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1. STABILIZATION PROCEDURE FOR REDUCE
THE ROTATION OF CONTACT LENCE
Name :Sarjina Begum, Badaribha Khapran, Injamamul Hoque,
Sushma Wangkem, Amir Hamza
Enrollment ID : ADTU/2021-25/BOP/007/012/025/087
ADTU/L/2021-25/BOP/092
Program : Bachelor of optometry
Cource : Contact lens II
Faculty : Rakibul hassan khan

2. INTRODUCTION
• More than 1/4 of all contact lens patients have astigmatism more
than 1.25D. Stabilization technique is a very important procedure to
stable the high toric contact lens on the toric cornea. Because in case
of high astigmatism, there is a variation of contact lens thickness at
different region of the contact lens and due to this reason there are
chances of expelled of contact lens from the cornea.
TORIC CONTACT LENS
There are two types of toric contact lenses are used.
• Soft toric contact lens - Most commonly used toric contact lenses
• RGP toric contact lenses

3. Surface design of soft toric CL
It is 3 types
1. Front surface toric
2. Back surface toric
3. Bi-toric

4. STABILIZATION
• Better vision needs stable cylinder axis in proper place
• Lid movement will attempt to move the lens in the
same direction as itself.
• Gravity and the inertia of lens and tear fluid, play
relatively insignificant roles.
There are 4 types of stabilization are used.
1. Prism ballast
2. Truncation
3.Double slabe off
4. Reference marking of CL

5. Prism ballast
• A base down prism of between 1.00 to 1.50 D is
ground at the lower part of the lens ,so that the
lens will be heavier at the prism base. Gravity
then acts to cause the
• However , greater amounts of prism may be
needed for patients with particularly tight lids,
flat corneas , or oblique axis astigmatism .
• The lens will tend to rotate so that the base of
the prism is oriented inferiorly .
• The added thickness of the lens along the prism
base can reduce oxygen permeability through
that portion of the lens resulting in possible
hypoxic disturbance in the inferior zone of the
cornea.prism base to locate inferiorly.

6. Truncation
• Truncation refers to the techniques of
cut off the bottom of the lens , so as to
form a ‘shelf’ that will rest upon – and
therefore align with – the lower lid.
• This is a reasonably successful method
of stabilizing lenses with thick edges,
especially when combined with prism
ballast. Either a single lower truncation
, or a double truncation can be used.
• The truncated section of the lens that is
removed can be anywhere between a
sag of 0.5 and 1.5 mm.

7. Double slab off
• In this technique two thin zones are created
superiorly and inferiorly.
• These designs also rely on the interaction between
lids and the lens to achieve stabilisation.
• Both eyelids play an active role, unlike prism-ballast
designs that involve interaction primarily from the
upper lid. The design utilises thin zones; the lids
squeeze against the thickness differential across the
lens aligning the thicker central portion within the
palpebral aperture and the thinner zones under the
eyelids (figure 2a).
• Refinement of this stabilisation approach has led to
designs that isolate the optical correction within an
optic zone resulting in independent stabilisation
areas.

8. Reference marking
• Soft toric lenses will usually have markings on the lens at a
specific reference point so the degree of rotation can be
assessed when the lens is on the eye.
• Different manufacturers have different markings.
• • They have may be usually permanent a laser or a temporary
one with an ink or dye.
• These markings indicate the lens orientation, helping both the
wearer and the eye care professional to position
the lens correctly.
• • They are either a single or 3 marks with specific separation
angle at the 6 o’ clock or horizontal (3 and 9 o’ clock) axis.
• • One must refer to manufacturer’s guidelines before
estimating rotation. Lens markings are for reference only.