Abstract
Purpose::
To determine the spatial characteristics of glaucomatous visual field progression in persons with glaucomatous appearing optic neuropathy (GON) from the Diagnostic Innovations in Glaucoma Study (DIGS).
Methods::
Changes in pattern deviation (PD) plot values from the average of two baseline exams to two follow-up exams were evaluated in test locations. All exams were eligible, full threshold, pattern 24-2, standard automated perimetry (SAP) exams (Humphrey Field Analyzer II) in visual field series from 200 patients with GON confirmed on two occasions by masked stereophoto review. The proportion of patients exhibiting PD plot progression was determined at each of 52 locations for patients with a baseline abnormal p-value (p < 5% or worse) in one or more of 52 PD locations in either the first or second baseline test for a total of 2704 location pairings for each possible level of negative PD change from -1 dB to -50 dB. Progression was defined as any worsening of PD plot value in the follow-up test relative to the average PD plot value in the baseline tests. Monte Carlo simulation was employed to determine the significance of the observed patterns of PD plot progression.
Results::
Changes in PD values were dependent on their location relative to abnormal PD locations in the first test. Of those patients with an abnormality at a location at baseline (mean = 0.23 ± 0.07), the proportion of patients changing by -2 dB or more ranged between 0.09 and 0.55 (mean = 0.29 ± 0.06) across locations. For changes of -6 dB or more, the proportions ranged between 0.00 and 0.26 (mean = 0.08 ± 0.04) of patients. These proportions and the proportional p-values for each of 2704 location pairings are reported for selected levels of change. The proportional p-values are consistent with a map of the retinal nerve fiber layer bundles (Wilcoxon Rank Sum, p < 0.0001).
Conclusions::
Visual field progression occurs in retinotopically constrained patterns consistent with changes along the nerve fiber bundle.
Keywords: visual fields • perimetry