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Your Family Eye Care Center – Located in the plaza of Walgreens & JCPenney

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Home » Eye Library » Your Eyes and Vision » How the Eye Works

How the Eye Works

Our ability to “see” starts when light reflects off an object at which we are looking and enters the eye. As it enters the eye, the light is unfocused. The first step in seeing is to focus the light rays onto the retina, which is the light sensitive layer found inside the eye. Once the light is focused, it stimulates cells to send millions of electrochemical impulses along the optic nerve to the brain. The portion of the brain at the back of the head interprets the impulses, enabling us to see the object.


Light, refraction and its importance.
Light entering the eye is first bent, or refracted, by the cornea — the clear window on the outer front surface of the eyeball. The cornea provides most of the eye’s optical power or light-bending ability.


After the light passes through the cornea, it is bent again — to a more finely adjusted focus — by the crystalline lens inside the eye. The lens focuses the light on the retina. This is achieved by the ciliary muscles in the eye changing the shape of the lens, bending or flattening it to focus the light rays on the retina.


This adjustment in the lens, known as accommodation, is necessary for bringing near and far objects into focus. The process of bending light to produce a focused image on the retina is called “refraction”. Ideally, the light is “refracted,” or redirected, in such a manner that the rays are focused into a precise image on the retina.


Most vision problems occur because of an error in how our eyes refract light. In nearsightedness (myopia), the light rays form an image in front of the retina. In farsightedness (hypermetropia), the rays focus behind the retina. In astigmatism, the curvature of the cornea is irregular, causing light rays to focus to more than one place so that a single clear image cannot be formed on the retina, resulting in blurred vision. As we age, we find reading or performing close-up activities more difficult. This condition is called presbyopia, and results from the crystalline lens being less flexible, and therefore less able to bend light.


Since changing the apparent refraction of the eye is relatively easy through the use of corrective spectacle or contact lenses, many of the conditions that contribute to unclear vision can be readily corrected.


How do we make sense of light?
Sensory interpretation
Even with the light focused on the retina, the process of seeing is not complete. For one thing, the image is inverted, or upside down. Light from the various “pieces” of the object being observed stimulate nerve endings — photoreceptors or cells sensitive to light — in the retina.


Rods and cones
Two types of receptors — rods and cones — are present. Rods are mainly found in the peripheral retina and enable us to see in dim light and to detect peripheral motion. They are primarily responsible for night vision and visual orientation. Cones are principally found in the central retina and provide detailed vision for such tasks as reading or distinguishing distant objects. They also are necessary for color detection. These photoreceptors convert light to electrochemical impulses that are transmitted via the nerves to the brain.


Millions of impulses travel along the nerve fibers of the optic nerve at the back of the eye, eventually arriving at the visual cortex of the brain, located at the back of the head. Here, the electrochemical impulses are unscrambled and interpreted. The image is re-inverted so that we see the object the right way up. This “sensory” part of seeing is much more complex than the refractive part — and therefore is much more difficult to influence accurately.


What is 20/20 Vision?
You may be pleased to hear that you have 20/20 vision and think you have perfect vision. But do you?


Not necessarily. 20/20 only indicates how sharp or clear your vision is at a distance. Overall vision also includes peripheral awareness or side vision, eye coordination, depth perception, focusing ability and color vision.


20/20 describes normal visual clarity or sharpness measured at a distance of 20 feet from an object. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance. If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.


Is 25/25 vision better than 20/20?
No. 25/25 means normal sharpness of vision, or visual acuity, at 25 feet just as 20/20 indicates normal vision at 20 feet.


Why do some people have less than 20/20?
The ability to see objects clearly is affected by many factors. Eye conditions like nearsightedness, farsightedness, astigmatism or eye diseases influence visual acuity. Most people with vision slightly below 20/20 function very well, whereas some people who have better than 20/20 vision feel that their vision is not satisfactory. Everybody’s visual expectations are different and satisfactory vision is far more complex than just being able to see 20/20.


If my vision is less than optimum, what can I do?
A comprehensive eye examination will identify causes that may affect your ability to see well. We may be able to prescribe glasses, contact lenses or a vision therapy program that will help improve your vision. If the reduced vision is due to an eye disease, the use of ocular medication or other treatment may be needed. If necessary, referral will be undertaken if an eye disease is found which warrants further investigation.

In the wake of the latest recommendations from the Center for Disease Control and the World Health Organization, we wanted to make you aware of new procedures taking place at Maple Grove Vision Clinic, effective immediately.

HOURS OF OPERATION: We will be open Mondays – Thursdays from 12:00p-5:00p. If you currently have a scheduled appointment outside those hours, our staff will contact you to see how we can best meet your needs.

EMERGENCY VISION ISSUES: It’s extremely important not to neglect your vision needs during this time, so please don’t hesitate to call to schedule an appointment during the above hours in the event of injury, redness, discharge, possible infection, etc.

ROUTINE APPOINTMENTS: Currently, we are scheduling for routine exams for *after* April 6th. If you have a routine appointment already scheduled between now and April 6th, our staff will be contacting you to discuss your needs and how we can best meet them.

GLASSES OR CONTACTS (PREVIOUS ORDERS): You’ll get a call from our front desk (as always) when your glasses or contacts are ready for pickup, and you can stop in during our open hours (above) to pick up your orders. We can arrange free shipping as needed, although glasses are always best when we can fit them to you, in-person. Please call to discuss options.

NEED MORE CONTACTS? We need your business in order to stay in business, and we’re happy to re-fill orders for contacts and ship directly to your home for free.  Just call during our business hours to order or you can also go to our website www.maplegrovevisionclinic.com to order as well.

HOW TO REACH US: Call 763-420-8030 during business hours, or email us at drfrick@maplegrovevisionclinic.com

The health and safety of our patients has always been a top priority. As a reminder, here are the actions we take whenever a patient is in our office:

ONGOING SAFETY MEASURES:

NEW SAFETY MEASURES:

HOW YOU CAN HELP:

Please do not come in to our office if you’ve traveled out of the country in the last 14 days, have any symptoms of flu-like or respiratory illness, or have had known contact with anyone who has exhibited such symptoms or tested positive for the coronavirus. As noted above, we are happy to ship any orders directly to your home, or work with a family member to make sure your vision needs are being met.

We will continue to give (and follow) recommendations based on the evidence we have on safe delivery of eye care in a time of uncertainty.  We appreciate your continued support and understanding.

Sincerely,

Dr. Scott A. Frick and staff at MGVC

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Dear Patients- Our hours are changing during this two week period.

Starting Monday March 23rd we will have hours of 12-5 Monday through Thursday.

We are still closed March 20th, 27th and April 3rd. We will start back with regular business hours starting April 6th.