Comparative evaluation of optical coherence tomography in glaucomatous, ocular hypertensive and normal eyes

Background: To correlate the findings of optical coherence tomography (OCT) evaluation of retinal nerve fiber layer (RNFL) thickness with visual field changes in glaucomatous, ocular hypertensive and normal eyes. Materials and Methods: Thirty consecutive normal, 30 consecutive ocular hypertensive and 30 consecutive glaucomatous eyes underwent a complete ophthalmic examination, including applanation tonometry, disc evaluation, (30-2) Humphrey field analyzer white on white (W/W) perimetry and short- wavelength automated perimetry. Thickness of the RNFL around the optic disc was determined with 3.4 mm diameter-wide OCT scans. Average and segmental RNFL thickness values were compared among all groups. A correlation was sought between global indices of perimetry and RNFL thickness. Results: Of the 90 eyes enrolled (mean age of patients 52.32±10.11 years), the mean RNFL thickness was significantly less in ocular hypertensive (82.87±17.21 mm; P =0.008 and glaucomatous eyes (52.95±31.10 mm; P < 0.001), than in normals (94.26±12.36 mm). The RNFL was significantly thinner inferiorly in glaucomatous eyes (64.41±43.68 mm; P < 0.001) than in normals (120.15±14.32 mm) and ocular hypertensives (107.87±25.79 mm; P < 0.001). Ocular hypertensives had thinner RNFL in the nasal, inferior and temporal quadrants ( P < 0.001) when compared to normals. Global indices in ocular hypertensives on SWAP showed Mean Deviation (MD) of 5.32±4.49, Pattern Standard Deviation (PSD) 3.83±1.59 and Corrected Pattern Standard Deviation (CPSD) 2.84±1.85. The RNFL thickness could not be significantly correlated with global indices of visual fields in ocular hypertensives. Conclusion: Optical coherence tomography is capable of detecting changes at the level of RNFL in ocular hypertensive eyes with normal appearance of discs and W/W perimetry fields