Refractive errors affect approximately 20 - 30% of the normal population. Blurred vision, headache, and eyestrain are common symptoms of uncorrected refractive errors. Glasses or contact lenses are usually prescribed for correction of refractive errors. Recent advances in technology, have made it possible to permanently correct refractive errors using Laser treatment. In USA, about 2 million refractive laser treatment procedures are performed every year.
What are refractive errors?
Refractive errors refer to condition of the eye wherein the rays of light do not get focused on the retina, the light sensitive layer of the eye. In Myopia (short-sightedness) rays of light fall short of the retina, hence require minus power glasses, whereas in Hyperopia (far-sightedness) rays of light come to a focus behind the retina, hence require plus power glasses. In Astigmatism the rays of light come to focus at two different points, and therefore require cylindrical power glasses for better vision.
What are the options for correction of refractive errors?
Refractive errors can be corrected using glasses (spectacles) or contact lenses. Permanent correction can be achieved by reshaping the cornea using laser treatment (LASIK).
Glasses or contact lenses have the advantage that they are economical, and can be replaced whenever there is a change in refractive error. However, with higher refractive errors, glasses become thicker, heavy and uncomfortable to wear, besides poor cosmesis. The field of vision is also smaller and restricted with glasses as compared to contact lenses. Contact lenses need to be worn on the eye, and provide good quality of vision compared to glasses. However with contact lens wear, there is a potential risk of infection, which if severe can result in loss of vision. Hence good hygiene needs to be maintained, along with proper care of the contact lens to prevent infections. In comparison, laser treatment although expensive, provides a permanent correction of refractive error, with better unaided vision following treatment.
What is LASIK ?
LASIK (laser in situ keratomileusis), is a laser procedure, wherein the shape of the cornea is altered using the Excimer laser to painlessly correct refractive errors. A specialized instrument called the microkeratome, is applied on the cornea to lift up a thin flap prior to applying laser treatment. The procedure takes only 10 minutes to perform, and good visual improvement is noted the next day.
Who is eligible for LASIK?
Well not everyone who wears glasses or contact lens is eligible for LASIK. It is usually performed in individuals above the age of 18 years, with stable refractive error. There should not be any other associated eye disease. Preoperative evaluation of the corneal shape and measurement of corneal thickness is essential to rule out corneal abnormalities.How are the results of LASIK?
The results of LASIK are quite satisfactory. In experienced hands, with modern laser machines, 98% patients are within 1 diopter of refractive error following treatment, with unaided visual acuity of 6/12 or better. 85 ? 88 % patients achieve unaided 6/6 or normal vision following LASIK. There is a significant improvement in unaided visual acuity, and patients are able to carry out their normal daily activities with greater confidence. Tiger Woods, the golf champion underwent LASIK in both eyes, in 1999 and has been playing active golf since then winning several championships
What is customized LASIK?
Besides the normal refractive errors measured routinely, the total optical imperfections of the eye can now be measured using a special instrument called the aberrometer. When this data is used to correct the optical imperfections using laser treatment, it is called customized LASIK. Different laser manufacturers have given specific names to this customized LASIK treatment with their machines, such as zyoptix, custom vue, custom cornea etc. To perform customized LASIK, the laser should have smaller laser spot size, active eye tracker, and high speed of treatment. Customized LASIK is useful in patients with significant amount of higher order aberrations.
What are the complications of LASIK?
LASIK procedure is quite safe if performed by well trained corneal surgeons. Undercorrections and overcorrections are usally minimal, and if present can always be corrected by laser re-treatments. There is usually a transient phase of dryness in the eyes, with mild glare while looking at bright lights. Infections are extremely rare if the procedure is performed in an operation theatre like environment, with sterile precautions.
Should I undergo LASIK?
The key question in everybody?s mind who wear glasses or contact lens. Excimer laser treatment for correction of refractive errors has been present for over 15 years now, and millions of people have undergone this procedure with good results. The procedure has been proven to be safe, if performed by an experienced surgeon. It is important to have a good discussion with the treating surgeon prior to undergoing laser treatment for correction of refractive errors. Your surgeon will examine your eyes and then decide if you are a suitable candidate for laser treatment.
If I am not a suitable candidate for LASIK are there other options?
Yes there are other options for correcting refractive errors not amenable to LASIK. There are special intraocular implants called ?Phakic IOL?s? which can be placed inside the eye to correct higher refractive errors. In some patients, the natural lens can be replaced with an implant to correct higher refractive errors. Suitability for these procedures require detailed evaluation of the eye.
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