Methodology of glaucoma varies widely in published studies

Large disparities in study design, diagnostic parameters and success criteria were found in a review of published studies of glaucoma, revealing “the complexity of the disease,” according to a group of researchers.

Oliver Schwenn, MD, and colleagues analyzed 101 studies published between 1996 and 1999 in 11 well-read peer-reviewed periodicals to assess the studies’ methodologies.

They found wide variations in criteria, including 95 different definitions of success in the 63 studies that explicitly defined success.

Their analysis showed that in more than half of the studies, the study follow-up duration was 1 year or less, and only in 5% did follow-up exceed 4 years.

Of the 101 studies, 41 included less than 50 patients, while 34 included more than 100 and 11 included more than 250 patients.

“Examples of prestigious studies show the necessity of observation periods of several years and demonstrate the need for a high number of participants,” the study authors said.

Four studies gave what the authors called “insufficient data.”

All 101 studies measured IOP, but only 45 studies described the method of tonometry, and only 13 measured diurnal IOP. This led the authors to suggest that clinical studies should specify the measurement method clearly.

“The lack of a common definition of success reveals the complexity of the disease,” the authors said. “However, an IOP reduction based on the degree of damage and ascertaining the target pressure seems sensible.”

The study is published in the July issue of Graefe’s Archive for Clinical and Experimental Ophthalmology.