To the Editor.
—I found especially interesting Flynn and Brod's1 letter in the Archives on protection from operating microscope-induced retinal phototoxicity during pars plana vitrectomy.Retinal phototoxicity is of special importance in patients with glaucoma. It matters relatively little, and probably not at all from a functional point of view, when an individual with a normal complement of retinal receptors and appropriate connections to the geniculate body has a small percentage of neuronal elements temporarily or even permanently damaged. However, in the patients with far-advanced glaucoma, who may have only a tiny percent of their neurons remaining, often concentrated in the macular area, damage or death of five to ten thousand neurons may represent a devastating loss.My colleagues and I have had one patient with far-advanced glaucoma experience a diminution of visual acuity from 6/9 to 6/15, following photography of his optic discs. Some of the loss of