Download - Introduction to Contact Lenses
Introduction to Contact LensesIntroduction to Contact Lenses
ObjectivesObjectives
• Describe evolution of contact lenses
• Describe types of contact lenses
• Identify basic parameters of contact lenses
• Identify uses and benefits
• Describe fitting procedures and care regimens
Contemporary HistoryContemporary History
• Four significant milestones: 1940s – development of PMMA (hard lenses) 1970s – development of HEMA (“hydrogels” or
soft lenses) 1980s – development of rigid gas permeable
(RGP) lenses 1999 – development of silicone hydrogel lenses
What is a Contact lens ?What is a Contact lens ?
• Contact lens is an Optical device or lens which is used to correct Refractive errors,
change color of the eye or for therapeutic purposes
Types of Contact Lens:Types of Contact Lens:
• Hard Contact lens - Obsolete as does not allow Oxygen to pass through
• Rigid Gas Permeable lens (semi-soft lens)- allows better oxygen transmission.Poor comfort. Cumbersome fitting procedure
• Soft Contact lens - allows good oxygen transmission. Highly comfortable. Easy to fit.
Conventional Soft Lens MaterialsConventional Soft Lens Materials
• HEMA ( Hydroxy Ethyl Methacrylate) is the most common material for conventional lenses
• FDA has divided SCL materials into 4 groups on the basis of water content & Ionicity
• Group1- LWC,Non-Ionic
• Group2 –HWC,Non-Ionic
• Group 3- LWC, Ionic
• Group 4 –HWC, Ionic
RGP Lens MaterialsRGP Lens Materials
• RGP lenses combine standard PMMA with silicone
• PMMA is a clear plastic material that is impermeable to oxygen
• Offer excellent vision
• Easy to handle, durable
• Simple to care for
Silicone Hydrogel Lens MaterialsSilicone Hydrogel Lens Materials
• Silicone and hydrogel are combined to create a revolutionary soft contact lens material
• Exceptional oxygen permeability
• Excellent on-eye performance and comfort
Wear ModalityWear Modality
• Wear modality refers to how the contact lens if worn by the patient.
• Wear modality is divided into two groups: Daily wear Extended wear Continuous wear
Replacement ScheduleReplacement Schedule
• Replacement schedule refers to how often contact lenses are replaced
• Lenses are generally replaced on a “traditional schedule” or a planned replacement/disposable schedule
“Traditional” Contact Lens Wear“Traditional” Contact Lens Wear
• Patients once wore same pair of lenses until they experienced discomfort, or lens was lost or torn.Average life of a traditional lens is 1 year.
• Today, “traditional lens replacement” has been replaced with Planned Replacement/ Disposable schedules
Planned Replacement/ Disposable (PRD)Planned Replacement/ Disposable (PRD)
• Contact lenses are replaced more frequently (one to three months)
• Disposables are discarded at end of wear and never reused
• Disposable may be worn daily or extended wear basis
Advantages of Contact lens over Spectacles:Advantages of Contact lens over Spectacles:• Wider field of view (Improved Peripheral
Vision)
• Active lifestyle
• No tell tale marks , no sliding down the nose
• No fogging wih sudden temperature changes
• Natural Good Looks
Advantages of Contact lens over Spectacles:Advantages of Contact lens over Spectacles:• Better clarity of Vision
• Actual size of object is seen unlike in high power spectacles
• IMMENSE SELF-CONFIDENCE
See Better, Look Better, Feel Better
Indications for Contact Lens WearIndications for Contact Lens Wear
• Myopia
• Hyperopia
• Astigmatism
• Presbyopia
• Aphakia
• Keratoconus
• Astigmatism secondary to post-op/trauma
• Corneal protection
• Corneal healing
• Occupational requirements
Contraindications for Lens WearContraindications for Lens Wear
• Anterior segment inflammation or infection
• Chronic ocular allergy
• Certain systemic diseases
• Ptosis
• Corneal hyposensitivity
• Chronic dry eye
• Poor quality or inadequate tearfilm
• Occupational incompatibility
• Noncompliant, unmotivated patient
• Poor patient hygiene
Contact Lens Designand Application
Contact Lens Designand Application
Single Vision Spherical Soft Contact LensesSingle Vision Spherical Soft Contact Lenses
• Myopia
• Hyperopia
• Presbyopia
• Aphakia
• Most widely prescribed contact lenses
Toric Soft Contact LensesToric Soft Contact Lenses
Presbyopic Soft Contact Lens Correction
Presbyopic Soft Contact Lens Correction
Cosmetic Tinted Soft Contact Lenses
Cosmetic Tinted Soft Contact Lenses
Therapeutic and Bandage LensesTherapeutic and Bandage Lenses
• Promote corneal healing
• Treat corneal/ocular disease
• Collagen lenses offer good results
Lens Care SystemsLens Care Systems
• Deposits composed of protein, lipids, mucin and other organic and inorganic substances need to be removed
• Cleaning Surfactant – to remove surface deposits Enzymatic – to remove protein deposits
Lens Care SystemsLens Care Systems
• Rinsing
• Disinfection Chemical
disinfection Thermal disinfection Hydrogen peroxide
• Storage
Lens LubricantsLens Lubricants
• Lens lubricants are used when lenses become dry and uncomfortable
• Extended-wear lens patients are encouraged to use lubricants prior to sleep and upon waking
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