Rate of Visual Field Decay in Glaucomatous Eyes with Acquired Pits of the Optic Nerve

Abstract

Purpose : Acquired pits of the optic nerve (APON) in glaucoma have been associated with visual field (VF) defects and progressive optic disc damage. Characterizing the rate and mode of VF decay in patients with APON could further guide clinical decision-making. The aim of this study is to evaluate the association between APON and rate of local and global VF decay in primary open-angle glaucoma (POAG) patients.

Methods : POAG patients of the UCLA Stein Eye Institute Glaucoma Division from 1996 to 2016 were screened for APON by qualitative assessment of optic disc stereoscopic photographs by three independent, masked experts. A control group of POAG eyes without APON were matched for age, gender, baseline IOP, VF mean deviation (MD), and follow-up duration. Proportions of decaying, improving, or stable serial test locations and their pointwise rates of change (% of perimetric range/year) were calculated with exponential regression. Indices of VF rate of change were calculated with MD rate, visual field index (VFI) rate, and the Glaucoma Rate Index (GRI) - a normalized sum of pointwise rates of change.

Results : Twenty-six eyes of 22 POAG patients with APON were identified. The number of decaying locations did not differ significantly between the two groups (p = 0.10); however, mean rate of change of all test locations was significantly faster in the APON group (-0.83 ± 3.29 %/yr vs. -0.40 ± 2.40 %/yr; p = 0.004). The MD rate (mean ± SD) was significantly faster in the APON group (-0.23 ± 0.26 dB/yr vs. -0.06 ± 0.54 dB/yr, p = 0.024), while VFI rate was not significantly different (p = 0.14). As measured with GRI, eyes with APON had twice the decay index as did the non-APON eyes (p = 0.043).

Conclusions : The presence of APON in POAG is associated with a more rapid rate of VF decay than those of POAG eyes without APON. Glaucomatous eyes with APON suggest a phenotype of focal optic nerve vulnerability with fast progression; identification of such patients can alert clinicians to the likelihood of fast functional deterioration.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Frequency distribution of pointwise rates of change (% perimetric range/yr) of all serial test locations in APON (blue bar) and non-APON (red bar) eyes

 

Spatial distributions of mean VF pointwise rate of change for control (left) and APON (right) eyes. Grey scale indicates rates in % perimetric range/yr; negative values indicate decay and positive improvement