Axial Elongation as a Determinant of Retinal Detachment and Posterior Segment Pathology in High Myopia

Background: High myopia is a progressive ocular disorder associated with axial elongation and degenerative changes in the posterior segment of the eye. Axial length has emerged as a key anatomical determinant of vision-threatening complications, particularly retinal detachment. This study aimed to evaluate axial length variations in high myopia and assess their role in posterior segment changes and retinal detachment outcomes. Methods: This prospective observational study was conducted over one year (July 2023–June 2024) at Department of Ophthalmology, Nandha Medical College and Hospital, Erode, Tamilnadu. A total of 100 patients (200 eyes) with high myopia (spherical equivalent > −6.00 D) were included. All participants underwent comprehensive ophthalmic evaluation, including refraction, best-corrected visual acuity, slit-lamp examination, intraocular pressure measurement, axial length assessment using A-scan ultrasonography, and detailed posterior segment examination. Eyes were categorized into three axial length groups: ≤26 mm, 26.1–30 mm, and >30 mm. Optical coherence tomography and B-scan ultrasonography were performed where indicated. Associations between axial length and retinal findings were analyzed using the Chi-square test. Results: The mean age of participants was 25 ± 5 years, with a slight male predominance. Axial length was ≤26 mm in 64 eyes (32%), 26.1–30 mm in 112 eyes (56%), and >30 mm in 24 eyes (12%), with 68% of eyes showing axial length >26 mm. Posterior segment changes increased significantly with axial elongation. Tessellated fundus was observed in 28%, 61%, and 88% of eyes across the three axial length groups, respectively. Chorioretinal atrophy increased from 6% in eyes ≤26 mm to 75% in eyes >30 mm, while posterior staphyloma was absent in eyes ≤26 mm but present in 42% of eyes >30 mm. Lattice degeneration increased from 14% to 83% with increasing axial length. Retinal detachment was documented in 10 eyes (5%), and notably, all cases occurred in eyes with axial length >26 mm, with a sharp increase to 33% in eyes exceeding 30 mm (p < 0.001). Conclusion: Retinal detachment shows a strong and statistically significant association with increasing axial length in high myopia. Eyes with axial length greater than 30 mm exhibit a disproportionately higher risk of posterior segment degeneration, retinal breaks, and retinal detachment. Axial length measurement is a valuable clinical marker for identifying high-risk myopic eyes and guiding targeted surveillance and preventive strategies