ABSTRACT
BACKGROUND: Most corneal damage induced by contact lenses is due to interference with corneal oxygenation. OBJECTIVE: To investigate the effect on the rabbit cornea of a rigid gas-permeable contact lens with a newly designed periphery. METHOD: We fitted New Zealand white rabbits (n = 12) with RGP contact lenses that were identical in all respects except for the design of the periphery. In each animal, one contact lens had an innovative periphery consisting of a microscopic diffractive relief lathed on the back surface; the other contact lens was of a conventional design. The lenses were worn continuously for 7 days. During this experimental period and for 1 additional week we assessed the corneal damage by daily testing lactic dehydrogenase activity in the tears. RESULTS: On the last day of the experimental week and the first 3 days of the healing period, mean tear LDH activity was significantly lower in the eyes with the new contact lens design than in eyes with the conventional lenses. CONCLUSIONS: The novel periphery design reduces corneal damage resulting from contact lens wear, as reflected by LDH levels in the tears. The new design probably facilitates the flow and exchange of tears under the contact lens, resulting in improved metabolism of the cornea. These findings may also prove applicable to soft contact lenses.
Subject(s)
Contact Lenses , Epithelium, Corneal/metabolism , L-Lactate Dehydrogenase/metabolism , Tears/metabolism , Analysis of Variance , Animals , Epithelium, Corneal/injuries , Equipment Design , RabbitsABSTRACT
PURPOSE: To evaluate the objective and subjective performance of the Holo-Or multifocal contact lens, a new rigid gas permeable (RGP) trifocal diffractive contact lens. METHODS: Eleven experienced and two non-experienced RGP contact lens wearers participated in the study. Eleven patients were presbyopic (age range: 40-57 years) and two were aphakic (ages: 12 and 14 years). Each patient was evaluated by comparing best spectacle correction to Holo-Or multifocal contact lens correction, using the following tests of visual function: visual acuity at 6 m, 80 cm, and 40 cm; contrast sensitivity at near and distance; and depth of focus. RESULTS: No significant differences were found between best spectacle correction and the Holo-Or contact lenses. When using the contact lenses, there was an improvement in depth of focus and a small reduction in contrast sensitivity compared with best spectacle correction. Overall satisfaction and comfort was good to excellent in ten of thirteen patients. CONCLUSIONS: Holo-Or trifocal diffractive contact lenses are a satisfactory means of optical correction for patients with presbyopia or accommodative problems.
Subject(s)
Aphakia/therapy , Contact Lenses , Presbyopia/therapy , Adult , Aphakia/physiopathology , Contrast Sensitivity/physiology , Depth Perception/physiology , Female , Humans , Male , Middle Aged , Presbyopia/physiopathology , Prospective Studies , Visual Acuity/physiologyABSTRACT
BACKGROUND AND OBJECTIVE: The authors tested whether coating tissue with sodium hyaluronate (Na-HA) reduced postoperative adhesions and accelerated the healing process in strabismus surgery. MATERIALS AND METHODS: The surgical technique was tested during recession and resection operations performed on 30 rabbits and was compared with the use of NaCl 0.9%. Clinical, biomicroscopic examinations were performed on postoperative days 1, 2, 7, and 30 and histopathologic examinations were performed on postoperative days 2, 7, and 30. RESULTS: Clinically, there were no statistically significant differences between the study group and the control group. Also, there were no statistically significant differences between the two groups for most of the histopathologic criteria; however, new vessel formation was smaller with Na-HA than without it. Statistical significance was defined as P < .05. CONCLUSION: The authors found no significant positive effect of Na-HA on postoperative healing in rabbits.
Subject(s)
Hyaluronic Acid/administration & dosage , Oculomotor Muscles/surgery , Strabismus/surgery , Animals , Female , Follow-Up Studies , Oculomotor Muscles/pathology , Postoperative Complications/pathology , Postoperative Complications/prevention & control , Rabbits , Strabismus/pathology , Tissue Adhesions/pathology , Tissue Adhesions/prevention & control , Wound Healing/drug effectsABSTRACT
The purpose of this study was to test the objective and subjective performance of the Holo-Or Rigid Gas Permeable (RGP) Multifocal Contact Lens (MFCL), a new trifocal diffractive contact lens. Eleven experienced and two nonexperienced rigid gas permeable contact lens wearers participated in the study. Eleven patients were presbyopic (age 40-57) and two were aphakic (age 12 and 14). All patients were tested both with their best correction for distance and near and trifocal diffractive contact lenses. The follow-up period was 3-8 months. Subjective opinion was also assessed. Statistical analysis was performed using Student's t-test. We did not find any significant difference in visual acuity, measured at 6 m, 80 cm, and 40 cm, between best correction and Holo-Or diffractive contact lenses. Depth of focus improved to a statistically significant extent when using trifocal contact lenses. A small reduction in contrast sensitivity was observed when the patients used multifocal contact lenses. Overall satisfaction and comfort was good to excellent in 10 out of 13 patients. Two additional patients who used a bifocal model of the same contact lens design showed similar results. Holo-Or Trifocal Diffractive Contact Lenses are a satisfactory means of optical correction for patients with presbyopia or accommodative problems.
