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Clinton Norton Sims; A functional biomarker for subclinical age-related macular degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2017;58(8):2350.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies have demonstrated pupillary streaks of low luminosity are associated with varying degrees of AMD. Could similar pupillary streaks in eyes with normal fundi indicate subclinical AMD? If so, the incidence would be similar to the incidences of AMD of older persons in the Beaver Dam (BD) and Blue Mountain (BM) long term eye studies..
This was a retrospective clinical study of 77 patients with normal fundi and clear optical media seen in a general ophthalmology practice. Ages ranged from 50-89 (mean age 72.3), 56 % were female, 76.9% had a BMI >25 and 9% a familial AMD history. After a non-cycloplegic subjective refraction, a modified Copeland retinoscope (Fig. 1), calibrated for parallel light (0.00D vergence), was used to produce the initial pupillary streak. A secondary pupillary streak was produced using converging retinoscopic light (+1.00D vergence) to reduce the brightness of the initial pupillary reflex 1.8x. The luminosity of the pupillary streaks were graded using a photometric scale (Fig. 2) and averaged. The percentage of the subjects with low 0-2 photometric scores was calculated.
The incidence of low photometric scores was 42.7% and AMD incidences of older persons (age 75+) in the long term AMD studies were: 36.8% (1 year BD), 46.2% (10 year BD) and 56.6% (15 year BM).
The incidence of depressed pupillary reflexes seen with this technique are similar to the AMD incidences in the BD and BM studies. This technique appears to be a functional biomarker for subclinical AMD. The dense pigment particles of the retinal pigment epithelium (RPE), photoreceptors and choroid reflect the pupillary streak. Decreased density of the pigment particles in these tissues and destruction of rods and RPE decrease the luminosity of the pupillary streak. Other factors include the degradation of the pigment particles by the lysosomes and lipofuscin attached to melanosomes and the lower density of lipofuscin surrounding the pigment particles. Common risk factors are family history, obesity and smoking. Supplements of zeaxanthin, lutein, and mesozeaxanthin may be beneficial to those with subclinical AMD. In healthy eyes with bright pupillary reflexes, the melanin content of the RPE and choroid prevents the increasing lipofuscin formation associated with AMD.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Fig. 1 Calibrated retinoscope
Fig. 2 Photometric scale
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