Doctor's Answers (3)
In general, low suction LASIK femtosecond lasers have a lower tendency to cause blood clots on the white of eye. But they also have a higher chance of having suction loss which may complicate the surgery and even cause the abandonment of treatment and conversion to other treatment methods such as surface ablation techniques. These comparisons were proven by research done at the Singapore National Eye Centre a few years ago.
Having said that, the blood clots are generally superficial and rarely persist after a week or two.
To reduce the risk of having these blood clots, patients are advised to try and keep their eyes still during the suction phase of the femtosecond lasering. Looking straight at the target light of the laser and keeping a cool head throughout, and helping your surgeon by listening to and following instructions during the procedure will definitely contribute to a good result.
Earlier models of femtosecond lasers used in the creation of the LASIK flap grip the whites of the eye surrounding the cornea. This often leads to bruising in the same area which in the case of the eye appears bright red. Fortunately, these red patches do resolve in about 2 weeks without any serious long term complications.
Newer generations of femtosecond lasers now apply suction to the cornea itself which does not have any blood vessels and as a result, the incidence of subconjunctival hemorrhage is much lower. There really isn’t much that the patient can do to prevent the risk of sub-conjunctival hemorrhage as it pretty much depends on the type of femtosecond laser used.
The main strategy to aid in a swift recovery is to follow the post-operative instructions given by your eye surgeon on the usage of post-operative eyedrops and measures to avoid infection. Otherwise, the visual recovery in the case of LASIK or ReLEx SMILE is often quite rapid.
Hi Susanne In the first step of the LASIK procedure, a ‘flap’ is created using a femtosecond laser (or, in the past, a special blade called a microkeratome). During this step, the laser is ‘connected’/docked to the eye with a ring-like device that grips the white part of your eye.
You can watch an animation here:
There are many small blood vessels on this part of the eye, and sometimes the suction pressure providing the grip may cause some of the blood vessels to leak some blood, causing red patches after the LASIK.
We call this a subconjunctival haemorrhage, or SCH. The risk is somewhat higher if, during the procedure the docking process has to be repeated. This is occasionally necessary if during the first attempt, the eye rolls or for whatever other reason the ring is determined not to be well centered.
There isn’t any guaranteed way to prevent this from happening. Although it can look alarming if large, there is no effect on the final outcome and vision will be unaffected by this redness.
Of course, if a flapless procedure like PRK/TransPRK/epiLASIK is chosen, there will be no risk of SCH, but on the other hand the usual cons of PRK type procedures such as delayed visual recovery need to be considered.
Depending on the size of the red patch, cases of SCH can take anywhere from several days to several weeks to fully resolve. During this time, there is no specific method to hasten recovery, but do use the usual post LASIK eyedrops like antibotics and artificial tears as advised by your doctor.