Transcript contact-lenses

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
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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
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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
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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
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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
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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