J Korean Ophthalmol Soc.  2017 Aug;58(8):952-959. 10.3341/jkos.2017.58.8.952.

Optical Coherence Tomography-angiography: Comparison of the Foveal Avascular Zone between Diabetic Retinopathy and Normal Subjects

• Kim IG
• Lee JE

• KMID: 2388184
• DOI: http://doi.org/10.3341/jkos.2017.58.8.952

Abstract

PURPOSE
To evaluate the effectiveness of optical coherence tomography angiography (OCTA) in investigating changes in the area of the foveal avascular zone (FAZ) in patients with diabetic retinopathy (DR) and normal subjects.
METHODS
Eighty-five eyes of 50 DR patients and 50 eyes of 25 normal subjects were included. OCTA images of the FAZ were acquired using the split-spectrum amplitude decorrelation angiography algorithm of Optovue Avanti RTVue XR OCT. Patients were divided into three groups according to DR severity: mild-to-moderate non-proliferative diabetic retinopathy (NPDR) group, severe NPDR group, and proliferative DR group. The area of the FAZ was measured using built-in software and was compared between the patients and normal subjects and among the three groups.
RESULTS
The area of the FAZ in patients with diabetic retinopathy (0.46 mm²) was significantly larger than that in normal subjects (0.30 mm², p = 0.001). A significant difference was observed depending on DR severity: 0.40 mm² in the mild-to-moderate NPDR group, 0.45 mm² in the severe NPDR group, and 0.53 mm² in the PDR group (p = 0.03). Correlation between area of the foveal avascular zone and visual acuity showed a tendency toward reduction in visual acuity (p = 0.002).
CONCLUSIONS
OCTA effectively detected changes in the FAZ area in DR patients. OCTA has the potential to be used for noninvasive quantification and monitoring of the FAZ.

Keyword

Diabetic retinopathy; Foveal avascular zone; Optical coherence tomography angiography

MeSH Terms

Angiography
Diabetic Retinopathy*
Humans
Tomography, Optical Coherence
Visual Acuity

Figure

• 

  Figure 1. Foveal avascular zone (FAZ) measured by optical coherence tomography angiography. Optical coherence tomog-raphy angiography clearly shows the area of the FAZ of the su-perficial retinal capillary plexus around the fovea. The margin of the FAZ was automatically demarcated and the area was measured by the built-in software.

• 

  Figure 2. Optical coherence tomography angiography images of normal individuals and patients with diabetic retinopathy. (A) The foveal avascular zone (FAZ) in healthy individuals was round in shape and had regular borders (arrow). (B) The FAZ in patients with diabetic retinopathy had irregular borders (arrow). The pathologic capillary nonperfusion area was also frequently found outside the FAZ (arrowhead). The area of the FAZ in patients with diabetic retinopathy (B) was significantly larger than that in normal subjects.

• 

  Figure 3. Comparison of the size of the foveal avascular zone (FAZ) according to diabetic retinopathy severity. Representative pho-tographs of the mild-to-moderate non-proliferative diabetic retinopathy (NPDR) (A), severe NPDR (B) and proliferative diabetic retinopathy (C) groups. A significant difference in the size of the FAZ was seen among the three groups.

• 

  Figure 4. Correlation between the foveal avascular zone and visual acuity. It showed a tendency towards reduction in visual acuity (Pearson correlation coefficient = 0.392, p = 0.002). BCVA = best corrected visual acuity; FAZ = foveal avascular zone; logMAR = logarithm of minimum angle of resolution.

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