Color Blindness

Color blindness is a condition that affects the way a person distinguishes two or more colors, most commonly red and green. It is also possible to lack the ability to distinguish any type of color, though this is very rare.

CAUSES

The most common cause of color blindness is a problem in the development of the color-sensing ability in nerve cells of the eye, called cones. Cones are found in the retina, which is the layer of tissue at the back of the eye on which light is focused. 

This problem is most commonly inherited from mutations on the X chromosome. Because of that genetic location, color blindness is more common in men than in women (who have two X chromosomes and a higher likelihood of having at least one that is sufficient to provide normal color vision). 

Other causes include accidents or trauma, side effects from certain types of medication, and damage to the retina.

DIAGNOSIS

The Ishihara Color Test is the most common way to diagnosis color deficiencies. It is a series of pictures made up of colored spots with a figure embedded in it as a slightly different color. The figure can be seen with normal color vision, but not with a particular color defect. 

In this picture, the number 74 should be visible to people with normal color vision. Viewers with certain deficiencies may see it as 21, and others with more drastic color blindness may not see any number at all. 

TREATMENT

There is no treatment to cure color blindness. People who suffer from color blindness have to learn to adapt to the lack of color vision. However, there are strives toward helping color blind people. Check out these apps designed specifically for people with color deficiencies.

Importance of Sunglasses

From an eye health (and fashion!) standpoint, the right sunglasses are very important. With warm weather on the way, it’s the perfect time to make sure you have a good pair ready and available for your springtime excursions. 

Reasons to Wear Sunglasses:

1. UV Protection: Being outside exposes you to UV radiation from the sun.  UV on your eyes can cause cataracts to worsen, and can cause other eye conditions. Hats and caps can help block some of these rays, but sunglasses offer much more protection. Be sure the ones you buy say that they block 99 to 100 percent of both UVA and UVB. 

2. Skin Cancer Protection: Getting skin cancer on your eyelids and the tender skin around your eyes may be more common than you think. Wearing sunglasses can help protect you against this risk. 

3. Better Vision: The sun is really bright! Wearing sunglasses allows you to see more clearly, which is especially important when doing something like driving a car or boat. Avoid the squinting and watering associated with exposure to very bring sunlight. Sunglasses may also help you avoid a headache associated with prolonged time in bright sunlight. 

4. Protection from Debris: When you are outside, you are vulnerable to dust and debris in the wind. Wearing sunglasses can help prevent getting something in your eye, which could cause a painful corneal abrasion. 

Dominant Eye Test

How to determine which eye is dominant:

1.Hold both arms straight out in front of you, overlapping your hands to create a small hole       between your thumbs and forefingers.

2.Choose a small object, like a doorknob, to focus on. With both eyes open, focus on this object through the hole.

3.Keeping your head and arms still, and still focusing on your object, close one eye. Then close the other. 

4.With one eye open, the object will remain in the middle of your hole. This is your dominant eye. With the other eye open, the object will jump to the side or disappear from the hole. This is your non-dominant eye.

Eye dominance is important for many people, such as people who participate in sports which require aim. It is also important when considering monovision or eye surgery. Interestingly, hand-dominance does not correlate with eye-dominance. Also, most people automatically use their dominant eye when looking through a camera or microscope.

Why We Check Intraocular Pressure

At Carolina Ophthalmology, we check intraocular pressure (IOP) at all regular eye exams. Checking IOP is a very important way to screen for Glaucoma.

Glaucoma is a chronic disease that affects both eyes, and is the second commonest form of blindness, affecting about 1.6 million people in the United States. Known as the “silent thief of sight,” glaucoma can cause slow, painless, progressive loss of vision. Untreated, high IOP damages the optic nerve and causes vision loss. Many patients experiencing slow loss of peripheral vision don’t notice that it’s happening, and once that damage has occurred it cannot be undone. To read more about Glaucoma, click here.

Due to the lack of noticeable symptoms, early detection through routine screenings is important. This preventative measure allows for early diagnosis and treatment before irreversible damage occurs.

Checking IOP is one way to screen for Glaucoma, and is done along with a dilated exam so the doctor can look at the optic nerve, photographs of the optic nerve, and a visual field test to determine if vision loss has occurred.

There are many ways to check a patient’s IOP, including the dreaded puff-of-air test. We use a more accurate, less terrible test called applanation tonometry (blue-light test). This test involves a Goldmann Tonometer attached to a slit lamp which measures the force required to flatten (applanate) a small segment of the central cornea.

First, the technician will put a drop into your eye that is a numbing agent mixed with fluorescein.  The eye is completely numbed and the patient does not feel the prism touch his or her eye. The fluorescein in the drop causes the eye to glow yellow under the blue light of the tonometer. Next, the technician looks through the instrument and adjusts the pressure of the applanator until it matches the pressure inside the eye. This number is the patient’s IOP.

Most normal eyes have IOP between 10 and 20. However, some eyes cannot tolerate even these normal pressures, and others can have higher pressures than these without damage. Patients with high IOP, or with a family history of Glaucoma, should be closely monitored. Due to the damaging effects of Glaucoma, early detection and effective control of IOP through prescription drops is vital to preserving vision.

Call us today to schedule an eye exam and have your IOP checked at 919.967.4836. 

What is Astigmatism

Astigmatism is a refractive error caused by a non-spherical surface of the cornea or lens. Normal (non-astigmatic) eyes have a spherical cornea, like a basketball. Eyes with astigmatism have non-spherical corneas and are torodial, like a football. This means that the surface is more curved in one direction than it is in the direction 90° away. An eye with uncorrected astigmatism cannot refract focal points on the retina; it instead refracts two foci, one horizontal and one vertical, on or near the retina.

Astigmatism can be corrected through glasses, contact lenses, or surgery.  The most common way to correct astigmatism is with spherocylinders used in glasses or contact lenses. The most common directions for astigmatic correction are at the vertical meridian (90°) and the horizontal meridian (180°).

One way to tell if you have astigmatism is to look at your glasses or contacts prescription. If your prescription includes only one number per eye, a spherical number, than your lenses are not correcting for astigmatism. However, if your prescription has three numbers per eye, a spherical number, a cylindrical number, and an axis number, than your lenses do correct for astigmatism. You can tell how much astigmatism based on how far the cylindrical number is from zero. The farther it is, the more astigmatism it corrects for. 

Femtosecond Laser in Cataract Surgery

Carolina Ophthalmology is proud to offer the most advanced technology available for cataract surgery: the Femtosecond laser. Dr. Bryan recommends this cutting-edge bladeless approach to all patients who are good candidates for it. 

Using the laser for some of the most difficult steps of cataract surgery allows for more precision, accuracy, and customization for each patient. Each step is more reproducible and predictable, providing better results both during the surgery and in recovery.

During the surgery, the laser makes it easier to achieve optimal lens positioning. It also provides real-time imaging so Dr. Bryan can see detailed and specific maps of the patient's eye while performing surgery. The laser also offers more specific customization to each individual eye through an integrated OCT.  This customization extends to lens fragmentation as well as size, shape, depth, and location of each incision.

Laser cataract surgery offers the most advanced astigmatism correction available which could lessen dependency on glasses after surgery. 

If you are thinking about having cataract surgery, call us today for more information. Find out how cataract surgery, and cataract surgery with the Femtosecond laser, can improve both your vision and your life. Call us at 919.967.4836 to schedule an evaluation. 

My LASIK Experience

In my glasses before LASIK

BEFORE LASIK

Having worn glasses or contacts all of every day since the third grade, I always thought the idea of LASIK surgery was kind of miraculous. My first week of working at Carolina Ophthalmology, I heard countless examples of ways LASIK had improved patients lives: People could see to get up in the middle of the night, could swim in the ocean without dealing with salty contacts, and could travel without messing with all the accoutrements required for vision correction.

So, I had a consultation and it turned out I was a great candidate for LASIK surgery. I waited about ten months to decide to go for it (I was nervous and it just never seemed like the right time.) Now that I’m on the other side looking back, I can’t believe it took me

that long to go for it. I’m thrilled with the results and wish I had been enjoying the freedom all along.

HAVING LASIK

The morning of my LASIK surgery, I was split between nervousness and excitement. The first step was the WaveScan measurements. I sat in front of a machine that mapped my eye and produced the numbers that would be plugged into the laser.

At the WaveScan with Jeanette

Once I got into the OR, Dr. Bryan explained everything that was about to happen. After he got me prepped, the IntraLase laser cut the flaps in my corneas that would be lifted up, corrected under, and placed back down. Dr. Bryan put a suction ring on my eye and I felt some pressure. It was the same feeling as pressing the heel of your palm against your eyelid -- dark and sort of speckled vision, but no pain. Each flap was cut in 20 seconds and all I had to do was lie still.

Next, Dr. Bryan lifted my flaps up one at a time. During this part there were bright lights and I could tell that he was moving something on my eye, but I felt nothing and it wasn’t painful or unpleasant, just strange.

The laser that actually does the correction came next. Everything was dark except for a flashing orange light for me to look at. When it was time to start the surgery, they told me exactly how many seconds it would be, 24 for my right and 25 for my left, so I would know how long to expect it to last. I couldn’t see or feel the laser, but I could hear it ticking the whole time. It was over before I knew it.

All the things I was worried about went fine: My lids were held open so I couldn’t possibly blink, my eyes were numb so I didn’t feel like I needed to blink anyway, I felt no pain, and I knew that the cameras tracking me would shut the laser off if I moved at all.

Twenty-five minutes later, I was walking out of the O.R. My vision wasn’t perfect, but it was much better than it had been before surgery. It was sort of like I was looking through Saran Wrap. I was ready go home and take a nap.

Dr. Bryan and me after surgery

AFTER LASIK 
When I got home the main thing that I noticed what that I was very light sensitive and my eyes were watering a lot. They didn’t hurt or feel scratchy at all.

After I slept for about an hour, my eyes were feeling better. I put drops in every two hours and spent the rest of the afternoon resting.

By that night I was back to normal except for some dryness and some redness. I slept in the plastic goggles so I wouldn’t accidently rub my eyes in the night, but I had no problem falling asleep.

The day after my surgery I was 20/20 in both eyes and I had no trouble coming to work. By six days out from my surgery, I was 20/15.

If you’re thinking about having LASIK, please call to ask questions and to schedule a free consultation appointment. What do you have to lose? Start living your post-LASIK life now, I know I’m enjoying mine.

—Laura, Refractive Surgery Coordinator 919.945.3937