En face Integrated Central Avascular Zone (EFICAZ): a noninvasive tool for correlating morphological and functional damage in central diabetic macular edema.

Background: As numerous factors account for diabetic maculopathy, retinal thickness alone is poorly correlated to visual function in diabetic macular edema. En face optical coherence tomography (OCT) enables assessing retinal changes at specific layers. By averaging several planes, overall changes can be better appreciated.

Methods: Retrospective analysis of a consecutive group of 16 patients (30 eyes) with diabetic macular edema in at least one eye, was compared to a control group of 17 healthy subjects (34 eyes). Healthy volunteers and diabetic patients being seen as part of their regular care underwent swept source OCT fundus imaging. En face Integrated Central Avascular Zone (EFICAZ) was manually determined and measured on images obtained by swept-source optical coherence tomography (OCT). EFICAZ was then compared between both populations and, for diabetic patients, correlated with best corrected visual acuity, as measured by the Snellen chart.

Results: In healthy subjects, a moderate correlation was found between age and EFICAZ (Pearson's coefficient = 0.45, P = 0.01). In age-matched populations (mean age of 63 ± 3.8 years for eight healthy subjects and 62.7 ± 8.9 years for diabetic patients; P = 0.9), EFICAZ was significantly higher in diabetic than non-diabetic eyes (2.92 ± 1.10 mm versus 1.86 ± 0.53 mm; P < 0.01). In diabetic patients, correlation between the size of EFICAZ and visual acuity (Pearson's correlation coefficient = -0 .72, P < 0.001) was stronger than between OCT measured central subfield retinal thickness and visual acuity (Pearson's correlation coefficient = -0.02, N.S).

Conclusions: EFICAZ increases with age in normal subjects. It is significantly larger in diabetic than in non-diabetic subjects. It offers a better way to determine visual acuity than OCT measurement of central retinal thickness. This new approach, which takes into account several factors involved in diabetic maculopathy, could be useful in monitoring response to therapy. It can easily be combined with other modalities.