Elsevier

Ophthalmology

Volume 108, Issue 7, July 2001, Pages 1230-1235
Ophthalmology

Effects of laser in situ keratomileusis on tear production, clearance, and the ocular surface

https://doi.org/10.1016/S0161-6420(01)00623-6Get rights and content

Abstract

Purpose

To evaluate components of the integrated ocular surface/lacrimal gland unit in a series of patients before and after undergoing bilateral laser in situ keratomileusis (LASIK).

Design

Prospective, noncomparative case series.

Participants

Forty-eight eyes of 14 men and 34 women (age range, 26–54; mean, 39.2 years) who underwent bilateral LASIK for myopia or myopic astigmatism.

Methods

LASIK was performed using a VISX Star Excimer Laser (Santa Clara, CA). Patients completed a questionnaire containing 11 questions that evaluated the character and severity of ocular irritation symptoms. Snellen visual acuity, tear fluorescein clearance, corneal fluorescein staining, aqueous tear production by the Schirmer 1 test, and corneal and conjunctival sensitivity were measured in each eye. Corneal surface regularity (SRI) was evaluated with the Tomey TMS-1 (Tomey, Cambridge, MA) topography instrument. Each randomly chosen eye was evaluated 1 to 2 days (T0) before LASIK and 7 days (T1), 1 (T2), 2 (T3), 6 (T4), 12 (T5), and 16 (T6) months postoperatively. A Wilcoxon test, two-tailed paired t test, Friedman test, or analysis of variance were used for statistical comparisons.

Main outcome measures

Components of the integrated ocular surface/lacrimal gland unit.

Results

Both corneal and conjunctival sensitivity were noted to be significantly decreased from preoperative levels at 1week, 1 month, 12 months, and 16 months postoperatively (P < 0.0002 at each time point). Symptom severity scores were significantly increased at 1 week, 12 months, and 16 months postoperatively (P < 0.007 at all time points). The mean Schirmer 1 test scores were 24 ± 14 mm preoperatively, and they decreased to 18 ± 14 mm by 1 month postoperatively (P < 0.001). Tear fluorescein clearance showed a linear increase postoperatively and was significantly greater than baseline (P < 0.001) at each time point. There was a significant increase in punctate corneal fluorescein staining at 1 week postoperatively (P < 0.0001), but staining returned to baseline by 12 months. There was a statistically significant increase in SRI 1 week postoperatively (P < 0.007) with return to baseline levels by 6 months.

Conclusions

Sensory denervation of the ocular surface after bilateral LASIK disrupts ocular surface tear dynamics and causes irritation symptoms. Patients undergoing LASIK should be informed of these risks.

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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