Swept source optical coherence tomography analysis of choroidal thickness in macular telangiectasia type 2: a case-control study

Advances in swept-source optical coherence tomography and optical coherence tomography angiography

Background

The fast development of swept-source optical coherence tomography (SS-OCT) and swept-source optical coherence tomography angiography (SS-OCTA) enables both anterior and posterior imaging of the eye. These techniques have evolved from a research tool to an essential clinical imaging modality.

Main text

The longer wavelength and faster speed of SS-OCT and SS-OCTA facilitate better visualization of structure and vasculature below pigmented tissue with a larger field of view of the posterior segment and 360-degree visualization of the anterior segment. In the past 10 years, algorithms dealing with OCT and OCTA data also vastly improved the image quality and enabled the automated quantification of OCT- and OCTA-derived metrics. This technology has enriched our current understanding of healthy and diseased eyes. Even though the high cost of the systems currently limited the widespread use of SS-OCT and SS-OCTA at the first beginning, the gap between research and clinic practice got obviously shortened in the past few years.

Conclusions

SS-OCT and SS-OCTA will continue to evolve rapidly, contributing to a paradigm shift toward more widespread adoption of new imaging technology in clinical practice.

Choroidal vascularity index: an enhanced depth optical coherence tomography-based parameter to determine vascular status in patients with proliferative and non-proliferative macular telangiectasia

KEY MESSAGES

The pathogenesis of subretinal neovascularization (SRNV) due to macular telengiectasia (MacTel 2) has not fully elucidated. This optical coherence tomography (OCT)-based method can provide better understanding of the pathogenesis of SRNV due to MacTel 2.

PURPOSE

To evaluate the choroidal vascular index (CVI) through optical coherence tomography (OCT) on eyes with proliferative macular telangiectasia type 2 (MacTel 2) or non-proliferative MacTel 2, and in healthy individuals.

METHODS

Macular enhanced depth imaging OCT scans on 42 eyes of 21 patients with non-proliferative MacTel 2, on 32 eyes of 20 patients with proliferative MacTel 2, and on 38 eyes of 32 control patients were analyzed by adjusting for age-gender-axial length. Proliferative MacTel 2 was diagnosed when subretinal neovascularization (SRNV) was simultaneously observed in the non-proliferative phase. Binarization methods of ImageJ software were used to analyze images, and total choroid area (TCA), luminal area (LA) and stromal area (SA) were obtained. CVI was characterized as the ratio of LA to TCA.

RESULTS

The mean TCA and SA were significantly higher in group 1 and group 2 when compared with group 3 (3.36 ± 0.29 mm² vs. 3.27 ± 0.76 mm² vs. 2.49 ± 0.24 mm², p < 0.001; 1.15 ± 0.31 mm² vs. 1.10 ± 0.69 mm² vs. 0.35 ± 0.23 mm², respectively; p < 0.001). Although LA was relatively higher in group 1 and group 2 than group 3, no statistically significant difference was observed (2.22 ± 0.14 mm² vs. 2.17 ± 0.15 mm² vs. 2.13 ± 0.21 mm²) (p = 0.088). CVI was significantly lower in group 1 than other groups (0.65 ± 0.01 vs 0.67 ± 0.02 vs 0.68 ± 0.02) (p < 0.001).

CONCLUSION

As an OCT screening method, CVI may be used to assess the vascular status of the choroid on the eyes which are naive for or were exposed to SRNV secondary to MacTel 2, and to elucidate the pathogenesis of this disease.

Evaluation of Choroidal Thickness in Patients with Proliferative and Non-Proliferative Macular Telangiectasia Using Enhanced Depth Imaging Optical Coherence Tomography

Purpose: To compare subfoveal choroidal thickness (SFCT) in eyes with non-proliferative macular telangiectasia (MacTel) type 2 with or without subretinal neovascularization (SRNV) and healthy control eyes.Methods: Consecutive patients with non-proliferative and proliferative MacTel type 2 were included in the current study. For comparisons subjects with no ocular pathology were recruited and used as controls. Best corrected visual acuity (BCVA), central macular thickness (CMT), and subfoveal choroidal thickness (SFCT) were evaluated. Since axial length (AL) may affect choroidal thickness, AL measurements were performed to avoid confusion in SFCT between the groups.Results: Of the 63 eyes of 38 MacTel type 2 patients, 38 eyes had only MacTel type 2 (group 1) and 25 eyes had SRNV caused by MacTel type 2 (group 2). Fourty eyes of 20 subjects served as controls (group 3). BCVA was found to be significantly higher in control group compared with group 1 and group 2 (p < .005). Whereas, no difference was detected between group 1 and group 2 (p = .75). No difference was noted in CMT between the groups (p = .35). Axial length measurement was very similar among all three groups (p = .62). After adjusting for age and axial length SFCT was significantly thinner in group 3 than the other groups (p < .001), but no statistically significant difference was found between group 1 and group 2.Conclusions: Choroidal thickness did not vary between eyes with MacTel type 2 with SRNV and without SRNV. Choroid was significantly thicker in MacTel type 2 with SRNV and without SRNV than healthy eyes.