M Jeandervin | PubMed Health

PubMed1998

Comparison of repeat videokeratography: repeatability and accuracy.

PURPOSE: We compared the repeatability and accuracy of four commercially available videokeratography instruments and a manual keratometer. METHODS: Ten optometry students and two university employees who had no history of rigid contact lens wear and no soft contact lens wear within 6 months of the study were measured. Two independent measurements were taken on the right eyes only using the Alcon EyeMap EH-290 topography system (both manual and automatic focus), the EyeSys System 2000 corneal topography system, the Humphrey Mastervue topography system, the Humphrey Atlas topography system, and a Marco manual keratometer. A three-factor repeated measures analysis of variance with all factors repeated was performed using SAS and BMDP statistical software. Separate analyses were conducted for paracentral and peripheral data. To test accuracy, measurements were taken with the Alcon EyeMap automatic focus system, the EyeSys System 2000, the Humphrey Atlas system, and the Humphrey Mastervue system using four calibration spheres. RESULTS: There were no statistically significant differences in the repeatability of the instruments. The EyeSys corneal topography system had the most narrow 95% limits of agreement around the mean difference. The two Humphrey instruments performed similarly to the EyeSys. Although the Alcon EyeMap EH-290 had the widest 95% limits of agreement around the mean difference, it showed better repeatability when the manual focus was used compared with the automatic focus. The instruments varied in their level of accuracy, but the highest percentage of data points within +/- 0.37 D of the known values of the calibration spheres was found with the Humphrey Atlas. CONCLUSIONS: Although there were no statistically significant differences in repeatability, the EyeSys System 2000 had the highest repeatability, which may have clinical relevance. The accuracy measured in this study varied tremendously; however, the Humphrey Atlas was found to be the most accurate of the instruments tested.

Cornea↗

PubMed1998

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Contact Lenses↗

PubMed1998

Effect of topical anesthetic use on initial patient satisfaction and overall success with rigid gas permeable contact lenses.

BACKGROUND: Rigid gas permeable (RGP) contact lenses have numerous benefits; however, RGP lens use is not increasing in the United States. An important factor for this trend has been initial comfort. Studies have demonstrated that how RGPs are presented to patients, in addition to lens design, can play an important role in the initial comfort process. Another important factor could be the use of a topical anesthetic during the fitting and dispensing visits. The purpose of this study was to use a multicenter format to determine if topical anesthetic use increased the likelihood of patient satisfaction and success. METHODS: A total of 80 subjects, with no previous rigid lens wear experience, was entered into this 1-month study, including 20 subjects from each of 4 institutions. Subjects were randomly divided into the following two groups: (A) anesthetic or (B) placebo, with the former group receiving one drop of a topical anesthetic before lens insertion at both the diagnostic fitting and dispensing visits, whereas the latter group received a placebo. Subjects completed a questionnaire on their perception of rigid lens wear both immediately before fitting and at the 1-month visit. After diagnostic fitting with rigid lenses, subjects completed an adaptation questionnaire after 15 min, 1 week, 2 weeks, and 1 month of lens wear. RESULTS: Seventy of the 80 subjects completed the study and, of the 10 subjects who discontinued, 8 were in the placebo group. In all categories evaluated, the anesthetic group experienced a more optimum adaptation experience at each visit vs. the placebo group. Specifically, overall comfort was rated significantly higher at both dispensing and 2 weeks. In addition, the anesthetic group exhibited significantly greater overall satisfaction with rigid lens wear at 2 and 4 weeks. Also, the anesthetic group perceived their adaptation, sensitivity, and adaptation time to be significantly better at the 1-month visit. There was no significant difference in corneal staining between these two groups at each visit, with the exception of a greater amount of staining in the central quadrant for the placebo group at the 1-month visit. CONCLUSIONS: The use of a topical anesthetic at the fitting and dispensing visits for first-time wearers of RGP lenses resulted in significantly fewer dropouts, improved initial comfort, an enhanced perception of the adaptation process, and greater overall satisfaction after 1 month of lens wear as compared to the use of a nonanesthetizing placebo at those visits. This result, in combination with both presenting RGP lenses in a nonthreatening manner and optimizing the lens design and fitting relationship, should result in a positive adaptation process and successful wear of RGP contact lenses.

Adaptation, Physiological↗