Abstract
Purpose :
To estimate the proportion of patients in glaucoma clinics in the US progressing to significant visual impairment within their expected lifetime, we investigated the rates of visual field (VF) change based upon global (mean deviation, MD) and central (macular total deviation, mTD) metrics.
Methods :
This retrospective study included VF data from 6 referral glaucoma practices in the US (GRN database: ~1 million VF tests of ~190,000 patients). Patients were ≥35 years, with ≥5 24-2 VFs (false positive rates ≤30%; fixation losses <20%), ≥3 years of follow-up, and abnormal baseline VFs (MD or PSD at P<5%).1 Linear mixed effects models were used to calculate the rates of VF change based upon global (MD) and macular (average TD of the 4 central-most locations, mTD) metrics. Estimated life expectancy from the time of the last VF test was derived from US Census data. We employed 3 criteria to define significant visual impairment: (A) MD ≤-22 dB1, (B) mTD ≤-15 dB,2 and (C) mTD ≤-22 dB.
Results :
14,828 eyes of 7,722 patients were analyzed. Mean±SD age at baseline was 66.1±11.3 years and baseline MD and mTD were -7.2±7.3 and -6.0±7.4 dB, respectively. Patients underwent 9.1±5.5 VF tests spanning 6.8±2.5 years. The mean rates of MD and mTD change were -0.30 dB/year (95% CI: -0.31 to -0.28, P<0.001) (Fig. 1) and -0.30 dB/year (95% CI: -0.32 to -0.29, P<0.001) (Fig. 2), respectively. However, 247 (1.6%) and 467 (3.1%) of eyes progressed at MD and mTD slopes ≤-1.5 dB/year (P<0.001). At baseline, the number of patients with at least one visually impaired eye based upon criteria A, B, and C were 861 (11.5%), 1,729 (22.3%), and 711 (9.2%). At the end of the predicted lifetime, these numbers were 2,296 (29.7%), 3,384 (43.8%), and 2,270
(29.4%).
Conclusions :
Upon baseline 24-2 VF assessment, a substantial proportion of patients seen in referral glaucoma practices in the US suffer from significant visual impairment in at least one eye. This proportion tripled in their predicted lifetime and was more pronounced in the central field, despite the limitations of 24-2 strategy to detect macular damage. These findings support the importance of monitoring macular damage in glaucoma.3
References:
1-Saunders et al. Invest Ophthalmol Vis Sci. 2014;55(1):102-9.
2-Mills et al. Am J Ophthalmol. 2006;141(1):24-30.
3-Hood et al. Prog Retin Eye Res. 2013;32:1-21.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.