Surgical Treatments for Myopia, Hyperopia, Astigmatism & Presbyopia
Brief Overview of the Refractive Conditions
In myopia the cornea (front of eye) has too much curvature, the eye is too long or a combination of the two. The result is the patient sees blurry at the distance and usually good at close ranges. In laser surgery, the goal is to flatten the cornea to compensate for the degree of myopia.
In hyperopia the cornea has too little curvature, the eye is too short or a combination of the two. The patient will typically have good distance vision but difficulty with extended close work. The laser techniques effectively steepen the curvatures to correct the hyperopia.
In astigmatism the cornea basically has two different curvatures and thus the vision is distorted. Patients can have mypopia with astigmatism or hyperopia with astigmatism. Laser surgery for astigmatism is designed to effectively correct any myopia or hyperopia and in addition to compensate for the different curvatures from the astigmatism.
In presbyopia the lens inside the eye loses flexibility to the point that the patient gets a gradual decrease in the ability to focus their eyes at close objects. This is typically something that occurs in adults over age 40 and can occur if you are myopic, hyperopic or have astigmatism. The laser techniques currently being utilized reshape the cornea to account for both the distance and the near prescription at the same time, much like a multifocal contact lens.
PRK (PhotoRefractive Keratectomy)
PRK is a laser procedure that permanentely reshapes the cornea to correct myopia, hyperopia and astigmatism. It is sometimes referred to as LASEK (note the E) which stands for Laser Epithelial Keratomileusis and or "flapless Laser". This treatment uses a computer driven eximer laser (directed by the surgeon) that removes the outermost layers of the cornea to correct the patients prescription. The laser removes both the outer epithelial layer as well as a portion of the internal stromal layer of the cornea. Since the epithelium is removed in PRK the patient typically will use a bandage contact lens until the epithelium grows back (less than 1 week). PRK is most often used in cases where the cornea is too thin for LASIK (note the "I") which is described below. The picture below shows Dr. Mason at TLC Laser Center in front of the VISX laser (an eximer laser used for PRK & Lasik).
LASIK (Laser-Assisted In Situ Keratomileusis)
LASIK (note the "I") stands for Laser-Assisted In Situ Keratomileusis and is a procedure that permanently changes the shape of the cornea using an excimer laser. It is used to correct myopia, hyperopia & astigmatism and is sometimes referred to as ILASIK to avoid confusion with LASEK (above). It is similair to PRK with the exception that a thin flap is made on the outer section of the cornea using either a laser (Intralase) or a microkeratome (blade). The flap is then lifted to expose the stroma (internal layer of the cornea)and the laser is then used to reshape it to correct the patient's prescription. The flap is then laid back down and sealed to the cornea. This procedure typically has a faster recover period with less discomfort than PRK because the epithelium is left intact (in the flap portion).
ICL (Implantable Contact Lenses)
Implantable Contact Lenses are one of the newest remarkable technologies currently available to treat the patients previously outside the power ranges for PRK or LASIK. Currently the ICL we have had experience with is the Visian ICL. The Visian ICL is made of Collamer, an advanced lens material that is highly biocompatible. The material itself is one of the reasons that sometimes you will see the letters ICL referred to as "Implantable Collamer Lenses". Collamer does not cause a reaction inside the eye and contains an ultraviolet filter that provides protection to the eye. In the very high powers of myopia or for those with corneas too thin for laser a new development utilizing implanted "contact lenses" behind the IRIS (colored part of eye) has shown excellent results. We have had patients that were told in the past they could never have Lasik because their prescription was too high and they had ICL done with extremely satisfaying results. The surgical field is constantly changing and that is why our goal is to keep you apprised as to the options available.
Co-Management of Refractive Surgery Services
Refractive surgery is an extremely delicate procedure, involving precision, experience, knowledge and the skill of the surgeon. In our office we co-manage surgeries with Ophthalmic Surgeons with which we have the utmost respect. Dr. Mason routinely provides pre operative and post operative care for refractive surgery patients. He takes the necessary time in consultation to cover the myraid of options and procedures available and will guide you which one is the best option for your eyes and vision. and if you have questions or are interested please call our office for a consultation.
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Dr. Daniel L. Mason, Optometrist
(619)656-1081