Background Macular telangiectasia type 2 (MacTel) is a neurodegenerative disease resulting in photoreceptor loss. Optical coherence tomography (OCT) reveals outer retina-associated hyperreflectivity (ORaH) as part of this process. The purpose of this study was to describe the incidence and phenotypical variation of ORaH.
Methods Different parameters of ORaH were analysed: OCT characteristics (Spectralis SD-OCT), correlation with vascular changes (OCT angiography; OCTA 3×3 mm Optovue) and correlation with hyperpigmentation (autofluorescence/fundus images). ORaH was also evaluated regarding the grade of severity of photoreceptor loss (Disease Severity Scale).
Results Of 220 eyes with MacTel type 2, 106 demonstrated ORaH. On OCT, the size, the extension into the inner retina and the contact with retinal pigment epithelium (RPE) of the ORaH were variable. On OCTA neovascularisation (NV) in the outer retina (OR) was present at the location of the ORaH in 97.6%. Increasing size of NV correlated with progressive photoreceptor loss. In 86.6% with NV, the flow signals were visible between the OR and the choriocapillaris. In 85.7%, the ORaH was associated with hyperpigmentation on autofluorescence and fundus colour images.
Conclusions The presence of ORaH is associated with increasing photoreceptor loss and disease severity. In these more advanced cases of the present study, a variable presentation of ORaH in respect to size and form was seen, but in most cases, ORaH was in contact to the RPE. Additionally, ORaH was associated with hyperpigmentation and OR NV on OCTA. These results are consistent with the concept of ORaH representing fibrovascular OR-NV with RPE proliferation after contact with the RPE.
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Contributors SM and DP were involved in the conception, data analysis and draft preparation; all other coauthors were involved in the conception and review of the draft.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests DP and AB are members of the international MacTel Consortium and have received travel support for the meeting of this Study Group from the LMRI.
Patient consent for publication Not required.
Ethics approval All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. In addition, a positive vote from the ethical committee of the University of Münster and the Westfalian Doctors Association was achieved and informed consent was obtained from all individual participants included in the study.
Data availability statement Data are available upon reasonable request. Data were taken from participants of the MacTel Study at the Department of Ophthalmology of the St. Franziskus Hospital in Muenster with confirmed diagnosis of MacTel type 2. Participants consented for data evaluation and data were deidentified.
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