What eyesight disorders can vision lenses correct?
Article Tags: eyesight disorders, vision lenses
When we are talking about lenses, we mostly refer to the camera lenses and vision lenses, both of which are all optical lenses. Here let’s talk about vision lenses.
Materials of vision lenses
Vision lens was made of crystal at the earlier stage. This kept the vision lens high in price and thus limited ordinary people’s accessibility to vision lenses. Through countless failed experiments, people finally made the vision lens out of the regular glass after cracking down the obstruction of bubble in the glass processing. This triggered the use of vision lenses in a much wider range. Modern material technologies have found that transparent resin is a good substitute for making vision lenses. Later scientists further found that an aviation material called polycarbonate can make much stronger vision lenses that are breakage resistant and lightweight, enhancing the comfort of people wearing vision lens eyeglasses.
Problems correctable by vision lenses
Vision lenses are optical devices with axial symmetry that can be used for transmitting and refracting light. Through converging and diverging light, vision lenses are used for correcting some vision errors occurring in human beings. Correctable refractive disorders that can be solved by vision lenses include nearsightedness, farsightedness and astigmatism. Another condition called presbyopia or aging sight is also correctable by optical lenses. Astigmatism vision is a common yet mild treatable vision imperfection that usually develops together with myopia or hyperopia. Astigmatism vision can be corrected by properly positioning the direction of axis of vision lenses.
The reason for vision lenses’ effectiveness in correcting refractive errors lies in that these problems are commonly linked with an irregular eyeball or lens. A natural, healthy lens is capable of focusing the light entering the eye properly on the retina. However, a myopia or hyperopia eye has an abnormal shape, which can no longer focus the light as needed. Placed before the eyes, vision lenses are just supposed to help focus the light properly, and thus the wearer can see images clearly. Vision lenses that correct presbyopia actually function in a similar way. They also help presbyopic eyes focus things. But the reason for this condition is dramatically different from that for those refractive errors. Presbyopia stems from the natural lens’s gradual thickening and loss of flexibility as people age. This loss in elasticity causes the lens to have a difficulty in focusing close-up objects.
Conditions beyond vision lenses
While some of the vision errors are correctable through the use of vision lenses, more vision disorders can not be fully solved with the help of vision lenses. People above 60 or 70 will probably suffer from eye diseases like cataract and glaucoma causing partial loss or severe permanent deterioration of eyesight. Vision lens can not correct these vision losses, though a special low vision magnifier may help these patients improve their vision.
Eye diseases are generally more complicated than the above vision problems which are under control of vision lenses. Most of them are associated with the eye’s structural damage to different parts. For instance, cataract as a popular eye disease is caused by the clumping and clouding of the eye’s protein. This clouding effect makes it harder to see clearly. In addition, cataracts will develop gradually and become more serious as people age.