An eye exam helps detect eye problems at their earliest stage — when they’re most treatable. Regular eye exams give your eye care professional a chance to help you correct or adapt to vision changes and provide you with tips on caring for your eyes.

Several factors may determine how frequently you need an eye exam, including your age, health and risk of developing eye problems. General guidelines are as follows:

Children 5 years and younger. For children under 3, your pediatrician will likely look for the most common eye problems — lazy eye, crossed eyes or turned-out eyes. Depending on your child’s willingness to cooperate, he or she could undergo a more-comprehensive eye exam between the ages of 3 and 5.

School-age children and adolescents. Have your child’s vision checked before he or she enters first grade. If your child has no symptoms of vision problems and no family history of vision problems, have his or her vision rechecked every one to two years. Otherwise, schedule eye exams based on the advice of your eye doctor.

Three kinds of eye specialists may perform an eye exam:

• Ophthalmologists. Ophthalmologists are medical doctors who provide full eye care, such as giving you a complete eye exam, prescribing corrective lenses, diagnosing and treating complex eye diseases, and performing eye surgery.
• Optometrists. Optometrists provide many of the same services as ophthalmologists, such as evaluating your vision, prescribing corrective lenses, diagnosing common eye disorders and treating selected eye diseases with drugs. If you have a complex eye problem or need surgery, your doctor can refer you to an ophthalmologist.
• Opticians. Opticians fill prescriptions for eyeglasses, including assembling, fitting and selling them. Some opticians also sell contact lenses.

If you wear contact lenses or glasses, bring them to your appointment. Your eye doctor will want to make sure your prescription is the best one for you. Also be prepared to remove your contacts or glasses during the exam. Tests that use dye (fluorescein) to temporarily color your eyes may permanently discolor your contact lenses, so you’ll be asked to remove them for those tests.

If your eyes are dilated as a part of your eye exam, you may want to bring sunglasses to wear after your eye exam is complete, as daylight or other bright lights may be uncomfortable or cause blurred vision. Also, consider having someone else drive you home.

An eye exam usually involves these steps:

• You’ll be asked about your medical history and any vision problems you might be experiencing.
• Your eye doctor measures your visual acuity to see if you need glasses or contact lenses to improve your vision.
• You’ll be given numbing drops in your eyes. Then your doctor measures your eye pressure.
• Your eye doctor checks the health of your eyes, possibly using several lights to evaluate the front of the eye and inside of each eye. To make it easier for your doctor to examine the inside of your eye, he or she will likely dilate your eyes with eyedrops.
• Your eye doctor discusses what he or she found during the exam and answers questions you have about your eyes.

Part of the examination, such as taking your medical history and the initial eye test, may be performed by a clinical assistant.

Several different tests may be performed during the eye exam. The tests are designed to check your vision and to examine the appearance and function of all parts of your eyes.

At the end of your eye exam, you and your doctor will discuss the results of all testing, including an assessment of your vision, your risk of eye disease and preventive measures you can take to protect your eyesight.

Normal results from an eye exam include:

• 20/20 vision
• Good peripheral vision
• Ability to distinguish various colors
• Normal-appearing structures of the external eye
• Absence of cataract, glaucoma or retinal disorders, such as macular degeneration

Your doctor may give you a prescription for corrective lenses. If your eye exam yields other abnormal results, your doctor will discuss with you next steps for further testing or for treating an underlying condition.