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SlideShare utilise les cookies pour améliorer les fonctionnalités et les performances, et également pour vous montrer des publicités pertinentes. Si vous continuez à naviguer sur ce site, vous acceptez l’utilisation de cookies. Consultez notre Politique de confidentialité et nos Conditions d’utilisation pour en savoir plus.
SOFT TORIC CONTACT LENS
The term is used to describe specially designed soft toric
contact lens that is used to correct astigmatism.
Soft toric contact lens are those lenses having different
power in different meridians.
ACCORDING TO SURFACE:
• FRONT TORIC LENS
• BACK TORIC LENS
• BITORIC LENS
ACCORDING TO LENS MATERIAL
• SILICONE HYDROGEL
ACCORDING TO WEARING SCHEDULE
• DISPOSABLE LENSES
• EXTENDED WEAR LENSES
ACCORING TO COLOURED TORIC
ACCORDING TO SURFACE:
Front surface toric are capable of correcting both corneal and
lenticular astigmatism upto about 4.50 Diopters. They are wide
variety of both corneal and semi-scleral. Stabilization can be
means by prism ballast, truncation or dynamic stabilization. The
back surface may be either spherical or aspherical.
BACK SURFACE TORIC
Back surface toric have envolved logically from the
fact that most of the astigmatism encountered in
practice is predominantly corneal. The back surface of
the lens is essentially designed to neutralize the toric
cornea by replacing it with a spherical front surface.
Cylinder as high as 6.00 Diopters can be corrected
with back surface toric.
Bitoric contact lens are the type of toric soft contact with
two different curves, one curve is on the front surface and
other curve is on the back surface. It is best to utilized
when corneal cylinder is equal to or exceeds 2.50 Diopter.
The two curves allows the saddle principle to provide the
alignment fitting relationship in both meridians.
COLOURED TORIC CONTACT
Toric lenses are suitable for astigmatism patients wanting
to wear coloured contact lenses.
ACCORDING TO LENS MATERIAL
These lenses are made up of hydrophilic ("water-loving") plastics called
This water-loving characteristic, the water content of various
hydrogel contact lenses can range from approximately 38 to 75
Low water content (less than 40 percent water)
Medium water content (50 to 60 percent water)
High water content (more than 60 percent water)
Another feature of hydrogel materials used for soft contact lenses
is their surface charge, which can affect how quickly protein deposits
form on the lenses during wear.
SILICONE HYDROGEL LENSES
Silicon hydrogel is the name of a group of flexible, plastic like
materials that contains silicon, carbon, oxygen and other chemicals.
It is use to increase the oxygen permeability of contact lens.
It enables five times more oxygen to reach to the cornea than
regular hydrogel lenses.
It is also used in the production of RGP lenses to improve oxygen
permeability of the lenses.
SUFFIX: FILCON (E.g: omafilcon, methafilcon, hilafilcon etc ).
• Very high DKs available.
• Suitable for extended
• Rapid adaptation.
• Suitable for patients
• Good dehydration
• Easier handing because
of lens rigidity.
• Low uptake of
• Limited range of complex
designs (toric, bifocals).
• Many available only as
• Greater incidence of
• Frequently exhibit mucin
• More expensive.
It reduces the various conditions like:
rate of eye infections etc.
ACCORSDING TO WEARING
The wearing of contact lenses only during waking
hours, usually daily, weekly, fotirnightly or monthly.
• Reduced risk of allergies
• Eliminate the need for
• Cost saving
• Ideal for children
requiring soft lenses.
• Theoretically better for
most extended wear.
• Spare lenses are also
• Lenses rearly reach the
stage where they build up
• Less time and effort
required with lens
• Increased cost on an
• cost management
• Lenses wear out and must
be replaced in a timely
the use of lenses which are worn continuously ( without
removing) during sleep and waking hours. The waking period
may vary from 24 hours to seven days (usually) or longer.
• Can usually be worn
up to seven days
• Some lenses are FDA-
approved for up to 30
• Available in tints
• Require regular office
visits for follow-up
• Could increase risk of
• Require regular
• Handling may be more
• Vision is unsatisfactory
with a spherical soft
• Astigmatism is 0.75 D
• Tolerance is poor with
• Keratometry and
indicate that a rigid
lens require a much
more complex, bitoric
• Astigmatism is corneal
and rigid lens tolerance
• Existing rigid lens
• Irregular astigmatism.
• Monocular patients.
MANUAL OF CONTACT LENS