Evaluation of Femtosecond Laser Intrastromal Incision Location Using Optical Coherence Tomography

Abstract

Purpose Using optical coherence tomography (OCT) to evaluate the femtosecond laser intrastromal (IS) incisions made during cataract surgery to reduce corneal astigmatism. Design Retrospective case series. Subjects 77 eyes of 77 patients were included. Methods Paired IS incisions were created using the Catalys femtosecond laser (Abbott Medical Optics, Inc.). The planned IS incision parameters were 20% uncut anterior, 20% uncut posterior, midpoint depth of 50%, and 90° side cut angle. OCT scans were obtained three weeks or more postoperatively to assess these four parameters, and actual values were compared to intended values. Main Outcome Measures Percentages of uncut anterior and posterior tissue, midpoint depth, and degrees of side cut angle. Results The mean values were 17.2% ± 5.8% (range 7.2% to 36.9%) for uncut anterior, 32.5% ± 8.8% (range 6.0% to 57.9%) for uncut posterior, and 42.3% ± 6.6% (range 25.5% to 65.4%) for midpoint depth, which were all significantly different from the planned parameters (all P<0.05). The mean side cut angle was 88.5° ± 5.6° (range 71° to 114°) and was significantly different from the planned side cut angle of 90° (P<0.05). In 50 eyes that had paired IS incisions scanned by the OCT, there was no correlation between the paired incisions for midpoint depth and side cut angle (correlation coefficient r = −0.063 and −0.067, respectively, P>0.05). Conclusions The IS incision midpoint depth was significantly more anterior than the planned depth of 50%. The location of paired IS incisions in each eye were not correlated. Further improvements are needed to ensure the precise location of the IS incisions made with this device.

Outcome of astigmatism correction using femtosecond laser combined with cataract surgery: penetrating vs intrastromal incisions

“…In addition, in a previous study using OCT, we evaluated the location in the cornea of intrastromal CRIs made with the Catalys during cataract surgery. 24 The planned intrastromal incision parameters were 20% uncut anterior and 20% uncut posterior with a midpoint depth of 50%. We found that the intrastromal incision midpoint depth was significantly more anterior than the planned depth of 50%, and the locations of paired intrastromal incisions in each eye were not correlated.…”