Contact Lens Case Reports

Preservative Toxicity While Using Scleral Lenses

BY PATRICK J. CAROLINE, FAAO, & MARK P. ANDRÉ, FAAO

In our July 2014 Case Reports column, we reported that studies at Pacific University had shown that minimal tear exchange takes place into or out of scleral lenses that clear the cornea and limbus. We hypothesized that shortly after the application of a scleral lens, it “sinks” into the boggy bulbar conjunctiva (43 microns within 30 minutes), creating a semi-closed solution reservoir beneath the lens. This means that whatever solution is placed into the bowl of the lens at application (usually preservative-free [PF] saline) remains beneath the lens, and in contact with the cornea, throughout the patient’s wear schedule.

Case History

Our patient is a 22-year-old male who has advanced keratoconus in both eyes. In March 2013, he reported an increasing intolerance to his right corneal contact lens that we were unable to resolve with lens changes and modifications. We subsequently fitted the patient with scleral lenses in both eyes. The patient was given oral and written instructions on the care and handling of the lenses, and he was instructed to use unit-dose inhalation saline in the bowl of the lens prior to lens application.

With the lenses, the patient was able to achieve 20/25 vision in both eyes and all day lens wear and comfort.

The patient remained symptom free until one month ago, when he began to experience a significant decrease in wearing comfort, diffuse conjunctival injection, and extreme photophobia.

The patient presented to the clinic with his scleral lenses on. His visual acuity was 20/40 in both eyes, and slit lamp examination showed diffuse conjunctival injection and an epithelial keratopathy indicative of a solution sensitivity that was equal in both eyes (Figure 1). The suspected corneal staining was confirmed with fluorescein, which showed a diffuse superficial punctate keratitis in both eyes (Figure 2).

Figure 1. White light image of the eyes upon initial presentation.

Figure 2. Fluorescein staining upon lens removal.

Diagnosis

By now, many of you have already diagnosed the problem, and you are correct. On further questioning, it was discovered that the patient had run out of his PF saline and had been using a GP conditioning solution to apply his lenses for the past three days. We instructed the patient on the need to use only PF solutions in the bowl of the lens prior to application, and the problem resolved in five days.

While this is an extreme case of preservative toxicity, we have seen less extreme reactions when patients forget to rinse the overnight storage solution from the posterior surface of the lens prior to filling the bowl with PF solution. Even that small amount of preservative left on the lens can cause ocular irritation in some patients. CLS

Patrick Caroline is an associate professor of optometry at Pacific University. He is also a consultant to Contamac. Mark André is an associate professor of optometry at Pacific University. He is also a consultant for CooperVision.