Prevalence and associated factors of refractive errors among type 2 diabetics in Kinmen, Taiwan

A community-based study was conducted to identify the extent of prevalence of refractive errors and their associated factors from among the Chinese type 2 diabetic population in Kinmen.

A total of 547 patients (> 40 years old) with type 2 diabetes were examined with a complete eye screening tests including objective autorefraction. Spherical equivalent refractions of right eyes were reported. Data collected include age, gender, general medical information and serum biochemistry.

The mean refraction was -0.83 +/- 2.49 D. Prevalence rates were determined for myopia (44.1%), hyperopia (24.1%), high myopia (13.0%), and astigmatism (87.8%). Age is an important factor for all of the refractive errors. After adjustment for age, male gender and > 3 grade nuclear opacity appeared to be statistically significant factors for myopia. For hyperopia, > or =7% HbA1c was a significant associated factor, and for astigmatism, > or =200 mg/dl total cholesterol was the risk factor. Multiple linear regression showed that every increase of one year of age and one percent of HbA1c is associated with 0.04 D (p = 0.003) and 0.13D (p = 0.04) shift in hyperopia, respectively. Nuclear opacity with grade 3-4 and grade 5-6 will shift toward myopia of -0.72D (p = 0.02) and -5.34D (p < 0.0001) after adjustment for other risk factors.

This study provides epidemiological data on refractive errors in a Chinese diabetic population in Kinmen, Taiwan. The myopia prevalence is higher than the reported rates in the general population. This survey further confirmed that myopia is more prevalent than hyperopia in the diabetic population. Age and blood sugar shift the refraction toward hyperopia while nuclear cataract reverses it. Correction of refractive errors in the diabetics remained a challenge as not only spectacles but medical intervention is mandatory.