Correlation of axial length and peripapillary retinal nerve fiber layer thickness measured by Cirrus HD optical coherence tomography in myopes

Purpose: To evaluate the RNFL thickness by optical coherence tomography (OCT) and correlate it with the axial length and refractive error in myopes. Methods: Patients with myopia -1D to -10D attending ophthalmology OPD at a tertiary hospital from October 2013 to April 2015 for evaluation underwent ophthalmic examination including refraction, axial length, and OCT RNFL thickness measurements. The patients were divided into two groups; group A included patients with AL ≤24 mm and group B AL >24 mm. Results: : The study included 100 eyes with myopia ranging from -1D to -10D. The mean (±SD) age was 26.87 (±5.93) years with a range of 21-48 years and male: female ratio of 2:3. There was a statistically significant difference in the average peripapillary RNFL thickness between the two axial length groups (P = 0.01); RNFL thickness in group A being 91.40 (±10.17) and group B 86.06 (±10.09); and in the average RNFL thickness between the 3 degrees of myopia groups, with higher myopic group having thinner RNFL (P = 0.001). Conclusion: There is a significant decrease in RNFL thickness with an increase in the grade of myopia and axial length. This polar RNFL thinning could be wrongly attributed to glaucomatous change. We recommend careful interpretation of RNFL data in myopes with axial length >24 mm, when applying the current OCT nomograms.