Anatomical changes in idiopathic epiretinal membrane at 2-year follow-up assessed using spectral domain optical coherence tomography and optical coherence tomographic angiography

PURPOSE

To evaluate anatomical changes in the low-stage partial attachment-type idiopathic epiretinal membrane (iERM) over 2 years.

METHODS

Data from patients with low-stage partial attachment-type iERM (stage 2) were analyzed. The main outcome measures were anatomical changes, including changes in the foveal avascular zone (FAZ) area, vessel density (VD) in the vascular plexus, and thickness of retinal sublayers during the follow-up period.

RESULTS

Thirty patients (mean age: 68±12 years) were included in the study. The FAZ area on the superficial vascular plexus (SVP) significantly decreased from baseline (0.12±0.08 mm2) to month 24 (0.10±0.08 mm2, p=0.024). However, the FAZ area on the deep vascular plexus (DVP) did not significantly decrease from baseline (0.15±0.13 mm2) to month 24 (0.14±0.14 mm2, p=0.099). VDs on both the SVP and DVP did not show significant change from baseline (29.51±8.14% vs. 28.35±5.63%) to month 24 (29.79±9.77%, p=0.564 vs. 28.17±5.75%, p=0.417). Parafoveal ganglion cell and inner plexiform layer (GCIPL) thickness decreased from baseline (108.77±13.61 μm) to month 24 (103.03±15.54 μm, p=0.004). The central total retinal layer thickness did not significantly change from baseline (396.07±64.86 μm) to month 24 (392.04±72.72 μm, p=0.570).

CONCLUSION

Even in low-stage ERM, inner retinal changes, including GCIPL thickness, occurred during follow-up periods, which might be owing to degenerative changes or centrifugal movement.

The repeatability of superficial retinal vessel density measurements in eyes with long axial length using optical coherence tomography angiography

BACKGROUND

To investigate the repeatability of superficial retinal vessel density measurements in healthy eyes with long axial length (AL) using optical coherence tomography angiography (OCTA).

METHODS

There were 60 eyes of 31 volunteers enrolled in this cross-sectional observational study. All subjects underwent OCTA, AL and refraction test. The enrolled eyes were divided into the long AL group (26 mm ≤ AL < 28 mm) and normal AL group (22 mm ≤ AL < 26 mm). The vessel length density (VLD), perfusion density (PD), and fovea avascular zone (FAZ) of the superficial retinal vessel were evaluated. Repeatability was assessed by intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Pearson's r correlation was used to analyze the relation of AL and the absolute difference between two measurements.

RESULTS

The 3 × 3 mm scan pattern showed good repeatability with all ICCs over 0.7. For all parameters of all scan patterns, the ICCs of the normal AL group were distinctly higher than those of the long AL group; this finding was also confirmed by Bland-Altman analysis. The correlation analysis of AL and repeatability of OCTA parameters showed significant negative correlations between the ALs and repeatability of VLD in 6 × 6 mm inner ring (r² = 0.13, p = 0.01), VLD in 6 × 6 mm outer ring (r² = 0.09, p = 0.02) and PD in 6 × 6 mm outer ring (r² = 0.08, p = 0.03).

CONCLUSIONS

The AL and the scanned area will both affect the repeatability of superficial retinal vessel density measurements in OCTA.