Increased Foveal Avascular Zone in Diabetic Retinopathy Patients Detected Non-Invasively by the Retinal Function Imager

Abstract

 

Purpose:

 

To non-invasively measure and compare the foveal avascular zone (FAZ) in healthy subjects and diabetic retinopathy (DR) patients. We used the Retinal Function Imager (RFI, Optical Imaging, Ltd) to image the retinal vascular network.

 

Methods:

 

Fourteen eyes of 11 DR patients and 22 eyes of 18 healthy subjects were recruited. Multiple RFI retinal image series (each made of 8 images, 55 Hz) were acquired from each subject. Following registration, pixel values were analyzed to locate blood motion, thus obtaining non-invasive capillary perfusion maps (nCPM) at high resolution. FAZ dimensions were measured using ImageJ 1.42q (NIH, USA). Comparison between groups was done using student t-test.

 

Results:

 

The average FAZ area in patients with DR was significantly larger compared to controls (0.21±0.07 vs 0.13±0.06 mm², p<0.001), as was the FAZ diameter (657±72 vs 480±95 µm, p<0.001) (Fig. 1).

 

Conclusions:

 

Using the RFI we detected a significantly enlarged FAZ area in patients with DR, which represents the ischemic process in the diabetic eye. Non-invasive and safe monitoring of the FAZ dimensions may provide an important tool for early diagnosis, follow-up and tailoring treatment in diabetic patients.Fig. 1 nCPMs of (A) a Healthy subject; (B) a DR (diabetic retinopathy) patient. Area and diameter of FAZ: (A) 0.114mm², 464µm; (B) 0.225 mm², 672µm. The green line encircles the FAZ.  

 

Keywords: imaging/image analysis: clinical • diabetic retinopathy