Refractive Errors, Ocular Biometry and Diabetic Retinopathy: A Comprehensive Review

Purpose: To summarize the association between diabetic retinopathy and refractory status as well as ocular biometric parameters; To review the theories of the protective effect of high myopia against diabetic retinopathy. Methods A comprehensive literature search on MEDLINE, EMBASE, Web of Science and Scopus databases as well as reference list search, and systematic review of relevant publications. Results Myopia may delay the onset and progression of diabetic retinopathy. Increased axial length in myopia is associated with reduced risk of any diabetic retinopathy and vision-threatening diabetic retinopathy. The possible mechanisms for the protective effect of myopia against diabetic retinopathy may include posterior vitreous detachment, change in retinal blood flow and oxygen demand, choroidal thinning and altered cytokine profiles. Conclusions High myopia may be a protective factor against the onset and progression of diabetic retinopathy. Further studies about the mechanisms of how myopia, axial length and ocular biometrics influence the onset and progression of DR are needed. retinopathy (DR) is one of the major causes of visual impairment and blindness worldwide. The onset and progression of DR are influenced by systemic factors such as hyperglycemia and hypertension as well as ocular parameters. A better knowledge of the risk factors for DR is vital to improving the outcome of patients with DR and risk stratification. More recently, there has been increasing focus on the influence of myopia on DR development. Some observational studies have reported myopia being a protective factor for the development of DR, however, the findings were inconsistent. In addition, it remains unclear whether it was myopia, axial length (AL), or other refractive factors that play a protective role. The protective mechanism against DR may be related to ocular elongation, posterior vitreous detachment, low perfusion in the retina and the abnormal cytokine profile. This systematic review will summarize the association of DR with refractory status as well as different refractive components including anterior chamber depth, refractory power of the lens, AL, and axial length-to-corneal radius ratio.