Corneal sensitivity and burning sensation. Comparing topical ketorolac and diclofenac
B. Seitz, K. Sorken, L. D. LaBree, J. J. Garbus and P. J. McDonnell
Doheny Eye Institute, University of Southern California School of Medicine, Los Angeles, USA.
OBJECTIVES: To compare the effect of topical 0.5% ketorolac tromethamine
and 0.1% diclofenac sodium on human corneal sensitivity and to assess the
intensity of burning sensation at specific intervals after drop
instillation. DESIGN AND SETTING: Double-masked parallel clinical study.
PATIENTS: Eleven women and 4 men (8 white, 4 Hispanic, 3 Asian), 22 to 60
years of age (mean [ +/- SD], 34 +/- 10 years). INTERVENTIONS: Repeated
instillation of either ketorolac and placebo or diclofenac and placebo at
5-minute intervals. MAIN OUTCOME MEASURES: Assessment of corneal
sensitivity before instillation, immediately after instillation, and after
termination of drop application; and subjective evaluation of burning
sensation by asking participants to rate burning on a scale ranging from 0
(none) to 3 (severe) after each drop application. RESULTS: Both diclofenac
(P < .01) and ketorolac (P < .01) decreased corneal sensitivity
significantly, while the placebo had no measurable effect. After
administration of additional drops over time, the effect of diclofenac and
ketorolac increased. After termination of the drug instillation, corneal
sensitivity returned to baseline significantly slower (P < .01) in
participants receiving diclofenac than in those receiving ketorolac.
Ketorolac (P = .01) and diclofenac (P < .05) were significantly more
effective in whites than in nonwhites. Mean burning sensation was mild, and
there was no statistically significant difference between the 2 drugs on
this measure (P = .12). CONCLUSIONS: The decrease in corneal sensitivity in
normal human corneas is more pronounced and longer lasting with diclofenac
than with ketorolac. Both drugs are well tolerated topically and may be
useful for pain reduction after refractive corneal surgery.
