A classification of idiopathic epiretinal membrane based on foveal avascular zone area using optical coherence tomography angiography

Figures & data

Figure 1. Stages 1 – 4 of iERM. En-face images (upper row). B-scan images (lower row) (A) Stage 1, FAZ area 0.23 mm² (upper), CMT 296 μm (lower). (B) Stage 2, FAZ area 0.12 mm² (upper), CMT 386 μm (lower). (C) Stage 3, FAZ area 0.06 mm² (upper), CMT 572 μm (lower). (D) Stage 4, FAZ area 0.02 mm² (upper), CMT 715 μm (lower). iERM: idiopathic macular epiretinal membrane; CMT: central macular thickness. (All OCTA scans were acquired in a 3x3mm setting.).

Table 1. Baseline measurements with FAZ area classification.

	Stage 1	Stage 2	Stage 3	Stage 4	F	p
BCVA (logMAR)	0.13 ± 0.15	0.29 ± 0.26	0.46 ± 0.29	0.63 ± 0.29	29.44	< 0.001
CMT (μm)	276.4 ± 56.9	407.4 ± 80.9	522.3 ± 112.5	579.9 ± 116.1	76.37	< 0.001
FAZ parameters
FAZ area (mm^2)	0.24 ± 0.04	0.11 ± 0.02	0.06 ± 0.01	0.02 ± 0.01	584.20	< 0.001
PER (mm)	2.06 ± 0.35	1.40 ± 0.20	1.01 ± 0.15	0.65 ± 0.18	21.34	< 0.001
AI	1.19 ± 0.17	1.19 ± 0.09	1.25 ± 0.29	1.29 ± 0.28	1.58	0.20
FD-300 (%)	47.43 ± 4.66	46.05 ± 5.80	45.71 ± 4.85	45.00 ± 6.93	1.32	0.27

FAZ: foveal avascular zone; BCVA: best-corrected visual acuity; logMAR: log (minimum angle of resolution); CMT: central macular thickness; PER: FAZ perimeter; AI: acircularity index; FD-300: the foveal vessel density in a 300-μm-wide region around the FAZ.

One-way ANOVA tests were used in all statistical analyses.

Figure 2. LogMAR BCVA in pre-  and postoperative iERM eyes with surgery.

The significant differences in pairwise comparison were signed by “*”: * p < 0.05; ** p < 0.01; *** p < 0.001. BCVA: best-corrected visual acuity; logMAR: log (minimum angle of resolution); Pre-op: pre-operation; 1  month post-op: 1 month post-operation; 3  months post-op: 3 months post-operation; 6  months post-op: 6 months post-operation; 1 yearar post-op: 1 year post-operation.

Independent sample t-tests were used in all statistical analyses.

Table 2. LogMAR BCVA in pre-  and postoperative iERM eyes with surgery.

	Pre-op	1 month post-op	3 months post-op	6 months post-op	1 year follow-up
Stage 1	0.27 ± 0.16	0.19 ± 0.09	0.16 ± 0.10	0.15 ± 0.11	0.13 ± 0.09
Stage 2	0.28 ± 0.20	0.25 ± 0.18	0.18 ± 0.18	0.15 ± 0.17	0.11 ± 0.16
Stage 3	0.45 ± 0.29	0.29 ± 0.21	0.22 ± 0.20	0.18 ± 0.17	0.16 ± 0.17
Stage 4	0.60 ± 0.31	0.50 ± 0.30	0.38 ± 0.29	0.34 ± 0.31	0.33 ± 0.34
F	6.44	7,71	4.79	4.90	5.68
P	<0.001	<0.001	0.004	0.003	0.001

BCVA: best-corrected visual acuity; log (minimum angle of resolution); Pre-op: pre-operation; post-op: post-operation; iERM: idiopathic macular epiretinal membrane.

One-way ANOVA tests were used in all statistical analyses.

Figure 3. CMT in pre-  and postoperative iERM eyes with surgery.

The significant differences in pairwise comparison were signed by “*”: * p < 0.05; ** p < 0.01; *** p < 0.001. CMT: central macular thickness; Pre-op: pre-operation; 1  month post-op: 1 month post-operation; 3  months post-op: 3 months post-operation; 6  months post-op: 6 months post-operation; 1 year post-op: 1 year post-operation.

Independent sample t-tests were used in all statistical analyses.

Table 3. CMT (μm) in pre- and postoperative iERM eyes with surgery.

	Pre-op	1 month post-op	3 months post-op	6 months post-op	1 year follow-up
Stage 1	347.8 ± 93.6	347.6 ± 96.4	324.8 ± 77.1	318.2 ± 75.0	281.4 ± 69.5
Stage 2	397.0 ± 62.0	363.5 ± 69.9	348.5 ± 65.0	339.6 ± 66.9	323.1 ± 62.0
Stage 3	527.0 ± 112.2	450.1 ± 82.1	420.3 ± 80.3	407.9 ± 84.7	394.4 ± 87.8
Stage 4	558.3 ± 105.5	479.8 ± 76.7	451.5 ± 75.8	434.7 ± 88.7	410.6 ± 99.4
F	18.00	13.39	11.45	8.29	7.69
P	<0.001	<0.001	<0.001	< 0.001	< 0.001

CMT: central macular thickness; iERM: idiopathic macular epiretinal membrane; pre-op: pre-operation; post-op: post-operation.

One-way ANOVA tests were used in all statistical analyses.

Table 4. Correlation analysis of preoperative logMAR BCVA.

	All		Stage 1		Stage 2		Stage 3		Stage 4
	r	P	r	P	r	P	r	P	r	p
CMT	0.70	<0.001	0.56	<0.001	0.74	<0.001	0.51	<0.001	0.29	0.076
FAZ area	−0.61	<0.001	−0.72	<0.001	−0.17	0.314	−0.13	0.393	−0.13	0.422
PER	−0.39	<0.001	−0.42	0.007	0.12	0.488	0.01	0.976	−0.18	0.274
AI	0.16	0.04	−0.05	0.780	0.32	0.051	−0.09	0.550	0.27	0.095
FD-300	−0.20	0.012	−0.37	0.018	−0.16	0.347	−0.26	0.093	0.05	0.754

BCVA: best-corrected visual acuity; log (minimum angle of resolution); CMT: central macular thickness; FAZ: foveal avascular zone; PER: FAZ perimeter; AI: acircularity index; FD-300: the foveal vessel density in a 300-μm-wide region around the FAZ.

Pearson correlations were used in all statistical analyses.

Table 5. Correlation analysis of 1-year follow-up logMAR BCVA in eyes with surgery.

	All		Stage 1		Stage 2		Stage 3		Stage 4
	r	P	r	P	r	P	r	P	r	P
Baseline BCVA	0.52	<0.001	−0.12	0.851	0.58	0.002	0.39	0.012	0.49	0.004
CMT	0.39	<0.001	0.49	0.402	0.33	0.099	0.44	0.004	0.24	0.191
FAZ area	−0.30	0.002	0.04	0.946	−0.11	0.586	−0.05	0.74	−0.07	0.695
PER	−0.18	0.086	0.15	0.806	−0.04	0.865	−0.15	0.366	−0.15	0.447
AI	0.18	0.067	0.11	0.857	0.18	0.381	−0.16	0.304	0.27	0.135
FD-300	−0.24	0.021	−0.18	0.777	−0.54	0.005	−0.41	0.009	−0.10	0.623

BCVA: best-corrected visual acuity; log (minimum angle of resolution); CMT: central macular thickness; FAZ: foveal avascular zone; PER: FAZ perimeter; AI: acircularity index; FD-300: the foveal vessel density in a 300-μm-wide region around the FAZ.

Pearson correlations were used in all statistical analyses.

Data availability statement

The data supporting this study’s findings are available on reasonable request from the corresponding author, Shen L. However, the data are not publicly available because they contain information that could compromise the privacy of the research participants.