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

• 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

INDICATIONS (CONTD)

• 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

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

COMPLICATIONS

• Corneal oedema

Contact Lens Red Eye with pain & photophobia

• Giant papillary conjunctivitis

• Corneal neovascularization

• Microbial keratitis

THANK YOU