Eyelab Logo

Tag: Myopia

Posted on by Dr. Sherman Tung

20/20 Vision

When having an eye exam done you might have been told that you have 20/20 vision, but what exactly does that mean? To put it simply, having 20/20 vision indicates that at a distance of 20 feet, you are able to see the smallest letters that should be seen at 20 feet. If you have 20/40 vision, it indicates that you need to be at 20 feet to see what a person with 20/20 vision can see at 40 feet. On the other hand, if you have 20/15 vision, you can see at 20 feet what a person with 20/20 vision can see at 15 feet.

How do we measure our visual acuity?

There are many ways to measure a patient’s visual acuity, but the most common way is through using a Snellen chart that presents with numerous lines of letters above one another. Letters found at the top of the chart are larger and easier to see but become smaller and difficult to read as you move down the chart. Patients are tested by covering one eye and reading the letters from top to bottom at which point they repeat these steps while covering the other eye. Afterwards, patients will use both eyes together to determine the lowest line they are able to read clearly.

Posted on by Dr. Sherman Tung

How do my eyes adjust to different lighting?

Photo by Agence Olloweb on Unsplash

Our eyes are incredible at adapting to different lighting conditions. This is done through the iris and pupil of the eye. Our pupils are the dark hole at the front of the eye which allows light to enter and form an image on the back portion of our eye. This pupil size is controlled by muscles found on the iris, which is the coloured portion surrounding the pupil. In bright sunlight, our pupils will begin to constrict, allowing less light to enter into the eye. On the other hand, when we are in a dark room our pupils will become bigger and increase the amount of light getting into the eye.

credit: https://www.sciencelearn.org.nz/resources/50-how-the-eye-focuses-light

Once the light enters through our pupil, it hits the back of our eye called the retina. The retina has two types of photoreceptors called rods and cones. Rods are responsible for night time vision and cones are responsible for day time vision. When we are in a dark room, rods are the ones that let us see.

Dark adaptation

The reason you are momentarily blind in the dark when going from a well-lit room is because it takes some time for our eyes to adjust. This is referred to as dark adaptation. During this period, the rod receptors are the key players to fully adapt and return vision to normal.

Posted on by Dr. Sherman Tung

Is it okay to buy glasses online? Do I really need an optometrist/ optician?

Photo by wu yi on Unsplash

When considering whether to buy your glasses online, at first it may seem more convenient and likely less costly. But the prescription given to you by your optometrist is only one piece of information that will determine how effective your glasses will be in improving your vision. Let’s consider the pros and cons:

Pros of buying online:

  • Wider selection of styles and colors
  • Many choices between different websites
  • Often can save on cost (but more on that later)

Cons of buying online:

  • You miss out on having a trained professional aid you in ensuring your glasses are the right fit in
    terms of comfort and effectiveness
  • Quality control of frames may often be sacrificed to maintain that low price you see online
  • Specific measurements such as PD, finding the best optical center, and measurements for
    progressives will either often be wrong or not available for online retailers
  • Prescription issues in general occur much more commonly when ordered online as opposed to
    in person

What could initially be seen as a way to save time and money in the first place may end up more costly for both in the long run if any of the above issues occur. In addition, common complaints with improperly selected glasses may include: headaches, fatigue, nausea/dizziness, eyestrain, glasses slipping off the nose, and pain/pressure marks on your nose/around the ears. Those with high prescriptions, children, complicated prescriptions, and multifocal prescriptions should especially consider in person options as opposed to online.

Posted on by Dr. Melody Tong

What does my eye prescription mean?

Photo by Josh Calabrese on Unsplash

Eyeglass and contact lenses prescriptions can contain components and abbreviations that may be harder to decipher. Here are some of the common abbreviations and what they mean:

  • OD: or oculus dexter refers to your right eye
  • OS: or oculus sinister refers to your left eye
  • SPH: is the sphere and refers to the lens power required to help correct your vision. A (-) negative
    indicates nearsightedness and (+) positive indicates farsightedness
  • CYL: is the cylinder and refers to how much astigmatism you have if any. Astigmatism is caused
    by a cornea or lens that has a different shape than normal and multiple focal points.
    Astigmatism is very common.
  • AXIS: a number between 1 and 180, indicates exactly where the astigmatism appears on your
    eye
  • ADD: stands for the additional lens power needed to make it easier for you to read. This is seen
    on prescriptions for reading glasses or the lower portion of bifocal/progressive lenses
  • BO, BI, BU, BD stand for base out, base in, base up, and base down. These refer to the position
    of the prism on eyeglasses that correct double vision

For contact lenses you may see additional information such as the brand, mode of wear, and BC +
DIA.

  • BC: The base curve is the measurement that indicates the curvature and shape of your contact
    lenses. This is taken when the steepness or flatness of your cornea is measured.
  • DIA: The diameter is the measurement of the length that your contacts need to be to
    completely cover your cornea.
Posted on by Dr. Melody Tong

Are You Ready For Your Eye Exam?

Photo by nrd on Unsplash

Having an annual eye exam is a great way to not only take care of your eyes but your overall health as well. Eye exams can detect early signs of conditions such as diabetes and high blood pressure. Here are some tips to help you make the most of your next visit!

What to think about:

  • Have I noticed any eye problems such as blurry vision, flashes of light, floaters, redness, or double vision?
  • Are my daily activities being affected by my vision?
  • How do I take care of my contact lenses or glasses
  • Have I had any surgeries or injuries in my eyes that I could let the doctor know about?
  • Any family history of eye conditions such as glaucoma?

What to bring:

  • Your current glasses or contact lenses even if you have multiple pairs for different tasks
  • A list of your medications/supplements you are taking
  • Have someone who can drive you home or a method of transportation ready for if you have your eyes dilated. This happens often in yearly eye exams and can make you sensitive to light and have blurry near vision (~4-6 hours)
  • Vision and health insurance information

Questions to ask:

  • Differences between contacts and glasses for you and how this compares to surgery options as well?
  • If anything has changed in my ocular health since the last visit?
  • What any symptoms you may have mean and what you can do to prevent them from getting worse or resolve?
  • When should I return for my next visit?

Posted on by Dr. Sherman Tung

Interested in Refractive Eye Surgery?

Photo credit: iris.ca

In the case of nearsightedness, farsightedness, astigmatism, or presbyopia refractive surgery can help either reduce or eliminate the need for glasses/contacts and improve vision. Good candidates include:

  • Patients with stable unchanging refractive errors
  • Patients with thick healthy corneas and good overall ocular health
  • Patients whose lifestyle/expectations match the surgery they choose

Candidates may have limited options or should avoid refractive surgery if they have:

  • thin corneas
  • severe dry eye
  • extreme levels of myopia, hyperopia, or astigmatism
  • corneal scars
  • cataracts
  • history of eye infections or an active eye infection
  • diabetes
  • glaucoma

What to expect with refractive eye surgery

Before your surgery, your optometrist will:

  • Discuss options and expectations associated with the different types of refractive eye surgery
  • Test your vision
  • Measure the surface and thickness of your cornea
  • Double check if any other existing conditions may complicate or prevent a successful outcome

During your surgery, your doctor will:

  • Instill numbing eye drops
  • Instill devices around your eyelids to prevent blinking
  • Have the patient will stare at a target light to prevent from moving
  • Clicking sounds, duration, other details may vary between different types of surgeries

After your surgery, you will:

  • Use a see through shield to protect your eye while it heals for a few days
  • Apply eye drops to reduce dryness and promote healing
  • Experience varying amounts of scratchy/burning sensations temporarily

Be sure to discuss with your eye care provider about the varying types of refractive surgery options and if they are right for you. Some of these include: LASIK, PRK, ICL, LRI, SMILE etc.

Posted on by Dr. Sherman Tung

Do I Need a Contact Lens Fitting?

Image by rawpixel.com on Freepik

Why do I need to be fitted for contact lenses? Did you know your glasses prescription is different from your contact lens prescription? When an optometrist fits you for contact lenses, they are ensuring several things:

  • Your eye is healthy enough to be wearing contact lenses. Conditions such as dry eyes and allergic conjunctivitis need to be treated before you can wear contact lenses. Eye conditions such as corneal scars, dystrophies, and/or irregular surfaces may require a fitting with specialty lenses.
  • The contact lens is the right type for your life style. Based on your occupation, extracurricular activities, and other needs, we can help you determine whether dailies, bi-weekly, or monthly contact lenses will meet your needs.
  • Finding a comfortable fit with good vision. We take measurements of your eyes to fit you in a comfortable lens. Many companies make contact lenses, and each have a set of parameters they work with. We can check if a lens is too tight or too loose on your eyes, how the contact lens moves when you blink, and whether it is centered on your eye. We also ensure each eye sees well both at a distance and near.

In addition, we first train new contact lens wearers on how to safety insert and remove contact lenses. We will go over the cleaning process, to ensure that lenses are handled safely because any buildup of proteins and debris on the lenses can cause damage to the cornea.

Posted on by Dr. Sherman Tung

MiSight Contact Lenses

Myopia, or nearsightedness, is a condition which causes distant objects to appear blurry. It is a particular concern with children, because myopia results in the lengthening of the eyeballs. As children’s eyes continue to grow, so does the progression of myopia. As a result, the retinal tissues gradually stretch, which can increase the risk of eye diseases later in life. Luckily, CooperVision’s MiSight 1 day lenses are an effective and child-friendly solution to managing myopia progression!

Source: CooperVision

How do they work?

The MiSight 1 day lenses are the first soft contact lenses proven to slow down the progression of myopia, through the use of ActivControl technology. When inserted on the eye, the center of the lens improves distance vision by correcting the refractive error and the concentric peripheral rings allow for myopic defocus. This defocusing is what is believed to reduce further lengthening of the eyeball, effectively impeding the progression of myopia. Not only have the MiSight 1 day lenses been clinically proven to slow down the progression of myopia by 59%, they are also comfortable to wear and easy to handle. In a three-year long study conducted on the MiSight 1 day lenses on children ages 8 -15 years, 90% of children reported that they preferred their MiSight 1 day lenses compared to their glasses and 90% of children were able to insert and remove the lenses on their own. Further, 100% of parents stated that their children were happy with their overall experience with the MiSight 1 day lenses, including the comfort, vision, ease of use, and freedom from glasses!

Curious to see if MiSight lenses are right for your children? Book an appointment with Eyelab to chat with one of our doctors. You can also get in touch by calling us at +1 (604) 260-1166 or via email at frontdesk@helloeyelab.com.

Dr. Sherman Tung

Dr. Sherman Tung
OD FAAO FIAOMC

Optometrist | Orthokeratology + Myopia Management
T 6042601166
E drsherman@helloeyelab.com

Posted on by Dr. Sherman Tung

Progent – The Diligent Contact Lens Cleaner

Are your ortho-K contact lenses or RGP lenses are starting to get irritating and uncomfortable? Ever feel like there is a foggy blur over your vision? Looking for an easy and effective way to deep clean your lenses? Here at Eyelab, one of our staff’s favourite products is the Progent Lens Cleaner.

How does it work?

Progent cleans lenses by loosening and removing protein deposits that build up on our contact lens over time. It effectively removes surface proteins on all ortho-K contact lenses and RGP lenses without the need for manual rubbing, which may damage the lenses. This product not only improves the comfort of lens-wear, it also helps maintain eye health and prolongs the life of your lenses. Progent deep cleans lenses much more effectively than daily cleaning products.

It comes with two solutions: Progent A (sodium hypochlorite) and Progent B (potassium bromide), which work together in an oxidation-reduction reaction to deep clean surface coatings without the abrasives or mechanical rubbing used in typical cleaning. In just thirty minutes, it effectively disinfects against all organisms that are likely to contaminate lenses, including yeast, mold, bacteria, and viruses.

Source: Menicom.com

At this point, you may be wondering how many complicated steps come with this cleaner? The easy answer is, just mix the A and B solutions, shake, and wait! Simply soak your lenses for 30 minutes – no rubbing required. By using this cleaner every 3 months (or more frequently if needed), your contact lenses can stay polished and well-maintained to better serve your vision.

Posted on by Dr. Sherman Tung

8 Years Post PRK Laser Eye Surgery

In a previous post, I talked about my experience with laser eye surgery in 2014. Now, eight years later, I am extremely happy about my decision to undergo the surgery. My vision is still stable at 20/20 however I still experience dry eye from time to time.

One of the biggest pros of the surgery is being able to wake up in the morning and immediately see clearly. This surgery allowed me to tend to my twin daughters better in the middle of the night without having to find my glasses first. I also no longer have to worry about getting my contacts or glasses coming out when playing ultimate frisbee or during other physical activities. A smaller change in my life that I started to appreciate after the surgery was that I longer need to carry around microfiber cloths to clean my glasses.

However, now that I am reaching the age in which the effects of presbyopia (the gradual loss of your eyes’ ability to focus on nearby objects) becomes more prominent, I may need to use reading glasses. Overall, I am very glad I decided to get PRK and I have no regrets about it!

Book an appointment at Eyelab to learn more about whether you’re a candidate for laser eye surgery, and to discuss any questions or concerns you may have!