Purpose: To investigate the effect of corneal thinning after laser in situ keratomileusis (LASIK) on the corneal penetration of topical eye medication. Setting: Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA. Methods: Laser in situ keratomileusis surgery was performed in 19 eyes of 10 patients enrolled in this prospective study. Measurements were made before surgery and 3 months postoperatively. After instillation of tropicamide 1%, the change in pupil size over time was measured with a Colvard pupillometer. Central corneal thickness (CCT) was measured with ultrasonic pachymetry before and 3 months after LASIK. The corneal epithelial condition was also examined by fluorescein dye staining. Results: The mean CCT decreased significantly from 564 μm ± 33 (SD) before LASIK surgery to 514 ± 48 μm 3 months postoperatively (P<.0001). Pupil diameter 10, 15, and 20 minutes after tropicamide 1% instillation was significantly larger 3 months after surgery than preoperatively (P =. 0083, P =. 0043, and P =. 0144, respectively). The mean time to reach a pupil diameter of 6.0 mm decreased significantly from 14.4 ± 4.3 minutes in preoperative eyes to 11.5 ± 2.3 minutes in postoperative eyes (P =. 0281). Mild punctate corneal epithelial staining (fewer than 5 spots) were observed in 4 eyes at the 3-month postoperative examination. Conclusions: Pupil dilation after tropicamide 1% instillation was significantly faster after LASIK surgery. Corneal thinning that resulted from LASIK enhanced corneal penetration of tropicamide 1%.
ASJC Scopus subject areas
- Sensory Systems