Packet 3 Ddx of Amblyopia

Question 1

Ddx of reduced visual acuity

Answer 1

• uncorrected refractive error
• amblyopia
• organic vision loss (ocular or neurological pathology, structural defect, nutritional, toxic)
• psychogenic/hysterical vision loss
• malingering

Question 2

3 types of organic vision loss

Answer 2

• pathology (ocular, neurological, structural)
• nutritional
• toxic

Question 3

characteristics of nutritional vision loss

Answer 3

-bilateral, symmetrical, painless VA loss
-central scotomas (80%), cecocentral scotomas
-aquired color R/G loss (50%)
-late phase has possible ONH pallor
-what happens: ganglion cell layer degeneration resulting in ON fiber layer atrophy
(often seen in severe alcoholics)

Question 4

characteristics of toxic vision loss

Answer 4

-sudden, bilateral, symmetrical VA loss
-central scotomas
-etiology: exposure to toxic agents (exogenous: lead, arsenic, methyl alcohol, cyanide, quinine) and (endogenous: focal infection)
lesion same as nutritional

Question 5

psychogenic/ non-organic vision loss is

Answer 5

alteration in sensory or voluntary motor functioning that suggests neurological or medical disorder characterized by substitution of physical signs/ symptoms for anxiety or emotional repression

Question 6

psychogenic/ non-organic vision loss causes what type of visual acuity characteristics

Answer 6

• decreased VA
• not consciously or intentionally produced
• cannot be fully explained by a medical condition

Question 7

prevalence and presentation of psychogenic/ non-organic vision loss

Answer 7

prevalence: 1.5-3.5%
presentation: blurred vision or no complaints, no prior vision problem or significant Rx, Hx includes possible psychogenic cause

Question 8

findings in psychogenic/ non-organic vision loss

Answer 8

• bilateral and typically equal decrease in VA (20/40-20/100)
• not related to refractive error, amblyopia, or other ocular disease
• constricted visual field (tubular, spiral)
• nonchalant
• sometimes can obtain 20/20 with little or no Rx

Question 9

characteristics of tubular visual fields

Answer 9

• bilateral, constricted, circular (usually 5-15 degrees of fixation)
• pathognomonic of hysteria (exception is malingering)
• no organic disease produces this VF
• apparently patients not conscious of it or it would limit mobility