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.