I had a 60 year old patient in the office today who I told that she had "early" cataracts. She was a moderate farsighted patient who was seeing 20/30 with her current glasses, and will see 20/20 with her new bifocals. Now, without her glasses, she is able to see only 20/200 at both near and far. Her question to me was, "Are my cataracts 'ripe' enough to come out?" I gave her my standard "canned" answer: "we don't wait for cataracts to be 'ripe' to remove them. The time for cataract surgery is when you are unhappy with your vision, are unable to do all the things you would like to because of your vision, and I can't improve it to your satisfaction with a change in glasses."
This is the standard answer that most ophthalmologists and I will give to patients when their insurance will be paying for the surgery, as there are certain criteria that must be met. Specifically, best corrected vision should be worse than 20/40 and interfering with daily lifestyle. With the aging of the Baby Boomer Generation, and improved refractive lens based technology, I have noticed a paradigm shift in how I view and discuss cataracts.
First, a little anatomy. Think of the eye as a camera. The front surface is a clear window, called the cornea. Behind the cornea is the colored part of the eye, the iris, which acts like a diaphram in a camera. It opens and closes to adjust the amount of light coming into the eye by changing the size of the pupil. Behind the pupil is the lens. When we are young, the lens is clear and able to easily change its shape to focus light onto the back of the eye, the retina. The retina acts like the film in a camera.
Today's discussion will be limited to the lens as I will be describing a new terminology first described by Harvey Carter, MD: Dysfunctional Lens Syndrome.
As I mentioned, when we are young, the lens is clear and is able to change its shape, to focus. This is called accommodation. Aging affects the lens. First, the lens begins to stiffen and lose its ability to change shape and focus. This is called presbyopia, and usually manifests itself in the early 40's, when we start to need reading glasses. Presbyopia will continue over the years, making focusing more and more difficult, ultimately leading to the need for bifocals. As we continue to age the lens then loses its clarity and begins to opacify, leading to the formation of a cataract, or cloudy lens. The cataract will continue to get more and more cloudy over time until it is very hard and dense, a ripe cataract. When a cataract is "ripe", the patient is generally blind in that eye, and cataract surgery is very difficult.
So how do we treat Dysfunctional Lens Syndrome? It depends on what the patient wants:
- Early on reading glasses are used as needed.
- When distance is also effected, bifocals are prescribed.
- Bifocal contact lenses and monovision contact lenses are prescribed to those who do not want to wear glasses.
- Refractive Lens Exchange (RLE) works very well for those patients who do not want to wear glasses or contact lenses. RLE involves removing the dysfunctional natural lens and replacing it with a multifocal artificial lens (IOL) that is capable of focusing light near and far. It is the same procedure as cataract surgery, except there is not enough lens changes (cataracts) for insurance to pay for the procedure.
- Once cataracts become visually significant, they may be removed to improve one's vision. Again there are several choices here, depending on the patient's needs:
- A standard IOL will provide excellent distance vision, provided there is no corneal astigmatism. Astigmatism occurs when the eye is oval in shape, resulting in unequal refraction. Light rays are focused at two different points on or before the retina, and this split focus produces distorted vision. Cataract surgery does not correct this and bifocals will be needed after surgery. If there is no astigmatism, only reading glasses will be needed, as the standard IOL provides no focusing for close.
- For those that do not want to wear glasses after cataract surgery, a premium IOL may be implanted. Insurance does not pay for the premium IOL, or the added visits and testing that is required. Let’s break premium IOL choices into 2 categories:
- No pre existing astigmatism: In these patients, a multifocal IOL is implanted to achieve glasses free vision at both near and far.
- Pre existing astigmatism: In these patients there are 2 choices:
- If one wants to have glasses free vision both near and far a multifocal IOL is implanted to address the near vision problem. Astigmatism correction will than be addressed with LASIK about a month after the cataract surgery.
- If one only wants good distance vision without glasses, a Toric IOL is implanted. These patients will than only need over the counter reading glasses.
In summary, the new paradigm of discussing Dysfunctional Lens Syndrome allows me to discuss the changes in the natural lens, and how they affect my patient’s lifestyle requirements more effectively. My discussion is no longer limited to the term "cataract", with its conotations of being a disease of "old age."