A cataract is a spot in your eye where the clear lens, the part that focuses light, becomes cloudy, making your vision blurry or dim. Cataracts develop slowly. An optometrist or ophthalmologist, doctors specializing in diagnosing and treating eye conditions, diagnoses cataracts. They may also rule out other eye conditions, like glaucoma, that can have similar symptoms.
You can expect your healthcare provider to ask about your symptoms. Be sure to mention if you’ve noticed any symptoms of cataracts, such as:
- Blurry, faded, or dim vision
- More sensitivity to light
- Trouble seeing at night
Your healthcare provider will also likely ask about your medical history to help understand your risk for cataracts. They’ll look at factors that increase cataract risk, like:
- Age
- Past eye injuries
- Time spent in the sun, especially without sunglasses
- Smoking habits
- Health conditions like diabetes
- Family history of cataracts
- Use of medications such as steroids
A visual acuity test checks how clearly you can see at different distances. It uses a chart with rows of letters that get smaller as they go down. Your healthcare provider may ask you to read aloud from the chart while sitting or standing a certain distance away.
Eye doctors test each eye separately, sometimes with and without corrective lenses (glasses). This helps them see if any vision problems can be fixed with glasses or if cataracts are causing the symptoms.
A visual acuity test alone doesn’t confirm cataracts, but it gives your eye doctor a helpful starting point. Cataracts usually cause vision to worsen gradually rather than suddenly. Regular visual acuity tests help keep track of any changes in your vision over time, so it’s important to keep up with your regular eye exams.
A slit lamp is a special microscope with a bright light that helps your healthcare provider examine areas of your eye, like the cornea, iris, lens, and retina, under high magnification for any problems.
During this exam, your healthcare provider may put eye drops in your eyes to make your pupils widen (dilate). This helps them see the structures of your eye more clearly.
This test helps find early signs of cataracts and other eye conditions that could affect your vision. By changing the light’s brightness and angle, your healthcare provider can see the size, shape, and location of any cloudiness in the lens.
A retinal eye exam also involves putting dilating drops in your eyes to widen your pupils. This helps your eye doctor get a better view of the structures inside your eye, including the lens, retina, and optic nerve.
Once your pupils are dilated, the eye doctor uses an ophthalmoscope, a tool with a bright light and magnifying lens, to look at your eye lens. While dilation can blur your vision and make you more sensitive to light, it helps the doctor assess the severity of cataracts, if you have them, and overall eye health.
A retinal exam is useful for detecting cataracts that form at the back of the lens and can cause problems like glare sensitivity and trouble reading. These are called posterior subcapsular cataracts.
Tonometry measures the pressure inside your eyes (intraocular pressure). This helps detect glaucoma, another eye condition that interferes with vision. Cataracts may sometimes cause eye changes that indirectly increase the risk of glaucoma.
There are different types of tonometry tests. Your eye doctor may use one of the following:
- Noncontact tonometry (air puff): For this test, you sit in front of a machine and place your chin on a support to keep your head steady. The machine releases a quick puff of air that slightly flattens your cornea, the clear part in front of your pupil and iris. A light beam measures how much your cornea moves to calculate eye pressure. While the air puff might be somewhat startling, the test is painless.
- Goldmann applanation tonometry: The most accurate method for measuring eye pressure, this test quickly and painlessly measures the force needed to flatten the cornea. Before the test, your eye doctor will put numbing drops in your eyes. Then, they will bring the tip of a tool (tonometer) close to your eye. As the tool touches your eye, your eye doctor adjusts a dial to measure the pressure in your eye.
- Handheld tonometry: Some eye doctors use a pen-like tool that briefly touches the cornea and instantly records eye pressure. Like the Goldmann applanation method, this test also involves placing numbing drops in your eyes before the test.
While cataracts are a common cause of vision changes, other eye problems can cause similar symptoms. Eye doctors may do extra tests to check for other conditions that affect vision and eye health. These include:
- Macular degeneration: Age-related macular degeneration (AMD) also causes blurry or distorted vision, but it mainly affects your central vision, not the overall sharpness of your vision. A test called optical coherence tomography can help doctors diagnose AMD.
- Glaucoma: You can have both glaucoma and cataracts, so eye doctors use tonometry to check for glaucoma-related vision loss. Glaucoma usually causes a gradual loss of peripheral (side) vision.
- Diabetic retinopathy: People with diabetes can develop diabetic retinopathy, which damages blood vessels in the retina and causes symptoms like blurry vision and floating spots in your vision. A dilated eye exam can help eye doctors diagnose or rule out diabetic retinopathy.
To know if you have cataracts, eye care professionals called optometrists and ophthalmologists will likely review your medical history and symptoms to see if you’re at risk. Then they may use several tests to help make a diagnosis. These tests include a visual acuity test, slit-lamp exam, dilated eye exam, and tonometry.
Because other eye conditions can cause similar symptoms to cataracts, your healthcare provider may do extra tests to rule out these conditions.
