Comparing Definitions of Glaucoma Progression in the Glaucoma Longitudinal Imaging Study (GILS)

Abstract

 

Purpose:

 

To determine which eyes in the Glaucoma Imaging Longitudinal Study (GILS) demonstrated progressive damage.

 

Methods:

 

The GILS followed a cohort of established glaucoma patients with definite visual field (VF) and optic disc damage every 6 months using Humphrey 24-2 SITA Fast VF and the Heidelberg Retina Tomograph 2 (HRT2). Eyes with a minimum of ≥5 high quality Humphrey 24-2 SITA fast visual fields amenable to GPA analysis and ≥ 4 Heidelberg Retina Tomograph 2 (HRT 2) studies were evaluated for glaucomatous progression, defined as Glaucoma Progression Analysis (GPA) classification of "possible" or "likely", or significant sector rim thinning determined by HRT2.

 

Results:

 

115 eyes of 84 subjects (from 312 eyes of 205 subjects in the GILS) met the inclusion criteria. The mean ± standard deviation follow up was 39 ± 7 (range 22 to 52) months. Thirty-two eyes of 28 subjects progressed, 21 by HRT 2 criteria (mean time to progression 16.3 ± 11.9 months), and 19 by GPA visual field criteria (7 "likely" and 12 "possible", mean time to progression 29.3 ± 5.3 and 31.0 ± 7.9 months, respectively). Five eyes were classified as "improved" by HRT 2 criteria (GPA does not have an "improved" classification).

 

Conclusions:

 

In this cohort of eyes with established glaucomatous visual field loss at the outset, approximately equal number of eyes progressed by either disc or field criteria, but few eyes progressed by both. With the specific criteria for progression that we chose, progression was detected earlier in general by HRT2. Depending upon the criteria chosen, the crude progression rate in this cohort ranges from approximately 1% (HRT2 plus GPA likely) to 9% annually (either HRT2 or GPA or both).  

 

Keywords: imaging/image analysis: clinical • perimetry • clinical (human) or epidemiologic studies: outcomes/complications