Transcript Introduction to Contact Lenses

Introduction to Contact Lenses
Objectives
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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 History
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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 ?
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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:
• 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
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Soft Contact lens - allows good oxygen
transmission. Highly comfortable. Easy to fit.
Conventional Soft Lens Materials
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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 Materials
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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 Materials
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Silicone and hydrogel are combined to create
a revolutionary soft contact lens material
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Exceptional oxygen permeability
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Excellent on-eye performance and comfort
Wear Modality
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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 Schedule
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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
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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)
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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:
• Wider field of view (Improved Peripheral
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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:
• 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
Wear
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Myopia
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Hyperopia
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Astigmatism
Presbyopia
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Aphakia
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Keratoconus
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Astigmatism secondary
to post-op/trauma
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Corneal protection
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Corneal healing
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Occupational
requirements
Contraindications for Lens Wear
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Anterior segment
inflammation or
infection
Chronic ocular allergy
Certain systemic
diseases
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Ptosis
Corneal hyposensitivity
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Chronic dry eye
Poor quality or
inadequate tearfilm
Occupational
incompatibility
Noncompliant,
unmotivated patient
Poor patient hygiene
Contact Lens Design
and Application
Single Vision Spherical Soft
Contact Lenses
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Myopia
Hyperopia
Presbyopia
Aphakia
Most widely prescribed
contact lenses
Toric Soft Contact Lenses
Presbyopic Soft Contact Lens
Correction
Cosmetic Tinted
Soft Contact Lenses
Therapeutic and Bandage
Lenses
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Promote corneal healing
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Treat corneal/ocular disease
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Collagen lenses offer good results
Lens Care Systems
• Deposits composed of protein, lipids,
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mucin and other organic and inorganic
substances need to be removed
Cleaning
 Surfactant – to remove surface deposits
 Enzymatic – to remove protein deposits
Lens Care Systems
• Rinsing
• Disinfection
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 Chemical
disinfection
 Thermal disinfection
 Hydrogen peroxide
Storage
Lens Lubricants
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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
For Further Queries Contact :
Ms. Priyanka Singh
Head – Optometry Service
Email – [email protected]
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