Investigative ophthalmology & visual science
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Invest. Ophthalmol. Vis. Sci. · Aug 2013
Entrance pupil size predicts retinal illumination in darkly pigmented eyes, but not lightly pigmented eyes.
We determined the effect of entrance pupil size on retinal illumination. The influence of unilateral miosis on the magnitude of the pupil light reflex was studied to ascertain how a clinically significant anisocoria influences the relative afferent pupil defect (RAPD). ⋯ In darkly pigmented eyes, entrance pupil size significantly influenced the retinal illumination. However, retinal illumination of lightly pigmented eyes is relatively independent of entrance pupil size, presumably due to extrapupillary transmission of light through the iris and sclera. This has important implications in understanding the potential influence of anisocoria on the RAPD and also greater susceptibility of lightly pigmented eyes to light toxicity.
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Invest. Ophthalmol. Vis. Sci. · Aug 2013
Comparative StudyQuantitative assessment of the canine pupillary light reflex.
To develop instrumentation and methods for thorough quantitative assessment of the pupillary light reflex (PLR) in dogs under varying stimulus conditions. ⋯ A recording system and protocol have been developed to reliably quantify the canine PLR. The techniques and instrumentation will be useful for objective quantitative assessment of the PLR in dogs and other species in research applications and may be useful in clinical veterinary ophthalmology and neurology if PLR abnormalities detected with these procedures can be associated with specific diseases.
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Invest. Ophthalmol. Vis. Sci. · Jun 2013
MRI acquisition and analysis protocol for in vivo intraorbital optic nerve segmentation at 3T.
To present a new acquisition and analysis protocol for reliable and reproducible segmentation of the entire intraorbital optic nerve (ION) mean cross-sectional area by means of magnetic resonance imaging (MRI) at 3 tesla (T). ⋯ This study presents a new MRI acquisition and analysis protocol for reliable and reproducible in vivo measurement of the entire ION mean cross-sectional area as demonstrated in a pilot study of healthy subjects. The protocol presented here can be used in future studies of the ION in disease state.
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Invest. Ophthalmol. Vis. Sci. · Jun 2013
Analysis of saccades and peak velocity to symmetrical convergence stimuli: binocularly normal controls compared to convergence insufficiency patients.
To assess the potential peak velocity asymmetry between the left-eye and right-eye movement responses stimulated by symmetrical vergence steps in those with normal binocular vision and those with convergence insufficiency (CI) before and after vergence training. This study also evaluated whether vergence training influenced convergence peak velocity and the prevalence of saccades within the first second of the response. ⋯ Data suggest that vergence training improves the symmetry between the left-eye and right-eye movements, increases convergence peak velocity, and decreases the prevalence of saccades within the first second of the response, which facilitates binocular coordination in CI patients. Saccades may be a compensatory mechanism used by CI subjects when convergence peak velocity is reduced.
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Invest. Ophthalmol. Vis. Sci. · Jun 2013
Peroxisome proliferator-activated receptor-β/δ regulates angiogenic cell behaviors and oxygen-induced retinopathy.
To develop new therapies against ocular neovascularization (NV), we tested the effect of peroxisome proliferator-activated receptor-β/δ (PPAR-β/δ) agonism and antagonism on angiogenic behaviors and in human retinal microvascular endothelial cells (HRMEC) and on preretinal NV in rat oxygen-induced retinopathy (OIR). ⋯ PPAR-β/δ activation exacerbates, and its inhibition reduces, preretinal NV. PPAR-β/δ may regulate preretinal NV through a prodifferentiation/maturation mechanism that depends on Angptl4. Pharmacologic inhibition of PPAR-β/δ may provide a rational basis for therapeutic targeting of ocular NV.