July 2019
Volume 60, Issue 9
ARVO Annual Meeting Abstract  |   July 2019
Development of Outcome Measurements for Studies of Macular Telangiectasia (Mac Tel) Type 2
Author Affiliations & Notes
  • Emily Y Chew
    Epidemiology & Clinical Applications, National Eye Inst/NIH, Bethesda, Maryland, United States
  • Footnotes
    Commercial Relationships   Emily Chew, None
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 994. doi:
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      Emily Y Chew; Development of Outcome Measurements for Studies of Macular Telangiectasia (Mac Tel) Type 2. Invest. Ophthalmol. Vis. Sci. 2019;60(9):994.

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      © ARVO (1962-2015); The Authors (2016-present)

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Presentation Description : Macular telangiectasia (mac tel) type 2 is a relatively rare bilateral, slowly progressive, degenerative condition of the retina that is presents with fluorescein angiographic leakage of the retinal vessels, retinal opacification, crystalline deposits, cavities in the inner and outer retina on optical coherence tomography (OCT), and hyperpigmentation of the retina. This leads to marked decreases in visual function with blurred and distorted vision. These patients have profoundly reduced health-related quality of life measures compared with age--matched normal reference group. Initially, mac tel type 2 was considered a vascular disease due to observation of telangiectatic retinal vessels around the center of the macula but is now considered to be a primary neurodegenerative condition that also affects blood vessels and Müller cells Central vision loss (legal blindness) may occur in late stages, caused by retinal atrophy or neovascular complications.

There is no known effective therapy for this condition. We conducted phase 1 and 2 studies using ciliary neurotrophic factor (CNTF), a neurotrophic factor that can reduce photoreceptor cell loss in animal models of outer retinal degeneration. The Neurotech-501 (NT-501) encapsulated cell therapy implant is a novel, cell-based drug delivery system. Encapsulated in a semipermeable hollow fiber membrane, genetically modified human retinal pigment epithelium. The outcome measurement for these studies could not use visual acuity very gradually as these participants lose 1 letter per year. We borrowed lessons learned from the treatment trials of geographic atrophy associated with age-related macular degeneration (AMD). Again, vision loss is gradual in geographic atrophy. The FDA has approved the outcome of increase in area of geographic atrophy as measured by fundus autofluorescence (FAF). The two studies of Mac Tel type 2 used an outcome measurement that was derived from data from the Natural History Observational Study of Mac Tel type 2. The presence of the ellipsoid break (EZ) correlated with the functional changes and there was a slow progression of the area of the EZ break that would be evaluated via en face images obtained on OCT. Change in the area of the en face OCT imaging of the retina was used. The presentation will discuss the natural history and the findings from the clinical trials.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.


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