How Dilation Helps Your Ophthalmologist Examine Your Eyes Thoroughly

When you go to the eye doctor (ophthalmologist or optometrist) for an eye exam, the doctor doesn’t just test your corrective eyeglass prescription. Instead, the annual comprehensive exam includes examination of the interior and exterior eye structures. A comprehensive exam includes looking at these structures under magnification to determine if you’re developing any eye diseases or other problems. To accurately examine those structures, the doctor needs a close-up view of all its structures. The way to do that is to dilate your eyes to ensure that everything’s visible.

At Retina Specialists, our team of expert ophthalmologists is passionate about making sure your vision is sharp and your eyes stay healthy. That’s why they stress the importance of getting a comprehensive dilated exam, both for your annual visit and after any kind of injury.

Here’s why dilation is so important:

The parts of the eye

To understand how healthy, normal vision works and what can go wrong, it helps to know something about how the eye is put together. The easiest way to describe it is to follow the way light travels. 

Incoming light first hits the eye’s surface, which is covered with the corneal membrane that’s clear and curved. The clear area allows light through, while the curved area (cornea) protects the eye and focuses the light further into the eye.

The corneal-focused light then moves through:

• The anterior chamber, filled with fluid called the aqueous humor
• The pupil, an opening in the chamber
• The lens, which fine-tunes the focusing
• The vitreous, another fluid-filled chamber

Finally, it strikes the light-sensitive tissue lining the back of the eye (retina).

The retina converts the light waves into electrical signals and sends them to the brain through the optic nerve. Your brain decodes the image, at which point you’re able to “see” it.

The retina also contains a small, central region known as the macula; it makes up only 2% of the retinal tissue, but it’s what registers your clear, central vision.

Why do my eyes have to be dilated?

A refraction is a test that evaluates your visual acuity (how well you see), and your eyes don’t have to be dilated to produce accurate results. The doctor may prescribe glasses or contact lenses if you need correction. 

A comprehensive eye exam, though, not only evaluates acuity but also the health of your inner and outer eye. Dilation is a critical part of the exam, because it allows the doctor to closely inspect all parts of the inner eye and determine if there’s any structural problem or disease.

When exposed to light, your pupil becomes smaller to prevent overloading. That means if your doctor shines a light into your eye, he won’t be able to see a thing since the pupil is constricted. Instead, we use special eye drops that force the lid muscles open so we can see the eyeball in its entirety, all the way back to the retina, macula, and optic nerve.

During a dilated exam, we can detect problems like the development of an eye tumor, trauma, or malformed structures. 

We can also diagnose and monitor a number of eye diseases:

• Torn or detached retina: retinal tissue pulls away from the underlying connecting tissue, leading to vision loss
• Diabetic retinopathy: blood vessels leak into tissue or grow abnormally on the retina
• Detached vitreous humor: often age-related, causes eye floaters (spots in vision)
• Glaucoma: damage to the optic nerve
• Macular degeneration (AMD): protein build-up and unusual blood vessel growth destroy the macula and central vision
• Cataract: clouding of lens

Since most of these conditions don’t produce symptoms until they’re advanced, you may be unaware you need treatment unless you get your eyes dilated.

How will dilation affect my vision?

When we put in dilating drops in your eyes, expect them to remain at that level of dilation for about 4-6 hours,

Dilating drops don't usually affect your distance vision, but can make it difficult for your eyes to focus on things close up. That means reading, looking at your phone, sewing, and other near-vision tasks will be difficult for a bit. To avoid missing work, make your appointment for later in the day.

Dilating drops also increase your light sensitivity, so definitely bring sunglasses with you to reduce the glare when you go outside, and don’t look directly at any bright lights. Also avoid driving, both because of glare and because your vision will remain fuzzy for a bit.

If you haven’t had a dilated eye exam for a while, it’s time to come into Retina Specialists so we can make sure your eyes remain healthy and clear. Call any of our five Texas offices — in Dallas, DeSoto, Plano, Mesquite, and Waxahachie — to make an appointment, or book online.