New Modified Equation of Contact Lens Method in Determining Post Myopic Laser Refractive Surgery Corneal Power
- Author:
Md Muziman Syah MM
;
Mutalib HA
- Publication Type:Original Article
- Keywords:
Equation, contact lens method, contact lens modified method, myopic laser refractive surgery,
- From:
The International Medical Journal Malaysia
2016;15(1):61-68
- CountryMalaysia
- Language:English
-
Abstract:
The purpose of this study was to derive a modified equation for contact lens method (CLM) in
calculating post myopic laser refractive surgery corneal power. Methods: A total of 93 subjects who
underwent myopic laser refractive surgery at IIUM Eye Specialist Clinic were recruited. The accuracy of
postoperative corneal power using the standard CLM and newly-derived contact lens modified method
(CLMmod) were compared to the standard comparison method ; the historical method (HM). The CLMmod
equation was derived by adjusting postoperative corneal power of CLM according to amount of refractive
change. Results: The mean postoperative corneal power using standard CLM was significantly higher than
HM (mean difference: -0.24 D, p < 0.001). Fifty seven percent (n = 53 eyes) of the standard CLM results were
within ±0.50 D of HM results. The difference between postoperative corneal power using standard CLM and
HM increased significantly with the amount of refractive change (r = 0.835; p < 0.001). The mean
postoperative corneal power of CLMmod showed that there was no statistical significant difference compared
to the HM results (mean difference: 0.00 D, p= 0.964). Eighty eight percent (n = 82 eyes) of the CLMmod
results were within ±0.50 D of HM results with improvement of 31% from the standard CLM results.
Conclusion: The CLMmod equation provides more accurate calculation in determining post myopic laser
refractive surgery corneal power. In near future, this modified equation can be used as an alternative
equation to calculate postoperative corneal power when the preoperative data is unavailable.
