Correct focusing of images in the eye is determined by the focusing power of the cornea and the lens of the eye in relation to the length of the eye. Either the cornea or the lens or both can be changed to correct errors of focusing (called refractive errors) such as nearsightedness, farsightedness, or astigmatism. A "cataract" is a clouding of the natural lens in the eye and modern treatment of cataract involves removing this clouded lens and replacing it with an artificial lens called a lens implant. Exactly the same operation can be done when the lens is not clouded in order to change the power of the lens as a way to correct nearsightedness or farsightedness. This is called Refractive Lens Replacement.
For a relatively high amount of farsightedness (hyperopia) refractive lens replacement is, in our opinion, the only good surgical choice at this point in time. Depending on individual considerations, it may be the best procedure for any degree of hyperopia and perhaps for some cases of extreme myopia. Refractive lens replacement is less likely to produce side effects such as starburst, glare, halos, and decreased night vision than any of the corneal procedures. Most patients have none of these side effects after refractive lens replacement, but they remain possibilities.
Since refractive lens replacement requires surgery inside the eye and not just on the cornea, it can be associated with some potentially severe complications rarely if ever seen following any of the corneal procedures (e.g. LASIK, ALK, RK, PRK). These include, but are not limited to:
1. Infection inside the eye (endophthalmitis). We estimate the probability of this to be less then 1 in 2,500, but if it occurs it is very serious and can cause loss of vision or blindness if unsuccessfully treated.
2. Retinal detachment. We estimate the probability of this to be about 1 in 1,000 cases in hyperopic patients, but considerably more likely in myopes and especially high myopes where it may reach a likelihood of as high as 4 to 5 in 100. Retinal detachments tend to occur in high myopes even if they have no surgery. The probability of retinal detachment increases if a capsulotomy (see "6" below) is needed. A capsulotomy is necessary in 30% to 50% of young patients who undergo lens replacement. Some retinal detachments can be successfully treated, but not all and this can result in severe loss of vision or blindness.
3. Cystoid Macular Edema. This is a swelling in the layers of the center part of the retina which can occur after any type of surgery inside the eye, including refractive lens replacement. It seems more likely with increasing age. It may occur to some degree in several out of every 100 eyes. Fortunately it usually gets better with time, but it can delay the return of good vision and sometimes does not get better and can result in permanent decreased vision.
4. Damage to the iris or pupil. This is not likely, but can occur. It if should, it can interfere with the best possible vision and can produce severe glare, light sensitivity, and a cosmetically displeasing appearance to the eye.
5. Eye pressure. There is commonly some fluctuation of the eye pressure following refractive lens replacement in the first few days or weeks following surgery. Rarely the pressure can remain elevated and result in the eye disease called "glaucoma".
6. Need for capsulotomy. In about 1 out of 2 to 3 eyes following refractive lens replacement the "capsule" behind the implant becomes clouded to some degree. This is usually very easy to correct using the YAG laser, but having the capsule opened is felt to increase the risk of cystoid macular edema and retinal detachment.
7. Effect on accommodation. (See "Presbyopia" section). The ability to focus at different distances automatically in young people is done by the natural lens of the eye. Following refractive lens replacement, this ability is gone and the resulting effect must be understood. In patients near or over 40, this changing focus ability is already decreased or lost and is not generally much of an issue. It is, however, an important consideration, especially in younger people. This surgery creates "instant presbyopia" and unless it is compensated for by monovision there will be a need to use glasses for near tasks such as reading. If you are a candidate for Refractive Lensectomy, you will be given a separate booklet to study.