Six-Month Review of Nomogram for Nonpenetrating Femtosecond Laser Intrastromal Astigmatic Keratotomy During Femtosecond Laser-Assisted Cataract Surgery

Saturday, April 26, 2014: 3:01 PM
Room 151B (Boston Convention and Exhibition Center)
Nicola M. Lau, MB, BSc(Hons), Moorfields Eye Hospital, London, United Kingdom
Julian D. Stevens, FRCOphth, Moorfields Eye Hospital, London, United Kingdom
Alexander C. Day, PhD, MRCOphth, Moorfields Eye Hospital, London, United Kingdom

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.