IOP lowering does not affect visual function

Glaucoma treatment can, in certain metrics, improve quality of vision, according to a study published in the August 2008 issue of Eye.

T. S. Prata of the Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil and colleagues conducted a prospective, randomized trial to evaluate visual function prior to and after undergoing treatment for glaucoma. Subjects (n=54) were randomized to receive either timolol maleate, brimonidine tartrate or travoprost in one eye and were given Goldmann applanation tonometry (GAT), visual acuity, visual quality perception, standard automated perimetry (SAP) and contrast sensitivity (CS) tests before beginning and after conclusion of a four-week course of intraocular pressure (IOP) lowering treatment.

At baseline, subjects registered mean IOP levels of 7.8 mmHg; a SAP mean deviation index of 0.84 dB; visual quality perception of 0.56; and CS of 0.10 (12 cycles/degree) and 0.18 (18 cycles/degree). At the four week time point, these levels were 3.6 mmHg, 2.45 dB, 1.93, 0.37 (12 cycles/degree) and 0.42 (18 cycles/degree), respectively. In terms of visual function, however, no statistically significant changes were found. There were no differences noted between each of the treatment arms.

The team concluded that, regardless of medication used, IOP reduction is not correlated with an improvement in visual function, although visual quality perception, mean deviation and CS at higher frequencies all improve.