CONTACT LENS
INSERTION PROCEDURE
Preparation of the patient - Use topical
local anaesthetic only. Sedation may be required; however,
third eyelid prolapse is a disadvantage. Excessive topical
local may slow the blink rate causing dehydration of the contact
lens (extra lubrication may be required initially if this is the
case).
Measurement of the cornea and lens size -
Callipers are used to measure the cornea from limbus to
limbus. Use the nearest (but smaller) lens size to the actual
diameter of the cornea.
Preparation of the cornea - Ensure no hair or
debris remains on the cornea. Remove undermined edges of
epithelium from around the ulceration (extreme care is required in
cats). A drop of extra-ocular visco-elastic (Keralon)
provides a good liquid base for the lens to sit on
(optional).
Preparations of the contact lens - Remove the
lens from its container using a cotton-tipped applicator and make
sure it is inverted the correct way (Taco test - see TIPS
below).
Insertion of the lens - Place the lens onto the
cornea either with fingers or with using the same cotton-tipped
applicator. Take care to remove any air bubbles and ensure
that the lens is under the leading edge of the third eyelid using
the cotton-tipped applicator.
Tips:
The Taco Test - Squeeze the two edges of
the lens together and it should form a 'taco' shape when correctly
orientated. If the lens resists this movement and curls onto the
fingers then it is "inside-out". The tapered edge of the lens
angles out like a saucer if the lens is "inside out". As the
lens is removed from its container by a cotton-tipped applicator,
when it is correctly orientated, the lens wraps around the
applicator and then unfurls when the free overhanging edge of the
lens is "smoothed" onto the cornea.
Use only drops not ointments - Ointments or oil
based drops (e.g. Cyclosporin) clogs the oxygen transference of the
lens and must not be used.
Keep the lens wet - The lenses are hydrophilic
(i.e. water loving) and they cannot be used in cases of inadequate
tear film.
Check at least weekly - Weekly examination of
patients with contact lenses is recommended, with cleaning and
replacement of the lens if necessary.
Problems:
For lenses that keep falling out - Use a
different size lens and/or different curvature - there are three
sizes denoting curvature for each available lens diameter. A
Partial Tarsorraphy assists with retention of the lens in some
animals.
For lenses that dehydrate - Rehydrate the
lens by soaking it in distilled or de-mineralised water (D-water)
and as long as the lens is not torn or damaged in any way then it
can be re-used after autoclaving.
Autoclaving:
Lenses should be autoclaved if they become contaminated. Return
the lens to its original container after cleaning with D-water and
fill the container with D-water. Remove the seal from inside the
lid and screw on very loosely. Place autoclave indicator tape
on the bottle then autoclave using the setting where
depressurization is graduated over time allowing D-water not to be
boiled and therefore evaporate off.
Address
CHAMPION LAKE VET CENTRE
121 Westfield Road
(corner Ypres Road)
Camillo, 6111
West Australia
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Contact Us
Ph: (08) 9390 7622
E: admin@championlakevet.com.au
Opening Hours
Monday to Friday – 8am to 7pm
Saturday – 8am to 2pm
For After-hours Emergencies call 9390 7622