EYE ANATOMY :
The eye is our organ of sight. The eye has a number of components which include but are not limited to the cornea, iris, pupil, lens, retina, macula, optic nerve, choroid and vitreous.
1. DEFECTS OF THE EYE:
- Myopia: (nearsightedness) This is a defect of vision in which far objects appear blurred but near objects are seen clearly.
The image is focused in front of the retina rather than on it usually because the eyeball is too long or the refractive power
of the eye’s lens too strong. Myopia can be corrected by wearing glasses/contacts with concave lenses these help to focus the i
mage on the retina.
- Hyperopia: (farsightedness) This is a defect of vision in which there is difficulty with near vision but far objects can be seen easily.
The image is focused behind the retina rather than upon it. This occurs when the eyeball is too short or the refractive power of the lens is too weak.
Hyperopia can be corrected by wearing glasses/contacts that contain convex lenses.
- Astigmatism: This defect is when the light rays do not all come to a single focal point on the retina,
instead some focus on the retina and some focus in front of or behind it. This is usually caused by a non-uniform curvature of the cornea.
A typical symptom of astigmatism is if you are looking at a pattern of lines placed at various angles and the lines running in one direction appear
sharp whilst those in other directions appear blurred. Astigmatism can usually be corrected by using a special spherical cylindrical lens;
this is placed in the out-of-focus axis.
- Presbyopia: is a visual disorder that affects anyone between the ages of 40 and 45. This is when close-up objects become blurry. To be able to read, you may have to stretch your arms to move the book away from your eyes. Of course, this technique has its limits.
2. LENS TREATMENT vs. EYEGLASS LENS COATING:
A lens treatment is a special additive that either bonds with the lens, or is built into the eyeglass lenses themselves during the
lens manufacturing process. A lens coating is exactly what the name implies, an ultra-thin layer of material that is added to the front and/or back surface of a lens.
It’s not uncommon for both lens treatments and lens coatings to be offered individually or bundled into single lens products for convenience and maximum benefit to your eyes.
- Scratch-Resistance: Scratches on lenses are distracting, unsightly and in certain conditions even potentially dangerous.
They can also interfere with the desired performance of your lenses. Scratch-resistant treatments toughen up the lenses making them more durable.
- Anti-reflective Treatments (AR): For fashion, comfort and clarity, anti-reflective treatments are the way to go. They make the lens nearly invisible, and help cut glare from headlights, computer screens and harsh lighting. AR can enhance the performance and appearance of just about any lenses!
- Blue cut lenses: feature a special coating that reflects harmful blue light and restricts it from passing through the lenses of your eyeglasses. Blue light is emitted from computer and mobile screens and long term exposure to this type of light increases the chances of retinal damage.
- Polarized Lenses:
Polarized lenses are usually used to make sunglasses. They are available most commonly in grey or brown tint but many other colors are available. Vertically polarized lenses decrease bright
glare and reflections by blocking horizontal polarized reflected light.
- Photochromatic Lenses:
Photochromatic lenses have a special chemical coating that makes them change to a dark tint in the sunlight and turn clear indoors.
Photochromatic lenses are great for people who do not
wish to carry a separate pair.
A lenses index defines how thick the lens is, the higher the index the thinner the lens. We offer three different lens indexes 1.5, 1.59 & 1.67. As your prescription becomes stronger the lens becomes thicker, therefore stronger prescriptions should be using higher index lenses to reduce their physical thickness.
- Low prescriptions (Up to +/- 4.00)
A 1.5 index lens will be fine, however if you are after a thinner/lighter lens the 1.59 index is a great upgrade.
- Mid range prescriptions (Up to +/- 6.00)
A 1.5 index may become quite thick & therefore we would recommend a 1.59 if you are wanting your glasses to look the part.
- High prescriptions (Over +/- 6.00)
At a minimum we would recommend a 1.59 index however 1.67 would be more suited.
4. TYPES OF OPTICAL LENSES:
- Single vision lenses
Single vision lenses have the same prescription power across the entire lens. Ideal for correcting myopia (near-sightedness) and hyperopia (far-sightedness).
- Toric Lenses
Toric lenses are a type of single-vision lens used to correct astigmatism by adding cylinder correction, an additional prescription power.
- Bifocal lenses
Bifocals are made up of two lenses to correct both near and far-sighted vision. Bifocals have a visible dividing line between the two.
- Trifocal Lenses
Trifocals are made up of three lenses to correct not only near and far distance vision, but also presbyopia, the inability to focus in the middle distance (caused by loss of flexibility in the eye’s lens).
- Progressive lenses
Progressive lenses are becoming an increasingly popular choice over bifocals and trifocals. Progressive lenses correct vision at near,
middle and far distances with no “transition zone” or visible divide.
- Computer glasses: are prescription glasses that are designed to wear when doing computer work. They allow you to focus your eyes on a computer screen, which is farther away than reading material is normally held.
5. SUN PROTECTION:
- Danger of sun: Did you know it’s just as important to protect your eyes from the sun’s harmful rays as it is to shield your skin? The intense ultraviolet (UV) rays of the sun can damage sensitive cells in the eyes, eventually affecting vision. Experts say it is difficult to isolate the exact amount of damage that UV radiation imposes on the eye over a long period.
- Tinted lenses: are lenses with a pigmented dye in them. There are a variety of tint colors available, with the most common being brown or gray. The color doesn’t have an effect on how much protection you’re getting, but is more based on personal preference. Brown offers a warmer hue, giving more of a contrast type of lens, which can distort certain colors.
- Polarized lenses: It has special filters that reduce horizontal reflection of light commonly known as a “glare.” Similar to tinted lenses, there are two main colors used in polarized lenses, brown and gray. Again, just to keep in mind, the color you choose really has no bearing on the protection you get, it’s more of personal preference.