Migraines and Your Eyes

Migraines affect a lot of people and those who suffer from them know, they can be very debilitating.

What causes migraines?
The exact cause is still not fully understood. But most evidence generally points to fluctuations in the size of blood vessels in the brain and over-active neurons.

Auras
The changes that occur in the brain slowly spread into the areas that control eye sight (occipital cortex). Eventually causing distortions in vision. These are called Auras.

Often, people will notice flashes of light, zigzag patterns, or even loss of certain parts of vision for up to 15-20 minutes.

Visual Migraines
It is possible to experience these visual side effects without the headaches. It is important to separate these signs from flashes of light that can be associated with retinal detachments.


FAQ:
Q: How can I tell the difference between visual migraines and retinal detachments?
A: Generally flashes associated with retinal detachments are very brief and tend to be in peripheral parts of vision. Visual migraines tend to last for at least a few minutes and can involve up to half of you field of vision. If you ever notices flashes of light or changes in vision, see your eye doctor to be sure.

Q: How do you treat migraines?
A: For some people simple pain killers like Aspirin and Ibuprofen are sufficient. In more serious cases doctors my prescribe neuro-inhibitor like gabapentin or even anti-depressants like amitriptyline.

Q: Does caffeine help?
A: For some people caffeine can be a trigger. But it has been shown in studies that caffiene can actually help reduce migraines. Possibly because caffience causes blood vessels to constrict so it decreases the fluctuations that are occuring. Excedrin is aspirin plus caffeine.

Thanks for reading. Please feel free to pass this information on to anyone who may find it useful. And as always, questions and comments are welcome and appreciated.

See you all in the new year :)

How Trevor Linden Sold Out: An Eye Doctor's Perspective

Before I begin, I would like to say that as most kids growing up in Vancouver through the 1990's, I considered Trevor Linden to be an idol. A great hockey player and role model. As an adult, and more specifically as an eye care professional, my opinions have evolved.

As usual, I'll try to present my information as fact and do my best to remain impartial. But, I can't make any promises ;)

Many of you have probably seen our good friend Trevor on TV, or on the many obnoxious billboards around Vancouver, advertising for clearly contacts. Smiling with his spectacles on while promoting glasses and contact lenses for cheaper prices. "Glass, plastic, and two tiny little screws..." says Mr. Linden. Is that so?

Allow me to present the following points in a bulleted format.

• First, I would like to challenge the notion that glasses are simply glass, plastic, and screws. For those people for whom glasses are a daily necessity, their presence cannot be so cheaply simplified and their importance so easily ignored. Glasses change people's lives. When Johnny Nash sang "I can see clearly now, the rain is gone...", what he was really saying was "I can see clearly now, I have my glasses on". True story. Glasses are a patient's windows into the world. They are a reflection of a person's personality and style. Try to fit that into $38, Trevor.

• Second, my boy Trev had laser surgery a few years back so he's probably forgotten about the importance of specs. We'll see where he shops once he starts needing reading glasses.

• Third, quality and service (or lack there of) cannot be overlooked. What happens when the arm falls off your glasses? Or you need to have the frames adjusted? Will you take them to the Linden residence?

Buying Contact Lenses Online:
A contact lens can be considered a medical device. A lens is essentially a prosthesis. A piece of precisely designed silicone and plastic placed on the surface of the eye for a medical purpose.

If poorly fit, over-worn, or misused contacts can cause inflammations, infections, and neovascularization of the eye which can potentially be vision threatening.

Would you consider it prudent for an amputee to go shopping for a prosthesis online without the consultation of his doctor? Or maybe a cardiac patient can look for good deals on heart valves while buying his new glasses? After all, they are both just pieces of plastic, right?

Trevor Linden, it's time to stop making a "spectacle" of yourself.

For more background information about clearly contacts and Trevor Linden, check out my more recent blog titled How Trevor Linden Sold Out: The Prequel.

Sunglasses: Fashion Or Function?

Function:
UV light from the sun is the biggest environmental factor related to two of the most common eye diseases: cataracts and macular degeneration.

Also, the eyelids have the thinnest skin of any part of the body which makes them more susceptible to damage from sunlight.

Sunglasses provide protection from these harmful rays of light.

Fashion:
A survey by the American Optometric Association showed that a large percentage of patients believed that brand name sunglasses provided more protection than non-brand name glasses. MYTH!!
Even the $10 sunglasses you can buy at the gas station block at least 95% of UV rays.

Yes, some of the more expensive lenses can provide more comfortable vision with better lens material and polarization. But this does increase protection from UV.

So, when you're looking at buying those $300 Prada shades, remember that you're paying mostly for style and branding. Not like that has stopped anyone in the past :)

FAQ:
Q: Is it important for kids to wear sunglasses?
A: YES!! Most of the damage done to our eyes by UV rays from sunlight is during the first 17 years of our lives. Protect your child's long term eye health by putting on them in some shades.

Q: Why are polarized lenses good?
A: Polarized lenses cut down the amount of reflections seen off surfaces like glass and water. This means clearer, more comfortable vision especially when driving or boating.

Q: Are Transitions (lenses that change from light to dark outdoors) better for protecting your eyes?
A: Clear plastic lenses actually provide a lot of UV protection. Transitions don't increase the UV protection but they provide more comfortable vision when outside.

Notice how she becomes happier as the lens tint gets darker. Amazing!

Q: I heard Transitions don't go dark when in a car. Is this true?
A: Yes. Car windows block 100% of UV light so the lenses will not change.

Q: Do my Ed Hardy shades make me look cool?
A: Ummmmmm....

Thanks for reading. Hope you all found this info useful. Please feel free to pass it on to anyone who may find it interesting.

Ocular Dominance

The same way we are right or left- handed, we also have one eye that dominates over the other. However, these two concepts are not all related and it is possible to be left-handed and have right eye dominance or vice versa.

Knowing which eye is dominant is important in eye surgeries and when fitting contact lenses. It's also important for athletes, especially in sports that require precise aim, such archery.

So how do you know which eye is dominant? I have devised a little test (follow with pictures below):
- Form a diamond shape with your hands
- Holding this diamond, stretch your arms out ahead
- With both eyes open, view a small object at a distance through the diamond (such a clock or light switch on the wall)
- Close one eye at at time

When your dominant eye is closed, the object will be hidden by your hands. When your non-dominant eye is closed, the object will be visible.

I have attached pictures with examples of a person who is Right eye dominant.

Thanks for reading. Please feel free to send any questions or comments my way. Merry Christmas!

Flashing Lights: It's A Camera... It's Lightning... No, It's Your Retina!

It's not uncommon for patients to come in to the clinic and mention they have recently seen something that looked like a streak of lightning or a flash bulb going off in some part of their vision.


How does this happen?The retina is a thin film that covers the inside of our eyes. It is the part of the eye responsible for receiving light signals and sending them to the brain. As you can expect, it needs to be very sensitive.

Due to this high sensitivity, any small movement of the retina can cause signals to be fired back to the brain, making us think that eye is sensing light.


3 most common situations in which flashes are noticed:
1) Patients with near-sighted prescriptions. Near-sightedness is mostly due to the eye ball being larger than average. As the eye grows, the retina becomes stretched. This can lead to areas of thinning and tension.

2) The vitreous gel inside the eye is attached to the retina in multiple areas. Movement of the vitreous can pull on the retina leading to the sensation of flashes.

3) Pressing on the eye. Mechanically releases the chemicals (Phosphenes) that start the signal to the brain.


FAQ:
Q: Are flashes a sign of something bad?
A: Potentially. Flashes could be the first signs of the retina is being pulled, torn, or detached.

If you notice flashes in your vision, especially if combined with new floaters, it is very important to see your eye doctor right away to make sure there are no signs of any tears or detachments.
Q: Do people who have had laser eye surgery still need to worry about their retinas?
A: YES YES YES!!! It is vital for patient's who have had any kind of surgery to have regular eye exams.


Thanks for reading. Please feel free to send me questions and comments about this or any other topic.

Why Josh Koscheck Lost: An Eye Doctor's Perspective

Of course, I'm here to discuss reasons other than Georges St. Pierre's obvious superiority as an MMA fighter. After all, this eye doctor is unbiased and simply here to impart knowledge related to eyes and eye health.

So, why did  Josh Koscheck lose?

It all started early in the first round of the UFC 124 championship bout on Saturday evening. GSP began landing his lightning quick, left-handed jabs to the right side of Koscheck's face. By the end of the first round, his right eye was almost completely swollen shut.

Now, fighting with one eye closed presents multiple challenges. The first, and most obvious, is that Koscheck was not able to see attacks coming from his right side very well anymore. But what I believe to be a more difficult problem to adjust to is the loss of depth perception one encounters when both eyes are not open.

We need both eyes open and working together to perceive depth. Its the main concept behind 3-D movies. Koscheck was basically trying to fight GSP in 2 dimensions. That must have made it nearly impossible for him to judge not only the punches coming towards him but also the punches he was trying to throw (especially if that is his dominant eye).

Doctors confirmed that Koscheck suffered a broken orbital bone, which is serious injury that can result in damage to the muscles and nerves surrounding the eyeball. Also of concern in this case would be the potential for retinal detachments which could lead to blindness if not dealt with immediately.

Josh Koshcheck, it's time to see your eye doctor.

See also Mirko Cro Cop's Eye Injury before his previous fight with Frank Mir.

Computer Vision Syndrome

I have a lot of patients who come in with complaints of eye strain while on the computer, while at work and home.

This is a condition referred to as Computer Vision Syndrome (CVS).
What causes CVS?
1) Need glasses? Uncorrected refractive error (learn more here) can make viewing the computer monitor very uncomfortable.

2) Looking at a computer monitor requires the focusing system inside our eyes to work constantly. Essentially fatiguing the tiny muscles inside our eyes.

3) Reflections from the screen can make it difficult for our eyes to focus accurately, thus causing our eyes to work harder.

4) Incorrect viewing angle can force the muscles on the outside of our eyes to work harder and fatigue.

5) People tend to blink less when at the computer. This leads to dry eyes.

What can be done?
1) First and foremost, get an eye exam. Even if you don't need glasses for other things in life, a simple pair of computer glasses may cure all woes.

2) Take breaks!! Remember 20/20/20. Every 20 minutes, look into the distance (at least 20 feet away) for at least 20 seconds. This will help relax your eyes.

3) Screen protectors are useful. Also, anti-reflective coatings on glasses are very helpful.

4) Ergonomics! Our eyes are most comfortable when looking slightly downward. There are very detailed workplace guidlines available for positioning and posture at the computer.  The American Optometric Association recommends that the center of the monitor should be approximately 15-20 degrees below eye level.

5) Blink more. Make a conscious effort. Also, using artificial tears can help moisturize your eyes. Remember our last discussion on Visine. Always best to ask your eye care professional which drops are best for you.

Thanks for reading. As always, questions are welcome and please feel free to forward this information on to anyone who may be interested.

Visine

Picture this: You're eyes are a little irritated, possibly even a little red. You're not sure why this is happening, but you figure an eye drop could help. You walk into the eye drops section in the pharmacy and you're bombarded by about 131,239 different types of eye drops that tell you they do all sorts of wonderful things. So you pick the one with the name you've heard and claims to do what you want... Visine.

Sometimes it works, sometimes it doesn't. But you give it a try nonetheless.

So, is Visine bad for your eyes and why?

1) The active ingredient in the original Visine is Tetrahydrozaline Hydrochloride. It works by constricting blood vessels. Over time, the blood vessels will stop responding to it and even have a rebound effect, where they get more dilated and red than before.

2) The preservative used in all Visine drops is Benzalkonium Cholride (aka BAK). It has been shown to be one of the most likely to cause ocular toxicity and irritation. Most pharmaceutical companies don't BAK in their medicated eye drops for this reason.

If you insist on using Visine for dry eyes, consider using the preservative-free formula.

FAQ:
Q: Can I use Visine to get rid of Pink Eye?

A: No. Pink eye is a viral infection of the eye and should be looked at by your doctor. He or she can then determine which drops (if any) are needed. Learn more about Pink Eye Here.

Q: What other drops should I use?

A: There are many options for dry eyes, allergies, contact lenses, and infections. Its best to ask your friendly neighborhood eye doctor what is best for your eyes.

Q: Is it true that a few drops of Visine in someone's drink can give them an upset stomach (like in Wedding Crashers)?

A: A few drops probably wouldn't do much. However, a lot would likely make a person very sick. Aside from vomit and/or diarrhea, it could affect a person's vision, heart rate, and body temperature. So, I would not recommend trying it :)

Stye In My Eye

What is a Stye?
A stye is basically a blocked gland in the eyelid which becomes infected. Kind of like getting a pimple on the eyelid. Bacteria, skin cells, and oil can cause the blockage.

The medical term for a stye is Hordeolum. They tend to be painful and they can be either internal or external.

How are styes treated?
Simple therapy involves applying heat the affected area to express the gland and release the blocked material.
In more difficult cases, doctors may prescribe ointment and/or oral meds.
And in the some cases, minor surgery may be require to remove the stye.

How do you prevent styes?
Lid hygeine. Simple things such as warm compresses and gentle lid scrubs can help keep the eyelids clean and healthy.

To do this you simply warm up a cloth or towel with warm water and apply the heat to closed eyelids for 5 minutes. At the end of the 5 minutes use the warm towel to gently massage your eyelids and then lightly scrub at the eyelid margin to wipe away any debris.

Doing this on a daily basis will help prevent blockage and inflammation of the eyelid glands.

For patient who have Blepharitis (eyelid inflammation), it is important to do these warm compresses twice daily. Click here for more info on Blepharitis.
 
Thanks for reading. Please feel free to pass this information on to anyone who may find it useful.

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

Lazy Eye

"Contrary to what some believe, a lazy eye is not one that doesn't like to wake up and go to work in the morning."
- Anonymous Eye Doctor with a sense of humour

The medical term for Lazy Eye is Amblyopia

So why do eyes become lazy?

• The brain is very picky! When it is not receiving a clear image or if it is receiving double images, it begins to shut off connections to the eye that is causing it the most grief
• This process usually happens during childhood and if it is caught before the age of 7, it can be reversed depending on how bad the situation is and how cooperative the patient is

There are two main situations in which this happens:

• Eye turn
• In this case, the patient probably has double vision so the brain will stop communicating with the eye that is turned in/out, which will stop the double vision
• Sometimes surgery is needed to straighten the turned eye, other times simple wearing a patch over the good eye will help force the turned eye back
• Difference in prescription
• If there is a large difference and one eye is very blurry, the brain will again shut it off because it doesn't like dealing with two eyes producing different images
• Glasses are the obvious answer. Sometimes a patch over the good eye will help force the blurry eye to work harder

As you can see a Lazy Eye problem actually becomes more of a Picky Brain problem.

And as the saying goes, "you can't teach an old dog new tricks".

So, once the brain has made all the connections it wants to make, it is very difficult to make it go back. This is why it is important to catch it early! (Before age 7 or 8)

After this cutoff, even providing a patient their full prescription may not improve their vision because no matter how clear the image is, it is not being sent to the brain.


FAQ:
Q: Can a person have 2 lazy eyes?
A: That is a fantastic question! And, yes. I recently blogged about a patient I had seen who had high astigmatism in both eyes. So the connections for both eyes were not fully formed during childhood due to blurry vision and at this point in her life, glasses did not help very much.

Q: What is astigmatism?
A: The answer to this can be found in am earlier post called "All Kinds of Blurry" along with info on other causes of blurry vision

Q: How early should kids have their eyes checked?
A: Both the Canadian and American Association of Optometrists recommend that children have their first eye exam at 6-12 months and again at age 3.

Thanks for reading. I hope this information was helpful. Please feel free to send me any questions or comments. And also pass this on to anyone who may find it useful.

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.

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Doc, My Vision Is Blurry But Glasses Don't Help!

Last week, I had a patient (let's call her Mary) come to see me because she noticed that she was having difficulty seeing the board at the front of the class clearly. Mary was in her early 30s and mentioned she had worn glasses for a little while as a teen but never thought they helped very much.

Turns out that our friend Mary has a prescription with high astigmatism in both eyes. While many of my near-sighted friends and patients can attest that their vision progressively gets worse throughout their teenage years and into their twenties, astigmatism is generally present from childhood and remains relatively constant throughout our lives. (Learn more about astigmatism in the "All Kinds of Blurry" post)

Why is this important? This means that since Mary was a child, her brain has been receiving blurry images. And our mushy, emotion-filled noodle is a very picky person. If it sees blurry images (or double images, for that matter), it will stop forming connections with the eye that it dislikes (in Mary's case, that was both of her eyes!).

This process is called Amblyopia. If we catch these types of high prescriptions before the age of 7, its usually simple enough to reverse the process and convince our gray and white-mattered friend to start liking the patient's eyes again. Unfortunately, in a case like Mary's there is not too much to be done. At this point, not glasses or contacts, not even lasers will be able to significantly improve her vision.

But this doesn't mean we don't try! A lower prescription was given that did mildly improve vision and we hope that Mary's eyes (and brain) will adapt with time.

What is the moral of the story? Kids should get their eyes examined early and often to catch high prescriptions or changes in prescriptions and to avoid amblyopia!

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Night Vision

Remember to find me on Twitter and Facebook for more interesting Eye Info.

Night Vision:

As was mentioned in an earlier blog, there are two types of cells in the eye that detect light: Rods and Cones.

• Cones are for bright light and colour vision. Rods are for night vision and detecting motion in our peripheral vision.

• Rods are very sensitive to small amounts of light because they have a high amount of pigment to absorb light and because there are many more rods than cones.

Night Vision Goggles (NVG)

There are multiple steps to NVG function:

• First, light is gathered
• Sensors detect small amounts of light that are reflected off objects (this includes low levels of infra-red light which is not visible to the human eye)
• Then, light is amplified
• Just like turning the volume up on a stereo, the small amounts of light are made brighter
• Finally, an image is projected
• The new amplified image is shown on a small LCD screen

Since night vision goggles are sensitive to infra-red light, objects that give off a lot of heat will appear very bright (ex. light bulbs and headlights)


Humans vs. Animals:

Human night vision is very poor compared to most animals. This is because a lot of animals have an extra layer in the retina called tapetum lucidum

• This extra layer reflects light within the eye, basically making it more intense (kind of like NVGs)
• It is also the reason why we see different coloured reflections through the pupil of most animals

FAQ:
Q: What if a person had only rods, and no cones?
A: This person would be completely colour blind because rods cannot detect colour. They would also have very poor vision since cones are needed for central vision.

Q: How many rods are there in the retina?
A: There are approximately 120 million rods and about 7 million cones. Cones are packed tightly in a tiny central area called the macula. Rods are spread out over the rest of the retina.

Q: Do night vision goggles always show a green image?
A: Yes. This is done deliberately because human vision works best with greens and yellows.

Q: Can I get night vision goggles?
A: Yes, but don't expect them to be as cool as what you see in movies. Goggles that are available to consumers are older technology and lower quality. The newer, better stuff is reserved for military use only!

Q: Can I get tapetum lucidum?
A: Not unless you plan on stealing a raccoon's eyes. Good luck.

As always, thank you for reading. Please feel free to pass this information on to anyone who may find it useful. Questions, comments, and suggestions are welcome.

Whats Your Eye-Q?

The American Optometric Association published the results from their 5th annual Eye-Q Survey. The survey asks men and women all sorts of questions about their eye health including allergies, UV protection, nutrition, and aging. Interestingly, men and women didn't always see eye to eye (yes, pun intended).

Check out this year's Eye-Q Survey Results here.

Take a simple Eye-Q Test for yourself!

Grade yourself as follows: 19-20, I understand my eyes very well; 17-18, my view of my eyes is pretty clear; 15-16, my concept of my eyes is a little fuzzy; 13-14, the way I see my eyes could use a little correcting; and 12 or under, my eyes need much more understanding.

True	False	Questions
		1. At a distance of ten inches, my eyes can detect an object as small as four thousandths of an inch in size.
		2. My eyes can distinguish only four colors.
		3. My eyes can see a candle 14 miles away.
		4. Ten percent of what I know comes through my eyes.
		5. Reading in dim light can put a strain on my eyes.
		6. When viewing the TV, I should sit a distance equal to twice the width of the screen.
		7. A lack of vitamin A in my diet can cause reduced night vision.
		8. Dilation of the pupils allows my doctor to see a better view of the inside of my eyes.
		9. The best color for sunglasses is blue.
		10. Tears contain substances that slow down bacterial growth.
		11. My eyelids work much like a car's windshield wipers.
		12. Sunglasses will allow me to look directly at the sun.
		13. Many prescriptions for eyeglasses are identical.
		14. Smoking can effect my vision.
		15. If I have 20/20 vision, I don't have any eye problems.
		16. Air pollution affects only my lungs and breathing.
		17. If I am nearsighted, I see near objects more clearly than distant ones.
		18. If I am farsighted, I see distant object more clearly than near ones.
		19. Glaucoma is a serious eye disease that can cause blindness.
		20. Regular eye examinations can help protect my eyes and general health.

ANSWERS: 1.T. 2.F. 3.T. 4.F. 5.F. 6.F. 7.T. 8.T. 9.F. 10.T. 11.T. 12.F. 13.F. 14.T. 15.F. 16.F. 17.T. 18.T. 19.T. 20.T.

Why Aren't My Eyes Blue?

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What determines a person's eye colour?

Genetics play a important role. However, determining the combination of genes and chromosomes is very complicated and random mutations happen quite often.

The main factors that determines the colour of a person's eyes are:

• The amount of melanin (a dark pigment), which is determined by the number of melanocytes (cells that make the pigment) in the iris (coloured part of the eye)
• Presence of some other less common pigments in the iris
  
• Deposits of proteins in the iris
• All of these come together and affect the way light is scattered and absorbed at the front of the eye

For this reason darker-skinned people generally have darker coloured eyes and lighter-skinned people have lighter eyes.

FAQ:
Q: Is it possible for eyes to change colour?
A: Yes. But it would most likely happen early in life. Babies can be born with a low amount of melanocytes which slowly increases with age.

Q: Can I change my eye colour?
A: Yes, with contact lenses :-)

Q: Is it possible to have two different coloured eyes?
A: Yes. It's called heterochromia. Its also possible to have different parts of the same iris be different colours. This is partially genetic and partially the way the pigment is dispersed.

Q: Are there any medical implications to eye colour?
A: Yes. Lighter eyes tend to be at higher risk for Age-Related Macular Degeneration and ocular cancers. Likely due to some protective effects of pigment.

Q: Why do you keep spelling colour with the letter "U" in it?
A: Because I am a British Canadian.

Thanks for reading. Your questions, comments, and suggestions are always very welcome. Please feel free to pass this info on to anyone who may be interested.

The Eye Exam - Why Is It So Important?

Remember, this info plus much more is available on my Facebook and Twitter pages.


Everyone knows that your Optometrist is the person to see for your glasses and contact lens prescriptions. But, the health portion of the exam is often overlooked by patients.

There are many, many ocular and systemic conditions that can be detected and followed by your Optometrist with regular eye exams. Here is a short list of some of the more important/common conditions:

• Glaucoma
• Cataracts
• Macular degeneration
• Retinal detachments
• Retinal holes and tears (common in highly near-sighted patients)
• Bacterial and viral infections
• Eye turns and lazy eyes
• Colour deficiencies
• Stereopsis (our ability to see 3D)

• Diabetes
• High blood pressure
• High cholesterol
• Thyroid problems
• Inflammatory conditions such as: colitis, Crohn's disease, rheumatoid arthritis, psoriasis
• Vitamin deficiencies
• Brain tumors
• Nerve problems in the eye and brain
• Stroke
• Blocked arteries in the neck and head
• HIV/AIDS
• And many more...

Thanks for reading. Any and all feedback, questions and comments are always welcome. Please feel free to pass this information on to anyone who may be interested.

Diabetes and the Eye

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Diabetes is a disease that has grown and spread exponentially in the last 20 years, reaching epidemic proportions. Yet, many people do not know how devastating it can be and the effects it can have on the eye.

Background:

There are 2 main types of diabetes:

• Type 1 (Insulin dependent):
• Early onset (usually by teenage years)
• Autoimmune disease - the body attacks itself and causes destruction of the cells that make insulin
• Insulin is the chemical which promotes uptake of sugars from the blood into muscle and other tissues
• Treated with insulin replacement
• Can lead to death if not treated

• Type 2 (Non-insulin dependent):
• Later onset (usually over the age of 40)
• Body tissues develop resistance to insulin
• Very commonly associated with sedentary lifestyle, high fat diets, and obesity (No surprise its huge in North America!)
• Treatment:
• Early/mild: weight loss, diet changes, and exercise
• Moderate: All of the above plus oral meds that encourage glucose uptake
• Severe: All of the above plus insulin
• Significantly increases risk of heart attack, stroke, and kidney failure

The end result for both, if not well controlled, is high sugar (glucose) levels in the blood stream.

Normal blood sugar levels:

• Healthy patients should have glucose levels of approx 4 mM
• Diabetic patients are instructed to try to maintain them below 6 mM
• Uncontrolled diabetics often have glucose levels of 15-20 mM (if not higher)
  

The Eye:
While high sugar levels in the blood can affect the structure and function of cells and chemicals, the main concern in the eye is loss of integrity of the blood vessel walls.

The tiny retinal blood vessels can become leaky, thus allowing fluid, blood, and proteins to seep into the retina. If left uncontrolled, this can result in any combination of the following:

• Diabetic retinopathy:
• bleeding in the back of the eye, including leakage into the vitreous gel thus causing loss of vision
• lack of blood and oxygen delivery to areas of the retina
• death of retinal tissue - permanent loss of vision
• development of new, weaker blood vessels (neovascularization) which can cause further leaking and fibrosis of the retina
• Macular edema
  
• swelling of the macula (central part of retina) causing decrease of vision
• Retinal detachment:
• Fluid leakage behind the retina or fibrosis due to new blood vessels causing it to be pulled away
• Neovascular glaucoma:
• Due to the lack of oxygen delivery, new blood vessels begin to grow at the front of the eye and block the drainage of fluid causing increased pressure in the eye which can result in damage to the optic nerve - yet another way to cause vision loss
  

If the diabetes is adequately treated, some of the milder problems can be reversed and vision may be restored.

If you have diabetes, or know someone who does, it is very important to keep in mind the effect it can have on your eyes. Regular, annual eye exams are imperative and are no less than the standard of care of diabetic patients.

If there are any questions please feel free to ask. And as usual, please forward this information on to anyone who may find it useful.

Thanks for reading.

 

What does 20/20 mean?

This week's topic is something I get asked almost everyday. Unfortunately, the answer is never as simple as it may seem. I will do my best to explain it here.

Simple definition: 20/20 is the size of letter that the average person should be able to see when fully corrected (assuming that there are no visual opacities or retinal problems). It is what we aim to achieve when correcting patients with contact lenses, glasses, and laser surgery.

More specifically: A 20/20 letter is exactly 8.726mm in height at a distance of 20 feet.

FAQ:
Q: Does 20/20 mean "perfect vision"?
A: No, this is a common misconception. There really isn't such a thing as perfect vision. The sharpest estimated human visual acuity is about 20/8. Which, with a little math, equates to a minuscule 3.49mm letter at 20 feet!

Q: How is the size of the letter determined?
A: The letter size for 20/20 is based on the average spacing of the light-sensing cells in the retina, thus the average eye's ability to discern spaces between letters

Q: Why 20 feet?
A: That is the approximate distance at which the internal focusing system of the eye (used for near vision) is relaxed thus allowing your eyes to effectively see into the distance.

Q: What if I can't see any of the letters without my glasses? Does that mean I'm Legally Blind?
A: Vision without correction does not really provide any significant information about your eyes (other than the fact that correction may be needed).
The definition of Legal Blindness in Canada and USA is 20/200 in the better eye with correction. Thats 10 times the size of a 20/20 letter.

Q: Do I need to see 20/20 to drive?
A: No. This may come as a surprise. But, the legal requirement for driving is 20/40 in one eye. That's double the size of a 20/20.


Thanks for reading. Please feel free to pass this info on to anyone who may find it useful and don't hesitate to send me your questions and comments.

Mirko Cro Cop suffers serious eye injury

In recent days, while training for his heavyweight bout against Frank Mir at UFC 119, Mirko Cro Cop suffered a significant injury to his right eye. The picture below shows a gruesome image of what must a very painful eye.

MiddleEasy.com has an interview with UFC President Dana White discussing Cro Cop's situation. You'll see Dana mentions the doctors told him that the eye heals faster that any other part of the body. This is partially true. The cornea and the outer covering of the eye ball, the conjunctiva, heal very quickly (usually, a scratch or cut will heal within hours to a couple of days).

A corneal abrasion wouldn't lead to bleeding like you see in this image, so my guess would be a conjunctival laceration. Mirko was seen by multiple opthalmologists and cleared to fight at this weekend's event. For a guy like Cro Cop, its just a love tap :)

Laser Eye Surgery

Laser procedures are commonly used to treat refractive errors (ie. near- or far-sightedness and astigmatism), with the end goal of providing the patient with clear vision without glasses or contact lenses.

There are 2 major types of Laser Refractive Surgery. While the process is a little different, they both essentially flatten the cornea (for near-sighted) or steepen it (for far-sighted):

LASIK - Laser-ASsisted In-situ Keratomileusis

• The more recent of the 2 procedures
• Most common due to shorter recovery period after surgery (not necessarily better results)
• Requires the surgeon to make a thin "flap" of the surface of the cornea before using the laser
• The flap is replaced after the the surgery - effectively producing a natural bandage for the eye

PRK - PhotoRefractive Keratecomy

• The older of the two procedures
• Less common of the two due to longer healing period
• Still produces accurate results
• Usually used for patients with thinner corneas (not enough thickness to form flap before using laser)

FAQ:
Q: Do I still need to have regular eye exams if I can see perfectly after my surgery?
A: YES YES YES!!! Patients who have had laser surgery need regular eye exams more than the average population! Firstly, they have had surgery. Next, the majority of patients that have these procedures are near-sighted and the primary cause of near-sightedness is an increased length of the eye. This causes stretching of internal structures (such as the retina) and leaves these patients with a higher risk for retinal detachments. This does not change just because they no longer have to wear glasses!

Q: Is it safe?
A: Yes. The surgeons that do these procedures, do hundreds to thousands per year. Technology is improving daily to provide more accurate results. Complications occur in less than 0.5% of patients.

Q: Is my prescription too high?
A: Most likely not. Refractive errors as high as -12.00 can be successfully treated. Tiger Woods and Roberto Luongo were about -10.00 and -11.00 respectively before having their surgeries.

Q: What are the common side effects or complications?
A: The number one post-operative complaint is dry eyes. Halos around lights, decreased night vision, sensitivity to light, and recurrence of prescription are also well documented. Most surgeries are guaranteed for 5-10 years. After which, it is possible the patient will require glasses again or a "touch up" surgery.

Q: What are the alternatives?
A: Intacs and Ortho-K are 2 possible options. Intacs are very small corneal implants that create the same effect as laser surgery of flattening the cornea. Ortho-K are contacts that you wear while you sleep. Again, these have the effect of flattening the cornea. In the morning, you take them out and don't need to wear any glasses or contacts during the day. The benefits of these 2 alternatives is that they are both fully reversible. These are limited to lower prescriptions of approximately -1.00 to -4.00.

Thank you for reading. I hope you found this information useful. Please feel free to contact me with questions and comments.

Find me at Facebook.com/HarbirSianOD and Twitter/HarbirSianOD!

Why Rubbing Your Eyes is Bad for You

Everyone knows you're not supposed to. But why?

• Short-term:
• Rubbing your eyes when they're itchy or irritated can cause break down of the cells within the eyelids and on the surface of the eye ball. This releases more histamines which make the itchiness worse.
• Also, rubbing can cause breakage of small blood vessels in the eyelids which can result in dark circles forming around your eyes

• Long-term:
• consistent long-term rubbing of the eyes, especially in kids, can potentially lead to a condition called keratoconus
• Keratoconus is a condition where the front surface of the eye (the cornea) becomes thinner and thus loses its shape. This results in blurry vision for the patient, which cannot always be fully corrected with glasses or contact lenses.

Are Carrots Good for Your Eyes??

The answer is "Yes... However..."

• Carrots are high in Beta Carotene, which our body converts to Vitamin A
• Vitamin A is very important for the health of your eyes, helping the retina function more efficiently

However...

• Eating lots of carrots will not change/improve your glasses prescription

Find me at Facebook.com/HarbirSianOD and Twitter.com/HarbirSianOD for more info!

As usual, questions, comments, and suggestions are welcome.

The Dreaded Air Puff Test

Almost everyone who has seen an Optometrist recently has had to endure the excruciating agony of a "gentle puff of air" to their eyes. But why?!

• Purpose:
• A screening test for glaucoma
• Measures the pressure inside your eyeball
• Increased pressure inside the eye can lead to glaucoma

• Technical term for the air puff is Non-Contact Tonometry

FAQ:
Q: Does it make a difference if I'm a fidgety Nancy? And is there an alternative test?
A: Yes and yes, Nancy! Movement can affect results. The alternative involves a drop of anesthetic and small plastic probe touching the front of your eye. This is actually the most accurate method.

Q: What is a normal pressure reading?
A: The normal range is 10 to 20

Q: What is Glaucoma?
A: Damage to the Optic Nerve often due to high pressure inside the eye compressing nerve fibers. Causes vision loss, usually starting with peripheral vision.

Q: How do I know if I have Glaucoma?
A: It is important to know the risk factors: age over 50, family history, and high intra-ocular pressure. But the only way to know is to visit your eye doctor.

Questions and comments are always welcome. Please feel free to forward this information to anyone who may find it useful.

Color Blindness

• Most people have heard of Rods and Cones in our eyes

• Cones are for color and Rods are for night vision
• There are 3 kinds of Cones: red, green, and blue
• Cones don't actually sense color, they sense wavelengths of light and these are translated by the brain in to colors

• Its actually very rare for a person to be color "blind" (unable to see colors)
• More commonly people have a color "deficiency"

• This means that one type of cones is not sensing the correct wavelength
• This result in confusion between colors

 

FAQ about Color Blindness:

Q: What is the most common color deficiency?

A: Green deficiency (medical term: Deuteranomoly) is most common. This results in difficulty with greens, reds, and mixtures of these colors.

 

Q: Is it more common in men or women?

A: Men! 8% of men have color deficiency compared to only 0.5% of women.

 

Q: How do I know if I have a color deficiency?
A: If you have difficulty distinguishing between greens, reds, or mixtures of these. Take a quick test by looking at the attached image one eye at a time. If you miss more than 2, you may have a color deficiency.

As usual, all questions and comments are greatly appreciated and feel free to pass this info on to anyone who may be interested.