How Cataracts Are Diagnosed

A cataract forms when proteins in the lens of your eye clump together, causing clouded or blurry vision along with a range of other symptoms.

Most people with cataracts will experience symptoms as the condition progresses, which can be brought to the attention of your eye doctor. Your doctor can then examine your eyes and test your vision to diagnose your condition.

It’s also possible that your doctor will spot a cataract in a routine exam before it causes any symptoms — or before you’ve noticed symptoms.

There’s no definitive test for cataracts. Instead, a diagnosis will be based on any vision loss or abnormalities detected in a series of tests.

Once your cataract is diagnosed, you’ll need to discuss with your doctor how to monitor it and decide when treatment might be necessary.

In most cases, there’s no need to take any immediate treatment steps when a cataract is first diagnosed. But your doctor may want to discuss how to slow your cataract’s progression or adapt your activities to minimize the impact it has on your life.

Depending on how severe or extensive your cataracts are, your doctor may recommend different intervals of follow-up appointments or monitoring. (1,2)

What to Expect at Your Eye Appointment

When you see an eye doctor about possible cataracts, the first thing your doctor will most likely do is ask you about your symptoms.

Questions about your visual symptoms may include:

  • How long you’ve noticed your symptoms
  • Whether your symptoms come and go
  • Whether your symptoms have gotten worse
  • Whether your symptoms interfere with daily tasks (3)

Your doctor may ask about specific visual symptoms, such as:

  • Cloudy or blurred vision
  • Distorted vision
  • Worsened night vision
  • Difficulty reading
  • Double vision
  • Glare or a halo effect from bright lights
  • Greater nearsightedness
  • Faded color vision (4)

Your doctor may also ask you questions about your personal and family medical history, such as:

  • Whether you have diabetes
  • Whether you’ve taken corticosteroids (oral or inhaled)
  • Whether any family members have had cataracts
  • Whether you’ve been diagnosed with another eye condition, such as glaucoma
  • Whether you’ve experienced any eye injuries
  • Whether you’ve undergone radiation as a medical treatment (2,4)

Based on your answers, your doctor will decide what tests are indicated to look for cataracts and evaluate how much vision loss they’ve caused.

Diagnostic Tests for Cataracts

After reviewing your medical history and symptoms, your doctor may perform one or more tests to evaluate your vision and get a closer look at your eyes.

Tests used to diagnose cataracts include:

Visual Acuity Test For this test, you’ll look at an eye chart showing rows of capital letters (usually) that are large at the top of the chart and progressively smaller toward the bottom of the chart. Your doctor will ask you to read from various areas of the chart.

Your eyes will be tested one at a time, with the other eye covered. Your doctor will determine whether your vision is normal, or 20-20, or whether your vision is impaired. (5)

For the purpose of diagnosing cataracts, it’s also important to note whether your vision has significantly worsened since your last exam.

Dilated Eye Exam Also known as a retinal exam, this test involves putting drops in your eyes that make your pupils dilate (widen).

Dilating your pupils makes it easier to look at the back of your eyes, known as your retina. Your doctor will do this using a specialized magnifying device, known as an ophthalmoscope.

This test lets your doctor look through your lens, spotting any abnormalities, as well as look at your retina and optic nerve, which connects your retina to your brain.

After this test, your vision may remain blurred from the eye drops for several hours. (6)

Slit-Lamp Test This test involves using a specialized microscope to look at the structures in the front of your eye.

This microscope, known as a slit lamp, uses a narrow line of light to examine your cornea (outer eye layer), iris (colored part of your eye), the space between your cornea and iris, and your lens.

The thin, strong line of light lets your doctor view small sections of these structures at a time, making it easier to spot any troublesome abnormalities. (2,3)

Tonometry This test measures the pressure inside your eye. It’s often used to help diagnose glaucoma, but may also be useful for cataracts.

Before the test, your doctor may give you eye drops to numb your eyes.

In a common version of the test, you’ll rest your head on a chin rest and line your eyes up with a device that delivers a puff of air to each eye. The machine will measure your eye pressure based on how light reflects off your eye when the puff takes place.

In the most accurate version of tonometry, the front of your eye will be stained with an orange dye, and you’ll rest your head on a support. A slit lamp will shine a narrow line of light onto your eyes.

Your doctor will place a measuring device (called a tonometer) so that it just touches the front of your eyes. Blue light will shine through the slit lamp, and your doctor will adjust a dial to read your eye pressure.

In another variation of the test, your doctor will use a small handheld device that resembles a pencil to instantly measure your eye pressure while touching it to your eye.

Because your eyes will have been numbed, each method of tonometry is painless and may cause only brief and minor discomfort. (2,7,8)

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