What are the possible complications of RK surgery?
Temporary Light sensitivity All patients experience this symptom (also referred to as glare) to some degree. This usually passes after 48 to 72 hours.
Starbursting Effect Some patients can observe a transient effect when observing bright lights especially during evening hours. This is generated by reflection of light from the edge of incisions overlying the pupil, especially in those individuals requiring longer incisions to correct larger degrees of myopia. The vast majority of patients with this complication will improve spontaneously in 4 to 6 months.
Fluctuation in Vision Following surgery visual acuity can be unstable, clear at times while blurry at other times. In general, this a function of corneal instability which follows the placement of deep incisions. As the cornea heals, the duration and degree of visual fluctuation will diminish. This is directly related to the amount of surgery, i.e., the number and length of incisions. Those who have RK surgery for a larger amount of myopia can therefore expect more instability for a longer duration of time.
Undercorrection It has been reported that as many as 30% of RK patients will be left with some degree of under correction. Some of these patients will require further surgery or enhancements determined by visual needs. These enhancement procedures consist of adding additional incisions or lengthening those that have been previously placed .
Overcorrections Because of the precision afforded by existing databases this is a rare occurrence. Most patients do experience a short period of secondary hyperopia (far sightedness) which passes spontaneously in 24 to 48 hours. For those with persistent, symptomatic over correction, surgical intervention either through placement of incision sutures or excimer laser photoablation (see below) might be necessary. Long-term observation of patients who were enrolled in the original PERK study has indicated that there is a tendency towards the development of a progressive effect of RK surgery in as many as 22% of patients. This has generated some concern among refractive surgeons, who, as mentioned before, are now favoring RK surgery on only those with low degrees of myopia requiring much less surgery.
What is Astigmatic Keratotomy?
Astigmatism refers to another focusing problem generated from the two prime lenses of the eye- the cornea (primarily) and the crystalline lens (occasionally). In this condition the eye does not focus to a point because the surface of the cornea (or lens) is not spherical or round in shape. Instead, the surface is ovoid or oval, having one axis of curvature which is steep and another flat. The net effect is a surface that is shaped much like the back of a spoon or a football. In using astigmatic keratotomy, the refractive surgeon aims to alleviate this anomaly in curvature through the placement of short, deep linear or arcuate (curved) incisions. The technique makes use of the same RK technology described above. The steep axis of the cornea is identified and precise incisions are placed to cause a predictable flattening effect and create a more spherical cornea
These incisions are often placed at the same time that RK surgery is performed for those with combined myopic and astigmatic focusing problems.
Patients must consult with an ophthalmologist who can provide the appropriate level of care necessary.