Combined ethylenediaminetetraacetic acid chelation, phototherapeutic keratectomy and amniotic membrane transplantation for treatment of band keratopathy

Modified Transepithelial Phototherapeutic Keratectomy for Band Keratopathy

Objectives: To report the outcomes of novel modified transepithelial phototherapeutic keratectomy (PTK) in treating band keratopathy (BK). Methods: A retrospective analysis was performed on patients who underwent PTK for BK at the Sussex Eye Laser Clinic, Nuffield Health, Brighton. Patients with BK obscuring the visual axis, affecting visual acuity, or causing discomfort were considered for PTK. All the patients underwent preoperative evaluation, including preoperative corneal topography and optical coherence tomography. Modified transepithelial PTK was performed without using EDTA for chelation or alcohol for epithelium debridement. Patients were followed up for one week and then every two weeks after that until two months. Preoperative and postoperative best corrected visual acuities (BCVA) were compared using a paired t-test. Results: We studied 15 eyes of nine patients undergoing novel PTK for BK. The mean age was 80 ± 5.73 years. The mean pre-treatment visual acuity was 0.68 ± 0.17 logMAR (range: 0.6 logMAR to 1 logMAR) and improved to 0.22 ± 0.09 logMAR (p < 0.05), ranging from 0.18 to 0.48 logMAR at two months following PTK. None of the patients complained of ocular discomfort following the procedure. A repeat procedure was not required for any of these patients. Conclusions: Modified transepithelial PTK is an effective procedure for improving visual outcomes in patients with band keratopathy and should be considered for the treatment of band keratopathy.

Dissolution of presumed calcareous corneal degeneration with 13.8% ethylenediaminetetraacetic acid solution in 17 dogs

PURPOSE

To describe a novel treatment for dissolving calcareous corneal degeneration (CCD)-associated mineral in 17 dogs with 13.8% ethylenediaminetetraacetic acid (EDTA) solution.

METHODS

Cases seen between 2021 and 2023 were reviewed. Seventeen dogs with CCD associated with corneal ulcerations were treated with a mineral dissolution procedure using 13.8% EDTA solution. A diamond burr keratotomy (DBK) was subsequently performed in some cases when residual mineralization remained present.

RESULTS

Of the 19 eyes (17 dogs) included in the study, 10 eyes (8 dogs) required a DBK procedure. One eye (one dog) required a repeat procedure 26 weeks following the initial procedure and two eyes (one dog) required a repeat procedure 24 and 37 weeks following initial treatment in the left and right eye, respectively. Mean follow-up time to last recheck for eyes not requiring a second chelation procedure was 20.4 weeks (range, 10-47 weeks). At the last follow-up examination for all 17 dogs, the CCD resolved in 26.3%, improved in 57.9%, and recurred in 15.8% of eyes. Complications occurred in two eyes (two dogs) and included an infected stromal ulcer at 2-week recheck and the creation of a 40% depth stromal defect immediately following debridement. Both complications were successfully addressed with medical management.

CONCLUSIONS

The utilization of 13.8% EDTA solution appears to be an effective and safe means of treating lesions associated with CCD.

Amniotic membrane transplantation: structural and biological properties, tissue preparation, application and clinical indications

The amniotic membrane is a single epithelial layer of the placenta. It has anti-inflammatory, anti-scarring, anti-angiogenic and possibly bactericidal properties. The basement membrane of the amniotic membrane acts as a substrate to encourage healing and re-epithelialisation. It has been used in many ocular surface diseases including persistent epithelial defects (corneal or conjunctival), chemical or thermal burns, limbal stem cell deficiency, cicatrising conjunctivitis, ocular graft versus host disease, microbial keratitis, corneal perforation, bullous keratopathy, dry eye disease, corneal haze following refractive surgery and cross-linking, band keratopathy, ocular surface neoplasia, pterygium surgery, and ligneous conjunctivitis. This review provides an up-to-date overview of amniotic membrane transplantation including the structural and biological properties, preparation and application, clinical indications, and commercially available products.

Comparative Analysis of Alternative Calcium Chelators for the Treatment of Calcific Band Keratopathy

PURPOSE

In this study, we compared clinically relevant biochemical properties of each chelator for pH, osmolarity, and calcium chelation potential.

METHODS

In total, 0.2 M K 2 EDTA and K 3 EDTA (BD vacutainer tubes by Becton, Dickinson and Company) and Na 2 EDTA (Sigma Aldrich) solutions were made. The pH of each solution was measured (Mettler Toledo pH meter), and the theoretical osmolarity was calculated. Next, we determined the calcium chelation potential of each EDTA salt by titrating it with 10 μmol of calcium hydroxyapatite or CaCl 2 containing Patton-Reeder colorimetric indicator. Statistical significance was analyzed using analysis of variance.

RESULTS

The 0.2 M solutions of Na 2 EDTA, K 2 EDTA, and K 3 EDTA have pH values of 4.43, 5.71, and 9.191 and theoretical osmolarities of 600, 600, and 800 mOsm/L, respectively. Calcium chelation ability was similar among all 3 solutions: 0.94 to 0.98 mol of EDTA was needed to fully chelate 1 mol calcium ions of CaCl 2 ( P = 0.296), 0.100 to 0.108 mol of EDTA for 1 mol calcium ions of the hydroxyapatite aqueous suspension ( P = 0.296), and 0.992 to 0.996 mol for 1 mol calcium ions of hydroxyapatite in acidic solution ( P = 0.178). Compared with the clinical standard of 3% (30 mg/mL) Na 2 EDTA, approximately 3.3% (33 mg/mL) K 2 EDTA and 3.6% (36 mg/mL) K 3 EDTA are needed to chelate an equivalent amount of calcium.

CONCLUSIONS

In this article, we provide clinically relevant biochemical properties of 2 alternatives to Na 2 EDTA and demonstrate comparable calcium chelation ability among all 3 solutions. In situations where sterile sources of Na 2 EDTA are unavailable, potassium EDTA may provide a convenient and equally effective method of treatment for band keratopathy.

Topical Ethylenediaminetetraacetic acid (EDTA) administration following corneal diamond burr keratotomy for calcareous corneal degeneration in canines

OBJECTIVE

To evaluate the outcomes of canine patients diagnosed with corneal ulceration associated with presumed calcareous corneal degeneration (CCD) that were treated with diamond burr keratotomy (DBK) and ongoing postoperative topical 3% or 4% Ethylenediaminetetraacetic acid (EDTA).

PROCEDURES

Retrospective assessment of CCD cases treated with ongoing topical EDTA following DBK between 2011 and 2020 at Veterinary Ophthalmic Referrals. Descriptive statistics of the study population were assessed, and a survival analysis was performed using R statistical software.

RESULTS

A total of 51 eyes from 41 dogs were assessed, with small terrier breeds overrepresented (27/41, 65.9%). Median age of dogs at the time of diagnosis was 14.3 years (range 8-17.2 years). Following DBK, the median time to commencement of topical EDTA was 11 days (range 0-28 days). Cases were followed for a median duration of 216 days (range 42-1379 days). Corneal ulceration recurred in 7/51 (13.7%) eyes at a median duration of 80 days (range 63-156 days). The probability of recurrence of corneal ulceration associated with CCD at 12 months was 15.6% (95% CI: 4.1-25.7%). A second DBK procedure followed by ongoing topical EDTA was performed in 4/7 (57.1%) of the recurred eyes. These retreated eyes had no further recurrence recorded and a median follow-up time of 401 days (range 120-858 days).

CONCLUSION

Ongoing topical EDTA following DBK is an effective adjunct treatment method for CCD with reduced rates of recurrence of CCD-associated corneal ulceration when compared to published rates of recurrence when treated with DBK alone.

CHELATION OF BAND KERATOPATHY IN LONG-TERM MONITORING

AIM

To report the clinical results of chelation of band keratopathy in long-term follow-up.

MATERIAL AND METHODS

The long-term results of 5 patients (5 eyes) with symptomatic band keratopathy with a follow-up period of at least 6 months, in whom 2% EDTA was chelated on the affected eye in the study period from April 2018 to March 2021, were retrospectively evaluated. The follow-up period was 9-37 months.

RESULTS

In all patients, there was a significant improvement in the local findings and an increase in the transparency of the cornea. The effect of therapy was verified on a color photograph of the anterior segment and on AS-OCT by the disappearance of subepithelial hyperreflective foci and accompanying optical shadows. Postoperatively, this enabled a more detailed visualization of the deeper layers of the cornea and other structures of the anterior segment. In a patient with the potential to improve vision, it was also possible to significantly improve visual functions. In the other three patients with pain in the affected eye, the pain subsided, and they also benefited cosmetically from the operation.

CONCLUSION

Based on our experience and previously published reports, EDTA corneal chelation is able to causally resolve the pathology and improve vision in eyes with visual potential. At the same time, it reduces discomfort and has an analgesic effect in long-term irritated eyes. The operation is also suitable for amaurotic, cosmetically unsightly bulbs, as a successful intervention preserving the eye and improving the appearance of such eyes leads to satisfaction and a subjective increase in the quality of life of the patients.

Phototherapeutic keratectomy: Indications, methods and decision making

Phototherapeutic keratectomy (PTK) involves treating anterior corneal lesions by superficial corneal ablation using an excimer laser (193 nm). Some of the commonly treated conditions include recurrent corneal erosions (RCE), corneal dystrophies, spheroidal degeneration, keratoconus, and corneal scars. We discuss various techniques of PTK including large area PTK, focal PTK, and multifocal PTK and alternatives to PTK. Masking agents like hyaluronate, methylcellulose, and dextran are recommended to help achieve a better outcome when ablating irregular corneal surfaces. Antifibrotic agents like mitomycin C reduce the chances of recurrence of the disease, apart from minimizing the postoperative scarring. Some of the complications include induced hyperopia and irregular astigmatism, haze, recurrence, and corneal thinning. However, earlier postoperative recovery, possibility of a repeat procedure, and ability to control the depth of ablation make PTK a promising, minimally invasive alternative to keratoplasty in cases with anterior corneal pathologies.

Ethylenediaminetetraacetic Acid Chelation in Herpes Zoster Ophthalmicus Is Associated With a High Rate of Corneal Melt and Perforation

PURPOSE

To examine the rate and risk factors for band keratopathy after herpes zoster ophthalmicus (HZO) and the outcomes of ethylenediaminetetraacetic acid (EDTA) treatment.

METHODS

This is a retrospective review of all subjects with HZO seen at Auckland District Health Board between January 2006 and December 2016.

RESULTS

A total of 869 subjects with HZO were included in the study. Median follow-up was 6.3 years (total 5504.4 patient-years). Band keratopathy developed in 13 subjects (1.5%). On multivariate analysis, older age at onset [hazard ratio (HR), 1.092; P = 0.034], intraocular pressure ≥30 mm Hg at presentation (HR, 5.548; P = 0.013), and number of recurrences (HR, 1.849; P < 0.001) were associated with increased risk for band keratopathy. Corneal melt occurred in 22 subjects (2.5%) during the follow-up period. On multivariate analysis, uveitis (HR, 8.618; P = 0.004) and disodium EDTA chelation (HR, 8.666; P < 0.001) were associated with increased risk for corneal melt. EDTA chelation was performed in 8 subjects. Corneal melt occurred after EDTA chelation in 4 subjects, and corneal perforation occurred in 2 subjects. One subject was eviscerated due to severe endophthalmitis after repeated corneal perforation and another required enucleation for recurrent corneal melt and microbial keratitis.

CONCLUSIONS

Band keratopathy is an uncommon complication of HZO. Treatment with EDTA chelation might be associated with a significant risk for severe complications in these eyes and should be approached with caution.

Excimer laser-assisted phototherapeutic keratectomies combined to EDTA chelation for the treatment of calcific band keratopathy

INTRODUCTION

Calcific band keratopathy (CBK) is a relatively common chronic corneal degeneration and various forms of treatment are mentioned in the literature.

CASES DESCRIPTION

Two patients (89 and 37 yo, respectively) affected by diffuse long-standing CBK in one eye and complaining of ocular pain, foreign body sensation and decreased visual acuity are reported. An ethylenediaminetetraacetic acid (EDTA) application on the ocular surface was performed associated with a customized no-touch transepithelial phototherapeutic corneal remodeling in one patient and a standard phototherapeutic keratectomy (PTK) in the second patient. Corneal transparency progressively improved in both cases since the early follow-up visits and the cornea became clear 2 weeks after surgery. In both cases, a significant reduction of ocular discomfort was reported.

CONCLUSIONS

Combining EDTA chelation and excimer laser-assisted PTK represents an useful treatment of band keratopathy even in challenging cases and may help regularize corneal surface and improve corneal clarity.

Transepithelial phototherapeutic keratectomy for the treatment of severe band keratopathy

PURPOSE

The goal of this study was to investigate the clinical outcomes of transepithelial phototherapeutic keratectomy (transepithelial PTK) for the treatment of severe band keratopathy.

METHODS

A consecutive series of severe band keratopathy cases treated with transepithelial PTK were retrospectively analysed between January 2018 and December 2019. Severe band keratopathy was defined as corneal plaques apparent in the obscuration of iris details. Patients' medical histories, preoperative and postoperative symptomatic relief, cosmesis, best-corrected visual acuity (BCVA), complications, and recurrences were analysed.

RESULTS

Seventeen eyes of 16 patients were included in the study, with a mean follow-up of 9.8 ± 5.2 months (3 to 19 months). The mean age of the patients was 15.8 ± 10.2 years (8 to 46 years). Symptoms were significantly or completely relieved in all patients (100%). The results of cosmesis were good in 14 eyes (82.4%). Among those eyes that had BCVA of hand motion or better preoperatively, seven eyes (100%) showed an improvement in BCVA postoperatively. There were no complications or recurrences associated with transepithelial PTK treatment during the follow-up period.

CONCLUSIONS

Transepithelial PTK is an effective treatment to eliminate corneal opacity and alleviate symptoms in patients with severe band keratopathy. This technique could be an alternative approach to managing severe band keratopathy.

Phototherapeutic keratectomy

Phototherapeutic keratectomy is an excimer laser-based surgical procedure widely performed by corneal surgeons for treating anterior corneal stromal pathologies. Phototherapeutic keratectomy helps by ablating the corneal stroma, thereby improving corneal clarity and smoothening the surface. Transient discomfort and induced hyperopia from corneal flattening are the immediate postoperative concerns. The long-term course is often marked by the recurrence of original corneal pathology and corneal haze formation. Phototherapeutic keratectomy, however, allows for repeat stromal ablation for managing recurrences, as the corneal thickness permits, without affecting the outcome of future keratoplasty. Adjunctive methods such as topical mitomycin-C may be additionally used to reduce recurrence rates. Also, various masking agents such as carboxymethyl cellulose, sodium hyaluronate, and dextran are used in eyes with irregular corneal surface to allow for uniform stromal ablation. Overall, phototherapeutic keratectomy has provided corneal surgeons an additional surgical tool, particularly those residing in developing nations where the availability of donor corneal tissue is an important limiting factor.

"Off-the-Shelf" K2-EDTA for Calcific Band Keratopathy

PURPOSE

To explore the effectiveness of "off-the-shelf" dipotassium-ethylenediaminetetraacetic acid (K2-EDTA) as an alternative to sodium EDTA as chelation therapy in removal of calcific band keratopathy (CBK).

METHODS

This study was a retrospective case series involving 4 patients with CBK who underwent superficial keratectomy and subsequent chelation therapy with K2-EDTA in a single center (Coastal Eye Clinic) by the same surgeon. Visual acuity and symptomatic relief were the main outcomes measured in our study.

RESULTS

All 4 participants in this study were female with an average age of 80.3 years. Three of the patients with reasonable baseline visual acuity experienced improved visual acuity at 1 month. The other patient with multiple ocular comorbidities and severely reduced visual potential reported symptomatic pain relief at 1-month follow-up after the intervention.

CONCLUSIONS

K2-EDTA seems to be an effective alternative to disodium EDTA in its ability to clear calcific plaques and restore visual function. Because of the logistical difficulties associated with acquiring disodium EDTA, and the relative abundance of K2-EDTA in health-care facilities, we believe that our findings warrant further investigation into its use as a more accessible and cost-effective chelating agent in CBK.

EDTA chelation for symptomatic band keratopathy: results and recurrence

PurposeTo identify causes of symptomatic band keratopathy, and assess the results and long-term recurrence rates following chelation with topical ethylene-diamine-tetra-acetic acid (EDTA).Patients and methodsA retrospective review of surgical logbooks identified patients managed by EDTA chelation for symptomatic band keratopathy from 2009 to 2015.ResultsWe identified 108 cases; 89 case notes were available for analysis. Most cases of band keratopathy were idiopathic (36%). The most commonly identified underlying diagnosis was long-term topical glaucoma therapy (27%). Median presenting visual acuity was 6/18 (range 6/6-NPL) with the visual axis affected in 97.8% of cases. Treatment involved corneal epithelium removal, recurrent application of topical EDTA, and subsequent debridement. The mean duration of the operation was 20 min (range 10-45). Mean initial follow-up time was 40 days, and the visual axis was clear in 97.8%. Visual acuity was maintained or improved in 79.8%, with 13.5% improving by two lines or more. The mean length of follow-up was 581 days (median 374, maximum 2438). Twenty-five eyes (28.1%) showed localised recurrence of calcium with a mean time of 546 days (median 374), but only four cases required repeat EDTA chelation. The median time between operations was 430 days. Thirty-two per cent of the recurrence cases were associated with hypotony or chronic presence of silicone oil.ConclusionsChelation of calcium with topical EDTA is a safe and effective treatment for band keratopathy. Visual acuity improves in most eyes and while the rate of recurrence is moderate, the need for retreatment is low (4.5% overall).

Comparison of corneal degeneration and calcific band keratopathy from 2000 to 2013 in 69 horses

OBJECTIVE

To compare signalment, presentation, treatment, and outcome in horses diagnosed with corneal degeneration (CD) or calcific band keratopathy (CBK) at a referral hospital.

ANIMALS STUDIED

Sixty-nine horses (87 eyes) diagnosed with either CD or CBK.

PROCEDURES

Medical records of horses diagnosed with CD or CBK at the University of California-Davis Veterinary Medical Teaching Hospital (UCD-VMTH) between 2000 and 2013 were reviewed. Signalment, concurrent ophthalmic diagnoses, previous therapies, diagnostic tests, systemic diagnoses, treatment, follow-up, and outcomes were compared between horses diagnosed with CD or CBK. Age, breed, and gender were compared between the CD/CBK and UCD-VMTH populations.

RESULTS

Thirty-three horses (42 eyes) and 36 horses (45 eyes) were diagnosed with CD and CBK, respectively. Horses with CD or CBK were significantly older (P < 0.001) than the UCD-VMTH population with a median age of 16 or 18 years, respectively. Appaloosas were significantly overrepresented in the CD/CBK population (33%) in comparison with the UCD-VMTH population (1.8%, P < 0.001). Equine recurrent uveitis was concurrently diagnosed in 67% and 84% of horses with CD or CBK, respectively. Pituitary pars intermedia dysfunction (PPID) was diagnosed significantly less often in horses with CD vs. CBK (P = 0.03). Chemical chelation with ethylenediaminetetraacetic acid was performed significantly less frequently in horses diagnosed with CD (7.1%) vs. CBK (31.1% of eyes) (P = 0.012).

CONCLUSIONS

Despite some differences, equine CD and CBK are relatively similar conditions and may represent a continuum of disease severity. Horses with PPID should be monitored closely for corneal disease including CBK.

Two percent ethylenediaminetetraacetic acid chelation treatment for band-shaped keratopathy, without blunt scratching after removal of the corneal epithelium

Background

The purpose of this study was to assess the effectiveness of 2% ethylenediaminetetraacetic acid (EDTA) for the treatment of band-shaped keratopathy.

Methods

We studied 24 eyes of 16 patients with band-shaped keratopathy who underwent EDTA chelation treatment from April 1, 2011 to December 31, 2012. We compared preoperative and 1 month postoperative logarithm of the minimum angle of resolution (logMAR) best corrected visual acuity, intraocular pressure, and corneal curvature radius (K1, horizontal meridian; K2, vertical meridian; Km, average of K1 and K2). The Mann-Whitney U-test was used to determine the significance of differences.

Results

There was a significant difference in preoperative and postoperative logMAR best corrected visual acuity (P=0.01). There were no significant differences in preoperative and postoperative intraocular pressure (P=0.24) or corneal curvature radius (K1, P=0.54; K2, P=0.49; Km, P=0.45).

Conclusion

After 2% EDTA chelation treatment, post-operative logMAR best corrected visual acuity improved significantly. Moreover, since there was no significant difference in corneal curvature radius, there was little influence on corneal surface form. We believe that the results of our 2% EDTA chelation treatment were comparable with results obtained with 3.75% EDTA chelation treatment in previous reports. Two percent EDTA chelation is an effective treatment for band-shaped keratopathy and a useful method for any institution.

Techniques, indications and complications of corneal debridement

The cornea is the most exposed surface of the eye and, as such, is vulnerable to external trauma and the risk of infection. Many corneal diseases alter shape, surface, and transparency and thus result in reduced vision. The external position of the cornea, however, lends itself to diagnostic and therapeutic maneuvers that are commonly performed and readily done in the clinic. More sophisticated techniques require the use of complex equipment such as excimer and femtosecond laser. Complications that develop from poor healing and/or secondary infection are best avoided with appropriate technique, antisepsis, and modification of wound healing. We review corneal debridement in the management of corneal disease.