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Effects of rigid gas permeable contact lens extended wear on rabbit cornea assessed by LDH activity, MDH activity, and albumin levels in tear fluid. 1993

M Imayasu, and T Moriyama, and J Ohashi, and H D Cavanagh
Department of Ophthalmology, University of Texas, Southwestern Medical Center, Dallas 75235-9057.

We used noninvasive biochemical techniques to study the effects on rabbit corneas of 7-day extended wear of rigid gas permeable (RGP) contact lenses of varying oxygen transmissibilities. Corneal effects were assessed through measurement of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) activities and albumin levels in tears. The RGP contact lenses used had Dk/Ltotal values ranging from 33 to 64 x 10(-9) (cm/sec) (mL O2/mL mmHg) and were of uniform 0.15 mm center thickness. Extended wear of high Dk (Dk/Ltotal = 34) and super high Dk (Dk/Ltotal = 56) lenses caused an increase in tear LDH activity from 1,190 U/L (before lens wear) to over 18,000 U/L during 7 days of continuous wear. These contact lenses also caused gradual increases in tear MDH activity from 431 U/L (before lens wear) to over 750 U/L after 7 days of continuous wear. Extended wear of the ultra high Dk lens (Dk/Ltotal = 64), however, caused no significant increase in LDH or MDH activity in tears. Tear albumin levels in all contact lens wearing eyes increased after 1 day of lens wear, then gradually recovered to normal values after 2 days of continuous wear. The changes in albumin levels did not correlate with Dk/Ltotal values of lenses worn.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D007770 L-Lactate Dehydrogenase A tetrameric enzyme that, along with the coenzyme NAD+, catalyzes the interconversion of LACTATE and PYRUVATE. In vertebrates, genes for three different subunits (LDH-A, LDH-B and LDH-C) exist. Lactate Dehydrogenase,Dehydrogenase, L-Lactate,Dehydrogenase, Lactate,L Lactate Dehydrogenase
D008291 Malate Dehydrogenase An enzyme that catalyzes the conversion of (S)-malate and NAD+ to oxaloacetate and NADH. EC 1.1.1.37. Malic Dehydrogenase,NAD-Malate Dehydrogenase,Dehydrogenase, Malate,Dehydrogenase, Malic,Dehydrogenase, NAD-Malate,NAD Malate Dehydrogenase
D010100 Oxygen An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration. Dioxygen,Oxygen-16,Oxygen 16
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D003262 Contact Lenses, Extended-Wear Hydrophilic contact lenses worn for an extended period or permanently. Contact Lens, Extended-Wear,Contact Lens, Extended Wear,Contact Lenses, Extended Wear,Extended-Wear Contact Lens,Extended-Wear Contact Lenses,Lens, Extended-Wear Contact,Lenses, Extended-Wear 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
D005136 Eye Proteins PROTEINS derived from TISSUES of the EYE. Proteins, Eye
D000221 Adaptation, Ocular The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed) Light Adaptation,Adaptation, Light,Adaptations, Light,Adaptations, Ocular,Light Adaptations,Ocular Adaptation,Ocular Adaptations
D000418 Albumins Water-soluble proteins found in egg whites, blood, lymph, and other tissues and fluids. They coagulate upon heating. Albumin
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia

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