![]() It is complicated! Eyes are like finger prints -no two are the exact same. emmetropic in one meridian and a prescription in the other).Īll of this is why eye doctors spend so much time in school to really master the art of prescribing glasses. To make things a little more complicated, an eye can have combined prescriptions, meaning it could be a simple myopic eye, a simply hyperopic eye, or a myopic eye with astigmatism, a hyperopic eye with astigmatism, or an eye with only astigmatism ( i.e. The third number (X 180) simply states where the two meridians lie (they can range from 0 to 180). The first number denotes the power needed to correct one meridian while the second number denotes the power needed to correct the other meridian. Therefore, a glasses lens needs to be made to correct for both meridians. Having two different shaped meridians of the eye results in two different points of focus. It is perfect round and equal in all directions.Īn astigmatic cornea looks more like a boiled egg cut in half. Think about a normal cornea looking like a basketball cut in half. Astigmatism occurs when the front surface of the eye (the cornea) is not perfectly round. Since these individuals often see great far away, many individuals actually do not realize that they could benefit from a glasses prescription-even if it is just for reading.Īstigmatism is a whole other topic. Hyperopia is less common than myopia, however it is also more sneaky. To correct hyperopia, eye doctors prescribe plus (+ X.XX ) lenses to bring the point of focus forward to land correctly on the retina. Therefore, light focused slightly behind the retina. Hyperopia occurs when the eye is a little too short. Some of the most common complaints with hyperopes is actually not that they cannot see, but instead that they get headaches after reading or doing computer work, or that their eyes frequently feel tired or fatigued. Hyperopia, on the other hand, occurs when a person can see well far away, but may have a hard time with seeing things up close. In children, you may notice the child having a hard time reading the board at school, holding reading material (cell phones, books, iPads, etc.) abnormally close to their faces, sitting extra close to the TV because they “can’t see”, or even squinting or rubbing their eyes a lot. These individuals can see great up close, but things far away seem blurry. In fact, it is actually thought to be a global epidemic, as more and more of the population is being diagnosed with this problem yearly. Myopia is the most common form of refraction error in today’s society. These minus lens push the point of focus backwards so that it aligns correctly on the retina. ![]() In order to correct for myopia, your eye doctor will prescribed minus lenses (- X.XX ). It occurs when the eye is a little too long, resulting in light focusing in front of the retina. Myopia is more commonly known as near-sightedness. The eye is already perfectly refracting light onto the retina and does not require glasses correction. There are 4 main categories of vision correction- emmetropia, myopia, hyperopia, and astigmatism.Įmmetropia is perfect vision. What are Different Types of Glasses Prescriptions? The main point to understand, is that glasses properly fine tune the refraction of light to allow you to see clearly. There are many, many ways that the eye can be misshapen resulting in defocused vision, however we won’t bore you with the specifics of that here. If the eye is misshapen even a tiny bit (remember we’re talking about microns and millimeters here!) light will not focus perfectly on the macula, and therefore the image perceived by the brain will be a little fuzzy. The eye is the magnifying glass- it’s entire purpose is to focus light right at the retina. If you hold the magnifying glass in just the right spot in front of a piece of paper, the paper will start on fire. Think about a using magnifying glass on a hot summer day. ![]() There are many layers and complex structures within these 22 millimeters to help take incoming parallel light and bend and shape it so it focuses on the retina. The average size of the human eye is 22 millimeters in length from front to back. This may sound simple, but it is actually quite complex! The macula is a part of the retina (the very back structure of the eye responsible for detecting light and transmitting it to the brain) that is responsible for your clearest vision.Īll of the structures of the eye have 1 major job-stay healthy to properly refract light and focus it onto the retina. Glasses are used to correct the eye’s focusing system to allow light to land perfectly centered on a point of the eye called the macula. Whether you are a first time glasses wearer or have been wearing glasses for a long time, understanding your glasses prescription can help you to better understand your eyes. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |