Corneal conjunctivalisation in long-standing contact lens wearers

A Review of Contact Lens-Induced Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) is a pathologic condition caused by the dysfunction and destruction of stem cells, stem cell precursors and limbal cell niche in the corneal epithelium, leading to severe conjunctivalization of the cornea. Etiologies for LSCD span from congenital (aniridia), traumatic (chemical or thermal injuries), autoimmune (Stevens-Johnson syndrome) and iatrogenic disease to contact lens (CL) wear. Of these, CL wear is the least understood and is often a subclinical cause of LSCD. Even with recent advances in LSCD research, limitations persist in establishing the pathogenesis and treatment guidelines for CL-induced LSCD. A literature search was conducted to include original articles containing patients with CL-induced LSCD. This review will critically discuss the complex pathophysiology behind CL-induced LSCD, the underlying risk factors and epidemiology of the disease as well as methods to obtain a diagnosis. Various treatment options will be reviewed based on proposed treatment strategies.

The Multifold Etiologies of Limbal Stem Cell Deficiency: A Comprehensive Review on the Etiologies and Additional Treatment Options for Limbal Stem Cell Deficiency

Given the various ocular manifestations of limbal stem cell insufficiency, an awareness of the genetic, acquired, and immunological causes and associated additional treatments of limbal stem cell deficiency (LSCD) is essential for providers. We performed a comprehensive review of the literature on the various etiologies and specific therapies for LSCD. The resources utilized in this review included Medline (PubMed), Embase, and Google Scholar. All English-language articles and case reports published from November 1986 through to October 2022 were reviewed in this study. There were collectively 99 articles on these topics. No other exclusion criteria were applied. Depending on the etiology, ocular manifestations of limbal stem cell deficiency range from dry eye syndrome and redness to more severe outcomes, including corneal ulceration, ocular surface failure, and vision loss. Identifying the source of damage for LSCD is critical in the treatment process, given that therapy may extend beyond the scope of the standard protocol, including artificial tears, refractive surgery, and allogeneic stem cell transplants. This comprehensive review of the literature demonstrates the various genetic, acquired, and immunological causes of LSCD and the spectrum of supplemental therapies available.

Ocular injury progression and cornea histopathology from chloropicrin vapor exposure: Relevant clinical biomarkers in mice

Ocular tissue is highly sensitive to chemical exposures. Chloropicrin (CP), a choking agent employed during World War I and currently a popular pesticide and fumigating agent, is a potential chemical threat agent. Accidental, occupational, or intentional exposure to CP results in severe ocular injury, especially to the cornea; however, studies on ocular injury progression and underlying mechanisms in a relevant in vivo animal model are lacking. This has impaired the development of effective therapies to treat the acute and long-term ocular toxicity of CP. To study the in vivo clinical and biological effects of CP ocular exposure, we tested different CP exposure doses and durations in mice. These exposures will aid in the study of acute ocular injury and its progression as well as identify a moderate dose to develop a relevant rodent ocular injury model with CP. The left eyes of male BALB/c mice were exposed to CP (20% CP for 0.5 or 1 min or 10% CP for 1 min) using a vapor cap, with the right eyes serving as controls. Injury progression was evaluated for 25 days post-exposure. CP-exposure caused a significant corneal ulceration and eyelid swelling which resolved by day 14 post exposure. In addition, CP-exposure caused significant corneal opacity and neovascularization. Development of hydrops (severe corneal edema with corneal bullae) and hyphema (blood accumulation in the anterior chamber) was observed as advanced CP effects. Mice were euthanized at day 25 post-CP-exposure, and the eyes were harvested to further study the corneal injury. Histopathological analyses showed a significant CP-induced decrease in corneal epithelial thickness and increased stromal thickness with more pronounced damage, including stromal fibrosis, edema, neovascularization, trapped epithelial cells, anterior and posterior synechiae, and infiltration of inflammatory cells. Loss of the corneal endothelial cells and Descemet's membrane could be associated with the CP-induced corneal edema and hydrops which could lead to long term term pathological conditions. Although exposure to 20% CP for 1 min caused more eyelid swelling, ulceration, and hyphema, similar effects were observed with all CP exposures. These novel findings following CP ocular exposure in a mouse model outline the corneal histopathologic changes that associate with the continuing ocular clinical effects. The data are useful in designing further studies to identify and correlate the clinical and biological markers of CP ocular injury progression with acute and long-term toxic effects on cornea and other ocular tissues. We take a crucial step towards CP ocular injury model development and in pathophysiological studies to identify molecular targets for therapeutic interventions.

A pilot study investigating the effect of extended contact lens wear on limbal and central corneal morphology

PURPOSE

To investigate the effect of long-term extended soft contact lens wear on limbal and central corneal cell morphology, and limbal architecture.

METHODS

Each participant attended a study visit involving in vivo confocal microscopy of central corneal and limbal epithelium. Scans were graded by five masked graders for three features: central epithelial irregularity, limbal epithelial irregularity and the prominence of palisades of Vogt. The variability of grades between different graders and the difference of grades between extended wearers and daily soft/non-contact lens wearers were assessed.

RESULTS

Nineteen participants (9 extended soft contact lens wearers and 10 daily soft/non-contact lens wearers) aged 31-65 years were enrolled in this study. Scans from 37 eyes were included in the analysis. Agreement between graders for each feature was moderate to good with inter class correlation >0.7. While there were no significant differences in central epithelial cell irregularity (p = 0.527) and the prominence of palisade of Vogt (p = 0.182) between extended or daily soft/non-contact lens wearers, limbal epithelial cell irregularity showed a trend with increased irregularity in extended soft contact lens wearers (p = 0.091).

CONCLUSIONS

While no differences in limbal cell morphology and structureor central epithelial cell wasfound in thissubjective grading study of extended wearers compared to daily soft/non-contact lens wearers, further studies using a larger sample size or a longitudinal study design are warranted.

Corneal Epithelial Stem Cells-Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.

Limbal stem cell diseases

The function of limbal stem/progenitor cells (LSCs) is critical to maintain corneal epithelial homeostasis. Many external insults and intrinsic defects can be deleterious to LSCs and their niche microenvironment, resulting in limbal stem cell dysfunction or deficiency (LSCD). Ocular comorbidities, frequent in eyes with LSCD, can exacerbate the dysfunction of residual LSCs, and limit the survival of transplanted LSCs. Clinical presentation and disease evolution vary among different etiologies of LSCD. New ocular imaging modalities and molecular markers are now available to standardize the diagnosis criteria and stage the severity of the disease. Medical therapies may be sufficient to reverse the disease if residual LSCs are present. A stepwise approach should be followed to optimize the ocular surface, eliminate the causative factors and treat comorbid conditions, before considering surgical interventions. Furthermore, surgical options are selected depending on the severity and laterality of the disease. The standardized diagnostic criteria to stage the disease is necessary to objectively evaluate and compare the efficacy of the emerging customized therapies.

CLEAR - Medical use of contact lenses

The medical use of contact lenses is a solution for many complex ocular conditions, including high refractive error, irregular astigmatism, primary and secondary corneal ectasia, disfiguring disease, and ocular surface disease. The development of highly oxygen permeable soft and rigid materials has extended the suitability of contact lenses for such applications. There is consistent evidence that bandage soft contact lenses, particularly silicone hydrogel lenses, improve epithelial healing and reduce pain in persistent epithelial defects, after trauma or surgery, and in corneal dystrophies. Drug delivery applications of contact lens hold promise for improving topical therapy. Modern scleral lens practice has achieved great success for both visual rehabilitation and therapeutic applications, including those requiring retention of a tear reservoir or protection from an adverse environment. This report offers a practical and relevant summary of the current evidence for the medical use of contact lenses for all eye care professionals including optometrists, ophthalmologists, opticians, and orthoptists. Topics covered include indications for use in both acute and chronic conditions, lens selection, patient selection, wear and care regimens, and recommended aftercare schedules. Prevention, presentation, and management of complications of medical use are reviewed.

Contact Lens Induced Limbal Stem Cell Deficiency: Clinical Features in Korean Patients

Purpose

To describe the clinical features of Korean patients with contact lens-induced limbal stem cell deficiency (CL-LSCD).

Methods

Medical records of 22 patients who were diagnosed with CL-LSCD between 2014 and 2019 were reviewed retrospectively. Outcome measures included demographics, clinical presentation, treatment, clinical course, and pattern of contact lens (CL) wear.

Results

Forty-two eyes of 22 patients were found to have typical changes associated with CL-LSCD. Twenty (91%) patients were women and mean age was 36 ± 12 years. All patients had myopia with mean spherical equivalent of −7.52 ± 3.2 diopter. Twenty (91%) patients had bilateral disease and the location of limbal involvement was diffuse in 20 eyes (47.6%) and partial in 22 eyes (52.4%, superior in 20 eyes and inferior in 2 eyes). Fourteen (63.6%) patients complained of decreased visual acuity. Average period of CL wear was 14 ± 9 years. Four patients used cosmetic colored CLs and four patients had a history of overnight CL wear. All 12 patients who completed follow-up (28 ± 42 weeks) showed improvement in visual acuity and ocular surface condition after cessation of CL wear and medical treatment. Of them, five (42%) patients showed full recovery while seven (58%) showed partial recovery.

Conclusions

If a patient with a history of CL wear for an extended period of time presents with decreased visual acuity, practitioners should perform detailed examinations with suspicion of CL-LSCD, including fluorescein staining. CL-LSCD is usually reversible and close follow-up with conservative treatment is recommended as the initial treatment option.

Decellularized Human Stromal Lenticules Combine with Corneal Epithelial-Like Cells: A New Resource for Corneal Tissue Engineering

The lack of donor corneal tissue or the immunological rejection remains a challenge for individuals with limbal stem cell deficiency (LSCD) who are treated with keratoplasty. Numerous lenticules which were extracted by small incision lenticule extraction (SMILE) appear to be useful materials for keratoplasty. In order to reduce the incidence of allograft rejection, lenticules would be decellularized. Lenticules which were treated with liquid nitrogen and nucleases had no cellular and nuclear materials remained. Human induced pluripotent stem cells (iPSCs) can be generated from the patient who requires keratoplasty, offering an autologous alternative and eliminating the risk of graft rejection. We found that BMP-4, RA, N-2 supplement, hEGF, B27, decellularized human stromal lenticules, conditioned medium, or induction medium promoted the differentiation of human iPSCs with high purity. The results showed that human iPSCs cultured for 4 days in differentiation medium A, 14 days in condition medium, and 1 week in induction medium on decellularized human stromal lenticules developed markedly higher expression of the markers P63, CK3, and CK12 than did those in the other methods. The level of gene expression of the epithelial and pluripotency markers and analysis by scanning electron microscopy and immunohistochemistry also showed successful differentiation. After inducing differentiation in vitro, corneal epithelial-like cells were induced. In the study, we investigated the possibility of a new resource for corneal tissue engineering.

Bevacizumab Induces Upregulation of Keratin 3 and VEGFA in Human Limbal Epithelial Cells in Vitro

Topical application of vascular endothelial growth factor A (VEGFA) inhibitors including Bevacizumab is used for antiangiogenic therapy at the ocular surface. While clinical studies have suggested that this approach is well-tolerated, the effect of the drug on limbal epithelial stem cells has not been studied. In this study, the effect of Bevacizumab on phenotype and functionality of putative limbal epithelial stem cells (SC) was investigated. The effect of Bevacizumab on human limbal epithelial cells was assessed in terms of metabolic activity and scratch wound closure. The different treatment groups featured no difference in proliferation and colony forming efficiency (CFE) of limbal epithelial cells or their putative SC marker expression. A significant delay in scratch closure of all the Bevacizumab-treated groups was detected at 4 h. RNA and protein quantification indicated a dose-responsive increase of keratin 3. VEGFA RNA expression also increased while VEGFC and D as well as VEGFR1, 2 and 3 were unchanged. This study highlights previously unknown effects of Bevacizumab on cultured putative limbal epithelial SC: a dose-related increase of keratin 3, an increase in VEGFA as well as a delay in scratch wound closure. These in vitro data should be considered when using Bevacizumab in the context of limbal epithelial SC transplantation.

Contact lens wear and the diabetic corneal epithelium: A happy or disastrous marriage?

Diabetes mellitus is an epidemic in the US and abroad. With the advent of new contact lens technology, the use of contact lenses as glucose sensors in lieu of the traditional finger stick is quickly becoming realized. This has the potential to rapidly expand the contact lens market into this growing patient population. The independent cellular and physiological effects of contact lens wear and diabetes on the corneal epithelium have been described. However, little evidence exists to date to support whether there is increased risk associated with contact lens wear in diabetes. The focus of this review is to discuss what is known about the cellular effects of contact lenses on the corneal epithelium, the pathophysiological changes in the corneal epithelium that occur in diabetes, and whether an increased risk for corneal epithelial damage and/or infection may negatively impact safety in diabetic contact lens wearers. Available data indicates that there are inherent risks associated with contact lens wear in diabetics. Importantly, eye care practitioners fitting contact lenses in the diabetic patient need to carefully consider the duration of disease, the level of glycemic control, the presence of retinopathy, and the patient's overall health.

Contact Lens-induced Limbal Stem Cell Deficiency

Limbal stem cell deficiency (LSCD) is a pathologic condition caused by the dysfunction and/or destruction of stem cell precursors of the corneal epithelium, typified clinically by corneal conjunctivalization. The purpose of this review is to critically discuss a less well-known cause of limbal stem cell disease: contact lens (CL) wear. A literature search was conducted to include original articles containing patients with CL-induced LSCD. This review describes epidemiology, diagnostic strategies, pathogenesis, differential diagnosis, and treatment modalities for this condition.

Quantitative assessment of central and limbal epithelium after long-term wear of soft contact lenses and in patients with dry eyes: a pilot study

PurposeAnalysis of microstructural alterations of corneal and limbal epithelial cells in healthy human corneas and in other ocular conditions.Patients and methodsUnilateral eyes of three groups of subjects include healthy volunteers (G1, n=5), contact lens wearers (G2, n=5), and patients with dry eyes (G3, n=5) were studied. Imaging of basal (BC) and intermediate (IC) epithelial cells from central cornea (CC), corneal limbus (CL) and scleral limbus (SL) was obtained by in vivo confocal microscopy (IVCM). An appropriate image analysis algorithm was used to quantify morphometric parameters including mean cell area, compactness, solidity, major and minor diameter, and maximum boundary distance.ResultsThe morphometric parameters of BC and IC demonstrated no significant differences (P>0.05) between groups. Comparison between three corneal locations (CC, CL, and SL) within the groups showed significant differences (P<0.05) with mean values of cell area, compactness, solidity, and major and minor diameter of BC that increase from CC to limbus. The BC were round and regular in the central cornea (P<0.05) compared with CL and SL.ConclusionsIVCM enables high-quality confocal images from central corneal and limbal epithelium. This quantitative study demonstrated morphological differences in the basal and intermediate epithelium between limbus and central cornea, and found no differences between contact lens wearers, dry eyes, and normal subjects.

Limbal Stem Cell Transplantation for Soft Contact Lens Wear-Related Limbal Stem Cell Deficiency

PURPOSE

To describe the outcomes of limbal stem cell transplantation in eyes with limbal stem cell deficiency related to soft contact lens wear.

DESIGN

Retrospective interventional case series.

METHODS

Institutional database search at the Cincinnati Eye Institute revealed 9 patients (14 eyes) who underwent limbal stem cell transplantation with systemic immunosuppression for soft contact lens wear-related limbal stem cell deficiency. Outcome measures included patient demographics, symptoms, best-corrected visual acuity, ocular surface stability, adverse events, and additional surgeries required.

RESULTS

Average patient age at time of surgery was 46.6 ± 11.1 years (range 20-60 years). Average duration of follow-up was 28 ± 19.1 months (range 12-70 months). Preoperative best-corrected visual acuity (BCVA) was 20/40 or worse in all eyes (average 20/70, range 20/40-20/250) and patient symptoms included foreign body sensation, tearing, redness, and/or pain. Four eyes (29%) underwent living-related conjunctival limbal allograft and 10 eyes (71%) underwent cadaver-donor keratolimbal allograft surgery. Topical and systemic immunosuppression was used in all patients. At final follow-up after limbal stem cell transplantation, there was a stable ocular surface in 12 of 14 eyes (86%) and improvement in BCVA to 20/30 or better and complete resolution of patient symptoms in all except 1 patient who had significant rosacea blepharokeratoconjunctivitis, whose BCVA remained at 20/150 and 20/60, in right and left eyes, respectively. The most common adverse event was an increase in intraocular pressure in 8 of 14 eyes (57%), requiring topical antiglaucoma treatment. Ten of 14 eyes (71%) underwent cataract extraction related to topical steroid use. No eyes required subsequent penetrating keratoplasty.

CONCLUSION

Limbal stem cell transplantation is a viable option for the management of soft contact lens wear-related limbal stem cell deficiency in young healthy patients. Early intervention prior to subepithelial fibrosis can lead to good visual outcomes with no need for subsequent cornea transplant. Co-management with a solid organ transplant specialist is helpful for the monitoring and management of systemic adverse events related to patient systemic immunosuppression.

Differentiation of human limbal-derived induced pluripotent stem cells into limbal-like epithelium

Limbal epithelial stem cell (LESC) deficiency (LSCD) leads to corneal abnormalities resulting in compromised vision and blindness. LSCD can be potentially treated by transplantation of appropriate cells, which should be easily expandable and bankable. Induced pluripotent stem cells (iPSCs) are a promising source of transplantable LESCs. The purpose of this study was to generate human iPSCs and direct them to limbal differentiation by maintaining them on natural substrata mimicking the native LESC niche, including feederless denuded human amniotic membrane (HAM) and de-epithelialized corneas. These iPSCs were generated with nonintegrating vectors from human primary limbal epithelial cells. This choice of parent cells was supposed to enhance limbal cell differentiation from iPSCs by partial retention of parental epigenetic signatures in iPSCs. When the gene methylation patterns were compared in iPSCs to parental LESCs using Illumina global methylation arrays, limbal-derived iPSCs had fewer unique methylation changes than fibroblast-derived iPSCs, suggesting retention of epigenetic memory during reprogramming. Limbal iPSCs cultured for 2 weeks on HAM developed markedly higher expression of putative LESC markers ABCG2, ΔNp63α, keratins 14, 15, and 17, N-cadherin, and TrkA than did fibroblast iPSCs. On HAM culture, the methylation profiles of select limbal iPSC genes (including NTRK1, coding for TrkA protein) became closer to the parental cells, but fibroblast iPSCs remained closer to parental fibroblasts. On denuded air-lifted corneas, limbal iPSCs even upregulated differentiated corneal keratins 3 and 12. These data emphasize the importance of the natural niche and limbal tissue of origin in generating iPSCs as a LESC source with translational potential for LSCD treatment.

Biometric risk factors for corneal neovascularization associated with hydrogel soft contact lens wear in Korean myopic patients

PURPOSE

To investigate the biometric risk factors for corneal surface complications associated with hydrogel soft contact lens (SCL) fitting in myopic patients in Korea.

METHODS

This is a retrospective case-control study. The records of 124 subjects (124 eyes) who wore SCLs on a daily basis were reviewed. Thirty-one patients (31 eyes) who were diagnosed with corneal neovascularization (NV) while wearing SCLs were included in the complication group. Ninety-three age- and sex-matched patients (93 eyes) who wore SCLs, who did not have corneal NV and who visited our clinic for correction of refractive errors were included in the control group. The degree of spherical equivalent, astigmatism and corneal base curve radius (BCR) were compared in both groups.

RESULTS

Patients with NV exhibited poorer best corrected visual acuity and more myopia than controls (p = 0.008 and 0.006, respectively). In univariate analysis, highly myopic patients (-9 diopters [D] or higher) were more likely to experience NV (odds ratio [OR], 2.232; 95% confidence interval [CI], 1.602 to 3.105). High astigmatism (≥2 D) increased the risk of complications (OR, 2.717; 95% CI, 1.141 to 6.451). Steep cornea, in which BCR was <7.5 mm, also raised the risk of complications (OR, 4.000; 95% CI, 1.661 to 9.804). Flat cornea was not a risk factor for the development of NV.

CONCLUSIONS

High myopia, high astigmatism, and steep cornea seemed to be risk factors in the development of corneal NV in SCL wearers.

Medically reversible limbal stem cell disease: clinical features and management strategies

PURPOSE

To describe the clinical features and management strategies in patients whose limbal stem cell (LSC) disease reversed with medical therapy.

DESIGN

Retrospective case series.

PARTICIPANTS

Twenty-two eyes of 15 patients seen at 3 tertiary referral centers between 2007 and 2011 with 3 months or more of follow-up.

METHODS

Medical records of patients with medically reversible LSC disease were reviewed. Demographic data, causes, location and duration of disease, and medical inventions were analyzed.

MAIN OUTCOME MEASURES

Primary outcomes assessed included resolution of signs of LSC disease and improvement in visual acuity.

RESULTS

Causes of the LSC disease included contact lens wear only (13 eyes), contact lens wear in the setting of ocular rosacea (3 eyes), benzalkonium chloride toxicity (2 eyes), and idiopathic (4 eyes). Ophthalmologic findings included loss of limbal architecture, a whorl-like epitheliopathy, or an opaque epithelium arising from the limbus with late fluorescein staining. The superior limbus was the most common site of involvement (95%). The corneal epithelial phenotype returned to normal with only conservative measures, including lubrication and discontinuing contact lens wear in 4 patients (4 eyes), whereas in 11 patients (18 eyes), additional interventions were required after at least 3 months of conservative therapy. Medical interventions included topical corticosteroids, topical cyclosporine, topical vitamin A, oral doxycycline, punctal occlusion, or a combination thereof. All eyes achieved a stable ocular surface over a mean follow-up of 15 months (range, 4-60 months). Visual acuity improved from a mean of 20/42 to 20/26 (P < 0.0184).

CONCLUSIONS

Disturbances to the LSC function, niche, or both may be reversible with medical therapy. These cases, which represent a subset of patients with LSC deficiency, may be considered to have LSC niche dysfunction.

A simple alkaline method for decellularizing human amniotic membrane for cell culture

Human amniotic membrane is a standard substratum used to culture limbal epithelial stem cells for transplantation to patients with limbal stem cell deficiency. Various methods were developed to decellularize amniotic membrane, because denuded membrane is poorly immunogenic and better supports repopulation by dissociated limbal epithelial cells. Amniotic membrane denuding usually involves treatment with EDTA and/or proteolytic enzymes; in many cases additional mechanical scraping is required. Although ensuring limbal cell proliferation, these methods are not standardized, require relatively long treatment times and can result in membrane damage. We propose to use 0.5 M NaOH to reliably remove amniotic cells from the membrane. This method was used before to lyse cells for DNA isolation and radioactivity counting. Gently rubbing a cotton swab soaked in NaOH over the epithelial side of amniotic membrane leads to nearly complete and easy removal of adherent cells in less than a minute. The denuded membrane is subsequently washed in a neutral buffer. Cell removal was more thorough and uniform than with EDTA, or EDTA plus mechanical scraping with an electric toothbrush, or n-heptanol plus EDTA treatment. NaOH-denuded amniotic membrane did not show any perforations compared with mechanical or thermolysin denuding, and showed excellent preservation of immunoreactivity for major basement membrane components including laminin α2, γ1-γ3 chains, α1/α2 and α6 type IV collagen chains, fibronectin, nidogen-2, and perlecan. Sodium hydroxide treatment was efficient with fresh or cryopreserved (10% dimethyl sulfoxide or 50% glycerol) amniotic membrane. The latter method is a common way of membrane storage for subsequent grafting in the European Union. NaOH-denuded amniotic membrane supported growth of human limbal epithelial cells, immortalized corneal epithelial cells, and induced pluripotent stem cells. This simple, fast and reliable method can be used to standardize decellularized amniotic membrane preparations for expansion of limbal stem cells in vitro before transplantation to patients.

Severe limbal stem cell deficiency from contact lens wear: patient clinical features

PURPOSE

To describe characteristics of patients with severe limbal stem cell deficiency associated with contact lens (CL) wear.

DESIGN

Retrospective case series.

METHODS

Database search of patients with severe limbal stem cell deficiency related to CL wear was conducted. The charts of 12 patients (18 eyes) were reviewed. Outcome measures included patient demographics, CL type, duration of wear, indications for wear, symptoms, location and laterality of limbal stem cell deficiency, coexisting ocular disease, and treatment.

RESULTS

Mean patient age at presentation was 42 years (range, 19 to 58 years), and 8 patients (67%) were female. Mean duration of CL wear was 14.1 years (range, 1 to 20 years), 6 patients (50%) had bilateral disease, and all wore soft CLs for refractive error correction. Vision was decreased to a mean of 20/78 (range, 20/30 to 20/250) in all eyes. Fifteen eyes (83%) had photophobia, pain, or both. Findings leading to the diagnosis included whorl-like epitheliopathy, corneal conjunctivalization, and late fluorescein staining of the involved epithelium for at least 6 clock hours. On average, 10 clock hours (range, 6 to 12 clock hours) were involved, and 11 eyes (61%) had total ocular involvement. Conservative treatments failed in all eyes. Fourteen eyes (78%) underwent limbal stem cell transplantation with systemic immunosuppression.

CONCLUSIONS

Severe limbal stem cell deficiency related to CL wear is a clinical diagnosis that an ophthalmologist should recognize. Female patients, soft CLs, and extended duration of wear time are associated with this condition. Conservative measures may not reverse the disease, and limbal stem cell transplantation with systemic immunosuppression is a surgical option for these young and healthy patients.

The effects of silicone hydrogel lens wear on the corneal epithelium and risk for microbial keratitis

Previous studies using animal models and human clinical trials have demonstrated that the use of low-oxygen-transmissible contact lens materials produce corneal epithelial surface damage resulting in increased Pseudomonas aeruginosa (PA) adhesion and raft-mediated internalization into surface corneal epithelial cells. These findings led to the testable clinical predictions that (1) microbial keratitis (MK) risk is expected to be the greatest during the first 6 months of wear; (2) there is no difference between 6 and 30 night extended wear; and (3) that wear of hyperoxygen-transmissible lenses would reduce the reported incidence of infection. Subsequent epidemiologic studies have confirmed the first two predictions; however, increased oxygen transmissibility with silicone hydrogel (SiHy) lens wear has not altered the overall incidence of MK. In this review, more recent clinical and basic studies that investigate epithelial alterations and bacterial adhesion to corneal epithelial cells after the wear of SiHy lenses with and without concomitant exposure to chemically preserved multipurpose solutions (MPS) will be examined. The collective results of these studies demonstrate that even in the absence of lens-related hypoxia, MPS induce ocular surface changes during SiHy lens wear that are associated with a pathophysiologic increase in PA adherence and internalization in the corneal epithelium, and therefore, predict a greater risk for PA-MK. In addition, new data supporting an interactive role for inflammation in facilitating PA adherence and internalization in the corneal epithelium will also be discussed.

Management of focal limbal stem cell deficiency associated with soft contact lens wear

PURPOSE

To present the varying manifestations of and the treatment methods for corneal epitheliopathies because of focal limbal stem cell deficiency (LSCD) associated with soft contact lens (SCL) wear.

METHODS

The medical records of patients seen at 3 institutions who developed focal LSCD, based on clinical examination, that was attributed to SCL wear were reviewed. Information regarding the patients' demographics, contact lens wearing schedules, medical and surgical treatment modalities, and clinical and visual outcomes were recorded.

RESULTS

Eighteen eyes of 10 SCL wearers were found to have varying degrees of corneal epitheliopathy secondary to focal LSCD. Nine of the 10 patients (90%) were women, and the mean age of all patients was 35.1 years (range, 20-58 years). The mean duration of SCL wear was 15.2 years (range, 4-30 years). Two patients wore the lenses for 20 hours per day. Mean follow-up time was 7.0 months (range, 0.25-24 months). Visual acuity at first examination was affected in 10 of the 18 eyes (55.6%) and ranged from 20/30 to hand motions. The focal LSCD was found superiorly in all involved eyes and inferiorly in only 5 of 18 eyes (27.8%). The epitheliopathy resolved or stabilized in 11 eyes (61.1%) with cessation of SCL wear and use of artificial tears. Five eyes required topical corticosteroid eyedrops, and 2 eyes required surgical intervention. One eye had a best spectacle-corrected visual acuity of less than 20/30 at last follow-up.

CONCLUSIONS

Focal LSCD can be a result of SCL wear, presenting with varying manifestations. SCL wearers should be monitored routinely and counseled on this possible complication. Early identification of focal LSCD in SCL wearers with subsequent cessation of wear may prevent the need for surgical intervention.