The patients were cognitively normal without a history of developmental delay, seizures, or cerebral palsy and without a focal abnormality on neurologic examination outside of the visual system. No patient had a developmental abnormality of the anterior or posterior globe.
Table 2details neuro-ophthalmic examinations. Visual acuity (VA) ranged from 20/30 to CF at 3′ with a mean of 20/200. The VAs in an individual’s two eyes correlated strongly (
r = 0.931;
P < 0.0001). Mean CV was less than 3 of 10 pseudoisochromatic plates, and color vision correlated strongly with VA (
r = 0.51;
P = 0.003). Most patients had flat, pale optic disks typical of optic atrophy (OA) that were roughly symmetric in appearance in the two eyes
(Fig. 1A) . Some fundi had an appearance reminiscent of dominant OA
(Fig. 1B) , but four (patients 3, 4, 11, and 15) had small optic disks
(Fig. 1C)more typical of ONH. Optic disc diameter did not correlate with VA, color vision, or ocular motility. Dilated funduscopic examination revealed no obvious pigmentary retinopathy, macular disruption, or other retinal abnormality that might explain poor vision. No patient had congenital cataracts, elevated IOP in either eye, or an optic disc appearance or visual field loss more typical of glaucoma. No patient who could perform confrontation or formal VFs had a major arcuate or altitudinal VF defect. Some patients with moderately reduced VA in both eyes had no central scotoma documented on Goldmann VF. Goldman VF and tangent screen testing sometimes fail to detect central VF loss in metabolic optic neuropathies,
26 27 28 and this medically unsophisticated population, some of whom had congenital nystagmus, also had relatively poor fixation. All patients had full ocular motility, although nine had some degree of strabismus (four with esodeviation and five with exodeviation), one had dissociated vertical deviation in both eyes, and nine had congenital nystagmus of varying amplitude. The presence of congenital nystagmus was modestly correlated with color vision (
r = 0.445;
P = 0.011), but this result is best considered informative rather than definitive given the number of statistical tests performed. Congenital nystagmus was not correlated with VA, optic disc diameter, or strabismus.