Key points 2 Flashcards
What is the maximum advisable resection of MR and LR in esotropia
medial recession: 6 mm
lateral resection: 9 mm
What is the maximum advisable resection of MR and LR in exotropia
medial resection: 10 mm
lateral recession: 10 mm
What are the features of myogenic congenital ptosis?
dysgenesis of the levator muscle complex
the levator complex is atrophic with replacement of muscle fibers by fibrous or adipose tissue
How to treat uveal effusion syndrome?
placement of partial thickness scleral windows near the vortex vein exit sites in at least three quadrants of the eye.
differential diagnosis for posterior ischemic optic neuropathy (PION)
radiation optic neuropathy
status post-coronary artery bypass graft
anaemia
acute systemic hypotension
giant cell arteritis
Features of malignant hypertension
produces posterior segment features such as AV nipping, exudates and haemorrhages
What is incomplete penetrance
In an autosomal dominant (AD) condition, gene carriers may sometimes have few or no signs of the disorder
What is variable expression
The degree or extent to which a disorder manifests in an affected individual
Ultrasound features of a sinus mucocoele with orbital extension
a rounded extraconal lesion with well-defined, smooth borders and very low internal reflectivity.
Ultrasound features of Neurofibromas in the orbit
Well-defined with smooth borders but will have high reflectivity.
Ultrasound features of Lymphangioma in the orbit
irregular borders
Ultrasound features of Metastatic cancer and pseudotumour in the orbit
have irregular borders and high reflectivity.
characteristic features of early-onset (infantile) exotropia
presentation at birth or soon thereafter
normal refraction
large angle
DVD
neurological anomalies frequently present (unlike infantile eso)
Rx: mainly surgery, e.g. LR recess/MR resect
Culture medium for Chlamydia trachomitis
McCoy agar
Facts about the use of topical beta blockers
IOP reduction is better in combination with prostaglandins than CA-inhibitors
they act primarily by reducing aqueous secretion
their IOP-lowering effect is less during sleep
Features of Miller Fisher syndrome
ophthalmoplegia
areflexia
ataxia
Antibodies seen in Miller Fisher syndrome
anti-GQ1b IgG antibodies.
Examples of conditions with Mitochondrial mutation implications?
Leber’s hereditary optic atrophy (LHON) - painless subacute visual loss, with central field defects, abnormal colour vision and optic atrophy
MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke like episodes)
Kearns-Sayre syndrome (KSS)
MERRF (myoclonic epilepsy with ragged red fibres)
MIDD (maternally inherited diabetes mellitus and deafness)
Positive antibodies in MG
anti-muscle-specific receptor tyrosine kinase antibodies
anti-acetycholine receptor antibodies
anti-striated muscle antibodies
Positive antibodies in Lambert Eaton syndrome
anti-calcium-channel antibodies
Features of Mooren’s ulcer
ulceration of the peripheral cornea
circumferential spread and later may spread centrally
undermined leading edge
conjunctival injection
pain may be severe and accompanied by photophobia
autoimmune process likely: immunoglobulin, complement, and plasma cells in conjunctiva
Which part of the brain controls the slow pursuit component?
the parieto-occipital lobe
Which part of the brain controls the saccadic component?
Frontal lobe
Which clinical features of newly diagnosed idiopathic pars planitis is most predictive of the future development of multiple sclerosis (MS)?
The risk of future multiple sclerosis (MS) following a diagnosis of pars planitis exceeds 16%. The risk in studies is greater among patients presenting with retinal vascular sheathing.
Features of asteroid hyalosis
the vitreous bodies freely move with eye movement
the condition is associated with diabetes and hypercholesterolaemia
clinically they appear as white spherical opacities
Drugs that can cause vortex keratopathy?
Fabry’s disease
Drugs
amiodarone
chlorpromazine
chloroquine
indomethacin
meperidine
tamoxifen
Inheritance pattern for Wilson disease
Autosomal recessive
How does sunflower cataract occur in Wilson disease
deposition of copper within the anterior capsule (which is not usually visually significant) and Kayser-Fleischer rings from deposition of copper in Descemet’s membrane.
When does diplopia occur?
two images of the object fall on non-corresponding areas of the retina. When two different objects are simultaneously imaged on the foveas and perceived, visual confusion exists.
Which sub-type of glaucomatous nerve damage is characterized by a shallow saucerised cup and a gently sloping rim?
senile sclerotic
What drugs trigger malignant hyperthermia?
succinylcholine, halothane, enflurane, and isoflurane.
What is the definition of the alpha value
the chance of a Type 1 error, that is the chance of inferring a real difference when there is none. It is the same as the p value.
What is a type 2 error?
chance of inferring no real difference when there is one.
What did the Optic Neuritis Treatment Trial (ONTT) show?
oral steroid therapy offered no improvement in long-term prognosis and had a higher rate of subsequent optic neuritis recurrence.
Differentials for pars planitis
MS
Lyme
Sarcoid
TB
Syphilis
Toxoplasmosis
The most common cause of acquired fourth nerve palsy in adults is:
The trochlear nerve has the longest intracranial course of all the cranial nerves, leaving it especially susceptible to damage from closed head trauma
What is a Mittendorf’s dot
a remnant of the posterior tunica vasculosa lentis and results in a white dot infero-nasally on the posterior capsule of the lens. It is meaningless visually
A patient has noticed xanthopsia, photopsia and pain on eye movements since commencing a recent medication.
Digoxin causes xanthopsia (yellow-blue discoloration of vision) and rarely photopsia and pain on eye movements.
Lyme disease is associated with which dermatologic finding
erythema chronicum migrans
What are some features of familial exudative vitreo-retinopathy (FEVR)
FEVR is an autosomal dominant trait so a family history would be expected, and presentation is usually in early childhood with disc dragging and severe visual loss.
What tests may differentiate optic neuropathy from amblyopia?
brightness sense: diminished in ON, not amblyopia
colour vision: diminished in ON, not amblyopia
neutral density filters: reduce vision in ON, increase vision in amblyopia
visual fields: affected in ON, full in amblyopia
two histological features commonly seen in benign hypertension
hyalinization and intimal proliferation of the muscular media of the medium sized arteries and arterioles
What is the Hirschberg’s method for estimating the angle of strabismus
Each millimeter of decentration is roughly 7 degrees of deviation. Each degree is approximately 2 prism diopters. Thus, each millimeter is approximately 15 prism diopters. Three millimeters is 21-plus degrees, or 45 prism diopters.
What are Elschnig spots?
choroid and RPE infarct: grey-black spots surrounded by a yellow ring
differential of a dilated pupil
traumatic mydriasis
Adie’s pupil
third nerve palsy
pharmacologic dilation
What is the primary action of IO muscle
extortion which is isolated at 39 degrees abduction
Which cancer syndrome has AR inheritance
Ataxia telangectasia.
Which fundus finding would be MOST suggestive of Leber’s hereditary optic neuropathy
In the acute phase, the optic nerve in LHON is hyperaemic and swollen with telangiectatic capillaries. The nerve does not leak on fluorescein angiography. Later stages may only manifest optic atrophy.
What are the Guidelines for ocular screening in JIA
systemic onset: no screening
poly-articular onset: every 9 months
poly-articular onset with ANA positive: every 6 months
pauci-articular onset: every 3 months
pauci-articular onset with ANA positive = every 2 months
Differential diagnoses for VKH
infectious choroidal infiltration: e.g. TB, syphilis
tumour infiltration of choroid
posterior scleritis
sympathetic ophthalmia
hypotony
uveal effusion syndrome
lupus choroidopathy
Epidemiological characteristics of patients with NTG
patients are more likely to have a family history of POAG than the normal population
patients tend to be older than those with POAG
it occurs more frequently in Japan than in Europe
females are at greater risk than males
Microbiological causes of Reiter’s syndrome
Post-urethritis
Ureaplasma urealyticum
Chlamydia trachomatis
Post-dystentry
Shigella
Salmonella
Yersinia
Most common causes of intermediate uveitis
Pars planitis (the most common, a diagnosis of exclusion)
Sarcoid
MS
Lyme
Types of cataract in various conditions
Atopic dermatitis anterior subcapsular shield cataract. Wilson’s disease sunflower cataract;
myotonic dystrophy Christmas tree cataract and later with stellate posterior subcapsular cataract;
neurofibromatosis-2 with posterior cortical cataract.
What are the Initial treatment options for primary congenital glaucoma
goniotomy
trabeculotomy
medical therapy
Trabeculectomy may be an option, but given that these young patients tend to heal exuberantly, its success may be limited and it (plus or minus tubes) is usually only considered after attempts at goniotomy and trabeculotomy have been attempted.
What is the purpose of the prism adaptation test
involves prescription of corrective prisms prior to undertaking muscle surgery in order to determine whether the patient can achieve sensory fusion with alignment.
Characteristics of retinoschisis
Snow-flakes and silver-wiring of blood vessels on the retinal surface. Retinoschisis is also relatively immobile compared to RD
Why are topical alpha 2 agonists avoided in children?
The alpha-2 agonists (apraclonidine and brimonidine) should be avoided in children because they have the potential to cross the blood-brain barrier.
What is CHED (Congenital hereditary endothelial dystrophy)?
occurs secondary to a defect of the corneal endothelium and Descemet’s membrane. The corneal oedema present may resemble that seen in congenital glaucoma, but there is no elevation in IOP or increased corneal diameter.
NS vs PSC cataract symptoms?
A 78-year-old man complains of difficulty driving caused by decreased distance vision. This history is most consistent with nuclear sclerosis. In contrast, patients with posterior subcapsular cataract will notice difficulty primarily with reading vision, particularly in bright ambient lighting.
Features of progressive cone-rod dystrophy
Presentation is usually in the first or second decades with reduced central vision. Foveal granularity progressing to a Bull’s eye maculopathy is typical. Mid-peripheral bone-spicule pigmentation, arteriolar attenuation and waxy disc pallor may also develop. ERG shows reduced photopic responses and flicker fusion frequency with rod responses relatively preserved. EOG is normal to subnormal. Colour vision is usually reduced out of proportion to visual acuity.
What is NOT an indication for strabismus surgery in intermittent distance exotropia?
An increasing angle on prism cover test is not in itself an indication for surgery if the patient is able to comfortably control the angle.
What are indications for strabismus surgery in intermittent distance exotropia?
An increased frequency of breakdown to diplopia, loss of stereopsis and abnormal head postures are all indications for surgery.
Which treatment is most likely to be effective in controlling ICE syndrome glaucoma?
Glaucoma is difficult to control in ICE syndrome, even with surgical trabeculectomy which is prone to bleb failure. Artificial filtering shunts are the definitive treatment and are required for effective pressure control in many cases.
What were the study goals of the Collaborative Corneal Transplant Study?
a set of multicenter trials that investigated the efficacy of matching the donor-recipient HLAs on the incidence of graft rejection and graft survival in high-risk recipients undergoing penetrating keratoplasty
In terms of HLA Matching, what were the conclusions of the Collaborative Corneal Transplant Study
HLA-A, HLA-B, and HLA-DR matching the donor and recipient had no effect on overall graft survival
Allowing 5 minutes between two eye drops works on the principle of
pharmacokinetics
What is Gradenigo’s syndrome
caused by localised infection or inflammation of the petrous apex. Features include trigeminal neuralgia (5th nerve), sixth palsy, seventh palsy and otitis media.
What describes the standard deviation?
it is a measure of the spread of the sample distribution
What condition is retinal haemangioblastoma associated with?
Von Hippel Lindau syndrome
What are some features of VHL
causes exudation, bleeding, leakage and even retinal detachment.
