[1] Michigan State Univ, Coll Vet Med, Small Anim Clin Sci, E Lansing, MI 48824 USA
[2] UCL Inst Ophthalmol, London, England
[3] Univ Michigan, Dept Biol Chem, Dept Ophthalmol & Visual Sci, Ann Arbor, MI 48109 USA
[4] Biomed Res Ctr Ophthalmol Moorfields, Natl Inst Hlth Res, London, England