Joseph P. Shovlin

Risk factors for corneal infiltrates with continuous wear of contact lenses

Purpose. To describe the factors associated with symptomatic corneal infiltrates in a postmarket surveillance study of continuous wear contact lenses. Methods. Patients intending to wear lotrafilcon A lenses continuously for 30 days and nights were registered in a 1-year study at 131 clinical sites. A self-administered questionnaire was used to gather demographic and other data at baseline. The severity of the incidence of corneal infiltrative events during the year-long study was graded by an independent adjudication committee. Results. Of 6245 lens wearers, 163 were reported to have symptomatic corneal infiltrative events (2.6%). In 159 wearers, the infiltrates were judged to be lens-related (2.5%). Age ≤25 years and >50 years was significantly associated with the development of corneal infiltrates (≤25 years OR = 1.75, 95% CI = 1.24–2.48 and >50 years OR = 2.04, 95% CI = 1.40–2.98). Ametropia of ≥5.00 D was significantly associated with corneal infiltrates (OR = 1.60, 95% CI = 1.08–2.37). Study participants who typically wore lenses for >21 consecutive days and nights were significantly less likely to have infiltrates than those who wore lenses for fewer consecutive days and nights (OR = 0.43, 95% CI = 0.24–0.75). Smoking concurrent with contact lens wear was weakly associated with corneal infiltrates (OR = 1.47, CI = 0.99–2.18). Conclusions. Patient age, degree of refractive error, and failure to achieve the intended wearing schedule were associated with development of symptomatic corneal infiltrative events.

Identification and susceptibility to multipurpose disinfectant solutions of bacteria isolated from contact lens storage cases of patients with corneal infiltrative events

Corneal infiltrative events (CIEs) are being reported with increasing frequency in lens wearers and may be related to specific multipurpose disinfecting solution (MPDS), contact lens type or bacterial bio-burden. Here, the efficacy of MPDSs against bacteria from contact lens storage cases (CLSC) of patients with CIEs was investigated. Eighteen CLSC from patients with CIEs were cultured. All reported using the same MPDS based on PQ-1+Aldox+nonanoyl-EDTA prior to experiencing CIEs. Bacteria were identified and tested for sensitivity to MPDS-1 and three other MPSDs. 16/18 CLSC (89%) contained bacterial counts of ≥10(4)-10(8)/mL. Achromobacter spp. was most frequently identified and was found in 11/18 cases (61%). This was followed by 4/18 (22%) Stenotrophomonas maltophilia, 3/18 (17%) Serratia marcescens, 3/18 (17%) Delftia spp., 2/18 (11%) Elizabethkingia spp., 2/18 (11%) Chryseobacterium indologenes and 1/18 Sphingobacterium spiritivorum. Acanthamoeba was not isolated. All of the Achromobacter strains were resistant to MPDS-1 with <1log10 kill up to 14 days exposure and the solution also showed reduced efficacy against the other isolates at the manufacturers recommended disinfection time of 6h. Two strains of S. maltophilia and Delftia spp. grew in the solution over 14 days. Factors responsible for causing adverse events such as CIEs in contact lens wearers remain unclear. However, the presence of significant bio-burden in the contact lens storage case and lens may initiate an immunological response resulting in CIEs either directly or through the release of endotoxins (e.g. lipopolysaccharides) from the bacterial outer cell membrane.

Hypersensitivity responses and contact lens wear

Hypersensitivity diseases that involve the eye are common reasons why patients present to eyecare practitioners. Common ocular hypersensitivity disorders include allergic conjunctivitis, giant or contact lens induced papillary conjunctivitis and atopic keratoconjunctivitis. The diagnosis and management of ocular hypersensitivity can present a challenge to eyecare practitioners and an understanding of the mechanisms that underlie the signs and symptoms of such conditions is necessary for their appropriate management. This article reviews the mechanisms by which the eye responds to antigenic challenges, the pathogenesis of ocular hypersensitivity responses, particularly in relation to contact lens wear, and illustrates possible management strategies.

5. What do we do now? Implications for the clinical practice

The primary objective of this supplement is to provide eye care practitioners (ECPs) with the latest research and experience on topics related to contact lens use and patient eye health. This section examines a variety of topics, including the challenges of keeping abreast of the scientific literature, recognizing data that are borne from well-designed studies, and keys to their implementation in clinical practice. Insights are also provided on how eye care is practiced in Asia, where regulations and patient perceptions result in care that is delivered much differently than in North America and Europe. The role of silicone hydrogel (SiHy) lenses in the clinical practice and how advances with this lens material may shape future lens prescribing are then reviewed. The final part examines the current thinking regarding corneal infiltrates, microbial keratitis (MK), and multipurpose solution (MPS)-related corneal staining, and how ECPs should approach these issues.