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Intra-operative complications are surgical complications that occur during the procedure itself.
Microkeratome-Related Complications
Patients should understand that the incidence of such complications is generally low. If one occurs, most surgeons will not proceed with the laser ablation at that time. Irregular cuts rarely lead to significant visual loss, and most of the time the surgeon will simply end the procedure that day and re-schedule the surgery a few months later.The incidence of all microkeratome-related complications reported in the literature range from 0.7% to 11.8%, but studies with the largest sample sizes demonstrate complication rates of 2.2% or less.1
| Study |
Complication Rate |
| CRS-USA LASIK Study (n=1800)2 |
1.2% |
| Emory Study (n=1,062)3 |
1.8% |
| Lin & Maloney (n=1,019)4 |
2.2% |
| Tham & Maloney(n=3998)5 |
0.7% |
As of April 1, 1998, the CRS-USA LASIK Study that considered 1,800 eyes noted two complications that arose during the procedures themselves resulting from the microkeratome: irregular cuts damaging the stromal bed (experienced by 0.03% of the patient population) and damage to the epithelium (0.47%). Two types of complications required patients to forgo treatment or return another day but did not cause loss of visual acuity: flaps were too small (0.38%) or too thin (0.38%). All of the aforementioned complications produced temporary effects. After 3 months, the visual results of the group experiencing Intra-operative complications were no different from the group who experienced no such complications.2
In January, 1999, the Emory group published a study on the results 1530 surgical procedures on 1062 eyes, and noted a 1.8% intra-operative complication rate. Seventeen eyes had to forgo treatment that day due to flap complications. Only 3 eyes (0.28%) lost 2 or more Snellen lines of best complications. Only 3 eyes (0.28%) lost 2 or more Snellen lines of best corrected visual acuity (BCVA).3 It should be noted that this study was based on procedures done well before the study's publication in 1999 and that the procedures used microkeratome and laser technology that has since been improved.
A 1999 study conducted by Doctors Robert Lin and Robert K. Maloney that considered 1,019 eyes for which a flap was created by means of a microkeratome noted a 2.2% intra-operative complication rate. However, no eyes suffered permanent decrease in visual acuity because of flap complications.4
A study of 3998 eyes noted a 0.68% flap complication rate - 27 eyes. Five had buttonholes (small tears or cuts), 2 had free caps (incisions that resulted in "flap" being cut off), 4 had irregular flaps, 7 had incomplete flaps, 9 had thin flaps and 5 had small flaps. Five eyes had more than one complication. Upon laying down the flap, twenty-six of the eyes recovered to within one line of best corrected visual acuity, and one eye lost two lines. Sixteen eyes had repeat LASIK, and all eyes that were retreated recovered to within one line of pre-operative best corrected visual acuity.5
Excimer Laser Ablation-Related Complications
Decentered ablations and central islands were considered in reports that appeared in 1999 or earlier. Incidence ranges from 1.2% for myopia (2 of 396 eyes)6 to 6.8% for early hyperopic astigmatic treatment (4 of 58 eyes).7 Eyes with decentered ablations and central islands generally required the use of rigid contact lenses for best vision correction.
As excimer laser technology and the surgical technique have been refined and advanced, these two complications are rarely seen today. Of the clinical studies submitted to the US FDA for approval of excimer laser systems, none reported decentered ablations or central islands.8
Recent advances in laser technology, called wavefront custom ablations, hold the promise of treating these conditions and alleviating the visual problems associated with them. For more information on custom ablations, please see our Technology section.
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