Abstract
Purpose: :
To determine if the visual field progression in glaucoma is dependent on the severity of the visual field loss at presentation.
Methods: :
Of the 1583 subjects, who had more than 5 Humphrey Visual Field examinations between 1989 and 2008, those with a diagnosis of primary glaucoma and were treated by a single physician were selected. The visual fields of these subjects were analysed by the Guided Progression Analysis (GPA) which gives the Visual Field Index (VFI) and the regression slope of VFI per year as Rate of Progression (ROP). Hodapp-Anderson-Parrish classification was used to categorize visual field loss into mild, moderate and severe based on the Mean Deviation (MD) at presentation. Based on the ROP, visual field was considered either as progression (p<1%), borderline progression (p<5%) or stable (not significant or p>5%). Relationship between MD and ROP was assessed by 3 methods.
1. Linear regression of ROP against MD
2. Comparison of ROP in mild, moderate and severe field loss at presentation
3. Comparison of MD at presentation in the eyes with progression, borderline progression and stable visual fields
Results: :
Five hundred and thirty eyes of 311 subjects were analysed (227 men, 84 women). Mean age (± SD) was 63.23 ± 13.09 years. Mean duration of follow-up was 84.78 ± 37.33 months. Mean number of fields were 7.06 ± 2.16. Mean MD, PSD and VFI at presentation were -9.93dB ± 8.62, 5.71dB ± 4.02 and 76.52 ± 27.51 respectively. ROP for the entire cohort was -0.81 ± 2.18.
1. Regression co-efficient for ROP against MD was 0.007 (p=0.874)
2. The mean ROP values of eyes with mild (-0.65 ± 1.53, n=247 eyes), moderate (-0.84 ± 2.48, n=102 eyes) and severe (-1.02 ± 2.68, n=181 eyes) field loss at presentation were not significantly different (p=0.22)
3. The mean MD values of the eyes with progression (-9.72dB ± 7.45, n=57 eyes), borderline progression (-10.71dB ± 8.36, n=71 eyes) and stable visual fields (-9.83dB ± 8.84, n=402 eyes) were also not significantly different (p=0.716).
Conclusions: :
In this cohort, visual field progression in glaucoma is independent of the severity of visual field loss at presentation.