Comparison of retinal nerve fiber layer (RNFL) thickness and perimetry findings in glaucomatous patients

Aim: to determine the value of RNFL thickness at which visual field defect becomes detectable. Methods: Our study included 29 normal subject and 36 glaucomatous patient (one eye per person) .Every person was examined by OCTOPUS perimetry with glaucoma 30-2 program, and peripapillary RNFL thickness was measured by HIEDELBERGSPECTRALIS SD_OCT. Results: comparison of results showed higher sensitivity of OCT compared to Perimetry. Mean RNFL thickness at which visual field defect showed was 87 microns. Superior RNFL thickness value which correlated with inferior visual field defect was 101 microns, whereas inferior RNFL thickness value which correlated with superior visual field defect was 75 microns .and the difference in RNFL thickness between normal and glaucomatous visual field was significant (p<0.001). Conclusion: in open-angle glaucoma , it needs significant thinning in RNFL before visual field defects becomes detectable.