Evaluation of a new system of lens parameter selection and comparison of traditional vs one-step lens care systems for aspheric high-Dk RGP contact lenses.
OBJECTIVE
We investigated the value of newly developed systems for parameter selection on the performance of high Dk rigid gas permeable (RGP) contact lenses with a spheric-aspheric design made of Boston Equa material in normal daily wear conditions. A comparison was also made between the safety and efficacy of a traditional care system vs a one-step chemical care system during the follow-up period of 1 year.


METHODS
A total of 66 patients were randomly assigned to traditional and newly developed systems for computing the back optical zone radius (BOZR) and the total diameter (TD) of the lenses. Evaluation parameters incorporated assessment of fit, visual acuity, wearing time, comfort, and lens condition.


RESULTS
The traditional method of computing the BOZR, using a method based on flat-K, predicted the BOZR successfully in 83% of the cases. Corneal topometry reached a lower, but not significantly different (P > 0.01) value of 75% correct prediction of BOZR. Analysis of the differences in eccentricity (E) values between quadrants per eye was a significant (P < 0.001) factor in fault predictions in the topometric system. A newly developed guide forTD selection performed, with 90% correct predictions, significantly (P < 0.01) better than a traditional method (72%) based on corneal diameter on supraversion. No significant differences (P > 0.05) were found in the capabilities of care systems (a traditional care system using a surfactant cleaner vs a one-step solution) to keep the lenses in proper condition and without deformation, over the 1 year follow-up period. The final success rate was 85%.


CONCLUSIONS
Although high Dk RGP contact lenses can be fit and used with a 85% success rate using advanced systems for determining the BOZR and TD, it remains necessary to evaluate the fit before dispensing high Dk RGP lenses in 15% of the cases. The one-step solution used in this study was a good starting point for lens care. If needed, surfactant cleaning in the traditional care system can be done without the risk of lens deformation.
de Brabander
J
J
Eye Research Institute Maastricht, Department of Ophthalmology, University of Maastricht, The Netherlands.
Kok
J H
JH
Nuijts
R M
RM
D000293:Adolescent; D000328:Adult; D001672:Biocompatible Materials / Q000592:standards; D018639:Contact Lens Solutions / Q000494:pharmacology; D003261:Contact Lenses / Q000592:standards; D003315:Cornea / Q000473:pathology; D006801:Humans; D011474:Prosthesis Design; D017755:Prosthesis Fitting; D012030:Refractive Errors / Q000473:pathology / Q000534:rehabilitation*; D012449:Safety; D013501:Surface-Active Agents / Q000494:pharmacology; D013997:Time Factors
D001672:Biocompatible Materials; D018639:Contact Lens Solutions; D013501:Surface-Active Agents