Buying Cheap Shades and Reading Glasses Can be a Headache. Literally.

Its always nice to write a blog that is related to conversations I have with patients in the clinic. This is a topic I discuss with patients almost every single day and I've been meaning to write about for a while. I finally got around to it thanks to a little kick in the butt which came in the form of a little story on the radio.

Recent research done by the consumer group "Which?" in the UK showed some interesting results when I came to assessing the quality of drug store/dollar store/grocery store sunglasses and reading glasses.

The most recent investigation was regarding sunglasses bought at these types of stores. Some lenses in these sunglasses didn't allow consistent amounts of light through, which can make depth perception difficult. Other lenses induced prism, which means that each eye receives two slightly separated images. This can lead to headaches and double vision. And finally, some of the glasses actually induced astigmatism, which can result in blurry vision, discomfort, and headaches.

All suglasses, expensive or cheap, do provide some amount of UV protection. Considering the fact that some of the more serious eye diseases (such as cataracts and macular degeneration) come as a result of UV exposure, I would prefer that my patients wear something cheap rather than nothing at all. However, if you do experience any discomfort, it's probably better to look into a better quality product.

A few years earlier, "Which?" looked into over-the-counter reading glasses or "cheater readers". These are glasses that many people will pick up when they start to notice problems with seeing clearly at near. This is a condition called presbyopia and it affects almost everyone over the age of 45.

While these glasses may "do the trick" for a lot of people, they can induce problems similar to those noted in the sunglasses convo. Firstly, a lot of people have some amount of uncorrected astigmatism. Also, it common for people to have slightly different prescriptions in each eye. OTC readers do not account for either of these things, which leaves patients with slightly blurry vision and forces the eyes to work harder in an effort to overcome the prescription. Secondly, it is important to remember that these glasses are a "one size fits all" variety. Beacause of this, the center points of the lenses (where the vision is most clear) often do not line up with the center of the patients pupils. This can leave patients with discomfort, fatigue, and double vision after prolonged periods of wear.

The best thing to do is have your glasses prescription and eye health checked by your friendly optometrist and then look into a quality pair of prescription glasses.

http://www.which.co.uk/news/2011/08/high-street-sunglasses-fail-british-standards--------262336/

http://www.which.co.uk/news/2010/10/ready-made-reading-glasses---one-big-headache-234513/

Thanks to Jasmina at The Beat 94.5 for passing on the info.

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 :)

Healthy Cornea

Acanthamoeba infection (from tap water)

Corneal Ulcer due to overwear

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.

More info and facts on Facebook and Twitter