Congenital Stationary Night Blindness (CSNB) is, as its name suggests, a nonprogressive (stationary) disorder.

It is associated with myopia, and its most common inheritance pattern is X-linked.

Clinical examination:

• Normal posterior segment appearance
• ± Paradoxical pupillary response to darkness: initial miosis, followed by mydriasis

ERG: Electronegative ERG

Dark Adaptation: Reduced response

Differential diagnoses of a negative ERG:

1. Drugs causing RGC toxicity, such as methanol and quinine
2. Siderosis
3. CSNB
4. Birdshot chorioretinopathy
5. Melanoma-associated retinopathy (MAR)
6. X-linked retinoschisis (XLRS)
7. CRAO
8. Duchenne dystrophy

In Duchenne dystrophy, an electronegative ERG may be present in the absence of pigmentary retinopathy.

A 33-year-old man presents with a history of night vision difficulty since childhood. Best-corrected visual acuity is 20/30 in both eyes. Fundus examination reveals no pathological findings. Electrophysiologic testing demonstrates a negative ERG pattern. Which of the following statements is incorrect?