In vivo monitoring of corneal changes in patients treated with and without preservative-containing glaucoma medications

Study Design and Objectives

The objective of this prospective blinded study was to evaluate the in vivo effects of 0.0015% preservative-free tafluprost treatment on the cornea. A total of 93 patients were included: 44 were newly prescribed the preservative-free medication, and 14 switched from another medication. The group treated with preservative-containing 0.003% bimatoprost or 0.004% travoprost included 35 patients.

At the beginning of the study and every 6 months for 3 years, the authors performed a complete eye examination, including in vivo confocal microscopy of the cornea. The following parameters were assessed: keratocyte activation, subbasal nerve fiber density, tortuosity of these fibers, number of beadlike structures, and endothelial cell density.

Findings

At the initial examination, clinical findings were similar in both groups, except for intraocular pressure, which was lower in the group that switched treatments. Confocal microscopy parameters showed different trends from the beginning.

• At the initial visit, keratocyte activation was similar across all three groups (p = 0.43), but in the following months, there was a statistically significant reduction in keratocyte activation among patients who newly started on preservative-free medication (p = 0.004).
• Subbasal nerve fiber density tended to increase slightly in patients who switched to preservative-free medication (p = 0.07), while it remained stable in the other two groups.
• Nerve fiber tortuosity remained unchanged across all three groups during the study.
• The number of beadlike structures significantly increased in patients who switched treatments (p = 0.027).
• Endothelial cell density varied initially across the three groups (p = 0.007). It tended to decrease in the groups treated with preservative-free medication (newly treated and those who switched) (p = 0.048 and 0.001, respectively), whereas it increased in patients treated with preservative-containing medications (p = 0.006).

Conclusion

This study was the first to demonstrate that preservative-free glaucoma medication does not significantly alter corneal structures after 36 months of topical therapy but rather improves changes induced by long-term preservative-containing therapy.

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Source: Rossi G. C. M., Scudeller L., Lumini C. et al. An in vivo confocal, prospective, masked, 36 months study on glaucoma patients medically treated with preservative-free or preserved monotherapy. Sci Rep 2019 Mar 12; 9 (1): 4282, doi: 10.1038/s41598-019-41038-y.