Prevalence of myopia and its association with diabetic retinopathy in subjects with type II diabetes mellitus: A population-based study

Abstract

Objective:To report the prevalence of myopia and its association with diabetic retinopathy in subjects with type II diabetes mellitus and compare the diabetic retinopathy status in the myopic group vs the emmetropic group.Design:Population-based study.Materials and Methods:The population-based study estimated the prevalence of myopia from 1058 subjects, who were more than 40 years old and had type II diabetes mellitus; the patients were enrolled from a cross-sectional study. Participants answered a detailed questionnaire and underwent biochemical, physical and comprehensive ocular examination which included grading of nuclear sclerosis by lens opacities classification system III (LOCS III), seven field fundus photography and ultrasonography. Diabetic retinopathy and diabetic maculopathy were graded using the Klein's classification and early treatment diabetic retinopathy study (ETDRS) criteria respectively.Results:The prevalence of mild, moderate and high myopia in type 2 diabetes was 15.9, 2.1 and 1.9% respectively. The prevalence of any myopia was found to be 19.9% in our study population. After adjusting the age, gender, duration of diabetes, hemoglobin A1c and other factors, increasing age was associated with mild and moderate myopia [OR 1.11 (95% CI 1.05 – 1.18)]. Compared to emmetropia, complete posterior vitreous detachment (CPVD) was associated with high myopia (50% Vs 12.2%, P < 0.0001). Myopia had no association with diabetic retinopathy.Conclusion:The prevalence of myopia and high myopia was found to be 19.9 and 1.9% respectively among subjects with type II diabetes. Myopia was not associated with diabetic retinopathy, thereby, suggesting the need for a longitudinal study.

High myopia is protective against diabetic retinopathy via thinning retinal vein: A report from Fushun Diabetic Retinopathy Cohort Study (FS-DIRECT)

“… 11 However, date from other epidemiology studies, including Chinese population-based studies, did not find this protective effect of myopia. 2 , 19 – 21 , 32 , 33 Although the longitudinal results of BES found that the incidence of DR was associated with shorter axial length, the refraction was never found to be associated with prevalence/incidence of DR. 2 , 21 Similarly, Man et al found that the longer axial length rather than myopia was the main contributor for the protective effect. 32 , 33 The inconsistent findings may be due to different definitions or classifications of myopia, methodology of fundus photography and definitions of DR.…”

“…Myopia was suggested as a protective factor for DR in population-based studies, clinical studies and meta-analysis. 11 – 18 However, several studies have denied the protective effect for myopia against DR. 2 , 19 – 21 Regarding the association in Chinese population, data are limited and remain controversial. 2 , 13 , 21 In the Beijing Eye Study (BES) with a moderate sample size (n = 362), Xie et al found that neither the prevalence of DR nor the stage of DR was associated with refractive error.…”

Expression of Osteopontin and Integrin αvβ3 Receptor in Retina of Diabetic Guinea Pigs with High Myopia

“…Therefore, we suspect that high myopia inhibits the expression of OPN and plays a protective role in DR. However, few studies assert the contrary; Ganesan et al [24] did not find a significant association between high myopia and DR.…”

The Relation between High Myopia and Diabetic Retinopathy

“…Although the exact mechanism(s) underlying the protective effect of high myopia against DR is yet to be defined but some studies shows the protective effect of axial length against DR was due to several hypotheses, one hypothesis is that with axial elongation there is narrowing of blood vessels in the retina leading to reduction in retinal blood flow according to Hagen-Poiseuille law resulting in a decrease in capillary hydrostatic pressure and consequent decreased likelihood of leakage and rupture of compromised retinal capillaries in diabetes (Starling and Laplace's law), [28] deformation in the posterior pole, [20] increased ocular volume in an elongated eye, [29] neurodegeneration, neuron dysfunction, [30] thinning of the peripheral retina [30] in axially elongated eyes with resultant decreased metabolic demand then could blunt the hypoxic response which is necessary for diabetic retinopathy, [30] a reduction in vascular endothelial growth factor concentration in the aqueous associated with increasing axial length, [31] an impairment of retinal adaptive circuitry in myopic eyes [32] that might be associated with abnormal reduction of inner retinal function [20] and the development of posterior vitreous detachment [33] that removes the vitreous scaffold for neovascular proliferation and enhances oxygen diffusion across the liquefied vitreous [17] .…”