This section will hopefully give you a better understanding of how refractive problems with your vision can be corrected. If you have any questions about these concepts, please do not hesitate to ask me during your consultation.
What are refractive vision problems?
A person can be myopic (near-sighted or short-sighted), hyperopic (far-sighted), or have astigmatism, due to an irregular shape in the cornea or natural lens. Myopia, hyperopia, and astigmatism all cause an image to be out of focus on the retina. If the image is out of focus on the retina, then a blurry image is perceived by the brain. In myopia the image is formed in front of the retina, while in hyperopia the image is formed behind the retina. Astigmatism can cause the image to be formed in front or behind the retina. Vision correction brings the image back in focus where it belongs, clearly on the retina.
A person can also be presbyopic, or have lost their ability to focus on near objects. This generally occurs when we are in our forties and continues to progress with age.
What is vision correction?
Vision correction refers to bringing an object in the distance, that you are looking at, into clear focus onto your retina. Images that are located on the retina can be seen clearly, while those formed in front or behind the retina are seen as blurry. Vision correction can be accomplished using spectacles, contact lenses, changing the shape of the cornea (laser vision correction), replacing the natural lens of the eye with an intraocular lens (refractive lens exchange), or adding an intraocular lens into an eye with the natural lens remaining in place (phakic intraocular lens).
It is important to understand the difference between distance objects and near objects. Distance objects are those things we look at greater that an arms length away. Being able to see near objects, or those things within an arms length, brings up a whole new set of issues.
What refractive vision problems are correctable?
Myopia, hyperopia, and astigmatism are all correctable up to certain limits. If you have myopia, hyperopia, or astigmatism and you would prefer to avoid using spectacles or contact lenses, then there are a few options available to correct these. Basically, it is possible to change the shape of the cornea using a laser, exchange the natural lens of the eye for an appropriately powered intraocular lens, or an intraocular lens can be inserted while keeping the natural lens of the eye. Please see the refractive surgery section for a further discussion on these options.
Presbyopia is not easily corrected. There are several refractive options that allow for both distance and near vision to be corrected. However, none of these options provide as good quality vision as the natural lens did prior to the onset of presbyopia. Some of these options include bifocal spectacles, multifocal contact lenses, and monovision contact lenses. Refractive surgery options include multifocal intraocular lenses, accommodating intraocular lenses, monovision intraocular lenses, and several others. During your vision evaluation and consultation, we can discuss the risks, benefits, drawbacks, and alternatives to each of these options.