Topical ocular anaesthetic abuse in a contact lens wearer: a case of microbial keratitis



We describe the abuse of a topical ocular anaesthetic in a contact lens wearer who developed microbial keratitis.

A 26-year-old woman presented with a two-day history of blurred vision and a red irritated right eye. She was found to be a daily contact lens wearer who frequently slept in her lenses. The contact lenses had been prescribed by an optometrist one month previously and were daily disposables made of polyvinyl alcohol and therefore were not recommended for extended wear. The lenses had not been purchased on the internet. She admitted to using proxymetacaine 0.5% drops on removal of the lenses due to daily discomfort.

The use of the topical anaesthetic had not been discussed with her optometrist. She had obtained the drops from her workplace where she worked as a veterinary nurse and had free access to medications. On presentation, she had an anaesthetic eye drops bottle, which appeared contaminated (Figures 1 and 2).

Figure 1.

Photograph showing the proxymetacaine bottle, which is clearly old and contaminated

Figure 2.

Photograph of the bottle top with multiple areas of brown contamination under the lid showing poor hygiene

On examination, her visual acuity was 6/6 bilaterally. Slitlamp examination showed a well demarcated 0.75 mm epithelial defect with an underlying infiltrate and stromal haze on the paracentral right cornea (Figure 3). She was started on cephazolin 5% and gentamicin 1%, which are most effective against the most common pathogens found in microbial keratitis in South Australia.1 A corneal scraping was performed and was negative for bacteria and polymorphs. Corneal scraping was also negative for Herpes simplex virus, Varicella-Zoster virus and chlamydia. The anaesthetic bottle swab did not grow any bacteria. This is likely due to the antimicrobial activity of the active agents and/or the preservatives present in topical anaesthetic preparations, which have been shown to decrease the isolation rates of bacteria from infected corneas.2 Fungal cultures were negative.

Figure 3.

An anterior segment photograph of the right cornea showing a well demarcated epithelial defect with an underlying infiltrate and stromal haze

She showed good recovery after four days and after one week she was started on Flarex qid, which was then reduced to bid for a further week and then ceased. Flarex was used to prevent corneal scarring, which commonly occurs due to tissue destruction as a result of bacterial enzymes and toxins, as well as host immune responses.3 She was advised to never use anaesthetic eye drops for removal of her contact lens and to not sleep in them. She has been referred to her optometrist for refitting and further instruction on contact lens hygiene and aftercare.

This case highlights the importance of good contact lens handling practices and the need for aftercare examination of cases, as well as solution and drop bottles. Non-compliance in contact lens wear, including lens care and hygiene as well as overnight wear and full-time daily wear, are known risk factors for microbial keratitis, which can lead to loss of vision.4 A recent study has also shown that non-compliant extended wear occurs more frequently in younger people and in daily disposable wearers.5 To help improve compliance, it is vital that patients are given explanations, which describe why instructions given for lens care are consistent with sustained comfortable and safe lens wear. This case also shows the importance of progressive monitoring of compliance especially in new contact lens patients.