Abstract
Purpose:
High myopia is a major cause of blindness and vision impairment. This study was initiated to evaluate the occurrence of retinal pathology in highly myopic eyes and its impact on visual impairment.
Methods:
Nine hundred and seventeen participants aged between 7 to 70 years with myopia ≥ -6.00 D in both eyes were recruited from the Zhongshan Ophthalmic Centre clinic for this ZOC-BHVI High Myopia Study. The mean age of participants was 22.1 ± 12.5 years. Exclusion criteria included any systemic or ocular conditions including syndromic high myopia, previous ocular surgery, optical or therapeutic treatment for myopia. Ocular parameters measured in both eyes were: cycloplegic autorefraction, subjective refraction, best corrected visual acuity (BCVA), and axial length (AL) using partial coherence interferometry. Retinal findings were confirmed by slit lamp fundus examination, using 3-mirror fundus lens, and recorded as A. normal; B. abnormal (categories: a. retinal break; b. macular oedema; c. posterior staphyloma; d. retinal detachment). Vision was classified as: Normal Vision (≥ 1.0); Mild Vision Impairment (<1.0 to <0.3); Moderate Vision Impairment (0.3 to ≥0.1); Severe Visual Impairment (<0.1 to ≥0.05) and Blindness (<0.05). Proportion of retinal pathology among the eyes by the categories of age group, spherical equivalent and axial length was calculated.
Results:
Data from 1686 eyes (843 participants; 442 female) were analysed. The mean spherical equivalent (SE) was -9.30 ± 2.9 D (range: -6.00 to -29.80 D); axial length - 27.2 mm ± 1.4 (range 23.8 to 31.8 mm). Myopic retinal pathology was seen in 13.3% (224 eyes). The prevalence of retinal pathology ranged from 5% for age <15 years to 51% for those up to 55 years; 6% for ALs up to 24 mm up to 54% for 32 mm; 5% for -6 D of myopia to up to 65% for -39 D (see Figure1). Proportions of vision impairment among the eyes with retinal pathology were: no VI, 57.0%; mild VI, 40.4%; moderate VI, 2.3% and 0.4% were blind. Multiple logistic regression with robust estimation of variance indicated that age and axial length were the most powerful associates for retinal pathology
Conclusions:
The prevalence of retinal pathology increases with increasing age, axial length and refractive error. Retinal pathology may be present in eyes with high myopia even when there is no, or only mild vision impairment