuity is usually reduced and a BSV is demonstrable.
What is microtropia without identity?
When a very small manifest deviation is seen on cover test. The eccentric fixation is not coincident with the angle of abnormal retinal correspondence.
Features of Wyburn Mason syndrome
sporadic condition
retinal racemose angioma
ipsilateral intracranial AVMs of midbrain, basofrontal regions and posterior fossa
orbital AVMs may also occur (and consequent ocular bruits)
what is the definition of 1PD of power?
that which produces a linear apparent displacement of 1cm of an object 1 m away.
A displacement of 2cm therefore represents a power of 2 dioptres.
Why can macula sparing occur in occipital stroke?
the occipital pole may have a dual blood supply between the posterior and middle cerebral arteries, which may explain the macular sparing phenomenon.
Features of Alport Syndrome
X-linked recessive (80%) and X-linked dominant (5%) inheritance patterns
defect in Type IV basement membrane collagen
renal failure secondary to glomerular dysfunction
megalocornea
posterior polymorphous dystrophy
anterior lenticonus
anterior sub-capsular cataract
corneal arcus
peripheral retinal flecks
sensorineural deafness
Features of Rhabdomyosarcoma
Rhabdomyosarcoma is a very rare disorder but it is an important differential in childhood, sudden-onset, painful, unilateral proptosis. The peak incidence is age 7-8 years and CT findings a non-enhancing, poorly defined mass of homogenous tissue density.
Features of PAM
unilateral condition
occurs in middle age
affects fair-skinned individuals
proliferation of conjunctival epithelial melanocytes
features: irregular, uni- or multi- focal flat brown pigment over any part of conjunctiva
with or without cellular atypia
with atypia: 50% chance of invasive malignancy in 5 years
excision biopsy should be performed on any suspicious nodular lesions
Treatment:
without atypia: does not require treatment
with atypia: excision +- cryotherapy +- MMC
Why are anterior sclerotomies are indicated at the time of surgery in nanophthalmic eyes?
Reduce chance of uveal effusions
Features of Kearns Sayre syndrome
mitochondrial inheritence
ragged red fibres on muscle biopsy
presentation in 1st or 2nd decades
ptosis
external ophthalmoplegia
cardiac conduction defects
deafness
diabetes
short stature
mild pigmentary retinopathy
Most important brain nuclei for generation of normal vertical eye movements
rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) and the interstitial nucleus of Cajal (INC). The PPRF also has a lesser role
Causes of hyperpigmented trabecular meshwork
pseudoexfoliation
pigment dispersion
previous inflammation, trauma or surgery
uveal melanoma
Examples of gram negative rod bacteria
Haemophilus
Pseudomonas
Brucella
E. coli
What is oculomotor apraxia
an inability to initiate voluntary horizontal saccades
What is reverse heterochromia?
where the affected eye becomes more pigmented, may occur in blue eyes, where iris stromal atrophy allows the posterior pigmented layer to show through.
What deposits possess apple-green birefringence
amyloid deposits
Features of bifocal glasses
they are used in the management of convergence excess esotropia
the executive type may be used in the treatment of accommodative spasm
decentration of the reading segment can be used to treat diplopia for near
Liver enzyme inducers?
phenobarbitone
rifampicin
primidone
carbamazepine
Among the phakomatoses, which ones are unilateral glaucoma seen in?
Sturge-Weber syndrome (25% of cases, often associated with an angioma on the upper lid)
von-Recklinghausen’s syndrome (especially if plexiform neurofibroma of the upper lid)
von Hippel-Lindau disease
What urine features are found in GPUT deficiency
Reducing substances
Differentials for uveitic glaucoma
sarcoidosis, zoster, Fuchs’ iridocyclitis, and rarely toxoplasma, syphilis, and sympathetic ophthalmia (SO)
Which are appropriate histopathological stains for calcium
Von Kossa stains calcium black. Alizurin red can also be used, and stains calcium red.
Commonest tumour of the lacrimal gland
Pleomorphic adenoma
Conditions associated with seizures?
neurofibromatosis
Sturge-Weber syndrome
tuberous sclerosis
Features of Kawasaki disease
fever lasting over 5 days
injected pharynx
lymphadenopathy
bilateral conjunctivitis
mucous membrane fissures
strawberry tongue
desquamating rash of palms and soles
non-specific rash
complications: coronary artery aneurysm
Treatment: aspirin
Choristoma vs Hamartomas
Choristomas represent normal tissue in an abnormal location, e.g. dermolipomas and dermoids.
Hamartomas represent abnormal growth of tissue in its normal location, e.g. haemangiomas and lymphangiomas.
Causes of unilateral superonasal masses in the orbit
rhabdomyosarcoma (needs to be excluded)
myocele
mucopyocele
encephalocoele
neurofibroma
Risk factors for ocular involvement in JIA
ANA positive
rheumatoid factor negative
pauciarticular type (90% of cases)
female
involvement of lower extremity joints
lack of involvement of the wrists
early age of disease onset
What is the correlation between prism dioptres and apex angle?
A prism of 1 prism dioptre (Δ) has a refracting angle (α) of 1 ° and an angle of apparent deviation θ of 1/2 ° (half a degree)
Thus a glass prism of apical angle 10 degrees deviates light through 5 degrees and has a power of 10 prism dioptres
In congenital nasolacrimal system obstruction, where is the most common site of obstruction?
Valve of Hasner
Capillary Haemangioma vs Cavernous Haemangioma in terms of blood flow?
Capillary haemangiomas are high-flow lesions, in contrast to cavernous hemangiomas, which are haemodynamically low-flow.
Characteristics of Capillary Haemangioma?
appear a short time after birth
composed of blood vessels that have an abnormal growth proliferation
can be superficial or deep in the orbit
capillary haemangiomas are characteristically high flow lesions
majority: spontaneous involution
70% will resolve before 7 years of age
Follicular conjunctivitis is typically more severe inferiorly than superiorly EXCEPT in which condition?
Trachoma
Conditions where follicular conjunctivitis is seen more severely inferiorly?
inclusion conjunctivitis, Toxic follicular conjunctivitis secondary to medications and viral keratoconjunctivitis are also more severe inferiorly.
How does topiramate induce angle closure glaucoma?
Topiramate can produce a secondary acute-angle closure glaucoma, which is typically bilateral. The proposed mechanism of myopia and secondary angle closure is choroidal effusion and forward rotation of the iris-lens diaphragm.
A 10 degree rotation of a toric IOL reduces the astigmatic effect of the lens by:
30%
How eye problems are associated with Goodpasture’s syndrome?
anti-basement membrane antibody. retinal and choroidal vasculitis can occur.
Features of basic exotropia
exotropia equal at distance and near
Features of Convergence-insufficiency exotropia
exotropia greater at near
Features of Divergence-excess exotropia
exotropia greater at distance than near
What is the 20 PD base out test?
The normal movement when a 20-dioptre base-out prism is placed in front of an eye is for both eyes to move towards the apex of the prism, followed by an adduction movement of the fellow eye to take up binocular fixation
What are the findings when a dense monocular visual impairment is present with 20PD BO test?
one would expect no movement of the eyes when the prism is placed in front of the affected eye.
Which children’s acuity test would be best at detecting reduced acuity in amblyopia?
The Sonksen-Silver acuity test, unlike the other options, provides crowded letter optotypes. Crowding is useful as it is a more sensitive test for amblyopia (i.e. it will detect reduced visual acuity in an amblyopic eye more readily) compared to a single optotype.
Characteristic ERG findings in AZOOR
reduced a-wave and b-wave amplitude and delayed 30 Hz flicker
