Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Eye Health Center

Font Size

Cornea, Lens, and Iris


The iris is the colored part of the eye. A circular muscle in the iris controls the amount of light entering the eye through the pupil, the black area in the center of the iris.

The cornea is the outer clear, round structure that covers the iris and the pupil. The cornea directs light rays into the eye and helps focus them on the light-sensitive retina at the back of the eye, providing sharp, clear vision.

The lens is located behind the iris and is normally clear. Light passes through the pupil to the lens. Small muscles attached to the lens can make the lens change shape, allowing the eyes to focus on near or far objects.

ByHealthwise Staff
Primary Medical ReviewerAdam Husney, MD - Family Medicine
Specialist Medical ReviewerChristopher J. Rudnisky, MD, MPH, FRCSC - Ophthalmology

Current as ofSeptember 9, 2014

WebMD Medical Reference from Healthwise

Last Updated: September 09, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

Woman holding tissue to reddened eye
Learn about causes, symptoms, and treatments.
Simple annoyance or the sign of a problem?
red eyes
Symptoms, triggers, and treatments.
blue eye with contact lens
Tips for wearing and caring.
Understanding Stye
human eye
eye exam timing
vision test
is vision correction surgery for you
high tech contacts
eye drop