A 75-year-old woman presented with visually significant cataracts and astigmatism. Her BSCVA was 20/40 OU with a manifest refraction of -0.50+1.50x75 OD and -1.0+1.25x65 OS. Slit lamp exam was notable for 3+ nuclear sclerosis and 2+ cortical spoking cataracts OU. Corneal topography showed regular astigmatism and was in good agreement with her previous refractions and the IOLMaster measurements.
The patient elected to undergo femtosecond laser assisted cataract surgery with implantation of toric IOLs. The laser procedure and subsequent phacoemulsification surgery on her right eye was uncomplicated, and she achieved an excellent outcome with 20/25 uncorrected visual acuity and 0.25 D of residual astigmatism. On her left eye, the laser treatment appeared to go smoothly but there was no visible bubble breakthrough during the capsulotomy. The OCT laser images for each eye are shown below:
Once the patient was brought to the operating room, the laser incisions OS were evaluated under the microscope and had the following appearance:
What error occurred?
Despite a flat dock and excellent OCT image for each eye, the LenSx laser did not correctly identify the anterior lens surface OS. This should have been recognized by the posterior placement of the horizontal purple lines as well as the depth values of these boundary markers, and then corrected by manually adjusting the purple incision boundaries.
Once in the operating room, it was immediately apparent that the anterior capsulotomy incision had occurred within the cataract creating an intralenticular ring of bubbles. There was no capsular incision. A manual capsulorhexis was performed, which was difficult in the region overlying the deep gas bubble because of poor contrast created by the altered silver-yellow reflex in this area. Staining the anterior capsule with Trypan blue would have greatly facilitated this step. The rest of the phacoemulsification procedure was uneventful, and the patient achieved an excellent outcome OS.
Discussion: This case highlights the importance of careful attention to detail. Familiarity can lead to complacency, and this is certainly true for common procedures, particularly automated ones, that we do frequently. It is rare for femtosecond laser devices to miscalculate incision locations when clear OCT images are obtained, but the surgeon must carefully check the accuracy of the data. I should have recognized the incorrect placement of the capsulotomy boundaries on the OCT image; however, I only gave it a cursory look and failed to identify the error. Fortunately, no harm resulted from this oversight, and no complications occurred during the subsequent surgery.