Key Points 6 Flashcards
When is a Jones tube indicated?
cases in which the canalicular system is disrupted and is inadequate to allow tear flow into the nose. In certain situations, even a patent canalicular system may require a Jones bypass conduit if the lacrimal pump mechanism is disrupted (scarred or paralytic lids). A canaliculodacryocystorhinostomy is indicated for a focal distal canalicular obstruction combined with nasolacrimal duct obstruction.
In acquired nasolacrimal system obstruction, where is the blockage most frequently located?
most frequently at the level of the mid or lower duct.
What are some features of PCV (polypoidal choroidal vasculopathy)
PPCV is more common in pigmented patients (e.g. Asians) where it accounts for up to 20-50% of patients with presumed exudative AMD. PPCV also occurs in Caucasians, where it may account for 5-12% of presumed cases of exudative AMD. PPCV is characterised by a branching vascular network with polypoidal lesions at the borders, and is best visualized with ICG. It is more commonly unilateral, and is more commonly associated with sub-retinal haemorrhages and pigment epithelial detachments compared to exudative AMD. It is generally accepted that PCV has a better visual prognosis than typical neovascular AMD, as progression is slow and subretinal fibrous proliferation is unusual. However, the visual prognosis is variable over its natural course. Treatment is with anti-VEGF and PDT.
Which IOFB are tolerated best and worst?
Inert foreign bodies such as glass, plastic, sand and ceramic are relatively well tolerated. Both iron and brass (which contains copper) can cause inflammation and retinal degeneration. Wood incites a brisk inflammatory response and may harbor microorganisms.
What is Crede’s prophylaxis or silver nitrate
s used to prevent infectious conjunctivitis in the neonate can itself cause a conjunctivitis presenting within 24 hours of birth (medicamentosa). Treatment with mild topical antibiotics, or no treatment at all, is sufficient.
The other causes of neonatal conjunctivitis listed above all require systemic treatment:
Chlamydia = oral erthromycin
HSV = i.v. aciclovir
Gonnorhoeae = i.v. penicillin
Which of the following findings is NOT in keeping with an acute, sub-total rhegmatogenous retinal detachment:
An acute, rhegmatogenous retinal detachment typically presents with a dome-shaped elevation and a corrugated retinal surface from intra-retinal oedema. A smooth retinal surface suggests an exudative retinal detachment.
Which landmark clinical trial assessed the efficacy of pegaptanib in treating neovascular age-related macular degeneration?
The VISION trial assessed the efficacy of pegaptanib in treating neovascular AMD.
What are some features of SO
occurs in less than 0.1% of cases of penetrating injury. It results in bilateral granulomatous panuveitis. Treatment is with steroids and immunosuprressants. Once inflammation has settled, the role of enucleation of the inciting eye in reducing inflammation is controversial.
What kind of corneal ulcers are common in vernal disease?
shield ulcers, which are large oval, central epithelial defects
What colour colonies does Candida appear like in agar?
In agar, macroscopic colonies of Candida appear white.
Six prism diopters of left esotropia are best corrected by:
3 dioptres base-out left eye, 3 dioptres base-out right eye
What are features of Weill Marchesani syndrome?
Features of Weill-Marchesani include:
Systemic
short stature
brachydactyly
stiff joints
mental handicap
Ocular
bilateral, inferior ectopia lentis
spherophakia or microspherophakia
angle anomaly
pre-senile vitreous liquefaction
What are Lacquer cracks and when are they seen?
High myopia is characterised by lacquer cracks (not angioid streaks). Lacquer cracks represent breaks in the RPE-Bruch membrane-choriocapillaris complex.
What vitamin supplementation is required for a patient with pernicious anaemia-related optic neuropathy?
Pernicious anaemia is an auto-immune disease where loss of parietal cells in the gastric lining causes malabsorption of vitamin B12.
What is the primary abnormality in simple congenital ptosis
Congenital ptosis is typically myogenic. It is caused by maldevelopment isolated to the levator-superior rectus complex.
Infection with which pathogen is characteristically associated with an owl-eye inclusion body:
Owl-eye inclusion bodies are characteristic of cytomegalovirus infection as seen for example in cytomegalovirus retinitis in immunocompromised patients.
ERG findings in Stargadts disease?
Full field ERG in fundus flavimaculatus (Stargardt’s) is typically normal and only the focal macular ERG is abnormal; only in advanced disease do the photopic and scotopic ERG’s become abnormal.
Features of RP?
1:3500 incidence
50% sporadic
50% inherited: 22% AD, 16% AR, and 9% X-recessive
X-linked most severe form
ERG abnormalities precede signs and symptoms
Early ERG: normal cone response, decreased scotopic b-wave
Late ERG: nonrecordable ERG
Early VF: inferotemporal scotoma
Late VF: ring or annular scotoma
Findings: attenuation of the retinal vessels, midperipheral pigmentary changes, and optic disc pallor
Associations: include myopia, vitreous opacities, posterior subcapsular cataract, retinal pigment epithelial atrophy, cystoid macular oedema, glaucoma, and keratoconus
What is Bruckner testing
is a bilateral red reflex test, and if strabismus is present the brighter reflex is in the deviated eye. This is because the light reflects from peripheral retina in the deviated eye; and since there is less pigment in the peripheral retina than the macula, there is more reflection of light from the peripheral retina of the deviated eye.
What is the incidence of retinal detachment in fellow eyes of patients with giant retinal tears?
Patients with a giant retinal tear in one eye have a very high risk (50%) of retinal detachment in the fellow eye.
What are the refractive indices of various lens IOL materials?
The refractive indices of popular lens materials are:
PMMA = 1.49
Silicone = 1.41- 1.46
Hydrophobic acrylic =1.54
Hydrophilic acrylic = 1.47
A higher refractive index means the lens can be made thinner for an equivalent power.
What is the most common cause of re-detachment following initially successful surgical repair of rhegmatogenous retinal detachment?
Proliferative vitreoretinopathy (PVR) is the most common cause of re-detachment after successful repair. Retinal pigment epithelium (RPE) and glial cells proliferate and subsequently contract, causing fixed folds, traction, and/or detachment.
What are some features of pterygium?
wing-shaped folds of conjunctiva and fibrovascular tissue
aetiology unknown
UV exposure is a risk factor
advancing fibrovascular tissue including destruction of Bowman’s layer (corneal scarring)
changes in corneal astigmatism often occur: flattening in the involved meridian
may become inflamed with dellen formation
iron deposition at the leading edge is called Stocker’s line
treatment: observation or excision
high recurrence rate
recurrence lowered by: conjunctival autograft, amniotic membrane graft and MMC
What is the function of Dacryoscintigraphy?
Dacryoscintigraphy provides functional rather than anatomical information and is useful when syringing appears patent. Unlike contrast dacryocystography, no pressure is required to inject contrast through the inferior canaliculus which can overcome a functional occlusion. CT and MR dacryocystography involve topical instillation of contrast on the conjunctiva rather than injection through the canaliculus. The anatomical details are good in both methods however the functional data is not as good as dacryoscintigraphy.
What are the features of APMPPE?
lesions are larger than those found in MEWDS
active lesions are replaced by variable RPE changes after 2-6 weeks
placoid lesions begin at the posterior pole before spreading toward the equatorial fundus
What is the mode of action of sulfadiazine:
blocks the production of dihydrofolate from para-aminobenzoic acid
In a patient with a trabeculectomy bleb, which signs may occur in both endophthalmitis and blebitis:
Blebitis is an infection localised to a trabeculectomy bleb, although there is a risk of intraocular spread to cause endophthalmitis. Discriminating between the two is important for clinical management. Blebitis may be treated with topical antibiotics with or without steroid cover, while endophthalmitis requires an intravitreal tap and intravitreal antibiotics. In both endophthalmitis and blebitis, there is a milky white infected bleb, which is the source of the infection. However, with endophthalmitis there is associated loss of vision, loss of red reflex, significant AC reaction with hypopyon and vitritis.
Causes of autofluorescence of the optic disc:
optic disc drusen
astrocytic hamartomas
What are the orbital features of patients with craniosynostoses?
shallow and small, with resultant proptosis and exposure. V-pattern exotropia is also common.
Examples of Craniosynostoses conditions?
Crouzon’s, Apert’s and Pfeiffer’s syndromes
What are the features of Reis Buckler corneal dystrophy?
autosomal dominant inheritance
also known as granular type 3 dystrophy
a progressive dystrophy
lesions occur at the level of Bowman’s layer and anterior stroma
histopathology shows replacement of Bowman’s layer by a fibrocellular tissue
stains with Masson trichrome
symptoms arise in adulthood: recurrent erosions and decreased vision
Treatment: superficial keratectomy, excimer laser phototherapeutic keratectomy, or penetrating keratoplasty
Recurrence in the graft is very common
What are corneal features of spheroidal degeneration?
Spheroidal degeneration (also known as corneal elastosis, Labrador keratopathy, climatic droplet keratopathy or Bietti nodular dystrophy) is characterised by:
bilateral condition
more common in men
usually asymptomatic but vision loss may occur
proteinaceous deposits in the superficial stroma with replacement of Bowman’s layer
sunlight is a risk factor
treatment: UV protection, superficial keratectomy and lamellar keratoplasty in severe cases
A patient has an optic disc pit and an adjacent retinal detachment temporal to the disc. The patient is asymptomatic and the visual acuity is 6/6.
What is the most appropriate management?
Patients with optic disc pit-associated neurosensory detachment can be observed. Up to one quarter of patients have spontaneous resolution of retinal deachment. Laser photocoagulation can be considered if the VA is affected. Pars plana vitrectomy with gas tamponade can be performed if laser fails.
What proportion of patients with myasthenia gravis will develop Graves’ disease?
5% of MG patients develop Graves disease, so the condition should be screened for during work-up. A tiny fraction of patients with Graves’ disease will develop myasthenia gravis as well.
Which medication is most commonly used in cases of filamentous fungal keratitis caused by Fusarium spp?
Natamycin is a polyene antifungal that is the treatment of choice for filamentous fungi.
Which procedure is most likely to result in post-operative infectious scleritis?
Pterygium surgery with beta radiation or application of mitomycin C has been identified as a common risk factor for infectious scleritis.
The entity in the differential diagnosis with spasmus nutans that must be ruled out is:
parasellar gliomas
What are the features of MEWDS?
MEWDS typically presents with shimmering photopsias and paracentral scotomas. These scotomas often correspond to an enlarged blind spot on visual field testing. Fundus fluorescein angiography (FFA) shows early punctate hyperfluorescence with late staining of the lesions arranged in a “wreath-like” configuration around the fovea. The condition is usually self-limiting with recovery in 4 to 10 weeks.
What are Touton cells
fusion of epithelioid cells (macrophages) with nuclei surrounded by foamy cytoplasm.
Which condition is most likely to present with peripheral retinal neovascularisation?
Incontinentia pigmenti presents with vascular abnormalities in the peripheral retina including capillary non-perfusion, AV shunts, fibrovascular proliferation, and neovascularisation, which may progress to retinal detachment.
Why are steroids contraindicated in Kawasaki disease?
increased risk of coronary aneurysm formation.
A patient receives an intra-dermal injection of purified protein derivative of Mycobacterium tuberculosis. After 48 hours, there is an area of induration 17mm in diameter.
What does this result suggest:
This is a tuberculin test. An area of induration >15mm is a strongly positive result and suggests active disease. A weakly positive test is difficult to distinguish active disease from previous exposure or immunization. A negative result usually excludes TB but may occur in comsumptive disease.
What type of lens opacity might develop in patients with AACG?
Acute angle closure glaucoma may cause small, grey-white, anterior, capsular or subcapsular opacities within the papillary area, which are known as glaukomflecken.
What does the term ‘inactive uveitis’ means according to the Standardization of Uveitis Nomenclature (SUN) Working Group?
According the SUN working group, inactive uveitis is classified as Grade 0 cells.
What are fluorescein angiography findings typical of APMPPE
Fluorescein angiography in active APMPPE typically shows early dense hypofluorescence associated with non-perfusion of the choriocapillaris and late hyperfluorescence due to staining. ICG will also demonstrate (more clearly than FA) non-perfusion of the choriocapillaris.
Which of the white-dot syndromes does NOT cause vitritis?
PIC does not cause intraocular inflammation. APMPPE and serpiginous choroidopathy cause mild vitritis, while birdshot causes moderate vitritis.
Which radiographic feature is considered pathognomonic for optic nerve glioma?
In ON glioma, the optic nerve is variably enlarged, and the mass may either be fusiform or exophytic in appearance. Additionally the nerve may be elongated with kinking or buckling.
Which radiographic feature is considered pathognomonic for optic nerve meningioma?
tram-tracking is considered classic for optic nerve sheath meningioma.
The most common fundus finding in a patient with acute traumatic optic neuropathy is:
Disc oedema, disc haemorrhages, and choroidal rupture are all potential signs of acute traumatic optic neuropathy, but the most common finding is a normal fundus. Disc pallor does not occur in the acute setting but is present in all cases after several weeks.
Which materials may be used for frontalis suspension of the eyelid
donor fascia lata
autogenous fascia lata
temporalis fascia
supramid
silicone
Gore-Tex
The second most frequently involved extraocular muscle in Graves’ ophthalmopathy is the:
In descending order from most to least frequently involved in TED:
inferior rectus
medial rectus
superior rectus
lateral rectus
NOTE: remember the pnemonic I M Stuart Little
Features of Coat’s disease?
idiopathic, non-hereditary occurrence
retinal telangiectasis
intraretinal and subretinal exudation
exudative retinal detachment (two-thirds of cases)
males > females
bimodal with most presenting in childhood before age 10 yrs
presenting signs: leucocoria, strabismus, reduced vision,
90% unilateral
treatment with Argon laser if progressive exudation or VR if detachment
