Test 28

1. In photometry:

a. troland is a measure of retinal illumination

b. a perfect diffuser reflects all the light which is incident

c. irradiance refers to the amount of light reflected from 
    a surface

d. yellow-green light produces the maximum luminous 
    efficiency 

e. the unit for luminous intensity in common use 
    nowadays is candela

Answer

a.T   b.T   c.F   d.T   e.T
Luminance refers to the amount of light reflected from a surface.

 

2. When light enters from denser to a rarer medium 

a. total internal reflection always occurs 

b. the angle of incidence is equal to the angle of 
    refraction

c. blue light is refracted more than red light

d. it is deviated towards the normal 

e. the speed increases

 
Answer
a. F   b.F   c.T   d.F   e.T
Total internal reflection occurs only when the critical angle is reached. Light with shorter wavelength ie. blue is refracted more than one with longer wavelength ie. red. The light is deviated away from the normal.

3. Following associations are true 

 a. congenital ptosis and astigmatism 

 b. myopia and flat cornea 

 c. myopia and long axial length 

 d. keratoconus and oil droplet reflex on retinoscopy 

 e. congruous hemianopia and cortical lesion 

 
Answer
a.T   b.F   c.T   d.F   e.F
Myopia is associated with steep cornea or long
axial length. Scissoring reflex is characteristic of keratoconus.

4. In an adult patient with ptosis, you will check:

 a. cover test in upgaze 

 b. ptosis maximum in sustained upgaze 

 c. overaction of inferior oblique muscle in lateral gaze 

 d. ask history of contact lens wear 

 e. examination of upper fornix 

Answer
a.F   b.T   c.T   d.T   e.T
Pseudoptosis caused by hypotropia is best detected by the cover test in the primary position.

5. In cases of pupil abnormality, the following examination may
    give you clue to the underlying cause:

a. heterochromia irides 

b. iris examination on the slit lamp 

c. gonioscopy 

d. anterior chamber examination on slit lamp 

e. macular examination with 60D

Answer
a.T   b.T   c.T   d.T   e.F
Heterochromia irides occurs in congenital Horner's 
syndrome and siderosis bulbi. Vermiform movement 
of the iris occurs in Adie's pupil. Gonioscopy may 
detect tumour or intraocular foreign body in the angle of the trabecular meshwork. Anterior chamber 
examination may reveal inflammation, posterior synechia
or previous eye trauma. Macular lesion does not cause pupil abnormality.

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