The OCT Angiography Revolution: Five Emerging Themes

Video Color OCT Angiography for Myopic Choroidal Neovascularization

PURPOSE

To investigate the myopic macular neovascularization (mMNV) features on dynamic video color OCT angiography (OCTA) and the diagnostic rate versus the static, 4-segmentations visualization mode.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Fifty-four patients with mMNV.

METHODS

Sixty-two eyes with high myopia complicated by mMNV were included. Clinical charts, fluorescein angiography, and structural OCT were used as standard references to assess lesion activity. Static and video color OCTA were then analyzed and compared by 2 independent reviewers.

MAIN OUTCOME MEASURES

Morphology description of mMNV on video color OCTA and differences in the proportion of diagnosis between video color and static OCTA.

RESULTS

Sixty-two eyes from 54 patients (mean age, 63.22 years) were enrolled. Thirty-four (55%) mMNVs were active and 28 (45%) inactive. Twenty-two (65%) active mMNVs presented on video color OCTA as an interlacing vascular network in the outer retina and the choriocapillaris. A tapered form was the prevalent size (72.7%). In 3 eyes (9%), an abnormal and irregular vascular network (AVN) was disclosed and in 5 (15%) only some blood flow alteration. All the lesions extended in both the outer retina and the choriocapillaris. Eleven (39%) inactive mMNVs also presented on video color OCTA as an interlacing vascular network in the outer retina and the choriocapillaris. Eight (29%) inactive mMNVs had some AVN, and 6 (21%) only some blood flow alteration. The diagnostic rate of video color versus static OCTA was 95% (95% confidence interval [CI], 86%-99%) versus 77% (95% CI, 86%-99%; P = 0.0009), and showed an advantage in favor of video color OCTA of 15% (95% CI, 3%-27%) and 22% (95% CI, 7%-38%) in active and inactive lesions, respectively (P < 0.026). Lesion extension within both the outer retina and the choriocapillaris was present in 90% and 69% of cases on dynamic OCTA and static OCTA, respectively, with a proportion difference of 20% (95% CI, 10%-31%; P = 0.0005). Concordance between the 2 examiners was high: 0.95 (95% CI, 0.88-1.00) and 0.96 (95% CI, 0.91-1.00) for active and inactive lesions, respectively.

CONCLUSIONS

Video color-enhanced OCTA may help in diagnosing mMNV and should be considered in addition to structural OCT and static OCTA.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Customized Slab-Segmentation Method for Projection-Artifact Elimination in Best Vitelliform Macular Dystrophy: A Swept-Source Optical Coherence Tomography Angiography Study

Purpose

To assess the efficacy of customized slab segmentation in eliminating projection artifacts in swept-source optical coherence tomography angiography (SS-OCTA) images of Best vitelliform macular dystrophy (BVMD).

Methods

Prospective case series including different stages of BVMD. We analyzed SS-OCTA images for flow signals in the outer retina and coregistered B-scan images for distortion of the segmentation slabs defining the outer retina. We applied a customized method for slab realignment whenever BVMD lesions produced distortion of the slabs. Afterward, we checked the images to determine whether the previously noted flow signal had persisted or disappeared, described as “true flow” or “pseudoflow”, respectively. Categorical variables were analyzed with X² or Fisher’s exact tests, while quantitative variables were analyzed with independent t-test at p<0.05.

Results

The study included 39 eyes of 22 patients. We detected BVMD patterns I (dome-shaped hyperreflective lesion without neurosensory retinal detachment), II (knob-like hyperreflective lesion with localized neurosensory retinal detachment), and III (heterogeneous scattered hyperreflective material) in 49%, 23%, and 28% of eyes, respectively. Pseudoflow was evident mostly in eyes with pattern II lesions, presence of flow signal within BVMD lesions, and lesions whose height represented >80% of the retinal thickness (p<0.001).

Conclusion

Customized slab segmentation is effective in eliminating projection artifact in SS-OCTA images of BVMD.

Summary

Projection artifact is a significant confounding factor in emerging SS-OCTA technology through production of pseudoflow signals that can lead to misinterpretation of images of BVMD lesions. The present study proposes a customized method for correction of segmentation errors to eliminate projection artifacts in SS-OCTA images of BVMD patients.