Cataract surgery in patients with multiple corneal «segmentations» after radial keratotomy
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2025-07-16 |
| Journal | POINT OF VIEW EAST – WEST |
| Authors | A.A. Petukhova, S.Y. Kopaev, A.A. Troshina, Y.V. Grigoryeva |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”This case report details the engineering challenges and successful surgical tactics for cataract removal in patients with corneas severely compromised by prior Radial Keratotomy (RK), a procedure resulting in multiple linear scars (segmentations).
- Core Challenge: Extreme corneal irregularity and instability due to numerous RK scars (up to 32 incisions), leading to highly inaccurate standard IOL (Intraocular Lens) power calculations and elevated surgical risk (scar dehiscence, endothelial damage).
- Advanced Diagnostics: Utilization of Scheimpflug topography (Pentacam-HR) and Anterior Segment OCT for detailed, high-resolution assessment of scar integrity, corneal thickness, and profile deformation (central flattening, peripheral steepening).
- IOL Calculation Optimization: Employing the Barrett True K formula across multiple platforms, with a critical 0.5 Diopter offset toward slight myopia to counteract the high risk of post-operative hyperopic shift common in post-RK eyes.
- Precision Surgical Execution (FLACS): Femtosecond Laser-Assisted Cataract Surgery (FLACS) using the CATALYS platform was implemented for standardized, complete capsulorhexis and phacofragmentation.
- Mechanical Stress Mitigation: FLACS significantly reduced mechanical stress on the zonular fibers and minimized the required phacoemulsification energy, crucial for eyes with high axial length and compromised corneal structure.
- Process Control: Phacoemulsification was performed using the Centurion system at a controlled low Intraocular Pressure (IOP) of 35 mm Hg to maintain anterior chamber stability and protect the corneal endothelium.
- Outcome: Successful restoration of functional visual acuity (0.5 decimal) matching the retinal potential, confirming the efficacy of the personalized diagnostic and surgical protocol.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| RK Incision Count (OD/OS) | 32 / 16 | Count | Pre-operative corneal segmentation density. |
| Axial Length (OD/OS) | 28.95 / 26.40 | mm | High myopia status. |
| Endothelial Cell Density (OD) | 2289 | cells/mm2 | Pre-operative assessment of corneal health. |
| Endothelial Cell Density (OS) | 2460 | cells/mm2 | Pre-operative assessment of corneal health. |
| Central Corneal Thickness (OS) | 555 | µm | Thickness at the apex (Pentacam data). |
| Thinnest Location (OS) | 534 | µm | Critical structural integrity metric. |
| Pre-op Keratometry K1 (OD/OS) | 30.84 / 31.54 | Diopters | Highly flattened central cornea. |
| Pre-op Keratometry K2 (OD/OS) | 31.56 / 32.56 | Diopters | Highly flattened central cornea. |
| Phacoemulsification IOP Setting | 35 | mm Hg | Low IOP setting used on Centurion system for stability. |
| IOL Power Implanted (OD) | +23.0 | Diopters | Alcon SA60AT, 0.5 D offset applied. |
| IOL Power Implanted (OS) | +27.5 | Diopters | Alcon SA60AT, 0.5 D offset applied. |
| Post-op Visual Acuity (3 months, OD/OS) | 0.5 / 0.5 | Decimal | Achieved functional outcome. |
Key Methodologies
Section titled “Key Methodologies”- Comprehensive Biometric and Topographic Analysis: Performed using IOL-Master and Scheimpflug topography (Pentacam-HR) to generate “4 refractive maps” detailing corneal power, elevation, and thickness profiles.
- Corneal Scar Integrity Assessment: Anterior Segment Optical Coherence Tomography (OCT) was utilized to evaluate the depth, character, and structural stability of the numerous keratotomy scars, particularly in the superior quadrants.
- IOL Power Calculation Protocol: The Barrett True K formula was used as the primary calculation method, cross-referenced with ASCRS calculator data. A deliberate 0.5 Diopter hyperopic offset was avoided by selecting a slightly stronger IOL to mitigate the risk of post-RK hyperopic shift.
- Femtosecond Laser Pre-treatment (FLACS): The CATALYS Johnson & Johnson platform executed precise, standardized steps:
- Complete 360° capsulorhexis without residual tissue bridges.
- Pre-fragmentation of the cataractous lens nucleus.
- Phacoemulsification Process Control: Cataract removal was performed using the Centurion system, maintaining a controlled low Intraocular Pressure (IOP) of 35 mm Hg to minimize mechanical stress on the compromised cornea and zonular apparatus.
- Surgical Incision Management: The main limbal incision was strategically placed either between existing keratotomy scars or by intersecting a confirmed stable scar, based on pre-operative OCT data, avoiding the need for complex scleral tunnel construction.
Commercial Applications
Section titled “Commercial Applications”- Precision Ophthalmic Surgery Systems: Development and refinement of Femtosecond Laser-Assisted Cataract Surgery (FLACS) platforms (e.g., CATALYS) optimized for structurally compromised eyes.
- Advanced Ophthalmic Diagnostics: Manufacturing and integration of high-resolution corneal imaging devices (Scheimpflug topography, OCT) essential for post-refractive surgical planning.
- Intraocular Lens (IOL) Technology: Design and production of specialized IOLs and calculation software (e.g., Barrett True K) that accurately predict refractive outcomes despite highly irregular corneal surfaces.
- Surgical Process Control Equipment: Phacoemulsification systems (e.g., Centurion) featuring advanced fluidics and low-pressure control mechanisms to ensure safety during high-risk procedures.
- Biomaterial Integrity Assessment: Non-invasive methods for quantifying the mechanical stability and healing status of corneal incisions and scars.
View Original Abstract
Abstract Incisional keratotomy was originally used to correct astigmatism, including keratoconus. Anterior radial keratotomy (RK) has gained popularity since its modification by S.N. Fedorov. Surgical technique varied among surgeons; most of them agreed that a diamond blade was the preferred instrument, but they didn’t come to this opinion immediately and for a long time RK was performed using a metal blade. In addition, opinions differed regarding the number of incisions, their direction, and the choice of diameter of the optimal safe optical zone. These parameters determined the refractive outcome after RK. Today, the type of scars and their localization play a very important role in cataract surgery in such patients, since the necessity of optimization of intraocular lens (IOL) calculations and techniques of phacoemulsification is r equired. Keywords: radial keratotomy, surgical technique, optical zone, phacoemulsification