Eye color – Did you know?

1) How is eye color determined?

   Eye color is determined by two distinct factors.

• The pigmentation of the eye’s iris – The iris is a muscle and the colored part of the eye. The amount of melanin present determines eye color.
•  The scattering of light in the stroma of the iris – Rayleigh scattering is a similar phenomenon that accounts for the blueness of the sky. Blue and green pigments are not present in the iris of humans or ocular fluid.

2) Does eye color change with age?

Photo courtesy of Javier Manso on Flickr

• Yes. Most babies with European ancestry have light-colored eyes before the age of one. As a child grows, melanocytes produce melanin. Melanocytes are cells found within the iris of human eyes. Most eye color changes occur when the child is around one year old, however it can happen up to three years of age.
• Eye color (lightening or darkening) may change with age. This occurs in 10 to 15 percent of the population. However, if your eye color changes dramatically as an adult, it is important to schedule an examination with your eye doctor. Eye color changes may indicate certain diseases, such as Fuch’s heterochromic iridocyclitis, Horner’s syndrome or pigmentary glaucoma.

 3) Is it possible to see emotions such as anger or love in the eyes?

Yes. Certain emotions can change both the pupil size and the iris color. Pupil size gets larger in dimmer lighting and smaller in brighter lighting. When pupil size changes, pigment in the iris compress or spread apart, which can change the eye color.

4) What makes eyes green?

The color of green eyes is not a result of iris pigmentation. Green eyes are due to a combination of amber or light brown pigmentation of the stroma. There is a low or moderate concentration of melanin. The green appearance is due to the Rayleigh scattering of reflected light.

5) What can I do to change my eye color?

Color contact lenses are available if you want to change your eye color. There are even colored contact lenses with patterns for occasions such as Halloween. Since contact lenses are medical devices, visit your doctor of optometry for a contact lens fitting.

~Melissa Barnett, OD, FAAO
California Optometric Association
http://www.coavision.org

Vision and the aging eye

Courtesy of ORBIS US on Flickr

Many patients reach a certain life stage and realize they need to start thinking more about their vision and preventing eye problems.  This usually happens in their early to mid-forties when people notice reading is a lot easier when there’s plenty of light and the print is held further away.  Those who have seen an eye care provider for this problem should have already discovered that this is a normal aging process.  But how does one know when vision changes are normal or should be concerning?

Eye conditions that impact vision:

• Presbyopia is the medical term for when the focusing muscles in the eye are not as flexible, causing poor focusing ability for objects nearby.  This typically occurs in the late thirties/early forties and is easily corrected with reading glasses or bifocal or progressive lenses.
• Cataracts begin to develop in our forties and progress over time.  There is a natural clear crystalline lens in our eye which focuses light onto our retina.  With ultraviolet ray exposure, this lens can become more opaque and yellow over time, causing a dimming of vision and glare and haloes around lights.  The best way to prevent cataracts from progressing quickly is to protect the eyes with UV-blocking sunglasses anytime you are outdoors.  The good news about cataracts is that they can be easily removed and replaced with an artificial lens implant.  With the latest technology of intraocular lens implants such as muiltifocal lenses, patients are now able to see clearly at all distances without the use of glasses or reading glasses.
• Glaucoma is a symptomless eye disease of the optic nerve head where the nerve slowly deteriorates over time.  Most patients who develop glaucoma will not have any symptoms until the late stages of the disease, when peripheral vision deteriorates and patients are left with tunnel vision.  There is no cure or preventative measure for glaucoma, however, it is easily treated with eyedrops.  The only way to determine if you have glaucoma is to have annual comprehensive eye examinations.
  

  Courtesy of Nargopolis on Flickr

• Macular Degeneration is another common eye disease that can cause debilitating vision loss.  This occurs when the macular region of the retina loses its integrity causing poor central vision with distortion or gray spots.  It is often detected upon routine examination, especially when photos of the retina are compared over time.  Fortunately, there have been extensive studies on macular degeneration and the field has changed dramatically over the last several years.  An important test in recent years is genetic testing to determine one’s risk factor for vision loss as a result of macular degeneration, as well as antioxidants that may be useful in reducing this risk.  Clear risk factors include a history of smoking, exposure to ultraviolet radiation, increased cholesterol levels and Caucasian women with lighter eyes and fairer complexions.
• Retinal Detachment tends to occur more often in those who are older than 65.  The retina is a thin and fragile tissue that lines the back wall of the eye and sends visual information to the brain.  This tissue becomes more fragile over time and can easily develop a hole or tear leading to a retinal detachment.  If you experience flashes of light, new floaters, or a change in your vision, you need to be seen right away by your eyecare provider.

There are a myriad of eye conditions that can develop as one ages.  The most important and useful method of preventing vision loss is to stay healthy.  See your primary care physician regularly to evaluate and treat high blood pressure, high cholesterol, diabetes and other health conditions.  If you have uncontrolled health conditions, you can easily lose your vision to diabetic retinopathy, hypertensive retinopathy, or a stroke in the eye.

So, as I tell all my patients, see your physician regularly, eat green leafy vegetables, take your medications, and monitor your own blood pressure or blood sugar.  And of course, wear sunglasses outdoors and see your optometrist annually.

~Cindy P. Wang, OD, FAAO
California Optometric Association
http://www.coavision.org

“What if 1 and 2 look the same?!”

Courtesy of riekhavoc (caughtup?) on Flickr

A common concern for some of my patients is if they don’t tell me the correct choice of lens, then their prescription for that year will be off and not work properly. This is not true. When an optometrist is switching between lenses (which we in “the business” call a refraction), we are fine-tuning a prescription using the patient’s input to find the lenses that are the most clear and comfortable.

Optometrists are trained to filter out incorrect answers from our patients as we double and sometimes triple check on your responses to make sure we have the right powers. Many optometrists do this by bracketing the lens choices presented to patients. Bracketing means we pick two lenses with a noticeable difference in powers and move towards the most clear of the two. By doing so, the lenses in 1 and 2 may end up being the same lens or lenses in choices 7 and 8, etc.

Additionally, when we bracket the lens choices our goal (or “end point”) is when the two choices look just about the same. So if your optometrist is checking your eyes and the two choices look about the same, tell them- that’s what we want to know.

Another thing that we as optometrists don’t want is to give you a glasses prescription that are too strong for you. That is why it is important for you to relax and try not to squint when your optometrist is checking your prescription. If you are constantly squinting when we try to refract you, then you are more likely to end up with glasses that only work well when you squint, but are too strong for you when you don’t.

Courtesy of Lyn Kelley Author on Flickr

Something I have found to help patients give better responses is remembering to blink often. Occasionally, a patient will get so fixated on telling me which lens looks better that they don’t blink as often as they normally would. This can cause your tear film on the surface of your eyes to start to break up and affect your ability to tell which lens looks better. Blinking often lets your eyelids put a smooth layer of tears over the front of your eyes. It is similar to polishing a lens, and a polished lens is always easier to see out of than a scratched lens.

Your optometrist can check on the health and structures of your eyes as well as check the function of your two eyes working together when you go in for your annual eye exam. The art of determining a person’s prescription is not easy, but an optometrist is trained to work with the responses of their patients. Don’t worry about getting it wrong! If you just remember some of the tips mentioned above, you can be sure your optometrist find your proper prescription.

~Ranjeet S. Bajwa OD
California Optometric Association
http://www.coavision.org

The SCARY… and fun truth about colored contact lenses

Colored contact lenses are a popular topic this time of year as many people prepare their Halloween costumes. How fun is it to have a cool accessory like tiger eyes, cat eyes or red or white eyes to complement the most creative of costume? Colored contacts are a great fun option.  There are also many people who like to wear colored contact lenses daily to make their eyes more blue, more green, more brown or a different color all together!

Courtesy of therefromhere on Flickr

However, most people do not realize that even contacts worn for cosmetic purposes still pose a potential health risk for the eye if not properly fitted. This is true even if there is no prescription on the lens.  Contact lenses are classified as “medical devices” with the FDA.  Regardless of a corrective prescription, contacts are plastic on the surface of the eye and need to be fit properly and be taken care of properly to lessen the chance of vision threatening infections such as corneal ulcers.

Doctors of optometry perform additional tests above and beyond the glasses and eye health examinations when fitting contacts. We evaluate the size and shape of the cornea, the health of the tear layer and the fitting relationship between the cornea (the outer surface of the eye where the lens sits) and the contacts lens to insure the safest most appropriate lens for each individual patient.  We also educate patients on the best cleaning and wearing regimen for the them.  This greatly reduces any complications associated with contact lens use.

Buying contact lenses without a doctor’s prescription is something that happens with colored contacts often.  This practice leads to rise in vision threatening conditions that could be prevented with a proper contact lens examination. So, buy a different kind Halloween contact lens for each Halloween party this season, but get a prescription first!

~Lisa Weiss, OD, MEd, FCOVDCalifornia Optometric Association
http://www.coavision.org

Eye-related headaches: the cause and effect

Headaches are no fun and are often debilitating and unnerving.  Many of us have experienced at least one episode of a headache in our life time.  Some of us unfortunately experience weekly if not daily headaches.  This just shouldn’t be.  Some headaches come and go while others seem to get worse and worse.  A knee jerk reaction in all of us is to reach for that bottle of headache pain reliever that we conveniently store in our home medicine cabinet.  While this may temporarily relieve whatever headache type we may be feeling, this may not always be the best treatment choice.

Courtesy of Brandon Koger on Flickr

Did you know that the root cause of many headaches stem from eye-related conditions?  Doctors of optometry routinely address headache concerns, evaluate for eye-related causes of headaches, and prescribe an appropriate course of treatment or further necessary testing.

How can you ready yourself for an appointment with your optometrist?  Be prepared to answer the following 10 questions that your optometrist will likely ask of you regarding your headache.

1. When did your headaches begin?
2. How often do you get these headaches?
3. How long do they last?
4. Where specifically is the headache?
5. Describe the nature of the headache?
6. How intense is the headache on a scale of 1 to 10?
7. Is there anything you do to make the headache worse?
8. Is there anything you do to make the headache better?
9. What medications are you currently taking?
10. Do you have a family member that also suffers from headaches?

Your optometrist will perform a battery of selected in office tests to determine if your headache may be caused by an eye-related source or from some other bodily origin.  Common eye-related headache conditions that your doctor of optometry may consider include but not limited to:

● Uncorrected or undercorrected hyperopia (farsightedness)

● Uncorrected or undercorrected presbyopia

● Accommodative spasm or dysfunction (focusing problems)

● Vergence disorders (eye teaming problems)

● Uveitis (inflammation of the eye)

● Intermittent angle closure glaucoma (acute raise in eye pressure)

Cause and Effect

Uncorrected or undercorrected hyperopia or presbyopia, and accommodative disorders all put an undue amount of stress on the overall focusing system of the eye causing the patient to experience blurry vision and headaches .  When the two eyes do not work in concert in the case of vergence disorders, it wreaks havoc with the muscles in each eye and in how vision is ultimately perceived and processed.  This can also provoke a headache to come on.  If an eye becomes inflamed in uveitis, specific muscles in the eye goes into spasm creating light sensitivity, tearing, eye pain, browache, and headaches.  And last, when the drainage system of the eye intermittently impends the flow of fluids out of the eye with that of intermittent angle closure glaucoma, the eye pressure may acutely spiral up triggering a subsequent browache and headache.

If your optometrist determines that your current headache is not eye related, he or she will recommended that you seek further evaluation and care from your primary care physician if the patient has/is…

● Sudden, abrupt, or split-Second

● New headache sufferer without a previous history

● Progressive headache especially in individuals over 50 years of age

● Long standing headaches sufferer, but the headaches have evolved in its frequency, severity, or nature

Or if the headache is accompanied by…

● Fever, weight loss, night sweats

● Other concurrent health conditions such as cancer and HIV

● Neurologic symptoms such as confusion, impaired alertness / consciousness

A doctor’s order:  Don’t go another day with a nagging headache. Go see your optometrist to get relief, today!

~Judy Tong, OD, FAAO
California Optometric Association
http://www.coavision.org