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What are refractive errors? |
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| The need for glasses to correct the vision is known as refractive error. Refractive errors include myopia, hyperopia, presbyopia, and astigmatism, eye conditions that are very common. Most people have one or more of them. Refractive errors can usually be corrected with eyeglasses or contact lens. |
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What is myopia (nearsightedness)? |
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| If you have myopia you can clearly see close objects, but distant objects are blurry. Myopia is caused by the eyeball being too long. Myopia occurs in different degrees from minimal to extreme. The more myopic you are the blurrier your vision is at a distance and objects will have to be closer to you so you can see them clearly. |
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What is hyperopia (farsightedness)? |
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| If you have hyperopia, you can see distant objects clearly, but close ones are blurry. Hyperopia occurs when the eyeball is too short for the light rays to focus clearly on the retina. |
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| If you have an astigmatism, the surface of the eye (cornea) is not perfectly round, rather it is more oval and doesn't allow the eye to focus clearly. The cornea is very important in helping the eye focus light rays on the retina. Astigmatism rarely occurs alone. It is usually accompanies myopia or hyperopia. |
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| If you have presbyopia, you have the loss of the ability to focus up close that occurs as you age. Most people are between 40 and 50 years when they realize for the first time that they can't read objects close to them. The letters of the phonebook are "too small" or you have to hold the newspaper farther away from your eye to see it clearly. At the same time your ability to focus on objects that are far way remains normal. |
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Traditionally for many centuries the simplest (and only) option was wearing spectacles. Then came contact lenses to correct the vision. For many decades now, contact lenses have served well. A wide variety of contact lenses are available serving different requirements and made up of various materials.
The biggest breakthrough in refractive correction came with the advent of Excimer Lasers for removal of spectacles. Excimer laser based surgery has evolved over the years and now various options are available to customize the surgery to the needs of the patient. However, Laser based refractive surgery has some limitations in terms of the refractive error one can correct. This is determined by the thickness of the patient's cornea and the refractive error per se to deal with refractive errors for which laser surgery would not suffice, Phakic Intraocular Lenses were introduced. These lenses are implanted within the eye. Very grossly speaking, it is like implanting a very high precision, high quality contact lens inside the eye. Various types are available but one of them, called the ICL, has taken the lead in recent years. Now, Toric ICL is also available to correct for astigmatism (cylindrical power). |
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Laser in situ keratomileusis, or LASIK, is an outpatient surgical procedure used to treat myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. With LASIK, your ophthalmologist (eye doctor) uses a laser to reshape the cornea (the clear covering of the eye) to improve the way the eye focuses light rays onto the retina. LASIK may decrease your dependence on glasses and contacts or, in some cases, allow you to do without them entirely. According to the literature, seven out of 10 LASIK patients achieve 6/6 vision, but 6/6 does not always mean perfect vision.
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Am I a good candidate for LASIK? |
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| LASIK is not for everyone, and your eye doctor will advise you about certain conditions that may prevent you from being a good candidate for this procedure. For instance, the ideal candidate for LASIK is over 18 years of age, not pregnant or nursing, and free of any eye disease. You should not have had a change in your eye prescription in the last year and should have a refractive error within the range of correction for LASIK. You must also be willing to accept the potential risks, complications and side effects associated with LASIK that will be explained by your surgeon. You should discuss these issues with your surgeon, carefully weighing the risks and rewards. If you're happy wearing contacts or glasses, you may want to continue with them. |
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| With LASIK, the surgeon creates a thin flap in the corneal tissue with an instrument called the Microkeratome. After folding back the flap, a laser preprogrammed with your eye measurements, is used to sculpt the exposed corneal tissue. Once the cornea has been
reshaped, the flap is put back into position where it adheres on its own. |
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Are there different types of LASIK? |
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| LASIK, since it was introduced, has also evolved. Newer and advanced types of LASIK are available to offer the best to patients. These are called ZYOPTIX. To differentiate the standard LASIK from ZYOPTIX, it is called Planoscan LASIK. |
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Personalized treatment protocol have come about to tailor the LASIK treatment to the patients specific needs and eye condition. These are called ZYOPTIX. One of the keys to a successful LASIK procedure is the measurement your ophthalmologist takes to determine your refractive error. Zyoptix entails some more measurements as compared to the standard Planoscan LASIK. These measurements are then entered into the computer software to generate a treatment that is unique to you.
Three types of Zyoptix are available:
- Zyoptix Personalized (wavefront guided LASIK)
- Zyoptix Tissue Saving
- Zyoptix Aspheric
Each of these caters to the specific requirements of the individual patient. A thorough discussion with your surgeon is mandatory to understand which of the treatment protocols would work best for you. |
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What is Advanced Surface Ablation? |
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For some patients, LASIK may not be possible because of a thin cornea or relatively higher refractive error. For such patients we have Advanced Surface Ablation.
Infact, laser based refractive surgery started with a surgery called Photorefractive Keratectomy (PRK). Lasik was introduced to overcome some of the disadvantages associated with PRK namely:-
- Slower recovery (compared to early recovery with LASIK)
- More discomfort (for 2-3 days compared to one night with LASIK)
- Longer time for vision to stabilize (2-3 weeks compared with 1-2 days with LASIK)
- Longer duration of medication ( 3 months compared to 4 weeks with LASIK)
- Some issues with regression of number and haze formation
Advanced surface ablation is the new "avatar" of PRK. It offers the benefit of laser refractive surgery while overcoming the drawbacks of the PRK. |
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How is Advanced Surface Ablation done? |
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This procedure differs from LASIK in that only the top layer of the cornea called the epithelium is removed. This layer is about 60 microns thick. In LASIK, on the other hand, a flap of cornea is created varying in thickness, nowadays, from about 110 to 160 micron. This itself offers the advantage of increased residual corneal thickness with Surface Ablation. Once the epithelium is removed, an excimer laser is used to remove a thin layer of corneal tissue. This process is the same as that in LASIK.
Your surgeon guides the laser with a computer, and the laser beam sculpts the surface of the cornea, decreasing the steepness of curvature for nearsightedness or increasing the steepness of curvature for farsightedness. To treat astigmatism, the laser is programmed to selectively reshape specific reshape certain areas of the cornea more than the others. Some surgeons, now, prefer Advanced Surface Ablation and do not limit it to patients with thin corneas alone.
Overall, the laser based refractive procedures have been around for a sufficiently long time and have proven their safety and efficacy. However, constant research is going on to be able to offer the best to our patients. |
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| Phakic Intraocular Lenses are implanted within the eye and work with the natural lens to correct refractive errors. They are called Phakic lenses because they are implanted into the eye without removing the eye's natural lens. Phakic lens is inserted through a small incision and depending on the type is placed either in front of the iris, behind the iris or is fixed to the iris. Various types are available but one of them, called the ICL, has taken the lead in recent years. Now, Toric ICL is also available to correct for astigmatism (cylindrical power). Unlike corneal refractive surgery, such as LASIK and PRK, the ICL does not alter the structure of the eye, or involve tissue removal. |
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Although the ICL is meant to be a permanent solution for vision correction, the lenses can be removed should the need ever arise. This reversibility and the possibility of changing the power makes it a very attractive option.
Many refractive surgeons have come to believe that for higher refractive errors (that entail significant removal of corneal tissue and alteration of shape), ICL provides superior quality of vision compared to laser based corneal refractive procedures. In any case, it does have a definite role to play for patients with thin corneas. |
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How do I know if I'm a suitable ICL candidate? |
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Candidates for the Visian ICL are between 21 and 45 years of age and suffer from myopia (nearsightedness). The ideal ICL candidate has not undergone any ophthalmic surgery and does not have a history of eye disease such as iritis, glaucoma, or diabetic retinopathy.
Patients should consult their qualified ICL surgeon for a thorough evaluation.
An adequate anterior chamber depth and endothelial cell density are important criterion for a good ICL candidate. |
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What if I have astigmatism (cyclindrical number)? |
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| ICL has a variant called the Toric ICL. They are designed to correct astigmatism thus providing very good vision to such patients. |
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| ICLis placed through a small micro-opening, placing it inside the eye just behind the iris in front of the eye's natural lens. The ICL is designed to stay in position where implanted. |
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What if my vision changes after I receive the ICL? |
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One advantage of the ICL is that it offers treatment flexibility. If your vision changes dramatically after receiving the implant, your surgeon can remove and replace it. If necessary, another procedure can be performed at any time.
Patients can wear glasses or contact lenses as needed following treatment with the ICL. The implant does not treat presbyopia (difficulty with reading in people 40 years and older). However, you can use reading glasses as needed after receiving the Visian ICL. |
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What type of procedure is involved in implanting the ICL? |
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The surgical procedure to implant the ICL is simple and painless.
Your surgeon will prepare your eyes one to two weeks prior to the procedure by using a laser to create two very small openings in the Iris (colored part of your eye which lies between the lens and the front chamber of your eye). This allows for the natural passage of fluids between the two areas, thereby avoiding the build up of intraocular pressure following the treatment.
The implantation procedure itself takes about 15 minutes and is done under topical (drop) anesthesia without any injections
Following surgery, you may use prescription eye drops or oral medication. The day after surgery, you will return to your surgeon for a follow-up visit. You will also have follow-up visits one month and six months following the procedure. |
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Can the ICL be removed from my eye? |
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| Although the ICL is intended to remain in place permanently, a qualified ophthalmologist can remove the implant if necessary. |
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Is the ICL visible to others? |
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| No. The Visian ICL is positioned behind the iris (the colored part of the eye), where it is invisible to both you and observers. Only your surgeon will be able to tell that vision correction has taken place. |
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Will I be able to feel the Visian ICL once it is in place? |
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| The Visian ICL is designed to be completely unobtrusive after it is put in place. It stays in position by itself and does not interact with any of the eye's structures. |
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