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Editors Selection IGR 12-2

Therapeutic outcomes: Visual Field Improvement

Comment by Chris Johnson on:

57294 A Control Experiment for Studies that Show Improved Visual Sensitivity with Intraocular Pressure Lowering in Glaucoma, Anderson AJ; Stainer MJ, Ophthalmology, 2014; 121: 2028-2032

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Anderson and Stainer address a fundamental question in glaucoma - is the improvement in contrast sensitivity (perimetric increment threshold sensitivity) in glaucoma due to a general relationship between intraocular pressure (IOP) and visual sensitivity that is not directly related to glaucoma, or is the improvement in visual sensitivity for treated glaucoma (lowering of IOP) due to a reversible dysfunction that has been produced by high IOP? To address this question, the authors evaluated the IOP and visual field results from the Ocular Hypertension Treatment Study (OHTS). The OHTS data set is particularly valuable because it includes a large sample size (more than 1,300 patients) that was then followed for a long time interval with meticulous quality control and assessment procedures. Approximately half (692) of the participants in OHTS received treatment to lower IOP and about half (618) were watched carefully with no treatment administered. Additionally, the untreated group was offered treatment after five years of follow-up. Using a careful and thorough analysis of the relationship between IOP changes in the treated and untreated groups and visual field sensitivity for widespread (mean deviation or MD) and localized (pattern standard deviation or PSD) perimetric variation, the authors found that there was no significant difference in MD or PSD for the treated participants in comparison to the untreated participants. There was also no change in MD or PSD for the untreated patients who received treatment at a later date. These findings suggest that there is no relationship between IOP and visual field sensitivity that is unrelated to glaucoma and suggests that improvements in visual sensitivity in glaucoma after treatment is due to a reversal of a glaucoma-induced dysfunction of retinal ganglion cells produced by chronic elevated IOP.

Improvements in visual sensitivity in glaucoma after treatment is due to a reversal of a glaucoma-induced dysfunction of retinal ganglion cells produced by chronic elevated IOP.

This is a finding of high importance in terms of the current treatment regimens for glaucoma and the quality of life experienced by the patient. Also, it demonstrates the value of retrospective analysis of results from well-controlled multicenter clinical trials as well as the importance of framing meaningful and significant clinical management questions that additionally provide insights on the mechanisms underlying the glaucomatous disease process.

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