TRPV1 corneal neuralgia mutation: Enhanced pH response, bradykinin sensitization, and capsaicin desensitization.

The factors that contribute to pain after nerve injury remain incompletely understood. Laser-assisted in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) are common surgical techniques to correct refractive errors. After LASIK or PRK, a subset of patients suffers intense and persistent pain, of unknown origin, described by patients as feeling like shards of glass in their eye. Here, we evaluated a TRPV1 variant, p.V527M, found in a 49-y-old woman who developed corneal pain after LASIK and subsequent PRK enhancement, reporting an Ocular Surface Disease Index score of 100. Using patch-clamp and Ca2+ imaging, we found that the V527M mutation enhances the response to acidic pH. Increasing proton concentration induced a stronger leftward shift in the activation curve of V527M compared to WT, resulting in channel activity of the mutant in acidic pH at more physiological membrane potentials. Finally, comparing the responses to consecutive applications of different agonists, we found in V527M channels a reduced capsaicin-induced desensitization and increased sensitization by the arachidonic acid metabolite 12-hydroxyeicosatetraenoic acid (12-HETE). We hypothesize that the increased response in V527M channels to protons and enhanced sensitization by 12-HETE, two inflammatory mediators released in the cornea after tissue damage, may contribute to the pathogenesis of corneal neuralgia after refractive surgery.

Nav1.7 P610T mutation in two siblings with persistent ocular pain after corneal axon transection: impaired slow inactivation and hyperexcitable trigeminal neurons.

Despite extensive study, the mechanisms underlying pain after axonal injury remain incompletely understood. Pain after corneal refractive surgery provides a model, in humans, of the effect of injury to trigeminal afferent nerves. Axons of trigeminal ganglion neurons that innervate the cornea are transected by laser-assisted in situ keratomileusis (LASIK). Although most patients do not experience postoperative pain, a small subgroup develop persistent ocular pain. We previously carried out genomic analysis and determined that some patients with persistent pain after axotomy of corneal axons during refractive surgery carry mutations in genes that encode the electrogenisome of trigeminal ganglion neurons, the ensemble of ion channels and receptors that regulate excitability within these cells, including SCN9A, which encodes sodium channel Nav1.7, a threshold channel abundantly expressed in sensory neurons that has been implicated in a number of pain-related disorders. Here, we describe the biophysical and electrophysiological profiling of the P610T Nav1.7 mutation found in two male siblings with persistent ocular pain after refractive surgery. Our results indicate that this mutation impairs the slow inactivation of Nav1.7. As expected from this proexcitatory change in channel function, we also demonstrate that this mutation produces increased spontaneous activity in trigeminal ganglion neurons. These findings suggest that this gain-of-function mutation in Nav1.7 may contribute to pain after injury to the axons of trigeminal ganglion neurons.NEW & NOTEWORTHY Mechanisms underlying pain after axonal injury remain elusive. A small subgroup of patients experience pain after corneal refractive surgery, providing a human pain model after well-defined injury to axons. Here we analyze a mutation (P610T) in Nav1.7, a threshold sodium channel expressed in nociceptors, found in two siblings with persistent ocular pain after refractive surgery. We show that it impairs channel slow inactivation, thereby triggering inappropriate repetitive activity in trigeminal ganglion axons that signal eye pain.

Role of therapeutic contact lenses in management of corneal disease.

PURPOSE OF REVIEW: The current review highlights areas of innovation and research in the use of contact lenses in the treatment of corneal ectasia and ocular surface disease. RECENT FINDINGS: A series of academic reports were published by a committee of experts reviewing evidence-based practice patterns of contact lens use. There continues to be active research in the use of contact lenses in the management of keratoconus, including mini-scleral lenses, custom impression-based scleral lenses and wavefront-guided scleral lenses. Recent reports on contact lenses for ocular surface disease were primarily reviews, retrospective case reports or case series, with publications on contact lens use in corneal epithelial defects, graft-vs.-host disease, limbal stem cell deficiency and neurotrophic keratitis. There are recent publications on advances in drug-eluting contact lenses. SUMMARY: Corneal specialists should be aware of current advances in the field of contact lens expanding their use in corneal ectasia and ocular surface disease.

Contact Lenses for Ocular Surface Disease.

ABSTRACT: Ocular surface disease can be difficult to manage, causing patients discomfort and vision loss. Therapeutic contact lenses are an important treatment option that is often neglected because it is conventional wisdom that eyes that are dry or irritated are not good candidates for contact lens. In this focused review, we consider the substantial literature on the use of bandage soft contact lenses (BSCL), scleral lenses, and customized prosthetic devices in the management of ocular graft-vs-host disease. Reports on BSCLs for recurrent corneal erosion are reviewed, as is literature on scleral lenses and prosthetic replacement of the ocular surface ecosystem treatment for Stevens-Johnson syndrome. Clinical pearls for fitting BSCLs are presented, and the issue of antibiotic prophylaxis is considered.

Contact Lens Safety for the Correction of Refractive Error in Healthy Eyes.

ABSTRACT: Contact lenses are a safe and effective method for correction of refractive error and worn by an estimated 45 million Americans. Because of the widespread availability and commercial popularity of contact lenses, it is not well appreciated by the public that contact lenses are U.S. Food and Drug Administration (FDA)-regulated medical devices. Contact lenses are marketed in numerous hard and soft materials that have been improved over decades, worn in daily or extended wear, and replaced in range of schedules from daily to yearly or longer. Lens materials and wear and care regimens have impact on the risks of contact lens-related corneal inflammatory events and microbial keratitis. This article reviews contact lens safety, with specific focus on the correction of refractive error in healthy eyes.

American Academy of Optometry Microbial Keratitis Think Tank.

SIGNIFICANCE: Think Tank 2019 affirmed that the rate of infection associated with contact lenses has not changed in several decades. Also, there is a trend toward more serious infections associated with Acanthamoeba and fungi. The growing use of contact lenses in children demands our attention with surveillance and case-control studies. PURPOSE: The American Academy of Optometry (AAO) gathered researchers and key opinion leaders from around the world to discuss contact lens-associated microbial keratitis at the 2019 AAO Annual Meeting. METHODS: Experts presented within four sessions. Session 1 covered the epidemiology of microbial keratitis, pathogenesis of Pseudomonas aeruginosa, and the role of lens care systems and storage cases in corneal disease. Session 2 covered nonbacterial forms of keratitis in contact lens wearers. Session 3 covered future needs, challenges, and research questions in relation to microbial keratitis in youth and myopia control, microbiome, antimicrobial surfaces, and genetic susceptibility. Session 4 covered compliance and communication imperatives. RESULTS: The absolute rate of microbial keratitis has remained very consistent for three decades despite new technologies, and extended wear significantly increases the risk. Improved oxygen delivery afforded by silicone hydrogel lenses has not impacted the rates, and although the introduction of daily disposable lenses has minimized the risk of severe disease, there is no consistent evidence that they have altered the overall rate of microbial keratitis. Overnight orthokeratology lenses may increase the risk of microbial keratitis, especially secondary to Acanthamoeba, in children. Compliance remains a concern and a significant risk factor for disease. New insights into host microbiome and genetic susceptibility may uncover new theories. More studies such as case-control designs suited for rare diseases and registries are needed. CONCLUSIONS: The first annual AAO Think Tank acknowledged that the risk of microbial keratitis has not decreased over decades, despite innovation. Important questions and research directions remain.

Corneal Infections Associated with Sleeping in Contact Lenses - Six Cases, United States, 2016-2018.

Contact lenses, when worn and cared for properly, are a safe and effective form of vision correction used by an estimated 45 million Americans. However, contact lens wearers are at risk for contact lens-related eye infections, especially when wearers do not practice proper contact lens wear and care habits. These infections, affecting the cornea and known as microbial keratitis (Figure), can lead to serious adverse health outcomes. Because contact lenses are regulated by the Food and Drug Administration (FDA) as medical devices, contact lens-related corneal infections should be reported to FDA as an adverse event. To illustrate their serious health implications, six cases of contact lens-related corneal infection, in which sleeping in lenses was reported as the main risk factor, are presented. Consequences of infection reported among the identified cases included the need for frequent administration of antibiotic eye drops, multiple follow-up medical appointments, and permanent eye damage. Health education measures directed toward contact lens wearers should emphasize raising awareness of the risks of sleeping in contact lenses as well as adherence to all recommendations for the wear and care of contact lenses. Additional measures are needed to educate eye care professionals about the need to report contact lens-related corneal infections to MedWatch, the FDA Safety Information and Adverse Event Reporting program (https://www.fda.gov/MedWatch/).

Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) Treatment for Complications After LASIK.

OBJECTIVES: To report experience with Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) treatment for complications after laser in situ keratomileuisis (LASIK). METHODS: Retrospective review of clinical and manufacturing records. A database of patients who underwent PROSE treatment from 1992 to 2007 was searched to yield all patients with history of LASIK. Primary indication for PROSE treatment and year of LASIK is reported as well as history of contact lens intolerance and pretreatment and posttreatment best-corrected visual acuity (BCVA). RESULTS: From 1992 to 2007, 44 patients (75 eyes) with history of LASIK underwent PROSE treatment. Patients with corneal ectasia (n=23, 52%) comprise the largest group of patients, followed by those with other optical aberrations (n = 14.32%), dry eye (n = 4.9%), and corneal neuralgia (n=3.7%). Thirteen patients (30%) had more than one indication for PROSE treatment. The majority (71%) of patients referred for PROSE treatment had LASIK between 1998 and 2000, including every patient with aberrations as primary indication. Eighty-six percent of all patients had history of contact lens intolerance. Eighty-four percent of eyes showed improvement in BCVA after PROSE treatment, mean -0.3LogMAR, (P < 0.0001, 2-tailed paired t test, n = 75). CONCLUSIONS: PROSE treatment is an effective option for management of ectasia, cornea first surface aberrations, dry eye, and corneal neuralgia after LASIK, even in patients who are contact lens intolerant.

PROSE Treatment for Ocular Chronic Graft-Versus-Host Disease as a Clinical Network Expands.

BACKGROUND: Keratoconjunctivitis sicca occurs in 40% to 90% of patients with ocular chronic graft-versus-host disease (cGVHD). Ocular symptoms can have profound effects in both the visual function and quality of life of patients with GVHD. We report the impact of prosthetic replacement of the ocular surface ecosystem (PROSE) treatment in patients with cGVHD as a clinical network expands. METHODS: We queried the BostonSight PROSE manufacturing database from January 2002 to December 2011. Patients treated for ocular cGVHD were reported by age, gender, year, and network site where the treatment was undertaken. The baseline and six-month follow-up scores of visual function using a standardized validated instrument, the National Eye Institute Visual Function Questionnaire (NEI VFQ-25), were evaluated for a period in 2006 and again in 2010 after network expansion had occurred. RESULTS: A total of 407 patients with a male:female ratio of 226:181, mean age was 51 years with ocular cGVHD underwent PROSE treatment from January 2002 to December 2011. By 2011, 67% of all cases were treated at network clinics. Baseline characteristics of patients treated throughout the network in 2010 were similar to that of 2006 and 2010 cohorts from the main center. There was a significant improvement of 41 points (P<0.001) in composite NEI VFQ score among patients treated across the network in 2010, similar to the improvement of 30 points (P<0.001) seen among the patients treated at the main center in 2010. There was a trend toward lower baseline self-reported general health status (SRGHS) and VFQ scores among patients treated at network clinics, suggesting that expansion of the network allows treatment of sicker patients (lower general health status) or those more severely affected by ocular cGVHD. CONCLUSIONS: PROSE treatment of ocular cGVHD has increased in the last decade with the establishment of BostonSight network clinics across the United States. Patients treated at network clinics showed similar levels of baseline visual function and SRGHS, and achieved a similar high level of improvement in visual function as those treated at the main center. Patient-reported measures of functional status are useful in evaluating treatment options for patients with cGVHD. PROSE treatment has significant positive impact on the visual function of patients with ocular cGVHD regardless of whether the patient is treated at the main center or at a network site.

Prosthetic replacement of the ocular surface ecosystem as treatment for ocular surface disease in patients with a history of Stevens-Johnson syndrome/toxic epidermal necrolysis.

PURPOSE: To report the visual outcomes of prosthetic replacement of the ocular surface ecosystem (PROSE) treatment in patients with ocular surface disease related to Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). DESIGN: Retrospective cohort study. SUBJECTS: We included 86 patients (167 eyes) with history of SJS/TEN who underwent PROSE treatment from January 1, 2006, to January 1, 2011. METHODS: Etiology, previous interventions, change in visual acuity, change in visual function, and duration of follow-up are reported. Paired t test and Friedman test with Dunn's post hoc test for multiple comparisons were used for statistical analysis. MAIN OUTCOME MEASURES: Visual acuity at last follow-up and visual function based on the National Eye Institute 25-item Visual Functioning Questionnaire (NEI VFQ-25) at 6 months. RESULTS: We treated 35 males and 51 females with a history of SJS/TENS; median age was 36 years. The most common reported etiologies for SJS/TENS were antibiotics (n = 25), ibuprofen (n = 15), and lamotrigine (n = 11). The median visual acuity at the initial visit was 20/60 (range, 20/400-20/25; 0.48 logarithm of the minimum angle of resolution [logMAR]), and the visual acuity at completion of customization was 20/25 (range, 20/200-20/20; 0.096 logMAR; P < 0.001), with no decline in median acuity at the end of follow-up. Median duration of follow-up was 16 months. There was a significant improvement in the visual function of the patients based on the NEI VFQ-25 questionnaire (mean of 48 points at baseline vs. mean of 72 points at 6 months; P < 0.001). In addition, there was also an improvement in the self-reported general health of the patients (mean of 57 points at baseline vs. mean of 65 points at 6 months; P < 0.01). CONCLUSIONS: In a large cohort of patients with chronic ocular surface disease related to SJS/TEN, PROSE treatment offers sustained and significant large improvement in visual function and acuity.

Advances in scleral lenses for refractive surgery complications.

PURPOSE OF REVIEW: The last two decades have brought advances in materials and manufacturing of large diameter rigid gas-permeable contact lenses, and a greater appreciation of the role of scleral lenses for therapeutic indications. The purpose of this review is to provide an update on the use of rigid gas-permeable scleral lenses in the management of patients with complications after refractive surgery. RECENT FINDINGS: There are recent reports on clinical experience with specific scleral lens designs from single institutions in cohorts that include patients who have undergone refractive surgery. Typically, these are patients with 'irregular corneas' after radial keratotomy or LASER assisted in-situ keratomileusis, but patients with keratectasia, dry eye syndrome, and corneal neuralgia are also reported. Visual outcomes and wearing success rates are high in these reports, although outcomes for refractive surgery patients are not reported separately. SUMMARY: Clinicians who encounter patients with complications after corneal refractive surgery should be aware of advances in scleral lenses. Scleral lenses are an alternative to surgical intervention in patients who might otherwise be considered poor contact lens candidates.