Visual Field and Structural Correlates of Progression in Age-Related Macular Degeneration

Abstract

Purpose: : To examine the correlation of central visual field loss and progression of structural changes in the macular area in age-related macular degeneration (AMD).

Methods: : Central 10° standard and short-wavelength automated perimetry (SWAP) visual fields were acquired in 39 eyes of 24 patients with AMD using a Humphrey Field Analyzer. Stereoscopic fundus photographs were graded¹ by two independent observers and the stage of disease determined². Custom software mapped perimetric data onto fundus images in order to relate structural changes to functional loss.

Results: : Mean deviation (MD) in standard perimetry changed from 0.04 dB at stage 1 to -12.39 dB at stage 4 (r²=0.48, p<0.001). The group mean SWAP MD was -5.26 dB at stage 1 and increased to -17.08 dB at stage 4 (r²=0.53, p<0.001). Pattern standard deviation (PSD) also increased with advancing stage in standard perimetry; 1.32 dB to 8.67 dB at stage 1 and 4, respectively (r²=0.54, p<0.001). In SWAP, PSD increased from 2.86 dB to 5.63 dB at stage 1 and stage 4 (r²=0.43, p<0.001). Defect frequency was greater in SWAP than standard perimetry. Early stage defects occurred with the greatest frequency at eccentricities of 3.2° and 5.1° in standard perimetry and at 4.2° in SWAP. Late stage defects were most frequent at 1° eccentricity in standard perimetry and at 1° and 9° in SWAP. MD declined with increasing affected retinal area over the central 3000µm; by 0.20 dB (r²=0.67, p<0.001) and 0.18 dB (r²=0.49, p<0.001) per % increase in defect area for standard perimetry and SWAP respectively. 41% of defects were associated with structural changes on the retina in standard perimetry and 43% in SWAP.

Conclusions: : Sensitivity decreased with advancing stage of AMD, with a greater effect demonstrated in SWAP compared to standard perimetry. The central field became less uniform as stage increased. SWAP defects occurred at similar locations but were deeper and wider than corresponding defects in standard perimetry. Central loss in SWAP is a sensitive marker of functional progression in AMD.1. Bird et al. (1995) Surv Ophthalmol 39:367-3742. van Leeuwen et al. (2003) Arch Ophthalmol 121:519-526

Keywords: age-related macular degeneration • visual fields • perimetry