Oscar A Candia, MD
- PROFESSOR | Ophthalmology
- PROFESSOR | Pharmacological Sciences
Dr. Oscar Candia is Professor and Vice Chair of the Department of Ophthalmology and Professor of Physiology and Biophysics.
Dr. Candia has served on the following editorial boards:
Current Eye Research, 1981-1998
Investigative Ophthalmology and Visual Science, Associate Editor, 1982-1987
American Journal of Physiology: Cell Physiology, 1999-present
Experimental Biology and Medicine, 2001-present
BS, Colegio Nacional General Manuel Belgrano
MD, University of Buenos Aires
ARVO Gold Fellow
1988 and 1994
Research to Prevent Blindness Senior Scientific Investigator Award
Alcon Recognition Research Award
Dr. Oscar Candia's general interests involve the characterization of basic physiological phenomena in ocular epithelia that are related to membrane permeability, and ionic and fluid transport. During the past few years, studies focused on transport mechanisms in the rabbit and bovine ciliary epithelium, the rabbit crystalline lens and cornea, and rabbit and porcine conjunctivae. This work involved measurements of transepithelial electrical parameters and radiolabeled fluxes of ions and water; immunoblotting and immunohistochemical approaches to characterize various transporters, channels and membrane receptors; and RT-PCR, to identify receptor subtypes.
Studies on the ciliary body modeled the ionic transport properties of this two-cell-layered epithelium, which has a critical role in the production of the aqueous humor that circulates through the chambers of the anterior segment of the eye and maintains the intraocular pressure.
Recent lens experiments examined the distribution the Na-K-2Cl cotransporter within the lens and factors that regulate its activity. This symport is relatively inactive under physiological conditions in the freshly isolated intact lens, but can be activated by hypertonic conditions, as well as various factors used to maintain lens cells in culture. In the rabbit lens, a description of ionic currents that enter and leave the lens that may serve as the driving force for an internal fluid circulation was provided. Furthermore, using mathematical models developed in his laboratory, it was found that fluid moves out and into the lens in a reversible manner during accommodation. Studies on the conjunctival epithelium have begun a characterization of the likely neuronal regulation of transepithelial ion transport. It is well recognized that the conjunctiva is extensively innervated. The underlying rationale for such is a quest for elaborating the secretory functions of the epithelium under the premise that such efforts might have utility in ameliorating complications from dry-eye diseases. Because of its relatively large surface area, active chloride transport by the conjunctiva with accompanying fluid secretion may contribute to a significant fraction of tear production (normally provided in healthy individuals by the lacrimal gland).
In addition to the Cl secretory activity of the conjunctival epithelium, the tissue also manifests a Na absorptive process in the apical-to-basolateral direction that is mediated by electrogenic Na-linked co-carriers for glucose and amino acids. Thus, depending upon which system is dominant, conjunctival ionic transport could potentially be a driving force for either fluid secretion into, or absorption from, the tear film.
In most recent work, Dr. Candia in collaboration with Dr. Rosana Gerometta of Universidad Nacional del Nordeste, developed a corticosteroid-induced ocular hypertension model in cow and sheep.
Candia O, Shi XP, Alvarez LJ. Reduction in water permeability of the rabbit conjunctival epithelium by. Exp Eye Res 1998; 66(5): 615-624.
Alvarez LJ, Turner H, Zamudio AC, Candia O. Serotonin-elicited Inhibition of Cl- Secretion in the Rabbit Conjunctival Epithelium. Am J Physiol Cell Physiol 2001; 280: C581-C592.
To CV, Do CW, Zamudio AC, Candia O. Model of ionic transport for bovine ciliary epithelium: effects of acetazolamide. Am J Physiol Cell Physiol 2001; 280(6): C1521-C1530.
Turner H, Alvarez LJ, Candia O. Identification and Localization of Acid-Base Transporters in the Conjunctival Epithelium. Exp Eye Res 2001; 72: 519-531.
Candia O, Zamudio AC. Regional distribution of the Na+ and K+ currents around the crystalline lens of rabbit. Am J Physiol Cell Physiol 2002; 282: C252-C262.
Gerometta R, Podos S, Danias J, Candia OA. Steroid-Induced Ocular Hypertension in Normal Sheep. Invest Ophthalmol Vis Sci 2009 Feb; 50(2): 669-673.
Kong CW, Gerometta R, Alvarez LJ, Candia OA. Changes in rabbit and cow lens shape and volume upon imposition of anisotonic conditions. Exp Eye Res 2009 May; In Press.
Gerometta R, Zamudio AC, Escobar DP, Candia OA. Volume change of the ocular lens during accommodation. Am J Physiol Cell Physiol 2007 Aug; 293(2): C797-804.
Zamudio AC, Candia OA, Kong CW, Wu B, Gerometta R. Surface change of the mammalian lens during accommodation. Am J Physiol Cell Physiol 2008 Jun; 294(6): C1430.
Law CS, Candia OA, To CH. Inhibitions of chloride transport and gap junction reduce fluid flow across the whole porcine ciliary epithelium. Invest Ophthalmol Vis Sci 2009 Mar; 50(3): 1299-1306.