ARVO is the name of the research organization (Association for Research in Vision and Ophthalmology) which tends to do the most theoretical and basic science work in my field. So I was interested to read in Review of Ophthalmology about some interesting studies that were presented at that meeting regarding LASIK flaps.
A very interesting study out of New York City compared LASIK performed with the bladeless Intralase method to LASIK performed the older way using one of the most common bladed microkeratomes (Moria). The researchers performed 1000 consecutive cases of both bladeless and bladed LASIK and they found that use of the bladeless Intralase method significantly reduced their complication rate.
Bladeless versus bladed LASIK
In the bladeless Intralase group there were only 3 complications out of 1000 cases that occurred during the surgery itself. And 2 of those complications were able to be handled intraoperatively allowing the case to proceed normally.
In the bladed microkeratome group, however, there were 2x as many intraoperative complications (6 out of 1000). Worse yet, NONE of those 6 cases could be handled intraoperatively and the cases had to be aborted.
These numbers correspond to my general sense of the quality of the old style bladed microkeratomes. Although surgeons using these bladed instruments feel confident telling their patients that complications only occur less than 1% of the time, in reality, this can mean somewhere around 1 eye out of every 300 or so. And the type of complications generated by the bladed instruments was shown to be more severe in that they could not be handled at the time but required that the surgery be stopped.
But there’s more. The incidence of POST-operative flap related problems was even greater with the bladed microkeratomes compared to the blade free Intralase.
Complications from bladed LASIK could be serious
Using the bladeless Intralase, there were 2 cases of epithelial abrasions (superficial scratch on the eye surface) and 1 case of a flap buttonhole (central defect in the flap itself). The bladed microkeratome had 65 cases of epithelial abrasions.
That is not really surprising because the microkeratome requires that a physical blade vibrates back and forth over the surface of the eye so the tendency to scrape the surface is much greater. The microkeratome had 3x as many buttonholes too.
In addition, there were a large number of potentially significant postoperative flap problems that were not seen at all in the Intralase cases. These included 6 cases of flap striae which can indicate slippage or misplacement of the flap itself and might require adjustment. There were 22 cases of epithelial downgrowth which means the outer epithelium of the eye was carried under the flap by the vibrating blade where it is not supposed to be.
If this epithelial downgrowth grows, it can cause significant problems. The researchers also reported 12 cases of DLK (diffuse lamellar keratitis) in the bladed microkeratome group.
DLK is a significant inflammatory problem which can potentially cause damage to the cornea itself. In this case, it is probably a good assumption that physical contaminants which are transmitted by the blade itself (oils or metal fragments) are the culprit causing the inflammatory DLK condition. Using a laser beam which has no true physical presence is clearly superior to a blade in the sense that it is much gentler to the cornea and does not introduce foreign material as it works.
This ARVO study is just another example of high end research confirming the fact that the iLASIK and Intralase tools that we use are superior and safer than the old style microkeratomes still being used by so many other surgeons. A wise and educated patient should pay attention to this information.
In my mind, the era of bladed microkeratomes is long past and patients should only consider having LASIK by surgeons using the current bladeless Intralase technology.