Purpose:
To evaluate the refraction changes over 10 years in the adult Chinese population and to figure out ocular and systematic associations related with the changes.
Methods:
A population-based follow-up study. The Beijing Eye Study was performed in a rural and an urban region of Greater Beijing in the year 2001, 2006, and 2011. A total of 4439 participants (rural: urban 1973:2466) aged over 40 years (56.2±10.6 years) were included at baseline, and 2695 (60.7% of original participants or 66.4% of survivors) were revisited after 10 years. A detailed ophthalmic and medical examination was performed, including ocular biometry, ocular coherent tomography, and systematic measurment. Subjective refraction was applied and the change in spherical equivalent refraction was used for analysis. Systematic and ocular biometry was documented. One eye per subject was enrolled. Eyes with cataract surgery were excluded.
Results:
2508 eyes were included with baseline age of 50.1±9.5 years (male: female 1062:1446). Generally a hyperopic shift (0.15±1.15 diopters, D) was found. For participants aged 40~44, 45~49, 50~54, 55~59, 60~64, 65~69, 70~74, 75~, the mean refraction change (D) was 0.18, 0.35, 0.32, 0.23, 0.03, -0.01, -0.6, -0.5, respectively. Using multivariant analysis, the refractive change was associated with age (P=0.01), baseline refraction (P<0.0001), education background (P=0.02), nuclear cataract (P=0.003), intraocular pressure (P=0.04), and body height (P=0.02). When participants were divided into group with age below 65 and age over 65, the hyperopic trend in people below 65 years old was associated with age (P=0.01), refractive error (P<0.0001), intraocular pressure (P<0.0001); the myopic trend in people over 65 years was associated with refractive error (P<0.0001) and degree of nuclear cataract (P<0.0001). Refractive change was not associated with gender, axial length, corneal thickness, lens thickness, anterior chamber depth, degree of cortical cataract, or degree of sub-capsular cataract.
Conclusions:
Lower intraocular pressure might be a direct or indirect reason for the hyperopic trend in adult Chinese. A myopic trend begins at around 64 years old and was more common in myopic eyes and eyes with nuclear cataract.