Nomogram for Aspheric Q-Factor Optimized Excimer Laser Treatments for Myopia

David Kent

Fendalton Eye Clinic, Christchurch, New Zealand

Purpose
To develop the most accurate nomogram for optimizing outcomes with aspheric Q-Factor corrected excimer laser treatments on the Technolas Zyoptix platform.

Methods
Three-month results of femtosecond LASIK treatments in over 1500 eyes were collected in a database over a four-year period. The following pre-operative factors were considered as possible predictors of the three-month refractive outcome: subjective sphere, subjective cylinder, pachymetry, keratometry, Q-factor, age and optical zone. Best subset regression analysis was used to determine the significant factors and multiple linear regression used to derive a treatment nomogram.

Results
Statistically significant determinants of three-month mean spherical equivalent were pre-operative subjective sphere (P<0.001), patient age (P<0.001) and Q-factor (P=0.029). The derived best nomogram is to add the following correction factor to the subjective myopic refraction: -0.39 + (0.0066 * age) + (0.088 * subjective sphere) – (0.14 * Q-value).

Conclusions
With aspheric Q-factor derived excimer laser treatments the most optimal nomogram will decrease the myopic correction with increasing patient age, increase the myopic correction with more myopic sphere and increase the myopic correction with higher Q-values.