Colour vision and side-effects during treatment with methazolamide.
The retina contains Na+K(+)-ATPase and carbonic anhydrase (CA), enzymes that regulate ion fluxes across cell membranes of photoreceptors. Since inhibition of retinal Na+K(+)-ATPase by digitalis impairs colour vision, we wanted to find out whether this also occurs after inhibition of CA. In a double-masked cross-over study with placebo, 14 male volunteers were given 50 mg q.i.d. of the CA inhibitor methazolamide for 2 weeks. A disturbance of colour discrimination was observed in 8 of the 14 subjects, in the classification phase of Lanthony New Color Test. The presence of the disturbance was not significantly correlated to the degree of acidosis or to other side-effects. Its mechanism could be interpreted as a specific effect of CA inhibition in the retina (or the visual cortex) calculated to more than 99.9%.
Widengård
I
I
Department of Ophthalmology, University of Uppsala, Sweden.
Mandahl
A
A
Törnquist
P
P
Wistrand
P J
PJ
D000328:Adult; D002245:Carbon Dioxide / Q000097:blood; D003117:Color Vision Defects / Q000139:chemically induced*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008704:Methazolamide / Q000009:adverse effects* / Q000097:blood
D002245:Carbon Dioxide; D008704:Methazolamide