Macular, retinal layers thicker in eyes with vs without diabetic retinopathy
Individuals with diabetic retinopathy (DR) appear to have thicker macula and outer retina compared with those who do not have the diabetic eye disease, and such thickening is more pronounced in eyes with severe DR, according to a study.
The study involved 2,240 eyes from 1,280 patients with diabetes from the Singapore Epidemiology of Eye Diseases Study. Of these, 1,764 eyes (78.7 percent) had no DR, 351 (15.7 percent) had minimal or mild DR, and 125 (5.6 percent) had moderate or worse DR.
Multiple linear regression analysis showed that relative to eyes without DR, those with the diabetic eye disease had thicker macula (245.44 vs 243.04 µm; p=0.03) and outer retina (124.26 vs 123.08 µm; p=0.01). [Br J Ophthalmol 2017;doi:10.1136/bjophthalmol-2017-310959]
When analysis was stratified by DR severity, moderate or worse DR, but not minimal or mild DR, was associated with increased thickness in the macula (250.24 vs 242.88 µm; p=0.011) and outer retina (126.4 vs 123.0 μm; p=0.006) compared with no DR.
“These findings may provide insights into the pathophysiological changes of DR in different retinal layers,” the authors said.
“DR is a leading cause of vision impairment and blindness worldwide, especially in developed countries. [It] has substantial impact on visual function and quality of life of affected individuals,” they continued.
Increasing evidence suggests that neuronal changes, such as neural apoptosis, loss of ganglion cell bodies, and thinner inner retinal layers, may occur prior to the distinct vascular lesions seen in DR (eg, microaneurysms and retinal haemorrhages). [Nat Rev Dis Primers 2016;2:16012; Proc Natl Acad Sci USA 2016;113:E2655–E2664]
Thus, a comprehensive evaluation on the changes in macular thickness, as well as in the ganglion cell-inner plexiform layer and outer retinal thickness, in individuals with diabetes may help shed some light on the pathogenesis of DR, the authors pointed out.
Despite using a large sample size from an Asian population-based study and applying comprehensive and standardised measurements of potential confounders (eg, systemic chronic diseases, non-DR, and macular oedema), one of the study’s weaknesses is its limited statistical power due mainly to the very few cases of severe nonproliferative DR (n=1) and proliferative DR (n=24), they said.
Also, as the study applies a cross-sectional analysis, the present data “cannot ascertain the actual causal relationship between retinal layer thickness changes and DR. Hence, future longitudinal follow-up studies are required to further validate our findings,” the authors added.