Month: July 2017

Middle-aged people are plagued by reading difficulties named presbyopia. As mentioned in the previous passage, near blur is a normal age-related change and currently there is no way to stop it from coming.

Also reading or wearing glasses will not speed up or slow down the presbyopia process. So once we have presbyopia, what can we do to restore our reading vision? What are the differences between various presbyopia corrections such as reading glasses and progressive glasses? Is there any refractive surgery targeting reading difficulties? Now let us take a look.

Reading Glasses

Glasses are the easiest way to correct near vision. There are different types of glasses suitable for people with various vision needs. These glasses are mainly classified into single vision, bifocals and progressives.

1. Single vision glasses

Single vision reading glasses can correct vision at a single distance only. For example, a pair of single vision reading glasses allow you to read at 40cm but will not work for walking or watching television.

Even worse, if you have several near tasks with different working distances, such as needle work at 30cm, reading at 40cm and using computer at 50cm, you probably need few pairs of single vision reading glasses.

2. Bifocal Glasses

Bifocal lenses incorporate distant and near prescription into a single pair of glasses. Generally the majority portion of the bifocal lens is corrected for distant and there is a small segment at the bottom of the lens corrected for near vision.

It is more convenient than single vision lenses but the reading segment looks obvious and cosmetically does not look good. Also, the intermediate vision usually remains uncorrected when you wear bifocal glasses, such as the vision for computer, painting and reading musical notes.

3. Progressive Glasses

Progressive lenses are similar to bifocal lenses that the majority portion of the lens is corrected at far distance and a small reading area at the bottom. However, there is a corridor which
progressively changes its power and allow a gradual transition from distant prescription to near prescription. Therefore besides far distance and near, it also corrects wearers’ intermediate distance vision.

Also, there is no obvious segment on progressive lenses which makes them cosmetically better than bifocal lenses.  But progressive glasses require longer adaptation time than single vision and bifocal glasses. Despite that, according to the American Optometric Association, many people with presbyopia still prefer progressive glasses more than the other types of glasses due to the convenience. In addition, currently there are new generation of progressive lenses which have better lens designs to widen the wearers’ field of view and make it easier to adapt.

Contact Lenses

For contact lens wearers correcting presbyopia, they can correct one eye for distant prescription and one eye for near so that they can see both at the same time. But this will sacrifice their binocular vision especially when their presbyopia is more established.

They can also choose for multifocal contact lenses which can correct both distant and near vision for both eyes at the same time. Nevertheless, the visual outcome is limited by environmental light intensity and the majority of multifocal contact lenses do not correct astigmatisms.

Elderly Vision Problem

Refractive Surgery

Patients can also undergo refractive surgery such as LASIK to correct reading difficulties, and the correction will be similar to that of contact lenses — one eye for distant and near vision respectively. Another surgical approach will be leaving both eyes with low degree of shortsightness.

The near vision after surgery will be acceptable but the distant vision will be blurry which the patient may need glasses at far distance. On the other hand, unlike contact lenses, refractive surgery is an irreversible process. Patients also have to bear the surgery risks such as overcorrection, under-correction, induced astigmatism and regression. Patients are advised to try contact lenses to mimic the correction outcome before doing the surgery.

No matter which options you consider for your reading difficulties, it is still important to date your optometrist, at least once a year, for comprehensive eye examinations.

By Jeff Tang, Registered (Part I) Optometrist

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Eyecare information by Swisscoat Vision Centre
Address : 23/F Whole Floor, One Midtown, 11 Hoi Shing Rd, Tsuen Wan, N.T., HK
Appointment :+852 2751 8491
Website : www.swisscoat.com

In 2012, World Health Organization (WHO) has summarised various population-based vision screening surveys from 39 countries worldwide, and estimated that 285million of the people in the world are visually impaired (defined as having presenting vision equal to or less than 30% of normal vision), while 39million are blind (defined as having presenting vision equal to or less than 5% of normal vision). Such figures showed that there are still large numbers of people live under darkness.

2017 World Sight Day

Every second Thursday of October has been named as World Sight Day since 2000 (10th of October will be the World Sight Day of 2017).

From September to October, International Agency for the Prevention of Blindness, WHO and other organisations will hold a series of events to raise public awareness of vision impairment and blindness as major international public health issues. The international key messages they would like to deliver this year are as follows:

• Approximately 285 million people worldwide live with vision impairment. Of these, 39 million people are blind and 246 million have low vision
• 90% of blind people live in low-income countries
• 80% of visual impairment is avoidable, readily treatable and/or preventable
• Restorations of sight, and blindness prevention strategies are among the most cost-effective interventions in health care
• The number of people blind from infectious causes has greatly reduced in the past 20 years
• An estimated 19 million children are visually impaired
• About 65 % of all people who are visually impaired are aged 50 and older, while this age group comprises only 20% of the world’s population
• Increasing elderly populations in many countries means that more people will be at risk of age-related visual impairment.

Orbis and Darkness to Go Campaign

Orbis is an international non-profit non-governmental organization. Its mission is to eliminate preventable blindness. It also aims at enhancing the skills of eye care personnel in developing countries, in a bid to enable the local partners to know how to provide affordable, convenient, and sustainable quality eye care services.

Since 1982, Orbis has carried out programs in 92 countries, provided treatment to more than 23.3 million blind and visually impaired people, and enhanced the skills of more than 325,000 eye care professionals.

Each year, Orbis will hold different events in Hong Kong and worldwide from September to October for supporting the World Sight Day.

Darkness to Go Campaign is one of the events. During this campaign, different shopping malls, retailers and manufacturers will select “items in black” for charity sales, and donate part or all of the sales proceeds to Orbis.

Swisscoat Vision Centre is always concerned with your eye health and hopes to use this opportunity to restore vision to the blind by supporting Orbis Darkness to Go campaign.

Swisscoat will donate $50 for every purchase of Swisscoat Transitions StressFree SF Blue-Light Filtering Lenses in Swisscoat Vision Center during the campaign period from September 1 to October 12, 2017. Hope you all can actively participate in this charity event, and bring light to those who are in need for help.

By Paco Chan, Registered (Part I) Optometrist

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Eyecare information by Swisscoat Vision Centre
Address : 23/F Whole Floor, One Midtown, 11 Hoi Shing Rd, Tsuen Wan, N.T., HK
Appointment :+852 2751 8491
Website : www.swisscoat.com

In my previous blog entry, I have listed out and explained different myopia control methods which are with scientific evidence. In this entry, I will further talk about the procedures and precautions of prescribing and using ortho-k lens respectively.

The Procedures of Prescribing Ortho-k Lens:

1. The optometrist will help the patient perform a comprehensive ortho-k assessment which includes conreal and tears quality assessment, corneal topography assessment, and getting the patient to wear the ortho-k trial lenses. After the assessment, the optometrist will decide whether the patient is suitable to wear the ortho-k lens from both mental (especially kids) and physiological perspectives.
2. Once the optometrist deems that the patient is suitable to start the procedure, an informed consent will be signed by the optometrist, and the wearer or the parents of the wearer. A pair of ortho-k lenses will then be ordered. Most ortho-k lenses have to be ordered from overseas, it usually takes around two weeks to get the lenses.
3. During the ordering period, the wearer will learn how insert, remove, handle and clean the ortho-k lens properly. The learning period differs between people. Some kids can get the techniques within 2-3 lessons, while some nervous patients may take more than 5-6 lessons to handle it.
4. Before getting the lenses, the optometrist will do the final on-eye contact lens fitting check. If everything is fine, the ortho-k lenses will be delivered.
5. Due to the fact that ortho-k lenses are worn during sleeping, it is of higher risk when compared to daytime contact lens wear. It is necessary to have frequent follow-up visits especially at the beginning of lens wear. An early morning visit (within 2 hours after waking up) after wearing the lenses in the first overnight is needed. Following successful first overnight lens wear, follow up visits will be performed after 1 week, 2 weeks, 1 month, and then every 3-4 monthly.
6. An annual replacement of the pair of ortho-k lenses is also needed. It is because the curvature of the lenses may change with everyday wear. Besides, deposits will accumulate on the ortho-k lens surface. The deposits will lower the oxygen transmissibility of the lenses and increase the chance of having corneal infection. Therefore, annual replacement of ortho-k lenses is necessary.

The Precautions of Using Ortho-k Lens:

During ortho-k lens wearing, if you experience severe red eye, eye pain, photosensitivity and excessive tearing, you should stop lens wear and contact your optometrist immediately.
If you catch a cold, get a fever, or have to go to other places where there is no accessible clean water supply, you should temporarily stop wearing the ortho-k lenses and tell your optometrist accordingly.
If your kids are unable to clean and handle the lenses by themselves, or parents/guardians are unable to do so. Under such circumstances, I do not suggest your kids to perform orthokeratology.
Finally, if you want to get your kids to try orthokeratology, I would recommend you to find the optometrists who are qualified and experienced in doing so. Furthermore, parents should understand your responsibility in complying with the advice and instructions given by the optometrist. By doing so, orthokeratology can then be practised safely.

By Paco Chan, Registered (Part I) Optometrist

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Eyecare information by Swisscoat Vision Centre
Address : 23/F Whole Floor, One Midtown, 11 Hoi Shing Rd, Tsuen Wan, N.T., HK
Appointment :+852 2751 8491
Website : www.swisscoat.com

In recent years, digital devices have dominated our everyday lives. Concerns about the potential health hazards arise with the coming of this digital era.

One of the hot topics is the potential damage to the retina caused by blue light emitted by electronic devices, and subsequently, numerous anti-blue light products have been introduced to the market. Let’s take a deeper look into these blue lights and how can we protect our eyes better.

What is Blue Light?

The visible light we seen is actually a wave that is comprised of different colours of light such as red, yellow, green and blue.

At the same time, the energy carried by the wave is inversely proportional to its wavelength. Therefore, the red side of the visible light which has longer wavelength carries less energy, while the blue side which has shorter wavelength carries more energy. That’s why blue light is also called ‘High energy visible light (HEV)’.

Before the digital era, we were already exposed under blue light coming from its natural source: sunlight. Nowadays we are bombarded with more artificial blue light sources in our daily lives including the display screens of smartphones, computer, laptops and other digital devices as well as energy-efficient lighting such as LED light.

These devices emit higher intensity blue wavelength than other wavelengths. Despite the fact that the artificial blue light intensity is still a lot weaker than sunlight, people are now spending longer time in close proximity with electronic devices which intensifies the blue light exposure, creating tangible health concerns.

Visible light spectrum. Image adopted from: http://www.allaboutvision.com/cvs/blue-light.htm

Blue Light is Both a Blessing and a Curse

As the awareness towards blue light increases, people have been trying to avoid as much blue light as possible. However, suitable amount of blue light is essential to our vision and health. First, blue is one of the 3 primary colours forming our colour vision.

Completely removing blue colour will make everything yellowish and distort our colour perception. Second, blue light perception helps people maintaining alertness and memory. Appropriate amount of blue light is also crucial to regulate our biological clock, but excessive blue light before sleep can disrupt it.

Since blue light carries higher amount of energy, people postulate that blue light can potentially damage retinal cells. Some animal studies demonstrated that excessive exposure under blue light could result in cell injury at the retina.

Other researchers also pointed out that blue light exposure may increase the risk of having age-related macular degeneration (AMD) which can lead to severe vision loss, but it is still waiting stronger evidence to prove so. On the other hand, blue light scatters more easily than other light colours. The scattered blue light emitted from digital screens degrade visual signal and may result in eyestrain.

High Energy Blue Light VS Blue Colour VS Blue Colour Light

High energy blue light may be potentially harmful to our eyes. But some may also wonder if blue colour objects are also being harmful. Actually the harmful blue light refers to the high energy short wavelength with strong light intensity coming from the light source.

A blue object merely reflects blue wavelengths in a random direction when light shines on it. It will not emit light by itself and the blue wavelength reflected has low energy intensity.

How about blue colour light? That would depend on the light source. If it is formed by normal white light but with a blue filter, the blue filter only allows blue wavelength to pass through but it will not increase the amount of blue wavelength.

Looking at light with blue filter will not increase the amount of blue light entering the eye compare to without the filter. If it is an LED light source, it will still emit high energy blue light even the light looks white.

Spectral power distributions of daylight and white LED. Image adopted from: https://www.slrlounge.com/gear-review-fiilex-led-light/

Protecting our Eyes From Harmful Blue Light

In the modern world, it is practically impossible to stay away from all blue light sources. In our retina, retinal pigment and cell metabolism give partial protection from blue wavelength. The next generation of LED light also attempts to reduce its blue light emission. But in order to avoid receiving too much blue light, it is better to use protective products.

However, it is not as simple as using anti-blue filter to cut away all blue light otherwise it will disrupt visual and cognitive function as well as the biological clock. There are some ophthalmic lenses in the market which can block the excessive HEV lights without altering the visual performance, night vision and sleep quality as proven by research studies.

Also, appropriate blue-blocking lenses cut away the scatter-prone blue lights and help reducing eyestrain when using digital devices. However, blue-blocking lenses give slightly more yellowish vision which may be significant for designers and artists. But generally it will not affect colour perception much.

By Jeff Tang, Registered (Part I) Optometrist

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Eyecare information by Swisscoat Vision Centre
Address : 23/F Whole Floor, One Midtown, 11 Hoi Shing Rd, Tsuen Wan, N.T., HK
Appointment :+852 2751 8491
Website : www.swisscoat.com

When You Have Reading Difficulties, Find A Qualified Optometrist For a Comprehensive Eye Exam. When the 40s call, no matter how much effort and money you spent to stay young and healthy, you may still find your eyesight being not as good as before. This is particularly more obvious when you read your newspaper or mobile phone. When you start experiencing a reading problem, you may wonder if it is because of lacking enough rest.

Reading Difficulties

But soon you know there is a true near blur and you start magnifying the small words, turning on the lights and read as far away as you can…until they still can’t solve your near blur. Is reading difficulties an eye disease? Will the near blur deteriorate or improve later?

Will normal aging cause difficulty in reading? What should I do to restore my near vision? There may be hundreds of doubts coming to your mind. It’s high time to know more about your change at near vision and how can you solve the reading difficulties.

Vision Test – A Simple Way To Test Your Near Vision

First, keep the following passage away from your eyes for around 40 cm with your glasses (if needed). Then, try to read the passage. If you find it difficult to focus and you can hardly recognise the words, you may probably having reading difficulties! You can also try out the new reading difficulties online test offer by SWISSCOAT

Presbyopia : An Inevitable Near Blur On Aging Eyes

Your reading problem is officially called presbyopia. According to the American Optometric Association, presbyopia is a natural age-related change on your eye and it is not regarded as an eye disease. During reading, a special group of eye muscles called ciliary muscles will contract and change the eye lens focus which allow you to read close.

However, ciliary muscles get weaker and lens grows thicker continuously since birth. These changes gradually decrease your eyes’ ability to focus and cause your reading problem when you enter your fourth decades of life. Also, your eyes are under greater stress when you read smaller, closer, and in a dimmer environment. When you avoid doing them, reading is slightly less difficult. People over 50s will 100% get presbyopia. This kind of near blur cannot be prevented and will not be recovered.

Therefore you don’t need to be over-panic about your normal aging-eye-related reading difficulties. At the same time you also don’t need to avoid reading to prevent further drop of your near vision because the near blur change is unstoppable.

Solving Your Reading Problem

Whenever you have questions about your eyes, seek your optometrist’s advice! Usually everybody’s eyes are different and they require different near vision corrections.

Optometrists will undergo a detailed eye exam to examine your reading vision and provide useful opinion about your reading difficulties. Therefore before buying ready-made reading glasses or borrowing your friend’s reading glasses to solve your near blur, make an appointment for an eye exam first! In the next passage, treatment options towards presbyopia will be discussed.

By Jeff Tang, Registered (Part I) Optometrist

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Eyecare information by Swisscoat Vision Centre
Address : 23/F Whole Floor, One Midtown, 11 Hoi Shing Rd, Tsuen Wan, N.T., HK
Appointment :+852 2751 8491
Website : www.swisscoat.com