Alex E. Krill

Galactokinase Deficiency as a Cause of Cataracts

Abstract Galactokinase and galactose-1-phosphate uridyl transferase assays were carried out on blood samples from 210 persons in whom cataracts developed before the age of 40. In two patients, both...

Similarities between Congenital Tritan Defects and Dominant Optic-Nerve Atrophy: Coincidence or Identity?*

Dominant inherited optic atrophy is usually a stationary disorder with typical findings of optic-nerve pallor, abnormal distance acuity but essentially normal reading vision, minimal visual-field defect, and characteristic color confusions in the blue–green region of the spectrum. The severity of these is extremely variable, even within the same family. In patients with minimal disease, distance acuity may be close to normal and optic pallor may be so subtle that a definitive diagnosis cannot be made unless several affected members of a family are seen. An evaluation of ocular- and color-vision findings are presented for three pedigrees. Color tests included determination of the Rayleigh equation, the American Optical HRR plates, the Farnsworth–Munsell 100-hue test, and determination of netural points and chromaticity confusions. Our results suggest a strong similarity in color vision between previously reported congenital tritan defects and patients with dominantly inherited optic atrophy. Criteria distinguishing the two conditions are suggested. However, a perusal of the literature reveals that most congenital tritanopes were not adequately evaluated to rule out dominantly inherited optic atrophy. Therefore, the almost identical color-vision profiles and pattern of inheritance of the two conditions lead us to question the existence of congenital tritan defect as an independent entity.

Red-Light Thresholds in Heterozygote Carriers of Protanopia: Genetic Implications

Absolute thresholds in response to red light were compared in nine normal subjects, six female carriers of protanopia (heterozygotes), and six male subjects with protanopia. The fovea and four peripheral retinal areas were tested, and all data were obtained before the occurrence of the rod-cone break. Elevated thresholds were found in all retinal areas tested in protanopic males, at the fovea in all carriers, and in some peripheral retinal areas in two carriers. The thresholds for carriers were far below those for the protanopic males, and no greater variability of threshold was found in the carriers when they were compared with the normal control group. The findings do not substantiate the occurrence of inactivation at the locus on the X chromosome for protanopia.

TOTAL COLOR BLINDNESS AND ALBINISM. TWO CAUSES OF SUBNORMAL VISUAL ACUITY IN CHILDREN.

Color blindness and albinism in children are frequently unrecognized. Color blindness may be either incomplete or total, and albinism may be universal, incomplete universal, or ocular in type. The most common symptoms in both disorders, aside from the reduced visual acuity, are photophobia and nystagmus. The pale appearance of the iris and fundus in albinism and the abnormal response to color vision tests in color blindness are important aids to diagnosis. The need for an exact diagnosis is stressed.