Retinal illuminance and the dissociation of letter and grating acuity in age-related macular degeneration.

PURPOSE: To report on the differential effect of retinal illuminance on letter and grating acuity. METHODS: For 13 subjects with age-related macular degeneration (ARMD) and four subjects with normal vision, standard distance and near letter acuity, as well as grating acuity data were obtained at mesopic to high-photopic light levels. RESULTS: In general, both acuity forms improved with increasing light level, but not in proportion with one another. The ratio of letter/grating acuity separated the ARMD subjects into two subgroups, one with relatively low letter acuity scores for which the dissociation of the two acuity forms increased with retinal illuminance, and another with higher letter acuity values for which the ratio converged toward unity. CONCLUSIONS: These findings demonstrate that both letter and grating acuity increase with retinal illuminance and that equating grating acuity with optotype acuity is untenable in subjects with ARMD, irrespective of light levels. The latter conclusion is of importance whenever acuity is used as a criterion to classify the visually impaired with regard to their legal and social status.

[Leukocoria (white pupil) among children--mother is always right]. / Leukokori (hvit pupill) hos barn--mor har alltid rett.

Leucocoria is a rare, but serious symptom in early childhood. It may be present at birth or develop during infancy. As in adults, infants usually display a black pupil, and upon shining a bright light into the pupil with the ophthalmoscope, an orange or red reflex emerges. The first person to see that something is wrong, is often the mother, but she cannot give a precise description. When the infant is crying it can be difficult to examine the red reflex, and the necessity of admitting the infant to an ophthalmologist, when the mother is worried, is discussed. In this paper we discuss two cases of retinoblastoma and one case of congenital cataract where the treatment was delayed due to late diagnosis of the leucocoria. The main conclusion is always to listen to the relatives when they are worried about the infant's eye, and to make sure that the infant is properly examined.