Effect of Prostaglandin Analogues With and Without Preservatives on Meibomian Glands in Glaucoma Patients

Study Methodology and Population

A total of 120 patients who visited the South Korean eye clinic of Chonnam National University Hospital between 2017 and 2018 were included in this retrospective study. Of these, 80 were newly diagnosed patients with open-angle glaucoma (OAG), and 40 were in the control group. OAG patients used PGA (latanoprost or tafluprost) with benzalkonium chloride preservative (PC; n = 42) or without it (PF; n = 38) as monotherapy for 12 months. Exclusion criteria were:

• previous eye surgery
• contact lens use
• recent eye inflammation or infection
• previous or current use of other eye drops including artificial tears
• systemic treatment affecting tear secretion
• eye surface abnormalities detected by slit-lamp examination

The inclusion criteria for the control group were:

• healthy patients without glaucoma, previous eye surgery, dry eye syndrome, or significant eye surface disease
• intraocular pressure (IOP) < 21 mmHg

All patients completed the OSDI (Ocular Surface Disease Index) questionnaire to evaluate subjective eye symptoms before treatment and after 12 months. They also underwent eye surface examinations including the BUT (break-up time) test to assess tear film stability, ocular surface staining (OSS), and the Schirmer test to quantitatively assess tear production. Meibomian gland evaluations included assessments of their morphology (dropout), function (expression and secretion quality), and eyelid margin abnormalities.

Results

No significant differences were observed between groups in terms of gender, average age, OSDI scores, eye surface parameters, and Meibomian gland status. Patients using PGAs initially had slightly higher IOP than the control group (p < 0.001), but no significant differences were observed between patients using PC-PGA and PF-PGA (13.67 ± 2.66 mmHg vs. 17.65 ± 2.76 mmHg; p = 0.682).

Worsening of Meibomian gland parameters was observed in both groups of patients using PGAs (PC and PF; p < 0.05) after 12 months of treatment. The most significant worsening of eye surface parameters (BUT and OSS), Meibomian gland status, and subjective perception of eye symptoms was evident in the PC-PGA group (p < 0.05). However, OSS was worsened compared to the control group even in the PF-PGA group. Schirmer test results remained unchanged across all three groups.

Conclusion and Discussion

After 12 months of using PGAs, damage to the eye surface and Meibomian glands was observed regardless of the presence of preservatives. This damage, contributed by both PGAs and preservatives, was less severe in patients using PF-PGA. The mechanism behind these changes remains unclear. Future studies are necessary to assess whether Meibomian gland obstruction progresses even after treatment cessation.

Before initiating PGA treatment, the morphology and function of the Meibomian glands should be carefully assessed. Eye drops without preservatives, which are less irritating, should be preferred, especially in patients with pre-existing eye surface conditions.

The study is limited by its retrospective single-center design and short follow-up period, preventing the long-term evaluation of PGA and preservative effects. The effects of benzalkonium chloride may be dose-dependent; however, its concentrations in latanoprost and tafluprost eye drops were different (0.02 vs. 0.001 %).

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Source: Ha J. Y., Sung M. S., Park S. W. Effects of preservative on the meibomian gland in glaucoma patients treated with prostaglandin analogues. Chonnam Med J 2019; 55 (3): 156–162, doi: 10.4068/cmj.2019.55.3.156.