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Jared P. McDonald, Alex Katz, Paul L. Kaufman, Mike Nork, Mary Ann Croft; Accommodation, Lens And Muscle Movement Is Dampened Following Laser Treatment Of The Ora Serrata Region/vitreous Zonule Insertion Zone. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1366.
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To compare accommodative amplitude and lens and ciliary muscle movement with and without laser treatment in the region of the ora serrata/vitreous zonule insertion zone.
One eye of each monkey received ~0.5 mm adjacent spots of diode laser treatment (LT) 270º circumferentially around the eye in the region of the ora serrata, using an endoscopic camera via a pars plana incision. Central electrical stimulation of the Edinger-Westphal (E-W) nucleus and peripheral pharmacological stimulation of the ciliary muscle (1.5 mg/kg i.v. pilocarpine (PILO), and 15 sec 40% carbachol corneal iontophoresis OU (CARB)) were used to induce maximum accommodative responses in 4 rhesus monkeys (aged 5-12 yrs). Ultrasound biomicroscopy and goniovideography images were collected to compare ciliary body configuration, lens, and zonular attachments in the unaccommodated and accommodated states and in the LT and non-LT eyes.
Following LT, accommodative amplitude, lens, and muscle accommodative movements were reduced in response to central electrical (4/4 monkeys, ~2 weeks after treatment) and peripheral pharmacological stimulation (3/4 monkeys, ~90 days after LT), compared to ipsilateral or contralateral control eyes. The amount of laser-induced reduction in accommodation induced by central electrical, CARB or PILO stimulation was 8.1 ± 1.3 (n=4, p=0.02), 4.2 ± 1.3 (n=3, p=0.08) and 0.6 ± 0.8 (n=3) diopters, respectively. There was evidence of accommodative supersensitivity to CARB and PILO stimulation in the LT eye compared to the contralateral control eye in the fourth rhesus monkey 106 days after LT. In the non-supersentive monkeys CARB induced 14.9 ± 2.2 (n=3, p=0.006) and 13.7 ± 1.9 (n=3, p=0.08) diopters more accommodation than that induced by electrical stimulation in the LT and control eyes respectively.
Transvitreal diode LT of the vireous zonule insertion zone near the ora serrata induced denervation of the ciliary muscle that could reduce accommodative muscle movement and thereby accommodative amplitude. In addition, the LT may have induced decreased accommodative mobility of the ciliary muscle posterior tendons and/or vitreous zonule insertion zone in the region of the ora serrata that could also reduce accommodative amplitude. This model may prove useful in determining the effect of chronically decreased ciliary muscle mobility, as occurs in presbyopia, on lens function.
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