What takes place during pre-testing for your routine Eye Exam?

Many people are used to going through the motion of the different tests done during their eye exam visit, but many don’t know what is actually being tested. We would like to use this article to highlight some of the common tests done during pretesting.  Pretesting is usually done in a different room before the patient is ready to see the optometrist by an optometric assitant, ophthalmic technician or an optician.  Here are few of the most common eye tests done during the pretesting stage of your eye exam:

Advanced Diagnostics in Downtown Toronto

NCT (Non-contact Tonometry)

 Non-Contact Tonometry is used by eye care professionals to measure the intraocular pressure in an individual's eye. Intraocular pressure is the fluid pressure within the eye. Intraocular pressure is useful to measure because it can determine if the patient is more likely to develop glaucoma. Glaucoma is when there is damage to the optic nerve and be caused by an increased intraocular pressure. The optic nerve is responsible for transmitting images to the brain. A Non-Contact Tonometer uses a puff into the individual’s eye. It measures the intraocular pressure by the eye’s resistance to the puff.

Autorefractor

             An auto-refractor is a computer-controlled machine that is used to provided an objective measurement of a person's refractive error and a starting point for prescription for glasses or contact lenses. Refractive error is a problem with focusing light properly onto the retina due to the shape of an individual's eye. Common types of refractive error are near-sightedness, which is when you can see objects near you clearly but object far away are not clear, and farsightedness, is when you are able to see objects far away clearly but are not able to see objects up close clearly. An autorefractor works by shining light into the eye and measuring how it changes as it bounces off the ocular fundus, which includes the retina, optic disc, macula, and fovea. An image of an object is shown to the patient moving in and out of focus and a number of measurements are taken of the reflection to determine when the eye is properly focused. When these figures are put together a level of correction needed for the patient is formed.

Auto-Keratometry

            Auto-keratometry measures the anterior curvature of the cornea, which is the front of the eye. This test can be taken at the same time as the auto-refractor in some cases. An image is reflected off of two points in the cornea, and the relationship between object size, size of the image reflected and distance between the object and keratometer are all utilized to get the result of a minimum and maximum curvature valued for the cornea. This measurement helps with contact lens fittings.

Pachymetry

            Pachymetry is the process of measuring the thickness of an individual’s cornea. This measurement is taken just before the NCT is preformed. This is useful in regards to refractive surgery candidacy and certain corneal diseases.

Retinal Imaging

            Retinal imaging is an image that is taken of the inside of an individual's eye. It uses high-resolution imaging is used for the picture. This is used to assess the health of an individual’s retina. Within the picture an individual's retina, optic disk, and blood vessels can be seen. Retinal imaging is highly recommended when an individual has diabetes, since it can cause damage to the blood vessels in the retina.

To book your Eye Exam today with one of our optometrists in the Toronto Downtown area contact us at eyedocs@metroicare.com.

What are Progressive Lenses by Essilor?

Essilor - Seeing the World BetterIf you are over 40 and are experiencing gradual vision loss at distance and close ranges, chances are you are experiencing presbyopia, the common gradual loss of near and distance vision. Essilor lenses offer you more choices today than ever before. You don't have to carry a separate pair of glasses for reading or wear lined (flat top) bifocal lenses as previous generations have used. These lined (flat top) bifocals are unflattering and can be replaced with progressive lenses.

Progressive lenses offer an easy transition from distance vision, to intermediate vision and to near vision, and they supply all the in-between corrections as well. This means that instead of having just two different viewing zones such as near and distance from bifocals, progressive lenses can correct vision at multiple distances; distance, intermediate and near correction (from bottom to top). Progressive lenses ease eye strain when compared with traditional bifocal lenses, and provide a more natural vision correction.

The world's very first progressive lens, invented in 1959, was a Varilux lens. Since the first progressive lens was invented, Essilor has continued to innovate and set a new standard of performance in vision care for patients with presbyopia. Varilux lenses are one of the top prescribed progressive lens by eye care professionals around the world.

Essilor offers many options for their lens materials, each with their own advantages and disadvantages. The plastic (CR-39) lens, a 1.50 index thickness, is very affordable, has good optical clarity and is easily tinted. The polycarbonate lens, 1.59 index thickness, is the thinnest material available. They are light weight, block UV light and are the best impact resistant lenses. High index plastic lenses such as 1.60, 1.67 and 1.74, like the CR-39 lens, are great for people with high power prescriptions. They have good optical clarity and are easily tinted. Each of these lenses can also be produced in a transition lens which transitions from light to dark as the wearer goes from inside to outside.

Laser Eye Surgery

Laser Eye Surgery, Metro Eye CareLaser eye surgery is a great way to correct your vision and eliminate your dependence on glasses or contact lenses. Like all medical procedures, laser eye surgery provides benefits, but poses risks. Laser eye surgery is the most commonly practiced procedure to correct vision problems such as, myopia (near-sightedness), hyperopia (far-sightedness) and astigmatism. More recently, laser eye surgery has also been used to correct presbyopia which is part of normal aging and can also be corrected by using reading glasses.

To perform laser eye surgery, a surgeon uses a laser device to make permanent changes to the shape of the cornea. The laser used produces a beam of ultraviolet light to vaporize tissue. Surgically altering the shape of the cornea can correct mild to moderate refractive errors in most people.

PRK (Photo-Refractive Keractectomy) surgery is when a surgeon removes the outer layer of the cornea with a surgical blade or laser. The laser beam, guided by a computer, is then used to vaporize tiny amounts of tissue under the surface of the cornea. The procedure removes just enough tissue to reshape the cornea in a way that corrects your vision.

LASIK (Laser Assisted in situ Keratomileusis) surgery is more complicated. The surgeon first cuts a flap in the cornea with a very sharp blade or laser, that piece is  then lifted and a computer-guided laser is used to remove a calculated amount of tissue from the inside layers of the cornea.

Some of the risks with laser eye surgery include:

  • Pain or discomfort lasting for a few days, ranging from moderate to severe.
  • Hazy vision during the healing process, which usually clears up within the first week after surgery.
  • Regression, which in some cases can cause the eye to regress to its previous refractive error within about six months. If this happens you may need a second operation.
  • Dry eyes.
  • Poor quality of night vision due to halos and glare. Although this is a lot less common with advanced wavefront technology.
  • A serious condition called corneal ectasia, which is a weakening and bulging of the cornea.

Nikon Lenses at Metro Eye Care

Single Vision: 

Nikon lenses offer 2 types of lenses for single vision: spherical and aspheric/multi-aspheric lenses. Aspherical lenses are flatter and thinner then spherical lenses and have two distinct advantages:

  • Better vision. They have less distortion around the edges of the lenses, which allows for sharper vision.
  • A more attractive look. They have less magnification, so they have less impact on your appearance

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