Common Eye Questions

What eye drops should I use for pink eye?

There are three main types of conjunctivitis, or “pink eye,” as it is commonly known: viral, bacterial, and allergic, and this post focuses on the best eye drops, or treatment, for each.

Pink eye can be due to viruses, bacteria, or allergies.

Pink eye can be due to viruses, bacteria, or allergies.

Viral Pink Eye

Caused by the same viruses that can also cause the common cold — most commonly, adenovirus — viral pink eye can be a real bugger. Importantly, there are no good eye drops for treating viral pink eye.

Antibiotic eye drops won’t work, since those treat bacteria. And “get the red out” eye drops like Visine are no good either, because your eye will quickly become habituated to the tetrahydrozoline in the Visine. Tetrahydrozoline (and naphazoline, the ingredient in other, similar eye drops) are vasoconstrictors, which cause the blood vessels on the surface of the eye to constrict, so the eye appears less pink.

Sounds great, right? Well, the problem is those blood vessels become “addicted” to the medication, and when you stop using the Visine a couple of days later, you get rebound hyperemia — the blood vessels, now deprived of the medication, swell to larger than ever, making your eyes even more red and irritated than before. Visine, or other “red eye” eye drops, are never a good idea.

Bacterial Pink Eye

Fortunately, for pink eye that is caused by a bacterial infection, there are many wonderful options for eye drops. If your doctor diagnoses bacterial conjunctivitis, he or she may prescribe eye drops such as ofloxacin or polytrim, or an ointment like erythromycin. True bacterial conjunctivitis should resolve within a day or two of starting antibiotic eye drops. If it doesn’t, it’s likely not bacterial.

Allergic Pink Eye

Pink eye that is accompanied by itchy, watery eyes is often due to allergies to something in the environment. It’s easy to treat with over-the-counter ketotifen eye drops. Cold compresses can help too. Oral antihistamines can also be helpful.

For more information about pink eye, including signs and symptoms, as well as red flags, read this article.

Isn't strabismus just a cosmetic problem?

Strabismus is more than just an aesthetic issue, as it can interfere with visual development in childhood.

Strabismus is more than just an aesthetic issue, as it can interfere with visual development in childhood.

This is a common question. The short answer is "No!" Want the the longer answer? Here are five reasons why:

  1. Strabismus, or eye misalignment, in children can cause amblyopia, or poor visual development, in the eye that isn't straight. This can be so severe as to cause permanent, severe vision loss. Fortunately, if detected, it can be treated effectively and reversed.
  2. Strabismus in children can prevent the natural development of something called "binocular fusion," a process in which the eyes learn to work together, so to speak. In the first year or two of life, the neural connections between the eyes and the brain are rapidly developing, and the brain learns to put the images produced by both eyes -- images which are similar, but not identical -- into one single image. This process allows us to develop depth perception. Strabismus very commonly inhibits this.
  3. Strabismus in adults typically causes diplopia, or double vision. It's easy to understand why: if the eyes are looking in different directions, they will produce different images, which the adult brain will see as double images. Want to know what that's like? Cross your eyes and walk around for a few minutes. It's decidedly unpleasant!
  4. Strabismus surgery, because it is not cosmetic, is covered by medical insurance.
  5. Strabismus in our society is unfairly associated with things like reduced intelligence and diminished potential for success in the workplace. Below is a review of the scientific literature on the negative societal implications of strabismus:
  • A 2001 study published in the Journal of the American Association for Pediatric Ophthalmology and strabismus allowed children to play with "normal" dolls and dolls that had been made to have strabismus. They were questioned after 10 minutes of play. Grade-school children were 73 times more likely to express a negative bias toward the dolls with strabismus. PubMed link
  • A 2003 study published in Acta Ophthalmologica Scandinavica showed photographs of the same children with and without strabismus to 30 elementary school teachers. Kids with strabismus were considered by teachers to be more unhealthy, less hard-working, and less happy. They were also felt to be less likely to be accepted by their peers and more likely to have difficulty learning. PubMed link
  • A 2000 study published in Ophthalmology showed photos of the same job applicants, both with and without strabismus, to potential employers. Women with strabismus were less likely to be considered for the job compared to women without strabismus. Strangely, this unfair bias was not seen toward men with strabismus. PubMed link
  • A 2008 study published in the British Journal of Ophthalmology interviewed 40 dating service agents, and 92.5% of them felt that a client having strabismus would make it more difficult to find a partner. Among facial disfigurements, only very prominent acne or a missing tooth had a greater negative impact. PubMed link
  • A 1993 study published in the Archives of Ophthalmology interviewed 43 teens and adults that had strabismus in childhood which was not corrected. Over 1/3 of them reported that their friendships had been moderately to severely affected, particularly friendships with the opposite sex. 84% reported that their strabismus interfered with school, work, and/or sports. Sadly, 50% said they had experienced ridicule or abuse because of their eye misalignment. The majority said it had a negative impact on their self image, and 1/3 made some attempt to hide their strabismus, with their hair, head position, or sunglasses. PubMed link

In sum, strabismus is much more than just a cosmetic problem. It has a significant impact on people's vision and quality of life. And it can be fixed! Helping patients fix their strabismus is one of the most gratifying parts of my job.

What do you think? Have you had strabismus and realized it's much more than a cosmetic issue? Have you treated patients who had been told previously that this was the case?

Special thanks to Dr. Scott Larson, MD, for compiling these scientific papers. Dr. Larson, a mentor and friend, is a pediatric ophthalmologist at the University of Iowa. His excellent website can be found here.

Will wearing glasses fix it?

Wearing glasses helps fix some eye problems, but certainly not all of them.

Wearing glasses helps fix some eye problems, but certainly not all of them.

There is a common misconception that any eye problem can be fixed by wearing the proper glasses. This, unfortunately, is not true. Glasses and contact lenses help correct eye problems related to focus, and that's it.

Think of the eye as a camera. If the camera is out of focus, then it won't take a good picture. Focus the camera (or wear glasses, in our analogy), and you'll have a clear image.

Extending the analogy, here are a few categories of eye problems that cannot be fixed by wearing glasses:

Cataract (lens smudged)
Corneal disease (cloudy screen)
Optic nerve disease (dead battery)
Retinal disease (bad film)

What is this thing?

A phoropter is used to measure refractive error.

A phoropter is used to measure refractive error.

The device you see pictured here -- from the cover of Justin Timberlake's 2013 album "The 20/20 Experience" -- is called a phoropter.

Used primarily to help determine a patient's glasses/contact lens prescription, it has been around for over 100 years. It contains dozens of different lenses which can correct for hyperopia, myopia, or astigmatism. With you seated comfortably, with both eyes open, and your forehead up against the back of the phoropter, the eye doctor will show you an eye chart and check each eye individually with different combinations of lenses. He or she will ask you which is sharper: #1, #2, or if they are the same. The goal is to find two options that appear the same to you in terms of clarity/sharpness. Based on the results, a prescription for eyeglasses or contact lenses can be issued.

What is astigmatism?

Astigmatism occurs when the focusing structures of the eye -- the cornea and lens -- are not perfectly round.

Astigmatism occurs when the focusing structures of the eye -- the cornea and lens -- are not perfectly round.

I get this question a lot, and since it's often misunderstood, I thought it would be a great topic to discuss.

Astigmatism, along with the previously-discussed entities of hyperopia (farsightedness) and myopia (nearsightedness), is one of three common types of refractive error. Refractive errors are problems with the focusing system of the eyes.

A normal eye is round, like the baseball you see here. An eye with astigmatism, by contrast, has a cornea -- the clear, front part of the eye that focuses light -- that is steeper/more curved in one axis and flatter in the axis 90 degrees away, like a football. This means that light in an eye with astigmatism is focused at two different points on the retina, creating a blurry image.

Astigmatism, like all refractive errors, can be corrected with glasses, contact lenses, or laser surgery (e.g. LASIK). It is easy to identify in a routine eye examination.

What does it mean to be "farsighted?"

The anatomy of hyperopia, or farsightedness

The anatomy of hyperopia, or farsightedness

In the simplest of terms, people who are farsighted have an easier time seeing far away than up close.

Why is this? Well, a farsighted eye is an eye that is either too short or too weak. Take a look at this picture. The image is focused behind the retina, not right on the retina where it will be sharpest. You can imagine that this could happen either because the eye is too small, or the focusing power is too weak.

Now, here is where hyperopia is a bit different from simply the opposite of myopia. Young people have the ability to accommodate -- to increase the power of their lens focus -- and this can neutralize farsightedness. Hence, a young person who is farsighted may have no trouble at all seeing far away or up close, even if their prescription is high, because there lens can change shape and focus the image. The natural decline of this ability with age is called presbyopia, and is the reason why many people need reading glasses beginning in their 40s and 50s.

If a person's hyperopia is significant enough to warrant correction, the available options are the same as those we discussed last time, for myopia, namely: glasses, contact lenses, and corrective surgery.

What does it mean to be "nearsighted?"

Anatomical diagram illustrating myopia, or nearsightedness

Anatomical diagram illustrating myopia, or nearsightedness

First of all, myopia, or nearsightedness, means that relatively speaking, you see things better up close than far away. This is easy to remember, because the term "nearsightedness" suggests that you are best "sighted" at "near."

Take a look at the drawing here, of a myopic eye. Ideally, the cornea and lens at the front of the eye (left side of the drawing) should focus the light rays, from the image the eye is trying to see, right on the retina, at the back of the eye (right side). But look at this eye -- the image is focused in front of the retina. Nearsightedness! The eye is either too strong in its focusing ability or too long for its focal power.

So how can this be corrected? One way is by moving the object you look at closer to your eye. Why does this work? Simple optics. As the distance from the object to your eye decreases, the distance from the front of the eye to the image created by the eye increases -- the focal plane "moves backward." This means that instead of being focused in front of the retina, the image will be in focus farther back -- ideally, right on the retina. The more nearsighted you are, the closer this distance between the object you are looking at and your eye will need to be for you to see best.

OK, Dr. Weed, holding things close might work for books and whatnot, but it's not so great for sporting events, oncoming cars, other humans, etc. How else can nearsightedness be corrected? There are a variety of medical and surgical options. By wearing corrective lenses -- eyeglasses or contact lenses -- that "push the image back," so to speak, the eye can then focus images on its retina. Alternatively, a variety of surgical options, most commonly laser vision correction (e.g. LASIK), can be pursued.

Why do stars disappear when I look directly at them?

Stars disappear when you look directly at them because of the anatomy of the photoreceptors in your retina.

Stars disappear when you look directly at them because of the anatomy of the photoreceptors in your retina.

We all have two types of light-sensing cells in our eyes, the rods and the cones. Cones see fine detail and color. Rods see better in dim light. When you look right at something that is small or far away, the image falls on a part of your retina where there are only cones. This means that if you're in a well-lit environment, you will see this object very well. If however you are in dim light, you'll see the object better out of your peripheral vision (looking just off to the side of your target) because then the image will fall on the part of your retina that has rods, which can see in dim light. This is true of everyone's eyes, but many people have never noticed it. There are a few VERY rare conditions that can exaggerate this phenomenon, but they are like 1 in 10,000 level rare. A dilated eye exam could detect them.