The dilation process is fairly simple: a doctor or technician instills eye drops that make your pupils expand.  The pupil is the ‘window’ that the doctor uses to examine the back (posterior) segment of your eye – the retina and the vitreous fluid.  In order to examine the posterior segment, your doctor will generally use an instrument (ophthalmoscope) that incorporates a light and a magnified viewing system.  Without dilating drops, the instrument’s light causes the pupil to shrink, virtually closing the viewing ‘window.’ 

The retina is the most important part of your eye – it processes the light that passes through the eye, and then transmits those images to the brain.  A dilated exam will better reveal ocular conditions such as macular degeneration, retinal detachments, retinal tears, swelling, hemorrhages, vitreous infections, tumors, glaucoma and cataracts.  A dilated exam can also reveal problems associated with ‘whole-body’ diseases like diabetes, vascular disease and hypertension.  Finally, with dilation a doctor can identify conditions still in their early stages and often without symptoms – helping us to minimize long-term vision loss.

Narrow angle glaucoma is the only common contra-indication for dilation, and repeated dilation does not harm the eye; absent this condition, you should opt for a dilated exam when given a choice.

The following animation is an overview of the dilation process.