Iatrogenic limbal stem cell deficiency following drainage surgery for glaucoma

Case report: Medical treatment for limbal epithelial stem cell deficiency in patients treated for glaucoma

Limbal epithelial stem cell deficiency (LSCD) is an abnormal corneal epithelial lesion with several causes. The patient was diagnosed using fluorescein staining. Bullous keratopathy, multiple surgeries, and drug-related damage can cause LSCD in glaucoma patients. We evaluated the medical treatment course for LSCD in patients with glaucoma. We retrospectively reviewed the electronic medical records of patients diagnosed with LSCD and investigated their background, course of treatment, and classification stages of LSCD before and after treatment. The global consensus classification system (stages IA-C, IIA-B, and III) proposed by Deng et al. (Cornea 2020) was used. Seven patients (two males) and eight eyes were studied. The median age of the patients was 82 years, and the mean duration of glaucoma treatment was 8 years. The patients had open-angle glaucoma (four eyes), exfoliation glaucoma (one eye), neovascular glaucoma (one eye), normal tension glaucoma (one eye), and uveitic glaucoma (one eye). Stage classifications at diagnosis were stage IA in four eyes and stages IC, IIA, IIB, and III in one eye each. All treatments were carried out with dry eye drops, steroid eye drops, and antibiotics. The mean duration of treatment was 1.4 years. The classifications at the time of the final visit were normal corneal epithelium (three eyes), stage IA (two eyes), IIA (one eye), and III (two eyes). Three eyes (37%) improved by more than one stage and one eye deteriorated by more than one stage. LSCD is long-lasting and difficult to treat in a short period; thus, it requires careful medical attention.

Ocular Surface Disease in Glaucoma Patients

PURPOSE

To review the most recent studies in the literature regarding the ocular surface in glaucoma patients and treatment options aimed to reduce ocular surface disease in this population.

METHODS

We performed a literature search in the electronic databases of PubMed CENT RAL, Google Scholar, EMBASE the Register of Controlled Trials, and Ovid MEDLINE using the following terms: "ocular surface", "dry eye", "glaucoma", "selective laser trabeculoplasty", "glaucoma surgery", "preservatives", "preservative free", "ocular surface disease index", "tear break up time", "MMP-9" and "conjunctival hyperemia".

RESULTS

Over the last several years, several studies have demonstrated the changes to the ocular surface in the setting of glaucoma, the best tests for markers of dry eye, and how management can be altered to help address ocular surface disease routinely or in preparation for glaucoma surgery.

CONCLUSION

Ocular surface disease in the glaucoma patient population is widely recognized. It should be addressed to maximize patient compliance and quality of life.

Autologous Serum Eye Drops in the Management of Limbal Stem Cell Deficiency Associated With Glaucoma Surgery

PURPOSE

To evaluate safety and efficacy of autologous serum eye drops (AS) in the treatment of limbal stem cell deficiency (LSCD) associated with glaucoma surgery.

METHODS

Retrospective case series of eyes with glaucoma surgery-induced LSCD treated with AS. Diagnosis of LSCD was confirmed by anterior segment optical coherence tomography, in vivo confocal microscopy, and/or impression cytology. Limbal stem cell deficiency severity was staged using a clinical scoring system (2-10 points). Outcome measures were changes (≥2 points) of the LSCD score and best-corrected visual acuity (BCVA) from the baseline to the last follow-up.

RESULTS

Thirteen eyes of 12 consecutive patients treated with 50% AS for at least 3 months were included. The mean age was 78.9±7.5 years and the mean duration of AS use was 20.9±16.8 months. Indications of AS included LSCD progression in eight eyes (61.5%) and visual axis threatening in five eyes (38.5%). The mean LSCD score at baseline (6.7±1.6) was similar to that at last follow-up (6.5±2.2, P =0.625). Two eyes (15.4%) showed improvement, nine eyes (69.2%) were stable, and two eyes (15.4%) worsened. The mean baseline BCVA (0.89±0.64 logMAR) was similar to the mean final BCVA (1.05±0.63 logMAR, P =0.173). There were no serious adverse complications related to AS.

CONCLUSION

AS appears to be well tolerated and may stabilize the progression of LSCD with limited effects. A larger study is necessary to confirm the findings.

Profile of biological characterizations and clinical application of corneal stem/progenitor cells

Corneal stem/progenitor cells are typical adult stem/progenitor cells. The human cornea covers the front of the eyeball, which protects the eye from the outside environment while allowing vision. The location and function demand the cornea to maintain its transparency and to continuously renew its epithelial surface by replacing injured or aged cells through a rapid turnover process in which corneal stem/progenitor cells play an important role. Corneal stem/progenitor cells include mainly corneal epithelial stem cells, corneal endothelial cell progenitors and corneal stromal stem cells. Since the discovery of corneal epithelial stem cells (also known as limbal stem cells) in 1971, an increasing number of markers for corneal stem/progenitor cells have been proposed, but there is no consensus regarding the definitive markers for them. Therefore, the identification, isolation and cultivation of these cells remain challenging without a unified approach. In this review, we systematically introduce the profile of biological characterizations, such as anatomy, characteristics, isolation, cultivation and molecular markers, and clinical applications of the three categories of corneal stem/progenitor cells.

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.

Referral Patterns of Patients with Limbal Stem Cell Deficiency to a Specialized Tertiary Center in the United Kingdom

INTRODUCTION

Limbal stem cell deficiency (LSCD) is a potentially blinding disease; hence, referral to a specialist service is becoming increasingly common. Our aim was to investigate the referral patterns and associated details.

METHODS

We conducted an audit of 100 consecutive patients with LSCD who were referred to our service from 2011 to 2018. Patient demographics, geographical location, cause of LSCD, coexisting ocular diseases, best corrected visual acuity (BCVA), and extent of LSCD were recorded. The following two subgroups were further analyzed: (1) burns and (2) other causes of LSCD.

RESULTS

Out of the 100 patients (138 eyes), 70% were male, with a mean age of 45 years (SD 19). LSCD was unilateral in 62% of the cases. The most common ocular comorbidity was glaucoma, in 21 patients (33 eyes). Burns were the most frequent cause of referral (61%). The mean BCVA of the involved eye was 1.22 (SD 0.8) LogMAR, and total LSCD was present in 75 eyes (54%). There were statistically significant age, gender and eye-involved differences between the burns group and other causes group, mean 39 (SD 17) and 53 (SD 19) years (p < 0.001); 85% were men versus 48.7%, (p = 0.001); and 82% were unilateral versus 31% (p < 0.001), respectively.

CONCLUSIONS

LSCD was more common in men and usually unilateral. Overall, the main cause of LSCD was burns. There were significant differences between the burns group and other causes of LSCD group in terms of age, gender and unilateral involvement that may help to guide management decisions.

Corneal epithelium and limbal region alterations due to glaucoma medications evaluated by anterior segment optic coherence tomography: a case-control study

AIM

To investigate the corneal epithelial and limbal epithelial alterations in patients under topical glaucoma treatment using anterior segment-OCT (AS-OCT) and to determine the changes of the limbal region due to the preservatives and glaucoma drugs, that can progress to limbal stem cell deficiency (LSCD). Limbal thickness was measured by AS-OCT to evaluate limbal cell deficiency.

METHODS

Forty-seven patients using topical medication for glaucoma, and 48 control subjects were enrolled in this matched case-control study. The patients were divided into four groups according to the treatment regimens. Group 1: One-drug regimen, Group 2: Two-drug regimen, Group 3: Three-drug regimen, Group 4: Four-drug regimen For the ocular surface evaluation; tear break-up time with standard fluorescein sodium sterile strip application, Schirmer test-I, Ocular Surface Disease Index Questionnaire, and AS-OCT were performed.

RESULTS

A total of 95 subjects were included: 47 eyes of 47 patients with glaucoma medication and 48 eyes of 48 healthy subjects. There was a statistically significant difference between patients and controls according to BUT, SCH, and OSDI (p < 0.001). The mean central corneal epithelium thickness was 48.5 ± 5.3 in patients and 54.5 ± 5.9 in controls (p < 0.001). The mean central total corneal thickness was 529.2 ± 41.2 in patients and 536 ± 35.3 in controls (p = 0.335). The mean limbal epithelium thickness was 64.1 ± 9.1 in patients and 76 ± 11.5 in controls (p < 0.001).

CONCLUSION

Using at least one glaucoma drug caused limbal area injury, changed ocular surface measurements, and significantly reduced the limbal epithelial thickness where the stem cells reside. The limbal epithelial thickness measurement by AS-OCT seems to be an innovative, non-invasive, and promising technique for detecting and staging corneal damage in topical glaucoma therapy.

Limbal Stem Cell Deficiency After Glaucoma Surgery

PURPOSE

To characterize the clinical presentation of limbal stem cell deficiency (LSCD) associated with glaucoma surgeries.

METHODS

This is a retrospective cross-sectional study of patients with LSCD and glaucoma who presented to the Stein Eye Institute at the University of California, Los Angeles, between 2009 and 2018. Patients who underwent trabeculectomy and/or aqueous shunt surgery were included. The severity of LSCD was staged using global consensus guidelines and a clinical scoring system, and basal epithelial cell density was measured by in vivo confocal microscopy. Anatomic locations of glaucoma and non-glaucoma surgeries, locations of LSCD, and severity of LSCD were compared.

RESULTS

Fifty-one eyes of 41 patients with LSCD associated with glaucoma surgery were included in this study. LSCD in these patients uniquely featured sectoral replacement of corneal epithelium by conjunctival epithelium, without corneal neovascularization or pannus. The sites of glaucoma surgery strongly correlated with the locations of LSCD (P = 0.002). There was a trend toward increased severity of LSCD in eyes with 2 or more glaucoma surgeries as compared to eyes with 1 glaucoma surgery, although the difference did not reach statistical significance (P = 0.3). Use of topical glaucoma medications correlated with LSCD severity, while the impact of antimetabolites did not reach statistical significance. The location of glaucoma drainage surgery is correlated with the location of LSCD.

CONCLUSIONS

LSCD associated with glaucoma surgery has clinical features distinct from LSCD resulting from other etiologies. Further study is required to delineate the full impact of glaucoma surgery on limbal stem cell function and survival.

Iatrogenic corneal diseases or conditions

Any prescribed or self-administered therapy carries inherent risks of secondary adverse events. While the volume of treatments being administered through healthcare systems has been increasing, scientific advancements in our understanding of the mechanisms of pharmaceutical side effects and complications from procedures now allow us to reduce the risk of non-intentional damage to ocular health. This review summarizes the most common and leading causes of iatrogenic visual impairment, corneal diseases, and conditions that present in a general ophthalmologic practice, including a comprehensive analysis of their pathophysiology and recommendations for management and prophylaxis.Iatrogenic corneal diseases and conditions can arise from topical drugs, contact lens use, eye surgeries and procedures, systemic drugs, non-ophthalmological events, and cosmetic procedures. Topical and systemic drugs may disturb tear film homeostasis or result in ocular surface deposits. The use of ill-fitted contact lenses can trigger eye discomfort and poor hygiene conditions that can predispose to severe infections. Procedures to the eye may result in a variety of anatomical and functional complications that ophthalmologists should be aware of how to avoid or at least be prepared to manage if they occur. Even non-ophthalmological events such as non-invasive ventilation, radiation therapies and, immune-based conditions, or cosmetic procedures such as eyelash growth and fillers, can result in unwanted damage to the ocular surface.

Anterior Segment Optical Coherence Tomographic Angiography Assessment of Acute Chemical Injury

PURPOSE

To compare routine clinical examination with optical coherence tomography angiography (OCTA) for the assessment of limbal conjunctival ischemia following a chemical burn.

SETTING

Validity analysis.

METHODS

We assessed 10 participants (15 eyes) with an acute chemical injury. Clinical photographs were used to determine the extent of any limbal conjunctival epithelial defect and ischemia. These were compared with the extent of limbal ischemia identified on OCTA images of the ocular surface. Quantitative and longitudinal analysis using the OCTA software were also performed. Correlations with visual outcome were sought using clinical and OCTA-derived variables.

RESULTS

The extent of clinically determined limbal ischemia was less than that identified with OCTA (2.3±3.6 clock hours vs 5.1±4.2 clock hours, P = .003), which in turn was less than the size of limbal conjunctival epithelial defect (7.3±5.1 clock hours, P = .03). Longitudinal OCTA analysis showed that mean vessel area increased by 0.2%±0.1% during the study, corresponding to a rate of vascular recovery of 0.9 mm²/d. Significant correlations were found between visual outcome at 3 months and limbal conjunctival fluorescein staining (r = 0.67, P = .006), and limbal conjunctival ischemia on OCTA (r = 0.76, P = .001).

CONCLUSIONS

OCTA can objectively identify and monitor the recovery of limbal ischemia following an acute ocular chemical injury. OCTA confirms that limbal ischemia is usually more extensive than is suggested by clinical examination, and the former is highly correlated with visual outcome. OCTA therefore is a useful tool in the management of ocular chemical injury.

Peritomy-sparing scleral buckle

Purpose

To introduce a modified technique for encircling circumferential scleral buckling without peritomy thorough a small conjunctival opening for the repair of uncomplicated rhegmatogenous retinal detachment (RD).

Methods

This technique was performed in 10 eyes of 10 patients with primary rhegmatogenous RD who underwent encircling circumferential scleral buckling without peritomy. Transconjunctival traction sutures were placed in four rectus muscles. After transconjunctival location of the retinal break, a 5- to 6-mm radial conjunctival incision was performed in 4 quadrants without cutting the limbal conjunctiva–Tenon's capsule. A 240-silicone band in scleral belt loops was used for an encircling circumferential buckle. After drainage and cryopexy, SF6 was used for tamponade. The incision was closed via layered closure only ocassionally.

Results

Primary attachment success of 100% was achieved by single procedure. The intraoperative and postoperative complications observed included subconjunctival hemorrhage observed in 5 (50%) of eyes. These disappeared in the postoperative period.

Conclusions

Minimal conjunctival incision in scleral buckle without peritomy can achieve excellent anatomical success in patients with rhegmatogenous RD without distorting ocular surface anatomy. This is the first description of technique preserving corneal limbus anatomy that could convert buckling surgery to more attractive option for retina surgeons.