What is a Refractive Error?

A Refractive Error is a condition in which a clear image fails to focus on the retina due to optical reasons within the Eye. This could be due to Cornea, Lens or Length of the Eyeball

What are the different types of Refractive Errors?
  • Myopia or short-sightedness is the condition when due to large size of the eyeball the light is focussed in front of the retina. The person is unable to see distant objects clearly.
  • Hypermetropia or far-sightedness is the condition when due to small size of the Eyeball, the light rays get focussed behind the retina. The person is unable to see near objects clearly without strain.
  • Astigmatism or cylindrical error is the condition when due to irregular curvature of the cornea, a point focus of light is not formed at the retina. All the objects appear blurred to such people. It can be of simple, compound and mixed type depending on where and how the image is formed in relation to retina.
What is the cause for Refractive Errors?

Refractive Errors are thought to occur due to a combination of genetic and environmental factors. Trauma or ocular disorders such as keratoconus may induce Refractive Errors.

How can Refractive Errors be overcome?

Refractive Errors can be overcome by either using temporary aids like glasses and Contact Lenses or permanently by undergoing a Refractive Surgical Procedure-Lasik.

Tell me something about Frames and Lens of Spectacles?

Eyeglass frames are commonly made from metal or plastic. Lenses were originally made from glass, but many are now made from various types of plastic, including CR-39 or polycarbonate. These materials reduce the danger of breakage and weigh less than glass lenses.

  • High index lens-Some plastics have a greater index of refraction than most types of glass, this is useful in the making of Corrective Lenses shaped to correct various vision abnormalities such as myopia, allowing thinner lenses for a given prescription.
  • Anti-reflective coatings intended to improve night vision and make the wearer's Eyes more visible.
  • Polycarbonate lenses are the lightest and most shatter-resistant, making them the best for impact protection, yet offer poor optics due to high dispersion.
  • CR-39 lenses are the most common Plastic Lenses due to their low weight, high scratch resistance, and low transparency for ultra violet and infrared radiation.
What are Contact Lenses?

These are small Plastic Lenses fitted to the size and shape of patient's cornea, floating over the tear film layer.

Why are Contact Lens used?

These are used to Correct Refractive Errors like Nearsightedness, Farsightedness & Corneal Astigmatism. Special Lenses are available for keratoconus. Also therapeutic Contact Lens are used for various Eye Diseases. Some people also use colored Contact Lenses for Cosmetic purpose.

How are Contacts fitted?

After thorough examination of your Eye, the best lens for an individual's Eye is advised. Various type of lenses include rigid (hard), rigid gas permeable(semisoft), soft, toric, extended wear & disposable lenses. A series or trial lenses may also be used in determining the best size and fit, before your custom made lenses are ordered.

Are Contact Lens Safe?

Yes, they are. One has to be careful with the handling and care of the lens.

At what age can one start using Contact Lens?

They can be used at any age but should be able to take care of the lens. Usually we expect children in teens to be mature enough to handle the lens well.

I have Refractive Error, what should I opt for-spectacles, Contact Lens or Lasik?

The option of any of above depends on the age, Refractive Error ,Eye Condition and Personal Choice.

  • Age- Contact Lens and Lasik is not an option for children. They should wear spectacles. Teenagers can use Contact Lens while the minimum age limit for Lasik is 20 years.
  • Contact lens is a safe option if a person does not want to wear glasses.
  • If Contact Lens do not suit you or find it cumbersome to handle them, Lasik is a good option .It gives you a permanent solution to get rid of your Glasses or Contact Lens. Only the reading or near number may come up later in life after 40 to 45 yrs of age. There are certain parameters in Eye which need to be examined upon prior to opting for Lasik eg- Corneal Thickness, tear film, retina etc. The Ophthalmologist will examine your Eyes in detail and guide you accordingly.