Nomogram of peripapillary retinal nerve fiber layer thickness in myopic eyes of north Indian population

Purpose: To evaluate peripapillary-RNFL thickness in myopia by Cirrus OCT among north Indian population by spherical equivalent (SE), age, gender, and axial length (AL). Methods: This was a cross-sectional study held during 2019-2020. Patients aged 18-60 years underwent ophthalmic examination including retinoscopy, AL, and OCT RNFL thickness. Persons with previous ocular surgery or ocular ailment other than refractive error were excluded. The peripapillary-RNFL thickness was noted and compared by demographic determinants. Results: We examined 300 eyes of 300 persons (mean age: 30.75 +/- 8.57 years; 144 males/156 females). Among them, 224 were myopes and 76 were emmetropes (EM). The mean SE was - 3.3 +/- 0.4D (range: -11.0D to + 0.37D). The mean AL was 24.61 +/- 1.92 mm (22.1-29.5). Overall temporal, nasal, superior, inferior, and mean peripapillary-RNFL thickness was 66.31 +/- 7.58, 78.57 +/- 16.00, 120.63 +/- 11.69, 116.60 +/- 15.80, and 95.50 +/- 10.84 mu m, respectively. Temporal, nasal, superior, inferior, and mean peripapillary-RNFL thickness was 73.97 +/- 8.36, 94.84 +/- 7.63, 127.96 +/- 8.96, 136.89 +/- 6.53, and 108.34 +/- 6.28 mu m, respectively, in EM eyes as compared to 63.71 +/- 6.18, 73.05 +/- 14.24, 118.21 +/- 11.53, 109.71 +/- 11.50, and 91.14 +/- 8.31 mu m, respectively, in myopic eyes (P < 0.001). Association of peripapillary-RNFL thickness with myopia and its different grades was P < 0.001. Association of mean peripapillary-RNFL thickness with age was P > 0.005 and gender was P = 0.168. Correlation between SE and RNFL thickness was positive and significant. Correlation between AL and RNFL thickness was negative but statistically significant. Association of AL with SE was P < 0.001. Conclusion: We provide normative peripapillary-RNFL thickness in the north Indian population in order to help in screening for myopia with comorbidity such as glaucoma based on RNFL thickness.