Night Time Driving Difficulties

The winter months are upon us and daylight savings time is in about 2 weeks.  Several patients are beginning to bring up concerns about difficulty driving at night.  In Vancouver, night driving is even more challenging with the rain, and my patients are having trouble seeing the lines between the roads.  According to National Safety Council, traffic death rates were 3X greater at night compared to day time.

There are many factors that make night driving more difficult.  A comprehensive eye exam  will help determine these causes.

1. Refractive Error: Sometimes a small refractive change in either hyperopia, myopia or astigmatism will make all the difference in the world.  At Avenue Eyecare, we love to trial frame the prescription to see if makes any difference in your distance vision before you purchase your glasses.  It’s like trying on your glasses before you buy them.  It takes away all the guess work on how your glasses will turn out.

2. Media opacity like cataracts:  When driving at night, the pupils are usually enlarged due to your physiological response to darkness.  This allows more light to enter the eye. This is a great thing for normal people.  However, when it comes to people with cataracts, the increased amount of light gets diffracted causing haloes or glare.  If the cataracts are significant enough, a cataract consult would be warranted.

3. Corneal problems: Dry eye disease is a common condition that affects the cornea.  This dryness is exacerbated when the heater is on and may lead to reflex tearing which causes blurred vision.  Other corneal problems may include keratoconus.  Keratoconus is a corneal thinning disease and causes the diffraction of light in random directions.  This causes haloes and glare during night time driving.

4. Retinal problems:  Retinal diseases may be the cause of difficulties with vision in dim lighting.  This may include retinitis pigmentosa (night blindness disease) or macular degeneration (accumulation of waste products in the eye).  Low vision devices may be needed to help you drive.

5. Low quality lenses and coatings:  Lower quality lenses have more distortions and aberrations which cause blurred vision.  Poor quality anti-reflective coatings also tend to peel off and distort vision.  At Avenue Eyecare, if driving is your main priority, we usually recommend Essilor Varilux 360 Lenses with a Crizal Sapphire coating or  Nikon See Max Lenses with a SeeCoat Blue.  Once you try one of the high definition lenses, you’ll appreciate the clarity and brightness of your vision.

Dr. Sherman Tung, OD FAAO

drtung@avenueeyecare.com
Vancouver Kerrisdale Optometrist

Contact Avenue Eyecare to book your appointment today.

Polarized Sunglasses

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This week marks the official start of the summer season.  I’ve been getting a lot of questions about the differences between polarized and non-polarized sunglasses, so here’s the answer for all those who are curious.

Polarized sunglasses have a polarizing filter which helps reduce glare and improves the quality of your vision.  When sunlight travels through air, it eventually reaches surfaces such as cars, water, asphalt roads, etc…  The light hits theses reflective surfaces and bounces off parallel to it, usually in a horizontal orientation.  For example, when you look at the hood of a car under the sun, the glare off the surface is from reflected sunlight vibrating in a horizontal direction.  Since the majority of glare is caused from horizontally-oriented light rays, polarizing filters are set vertically so that only vertically-oriented light rays can go through the filter while horizontally-oriented light rays are blocked out.  These lenses are most beneficial to those spending time on water or those who drive because most of the glare in these cases is caused by horizontal surfaces (e.g. water and the hood of your car).

Polarized sunglasses are not recommended for golfers because some find it more difficult to read the green.  Pilots and police officers should also refrain from wearing polarized lenses because it is difficult to read LCD displays.

(Fun fact from Cheryl, our optician: if you tilt your head at 45 degrees to the right while wearing your polarized sunglasses, your LCD screens should black out.)

Dr. Jessica Chang, OD  drchang@avenueeyecare.com