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Can Glaucoma Affect Contrast Sensitivity?

Contrast sensitivity is the eyes’ ability to identify an object not clearly defined from its background.

Glaucoma is among the many factors that can cause changes in contrast sensitivity. Other conditions affecting contrast sensitivity include cataracts, age-related macular degeneration, myopia, optic neuritis, and retinal disorders.

When glaucoma affects your vision, it makes it harder for your brain to detect differences in luminance. In other words, glaucoma makes the contrast between an object and its background more challenging to detect.

What Is Contrast Sensitivity?

Contrast sensitivity is the eyes’ ability to identify an object not clearly defined from its background. Contrast refers to the difference in the luminance or color that makes it possible to distinguish an object. It enables us to see well in different conditions, like foggy or rainy days and allows us to identify road signs when driving during the night. Contrast sensitivity is vital to your visual function, especially in low-light situations.

Everyday situations that rely on contrast sensitivity include:

  • Driving at night and in rainy or foggy conditions
  • Reading materials with poor contrast, like a newspaper
  • Navigating steps or curbs
  • Locating an object against a similarly colored backgroun
  • Distinguishing facial features on others

How Is Contrast Sensitivity Measured?

Contrast sensitivity isn’t measured in a routine eye exam but rather by using a Pelli-Robson contrast sensitivity chart, a Mars Letter contrast sensitivity test, or sine-wave grating targets.

  • The Pelli-Robson chart features horizontal lines of uppercase letters in a uniform size. You start from the top of the chart and read each row until you can no longer see any letters against the white background.
  • The Mars-Letter contrast sensitivity test features a similar chart, but the chart is smaller and viewed at a closer distance.
  • Sine-wave gratings resemble fuzzy lines of alternating light and dark shades of gray. The thickness of the lines varies as you view them on a computer screen or a wall chart. It signals to your doctor how well you can see under low, medium, and high-contrast situations.

How Does Contrast Sensitivity Differ From Visual Acuity?

Contrast sensitivity is sometimes confused with visual acuity, but they measure two different eye capabilities. Visual acuity refers to how sharp your vision is from a distance. Unlike contrast sensitivity, your visual acuity is tested during a routine eye exam.

How Is Visual Acuity Tested?

There are a few different ways to test visual acuity, including:

The Snellen eye chart
The Snellen eye chart is perhaps the most well-known visual acuity test, with its familiar rows of letters in decreasing sizes. For the test, you’re placed 20 feet from the chart and instructed to read each row until you can no longer read any rows.

The Random E test
The Random E test is also familiar to most people. It uses a capital letter E that gets smaller and changes direction (up, down, left, right). The test concludes when you can’t tell which direction the E is facing.

Simplified testing for children
When testing children, the doctor might test them using pictures or stories.

Symptoms of Reduced Contrast Sensitivity

People with reduced contrast sensitivity may experience:

  • Poor vision while driving at night and in rainy or foggy weather
  • Difficulty gauging curbs and steps
  • Eye strain from watching TV or reading
  • Images that appear washed out
  • Problems reading materials, like newspapers, where the print contrast against the paper background is poor
  • Distinguishing objects that are similar in color to their background, like finding a black wallet in a black purse; determining when your coffee is near the top when pouring it into a black mug; or picking out black socks in a shadowy drawer
  • An inability to identify the food on your plate

If you experience any of the above symptoms, talk to your doctor and get tested for contrast sensitivity. The test is painless, requires no advanced preparation, and takes only a few minutes.

Schedule Regular Eye Exams

There is currently no cure for glaucoma. Therefore, it’s critical to be examined regularly by your doctor to detect glaucoma. The earlier glaucoma is detected, the more effectively your doctor can treat it. Glaucoma treatments can minimize or prevent vision loss and blindness in most cases.

Help Us Find a Cure

The diligent work of researchers continues to lead to a better understanding of glaucoma every day. As a result, there’s great hope for new and improved treatments, including superior drug delivery methods, laser treatments, and less invasive surgical techniques. You can help make that happen!

Every contribution helps bring us closer to finding a cure for glaucoma. Whether you donate cash or stock, create a fundraising event, or even donate a vehicle or boat, your donation will give hope to those living with glaucoma and accelerate our research.

 

Posted on October 4, 2022