Refraction and Orthoptics

Question 1

VA tests

Answer 1

forced choice preferential looking
cardiff cards: pics
logMar Kay: matching pictures if talking
Keeler crowded/uncrowded: reading letters; crowded harder
LogMar: same spacing and number each line

Question 2

definitions

Answer 2

EMMETROPIA: optically perfect eye (cornea 40D, lens 20D, length 22.22mm) » accurate focus of light on fovea
AMETROPIA: one or more parameters imperfect » optical/focusing errors
ANISOMETROPIA: difference >2D between eyes
AMBLYOPIA: reduced vision in an eye after refractive/obstructive pathology corrected
HYPER: short length/weak
MYOPIA: long/strong
ASTIGMATISM: non-spherical

Question 3

ambylopia

Answer 3

low VA after refraction corrected
critical period (7y): occlusion

squint, refractive error (anisometropic, ammetropic), obstruction (cataracts, blastoma, ptosis)

Question 4

squint types

Answer 4

tropia: at rest
phoria: latent; alternate cover test
horizontal conjugate gaze, one-and-a-half, internuclear ophthalmoplegia

version and duction
diplopia vs. fusional reserve

Question 5

normal vision

Answer 5

6/6
6/60 reduced

visual impairment:
3/60-6/60
6/24 with VF contraction
6/18 if severe VFD

severe VI: