Introduction of contact lens

Introduction of contact lens and types advantages /disadvantages

1. MAHANTESH.B HOD OF OPTOMETRY Introduction of contact lens

2. HISTORY OF CONTACT LENS The first physical example of the lens was made by artificial eye-maker F. A. Mueller in 1887. These types of contact lenses were called scleral lenses , 1888, Dr. Fick constructed and fitted the first successful contact lens .

3. What is contact lens ? Contact lenses is a thin lens placed directly on the surface of the eye

4. Why contact lenses ? Contact lenses are considered medical devices and can be worn to correct vision, or for cosmetic or therapeutic reason

5. Advantages of contact lenses Improved all-round vision No glare/light sensitivity Convenient Practical for sportspeople Better suited to people with a high prescription Improved appearance Suitable for all weather conditions Treats certain eye conditions Easy to keep clean No artificial barrier

6. Disadvantages of contact lenses Take time to become accustomed Easily lost Chances of tearing Fiddly to handle Can be more expensive than glasses Require ongoing maintenance Build up of dust and debris Degrade in quality over time Risk of eye infections

7. Indications Optical Therapeutic Preventive Diagnostic Operative Cosmetic Occupational

8. Optical Indications Anisometropia Unilateral Aphakia High Myopia Keratoconus Irregular Astigmatism

9. Therapeutic Indications Diseases of Cornea Diseases of Iris Glaucoma Amblyopia Bandage Soft Contact Lenses

10. Preventive Indications Prevention of symblepharon and Restoration of fornices in chemical burns Exposure keratitis Trichiasis Symblepharon Trichiasis

11. Diagnostic Indications Gonioscopy Electroretinography Examination of fundus in case of irregular corneal astigmatism Fundus photography Goldman’s 3 mirror examination

12. Operative Indications Goniotomy operation for congenital glaucoma Vitrectomy Endocular photocoagulation

13. Cosmetic Indications Unsightly corneal scars Ptosis Cosmetic scleral lenses in phthisis bulbi Unsightly corneal scars Ptosis Phthisis Bulbi

14. Occupational Indications Sportsmen Pilots Actors

15. Contraindication’s Mental Incompetence/Poor Motivation Chronic Dacryocystitis Chronic Blepharitis and Recurrent Styes Chronic Conjunctivitis Dry-Eye Syndrome Corneal Dystrophies Recurrent diseases like Episcleritis Scleritis & Iridocyclitis

16. Types of Contact Lenses Soft Lens Hard Lens Rigid Gas Permeable Lens

17. Soft lenses are made from gel-like, water-containing plastics called hydrogel Silicone hydrogel lenses are an advanced type of soft contact lenses that are more porous than regular hydrogel lenses and allow even more oxygen to reach the cornea silicone hydrogel contact lenses are now the most popular lenses prescribed in the worldwide Soft Lens

18. Hard Lens Hard ( PMMA ) lenses, the original type of contact lens, now virtually obsolete

19. Rigid Gas Permeable Lens Gas permeable contact lenses are rigid lenses made of durable plastic that transmits oxygen. These lenses also are called GP lenses, rigid gas permeable lenses, RGP lenses and oxygen permeable lenses

20. Contact lens parameters Parameter Selection Material Selection Total diameter BOZR ( Base Curve) Centre thickness

21. Material Selection Soft lenses are manufactured from a plastic hydrogel polymer, HydroxyEthylMethacrylate (HEMA) which has a varying water content (38% - ~70%). Lens size is between 13.00 and 14.50mm. Centre thickness from ~30um. Hard contact lenses are manufactured from a rigid material, PolyMethylMethacrylate (PMMA). This material can be combined with other plastics to increase the oxygen permeability. Lens size is between 8.0mm and 10.00mm. Centre thickness from ~100um.

22. Total diameter BOZR ( Base Curve) Measure HVID (Horizontal Visible Iris Diameter)Add 2mm to HVID Select trial lens set with nearest diameter Base Curve Selection Measure Ks (mm) then add either: • 0.8 mm to flattest K 4 D flatter than average K Select lens of nearest Base Curve from trial set