Abstract
Purpose: :
To determine the combination of functional and structural tests that will identify progression of glaucomatous damage.
Methods: :
Ninety eyes of 46 subjects with open-angle glaucoma and corrected visual acuity of >=20/40 were enrolled in a prospective study. Testing procedure involved two baseline and follow-up examinations at 6-month intervals. At each visit the following tests were performed: frequency doubling perimetry (FDT) with the Humphrey Matrix (24-2 program, ZEST), standard automated perimetry (SAP) with the Humphrey Field Analyzer II (24-2 program, SITA), multifocal visual evoked potentials (mfVEPs) with the VERIS system using a 60 sector pattern-reversal dartboard array, pattern electroretinography (PERG) with Glaid and measurements of optic nerve head topography with the OCT III. To identify progression, the two baseline measurements for the following were averaged: mean deviation (MD) and pattern standard deviation (PSD) for FDT and SAP, response amplitudes for PERGs, number of abnormal test locations with probability values of 1% and 5% for the mfVEP, and average retinal nerve fiber layer (RNFL) thickness for the OCT. These averaged values were compared to those obtained at the most recent examination.
Results: :
Twenty-nine eyes have been followed for a median of 21 months. For SAP, comparisons to the averaged baseline MD and PSD values showed significant changes suggesting progression in 4 (14%) eyes for MD, but in only 2 (7%) eyes for PSD. For FDP there were significant changes in MD in 11 (38%) eyes, but in only 3 (10%) eyes for PSD. Four eyes (14%) showed changes in MD for both visual field methods. The number of abnormal test locations for the mfVEP was increased in 4 (14%) eyes suggesting progression. However, 3 of these eyes did not show significant changes in either SAP, or FDT, MD and PSD values. PERG response amplitudes were decreased in 4 (14%) eyes, none of these eyes showed significant changes for the visual field tests. OCT RNFL average thickness values were decreased for 9 (31%) eyes.
Conclusions: :
All the tests showed evidence of progression of glaucomatous damage. Except for the MD for FDT, the percentage of eyes showing changes on functional tests was very similar. However the agreement, regarding which eyes showed progression, was poor. In addition more eyes were identified as showing progression with the structural test. These discrepancies illustrate the importance of following patients with a combination of functional and structural tests.
Keywords: visual fields • electrophysiology: clinical • imaging/image analysis: clinical