Evaluation of macular neovascularization activity in pathological myopia: a comparison between optical coherence tomography and OCT-angiography

Abstract

Purpose: The purpose of this study was to suggest a novel approach to assessing the activity of macular neovascularization (MNV) in pathological myopia (PM) by comparing optical coherence tomography (OCT) with OCT-angiography (OCT-A).

Methods: The Zeiss Cirrus HD-5000 was used to obtain OCT and OCT-A images of PM-MNV. The objective was to examine the characteristics of PM-MNV lesions and investigate the relationship between PM-MNV activity and changes in retinal structure in 54 patients (54 eyes). To analyze the OCT parameters associated with PM-MNV activity and their clinical significance in terms of sensitivity and specificity, we used OCT-A as a reference.

Results: This study included 72 patients (72 eyes), of whom 54 had good image quality and were considered for analysis. The study evaluated various OCT characteristics of MNV lesions, including the elevation of an external limiting membrane (ELM), ellipsoidal zone (EZ), retinal pigment epithelium (RPE) elevation, and EZ/RPE interruption, to identify possible parameters associated with PM-MNV activity. The interobserver consistency was found to be almost perfect. In the evaluation of PM-MNV activity, the sensitivity of ELM elevation, EZ interruption, and RPE interruption was found to be 66.7% (low), 88.4% (high), and 95.6% (high), respectively. However, the specificity was found to be 71.4% (moderate), 71.4% (moderate), and 25.4% (poor), respectively. This indicates that the current evaluation methods are not accurately assessing PM-MNV activity. We developed a new comprehensive method that used EZ interruption as the primary parameter and ELM elevation and RPE interruption as secondary parameters to evaluate PM-MNV activity with a sensitivity of 97.8% and a specificity of 85.4%.

Conclusion: In PM-MNV, a novel comprehensive diagnostic method combining EZ interruption, ELM elevation, and RPE interruption might be a valuable indicator to evaluate PM-MNV activity.

Keywords: OCT-angiography; activity; macular neovascularization; optical coherence tomography; pathological myopia.

Figure 1

Diagram displaying the zone of interest. The fovea zone was defined by a circle with a 1-mm diameter. The parafovea zone was defined by a ring with a 0.5–1-mm radius in the center of the fovea zone.

Figure 2

Retinal structure images on optical coherence tomography. The red line showed the external limiting membrane (ELM). The yellow line shows the ellipsoidal zone (EZ). The green line showed the retinal pigmental epithelium (RPE).

Figure 3

Definition of outer retinal characteristics associated with MNV activity using OCT. Subretinal hyperreflective exudation was defined as the presence of areas of high reflectivity that are located outside the RPE but within the retinal pigment epithelium [⋆ in (A)]. EZ/ELM interruption was defined as the absence or discontinuity of EZ/ELM hyperreflective lines above MNV lesions [(A), green arrow]. EZ/ELM elevation was defined as elevated EZ/ELM hyperreflective lines above MNV lesions (B) (EZ, yellow arrow; ELM, red arrow). RPE elevation was defined as a highly reflective band over the MNV lesions on OCT and was continued with the RPE monolayer [(C), blue arrow]. RPE interruption was identified in (A).

Figure 4

Optical coherence tomography angiography images of macular neovascularization (MNV) in pathological myopia (PM). OCT-A image of PM-MNV, which can clearly see MNV morphological characteristics, including its primary appearance as medusa or sea-fan shaped (A, B), numerous microcapillaries (B, C), and the presence of loops/anastomoses [(C), yellow arrow].