gms | German Medical Science

Topopgraphic retinal thickness measurement is suitable for follow-up of diabetic maculopathy. It remains unclear whether retinal thickening occurs earlier in specific areas of the extrafoveal retina.

77 eyes of 77 patients with diabetic retinopathy were studied. 35 normal healthy eyes served as a control group. Clinical classification was done using the international clinical diabetic macular edema disease severity scale. Grade 1: no maculopathy, grade 2: retinal thickening outside the center, grade 3: retinal thickening approching the center, grade 4: retinal thickening involving the center. Optical coherence tomography was performed using the 5 mm radial spoke pattern established for retinal mapping. Retinal thickness measurement was done with a semi-automated, A-scan controlled program specially designed by our group. Differences between clinical grades were measured in 25 different areas and tested for statistical significance by ANOVA.

OCT detected significant differences between clinical grades in superior areas 1,5 mm and in superior and nasal areas 1,5-2,5 mm distant from the fovea. Measurements between grades 1 and 2 were not significantly different, between 2 and 3 only superior (p=0,029) and between 3 and 4 superior and nasal (p=0,000 to p=0,024).

In the presence of clinically significant diabetic maculopathy, differences in retinal thickness outside the focea can be detected by OCT in specific areas (nasally and superior), but these differences become significant only in higher grades of maculopathy. Nevertheless, when assessing diabetic macular edema with OCT, changes of retinal thickness in the superior and nasal areas should be carefully monitored beside the central retinal thickness.