• Slowing Neurodegeneration in MacTel Type 2

    By Lynda Seminara
    Selected By: Stephen D. McLeod, MD

    Journal Highlights

    Ophthalmology, April 2019

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    Chew et al. tested the effects of cell-based delivery of a neuroprotective agent on the progression of macular telangiectasia (MacTel) type 2. They found that retinal degeneration pro­gressed more slowly in eyes that received the implanted device releasing ciliary neurotrophic factor (CNTF) into the vitreous cavity, and patients maintained monocular reading speed.

    This single-masked trial included 11 retina centers in the United States and Australia. The researchers enrolled 67 patients (99 eyes); study eyes were required to have disruption in the ellip­soid zone layer (evidence of photore­ceptor loss) ranging from 0.16 to 4.00 mm2 and best-corrected visual acuity of 20/50 or better.

    Participants were assigned randomly (1:1) to receive a sham operation or surgical implantation of an encapsu­lated system (NT-501, Neurotech) that provides sustained intravitreal delivery of human CNTF.

    The main outcome was the change from baseline to 24 months in the area of neurodegeneration, measured by spectral-domain optical coherence tomography in the area of ellipsoid zone disruption or photoreceptor loss. Secondary outcomes included between-group differences in visual function changes.

    Sixty-five of the 67 participants completed the trial; two died during the study period. The area of neurodegeneration progression was found to be 31% larger for sham-treated eyes. At 24 months, the difference in mean area of photoreceptor loss was 0.05 ± 0.03 mm2 (p = .04). Retinal sensitivity changes, as measured by microperime­try, correlated strongly with changes in the area of photoreceptor loss (r = 0.86; p < .0001). The mean retinal sensitivity loss in the sham group was 45% greater than for patients with active treatment (decrease of 15.81 ± 8.93 dB; p = .07). Although reading speed deteriorated in the sham group (–13.9 words/minute), it was maintained in the active-treat­ment arm (p = .02). Adverse effects occurred in 4% of each study group.

    Although the study results are promising, the authors encouraged more research to assess longer-term clinical outcomes and safety. They not­ed that their findings are not necessar­ily generalizable to all patients. Further study would be needed to understand the therapeutic effectiveness of the device in different patient populations.

    The original article can be found here.