What Is the Difference Between an Optometrist and an Ophthalmologist?

Optometrists and ophthalmologists are both eye doctors, but they have different levels of training and areas of expertise. If you have a problem with your vision or overall eye health, it's important to make sure that you consult the right doctor for the job.

Optometrists

Optometrists examine, diagnose, treat, and manage diseases and disorders of the eye. Unlike ophthalmologists, an optometrist doesn't have a medical degree (M.D.), but rather a doctor of optometry (D.O.). To earn this qualification, optometrists first obtain a pre-professional undergraduate degree, followed by four years of professional education at a college of optometry, with an optional residency in order to specialize in a particular area.

Conditions Optometrists Treat

Though optometrists are probably best known for completing routine vision tests to help patients address any vision problems and get a prescription for eyeglasses or contacts, they do much more than that.

While optometrists certainly have the ability to perform routine vision tests, they typically provide a comprehensive eye exam, which involves more than having you read random letters on a poster across the room. These exams are also crucial for assessing the health of a patient's eyes and eye tissue, as well as screening for a variety of conditions, like glaucoma.

Additionally, the screenings optometrists perform during a comprehensive exam may help identify previously undiagnosed conditions like diabetes, high blood pressure, autoimmune diseases, and cancers. Or, if an optometrist knows that a patient has diabetes, for example, they can keep a closer eye out for how the condition might impact the person's eye health.

Optometrists can also assess a person's eye injury—though in more serious cases, they may refer the patient to an ophthalmologist for the treatment required.

Treatments Offered by Optometrists

While all optometrists are able to prescribe eyeglasses, contact lenses, and other visual aids, beyond that, much of the scope of their practice is determined by state law. For example, some states allow optometrists to write prescriptions for medications, while others don't. Similarly, optometrists perform some minor surgical procedures to correct or treat visual or eye health issues, which are also determined by state law.

Optometrists also provide nonsurgical treatments, like vision therapy and low-vision rehabilitation. Another part of the job is offering pre- and postoperative care to patients undergoing eye surgery, like giving them an eye exam the day after their procedure to make sure everything looks the way it should.

If a patient has more serious eye conditions or requires surgery or more intervention, an optometrist will refer them to an ophthalmologist for further assessment and/or treatment.

Equipment Used by Optometrists

Given the wide range of tasks optometrists perform and treatments they offer, they require several different types of equipment. Much of it is also used by ophthalmologists, who are qualified to provide any of the examinations and treatments an optometrist can, in addition to others (which we'll discuss below). Optometrists' equipment includes:

• Exam chair
• Retinal camera
• Phoropter (an instrument used to measure refractive error and determine eyeglass prescriptions)
• Binocular indirect ophthalmoscope (an instrument used to examine the interior structures of the eye, worn on the optometrist's head)
• Manual keratometer (used to determine how flat or steep the cornea is)
• Autorefractor (the machine used to measure a person's refractive error and determine their prescription for eyeglasses or contact lenses)
• Slit lamp (a microscope with a light attached used to examine the cornea, iris, and lens)
• Tonometer (used to measure the pressure of the eye)
• Lenosmeter (used to measure the power of an existing lens)
• Retinoscope (used to shine light into a patient's eye so the doctor can observe the reflection off the retina)
• Direct ophthalmoscope (used to examine the interior structures of the eye)

Ophthalmologists

Ophthalmologists are medical doctors (M.D) who diagnose and treat all eye diseases, perform eye surgery, and prescribe eyeglasses and contact lenses.

In order to become an ophthalmologist—and licensed to practice medicine and surgery—a person must complete a four-year undergraduate degree, four-year medical school degree, followed by a mandatory one-year internship, and three-year clinical surgery residency with an additional one to two years or more of fellowship.

Conditions Ophthalmologists Treat

Ophthalmologists are trained and qualified to treat any condition or injury involving the eye, including:

• Cataracts
• Glaucoma
• Farsightedness
• Nearsightedness
• Astigmatism
• Strabismus (crossed eyes)
• Optic nerve disease
• Systemic neurological diseases with visual manifestations
• Retinal detachments
• Diabetic retinopathy
• Systemic or inflammatory diseases involving the retina and vitreous
• Pediatric eye conditions

Treatments and Equipment

In addition to being able to write prescriptions for eyeglasses and contact lenses, ophthalmologists also have the authority to prescribe any relevant medications to patients. And while cataract surgery and basic glaucoma surgery are the two most common procedures ophthalmologists perform, they also perform surgery required for all the conditions listed above.

Similarly, ophthalmologists use the same pieces of equipment as optometrists (described above), with the addition to any surgical instruments or tools required for eye surgery.

Subspecialties for Ophthalmologists

Some ophthalmologists opt to complete an additional year or two of training in order to specialize in one particular aspect of eye health. These subspecialties include:

• Glaucoma: Uses medicine, laser, and surgery to manage eye pressure.
• Retina: Diagnoses and manages retinal diseases, including macular degeneration and diabetic eye disease; surgically repairs torn and detached retinas and treats problems with the vitreous.
• Cornea: Diagnoses and manages corneal eye disease, including Fuchs’ dystrophy and keratoconus; performs refractive surgery (such as LASIK) and corneal transplants; treats corneal trauma; handles complicated contact lens fittings.
• Pediatrics: Diagnoses and treats misalignment of the eyes, uncorrected refractive errors and vision differences between the two eyes, and other childhood eye diseases and conditions.
• Neurology: Diagnoses and treats vision problems related to how the eyes interact with the brain, nerves, and muscles. 
• Oculo-Plastic Surgery: repairs damage to or problems with the eyelids, bones, and other structures around the eyeball, and in the tear drainage system.

Choosing the Right Eye Doctor

After reading about what optometrists and ophthalmologists do, you may be unsure of which practitioner to see for your needs. If you are having difficulties with your vision—and think you may need glasses or contact lenses—an optometrist is a good choice. Make sure to get a comprehensive eye exam while you're there. If anything comes up that is a concern to the optometrist, they will refer you to an ophthalmologist for further assessment and/or treatment.

If you are dealing with an eye issue that requires surgery, have an eye condition, or have another health issue that also impacts the eyes, it's a good idea to see an ophthalmologist. Also, if you have not had a comprehensive dilated eye exam by the time you're 40 years of age, then it is time to schedule an appointment with an ophthalmologist, as part of your routine health maintenance screenings—even if you don't think you have any problems with your eyes or vision.

When seeing either an optometrist or ophthalmologist, you can expect the standard type of customer service as you'd receive with any other medical doctor or practitioner. And like any type of healthcare, the costs of seeing an optometrist and ophthalmologist depend on factors like your health insurance, and what a particular practice or medical facility charges.

Both types of eye doctors will let you know if you need to return for follow-up appointments or require any treatments.

A Word From Verywell

There is so much more to eye health than getting a vision test and a prescription for eyeglasses or contact lenses if needed. Of course, that part is really important because many people need aids in order to have functional vision. But when it comes to more serious issues involving eye health—or anything requiring surgery—an ophthalmologist is your best bet.