PAIN FOLLOWING PUPILLARY DILATION

Ophthalmologist Carolina Valdivia, MD answers a question about pain felt after pupillary dilation for an eye examination.

Hi Dr. Valdivia. I had an eye exam today at about 11 in the morning in which the eye doctor put drops in my eyes to dilate the pupils. When I got home around 12:30 pm, I was fine. Now, it is almost 2 pm and I have noticed my eyes are hurting. Is that from straining to look at the computer that I have been on since I got home? They hurt most when I move them. Is this normal?



Thank you for your question and for your interest in glaucoma-eye-info.com.

Let me start with a little background about the eye. Stay with me, you will see why this is relevant in a minute.

The eye functions like a camera. It has the ability to focus on objects both at close range and at a distance. When you use a camera to shoot something close, lenses inside it are combined to increase its focusing power.

The technical term for pupillary dilation is mydriasis. Various medicines are used to induce mydriasis, the most common of which are tropicamide and cyclopentolate. These mydriatic agents cause relaxation of muscle fibers in the iris and in the ciliary muscle.

The ciliary muscle has an important function in accommodation. The reason for this is that the ciliary muscle is directly connected to an array of fibers known as Zonules of Zinn that attach directly to the lens and suspend it inside the eye in line with the pupil. You can learn about where these structures are located by going to the eye anatomy. page.

How does pupillary dilation affect near vision?

The ciliary muscle contracts causing relaxation of the Zonules of Zinn. This results in a thickening of the lens.

How does pupillary dilation affect distance vision?

The ciliary muscle relaxes causing contraction of the Zonules of Zinn. This results in a flattening of the lens.

I explain why dilating your pupils is necessary during an eye examination in an answer to another question from a reader, so I will not repeat that information here. Click on this link to access the Pupil Dilation page.

Mydriatics, such as tropicamide and cyclopentolate typically relax the iris and ciliary muscles of the eye for about 4-6 hours. During this period of time, the lens of the eye remains flat. This means that your distance vision should have functioned reasonably well, as long as you were wearing sunglasses to protect your eyes from excess light entering through the pupil. However, relaxation of the ciliary muscle significantly compromised your ability to focus on things that were close.

Two things occurred to cause the discomfort that you experienced. First, you exercised your ciliary muscle beyond the point of fatigue. Think of how muscles in your body feel the day after engaging vigorous exercise, particularly if you have not done that activity for a while. Sometimes the ciliary muscle can spasm, which like any muscle spasm, can be quite painful.

Second, to compensate for the loss of ciliary muscle function, you likely did a lot of squinting. Squinting reduces peripheral vision in an attempt to restrict light entering the eye to that most closely associated with the item of focus. Muscles responsible for this action are the orbicularis oculi, which control blinking, and other facial muscles surrounding the eye. During the time in which you were using the computer, these muscles likely were exercised beyond fatigue as well. This further added to your discomfort.

You asked if the pain you were experiencing was normal. Although it was not a good decision to work on your computer following pupillary dilation, the discomfort was a normal reaction to straining the muscles inside and around your eyes. It will dissipate over time as the muscles recover.

To avoid this problem in the future, I recommend that you do not engage activities requiring close focus for 4-6 hours following an eye exam in which your pupils have been dilated. There are many activities that can be enjoyed that do not require close focus, including watching television (as long as you are seated at least 3 meters away from the screen).

Although distance vision largely is preserved during pupillary dilation, you still should not drive. The reason for this is twofold. First, even with sunglasses, your eyes still are unable to adjust to changes in light intensity. Sudden glare or reflected light could effectively blind you, something definitely not desirable when driving an automobile. Second, while for the most part intact, your distance vision still is not optimal. Because the ciliary muscle is relaxed, the ability to make fine adjustments to bring objects at different distances into focus is compromised. For this reason, it is advisable to arrange for transportation to return you home after an eye examination.

Carolina Valdivia, MD

REFERENCE:

Remington LA. Clinical Anatomy and Physiology of the Visual System, 3rd Ed. St. Louis, MO: Butterworth Heinemann Elsevier, 2012.

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