Structure-Function Correlations of Glaucoma in Filipinos

Abstract

Introduction: To determine the structure-function correlations of glaucoma in Filipinos using the average peripapillary retinal nerve fiber layer (RNFL) thickness and rim area (RA) of the spectral-domain optical coherence tomography (SD-OCT) and mean defect (MD), pattern standard deviation (PSD), and visual field (VF) clusters of standard automated perimetry (SAP).

Methods: Consecutive tests consisting of SD-OCT, SAP, and disc photos were reviewed and selected based on abnormalities in VFs or OCTs or both. Each set of tests was classified as to VF defect type and severity. Mean threshold of VF clusters, MD, and PSD were correlated with average and sectoral RNFL thicknesses and RA.

Results: One hundred eighty-six (168) eyes of 121 patients with mean age of 60.2 ± 14.7 years had an average MD, PSD, RNFL thickness, RA of -9.5 ± 8.5 dB, 5.4 ± 3.3 dB, 75.9 ± 15.9 μm, and 0.9 ± 0.4 mm2, respectively. Among VF tests, 23.1% were normal, 16.5% had early, 9.1% moderate, 12.4% advanced, and 8.3% severe glaucoma damage. Most common VF defect types were central islands, combined, and paracentral (16.5%, 14.4%, and 12.2%, respectively). The most commonly affected RNFL segments were inferior, followed by superior, and combined superior and inferior (51.2%, 47.1, and 34%, respectively). Among the OCT parameters, RNFL thickness and RA were strongly correlated (p<0.0001). Between the VF and OCT parameters, the strongest correlation was between the clusters of superior VF defects and the 6-8 o’clock RNFL thinning, followed by the inferior VF defects and the 12-1 o’clock RNFL thinning. Inferior RNFL thinning was strongly correlated with MD and PSD.

Conclusion: Among Filipino glaucomatous eyes monitored with SD-OCT and SAP, correlation was strongest between the superior VF defects and the infero-temporal RNFL thinning.