The contents of this article are informational only and are not intended to be a substitute for professional medical advice, diagnosis, or treatment recommendations. This editorial presents the views and experiences of the author and does not reflect the opinions or recommendations of the publisher of Ophthalmology 360.
By Joseph Colcombe, MD, and Yasha Modi, MD
Macular telangiectasia type 2 (MacTel) is a bilateral, neurodegenerative disease of the macula.1 In MacTel, Müller cells, glial cells that are responsible for supporting photoreceptors and retinal neurons and maintaining the blood-retina barrier, become dysfunctional. The Müller cells cannot perform their metabolic and structural functions, and hallmark cystic cavitation of retinal tissue and ellipsoid zone (EZ) loss occurs.1,2 As photoreceptor disease progresses, scotomata can occur and diminish visual function,3 which becomes more severe as EZ loss begins to involve the fovea.4
MacTel is a relatively rare condition but is likely underdiagnosed.5 We see patients at a tertiary academic practice and the largest public hospital in Manhattan, where it is common for a patient to be referred because their ophthalmologist discovered unusual retinal findings, which ultimately turn out to be MacTel. Many of these patients have mild or early disease and are asymptomatic, so the use of imaging is a necessity to reach the correct diagnosis.
Diagnosing MacTel
Optical coherence tomography (OCT) is the imaging mainstay for diagnosing and monitoring MacTel. The first changes in MacTel begin in a region temporal to the fovea; characteristic findings include cavitary loss of tissue, attenuation, disruption, and breaks in the EZ and external limiting membrane, as well as hyperreflective deposits in the retina.6 Perhaps the most recognizable change on OCT is the “internal limiting membrane (ILM) drape sign,” where the ILM is seen draping over a region of cystic tissue loss.1
OCT angiography (OCTA), now readily available in many clinics, is another valuable diagnostic tool. Vascular changes such as decreased vessel density and irregular, telangiectatic branches are seen initially in the deep capillary plexus before progression to the superficial capillary plexus. As is common in MacTel, these changes begin temporal to the fovea before progressing centrally. OCTA is also valuable for identifying early subretinal neovascularization, a potential complication of late-stage MacTel that can have devastating consequences for a patient’s vision.1
Fluorescein angiography was often employed for diagnosis prior to the widespread availability of OCT and can still provide utility in borderline patients, where prominent late-phase staining in the temporal macula occurs even in early cases. Some clinicians frequently utilize fundus autofluorescence, as patchy hyperautofluorescence can be seen even in the beginning stages of the disease due to loss of some masking macular pigments and unmasking of central lupofuscin.7 See FIGURE 1.
Managing Patients With MacTel
We owe a great deal of our knowledge of MacTel to Emily Chew, MD, a longtime researcher of the disease, and her study group at the National Eye Institute. A 2022 paper by her team used an algorithm to analyze data from a natural history study of MacTel patients to identify traits associated with disease severity. They identified that the extent and central location of EZ loss, the extent and central location of hyperreflective pigment deposits in the retina, and the presence of neovascularization best predict vision loss. Based on these findings, they created a 7-step scale of disease severity in MacTel.8 Further research into this model may prove fruitful for helping to identify patients who might benefit most from receiving treatment.
In our practice, we monitor patients for progressive cavitation and disorganization of the temporal retina as well as the development of breaks in the EZ and especially note as these changes progress toward the fovea.
Conclusion
Diagnosing MacTel, particularly in the early stages of disease, depends on a thorough understanding of the available imaging modalities, especially OCT and OCT-A. We encourage all ophthalmologists to become familiar with the diagnostic markers of MacTel.
Joseph Colcombe, MD, is an ophthalmology resident at NYU Langone Health. Dr. Colcombe reports no pertinent disclosures or affiliations.
Yasha Modi, MD, is an uveitis and vitreoretinal surgeon. He is Vice Chair of Ophthalmology at Manhattan, Eye, Ear, and Throat Hospital (MEETH), Northwell Health. Dr. Modi has the following disclosures where is serves as a consultant or has participated in an advisory board: 4DMT (AB), AbbVie (C), Alcon (C), ANI (C), Bausch + Lomb (C), DORC (C), Eyepoint (C), Genentech (C), Neurotech (AB), Regeneron (C), Topcon (C), and Zeiss (C).
References
- Kedarisetti KC, Narayanan R, Stewart MW, Reddy Gurram N, Khanani AM. Macular telangiectasia type 2: a comprehensive review. Clin Ophthalmol. 2022;16:3297-3309. doi:10.2147/OPTH.S373538
- Powner MB, Gillies MC, Zhu M, Vevis K, Hunyor AP, Fruttiger M. Loss of Müller’s cells and photoreceptors in macular telangiectasia type 2. Ophthalmology. 2013;120(11):2344-2352. doi:10.1016/j.ophtha.2013.04.023
- Heeren TFC, Kitka D, Florea D, et al. Longitudinal correlation of ellipsoid zone loss and functional loss in macular telangiectasia type 2. Retina. 2018;38(suppl 1):S20-S26. doi:10.1097/IAE.0000000000001715
- Peto T, Heeren TFC, Clemons TE, et al. Correlation of clinical and structural progression with visual acuity loss in macular telangiectasia type 2: MacTel Project Report no. 6-The MacTel Research Group. Retina. 2018;38(Suppl 1):S8-S13. doi:10.1097/IAE.0000000000001697
- Klein R, Blodi BA, Meuer SM, Myers CE, Chew EY, Klein BE. The prevalence of macular telangiectasia type 2 in the Beaver Dam eye study. Am J Ophthalmol. 2010;150(1):55-62. doi:10.1016/j.ajo.2010.02.013
- Tzaridis S, Friedlander M; Macular Telangiectasia Type 2-Phase 2 CNTF Research Group. Functional relevance of hyper-reflectivity in macular telangiectasia type 2. Invest Ophthalmol Vis Sci. 2021;62(3):6. doi:10.1167/iovs.62.3.6
- Pauleikhoff L, Heeren TFC, Gliem M, et al. Fundus autofluorescence imaging in macular telangiectasia type 2: MacTel Study Report Number 9. Am J Ophthalmol. 2021;228:27-34. doi:10.1016/j.ajo.2021.03.022
- Chew EY, Peto T, Clemons TE, et al. Macular telangiectasia type 2: a classification system using multimodal imaging MacTel Project Report number 10. Ophthalmol Sci. 2022;3(2):100261. doi:10.1016/j.xops.2022.100261
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