In order to resolve and to correct the different eye problems, most of people will go to the eye doctor or ophthalmologist to have their eyes checked and probably to get the Eye glasses stores Ottawa prescription to correct their eyesight. Here are the four common types of prescription lenses: Four Types of Prescription Lenses There are four types of refractive lenses that are commonly used to correct refractive eye errors. These eyeglass lenses are apt for the different types of refractive eye errors such as myopia, hyperopia, presbyopia and astigmatism.
* Unifocal prescription lenses- This type of eyeglass lens have one or single focal point. Under this type of prescription lens are the spherical, cylindrical and aspherical prescription lenses. Unifocal prescription lenses may provide solutions for myopia and hyperopia.
* Bifocal prescription lenses- Bifocal eyeglass lenses have two focal points. They usually have another or additional lens that is connected to the one-focal point lens. The basic part is used for looking at long distance, while the other is used for looking at short distance. The one focal point may either be sealed or cut from the basic part. This particular prescription lens is commonly recommended for people with presbyopia who also need correction for other refractive errors such as myopia, hyperopia and astigmatism.
* Trifocal prescription lenses- This particular type of eyeglasses has three focal points and has an inserted middle piece for looking at the middle distance. Similar to bifocal prescription lenses, trifocal are also used in restoring clear eyesight for presbyopics.
* Multifocal prescription lenses- This is also referred to as progressive lenses that have a sharp vision in all distances. Presbyopia, which is a condition brought by aging, is commonly corrected by multifocal prescription lenses. It also has the ability to correct other eye and vision problems.
Snellen Eye Chart and Visual Acuity To determine on what kind of glasses will suit the person who need it, a person need to have a standard eye chart, which is widely used to compare and record people’s visual acuity. The Snellen eye chart by Dr. Hermann Snellen is the most commonly used. Dr. Snellen discovered the relationship between the sizes of objects seen at certain distances. The eye chart is made to measure the visual acuity of the eye but not detect the most common eyesight problems like hyperopia and myopia. When a person is experiencing eye and vision problems, it has become imperative that he or she wear prescription glasses. Most Common Refractive Errors
* Hyperopia (Farsightedness)
The hyperopia is the condition of being farsighted. Its causes are usually genetic which involve an eye that is too short or a cornea that is too flat, so that images concentrate behind the retina. Those who suffer from hyperopia can usually see distant objects clearly but have trouble focusing on nearby objects. A child has a possibility of having hyperopia if it is present in the family. It can be detected by an ophthalmologist with a comprehensive eye exam. The ophthalmologist will be able to not only detect problems but he can also determine the degree and ideal treatments as well because a simple visual acuity test will usually not be adequate to detect hyperopia. Those who have mild hyperopia do not require corrective lenses or any type of treatment while people who are severely farsighted have a variety of treatment options offered to them, one of which is to wear prescription glasses.
* Myopia (Nearsightedness)
Myopia or nearsightedness, on the other hand, happens when a person see unclear image of something unless it is very close. Special skills and materials are used in making eyeglasses for myopia. The frames must be a perfect fit to the eye. To provide high prescriptions, small lenses are used for myopic eyeglasses. To correct the different type of refractive errors such as myopia and hyperopia, one of common options is to buy and wear eyeglasses or contact lenses.