Pathophysiological correlations between fundus fluorescein angiography and optical coherence tomography results in patients with idiopathic epiretinal membranes

Abstract

The aim of the current study was to determine the association between fundus fluorescein angiography (FFA) image results, optical coherence tomography (OCT) imaging results and visual functions in patients with idiopathic epiretinal membranes (ERMs). A total of 80 eyes from 40 patients diagnosed with ERM were analyzed. Best-corrected visual acuity (BCVA) and metamorphopsia were measured using the Early Treatment Diabetic Retinopathy Study eye chart and M-charts, respectively. Macular thickness and volume were determined using OCT. Macular vascular leakage and distortion, and foveal avascular zone (FAZ) diameters were assessed using FFA. BCVA and M-chart results confirmed macular degeneration in the affected eyes. The area of macular vascular leakage was positively correlated with macular volume (r=0.50; P=0.001). The ratio of FAZ diameters was negatively correlated with central macular thickness (r=-0.41; P=0.008). The grade of macular vascular distortion was positively correlated with macular thickness (all r≥0.47; P<0.01) and volume (r=0.53; P<0.001). The results of the current study demonstrated that FFA may effectively identify the degree of changes in retinal macular vasculature. Vascular distortion, measured by FFA, may reflect changes in macular structure and visual functions. These results suggest a potential application of FFA in the pre- and post-surgical evaluation of patients with ERMs.

Keywords: epiretinal membrane; fundus fluorescein angiography; optical coherence tomography; retinal vasculature.

Figure 1.

Measurement of macular vascular leakage by fundus fluorescein angiography. The outline of leakage area in the macula was manually drawn (blue lines) inside the Early Treatment Diabetic Retinopathy Study grid (yellow lines; diameter, 6 mm). Scale bar, 200 µm.

Figure 2.

Visual representation of retinal vascular leakage grading. The images on the left refer to arterial phase, images on the right refer to late phase. Vascular leakage was graded on a scale of 1–4, as defined by the location of hyper-fluorescence. (A) Grade 1, no vascular leakage. (B) Grade 2, vascular leakage only outside the central 1 mm area. (C) Grade 3, vascular leakage only within the central 1 mm area. (D) Grade 4, vascular leakage inside and outside of the central 1 mm area. Arrows present the location of the leakages. Scale bar, 200 µm.

Figure 3.

Visual representation of retinal vascular distortion grading. Vascular distortion in fundus fluorescein angiographs was graded on the extent of straightening and/or distortion in the ellipses (yellow circles). (A) Grade 1, straightening and/or vascular tortuosity limited to a 90° quadrant centered on the fovea. (B) Grade 2, straightening of the retinal vessels within two quadrants. (C) Grade 3, vascular straightening within three quadrants. (D) Grade 4, vascular straightening in all four quadrants. Scale bar, 200 µm.

Figure 4.

Area of leakage is positively correlated with outer ring thickness and macular volume. The correlation between the area of macular vascular leakage by fundus fluorescein angiography and (A) the outer ring macular thickness by OCT or (B) macular volume by OCT. OCT, optical coherence tomography. *Extreme outlier.

Figure 5.

As the central zone thickens, the FAZ ratio decreases. The FAZ and CMT were measured by fundus fluorescein angiography and optical coherence tomography, respectively. FAZ, foveal avascular zone; CMT, central macular thickness.

Figure 6.

Macular vascular distortion is positively correlated with whole macular thickness and volume. Macular vascular distortion (measured by fundus fluorescein angiography) was positively correlated with (A) whole macular thickness and (B) volume (measured by optical coherence tomography). Circles indicate outliers and are labelled with the subject's serial number.

Figure 7.

Macular vascular leakage is positively correlated with macular thickness and volume. Macular vascular leakage (measured by fundus fluorescein angiography) was positively correlated with (A) inner and outer ring thickness, and (B) macular volume (measured by optical coherence tomography).

Figure 8.

BCVA is positively correlated with thicknesses of the central zone and inner ring. BCVA scores positively correlated with (A) CMT and (B) inner ring thickness (measured by optical coherence tomography). CMT, central macular thickness; BCVA, best-corrected visual acuity; logMAR, logarithmically transformed score of the minimal angle of resolution.

Figure 9.

Macular vascular distortion is positively correlated with BCVA and M-chart scores. Macular vascular distortion was measured by fundus fluorescein angiography. BCVA, best-corrected visual acuity. *Extreme outlier.