Refractive Errors of the Eye & Available Optical Divices / Treatments

                            Spectacles / Eye Glasses

Spectacle lenses are the most easier way to treat the Refractive Errors. 

Barthhold Laufer- German-American anthropologist stated that the opinion of spectacle is originated from India. And probably since 54 A.D. we started to use spectacle.

Initially these lenses were Convex Lenses and were able to fulfill the visual requirement in Presbyopia and Farsightedness.

But gradually technical advancement had made the Spectacle lenses very efficient in correcting  all types of refractive errors.

Treatment of Farsightedness:
                        As we know already Farsightedness or Hyperopia is a result of in sufficient  convergence of light than the requirement Considering the eyes Axial length.

So its clear that in this case we need more convergence or Converging lens or Convex Lens.

Generally Prescription will be ,-

Nearsightedness:

                         Nearsightedness or Myopia is a result of  excessive convergence of light than the requirement, Considering the eyes Axial length.

So its clear that in this case we need less convergence or Divergence or Diverging lens or Concave Lens.

Generally Prescription will be ,-

                         

 Astigmatism:
                           When we think about the Diagram of Astigmatism we can make out that some of the light rays are creating focus before retina and some of the light rays creating focus after retina.

So we need Convergence at the same time Divergence through a single lens.

Generally Prescription will be ,-

 Except Spectacle other choices also we have like,-

Contact Lenses, Refractive Surgery & Orthokeratology.