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CONTACT LENSES CONTACT LENSES CONTACT LENSES • Optical devices placed directly in front and adjacent to cornea – To rectify refractive errors – To provide protection – To improve cosmetics 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 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 INDICATIONS OF CONTACT LENSES • Optical indications • • • • • Anisometropia Unilateral aphakia High myopia Astigmatism Keratoconus 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,lid lag,trichiasis) INDICATIONS OF CONTACT LENSES • Preventive indications • Symblepharon , restoration of fornices in chemical burns • Exposure keratitis • Cosmetic indications • Corneal scars • Cosmetic scleral lenses in pthisis bulbi • To change color • Occupational indications • Sportsmen • Pilots 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 • Advantages over spectacles • • • • • Visual fields Optical aberration Accommodation and convergence Prisms Tint CLINICALLY IMPORTANT FEATURES • Field of vision larger field avoid peripheral distortion • Image size CLINICALLY IMPORTANT FEATURES • Accommodation Myopic correction– increased requirement Hypermetropic correction– decreased requirement CONTACT LENS FITTING SCLERAL CONTACT LENSES • Indications Astigmatism(keratoconus,post PKP) Ocular surface disease 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 • Corneal oedema Contact Lens Red Eye with pain & photophobia • Giant papillary conjunctivitis • Corneal neovascularization • Microbial keratitis THANK YOU