Transepithelial phototherapeutic keratectomy for treatment-resistant recurrent corneal erosion syndrome
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-04-15 |
| Journal | Graefe s Archive for Clinical and Experimental Ophthalmology |
| Authors | Mukhtar Bizrah, Maheshver Shunmugam, Geoffrey Ching, Radhika Pooja Patel, Nizar Din |
| Institutions | Imperial College Healthcare NHS Trust, University of British Columbia |
| Citations | 3 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis study provides the largest long-term analysis of Transepithelial Phototherapeutic Keratectomy (TE-PTK) for Recurrent Corneal Erosion Syndrome (RCES) refractory to conventional treatments.
- High Efficacy for Refractory RCES: TE-PTK achieved complete resolution or significant improvement in symptoms for 96% of the 593 eyes studied, all of which had failed three or more conservative treatments.
- Low Recurrence Rate: The recurrence rate requiring repeat TE-PTK was exceptionally low at 1.1% (6 eyes), with a mean time to retreatment of 11.3 ± 14.9 months.
- Ablation Parameters: The standard protocol involved a total ablation depth of 65 ”m, comprising 50 ”m for epithelial removal and 15 ”m for subepithelial treatment, executed over a 9 mm treatment zone.
- Refractive Stability: A correction factor of +0.50 D was applied to the 65 ”m ablation depth in non-myopic eyes to achieve a neutral refractive outcome and minimize hyperopic shift.
- Safety Profile: The procedure demonstrated a good safety profile, with only 1.6% of eyes developing Grade 2 corneal haze, attributed partly to the prophylactic use of Mitomycin C (MMC) 0.02%.
- Long-Term Data: The mean post-operative follow-up period was extensive, averaging 60.5 months (range: 5-127 months), confirming long-term stability and efficacy.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Study Size (Eyes) | 593 | eyes | Retrospective case series |
| Mean Post-operative Follow-up | 60.5 | months | Long-term data collection |
| Total Ablation Depth (TE-PTK) | 65 | ”m | Epithelial (50 ”m) + Subepithelial (15 ”m) |
| Subepithelial Ablation Depth | 15 | ”m | Target depth for therapeutic effect |
| Total Treatment Zone Diameter | 9 | mm | Including ablation and transition zones |
| Hyperopic Shift Correction Factor | +0.50 | D | Applied for 65 ”m ablation in non-myopic eyes |
| Excimer Laser Tracking Rate | 1050 | Hz | Infrared eye tracker frequency |
| System Total Latency Time | 2.9 | ms | Eye tracking and laser response delay |
| Mitomycin C (MMC) Concentration | 0.02 | % | Used to minimize corneal haze |
| Mitomycin C Application Time | 30 | seconds | Post-ablation exposure duration |
| Pre-op CDVA (logMAR) | 0.15 ± 0.27 | logMAR | Corrected Distance Visual Acuity (Mean ± SD) |
| Post-op CDVA (logMAR) | 0.11 ± 0.17 | logMAR | Corrected Distance Visual Acuity (Mean ± SD) |
| Corneal Haze Incidence (Grade 2) | 1.6 | % | Safety outcome (No Grade 3 or greater reported) |
Key Methodologies
Section titled âKey MethodologiesâThe TE-PTK procedure utilized the SCHWIND Custom Ablation Manager and SCHWIND eye-tech solutions GmbH equipment, adhering to the following protocol:
- Pre-operative Biometrics: Topography and tomography (SCHWIND Sirius) were performed to measure pachymetry, elevation, curvature, and dioptric power over a 12 mm diameter.
- Anesthesia and Positioning: Topical anesthetics were instilled, and alignment was achieved using a 1050 Hz infrared eye tracker integrated with limbus, pupil, and torsional tracking.
- Ablation Centration: The ablation profile was centered on the corneal vertex, determined by topography, using 100% of the pupil offset value.
- Transepithelial Ablation: The excimer laser was operated in transepithelial mode, ablating 50 ”m for epithelial removal followed by 15 ”m of subepithelial treatment, totaling 65 ”m.
- Refractive Compensation: A correction factor of +0.50 D was applied for the 65 ”m ablation depth to achieve a neutral refractive outcome, except in myopic eyes.
- Haze Prophylaxis: Mitomycin C (MMC) 0.02% was applied to the ocular surface for 30 seconds immediately following the ablation.
- Post-Ablation Wash: The ocular surface was thoroughly washed with balanced salt solution for 30 seconds.
- Post-operative Dressing: A therapeutic bandage contact lens (AcuvueÂź 8.4 mm or 8.8 mm) was fitted, and patients were prescribed a regimen of Ciprofloxacin, Diclofenac, Fluorometholone, and preservative-free lubricants.
Commercial Applications
Section titled âCommercial ApplicationsâThe findings validate the long-term performance and safety of advanced excimer laser technology and specific surgical protocols for treating complex corneal surface disorders.
| Industry/Sector | Application/Product Focus | Relevance to TE-PTK Technology |
|---|---|---|
| Ophthalmic Laser Manufacturing | Excimer Laser Systems (e.g., SCHWIND) | Validation of proprietary transepithelial PTK modes and high-frequency eye tracking systems (1050 Hz) for precision corneal surface modification. |
| Medical Device Software | Customized Ablation Planning and Control | Development and commercialization of software algorithms that incorporate specific correction factors (+0.50 D for 65 ”m ablation) to manage induced hyperopic shift. |
| Advanced Ophthalmic Diagnostics | Corneal Imaging Systems (Topography/Tomography) | Requirement for high-resolution, wide-field (12 mm) diagnostic systems (e.g., Scheimpflug technology) to accurately map corneal surfaces and guide laser centration. |
| Drug Delivery and Biomaterials | Anti-Fibrotic Agents and Ocular Dressings | Standardization of Mitomycin C (0.02%) protocols for minimizing post-operative haze, influencing the design and marketing of related pharmaceutical delivery systems. |
| Refractive Surgery Training & Simulation | Surgical Protocol Standardization | Provides robust, long-term data supporting the adoption of TE-PTK as the preferred invasive treatment for RCES resistant to conservative management. |
View Original Abstract
Abstract Background To evaluate the efficacy and safety of trans-epithelial phototherapeutic keratectomy (TE-PTK) as a treatment for recurrent corneal erosion syndrome (RCES) in patients with symptoms refractory to conventional treatments. Methods All patients who received TE-PTK treatment for RCES had failed 3 or more conventional treatments and were reviewed, and if met criteria, approved by healthcare workers of the British Columbia public health authority (Medical Services Plan (MSP). A retrospective chart review and telephone survey were conducted at the Pacific Laser Eye Centre (PLEC). Exclusion criteria were ocular co-morbidities potentially affecting treatment efficacy. Results This study included 593 eyes of 555 patients (46.2% male; 50.9 ± 14.2 years old) who underwent TE-PTK. The leading identified causes of RCES were trauma (45.7%) and anterior basement membrane dystrophy (44.2%). The most common pre-PTK interventions were ocular lubricants (90.9%), hypertonic solutions (77.9%), and bandage contact lenses (50.9%). Thirty-six eyes had undergone surgical interventions such as stromal puncture, epithelial debridement, or diamond burr polishing. Post-PTK, 78% of patients did not require any subsequent therapies and 20% required ongoing drops. Six patients (1.1%) reported no symptom improvement and required repeat TE-PTK for ongoing RCES symptoms after initial TE-PTK. All 6 eyes were successfully retreated with TE-PTK (average time to retreatment was 11.3 ± 14.9 months). There was no significant difference in best corrected visual acuity pre- vs. post-operatively. The mean post-operative follow-up was 60.5 months (range: 5-127 months). Conclusion TE-PTK has a good efficacy and safety profile for treatment-resistant RCES. The third-party public health-reviewed nature of this study, the low recurrence rate of RCES, and the low PTK retreatment rate suggest that TE-PTK might be considered for wider use in the management of RCES.