Effect of Preoperative Tear Film Hyperosmolarity on LASIK Testing and Outcomes
Purpose
To compare the clinical LASIK outcomes of eyes with preoperative normal versus high tear osmolarity.
Methods
Data from consecutive patients who underwent uncomplicated LASIK targeting emmetropia was retrospectively reviewed to record preoperative medical and ocular histories and medications, tear film osmolarity (osm), and biomicroscopy. The cohort was retrospectively subdivided into hyperosmolar (osm 308 or higher, n=11) and normal osmolarity (osm 307 or less, n=12) in order to statistically compare preoperative wavefront and topography, and postoperative refractive results between these two groups.
Results
Hyperosmolar (mean osm 319.1±9.6) eyes required significantly more dry eye treatment modalities both preoperatively (mean 2.5±1.3 versus 0.75±1.1, p=0.003) and postoperatively (mean 2.2±1.1 versus 0.9±1.1, p=0.02) than the normal osmolarity (mean osm 296.5±4.8) group. Preoperative wavefront spherical aberration (Z40, mean 0.16±0.10 versus 0.06±0.08, p=0.03) was also higher in the hyperosmolar group. There was no statistically significant difference in high contrast uncorrected or best corrected visual acuity between the two groups. The mean postoperative defocus equivalent was higher in the hyperosmolar (mean 0.52±0.42 versus 0.27±0.28, p=0.1) eyes.
Conclusion
Diagnosis and treatment of dry eye syndrome, especially in the setting of preoperative hyperosmolarity, is a key component in the management of LASIK patients in order to optimize the quality of preoperative testing and improve postoperative refractive outcomes.