Myopia - Optical Correction

• Optical correction contain:
1. Spectacles: Concave lens
2. Contact Lenses

1. Spectacles: 

• Concave lenses are prescribed to correct distance visual acuity.
• In myopia light rays focus in front of retina due to increase in total power of the eye.
• Concave lens divert light rays and help to focused into retina.
• Over myopic power may cause over-corrected Hyperopia and hyperopia related sign-symptoms.

Role of Prescribing concave Lenses:

• Minimum power giving maximum vision should be prescribed.
• Astigamtic power should be fully corrected.
• In high Myopia undercorrection is always better to prevent problem with near vision.

Advantages of spectacles for patients with myopia are: 

1. Economical: 

• Spectacles may be more economical in many cases.

2. Eye safety: 

• Provide some eye safety, particularly when the lenses are of polycarbonate materials.

3. Incorporation with other optical treatments: 

• Spectacles readily allow the incorporation of other optical treatments, e.g., prism, bifocals, or progressive addition lenses.

4. Require less accommodation: 

• Spectacles require less accommodation than contact lenses for myopia, asthenopia or near point blur may be less.

5. Better astigmatism correction: 

• Spectacles provide better correction of some types of astigmatism.

6. Hygiene: 

• Not mandatory like Contact lens

7. Eye Infection: 

• Rare as compare to Contact lens

8. Young Age: 

• More acceptable rate then Contact Lens

9. During Bath: 

• Not problematic like Contact lens

10. One Eyed patient: 

• Provide extra safety

2. Contact Lens:

• Mostly indicated in anisometropia and high refractive error for cosmetic purpose.
• But before prescribing contact lens power need to be stable.
• Mostly used contact lens are:
• Soft Contact Lens
• Rigid Gas Permeable (RGP) Contact Lenses.

Advantages of Contact Lens for patients with myopia are:

1. Cosmesis: 

• Contact lenses provide better cosmesis.

2. Larger retinal image: 

• Contact lenses provide a larger retinal image size and slightly better visual acuity in severe myopia.

3. Less Aniseikonia: 

• Contact lenses result in less aniseikonia in anisometropia.

4. Weight: 

• Less Weight than spectacle

5. Visual field: 

• Provides wider visual Field than spectacle

6. Prismatic Effect: 

• Less Prismatic Effect than spectacle

7.Pantoscopic Tilt: 

• Pantascopic Tilt is absent in Contact lens.

8. Less myopia progression: 

• Reduce the rate of myopia progression due entirely or in part to corneal flattening. 

Conclusion:

• Whether spectacles or contact lenses are preferable in a given case depends:
• Patient age, 
• Motivation for wearing contact lenses, 
• Compliance with contact lens care procedures, 
• Corneal physiology, and 
• Financial considerations.

WATCH IT ON ONLINE: