Correlation of mean retinal nerve fibre layer (RNFL) thickness with type of refractive error.

Abstract

OBJECTIVE: To evaluate the mean retinal nerve fiber layer (RNFL) thickness in individuals with myopia, hyperopia, and astigmatism and
correlate it with specific refractive error.

METHOD: This comparative cross-sectional study was performed on type of refractive error, included Myopia, Hyperopia, and
Astigmatism. Sixty six eyes of thirty three subjects comprising twenty four eyes with myopia, twenty eyes with hyperopia and twenty two eyes with astigmatism were examined. Optical Coherent Tomogram (OCT) was used to measure RNFL thickness. Data were analyzed with SPSS-25.

RESULTS: Mean RNFL thickness in myopic eye was (92.62 ±8.43) with (SE: -1.00to -7.50), Mean RNFL thickness in Hyperopic eye was (101.25 ± 8.82) with (SE: +0.75 to +3.75). Mean RNFL thickness in Astigmatic eye was (96.95 ±8.23) with (Cyl:-1.00 to -4.00 at 180). The difference between mean RNFL thickness for myopia, hyperopia and astigmatism was statistically significant (One way-ANOVA, f=8.2689, p= 0.0019). There was positive moderate correlation between average RNFL thickness and refractive error (r=0.451). There was very weak positive correlation of average RNFL thickness between myopia (r=0.283), and hyperopia (r=0.118) respectively and positive moderate correlation with astigmatism (r=0.564).

CONCLUSION: RNFL is significantly associated with type of refractive error being thickest for hyperopia and thinnest for myopia. Careful clinical interpretation is a must especially in myopia to avoid misdiagnosis with glaucoma.

KEYWORDS: RNFL, Myopia, Hyperopia, Astigmatism