Why Do Eye Doctors Dilate Your Eyes?

Your eye doctor may dilate your eyes for a retinal examination.

Your eye doctor may dilate your eyes to perform a retinal examination (also called ophthalmoscopy or fundoscopy). This exam involves looking at the back of your eyes, including the retinas, optic disks and blood vessels that nourish the retinas.

Background

Dilating drops make the pupils of the eyes bigger so that the doctor can see the back of the eye. Because the pupils are bigger, you are more sensitive to light until the effect wears off, and it's a good idea to have sunglasses for use after the exam.

Direct Examination

Your eye doctor can do the retinal examination in three ways. The first, direct examination, involves shining a beam of light through your pupil and using an ophthalmoscope to see the back of your eye. Sometimes eye doctors do not dilate the eyes for this examination.

Indirect examination

For an indirect examination, your eye doctor holds each eye open and examines it with a bright light mounted on her forehead.

Slit-Lamp Exam

For a slit-lamp exam your doctor uses a slit lamp (microscope with a light attached) and an accessory condensing lens or a contact lens to get a more-detailed view of the back of your eye than is available in direct or indirect examination.

Considerations

Dilation and thorough examination of the back of the eyes are especially important for people at risk for eye disease to completely assess the health inside the eyes, according to All About Vision.

References

• Eye Exam: What You Can Expect
• What to Expect From a Comprehensive Eye Exam