Effect of Preserved and Preservative‑Free Timolol Eye Drops on Tear Film Stability in Healthy Africans

Abstract

Preserved versus nonpreserved formulations for ophthalmic use have been well described in the literature although not specifically in the African population where beta blockers are frequently used as the first‑line therapy due to economic and availability issues. This study sought to determine the effect of preserved and preservative‑free Timolol eye drops on tear film stability in healthy black Africans. Materials and Methods: Sixty healthy nondry eye subjects aged 19–25 years were randomly assigned into four groups (n = 15) and differently treated with eye drops of phosphate buffered saline (PBS), preservative‑free timolol (PFT), benzalkonium chloride (BAK) only, and BAK‑preserved timolol (BPT). Noninvasive tear break‑up time (NITBUT) was measured using the keratometer at baseline and 30, 60, and 90 min after drop application. Results: No significant decline in NITBUT was observed following treatment with PFT and PBS. However, BAK treatment showed a positive time‑dependent significant decline in NITBUT (P < 0.001) while a significant decline in the BPT‑treated group was only found at 90 min (−3.52 s; P < 0.001). In comparison to the PFT‑treated group, treatment with BAK and BPT showed significantly lower NITBUT (P < 0.001). Conclusion: BPT is associated with a significant decline in tear film stability in black Africans. This finding has implications in the management of glaucoma in patients with high‑risk of dry eyes in this population.