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At just about every eye exam, the optometrist or ophthalmologist administers some sort of yellow gel-like fluid directly onto your eyes with a pipette. The solution feels somewhat unctuous and uncomfortable, and it might distort your close-range vision for an hour or two, but other than that, you might not know much about it. Your doctor might tell you that the substance helps to dilate your pupils, but he may not have elaborated further. For all of you who may be curious as to why your pupils require dilation during an eye exam, read on!


The retina is the only place in the human body where blood vessels and neural tissue can be directly observed without any sort of surgery. Once the pupil is fully dilated (which takes approximately thirty minutes after application of the eyedrops) the optometrist can see all the way to the back of the eye. By looking through the pupil, an optometrist can easily examine the retina with a flashlight. Normally, direct light would cause the pupil to shrink to the size of a pencil point, making a very small aperture for the optometrist to view the retina. By dilating the pupils and effectively paralyzing the muscles that respond to light by expanding and contracting the pupil, the optometrist is able to view the entire retina through a larger window. Furthermore, disabling the eye’s natural response to change focus and light intake is what causes patients to have trouble reading or experience light sensitivity for a few hours after an eye appointment.

Examining the retina is very important, since several diseases and conditions can be detected in their earliest stages simply by observing the retinal tissue. Some of these conditions include diabetes, eye tumors, macular degeneration, glaucoma, and high blood pressure.


The short answer is no. Not every exam requires a pupil dilation, but checking the inside of your eyes is usually a good idea during an eye appointment. Before determining whether dilation is necessary for you, your optometrist will consider the following criteria:

  • Your age: As you age, your risk of contracting certain diseases or conditions increases. The National Institutes of Health recommends scheduling an annual eye dilation and exam.
  • Your current eye health: Obviously, certain preexisting conditions may require you to keep a close eye on the health of your retinas. Having a history of eye diseases related to the back of your eye may put you at a higher risk of developing eye problems in the future.
  • Your overall health: Multiple seemingly unrelated factors can contribute to eye problems, such as your diet, or how much you exercise. In addition, diseases like diabetes or high blood pressure can negatively affect your eyes.
  • The purpose of your eye examination: Certain injuries and conditions might not require a dilation to determine the cause or solution of the problem. Follow-up examinations for previously addressed conditions might not require a pupil dilation either, unless new developments arise.

Has it been awhile since your last dilation? Is it time for an eye exam? Contact Silverstein Eye Centers today at (816) 358-3600 or request your appointment online. We can serve you at our convenient location in Independence/Kansas City.

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