nearsightedness

contact lens addicts

Yesterday I had the not so pleasant experience of having to scare one of my patients out of wearing contact lenses. It inspired me to write a little about contact lenses and those who (over)wear them.

It has occurred to me, over the past year or so, that some patients are addicted to wearing contact lenses. These people are like the crack addicts of the ophthalmic world. They need contacts. They'll do anything to get contacts. They will come in begging for samples. And when you suggest to them that they should quit, they freak out!

For these people, going straight and cleaning up their act means having to wear glasses. And just like any other addiction, its hard for people to quit cold turkey. They come up with all sorts of excuses like "I don't like my frames", "I lost my glasses", "Glasses make my face look fat". Well I got news for you, Chubs... Its not the glasses!

Anyway, this is where I come in. I'm like the motivational speaker on those self help tapes that tell people that they are strong and in control of their lives. "Where there's a will, there's a way" and all that good stuff. Oh and also, if they don't quit, they could go blind.

That last note usually helps me get people's attention. And it worked yesterday with my 19 year old patient who had been wearing coloured contacts (not the best quality lenses) 7 days a week for the last 5 years. She does not own a pair of glasses and therefore has been wearing her contacts from morning until night.

 

Why is this so bad?

The cornea, which is the clear dome at the front of our eyes, has a very high demand for oxygen. The only place the cornea can get oxygen is from the air around us. As you can imagine, covering the cornea with a piece of plastic will significantly reduce the amount of oxygen that gets through. The cells of the cornea starve for oxygen and start to break down causing the cornea to become less clear thus making vision blurry.

The body's response to this lack of oxygen involves creating new blood vessels into the cornea. This is called neovascularization. While this may seem like a good idea, it is actually the exact opposite. If the blood vessels grow too far into the cornea, they can begin to obstruct/distort vision. There is no way to reverse neovascularization of the cornea. It can be stopped or slowed down by decreasing contact lens wear. But if it is very significant, the only treatment is corneal transplant surgery. And believe me when I tell you, you do not want corneal transplant surgery.

Cornea with stitches, post transplant

Cornea with stitches, post transplant

 

Its sad to see a person as young as 19 be at risk of permanent vision loss. But, with a little treatment and staying out of contacts for a while, her eye health (and vision) should improve.

As useful and convenient as they are, contacts can cause a multitude of different ocular problems if worn incorrectly. All patients who wear contact lenses should have regular eye exams.

Lil' Wayne and cataracts

"You can't see me baby boy, you got them cataracts" - Lil' Wayne in Best Rapper Alive

Who said rap music is bad for you? I think its educational! Lil' Wayne may not know exactly what a cataract is, but he definitely has the right idea.

A cataract is the clouding of the lens that is inside the eye. As the lens becomes more clouded, vision becomes blurred due to light being blocked or scattered. This is the same lens that we use to focus at near objects. The same lens that stops working around the age of 45 and forces people to start wearing reading glasses (See: presbyopia in the "All Kinds of Blurry" post).

Everyone will develop cataracts at some point in their lives if they live long enough. How much and how fast depends on the individual and the environment. Medical conditions like diabetes can cause cataracts to develop faster. Sunlight is the main environmental factor. So, grab those sunglasses!

Congenital cataracts - It is possible to be born with a cataract. I recently saw a 5 year old boy who had a cataract in one eye. Another reason why kids should have regular eye exams.

Traumatic cataracts - Getting hit in the eye can cause a cataract. Wear protective lenses whenever possible!

How do you treat cataracts?

The only treatment is removal. The cloudy lens is removed and new clear plastic lens is inserted in its place. The surgery takes about 10-15 minutes per eye and requires an incision less than half a millimeter in size!

Who knows, maybe next week Kanye West will rap about Macular Degeneration... Stay posted!

 

"I spent a G on these frames, but my vision is priceless" - Lil' Wayne

 

Contact lenses

They come in a variety of shapes, sizes, and colours...

Soft contact lenses (SCL):These are the most common and they are disposable.

  • This means that after wearing the lenses for a period of time, they are disposed of and a new, fresh pair is used
  • Lenses can be monthly (ex. Air Optix, Frequency 55, Proclear, Biofinity, etc), two week (Acuvue Oasys), and daily disposable (CIBA Dailies, Acuvue 1-day, etc)
  • Also available for astigmatism and patients over 40 who need reading glasses (more information in my post All Kinds of Blurry)

Daily disposable lenses are the healthier option for your eyes for the simple reason that a fresh, sterile lens is being used every single time. Most infections are a result of poor storage or lens care. A lot of these problems can be avoided with daily lenses.

Rigid Gas Permeable (RGP):AKA Hard lenses. Considered older technology but actually provide better optics, better oxygen flow, and less infections. Less popular simply because they are uncomfortable to begin with. But patients who get used to them, stick to them.

 

Hybrid Lenses:Combination of a hard lens with a soft "skirt". Supposed to provide superior vision of RGPs without being as uncomfortable. But, they haven't been as successful as expected.

Orthokeratology (Ortho-K):Contact lenses that are worn while you sleep. Over night, they flatten the cornea and temporarily correct near-sightedness. Also mentioned in my post Laser Eye Surgery.

Important things to REMEMBER: No matter how good a contact lens claims to be at allowing oxygen pass, or keeping your eyes hydrated, or preventing bacteria from sticking to it, at the end of the day it is still a piece of plastic in your eye.

Contact lenses are considered to be medical devices and, as such, should be looked at by a doctor before they are dispensed and any time the patient experiences any problems.

Three big NOs:

  • No sleeping
  • No swimming
  • No tap water

These are the quickest ways to cause infections which can be potentially vision threatening (see picture below).

Other uses:Contact lenses are not only used to improve vision. Here are a couple of other interesting uses:

  • Diabetic patients
    • Lens changes colour when sugar levels in tears increase
  • Bandage
    • Used to cover scratched corneas or after LASIK surgery
  • Administer drugs over long periods of time
  • Tracking eye movements in ocular studies

FAQ:

Q: Can I get coloured contact lenses even if I have no prescription?

A: Yes. But FYI, these lenses tend to be the least healthy for your eyes.

Q: How often should I replace my contact lens case?

A: Usually every 3 months or when your solution runs out. Whichever comes first.

Q: If I wear contact lenses, do I still need a pair of glasses?

A: Yes, you should always have a good pair of glasses to give your eyes a break and just in case something happens to the contacts.

Q: What if I'm on vacation and I forgot my contact lens solution and my contacts are bothering me and there isn't a pharmacy close by and my cousin says its no big deal, can I just store my contacts in tap water?

A: No. No tap water. Ever. I hope that is clear enough :)

All kinds of blurry

In my very first post I wrote a little about myopia, which is near-sightedness. Here we'll discuss all the other "-opias" and "-isms" that can make your vision blurry. They are generally referred to as "refractive errors".

A quick review of Myopia. It is due the eye being longer than average. So, rather than an image being focused right on the retina, it falls a little short. Of course, this gives us blurry vision for distant objects which can be corrected with "minus" prescription glasses and contacts, or laser surgery. Example of near-sighted prescription is: -3.25.

 

Hyperopia. This is what we call far-sightedness. As you would expect, a hyperopic person would have more trouble with near and less trouble with distance. This is a result of the eye being a little bit shorter, thus images fall behind the retina. This is corrected with "plus" prescriptions. Also can be corrected with laser.

 

Astigmatism. Is not affected by the length of the eye. Astigmatism is a result of the shape of the front of the eye (the cornea). With astigmatism, the cornea is not perfectly round, it is a little steeper in one direction than the other. The common analogy is a basketball compared to a football. So, light cannot be focused to one point on the retina. It is split by the different curves of the cornea. To correct this, the prescription needs two powers (one for each curve of the cornea). An example of this would be -1.50 -0.75 x180. The "-0.75" is the astigmatism part of the prescription and "x180" shows that this prescription needs to be placed at 180 degrees. Astigmatism can be corrected with glasses, contacts, and laser.

 

Presbyopia. The first three refractive errors are mostly hereditary. The last one, however, is purely age-related and happens to everyone. As we age, the accomodative system (system inside our eyes that helps us focus at near) slowly stops working. Eventually, as we make it through our 30s into our 40s, we notice that things up close are not as clear as they used to be. Often, patients will say that they need to hold reading material further away. And eventually no matter how far away you hold it, its just not clear enough! Correction usually involves reading glasses, bifocals, or multi-focal contact lenses. Laser surgery is not a very useful option because it does nothing to improve the accomodative system.