Foveal avascular zone in diabetic retinopathy: quantitative vs qualitative assessment

Abstract

Purpose To describe the relations between foveal avascular zone (FAZ) size and outline in patients presenting diabetic retinopathy. Methods 110 high-quality fluorescein angiograms from 110 diabetics were chosen from our digital retinal image databank. Patients with significant media opacities, macular scars, macular hard exsudates, high ametropia, and associated macular pathology were excluded. Both FAZ perimeter and surface area were measured with image analysis software. FAZ outline was graded according to ETDRS report Number 11 (from 0 ¼ normal to 4 ¼ capillary outline completely destroyed). Data were compared to that of 31 healthy controls. FAZ surface in diabetics was compared to that of controls and FAZ surface was compared to FAZ grade, FAZ perimeter and retinopathy stage in diabetics. Quantitative variables were compared using the U-test of Mann-Whitney or Kruskal-Wallis test and correlations between quantitative variables were estimated with the Spearmann coefficient. Results All patients presented diabetic retinopathy (54 BDR, 30 PPDR, 26 PDR). FAZ size was larger in diabetics than controls (Po0.001). In diabetics, FAZ size increased with FAZ grade (Poor ¼ 0.006 except between grades 1 and 2 ¼ NS) and with retinopathy stage (Poor ¼ 0.024). As retinopathy advanced, there was a higher proportion of altered FAZ outlines (P ¼ 0.003). Conclusions This study confirms capillary alteration to be the cause of increase in FAZ size in diabetics and presents an alternative evaluation method of the FAZ to FAZ size measurement. No qualitative studies using the ETDRS FAZ grading scale have been performed to our knowledge.

An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

“…51 The FAZ area is highly sensitive to ischemic events and is enlarged in conditions such as old age, diabetic retinopathy, RVO, and sickle cell disease. 46,47,[53][54][55][56] The diameter of the FAZ is~400 lm in normal eyes. 51 A recent study found that the FAZ area was~0.373 to 0.377 mm 2 in normal eyes with ICCs >0.9.…”

Evaluation of artifact reduction in optical coherence tomography angiography with real-time tracking and motion correction technology

“…In diabetic retinopathy, residual and distorted lines can complicate detection of key clinical features. Also, high-amplitude pixels contained in line artifacts affect the repeatability of vessel density and non-perfusion area calculation [5,7]. Retinal vessel density is also relevant in conditions such as type 2 macular telangiectasia [36] and retinal vein occlusion [37].…”

“…Recently, the potential for OCTA in clinical evaluation has been demonstrated in vascular diseases such as diabetic retinopathy (DR) [5][6][7][8][9] age-related macular degeneration (AMD) [10][11][12][13] and glaucoma [14][15][16][17]. As OCTA uses the motion of blood cells as intrinsic contrast to identify vascular networks [15,18], it avoids the need for intravenous dye injection.…”

Optical coherence tomography angiography — novel method to access retinal microcirculation in patients with diabetic retinopathy

“…The FAZ is an area surrounding the fovea and completely deprived of vessels, it can only be properly assessed using angiographic images. Physiologically, its surface area peaks at approximately 270 square micrometers and may increase in some vascular diseases of the retina [5].…”