Therapeutics

Pearls of Corneal Clarity

Tips staff can use from corneal expert Thomas John, MD.

Thomas John, MD, a leader in lamellar corneal surgery, is a clinical associate professor at Loyola University and a regular columnist for Ophthalmic Professional’s sister publication, Ophthalmology Management. Though written for physicians, Dr. John’s column, “Corneal Clarity,” also includes points of concern to staff of all levels. Here, we review some of those points. Dr. John’s column runs bimonthly in Ophthalmology Management.

On Recognizing Conjunctivochalasis

Conjunctivochalasis (a common ocular surface condition characterized by the presence of excess folds of the conjunctiva) can be a major player of ocular surface disease and it often involves both eyes. However, even though it is a relatively common condition, it often eludes the radar screen of the examining physician, and the patient remains symptomatic. Additionally, it may be mistaken for or coexist with dry eyes. In the latter case, symptoms may overlap from both the ocular surface conditions, so the proper diagnosis is important to determine the appropriate treatment.

Conjunctivochalasis can result in a spectrum of ocular symptoms, ranging from aggravation of a dry eye at the mild stage to disturbance of tear outflow at the moderate stage, and exposure problems at the severe stage.¹

Besides being more prevalent in the elderly, conjunctivochalasis is usually bilateral. Symptoms range from ocular irritation, dry eye, and epiphora, to eye pain, ulceration and subconjunctival hemorrhage. Eye pain can be more severe than in dry eye syndrome. Ocular irritation can result from an unstable tear film and delayed tear clearance. Biomicroscopy will reveal redundant, conjunctival folds, perhaps along the lower or upper eyelid margins or circumferentially. It usually involves the temporal conjunctiva along the lower lid margin.

Use of topical fluorescein dye along with localized digital pressure on the globe through the eyelid in an upward direction can further augment the clinical appearance of these conjunctival folds. Depending on the severity, the eye may have more than one conjunctival fold. These excess conjunctival folds can disrupt the tear film and cause dry eye symptoms. If they occlude the punctal opening, they can lead to compromised tear outflow and tearing. — Corneal Clarity September 2013

On Topical Drops and Ointments

Topical drug delivery is the most common mode of treating eye diseases. However, once a drop is placed on the ocular surface of the inferior cul-de-sac, the tear film, assisted by the blink reflex, dilutes it and often drains it quickly away from the targeted location, returning to the normal resident volume.

In this context, to facilitate passive passage via diffusion across the corneal barrier, drug concentration becomes important. Hence, augmented drug absorption needs can accelerate corneal penetration and prolong corneal contact time. Drops (solutions or suspension) are preferred over ointments, because the latter can blur the vision. Drops are convenient, relatively safe, effective and usually well tolerated by patients. — Corneal Clarity, February 2013

Understanding Ophthalmic Preservatives

An ophthalmic, multi-dose medication consists of the active drug, viscosity-increasing agents, buffers and stabilizers, carrier vehicles, preservatives and the drug delivery system. Preservatives are mandated with all multidose, topical ophthalmic medications.

Numerous studies have shown that ophthalmic medications in the absence of preservatives often get contaminated with bacteria within a week or two of b.i.d. usage.² Besides the antimicrobial activity in the container, preservatives can also prevent biodegradation or decomposition of the active medication and thus prolong its shelf-life. As we know, however, many preservatives have been linked to harmful effects. — Corneal Clarity August, 2012

References:

1. Meller D, Tseng SC. Conjunctivochalasis: literature review and possible pathophysiology. Surv Ophthalmol. 1998;43:225-232.

2. Schein, OD, Hibberd PL, Starck T, Baker AS, Kenyon KR: Microbial contamination of in-use ocular medications. Arch Ophthalmol. 1992; 10: 82-85.