CONTACT LENSES

2. CONTACT LENSES

3. CONTACT LENSES

4. CONTACT LENSES • Optical devices placed directly in front and adjacent to cornea • To rectify refractive errors • To provide protection • To improve cosmetics

5. CLASSIFICATION OF CONTACT LENSES • Anatomical position • Scleral contact lenses • Semi-scleral contact lenses • Corneal contact lenses • Nature of material • Rigid non-gas permeable contact lenses(PMMA) • Rigid gas permeable contact lenses(CAB) • Soft contact lenses(HEMA) • Mode of wear • Daily wear contact lenses(hard contact lenses) • Extended wear contact lenses(soft contact lenses) • Disposable contact lenses

6. CLASSIFICATION OF CONTACT LENSES • FDA contact lens classification • Group 1 – Low water content (<50%),nonionic polymers • Group 2- high water content(>50%),nonionic polymers • Group 3- low water content(<50%),ionic polymers • Group 4- high water content(>50%),ionic polymers • Refractive correction • Spherical contact lenses • Toric contact lenses • Bifocal contact lenses(annular,segmental,diffractive,aspheric) • Color • Green • Brown • Blue • Uv blocking • With or without UV blocker

7. INDICATIONS OF CONTACT LENSES • Optical indications • Anisometropia • Unilateral aphakia • High myopia • Astigmatism • Keratoconus

8. Contd • Therapeutic indications(BCLs) • Corneal diseases • Non healing corneal ulcer • Recurrent corneal erosion syndrome(corneal dystrophy) • Bullous keratopathy • Filamentary keratitis • Iris diseases • Aniridia , coloboma , albinism • Other conditions • Post surgery(corneal transplant,LASIK,PRK) • Bell’s palsy • Bleb leak posttrabeculectomy • Lid abnormalities(Entropion,lidlag,trichiasis)

9. INDICATIONS OF CONTACT LENSES • Preventive indications • Symblepharon , restoration of fornices in chemical burns • Exposure keratitis • Cosmetic indications • Corneal scars • Cosmetic scleral lenses in pthisisbulbi • To change color • Occupational indications • Sportsmen • Pilots

10. INDICATIONS (CONTD) • Miscellaneous • Ptosis – haptic contact lens if no Bell’s phenomenon • Occluders – amblyopia in children • Vehicle for drug delivery – soaking a soft contact lens • Protection of normal corneal epithelium in trichiasis or threatened exposure keratopathy

11. Advantages over spectacles • Visual fields • Optical aberration • Accommodation and convergence • Prisms • Tint

12. CLINICALLY IMPORTANT FEATURES • Field of vision larger field avoid peripheral distortion • Image size

13. CLINICALLY IMPORTANT FEATURES • Accommodation Myopic correction– increased requirement Hypermetropic correction– decreased requirement

14. CONTACT LENS FITTING

15. SCLERAL CONTACT LENSES • Indications • Astigmatism(keratoconus,post PKP) • Ocular surface disease

16. COMPLICATIONS 1.Allergic conjunctivitis 2.Giant papillary conjunctivitis 3.Corneal epithelial oedema 4.Peripheral corneal neovascularisation 5.Sterile corneal ulcerations 6.Corneal infection/microbial keratitis 7.Corneal warpage 8.Mechanical or hypoxic keratitis 9.Superficial punctate keratitis/dendritic keratitis

17. Corneal oedema

18. Contact Lens Red Eye with pain & photophobia

19. Giant papillary conjunctivitis

21. Corneal neovascularization

22. Microbial keratitis

23. THANK YOU