Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface
Section snippets
Patients and methods
Forty-eight eyes of 14 men and 34 women who underwent bilateral LASIK for myopia or myopia and astigmatism were evaluated. The patients ranged in age from 26 to 54 years (mean, 39.2 years). Eighty-three percent of these patients wore contact lenses (10% hard contact lenses, 90% soft daily and extended wear) for a mean duration of 19.1 years. This research was conducted by medically qualified personnel in strict accordance with the guidelines of the University of Miami School of Medicine
Irritation symptoms
Patients reported minimal complaints of eye irritation before LASIK (Table 1). Symptom severity scores were significantly increased compared with preoperative values at 1 week, 12 months, and 16 months postoperatively (P < 0.007 at all time points) (Table 1).
Aqueous tear production and clearance
Patients had mean Schirmer 1 test scores of 23.95 ± 10.05 mm preoperatively. There was a small, but nonsignificant, decrease in Schirmer test scores at 1 week; however, the Schirmer test score significantly decreased to 18 ± 10.42 mm (P <
Discussion
Our study indicates that LASIK results in decreased ocular sensitivity to touch that is accompanied by an early decrease in aqueous tear production, corneal punctate epitheliopathy and corneal surface irregularity, and a progressive decrease in tear fluorescein clearance.
The cornea is innervated by sensory nerve fibers from the ophthalmic division of the trigeminal nerve (Vth cranial nerve), whose cell bodies lie in the trigeminal ganglion, and by sympathetic nerves, whose cell bodies lie in
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