• Written By: Jefferey Freedman, MD

    This prospective study found that topical glucose can temporarily improve contrast sensitivity in some open-angle glaucoma patients, suggesting that neuronal energy substrate may help recover function of “sick” retinal neurons.

    The authors theorize that glaucoma is associated with energy insufficiency at the optic nerve head resulting in damage to optic nerve fibers and thereby a decrease in visual potential. They have previously shown in an experimental model that a glucose infusion has a neuroprotective effect against acute retinal ischemia, prolonged ischemic retinal injury, and glaucomatous optic nerve neurodegeneration.

    This study represents a “first-in-human” attempt to translate their retinal bioenergetics research from the laboratory to the clinic. It was a double-blind, randomized, crossover study that included four phakic and four pseudophakic patients who received 50% glucose followed by 0.9% saline or vice versa, every five minutes for one hour, with a “washout period” of two to three weeks. A follow-up study included four patients from the original study and another three suitable patients. The protocol for this study was identical to the first one except that patients received 8% saline (osmolarity matched to 50% glucose).

    The 50% glucose reached the vitreous in pseudophakic but not phakic individuals. In the follow-up study, glucose significantly improved the mean contrast sensitivity at 12 cycles/degree compared with 0.9% saline (by 0.26 log units in study one and 0.40 log units in the follow-up study). The glucose drops did not affect IOP, refraction or central corneal thickness.

    The problem with topical application of glucose is the rather rapid rate of decline in concentration in the vitreous. Nonetheless, the beneficial effects of topical glucose warrants further study.