Association of Sub-Choroidal Thickness with Refractive Error and Axial Length in Myopia and Emmetropia: An OCT Scan Study

Abstract

Aim: To find out the correlation of choroidal thickness (CHT) with refractive error (RE) & axial length (AL) in North-Indian population of age group of 18-35 years having myopia or emmetropia using A-scan and Oct imaging.

Objective is to check for a relationship of CHT with AL & RE in myopic – emmetropic individuals with help of A-scan and Oct imaging.

Methods this study is an observation- analysis based cross sectional study which involved 200 eyes of individuals presented at outpatient department of Eye care solution consisting 50 beings with ≥4 D Myopia & 50 other Emmetropic presenting for ailments other than refractive error taken as Control group. The criteria for selection of subjects were done on basis of selective age 18-35 years, degree of refractive error and clear ocular media. However, subjects with history of any intraocular pathology, surgery, inflammation or any associated systemic disorder such or vascular diseases were excluded another thing where in person with OCT scan less signal strength, motion artifact & focal signal loss were too excluded. A written-informed consent was taken from all subjects prior to enrolment.

Results: This study investigated the structural characteristics of the eye across three groups of myopic individuals and a control group. Myopia Group I (with myopia ranging from -3.00 D to -4.75 D) showed an average axial length of 24.78 mm, macular thickness of 100.08 µm, and choroidal thickness of 309.54 µm. Myopia Group II (with myopia between -5.00 D and -6.75 D) exhibited a greater axial length of 25.83 mm, a macular thickness of 112.34 µm, and a choroidal thickness of 289.47 µm. Myopia Group III (with myopia of -7.00 D and above) had the longest axial length at 26.10 mm, a macular thickness of 110.38 µm, and the thinnest choroidal thickness at 255.38 µm. In comparison, the control group, consisting of emmetropic individuals, had an average axial length of 23.26 mm, macular thickness of 322.24 µm, and a significantly thicker choroid (242.23 µm) across both Sattler’s and Haller’s layers. These findings highlight the progressive structural changes—particularly axial elongation and choroidal thinning—associated with increasing myopia severity.

Conclusion: The results of this study reveal a definite link between the degree of myopia and anatomical variations in the eye. Axial length increases in tandem with myopia, and the choroid significantly thins, especially in the deeper layers (Sattler's and Haller's). According to these results, axial elongation and choroidal thinning are progressive features of myopia, with alterations becoming more noticeable as refractive error increases. Gaining knowledge of these structural changes may help direct future treatment approaches and offer significant understanding into the pathophysiology of myopia