January 21, 2014 | POSTED BY | Clinical Optometry, Events.
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The Problem with Today’s Glasses…

When it comes to regular ophthalmic lenses, there are many factors that can negatively affect a person’s vision: glare, UV radiation, and smudges are some of the most common. In addition, poor driving conditions, indoor florescent lighting, computer screens, and cell phone screens can also increase the chances of experiencing poor vision.

For patients that require high clarity in all settings throughout their day, applying an anti-reflective treatment on their glasses will help to eliminate factors that can negatively affect their vision.

Nature of Light Through a Lens 

When light enters a lens, its tendency is to change the direction by reflection, refraction, absorption, or transmission. Most of the light entering an ophthalmic lens is either refracted or transmitted, but a small amount of the light is absorbed and reflected by the lens. The law of reflection states when light reflects off a surface (like the surface of a lens) the angle of incidence is equal to the angle of reflection.

The problem with regular ophthalmic lenses is the loss of transmission of light through the lens. A high percentage of the light passing through the lenses is either being reflected or absorbed. Lenses that lack anti-reflective treatment allow more of the light to be absorbed or reflected when contacting the lens. This can lead to problems such as internal reflections, ghost images, and glare.

Why is Glare a Problem? 

Glare is a source of light that the eye is not adapted to. Examples of glare would be the oncoming headlights of a car, stadium lights, and reflections off a flat surface such as a pool of water. These sources of inadaptable light can interfere with vision, making the glasses uncomfortable to wear. Reflections from both the front and back surface of the lens can create ghost images and cause uncomfortable glare. The application of an anti-reflective treatment is the best option to maximize transmission and minimize glare.

How Does Anti-Reflection Work? 

Since light is made of different wavelengths, two or more of theses wavelengths can interact. The light can become “in-phase” – a situation when two or more wavelengths’ peaks and crests are aligned. This interaction can lead to amplification or strengthening of the light. This is called constructive interference, whereas the opposite effect happens when two wavelengths are “out of phase” – the peak of one wave is aligned directly with the valley of
another, resulting in destructive interference.

This type of interference can cancel both waves of light, which is the desired interference for successful anti-reflective action. Lens manufacturers utilize this property of light by applying different combinations of coatings and indices of lens material to provide 100% transmission through the lens.

Anti-Reflective Treatment Improves Vision 

Glare is a hazard to most people because of bright headlights from oncoming traffic when driving at night. [1] A study involving highway police officers driving with and without anti-reflective treatment showed that those wearing the AR treatment claimed improved vision during both day and nighttime driving.

Continuous sources of glare such as sitting in front of a computer screen can cause eye discomfort, eyestrain, and mental fatigue. Patients that are constantly working on a computer will benefit from AR treatment by reducing the glare from the florescent lighting that is common in this setting.

A study that was conducted by the Pacific University College of Optometry (PUCO) in 2004 aimed to assess effectiveness of anti-reflective treatment in all settings[2]. The study consisted of 100 participants who wore glasses

for more that 6 hours a day , including at least 3 hours in front of a computer. One group of patients wore AR-treated lenses on their new glasses, while another had just a hard coat treatment (scratch proof). The results showed that 86% of the participants preferred AR treatment in all settings.

You can guarantee your patient will have the best clarity and vision by eliminating reflections and glare with anti-reflective treatment on their glasses. Anti-Reflective treatment to an ophthalmic lens is the best option to ensure comfort, clarity, and value for our patients.

[1] Comparison between anti-reflection coated and uncoated spectacle lenses for presbyopic Highway patrol Trooper, Dr. William G. Bachman, OD, Dr. J.L. Weaver, Hournal of American Optometric Association. Vol. 20. N. Feb. 1999

[2] Productivity Associated with Visual Status of Computer Users, Daum KM, Clore KA, Simms SS, Journal of American Optometric Association