Table 8.

Groups 1–3 mild to severe based on electrophysiology findings, described by Lois et al. ²⁴⁶

Lois group	Electrophysiology findings
Group 1	Abnormal PERG with normal ffERG
Group 2	Cone dysfunction
Group 3	Cone and rod dysfunction

ffERG, full field electroretinogram; PERG, pattern electroretinogram.