Axial Length and Optimal Spectacle Correction in Myopia - A Paraxial ABCD-Matrix Simulation Using the Gullstrand-Emsley Schematic Eye

This study models the human eye using the Gullstrand–Emsley schematic eye and ABCD ray transfer matrices to identify the prescription power that minimises retinal blur as a function of axial length. A cascade of 10 optical elements was constructed and a single paraxial ray was traced through it. Axial lengths from 22 mm to 30 mm and corrective lens powers from −14 D to +2 D were simulated using Python. The data demonstrated a strong negative linear correlation between axial length and optimal corrective lens power (R² = 0.9999). Optimal correction reduced retinal blur to approximately 0 mm, demonstrating that ABCD matrices can simulate refractive correction in myopic eyes and provide a transparent illustration of axial-length-based refraction.