Marking the Toric IOL Axis: Comparative Study of Manual and Femtosecond Laser Method
Narrative Responses:
Purpose
To determine the correlation or the difference in the corneal marking of the toric IOL (intraocular lens) axis between femtosecond laser and manual method using a Mendez ring. To determine if the femtosecond laser offers an exact method of marking the toric iol axis.
Methods
Prospective, comparative, experimental study of 30 patients with the inclusion criteria: diagnosis of cataract, >18 years old, any gender, candidates to phacoemulsification and toric IOL implant. After making horizontal limbus marks (0-180 degrees) in the slit lamp, the alignment with femtosecond laser and corneal incisions for the toric IOL marks were made, then the femtosecond laser axis marks were compared with a mendez ring. After surgery, the toric iol axis was measured. The mean outcome measures (in degrees) were: difference between femtosecond laser marks and the Mendez ring marks, Axis of toric iol (at 1 day, 1 week, 1 month post-surgery).
Results
Average-age of the patients 65 + 12.09 years. Eighty percent of the femtolaser marks coincide exactly with the manual marks with a difference of 0 degrees. Twenty percent of the marks varied from 1 to 5 degrees. The average difference between the two methods was 1.33 + 2.13 degrees. T student test was not statistical significant (p= 0.85). Regresion analysis showed a high regression coefficient (r= 0.99, p<0.0001). Limit agreement analysis did not show any biass in measurement.
Conclusion
The femtosecond laser is an effective, reliable and safe method to mark the axis of a toric iol in cataract surgery. To get better results, it is important to be very careful in the preoperative 0 and 180 limbus marks in order to align correctly the femtosecond laser.