Intraocular Techniques
All of the surgical vision correction techniques we have discussed so far (including LASIK and PRK) are done at the surface of the eye. Intraocular techniques, as the name implies, are done within the eye. Two intraocular techniques are available: Phakic Intraocular Lenses — often referred to as an Implantable Contact Lens (ICL) and Refractive Lens Exchange (RLE).

Intraocular techniques are derived from cataract surgery. (Cataracts are opacities in the crystalline lens that usually occur with age.) In modern cataract surgery, the crystalline lens is removed and replaced with a clear artificial lens called an Intraocular Lens (IOL). Many millions of cataract procedures are done every year around the world, so the technique has been greatly refined. Most ophthalmologists are skilled in cataract removal and IOL implantation.

Until recently, the crystalline lens was removed only when cataracts were present. Then some surgeons realized that the crystalline lens could be removed and replaced with an IOL as a way to correct refractive errors in eyes without cataracts. This technique is called a Refractive Lens Exchange. The term applies because the crystalline lens is replaced with an artificial lens of a specific power to enhance vision.

RLE is offered in cases of very high degrees of myopia, where LASIK and PRK are less effective. (PRK and LASIK are effective with low, moderate and high prescriptions. But neither PRK nor LASIK is optimum for extreme myopia or farsightedness.)

The phakic IOL technique (ICL) is similar to the clear lens exchange in that an artificial lens is implanted in the eye. However, with a phakic IOL, the patient's crystalline lens is not removed. (The Greek word phakos means "lens"; and a person who has a crystal-line lens is said to be "phakic"; a person whose crystalline lens has been removed, usually due to cataracts, is said to be "aphakic.") In the phakic IOL procedure, an IOL is implanted just in front of the crystalline lens. (One company refers to its phakic IOL as an "implantable contact lens.")

The advantage of the phakic IOL is that, in younger patients, the crystalline lens remains, and the patient doesn't lose the ability to accommodate. Because the crystalline lens is required for accommodation, RLE, which removes the lens, will end the patient’s ability to accommodate and hence reading glasses will be required. However new innovations in intra ocular lenses have resulted in implants that can provide both distance and near vision.

Both the RLE and the phakic IOL’s (ICL) are effective methods for the correction of extreme refractive errors. LASIK and PRK, the standard treatments for the vast majority of refractive errors, are less effective for extreme refractive errors. To some degree, phakic IOL implantation is a reversible technique. CLE, however, definitely isn't. Once the crystalline lens is removed, nothing can replace it.

Advances in Refractive Surgery