Biomaterial Database

Rigid lens tear pump efficiency: effects of overall diameter/base curve combinations. 1991

B A Fink, and L G Carney, and R M Hill

College of Optometry, Ohio State University, Columbus.

The effect of changes in rigid contact lens overall and optic zone diameters on tear pump efficiency were studied using a polarographic technique. Six overall diameters ranged from 7.6 to 10.6 mm in 0.6-mm steps, with the optic zone diameter always being 1.4 mm smaller. Base curve radii were made flatter as lens overall/optic zone diameters increased in order to maintain a constant tear layer thickness. All other parameters were held constant. Oxygen uptake rates were measured for the normal, open eye, as well as after 5 min of static (without blinking) and dynamic (with blinking once every 5 s) wear of each lens design. Under both static and dynamic conditions, oxygen uptake rates increased with increase in lens overall/optic zone diameter. The differences between the static and dynamic condition data served as an index of tear pump efficiency for each lens. These differences decreased with increase in lens overall/optic zone diameter.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011048	Polarography	An electrochemical technique for measuring the current that flows in solution as a function of an applied voltage. The observed polarographic wave, resulting from the electrochemical response, depends on the way voltage is applied (linear sweep or differential pulse) and the type of electrode used. Usually a mercury drop electrode is used.	DC Polarography,Pulse Polarography,Polarography, DC,Polarography, Pulse
D011474	Prosthesis Design	The plan and delineation of prostheses in general or a specific prosthesis.	Design, Prosthesis,Designs, Prosthesis,Prosthesis Designs
D001767	Blinking	Brief closing of the eyelids by involuntary normal periodic closing, as a protective measure, or by voluntary action.	Orbicularis Oculi Reflex,Reflex, Blink,Reflex, Corneal,Reflex, Orbicularis Oculi,Winking,Blink Reflexes,Corneal Reflexes,Orbicularis Oculi Reflexes,Blink Reflex,Reflexes, Blink,Reflexes, Orbicularis Oculi
D003261	Contact Lenses	Lenses designed to be worn on the front surface of the eyeball. (UMDNS, 1999)	Lenses, Contact,Contact Lens,Lens, Contact
D003315	Cornea	The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed)	Corneas
D005260	Female		Females
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000704	Analysis of Variance	A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.	ANOVA,Analysis, Variance,Variance Analysis,Analyses, Variance,Variance Analyses