High myopia associated with retinopathy of prematurity is primarily lenticular

Purpose. To determine which of the eye's refractive components are responsible for the high myopia in retinopathy of prematurity (ROP), as compared with highly myopic eyes in full-term patients. Methods. The study included 53 highly myopic eyes in 34 patients with a history of ROP, and 66 highly myopic eyes in 37 full-term patients. Measurements included refraction, keratometry, and A-scan values for axial length, lens thickness, lens position, anterior chamber depth, anterior segment depth, and lens power calculations. Comparisons were also made with published age-matched, full-term normal controls. Results. Refractions ranged from a spherical-equivalent of -5.0 to -20.75, and from -5.0 to -22.0 diopters in ROP and full-term eyes, respectively. For ROP eyes, increasing myopia was most associated with lens thickness,and lens power (P < 0.001), with lesser contributions from corneal steepness, axial length, and a more forward position of the lens's center. For the eyes with myopia in full-term patients, increasing myopia was highly associated with axial length (P < 0.001), with smaller contributions from increased lens thickness and lens power. ROP eyes had a lens-thickness/anterior-chamber-depth ratio almost 50% higher than FT and normative eyes. Anterior segment depth was remarkably similar in all eyes studied. Conclusions. High myopia associated with ROP appears pathophysiologically distinct from high myopia in full-term patients. The increased lens thickness seen in ROP eyes was accompanied by shallower anterior chamber depth and maintenance of the anterior segment depth, similar to the normal neonatal eye, suggesting a mechanism of altered anterior segment development in ROP leading to high myopia.