Inheritance: Autosomal recessive
Visual acuity 20/80–20/200
ERG: Normal rod response + absent cone response
Dark Adaptation: Loss of the cone plateau + loss of the cone–rod break.
Childhood nystagmus improves with increasing age.
A 7-year-old child is referred because of involuntary eye movements present since birth. Examination reveals obvious nystagmus, and best-corrected visual acuity is 20/160 in each eye. Color vision is also impaired. Which of the following descriptions is correct?
In Rod monochromatism:
(A) the rod response on ERG is normal while the cone response is abnormal. (B) On dark adaptation, the cone plateau and cone–rod break are absent. (C) the clinical findings are generally nonprogressive, and (D) specifically, the severity of nystagmus improves with age.