Contact lenses

Contact lens, types, and proper usage and maintenance
Video clips included on proper contact lens care!

1. Contact Lenses By Kevin J Ambadan

2. What is a Contact Lens? Artificial device whose front surface substitutes the antr . surface of the cornea Used for correction of: 1. Refractive error 2. Irregularities on front surface of cornea

3. Contact Lens Specifications Diameter 1. Overall diameter (OD ) 2. Optic zone diameter (OZ)

4. Curves Base curve (BC) or central postr . curve (CPC) Peripheral curves 1.intermediate (IPC) 2.peripheral (PPC) Central antr . curve (CAC) or front curve (FC) Peripheral antr . curve (PAC) Intermediate antr . curve (IAC)

5. Edge Union of the Peri.Postr.C & Peri.Antr.C of the lens Power Central anterior curve determines the power of the lens Measured in terms of posterior vertex power in diopters

6. Thickness Measured in the centre of the lens Varies depending upon the postr . vertex power of the lens Tint Color of the lens

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

8. Hard Lens From PMMA ( polymethylmethacrylate ) High optical quality, stability, light weight, nontoxic, durable & cheap Diameter of 8.5-10 mm Disadvantages: 1. restricting the tolerance 2 . corneal abrasions 3 . stable tear film

9. Rigid Gas Permeable Lens Material permeable to oxygen Hard, but called as semisoft lenses Manufactured from: 1. Copolymer of PMMA 2. Silicone containing vinyl monomer 3. Cellulose acetate butyrate

10. Soft Lens HEMA ( hydroxymethymethacrylate ) A bout 1-2 mm larger than corneal diameter Advantages: 1 . comfortable 2 . well tolerated

11. Soft Lens Disadvantages: 1. Wettability 2. Proteinaceous deposits 3. Can get torn 4. L imited life 5. Inferior optical q uality 6. Increased risk of corneal i nfections 7. Cannot correct astigmatism > 2D

12. Soft Lens Types: ▪ Disposable or Non-Disposable ▪ Clear or Colored ▪ Spherical or Toric ▪ Extended Wear ▪ Multifocal

13. Spherical Soft Lens A spherical contact lens is one in which both the inner and outer optical surfaces are portions of a sphere Corrects both short- and long- sightedness Cheapest & most comfortable Easy to get in a disposable form

14. Toric Soft Lens A toric lens is one in which either or both of the optical surfaces have the effect of a cylindrical lens, usually in combination with the effect of a spherical lens Corrects astigmatism Lens is specially weighted to conform to irregular cornea More expensive than spherical Some are available in disposable

15. Disposable Soft Lens Daily, two-weekly or monthly replacement Very simple cleaning (no cleaning for daily) Latest designs and materials Very popular

16. Colored Contact Lens Handling tint Useful when inserting or removing lens Enhancing tint Makes light coloured eyes more vivid Opaque tint Can change colour of eyes

17. Colored Contact Lens

18. Extended Wear Contact Lens New technology Made from silicone material which transmits oxygen well Can wear for up to thirty days without removing

19. MultiFocal Contact Lenses Can have dual focus lenses New technology → More expensive Available as disposable lenses

20. Indications Optical Therapeutic Preventive Diagnostic Operative Cosmetic Occupational

21. Optical Indications Anisometropia Unilateral A phakia High Myopia Keratoconus Irregular Astigmatism

22. Advantage Over Specs Can correct irregular astigmatism Normal field of vision No aberrations Binocular vision in high anisometropia No condensation of rain or fog Cosmetically more acceptable

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

24. Preventive Indications Prevention of symblepharon and restoration of fornices in chemical burns Exposure keratitis T richiasis

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

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

27. Cosmetic Indications Unsightly corneal scars Ptosis Cosmetic scleral lenses in phthisis bulbi

28. Occupational Indications Sportsmen Pilots Actors

29. ContraIndications Mental I ncompetence/Poor Motivation Chronic Dacryocystitis Chronic Blepharitis and Recurrent Styes Chronic Conjunctivitis Dry-Eye Syndrome Corneal Dystrophies and Degenerations Recurrent diseases like Episcleritis , Scleritis & Iridocyclitis

30. Hygeine

31. Complications

32. The End