Abstract
Purpose :
To investigate the incidence and risk factors for glaucomatous visual field progression in eyes with apparently well-controlled intraocular pressure (IOP).
Methods :
This was an observational longitudinal study. We investigated visual field changes during a 5-year follow-up period of a group of 462 eyes of 335 patients with glaucoma followed under treatment. 196 of the 462 eyes (42%) had seemingly well-controlled IOP, defined as IOP no higher than 18mmHg at all visits during follow-up. For eyes with history of laser or surgical IOP-lowering treatment, only the period anteceding the procedure was considered. Rates of visual field progression were evaluated by ordinary least-squares linear regression of standard automated perimetry (SAP) mean deviation (MD) values over time. Progression was defined as statistically significant negative rate of MD change over time (alpha=0.05). Corneal hysteresis measurements were obtained by the Ocular Response Analyzer (ORA, Reichert, Inc.) yearly during follow-up.
Results :
47 (24%) of the 196 eyes with seemingly well-controlled IOP had progressive visual field loss, while 149 (77%) remained stable over time. Mean rate of MD change was -1.0 ± 0.7dB/year versus 0.1 ± 0.5dB/year (P<0.001) for the two groups, respectively. There was no significant difference in baseline MD (-6.5 ± 6.8 vs -6.5 ± 6.4 dB; P=0.96, respectively) between the two groups. There was also no statistically significant difference in mean IOP (11.6 ± 2.1 vs. 12.0 ± 2.4 mmHg; P=0.30), IOP fluctuation (1.71 ± 0.59 vs. 1.66 ± 0.56 mmHg; P=0.55) or peak IOP (14.3 ± 1.9 vs. 14.5 ± 2.2mmHg; P=0.68) during follow-up in progressing versus stable eyes, respectively. Eyes with seemingly well-controlled IOP that showed visual field progression had significantly lower mean corneal hysteresis values compared to those that remained stable (8.7 ± 1.3 vs. 9.4 ± 1.6 mmHg; P=0.004), as well as thinner central corneal thickness (518 ± 35 vs. 532 ± 42 mm; P=0.048).
Conclusions :
Up to one-quarter of eyes with apparently well-controlled IOP may show visual field progression over time. Thin cornea and low corneal hysteresis are risk factors for progression in these eyes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.