Korean J Ophthalmol.  2015 Jun;29(3):168-172. 10.3341/kjo.2015.29.3.168.

Simplified Correction of Ischemic Index in Diabetic Retinopathy Evaluated by Ultra-widefield Fluorescein Angiography

• Kim JH
• Jung HG
• Chung HJ
• Lee K
• Sohn J

• KMID: 2363754
• DOI: http://doi.org/10.3341/kjo.2015.29.3.168

Abstract

PURPOSE
To develop a novel, simplified method for correcting the ischemic index of nonperfused areas in diabetic retinopathy (DR).
METHODS
We performed a retrospective review of 103 eyes with naive DR that underwent ultra-widefield angiography (UWFA) over a year. UWFAs were graded according to the quantity of retinal non-perfusion, and uncorrected ischemic index (UII) and corrected ischemic index (CII) were calculated using a simplified, novel method.
RESULTS
The average differences between UII and CII in the non-proliferative DR group and the proliferative DR group were 0.7 +/- 0.9% in the <25% CII group, 3.0 +/- 0.9% in the 25% to 49.9% CII group, and 3.6 +/- 0.6% in the >50% CII group, respectively. A CII >25% was critical for determining DR progression (p < 0.001).
CONCLUSIONS
Distortion created by UWFA needs to be corrected because the difference between UII and CII in DR increases with the ischemic index.

Keyword

Diabetic retinopathy; Ischemic index; Wide-field fluorescein angiography

MeSH Terms

Adult
Aged
Aged, 80 and over
Diabetic Retinopathy/*diagnosis/pathology
Female
Fluorescein Angiography/*methods
Humans
Ischemia/pathology
Male
Middle Aged
Retinal Vein/pathology
Retrospective Studies
Sensitivity and Specificity

Figure

• 

  Fig. 1 Schematic drawing of the retina and ultra-widefield angiography image. The more peripheral the retina, the greater the distortion of the projected image, resulting in a discrepancy with the actual retina size. θ = median angle of each zone; a = length of the retinal arc on ultra-widefield angiography; sin θ = d / r; d = r × sin θ; a = 2πr × θ / 360°; and d / a = (360° × sin θ / 2πθ).

• 

  Fig. 2 Ultra-widefield fluorescein angiography images of non-proliferative diabetic retinopathy (A) and proliferative diabetic retinopathy (B) used for calculating ischemic index. Each zone is numbered from 1 to 10, and the areas of non-perfusion are shaded.

• 

  Fig. 3 Mean difference (%) of corrected ischemic index in each range (a) to (c). There was a statistically significant difference between each range.

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