Contact lens – Basic Overview


by Jimi Sherpa

Contact lenses are medical devices which are mainly used for correcting refractive error. Apart from that, they are also used for therapeutic, cosmetic and various other purposes. Their first documented use occurred in the 1880s. They are placed directly on the eye.  The posterior part of the contact lens comes in direct contact with the anterior surface of the cornea.

Contact lenses are of various types but mainly they are classified into three types viz SCL (Soft Contact Lens), RGP CL (Rigid Gas Permeable Contact Lens). SCL is mainly used for correcting myopia (short-sightedness), hyperopia (long-sightedness) and astigmatism only to some extent. The main advantage of the soft contact lens is their shorter period of adaptation and high level of comfort. They are available with many parameters so that all regular refractive errors are covered. Multifocal SCL is also available for correcting Presbyopia and used instead of bifocal glasses. RGP CL is mainly used for correcting high astigmatism and irregular astigmatism in cases like Keratoconus. The main advantage of RGP lens is the quality of vision they offer and the ease with which they correct astigmatism. For advanced cases of Keratoconus, various other specialized CL like piggyback CL, Hybrid Scleral CL and Rose K CL are also available. Multifocal SCL is also available for correcting Presbyopia and used instead of bifocal glasses.  Therapeutic Contact lens or Bandage Contact Lens (BCL) is specially used for healing purpose. It is used to enhance epithelial healing, prevent epithelial erosions, or control surface-generated pain; they are not used for their optical properties. It is used in case of Bullous keratopathy, Recurrent erosions, filamentary keratitis and post-surgery (LASIK, photorefractive keratectomy). A special type of contact lens called a prosthetic contact lens is used for better cosmetic. Coloured contact lenses are also used for cosmetic purpose. Scleral CL is used in cases of the severe dry eye like Steven Johnson syndrome. Ortho- K contact lens is also a special type of contact lens. It is mostly used to reduce high myopia by reshaping the cornea and it’s reversible. The lens is worn only during sleep and provides good vision at night, if needed and good vision all day without correction.

Despite of its various use, Contact lens users are quite less in Nepal compared to other countries. It has a better advantage over spectacle in different ways especially for the sportsman, (except swimmer), dancers, celebrities and many more.  In cases of Anisometropia (difference in refractive error between two eyes), it plays a great role. Contact lens gives a wider visual field compared to the spectacle. In case of very high refractive error, spectacle user bears peripheral aberration, magnification and magnification of images whereas these problems are absent in contact lens users. Spectacle users must be made aware of the various options of the contact lens by the eye specialists in the hospital or clinic itself. Almost most of the contact lenses are available in Nepal. Very rarely contact lens needs to be ordered from abroad like Scleral CL or Ortho-k CL. In Nepal, people are yet to be aware of the various types of CL available and their utmost importance especially in high refractive error and various ocular conditions.

Prescribing contact lens is not a very big deal if done with proper counselling. Along with instruction of how to use it, contact lens users must also be well aware of its contraindications. Though there are only a few of them, these are very crucial for maintaining eye hygiene and especially to prevent eye hazards. Contact lens users are taught well about the proper lens insertion and removal techniques, a wear schedule is determined depending on its type to know when the lens should be disposed of or replaced. Most contact lenses are removed after use, cleaned, stored, and used again (l-day disposable lenses are the exception). Multipurpose solutions are available for cleaning and storing contact lens, Some of the important guidelines to be followed are:-

  • Always wash hands, before handling contact lenses.
  • Clean and disinfect a lens whenever it is removed.
  • Do not use tap water for storing or cleaning lenses because it is not sterile.
  • Do not use homemade salt solutions, which also are not sterile.
  • Do not allow the dropper tip of the solution to touch any surface; close the bottle tightly when not in use.
  • Clean the contact lens case daily and replace it every 2-3 months; the case can be a source of contaminants.
  • Do not use contact lens while sleeping, swimming and bathing unless recommended
  • Carry a spare pair of spectacle to use whenever the contact lens falls off.
  • Carry a lens case filled with a solution with you while going out of the house.
  • Wear goggles when moving out in a dusty environment.
  • Follow instructions regarding cosmetics usage with contact lenses.
  • Lenses unused for a long time should be disinfected always before reuse.
  • Cracked or chipped lens should never be worn.
  • Do not rub your eyes vigorously with the lens on the eye.

Being well aware of these simple guidelines will help the user to maintain good eye hygiene and better vision.

Leave a Reply

Your email address will not be published. Required fields are marked *