Test 16 1. The following are true about the 3 and 9 O'clock staining
of the cornea:a. they represent areas of poor wetting2. The following are true:
b. they occur in incomplete blink response
c. occur more commonly with gas permeable contact lens
than soft contact lens
d. a lens with greater movement may solve the problem
e. give rise to corneal vascularization if untreated
a. the cornea has more refractive power than the lens3. A Galilean telescope used in low vision:
b. the centre of the cornea is steeper than the periphery in
c. radial keratotomy flattens the cornea
d. hypermetropia can be corrected by steepening the cornea
e. strabismus surgery can induce astigmatism.a. has a plus objective4. The following are true about blurred image resulted from tilted retina:
b. contains a minus eyepiece lens.
c. the distance between the plus objective and the eyepiece is
equal to the sum of the focal lengths of the two lenses
d. produces a virtual image
e. required an image-inverting system.a. the blurred image is the result of astigmatism.
b. it can be corrected with spectacle.
c. it can be corrected with contact lenses.
d. refractive surgery can correct the blurred vision.
e. cataract extraction with implant can sharpen the image5. The following are true about the contact lens:a. Dk values measured the oxygen permeability of a contact lens
b. the oxygen permeability depends on the thickness of the lens
c. rigid gas permeable lens always have a lower Dk than soft
d. PMMA contact lens do not allow oxygen penetration
e. the higher the water content of a soft contact lens the higher
the oxygen transmissibility.
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