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Long-term use of glaucoma drops affects conjunctival flora
Researchers found that indigenous flora may be affected by the long-term use of prostaglandin analog products.
They propose that the ocular surface flora can be influenced and changed relatively early after the administration of glaucoma eye drops.
The prospective study included 63 glaucoma patients who received continuous monotherapy with prostaglandin analogs for glaucoma for at least 1 year and 44 healthy volunteers.
Patients had received one of the following: Xalatan (latanoprost 0.005%, Pfizer) in 36 eyes (Xa group) or Travatan (travoprost 0.004%, Alcon) in 27 eyes (Tz group).
The positive culture rate in glaucoma patients was 90.5%, with a total of 79 isolates identified in 57 eyes.
The majority of isolates consisted of aerobic gram-positive cocci, such as Staphylococcus epidermidis, methicillin-resistant S. epidermidis (MRSE), other coagulase-negative staphylococci (CNS) and Streptococcus spp., aerobic gram-positive bacilli, gram-negative bacteria and other gram-positive bacteria and facultative anaerobes.
Methicillin-resistant Staphylococcus aureus nor fungi was detected.
The positive culture rate from the healthy control group was 84.1%, with a total of 59 isolates identified from 37 eyes consisting of S. epidermidis, including MRSE, other CNS, Corynebacterium spp. and Propionibacterium acnes.
The positive culture rates in the Xa and Tz groups were 88.9% and 92.6%, respectively.
S. epidermidis was the most common isolate detected in these two groups.
Researchers found that susceptibility of the indigenous flora to antimicrobial agents differed depending on the type of eye drops used.
The researchers propose that the use of Xa for longer than 1 year might be sufficient to cause changes in the antibiotic susceptibility of S. epidermidis.
They suggest that it may be important to periodically monitor the indigenous flora in postoperative glaucoma eyes treated with eye drops, not only in IOP reduction but also for other ocular diseases. – by Abigail Sutton
Disclosures: Ohtani reports no relevant financial disclosures.
Perspective
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It has been more than 15 years since prostaglandin analogs became our first-line glaucoma therapy. They seamlessly replaced their competition with increased efficacy, fewer systemic side effects and convenient dosing and subsequently improved patient compliance.
Through the years, we have seen our patients present with the typical prostaglandin analog (PGA) side effects: conjunctival injection, hypertrichosis and increased pigmentation of the iris and periorbital skin. Additionally, many of these patients also develop a more concerning side effect: prostaglandin-associated periorbitopathy (PAP). Patients with PAP have ptosis of the upper lid, deepening of the upper lid sulcus, involution of dermatochalasis, atrophy of the periorbital fat, mild enophthalmos, inferior scleral show, increased lid vessel prominence and tight eyelids.
Ohtani and colleagues have alerted us to another concern. PGA can alter the indigenous flora of the ocular surface. Most concerning, Xalatan was found to increase the incidence of MRSE. These findings, in addition to the eyelid and orbital changes from PAP, may increase the potential risk of bacterial infections.
Although the literature and my personal experience do not suggest a higher rate of infectious conjunctivitis with PGA use, patients with a history of ab-externo surgical therapy require additional consideration given their increased infection risk profile.