Six-Month Review of Nomogram for Nonpenetrating Femtosecond Laser Intrastromal Astigmatic Keratotomy During Femtosecond Laser-Assisted Cataract Surgery
Narrative Responses:
Purpose
To review the precision of a nomogram created for non-penetrating intrastromal astigmatic keratotomy using femtosecond laser during femtosecond laser assisted cataract surgery, with six month follow up data
Methods
52 eyes with corneal astigmatism underwent femtosecond laser-assisted cataract surgery with concurrent correction of astigmatism using paired symmetrical non-penetrating femtosecond laser intrastromal astigmatic keratotomy (FSAK) with in a single surgeon practice. FSAK was created simultaneously as laser capsulotomy and lens conditioning. FSAK incisions were created at between 20% to 80% depth and 30% to 80% depth from anterior corneal surface. All treatments were performed using an 8.0 mm optical zone with limbal centration. Follow up was performed 1 month and 6 months post-op. Using preoperative and postoperative topography and refractive data, a nomogram has been created using multiple regression analysis.
Results
The mean vector magnitude using nomogram v1 was 60% of intended and increased to 82% of intended with v2. The main source of residual cylinder was angle error, highlighting the importance of alignment. There was significant change between 1 month to 6 months post-op. The nomogram takes into account cylinder magnitude, age and angle of cylinder.
Conclusion
Catalys femtosecond laser non-penetrating intrastromal astigmatic keratotomy was able to reduce corneal cylinder during femtosecond laser-assisted cataract surgery. A nomogram has been created from our data to enhance predictability and accuracy of this treatment.