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How Do We See?

eyeball drawing

Have you ever thought about how vision works? Seeing is an incredible gift made possible by a system in which the eye and the brain process visual information from the outside world. If any step of that process does not function properly, vision will be impaired.

Similar to a camera, the eye transmits light from the world around us into an image that we can perceive. Certain parts of the eye even function like the different parts of a camera such as the shutter, the lens and film (if we can hearken back to the days when we used film in cameras). Here is a quick breakdown of the fascinating way our eyes and brain enable us to see and experience the world around us:

The Vision Process

Light from an object in our field of view is gathered by the cornea which is essentially the clear “window” to our eye. The cornea then refracts the light rays through the pupil (the center of the iris where light enters the eye). The iris, which like the shutter of a camera will enlarge and shrink based on how much light is coming in, then passes the image onto the crystalline lens. Just like a camera lens, the lens in the eye focuses the light rays, projecting them to a point at the back of the eye called the retina, where the image will appear upside down. The retina contains a thin layer of color-sensitive cells called rods and cones that perceive color.

From the retina, the visual signals travel to the brain via the optic nerve. The brain receives information from both eyes and must then converge the images (and flip them right side up) to get a complete picture.

Vision Problems

A breakdown in vision can happen at any point in this process. From the muscles that control the eyes, to the parts within the eye, to the pathway to the brain. Sometimes vision impairment is due to technical problems with the eye receiving the information and passing the signal on, such as convergence insufficiency (inability to coordinate the eyes to converge on one point), myopia (nearsightedness) or cataracts (clouding of the lens).   Damage to the retina such as scarring on the macula from macular degeneration can also make vision blurry.

Other times, the eyes might work perfectly, but there is a problem with the brain interpreting the signals it receives. In these cases we can’t “see” in the traditional sense, because our brains aren’t able to properly “read’ the signals or we don’t know what we are looking at. This is the case for some learning disorders that are caused by the visual processes in the brain such as dyslexia.

As you can see, vision is quite a complicated process. A simple vision exam isn’t always able to determine vision problems, especially in children which is why it is so important to have regular comprehensive eye exams, to measure the health of the eye and all of its parts.

Thank you for trusting your eyecare with us over the years.  The Foresight Eyecare team follows the government mandate to reduce the spread of the COVID-19 pandemic.  After December 2020 announcements made by the Alberta Government, our clinic is following the revised Infection Prevention and Control policy by the Alberta College of Optometrists.

Patients interested in obtaining eye exam services or eye care products can be seen by appointment only.  Please call ahead, and staff will arrange an appointment time and ask COVID-19 screening questions.  If you have any symptoms of cough, fever, runny nose or shortness of breath, we ask that you call or e-mail us and do not attend the clinic for your scheduled visit.   Within the clinic, please wear a mask and use the hand sanitizer at reception.  Our clinic complies with the City of Calgary bylaw requiring mask covering over the age of two years old.  For patients who are unable to wear a face covering due to medical reasons, the patient can be scheduled for an appointment at a time when minimal number of other patients are in the clinic such as at the beginning or end of the day to ensure appropriate physical distancing requirements.

We are using disposable disinfectant wipes on all surfaces and devices such as front desk counters, chairs, handles in exam rooms and waiting room.  All eyewear that have been touched by patients are continually being sanitized.   Any toys and magazines are stored at this time.  Examination areas are being sanitized with hospital grade disinfectant.  Debit and credit cards but NO CASH payments will be accepted.

COVID-19 symptoms are not always obvious.  We want to fend off this pandemic and minimize risk to our patients and the Foresight staff as front line health workers.   Contact that is closer than 2 m (6 feet) is to be avoided, with barriers in place when this cannot be avoided. We choose to continue to do our work and cautiously take care of our patients with compassion, humility, gentleness, and patience.   It is a challenging and new experience for many of us, so let‘s support each other and prevent virus spread!  Beyond 2020, our focus is on take care of you and keeping Clean Hands, Clear Heads and Open Hearts.   For more information, please refer to the following web pages or phone Health Link 811.

www.albertahealthservices.ca

www.collegeofoptometrists.ab.ca

Drs. Dianna Leong, Anh Bui, Andrew Chan