International contact lens clinic (New York, N.Y.)最新文献

Most would agree that computerized videokeratoscopy is capable of providing a view of the cornea that is unmatched by any other method. However, which view should be used: tangential or sagittal? The answer is both. Each provides different information. It is clinically important to have a system that enables us to have both measurements to better understand the changes in corneal shape (tangential) as well as corneal power (sagittal) in pre- and post-refractive surgical procedures. This article attempts to provide a simplified explanation of the differences between the sagittal and tangential dioptric plot.

Many contact lens wearers do not perform sufficient surfactant cleaning to remove deposited protein from their lenses. In this study, the “passive” protein removal performance during soaking/disinfection of two multipurpose solutions was investigated. Both artificially deposited and patient-worn etafilcon hydrogel lenses (Surevue, Vistakon, FDA group 4) were examined. Whole lenses or lens quarters were soaked in ReNu MultiPlus (Bausch & Lomb) or Complete Comfort Plus (Allergan). After soaking for 2–24 hours, lenses were removed and solutions assayed for desorbed lysozyme by spectrophotometry. Both multipurpose solutions performed passive protein removal during soaking. Complete removed more than ReNu (means of 211.5 vs 125.3 μg/lens from patient-worn lenses, respectively, after 7 hours). Protein assay of lens pieces after soaking indicated low (<60 μg/lens) amounts of superficial protein remaining in both solution groups. The removal represents 10–50% of the total protein load on the lens and may have an impact on the overall clinical performance of these products.

Lens flexure and residual astigmatism were evaluated with rigid gas permeable (RGP) contact lenses made in low, medium, and high oxygen permeable (Dk) materials to determine if significant differences would be apparent as lens Dk was changed. Fourteen successful RGP contact lens wearers had their customary lens parameters, including lens thickness, held constant in duplicate pairs made in low (15), medium (60), and high (150) Dk materials. Flexure measured by keratometry over the lenses and residual astigmatism by sphero-cylindrical over-refraction were determined after a 1-week daily wearing period for each lens. No significant differences were found within or between lens materials when comparing magnitude of flexure and residual astigmatism by over-refraction. These results indicate that practitioners can expect lenses across the spectrum of Dk values, such as those evaluated in this study, to perform in a similar manner regarding lens flexure and residual astigmatism.

The effect of a 50:50 mixture of L-α-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate and 2-O-α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydro-xydecanoate (BEN22) on the rate of papillary hypertrophy was studied in 47 contact lens wearers for two periods of 8 weeks each. The care solutions were 0.00025% chlorhexidine acetate (CHX) with or without 0.005% BEN22. CHX and CHX + BEN22 were used simultaneously by each subjects but in different eyes. The grade of papillary hypertrophy increased in both the CHX and the CHX + BEN22 group during the first period but not during the second period. There were no differences between protein content of lenses or tear lactoferrin activity in the groups. In giant papillary conjunctivitis, tear lactoferrin levels were low, but papillary hypertrophy in its milder forms did not correlate with tear lactoferrin levels. BEN22 was well tolerated but did not diminish the rate of papillary hypertrophy.

The purpose of this study was to investigate the protein deposit cleaning ability of new ReNu® MultiPlus™ (ReNu®¹) and new COMPLETE® brand ComfortPLUS™ Multi-Purpose Solution (COMPLETE®²) on hydrophilic contact lenses. New never-worn hydrophilic contact lenses (SUREVUE®³ etafilcon A, 58%) were used. Contact lenses were incubated in artificial tear solution for in vitro soaking; human-worn lenses were collected for in vivo assay. The measurements were performed using a UV spectrophotometer. The cleaning efficacy of COMPLETE® on protein deposits was significantly better than that of ReNu®. In the in vitro experiment, COMPLETE® removed about two times the amount of deposits than ReNu® did. In an in vivo experiment, the difference was even more remarkable. The differing cleaning efficacies of the two solutions may be due to differences in their pH, buffers, or cleaning components. The difference was not due to soaking time, as each solution reached a peak point after which no additional protein deposits were removed.