Achromatopsia

Reduced vision due to lack of functioning cones
- Vision usually 20/200 with complete color blindness in complete forms
- Incomplete forms may have better vision and some color vision
Nystagmus that may improve with age
Central relative scotoma with normal peripheral visual fields
Complete and Incomplete forms
Usually stable but some see slow worsening of visual acuity and macular atrophy

Photophobia at birth or early infancy
Better vision in dim illumination
Sluggish pupil responses with paradoxical constriction in the dark
Usually normal fundus appearance
- OCT may show ellipsoid zone disruption or absence, outer retinal atrophy and RPE loss
ERG
- lack of cone function- 30 Hz flicker and single flash photoptic waveform is small and delayed
- normal ROD function- normal dark adapted dim and bright flash waveforms

1 in 30,000 live births
Recessively inherited mutation in a gene that codes for a part of the cone phototransduction pathway.
70-80% from mutations in the following genes: CNGA3 and CNGB3
1-2% from mutations in GNAT2, PDE6C, PDE6H, ATF6