Test 200  (Ocular pathology)

1. Microaneurysms:

a. are dilatations of the retinal veins

b. can be distinguished from dot haemorrhages 
    by fluorescein angiography

c. are 10mm to 100mm in diameter

d. are usually found in areas of retinal non-perfusion

e. may develop a hyalined wall and appear white

 
Answera.F   b.T  c.T   d.T  e.T
Microaneurysms are dilatations of the retinal capillaries.

2. Cotton wool spots:

a. result from arteriolar occlusion in the nerve fibre layer

b. are usually less than one disc diameter 

c. are found mainly adjacent to the major vascular arcade

d. result from interruption of axoplasmic flow

e. seen in diabetes mellitus tend to persist longer than 
    those in hypertensive retinopathy

 

Answera.T  b.T  c.T  d.T  e.T
Cotton wool spots seen in diabetes mellitus tend
to  persist for 3 to 6 months but those in hypertensive retinopathy tend to disappear after 6 weeks.

3. The following factors are important in angiogenesis in diabetic 
     retinopathy:

a. tissue necrosis factor

b. basic fibroblast growth factor

c. lymphokines

d.  insulin-like growth factor

e. vascular endothelial growth factor

 
Answer
a.F   b.T  c.F  d.T e.T
Three angiogenic factors are thought to be important
in diabetic retinopathy: basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF), and vascular 
endothelial growth factor (VEGF).

 

. 4. Siderosis bulbi:

a. is commonly the result of incompletely removed 
    corneal foreign body containing iron

b. causes miosis which does not respond to light

c. causes iris hyperpigmentation

d. gives an initial supernormal signal in electroretinography
    followed by a progressive decrease in the b-wave 
    amplitude

e. causes subcapsular sunflower cataract

Answer
a.F  b.F  c.T  d.T  e.F
Siderosis bulbi is caused by intraocular foreign body 
containing iron. It causes mydriasis, iris hyperpigmentation,
decreased visual acuity, glaucoma and cataract. The ERG is initially supernormal followed by extinction of the waveforms with time. Sunflower cataract is a feature of chalosis (copper retention).

5. Optic disc drusen:

a. usually contains calcium

b. is associated with age-related macular degeneration

c. is associated with angioid streaks

d. is associated with venous obstruction

e. causes visual field abnormalities

 
Answer
a.T   b.F  c.T  d.T  e.T
Optic disc drusen contains calcium and can be identifiedon CT scan and ultrasound.
Optic disc drusen is different from the drusen found at Bruch's membrane associated with age-related macular degeneration. It is associated with angioid streaks and retinitis pigmentosa. Complications of optic disc drusen include choroidal neovascularization around the optic 
disc, venous obstruction and visual field abnormalities.

 

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