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.
