Tackling Glare: How Anti-Reflective Coating and Anti-Glare Coating Improve Your Eyewear Experience

 بسم اللّٰہ الرحمٰن الرحیم 

In today's world, our eyes are constantly exposed to various sources of glare and reflection. We spend great deal of time on digital devices like computer, mobile phone, laptop etc as well as outdoor activities specially driving expose our eyes to bright light sources. This can lead to visual discomfort, reduce visibility and even potentially harm eye health.

An appropriate lense coating for your eyewear, can solve this problem easily . You'll commonly notice terms like anti reflective coating and anti glare coating while selecting lenses for your glasses. Despite that these terms might sound similar, each has unique benefits depending on the condition of light in surroundings.

In this article we’ll explore what is glare, its causes and impact on eyes, and how anti reflective and anti glare coatings work to tackle glare in different conditions to improve our visual experience.

What is Glare?

When excessive amount of light enters eye, it impairs vision and makes it difficult to see causing visual discomfort. This is called glare.

It can happen from external light sources as well as from reflections within the eye.

Causes of Glare from External Sources

1. Sunlight:

Sunlight is one of the primary outside sources of glare. Visibility is reduced by sunlight shining directly into one's eyes. Water, sand, snow and glass also reflect sunlight causing glare.

2.Headlights:

 Strong headlights from oncoming cars create glare that causes visual discomfort. This happens mostly at night or in low light conditions.

2. Artificial Lighting:

 Overhead lights, streetlights, or even screen glare from computers and smartphones can be sources of glare.

Causes of Glare within the Eye

1.Cataracts:

Clouding of the eye’s natural lens scatters light, leading to glare.

2.Refractive Errors: 

 Light rays don't get focused on specific point in conditions like myopia, hypermetropia and astigmatism. These scattered light beams can cause glare, especially in high refractive errors.

3. Dry Eyes:

Insufficient tear production scatters light more, leading to glare.

4. Corneal Scarring:

Surface irregularities from scars on the cornea can scatter light and produce glare.

5. Age Related Changes:

Eye lenses can become less transparent with age, spreading light more widely and creating more glare.

6. Eye Surgeries:

The structure of optical surface is affected by procedures like cataract removal and refractive treatments such as PRK, LASIK and LASEK. It scatters light, leading to post operative glare. 

Anti Reflective Coating and Anti Glare Coating

What is Anti Reflective Coating on Eyeglasses?

The layer with varying refractive indices is applied to lens surface to minimize reflections, is known as anti-reflective or AR coating. This means less light is reflected off the lens, allowing more light to pass through. The result is reduced glare and less eye strain.

 How Anti-Reflective Coating Works? 

Here is how anti reflective coatings work: 

Layered Structure:

• AR coatings consist of multiple thin layers with alternating high and low refractive index materials.

• This variation causes incoming light to refract (bend) as it passes through each layer. 

Light Interference

• By strategically adjusting the refractive index of each layer, AR coatings create a gradual transition for light as it passes from air through the coating and into the lens material. 
• As a result, there is less light reflected back to the viewer's eye. This reduces reflections by producing destructive interference, in which light waves cancel each other out. 

Advantages of Anti Reflective Coating

Enhanced Visual Clarity:

 Anti-reflective coatings increase contrast and visual clarity by minimizing reflections, particularly in low light.

Reduced Eye Strain:

When working on digital devices like computers, laptops, and smartphones, or when working in dimly lit environments at night with AR coated glasses, then less glare means that there is no need to squeeze eyes to see clearly. Hence eye strain is reduced that facilitates prolonged concentration. 

 

Improved Vision in Different Eye Conditions: 

In different eye conditions, such as cataract, dry eyes, corneal scarring, refractive errors, age-related changes, post- refractive surgery effects or any opacity in optical media, light scatters within the eye producing glare. As mentioned earlier that AR coatings reduces reflections from both surfaces of lens due to gradually changing refractive index, so glare due to these eye conditions is reduced, improving visual clarity. 

Disadvantages of Anti-Reflective Coating 

Maintenance: 

AR coated lenses can smudge easily and require frequent cleaning. 

Cost: 

These coatings can add to the overall cost of eyewear. 

Durability: 

Some AR coatings may scratch easily, though advancements have improved this aspect. 

Types of Anti Reflective Coatings and Their Benefits 

Blue Anti Reflective Coating:

1.Blue Light Protection:

Blue AR coating filters the blue light emitted by digital screens. As wavelength of blue rays is particularly harmful for eyes when you are using computer, smartphone or tablet for extended period of time.

2. Better Contrast and Clarity:

Enhances contrast and clarity when looking at digital screens, making text and images appear sharper.

Green Anti Reflective Coating:

1. Natural Light Transmission:

Offers a more natural light transmission, reducing reflections and improving clarity without significantly altering the color perception.

2. Versatile Use:

It is effective in both indoor and outdoor lighting conditions. So it is more appropriate for everyday usage.

3. UV and Harmful Ray Protection:

Hazardous UV radiation and other high energy visible (HEV) light are also blocked by green AR coatings. The risk of eye damage from extended exposure to the sun and other dangerous rays is reduced, hence promoting overall health of eyes. 

What is Anti Glare Coating on Eyeglasses?

The layer with polarizing filters that reduce the intensity of light reaching eyes is known as anti-glare coating. This minimizes glare from external light sources, such as sunlight and headlights.

How Anti-Glare Coating Works?

It works as following: 

Coating Structure:

• Anti-glare coatings typically incorporate anti reflective (AR) properties along with polarizing filters or other light-filtering technologies. 

Polarization:

• Polarizing filters block specific orientations of light waves. Smooth surfaces like water or roads polarize light horizontally that creates glare.
• The polarizing filter in the anti-glare coating blocks these horizontal light waves, reducing the intensity of the glare that reaches your eyes.

 

 Advantages of Anti-Glare Coating 

Improved Vision:

These coatings improve visual clarity by minimizing glare, especially in bright outdoor environments and during nighttime driving. 

Comfort: 

Decreased glare leads to decreased eye strain, so it's easier to see clearly without squinting eyes. Hence there is no more visual discomfort. 

Safety: 

Enhanced visibility reduces the risk of accidents caused by glare, especially during activities like driving or sports. 

Disadvantages of Anti-Glare Coating

Potential Clarity Reduction: 

Some anti-glare coatings may slightly reduce sharpness or resolution due to light diffusion. 

Limited Functionality:  

They are effective against external light sources but may not significantly reduce internal reflections within the eye like AR coatings. 

Cost: 

 Though anti-glare coatings cheaper than AR coating but they increase the overall cost of eyewear.

Which One is Better for You?

• For using digital devices for longer period of time especially in low light conditions you should go for anti-reflective coating.

• People suffering from glare due to aforementioned eye conditions should also choose anti reflective coating for their glasses.

• If you frequently encounter bright external light sources, such as sunlight while driving or being outdoors, anti-glare coating will be beneficial.

• For the best results, choose eyewear lenses that combines benefits of both coatings.

• Nonprescription glasses such as sunglasses, reading glasses or computer glasses are also provided with anti reflective and anti glare coatings.

• Night drivers can also use nonprescription transparent plano lens with these coatings to avoid glare from headlights.

 These coatings can be a useful addition to your eyewear if you drive frequently at night, spend a lot of time on digital devices, or just want better eyesight. Choosing the right coating for your specific need and lifestyle can greatly improve your visual comfort and overall level of eye health.