While macular telangiectasia (MacTel) can cause central vision loss, a new study in Ophthalmology suggests severe vision loss in MacTel type 2 patients is uncommon and may be related to photoreceptor atrophy in most individuals.

The team of researchers also found asymmetry in the disease, with right eyes generally showing slightly worse vision and more advanced progression. Additionally, the study reported MacTel-related neurodegeneration did not spread beyond the affected area.

The cross-sectional multicenter investigation included retinal imaging and clinical data from participants in the Natural History Observation (and Registry) of MacTel study.

The researchers considered best-corrected visual acuity (BCVA) and its relation to age, changes in eyes with very late disease defined by a BCVA of 20/200 or less, average retinal thickness on OCT, and the dimensions of the MacTel affected areas.

Out of 4,449 eyes of 2,248 participants, BCVA was 20/50 or worse in 37.3% of subjects and 20/200 or worse in 3.8%. Additionally, 18.4% and 0.7% of all patients had bilateral BCVA of 20/50 or worse and 20/200 or worse, respectively.

Also of note: right eyes had more advanced morphological changes and worse BCVA (71 letters in the right eye vs. 74 letters in the left).

Although BCVA correlated with participants’ ages, the effect size was small, the researchers found. If neovascularization or a macular hole was present, it frequently occurred in both eyes (33% and 17%, respectively).

Eyes with advanced disease (BCVA of 20/200 or worse) showed the following characteristics:

• Atrophy of the foveal photoreceptor layer with or without associated subretinal fibrosis.
• An affected MacTel area limited to a horizontal diameter not exceeding the distance between the temporal optic disc margin and foveal center, and the vertical diameter not exceeding approximately 0.85 times this distance (with the exceptions of eyes with large active or inactive neovascular membranes).
• Reduced retinal thickness measures within the MacTel area.
• Less frequent retinal greying and more frequent hyper-pigmentations compared with eyes with better BCVA.