Driving vision

Some people approach eye examinations with a high level of apprehension. This is common leading up to the renewal of a driver's licence. Our independence is closely linked with driving ourselves. Combine this with our locality, even with its recently expanded Warkworth bus service. I often hear declarations like ‘It would be terrible if I couldn’t drive; I couldn’t continue to live where I am.‘

I don’t have any secret loophole to share with you. I know I may lose some readers when I talk frankly about the topic of not being able to drive due to failing eyesight. For an optometrist, it is a difficult job to tell someone that they do not meet the vision standard for driving anymore. A part of our job we don’t enjoy. It is worth talking about this. Take the approach, "Prepare for the worst, hope for the best."

The most common cause of reduced vision is Age-Related Macular Degeneration. One of the risk factors for Macular Degeneration (MD) is ageing. So every year we get older, the likelihood of developing MD increases. Fortunately, in most cases MD, described as Dry MD, is slow to advance. In this context, there is time for adjustment and learning.

Two other common age-related eye conditions are cataracts and glaucoma. Cataracts are, in the majority of cases, treated with surgery, successfully restoring vision. Glaucoma, like MD, causes slow deterioration over years, which gives time to adjust.

There are some useful facts worth knowing. Every time we renew our driver's licence our vision is checked, typically every ten years until the age of 75 years. At this point, we need a GP assessment. Your GP will include a vision check as part of their assessment. From 80 years onwards, we have to renew our licence every two years, involving a GP check each time.

You can have reduced vision in one eye, or completely lose vision in one eye, and still be able to drive a car. Fun fact: One in ten people have reduced vision in one eye, sometimes lifelong.

We check two things to issue an ‘Eyesight certificate for driver licence’. The first is reading letters on the chart, and the second is an assessment of peripheral vision.

So how do you prepare, or get your head around the idea of no longer holding a driver's licence? Here are my suggestions.

Talking about options in a positive way can help. Often we make the same trips in our car, usually following predictable routes (e.g. the supermarket, or family, or sports and clubs). Generating some alternatives around these routine activities helps. Some examples; online grocery shopping deliveries or accepting a ride from a friend or neighbour can be fun and social.

Investigate other options such as taxis or Driving Miss Daisy. There is a cost, but most people are unlikely to reach the same annual spend on taxis compared with the annual cost of owning, registering, insuring, and maintaining a car. Vouchers are available for subsidized taxi trips for people with low vision.

Observe how often you might currently give a ride to other people. Most of us are happy to help friends and neighbours, and genuinely enjoy doing this. One day you might be on the other side of this arrangement. So enjoy the positive feelings when you are in the role of the helper. One day you might be giving someone else that satisfaction.

If you have macular degeneration or glaucoma what should you do? Talk with us about the changes in your vision and how this might effect your driving now, or in the future. In many cases macular degeneration and glaucoma cause very slow deteriotation and people can conintue driving.

Nick Lee presents at International Myopia Conference

We have been following Nick's progress since he won our McDonald Adams Science Scholarship in 2013 in his final year at Mahurangi College. He succeeded in gaining entry to the Optometry course at Auckland University and Nick has one year left to complete his degree. 

Nick recently attended the International Myopia Conference in Birmingham to present the results of his research. The project was titled "Effect of Atropine on Human Multifocal Electroretinogram Responses to Defocus."

Myopia (short-sightedness) is a growing epidemic across the globe. It is predicted that 50% of the world’s population will be myopic by 2050. The optometric community has employed several strategies to slow progression of myopia - myopia control.

One myopia control option is Atropine eye drops. Atropine usually acts as a muscarinic receptor blocker, forcing the eye's focussing system to relax. Its mechanism of slowing myopia progression is not known. 

Previous studies have shown electrical responses from the retina. Nick's study measured these to find out if this is where atropine is acting.

Compared to eyes with clear focus (know as emmetropia) positive defocus increases the signal; negative defocus decreases the signal. A positive defocus is protective against myopia progression; negative defocus accelerates myopia progression.

This study found atropine to enhance only the positive (protective) component of this electrical response in the peripheral retina. Although a full model is still not able to be formed, this finding is very interesting and  fits in well with other literature presented at the International Myopia Conference.

Nick's scientific poster presented at the International Myopia Conference (Birmingham, 2017) by Nick Lee, Safal Khanal, Phillip Turnbull and John Phillips. For more information please contact: nlee785@aucklanduni.ac.nz.

Research into Digital Artifical Light

A new study* highlights the disruption to sleep patterns which can be caused by blue light emitted from digital devices. 

The study, at the University of Houston College of Optometry, had people wearing blue blocking filters before bed. Participants still performed their usual nightly digital routine. Results showed a 58% increase in night-time melatonin levels. Melatonin is the chemical that signals your body its time to sleep. These melatonin levels were higher than would be achieved taking over-the-counter melatonin supplements.

“The most important takeaway is that blue light at night time really does decrease sleep quality. Sleep is very important for the regeneration of many functions in our body,” said Dr. Ostrin, from University of Houston College of Optometry.

The 22 study participants wore sleep monitors 24 hours a day. They reported sleeping better, falling asleep faster, and even increased their sleep duration by 24 minutes a night.

The largest source of blue light is sunlight, but it's also found in most LED-based devices. Blue light boosts alertness and regulates our internal body clock, or circadian rhythm, that tells our bodies when to sleep. This light activates photoreceptors, called intrinsically photosensitive retinal ganglion cells (ipRGCs), which suppresses melatonin.

Dr. Ostrin recommended limiting screen time, applying screen filters, wearing computer glasses that block blue light, or using anti-reflective lenses to offset the effects of artificial light at night time. Some devices have night mode settings that limit blue light exposure.

“By using blue filtering lenses we are decreasing input to the photoreceptors, so we can improve sleep and still continue to use our devices" she said.

Closer to home we are dispensing blue coating on lenses. This coating improves comfort looking at screens. Wearers also find the blue coat is good for driving. Blue light causes light scatter so in daylight conditions blocking this reduces glare. Please contact us if you have any questions about lens coating options.

*Study published in Ophthalmic & Physiological Optics.

Myopia Management - Ortho-K

Managing Myopia

Myopia  (short sightedness) occurs when the eyeball is too long or too powerful resulting in blurred distance vision. People with myopia are unable to read the board at school, or need glasses for driving. Vision for near objects is clear, within a close range.  Once someone becomes myopic their vision tends to get worse over time and glasses and contact lenses become stronger. The greatest change is usually in childhood and teen years.

Why do we need to control myopia?
High levels of myopia are associated with increased risk of eye diseases such as glaucoma, cataracts, retinal detachment and macular degeneration later in life.

Can you (really) slow or stop myopia?
Yes! Most people can slow down or stop their eyes from becoming more myopic. This is exciting news which resonates with all parents who are short sighted.

What causes myopia development and progression? 
Genetics, individual characteristics and environment. 

In the last 10 years, there has been considerable research into finding the environmental factors which cause myopia progression. Much has been learned from work in animal models. Current understanding is the stimulus to axial elongation—and hence to myopia progression—is defocus not in the central retina but in the mid-periphery. In experimental models, peripheral focus has emerged as very important.

Optometrists can help reduce progression of myopia. We evaluate the whole clinical picture, measuring vision and prescription, recording family history, understanding reading habits and outdoor activity. There are different options to correct vision. Research shows us how each option will influence myopia development. We can intervene and hopefully stabilize vision changes

Techniques include progressive/bifocal glasses with reading power, multifocal soft contact lens, prescription eye drops and Ortho-K contact lenses to reshape the eye. When we have completed an eye examination we can discuss each of these options in full.

Orthokeratology (Ortho-K)

Ortho-K is the use of specially designed rigid contact lenses worn overnight. The contact lens gently reshapes the cornea giving clear vision the following day without contact lenses or glasses. The effect of the lenses is temporary, giving  a day of clear vision and lenses need to be worn every night. (If the lenses are not worn at night, vision will be blurred again the next day).

Overnight Ortho-K lenses produce a corneal shape that seems to be ideal for preventing axial length progression. Ortho-K makes use of “reverse geometry” lenses that are relatively flat in the center. Wearing these lenses at night causes the cornea to become temporarily flat centrally and a little steeper in the mid-periphery. As a result, the Ortho-K produces focused central and mid-peripheral images, which is useful for myopia control.

Although RGP lenses are not known for being comfortable, Ortho-K lenses are worn only at night when sleeping, so there is no discomfort from lens-lid interaction. These are large lenses that don’t move on the eye and provoke sensation. In addition, the materials used are highly oxygen permeable.

Ortho-K is very satisfying for the practitioner. For many children, getting out of glasses gives a big boost to self-esteem; and their parents are thankful to be doing something positive for their children by reducing their myopic progression. Among kids who are active, Ortho-K is safer than glasses for contact sports and safer than ordinary contact lenses for swimmers. Myopia control is just one of many positive benefits of Ortho-K.