Sense of Contrast

Introduction

Contrast is a color or brightness that distinguishes an object or its representation in an image or display. Humans have sense organs like the nose, ear, and eyes that allow us to take in information from our surroundings. Each sense organ is a part of a sensory system that accepts sensory inputs and sends sensory data to the brain.The visual system is responsible for detecting and processing light reflected from non-emissive objects around the environment, including the moon, trees, animals, rocks, and televisions and computer displays. When the eye directs light to the retina, visual perception occurs. There is a layer of photoreceptor (light-receiving) cells in the retina that are made to convert light into a sequence of electrochemical signals that can be sent to the brain. Electrochemical signals from the optic nerve and thalamus travel through these structures on their way to the brain's cerebral cortex, where the visual experience takes place. According to a 2017 study, the process can occur in 13 milliseconds. The difference between an object and other things in the same field of vision in terms of color and brightness determines the contrast in the real world.

What Is the Sense of Contrast?

Sense of contrast or visual contrast sensitivity is the visual process of recognizing the differences in color or brightness (luminance) between two things or between an object and its surroundings. It is an essential component of how the eyes work, especially in low-light environments. A strong contrast between an object and its surroundings requires visual perception. The ideal ratio should be 2:1. It is harder to differentiate between two shapes when the contrast is low. The quality of vision is affected by contrast sensitivity, considered as significant as visual acuity.

How Does the Sense of Contrast Sensitivity Affect Vision?

The capacity to distinguish between two identical colors or shades of gray is known as contrast sensitivity. It aids in the ability to distinguish an object from its surroundings. The quality of vision is affected by contrast sensitivity, considered significant as visual acuity. This differs from the standard visual acuity testing performed during a regular eye exam, which assesses the capacity to read letters that are getting smaller and smaller on an eye chart. Contrast sensitivity is a significant marker of visual function, particularly during low-light, foggy, or glare conditions where the contrast between objects and their background frequently is reduced. Driving at night, in the rain or fog, or reading a newspaper with words written on a gray background are a few everyday situations that require contract sensitivity.

What Are the Signs and Symptoms of Reduced Visual Contrast Sensitivity?

The signs and symptoms of reduced contrast sensitivity include:

• Difficulty reading.

• Difficulty in recognizing faces.

• Unable to detect a proper color.

• Cataracts.

• Glaucoma.

• Diabetic retinopathy.

• Refractive eye surgery like laser surgery or photorefractive keratectomy.

• Eye injury or trauma.

• Macular degeneration.

What Are the Diagnostic Tests Available for Reduced Visual Contrast Sensitivity?

The diagnostic tests available for reduced contrast sensitivity includes the following:

• Pelli- Robson Chart - In this chart, the letters are all the same size but are progressively less bright. The patient may be able to read the chart from one meter away. It is quick and looks like standard vision charts. It helps find cataracts and monitor drivers for visual problems.

• Vision Contrast Test System - In this test, bright and dark circles are arranged in rows and columns. The contrast is reduced from left to right.

• Bailey-Lovie Test - This examination evaluates contrast sensitivity and visual acuity.

• Functional Acuity Contrast Test - In this test, the patient is tested three times after showing the test rows in a random order.The lowest contrast patch must receive at least two out of three right answers in order to receive a final contrast sensitivity score.

Other tests includes:

• Cambridge test.

• Mars contrast sensitivity test.

• Test chart 2000.

How Can Visual Contrast Sensitivity Be Improved?

The quality of vision is affected by reduced contrast sensitivity. To determine the cause of any vision loss, the eye doctor will first assess the contrast sensitivity.

• Treatment of Underlying Conditions - Some conditions, such as glaucoma, cataracts, age-related macular degeneration, myopia, and optic neuritis, may reduce contrast sensitivity.

• Wearing Contact Lenses - The eye doctor may advise wearing contact lenses with a yellow filter for low contrast sensitivity to increase the capacity for contrast.

• Prescription Eyeglasses - The eye doctor may advise that wearing prescription eyeglasses with anti-reflective coating improves night vision.

• Artificial Tears - Doctors may also advise the patient with dry eyes. Severe dry eye reduces contrast sensitivity. In these situations, artificial tears used to lubricate the eye can restore contrast sensitivity.

What Precautions Have to be Taken to Maintain a Healthy Vision?

• Regular Eye Exams - Regular eye examinations may help the doctor detect and treat any issues with the eyes. It is important to schedule annual eye exams so any abnormalities can be treated as soon as they arise.

• Wearing Sunglasses - Sunglasses are more than simply a statement of fashion; they also protect the eyes from harmful sun rays and help delay the aging of the eyes.

• Wearing Eye Protections - Eye protection should always be worn when working or participating in activities where an eye injury may occur. Various sports, construction projects, and factory tasks may fall under this category.

• A Nutritious Diet - Select eye-healthy foods like salmon, fruits, and vegetables. Eating leafy greens like spinach, kale, and collards is very healthy for the eyes.

• Regular Exercise - Finding the time to exercise regularly may help avoid several health problems throughout life. Diabetes and high blood pressure are two conditions that can affect eyesight.

• Avoid Smoking - Quitting smoking can lower the risk of developing conditions, including cataracts and macular degeneration.

Conclusion

A sense of contrast helps with distinguishing an object from its surroundings. Loss of contrast sensitivity is a common and distressing condition. It makes it challenging to read, handle accounts, and drive, frequently resulting in accidents, falls, and a poor quality of life. Routine appointments with the ophthalmologist may prevent further reduction in vision. Meanwhile, a quick and inexpensive method that can be done at home is to use color and contrast to promote visibility and safety.