Contrast Sensitivity and Eye Drops

Purpose: To evaluate the influence of commonly used eye drops on contrast sensitivity (CS). Design: Prospective study. Participants: One hundred twenty volunteers were enrolled. Methods: The CS of ophthalmologically healthy individuals was evaluated at baseline examination before the instillation, 20 and 40 minutes after the instillation of diclofenac sodium and commonly used anti-glaucoma eye drops (latanoprost, brimonidine tartrate, combination of dorzolamide hydrochloride and timolol maleate). CS was assessed at 7 spatial frequencies varying from 1.5 c/d to 20 c/d by the use of Mentor B-VAT II-SG video acuity tester. Results: Diclofenac sodium induced a mild, however statistically significant decrease on the CS in 4 out of 30 subjects 20 minutes after instillation at the spatial frequency of 1.5 c/d and 3 c/d (p < 0.05 for both frequencies). Latanoprost induced a decrease in CS in 1 out of 30 subjects and combination of dorzolamide hydrochloride and timolol maleate in 2 out of 30 at low spatial frequencies (1.5 c/d and 3 c/d) 20 minutes after the instillation and this decrease was not statistically significant for any of these drugs (p > 0.05). Brimonidine tartrate decreased CS in 4 out of 30 subjects 20 minutes after the instillation at a high spatial frequency (20 c/d) yet this decrease was marginally statistically significant (p = 0.057). CS returned to baseline scores 40 minutes after the instillation for all drugs. Conclusions: Diclofenac sodium eye drops had a mild temporal effect on the low spatial frequencies of 1.5 c/d and 3 c/d in some individuals. Latanoprost and dorzolamide/timolol had a non-statistically significant effect on the same spatial frequencies. Brimonidine eye drops had a temporal effect on the high spatial frequency of 20 c/d with marginal statistical significance. The CS scores returned to normal, in all cases, within the next 40 minutes after the instillation. Ophthalmologists should be aware of the fact that some eye drops may have an influence on CS.