Efficacy and safety of fixed-combination bimatoprost/timolol ophthalmic solution.

Dear editor

We read, with interest, the article by Sun et al1 entitled “Patient satisfaction with fixed-combination bimatoprost/timolol ophthalmic solution: a survey study in patients with glaucoma in China”. This observational multicenter study with excellent design was undoubtedly well conducted, and the authors successfully demonstrated that fixed-combination bimatoprost/timolol ophthalmic solution can provide the glaucoma patients with improved satisfaction.1

However, we would like to point out that the measurement of intraocular pressure (IOP) would have been necessary for better evaluation of IOP lowering the efficacy of the regimen. Considering that normal-tension glaucoma is more prevalent than high-tension glaucoma in Asian patients,2 subjective assessment of IOP control could sometimes be inaccurate. IOP measurement in individual patients might be difficult due to this study including a large population residing in multiple areas. In this situation, review of medical records or survey with the participating physicians could be helpful.

Moreover, for more precise evaluation of tolerance and comfort, assessment of subjective symptom indices, such as ocular surface disease index and visual analog scale, would be beneficial.3 If possible, investigation of ocular surface signs using indices including tear film break-up time, Schirmer test and fluorescein stain score would also be helpful, considering that ocular surface disease is associated with increased severity of glaucoma and higher exposure to benzalkonium chloride.4

In addition, follow-up period of 1–3 months could be relatively short for the development of side effects. Therefore, we believe further studies with long-term follow-up including more precise parameters would be helpful for elucidation of efficacy and safety of fixed-combination bimatoprost/timolol ophthalmic solution.