We enrolled 1026 high myopia patients with cataracts and 2136 controls (age-matched) with only high myopia from Xi’an Fourth Hospital (Figure 1). All participants were high myopia patients and unrelated Han Chinese individuals (at least all 3 generations were of Han descent and had no history of migration). All participants were examined by detailed ophthalmic assessments. According to the spherical equivalent (SE) of both eyes, high myopia was defined by SE ≤−6.0 dioptres (D). Those having both eyes meeting the criteria were included. Those with prior ocular surgery, ocular trauma, strabismus, corneal or ocular surface diseases, corneal scar, uveitis, glaucoma, or other major eye diseases affecting the accuracy of refraction were excluded from the study. Ocular lens opacification and best-corrected visual acuity less than 20/40 were used to diagnose cataracts. According to the lens opacity area of the enrolled patients, cataracts were divided into 4 types: cortical cataracts, nuclear cataracts, posterior subcapsular cataracts, and mixed cataracts. If the enrolled patient had at least 1 eye with more than 1 type of cataract or 2 eyes with different types, he or she was defined as the mixed type. Patients meeting the following criteria were included in the case group: (1) lens opacity; (2) under 50 years old (excluding age-related cataracts); (3) best-corrected visual acuity below 20/40; and (4) no other clear causes of cataracts. Patients with complicated cataracts caused by diabetes or other known causes, as well as with pseudophakia or aphakia in either eye, were also excluded from the study.
The study participants’ peripheral blood samples were drawn, conserved, and used in subsequent genotyping. Table 1 displays the clinical features and demographic data of the study participants that were gathered through questionnaires and medical records. Each participant provided their written informed consent. The Medical Ethics Committee of Xi’an Fourth Hospital approved the study.