Table 1

Clinical characteristics of X chromosomal cone-rod dystrophies and CSNB2

	CORDX3	CSNB2	X chromosomal cone-rod dystrophy(CORDX1, CORDX2)
ERG, electroretinogram; D, diopter; VA, visual acuity; VF, visual field.
	Mäntyjärvi et al⁶	Pearce et al¹⁶	Pinckers and Timmerman³
		Tremblay et al¹⁸	Jacobson et al²
		Bech-Hansen et al²³	Kellner and Foerster⁵⁰
		Boycott et al¹⁵	Meire et al⁴
		Nakamura et al⁴¹	Hong et al⁵
		Langrova et al⁴⁹	Bergen and Pinckers¹²
		Allen et al¹⁹	Brown et al¹
		Jacobi et al⁴⁰
1. Onset	As child, adult	Congenital	As child, adult
2. Progression	VA, refraction, VF, colour defect	Stationary	VA, refraction, VF, colour defect
3. VA (range)	20/300–20/40	20/400–20/25	20/800–20/15
4. Refraction (range)	−1 to −24 D	+8 to −18.25 D, mostly myopia	+3.25 to −20 D, mostly myopia
5. Astigmatism >1.5 D (eyes)	0/20	137/266, up to 5.5 D	9/32, up to 3 D
6. Congenital nystagmus (patients)	0/10	67/139	Rare
7. Ocular fundus	Normal,	Normal,	Normal,
	myopic changes	hypopigmentation, no foveal reflex,	macular atrophy, “bull’s eye“,
		tilted disc, pale disc,	hypopigmentation,
		myopic changes	myopic changes
8. Colour vision	Normal, protan	Normal, tritan, non-specific defect	Tritan, deutan, protan, achromatopsia
9. VF	Normal, central scotoma,	Normal,	Normal, central scotoma,
	central reduced sensitivity,	central scotoma	paracentral scotoma,
	concentric constriction		reduced central, paracentral sensitivity
10. Dark adaptation	Cone threshold missing or elevated,	Cone threshold elevated,	Cone threshold missing or elevated,
	rod threshold normal or elevated	rod threshold elevated	rod threshold normal or elevated
	<1 log unit	0.5–3 log units	1 log unit
11. ERG	Negative ERG,	Negative ERG,	Scotopic a and b wave decreased,
	30 Hz flicker decreased	30 Hz flicker abnormal/decreased	photopic b wave decreased,
		with double-peaked wave	30 Hz flicker decreased,
			negative ERG possible