Pathogenesis and treatment of "sterile" midperipheral corneal infiltrates associated with soft contact lens use

Wessely corneal ring phenomenon: An unsolved pathophysiological dilemma

The cornea is a densely innervated, avascular tissue showing exceptional inflammatory and immune responses. The cornea is a site of lymphangiogenic and angiogenic privilege devoid of blood and lymphatic vessels that limits the entry of inflammatory cells from the adjacent and highly immunoreactive conjunctiva. Immunological and anatomical differences between the central and peripheral cornea are also necessary to sustain passive immune privilege. The lower density of antigen-presenting cells in the central cornea and the 5:1 peripheral-to-central corneal ratio of C1 are 2 main features conferring passive immune privilege. C1 activates the complement system by antigen-antibody complexes more effectively in the peripheral cornea and, thus, protects the central corneas' transparency from immune-driven and inflammatory reactions. Wessely rings, also known as corneal immune rings, are non-infectious ring-shaped stromal infiltrates usually formed in the peripheral cornea. They result from a hypersensitivity reaction to foreign antigens, including those of microorganism origin. Thus, they are thought to be composed of inflammatory cells and antigen-antibody complexes. Corneal immune rings have been associated with various infectious and non-infectious causes, including foreign bodies, contact lens wear, refractive procedures, and drugs. We describe the anatomical and immunologic basis underlying Wessely ring formation, its causes, clinical presentation, and management.

Current understanding and therapeutic management of contact lens associated sterile corneal infiltrates and microbial keratitis

Contact lenses are widely prescribed in clinical practice with multiple applications and advantages. However, contact lenses can be associated with various complications which range from innocuous to severe. Clinicians thus not only need to possess the ability to prescribe the most appropriate contact lenses for each individual patient but also be able to recognise and manage any associated complications. This review examines the existing literature on the management of corneal infiltrative events associated with soft contact lenses, including microbial keratitis, particularly in the context of practising in Australia. The definitions and diagnosis of corneal infiltrative events, as well as the current understanding of their aetiologies, will be explored. The various aspects of a successful management will be discussed, including the applications of therapeutic agents such as antimicrobial and anti-inflammatory agents, the role of microbiological investigations, and strategies to improve long-term prognosis. The currently available evidence supporting management options will be presented, highlighting the relative abundance of high-level evidence on management protocols, antimicrobial selection and treatment duration for microbial keratitis; and the relative paucity of studies and trials for sterile corneal infiltrative events, despite this condition being much more commonly encountered in clinical practice.

Therapeutic Contact Lenses in the Treatment of Corneal and Ocular Surface Diseases-A Review

Therapeutic contact lenses (TCLs) are often used in the management of a wide variety of corneal and ocular surface diseases (OSDs). Indications of TCL include pain relief, enhancing corneal healing, corneal sealing, corneal protection, and drug delivery. For painful corneal diseases such as bullous keratopathy, epidermolysis bullosa, and epithelial abrasions/erosions, bandage contact lenses (BCLs) provide symptomatic relief. Postoperatively in photorefractive keratectomy or laser epithelial keratomileusis, BCLs also alleviate pain. In severe OSDs such as severe dry eye, Stevens-Johnson syndrome/toxic epidermal necrolysis, gas-permeable scleral contact lenses are often used to enhance corneal healing. BCLs are used post-keratoplasty, post-trabeculectomy, and post-amniotic membrane transplantation to enhance healing. BCLs, with or without glue adhesives, are used to seal small corneal perforations and sometimes also used as bridging treatment before penetrating keratoplasty in larger corneal perforations. In patients with eyelid conditions such as trichiasis, ptosis, and tarsal scarring, BCLs are also effective in forming a mechanical barrier to protect the cornea. A relatively new use for TCLs is in ocular drug delivery where TCLs are used to maintain therapeutic concentrations of medication on the ocular surface. Contraindications of the use of TCLs include infective keratitis, corneal anesthesia, and significant exposure keratopathy with inadequate eyelid position or movement. Complications of TCL include infective keratitis, corneal hypoxia and associated complications, corneal allergies and inflammation, and poor lens fit. Overall, TCLs are effective in the treatment of corneal and OSDs but contraindications and complications must be considered.

The diagnosis and management of contact lens-related microbial keratitis

Contact lens-associated microbial keratitis poses a diagnostic dilemma for optometrists on two fronts. The distinction between sterile inflammation and microbial infection is often blurred. In addition, there is a requirement with nearly 50 per cent of the Australian and New Zealand optometric profession being therapeutically endorsed, to distinguish between cases of infection that can be managed in the community verses those that require escalation to public hospitals that have access to laboratory diagnostic tools and advanced imaging techniques, such as in vivo confocal microscopy. Pattern recognition and incorporation of knowledge of aetiology and risk factors assists optometrists to decide on optimal management strategies. Skilled optometrists will utilise emerging diagnostic and therapeutic technologies to ensure safe management strategies and better outcomes for these cases.

Sterile corneal infiltrates after corneal collagen cross-linking: evaluation of risk factors

PURPOSE

To evaluate possible risk factors leading to sterile corneal infiltrates following corneal collagen cross-linking (CXL).

METHODS

A total of 588 eyes of 459 patients treated with Epi-off (n = 461) or Epi-on (n = 127) CXL were retrospectively evaluated. Risk factors, including preoperative blepharitis and vernal conjunctivitis, the postoperative use of topical non-steroidal anti-inflammatory drugs (NSAIDs), as well as Kmax and pachymetry measurements, were assessed. In vivo confocal microscopy (IVCM) and anterior segment optical coherence tomography (AS-OCT) analyses were performed in patients with sterile infiltrates.

RESULTS

Sterile infiltrates developed in 19 cases (3.2%). No patients in the Epi-on group developed sterile infiltrates. The evaluation of acceleration of the CXL procedure as a risk factor revealed no specific difference in the incidence of infiltrates among four different Epi-off groups (3 mW/cm² -30 min, 9 mW/cm² -10 min, 18 mW/cm² -5 min, 30 mW/cm² -4 min procedures; p > 0.05, all). Blepharitis, vernal conjunctivitis, Kmax and pachymetry were not identified as risk factors (p > 0.05). Postoperative use of NSAIDs was a significant contributor (p = 0.007), and it increased the chance of sterile infiltrates 4.09 times (95% CI, 1.463-11.428). In vivo confocal microscopy (IVCM) showed non-specific inflammation with dendritic cells at the epithelium and at Bowman's layer. In AS-OCT, a hyper-reflective band at the level of the anterior stroma to a depth of 100-140 μm was observed.

CONCLUSION

The evaluation of the risk factors such as blepharitis, the use of NSAIDs, vernal conjunctivitis, the duration of CXL procedure and amount of light intensity showed that epithelial damage is possibly the common pathway in the pathogenesis, as no sterile infiltrates in Epi-on CXL occurred, and the postoperative use of NSAIDs increased the risk of developing sterile infiltrates about four times.

Characterizing Contact Lens-Related Corneal Infiltrates: A Pilot Study

Purpose:

To document the time course and resolution of contact lens–related corneal infiltrative events (CIEs) comparing slit-lamp images with anterior segment ocular coherence tomography (AS-OCT) images.

Methods:

Six silicone hydrogel (SiHy) soft contact lens (SCL) wearers presenting with newly diagnosed symptomatic CIEs were monitored with slit-lamp images, detailed drawings, and AS-OCT until the resolution of the CIE. A final follow-up visit was completed 4 weeks after CIE resolution to determine whether scar formation was present. Positive controls were 2 SiHy SCL wearers with established (inactive) corneal scars, and negative controls were 2 SiHy SCL wearers with clear corneas. High- and low-contrast logMAR visual acuities were measured, and subjective symptom questionnaires were completed at all visits.

Results:

Clinical signs, vision, and symptoms improved in tandem with the resolution of the CIEs as measured by imaging methods. Calibrated measures of infiltrate width from a slit-lamp biomicroscope appear to be similar to calibrated images from AS-OCT.

Conclusions:

Although further studies are needed to develop standardized procedures, AS-OCT can be a useful tool to characterize the development, progression, and resolution of corneal infiltrates as an objective measure of resolution and scar formation.

Peripheral sterile corneal infiltrate in two brothers after photorefractive keratectomy

This is a report of two brothers who underwent bilateral photorefractive keratectomy and developed bilateral peripheral corneal infiltrate on the third day following surgery. The patients were treated with antibiotics and low concentration steroid until negative culture was reported 48 h later, when intensive topical steroid was started. The infiltrate resolved by day 10 with residual subepithelial haze that was apparent 8 months after surgery. Sterile infiltrate has been reported as complication of photorefractive keratectomy and can be managed successfully with excellent outcome. The fact that it happened in two brothers may raise the possibility of genetic predisposition.

Efficacy and safety of bromfenac for the treatment of corneal ulcer pain

PURPOSE

To evaluate the efficacy and safety of bromfenac ophthalmic solution 0.09% (Xibrom™, ISTA Pharmaceuticals Inc., Irvine, CA, USA) for treating pain associated with corneal ulcers.

METHODS

Twenty-five eyes of 24 patients with corneal infiltrates (bacterial or fungal) were treated with appropriate anti-infective agents along with bromfenac twice daily for up to 102 days to treat the pain caused by the infection. Follow-up visits were frequent in the first 2 weeks upon initiation of treatment, then at least weekly until infections were resolved. The best corrected visual acuity, location, size, and density of corneal infiltrates, the size and presence of a corneal epithelial defect, subjective eye pain (scale of 0-4) and time to pain resolution, the ability to conduct daily activities, and adverse events were recorded at each follow-up visit. The results of these treated patients were compared with those of 10 control eyes with corneal infiltrates (bacterial or fungal) where appropriate anti-infectives were used without adjunct medications.

RESULTS

Fifty-two percent of bromfenac-treated patients reported no pain by day 3, compared with 0% of untreated controls (P=0.023). Most of the treated patients' epithelium healed by day 20 (68%) compared with only 10% of controls (P=0.040). Most bromfenac-treated patients (71%) returned to normal activities within 2 days of starting treatment with bromfenac, compared with 0% of controls (P=0.018). No adverse events were recorded.

CONCLUSION

Bromfenac was effective in treating pain associated with infectious keratitis and did not delay corneal epithelialization nor cause any corneal adverse events in this group of 25 eyes.

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 < or =25 years and >50 years was significantly associated with the development of corneal infiltrates (< or =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 > or =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.

Amniotic Membrane Transplantation in Severe Bacterial Keratitis

PURPOSE

To determine whether a combination of early amniotic membrane transplantation (AMT) and early topical corticosteroid treatment could be a safe adjuvant therapy during antibacterial treatment in severe bacterial keratitis (BK) for relieving pain, avoiding iatrogenic epithelial toxicity, and allowing earlier use of topical steroids.

METHODS

In a prospective noncomparative case series, 12 patients with severe microscopically-proven BK were treated with immediate maximal topical antibiotics followed by AMT at 48 hours (single-layer epithelial side-down or multilayer epithelial side-up), plus topical steroid treatment at 72 hours. Pain relief (NRS-11 numeric rating pain scale) and the corneal epithelium healing were measured.

RESULTS

The follow-up rate was 7.5 person-months, with AMT performed once in 2 patients and twice in 10 patients with BK caused by Pseudomonas aeruginosa (5), Klebsiella pneumoniae (1), Moraxella cattharalis (1), Staphylococcus aureus (1), Staphylococcus epidermidis (2), or Streptococcus pneumoniae (1). A significant decrease in the pain score was noted from the admission day (median, 8; range, 7-10) to shortly after AMT (at day 3: median, 2; range, 1-3). Epithelial healing was achieved between 8 and 45 days (mean, 25.5 +/- 9.7 days). Neither perforation nor neovascularization was observed.

CONCLUSIONS

Early AMT combined with topical corticosteroid in severe BK provides immediate pain relief and allows epithelial healing.

Prolonging contact lens wear and making contact lens wear safer

PURPOSE

To summarize the present status of safety and efficacy of contact lens wear.

DESIGN

Literature review.

METHODS

Ovid Medline searches were performed on records from 1966 through 2005 using keywords: keratitis, contact lens complications, extended-wear contact lenses, and silicone-hydrogel contact lenses.

RESULTS

Patients desire comfort, clarity of vision, and prolonged contact lens wear when contact lenses are used to correct refractive error. Practitioners desire patient satisfaction but also require maintenance of the integrity of the eye and no complications that jeopardize vision or health of the eye. Improvements in the oxygen permeability of the contact lens materials, design of the contact lens and its surface, and solutions for the maintenance of the lens have reduced but not eliminated the risks of infection, inflammation, and conjunctival papillary reaction associated with contact lens wear. The lessons of past and recent history suggest that patient education and practitioner participation in the management of contact lens wear continue to be critical factors for patient satisfaction and safety in the extended wear of contact lenses.

CONCLUSIONS

The availability of highly oxygen permeable contact lenses has increased the tolerance and safety of extended contact lens wear, but patient instruction and education in proper use and care of lenses is required and caution is advised.

Microbial Keratitis in Prospective Studies of Extended Wear With Disposable Hydrogel Contact Lenses

PURPOSE

To report the annualized incidence of microbial keratitis with extended wear of low oxygen transmissible (Dk/t) disposable soft contact lenses from prospective postmarket clinical trials.

METHODS

Seven hundred ninety subjects were enrolled at the L.V. Prasad Eye Institute (LVPEI), Hyderabad, India from March 1993 to March 2000, resulting in 1231 patient eye years, and 167 subjects were enrolled at the Cornea and the Contact Lens Research Unit (CCLRU), Sydney, Australia from July 1987 to December 1999, resulting in 842 patient eye years.

RESULTS

The annualized incidence of microbial keratitis per 10,000 eyes per year of lens wear was 32.5 (95% CI 8.9 to 83.2) for LVPEI, 23.8 (95% CI=2.9 to 85.8) for CCLRU; when data are combined across both centers, the incidence was 28.9 (95% CI=10.6 to 63) per 10,000 eyes per year of lens wear. This equates to 57.0 per 10,000 wearers or 1 in 173 wearers per year of lens wear. All events were rated as slight to moderate in severity and did not result in visual loss. Two events were described to highlight the challenges in diagnosis and treatment of microbial keratitis.

CONCLUSIONS

The incidence of microbial keratitis with extended wear of low-Dk/t disposable lenses was higher in these prospective studies (1 in 210 wearers per year at CCLRU and 1 in 154 wearers per year at LVPEI) than that seen in retrospective population-based surveillance studies (1 in 500 wearers per year). Practitioners and patients should always be alert to signs and symptoms, and practitioners should adopt conservative strategies for diagnosis and management of contact lens-related adverse events.

Clinical characterization of corneal infiltrative events observed with soft contact lens wear

PURPOSE

Corneal infiltrates are commonly observed during adverse reactions associated with contact lens wear. Broad ranges of presentations are encountered, and there is no well-established classification system. The aim of this paper is to categorize corneal infiltrates associated with soft lens wear and present the typical clinical characteristics associated with each type of event.

METHODS

All events of corneal infiltrates occurring in soft contact lens clinical trials over 10 years (9 years retrospective and 1 year prospective) and conducted at two contact lens research centers were reviewed by a panel of experts comprising ophthalmologists, optometrists, and other biologic scientists. Classification of each event was based on assessment of a range of signs and symptoms by the review panel.

RESULTS

A classification scheme was devised to distinguish infiltrative events that were serious and symptomatic (microbial keratitis), clinically significant and symptomatic (contact lens-induced peripheral ulcer, contact lens-induced acute red eye, infiltrative keratitis), and clinically nonsignificant and asymptomatic (asymptomatic infiltrative keratitis and asymptomatic infiltrates).

CONCLUSION

Corneal infiltrates can be classified into six distinct categories. This classification scheme, based on clinical characteristics, should aid diagnosis, management, and treatment of corneal infiltrates as well as assisting investigations into the etiology of each of these conditions.

Is there a question of safety with continuous wear?

The availability of silicone-containing hydrogel contact lenses (SCHCLs) has refocused attention on the risks associated with continuous wear (CW). The major barrier to optometrists prescribing CW in Western societies is a perceived danger of microbial keratitis (MK). This perception has been shaped largely by educators who have developed their opinions from case reports in the ophthalmic literature, sensationalist lay press reports and later epidemiological studies and from prominent physicians in tertiary referral centres, following an increased incidence of MK with extended wear (EW) of traditional hydrogel materials. The basis for the perceived lack of safety is the higher risk of MK with EW compared to daily wear and incidence figures that suggest an unacceptable level of MK in a population at risk, albeit a small risk on an individual basis. In this paper, I re-evaluate the validity of the previous data and challenge the conclusions regarding the nature of the risk with traditional hydrogel lens materials. Areas under scrutiny include diagnostic criteria, morbidity caused by different micro-organisms, potential bias in studies and reports, analysis of visual outcomes and cost to the community, and improvements over time in the understanding and handling of contact lens-related complications. Significant loss of vision with EW appears to be less frequent than is the common perception. When the risks are placed in the perspective of other data such as that for refractive surgery, the arguments against EW do not seem so compelling. The high oxygen transmissibility of SCHCLs may enable safe CW but a large-scale epidemiological study is needed to allay remaining doubts. Any such future studies should note the points outlined in this document.