One–year changes in visual field, HRT, and RTA parameters in the Glaucoma Imaging Longitudinal Study (GILS)

Abstract

Abstract: : Purpose: Assessing progression is a critical challenge in glaucoma research and clinical practice. The Glaucoma Imaging Longitudinal Study (GILS) is a longitudinal study of glaucoma patients designed to determine whether decreases in macular thickness and/or optic disc and nerve fiber layer changes precede visual field changes. We examined whether structural or functional changes could be detected with one year follow–up. Methods: Participants in the GILS undergo semi–annual examinations including SITA fast visual field testing (VF), Heidelberg Retinal Tomograph (HRT II) imaging of the optic disc, stereo fundus photography, and scanning with the Retinal Thickness Analyzer (RTA). We compared the visual field results, HRT images, and RTA images at baseline and at twelve months in the subset of subjects with good quality HRT (TSD < 50) and RTA images (>75% of points represented) at both baseline and 12 month visits. We defined changes as follows: for VF, mean deviation (MD) change of 3 dB or pattern standard deviation (PSD) change of 2 dB; for HRT cup shape measure (CSM) change of 0.02 or rim area (RA) change of 0.2 mm2; for RTA, change in macular thickness either inferiorly (RTA inf) or superiorly (RTA sup) of ≥13 um. Results:37 eyes of 28 subjects met the inclusion criteria. % eyes with change over first year 

More eyes had an improved cup shape measure than had a worsened cup shape measure at the one year follow–up (p=0.004). The results were the same when individual sectors were analyzed and when the 6 eyes with TSD > 30 were not included in the analysis. Conclusions: Cup–shape measure was the only parameter that did not demonstrate an even distribution of improvement or worsening at one year. The change (more negative cup shape measure) we observed is opposite to what we expected (worsening of cup shape measure with time) in a cohort of glaucoma patients. Ongoing follow–up will allow us to assess the prognostic significance of disc and macular changes in monitoring glaucoma progression.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea • optic disc