Relationship between severity of visual field loss at presentation and rate of visual field progression in glaucoma

Abstract

Purpose: To evaluate the relationship between severity of visual field (VF) loss at presentation and rate of VF progression in glaucoma.

Design: Clinic-based, retrospective study.

Participants: We included 512 eyes of 310 primary glaucoma patients.

Methods: We analyzed the VFs of all subjects of primary glaucoma who had >5 VFs between 1989 and 2008. Based on the mean deviation (MD), we classified the VF loss as mild (MD > -6 dB), moderate (MD ≤ -6 to ≥ -12 dB) or severe (MD < -12 dB). Guided Progression Analysis software which gives the rate of progression (ROP) of Visual Field Index per year was used to assess the ROP.

Main outcome measures: Relationship between severity of VF loss at presentation and ROP.

Results: The median duration of follow-up was 6.8 years. The ROP increased (worsened) by 0.02% per year for every dB worsening of MD (P = 0.02) and for every year of increasing age (P = 0.001). Association between MD and ROP showed a significant positive relationship in mild (β = 0.18; P = 0.001) and a significant negative relationship in severe (β = -0.16; P<0.001) VF loss category. Association between MD and ROP was not significant in the moderate VF loss category (β = -0.05; P = 0.61).

Conclusions: In early stages of glaucoma, the ROP worsened as the severity increased, but, in later stages of the disease, ROP became smaller as the severity increased. There is a need for better methods to detect progression in eyes with severe glaucomatous damage.