Test 15

1. In colour vision testing: a. the illumination should be equivalent to the morning daylight in    northern hemisphere b. Farnsworth-Munsell hue 100 test uses 84 coloured discs c. the discs of Farnsworth-Munsell hue 100 tests have the same     brightness and saturation. d. D-15 is a modified Farnsworth-Munsell (FM) hue 100 e. Ishihara is most useful for picking up congenital red-green defect   answera.F   b.T   c.T   d.T   e.T The illumination is the afternoon daylight in the northern hemispheres.     2. Indocyanine green: a. is a fluorescent substance b. absorbs light with a wavelength of 805 nm c. emits infrared light d. is absorbed by the retinal pigment epithelium. e. leaks out of the choroidal circulation readily. answera.T   b.F   c.T   d.F   e.F Indocyanine green emits light of 835nm. It is highly bound to the serum proteins and does not leak out of choroidal circulation or absorbed by RPE making it useful for visualizing choroidal vessels.   3. The following are true about light: a. visible light has a wavelength between 400 to 780nm b. colour of an object is determined by the wavelength     absorbed by its surface. c. red colour has a longer wavelength than green colour d. things appear more blue to aphakic than phakic patient e. blue filter is useful in filtering harmful light to human eye. answera.T   b.F   c.T   d.T   e.F Colour of an object is determined by the wavelength emitted by its surface. Yellow filter is used to filter out harmful light.     4. The following are true about visual testing in children: a. Catford drum usually over-estimates the visual acuity.. b. STYCAR rolling ball test relies on the observation of      the subject's pursuit movement. c. Cardiff cards uses preferential looking. d. Kay's picture tests may be used by children 2 years of age e. five different letters are used in Sheridan-Gardiner test answera.T   b.T   c.T  d.T   e.F Seven letters are used in Sheridan-Gardiner's test.   5. Myopic shift occurs with: a. nuclear sclerosis b. anterior movement of the lens or implant c. flattening of the corneal surface d. use of cycloplegic e. use of pilocarpine. answera.T   b.T   c.F   d.F   e.T Nuclear sclerosis increases the refractive index of the lens and make the eye more myopic. Anterior movement of the lens or implant move the focus point anterior and makes the eye more myopic. Pilocarpine contracts the ciliary muscle making the lens more spherical and therefore more moving the focus point anteriorly and hence myopic shift. Flattening of the corneal surface is use to reduce myopia. Cycloplegia by relaxing the ciliary muscle makes the  lens less spherical and shifts the focal point posteriorly ie hypermetropic shift..   Return to the main page