When Eye Drops Make the Red Eye Worse
Sunday, December 04, 2011
It happens at least once a week. A patient is referred to an ophthalmologist for management of an eye infection, which appeared to be improving with use of topical antibiotic eye drops only to reverse its course and become progressively worse.
What does the ophthalmologist recommend? Stop everything? At least for a few days, consider stopping all eye drops and, under close observation, determine whether it is, in fact, recurrence of the infection or, perhaps, secondary irritation caused by toxicity of the initial eye drops.
Eye drops are the foundation of treatment for the most common ocular disorders, including allergy, infection, dry eye, glaucoma and uveitis. Patients who undergo routine cataract surgery are prescribed eye drops for the pre-, intra- and postoperative periods. What makes it possible to use these eye drops through an entire course of treatment is the preservative contained in the bottle, in addition to the therapeutic agent and vehicle. The preservatives used in most multiuse topical ophthalmic products have been used for decades. Preservatives are essential for the safe and efficient treatment of most ocular disorders. However, an eye problem that initially improves and then worsens may be a red flag pointing to the potential for ocular toxicity caused by some preservatives.
Toxicity of a preservative refers to the chemical action of the preservative that leads to damage to or disturbance of function of any of the ocular surface structures. Virtually all premixed, multidose eye drops contain a preservative or preservative system to prevent microbial overgrowth. Most preservatives work either by dissolving lipid membranes — which leads to microbial cell wall lysis — or by interrupting oxidative reactions such that cell metabolism is disrupted. Examples of common preservatives include benzalkonium chloride (BAK), thimerosal, chlorobutanol, chlorhexidine and disodium EDTA. Some of the symptoms of ocular surface toxicity include ocular discomfort, scratchiness, tired eyes, burning, stinging, blurred vision and light sensitivity. Clinical signs on examination include superficial punctate keratitis (Figure 1), reduced tear volume, debris in the tear lake, conjunctival hyperemia and thickening of the lid margin. Advanced ocular disease associated with toxicity may include band keratopathy, filamentary keratitis and progressive symblepharon leading to pseudopemphigoid (Figure 2).
In response to the recognized potential for ocular surface disease related to preservatives, a number of new preservative formulations and systems have been developed. These include a “vanishing preservative” called purite, which degrades as soon as it is exposed to light (i.e. as soon as the drop leaves the bottle); sofZia, which is a preservative entity made from several components that are physiologically tolerated by the ocular surface, but, in combination, serve as an effective antimicrobial agent; and sodium perborate, which is converted to oxygen and water upon contact with the tear film. Finally, there are several preservative-free, unit-dose commercial products now available to treat dry-eye syndrome, as well as preservative-free formulations of prescribed medications for glaucoma. There is extensive research in progress to increase the availability of preservative-free ophthalmic products.
Mark D. Sherman, M.D., can be contacted at Pacific Eye Surgeons at (805) 545-8100. He is a specialist in cornea/external disease and uveitis and serves on the faculty at Loma Linda University School of Medicine.
When Eye Drops Make the Red Eye Worse
Photos © Mark Sherman, M.D.
MD News October/November 2011, Central Coast/Ventura County
Great Article by a Corneal Disease Specialist !
i have this problem of being allergic to pre cataract surgery meds and the dr has not yet found what meds to use, can you help?