The Role of Macular Pigment Carotenoids in the Pathogenesis and Treatment of Macular Telangiectasia Type 2 (MacTel)
Condition: Idiopathic Juxtafoveal Telangiectasia
MeSH terms: Telangiectasis
Study type: Observational

Summary: 
      Macular telangiectasia type 2 ("MacTel Type 2") is an uncommon eye disorder that results in
      slow vision loss beginning in middle age. The macula is the central part of the retina, which
      lines the back of the eye like the film of a camera. The macula is responsible for central or
      reading vision. Telangiectasis refers to dilated, leaky vessels, for example varicose veins
      in the legs. One of the earliest manifestations of macular telangiectasia type 2 is an
      acquired reduction and/or redistribution of the macular pigment carotenoids at the foveal
      center. Currently, the biochemical mechanisms and clinical significance underlying these
      changes are not known, but it seems likely that better understanding of this phenomenon could
      lead to new interventions against MacTel.

      The objectives of this study are to image the maculas of MacTel subjects using two-wavelength
      autofluorescence imaging and resonance Raman imaging to target the 7-degree radius pigment
      ring characteristic of macular telangiectasia type 2 in order to gain further insight into
      the significance of this early clinical sign, and to evaluate whether supplementation with
      oral zeaxanthin can normalize macular pigment distribution in MacTel subjects
    

Detailed description: 
      One of the earliest manifestations of macular telangiectasia type 2 ("MacTel") is an acquired
      reduction and/or redistribution of the macular pigment carotenoids at the foveal center.
      Currently, the biochemical mechanisms and clinical significance underlying these changes are
      not known, but it seems likely that better understanding of this phenomenon could lead to new
      interventions against MacTel.

      Dr. Bernstein's laboratory at the Moran Eye Center of the University of Utah has focused for
      the past fifteen years on the role of the macular pigment carotenoids, lutein and zeaxanthin,
      in maintaining macular health. These xanthophyll carotenoids are derived exclusively from the
      diet, especially from green leafy vegetables and orange-yellow fruits and vegetables. They
      are thought to protect the macula from light-induced oxidative damage by virtue of their
      light-screening and antioxidant properties. Dietary supplement products, from infant formula
      to those aimed at seniors, primarily contain lutein; however the central macula (the fovea)
      actually has been shown to have higher concentrations of zeaxanthin.

      Dr. Bernstein's lab has identified and characterized the binding proteins responsible for the
      uptake and stabilization of lutein and zeaxanthin in the macula, developed new, noninvasive
      methods to quantify and image carotenoids in the retina and many other non-ocular tissues,
      and has participated in intervention trials of lutein and zeaxanthin against age-related
      macular degeneration. As a leading site for identification of MacTel families in North
      America as part of the "MacTel Project", Dr. Bernstein and other researchers at the
      University of Utah have unique expertise in the biochemistry and biophysics of the macular
      pigment carotenoids that may help to hasten progress toward effective diagnosis and
      intervention against MacTel in a highly collaborative manner.

      Macular Pigment Imaging:

      Dr. Bernstein has extensive experience with various methods to image and quantify macular
      pigment in the living human eye, especially using autofluorescence imaging (AFI) and
      resonance Raman imaging (RRI). Dr. Bernstein is also currently utilizing these methods to
      evaluate age-related macular degeneration (AMD) patients participating in the "AREDS2" study.

      The objectives of this study are two-fold:

        1. To image the maculas of MacTel subjects using two-wavelength autofluorescence imaging
           (AFI) and resonance Raman imaging (RRI) to target the 7-degree radius pigment ring
           characteristic of macular telangiectasia type 2 in order to gain further insight into
           the significance of this early clinical sign;

        2. To evaluate whether supplementation with oral zeaxanthin can normalize macular pigment
           distribution in MacTel subjects.

      This is an open-label pilot study that will enroll up to ten patients affected with macular
      telangiectasia type 2 and evaluate them every six months for two years. All participants will
      take 20 mg of zeaxanthin supplement per day for the duration of the study. Macular pigment
      distributions will be determined using two-wavelength autofluorescence imaging and resonance
      Raman imaging.
    

Intervention name(s): zeaxanthin; zeaxanthin
Intervention type(s): Drug; Drug
Intervention description(s): 10 mg of EyePromise 10 (zeaxanthin) supplement, taken twice a day; 10 mg of EyePromise 10 (zeaxanthin) supplement, taken once a day
Observational model: Other
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Up to ten subjects of either gender who have MacTel (as confirmed by the MacTel central
        study Reading Center) will be invited to participate. Only those who can conveniently
        travel to the University of Utah for study evaluations will be approached since the project
        does not have sufficient funding to reimburse for travel expenses. Participants must agree
        to discontinue use of any other supplements containing substantial amounts of carotenoids
        for one month prior to the baseline visit and for the duration of the study.
      
Keywords: MacTel; Macular telangiectasia type 2