CATARACT

WHAT IS A CATARACT?

The lens is a unique living ocular tissue that is usually clear or transparent
and is referred to as 'the crystalline lens' by doctors. The normal lens
focuses light on the light-sensitive nervous tissue located in the back of the
eye which is known as the retina. A cataract is an opacity (or cloudy change)
of the lens that scatters light and looks gray or white. The word cataract
literally means "to break down." The word applies to waterfalls and rapids
as well as to the lens. Cataractous changes of the lens may appear as small
insignificant dots, microscopic blisters, a cracked-glass appearance, a
diffuse haze, a "pearl-like" sheen, white streaks or a completely white lens.
The cataract usually starts as small dots or microscopic blisters and
progresses to involve larger areas of the lens. The rate of progression is
difficult to predict and may be very slow or quite rapid. At times the
cataract appears to worsen overnight. Cataracts may develop in one or in
both eyes. If a large portion of the lens becomes white, it prevents formed
images from reaching the retina and blurred vision results. When a light is
shined into the eye of a patient with a complete cataract, the patient only
sees a white light and no images can be seen. 

WHAT SHOULD YOU DO IF A CATARACT IS SUSPECTED?
 

The first thing to do if your veterinarian indicates your pet has a cataract
is to have your pet examined by a veterinary ophthalmologist. The lens is an
important link of the total visual system, yet the health of the entire eye
should be evaluated before the lens develops a complete cataract. Early
evaluation of the eye with a cataract sometimes permits examination of the
retina. If the cataract is complete and 'mature', the retina cannot be
directly examined and an ultrasound or an electroretinogram examinations,
or both may be needed to assess the health of the retina. At the time of the
initial examination, the cataract may sometimes be identified as to cause,
area of involvement and stage of progression. Not all cataracts lead to
blindness. "Incomplete" cataracts may not impair vision significantly. If
your pet has a cataract and has shown some visual loss, evaluation will
include the consideration of and benefit of cataract surgery. 

HOW DO YOU KNOW IF YOUR PET HAS A VISION PROBLEM?
 

Animals are creatures of habit and pets love to please their owners. If
vision loss develops slowly over a long period of time, your pet may adjust to
your home and yard. Pets in familiar surroundings may readily move about
even when almost blind because they have learned where all objects are.
Signs such as bumping into objects, failing to retrieve favorite toys and fear
of being left alone may be signs of vision loss. These are especially
significant if they occur within the pet's home or yard. 

WHAT CAUSES CATARACTS?
 

The cause of cataracts is an area continually being studied. Cataracts may
result from injuries to the eye, inflammation within the eye (uveitis), internal
diseases that have an effect on the eye such as diabetes mellitus and some
cataracts are inherited. Although it may be difficult to name the specific
cause of a cataract, cataracts that develop in eyes free of signs of ocular
disease are assumed to be inherited. Inheritance is the major cause of
cataracts in dogs and cats. 

ARE THERE TYPES OF CATARACTS?

The type of cataract may not be important for deciding whether surgery
may be performed. Cataracts may be classified by age of onset (congenital,
acquired or juvenile, or senile), physical appearance of the cataract (location
in the lens -see below), state of development of the cataract (incipient,
immature, mature, hypermature or morgagnian), or cause (traumatic,
diabetic, inherited). 

WHAT IS THE TREATMENT FOR CATARACTS?

There is no medical treatment known to slow the progression of, prevent the
formation of or reverse the changes of cataracts. Surgery to remove the
cataractous lens is the only known treatment in animals and man. Successful
surgery can provide a return of vision. 

SHOULD MY PET HAVE CATARACT SURGERY?

Cataract surgery is generally restricted to those patients who have
developed a cataract in both eyes. If one eye has a blinding cataract and the
other eye has a rapidly developing cataract or if rapidly developing
cataracts are present in both eyes, surgery is recommended so the patient
will not completely lose vision. It is also important to consider whether the
patient is a good candidate for anesthesia. With continued improvements in
veterinary medicine and anesthesia, age alone does not a limit the possibility
of surgery. With the use of modern anesthetic agents, successful surgery is
performed on dogs and cats 17-18 years of age and older. The over-all
health of the patient needs to be assessed before surgery. This may include
chest x-rays, EKGs, blood chemistry or other procedures as recommended by
your veterinarian. Cataracts may be removed from one or both eyes during
the same surgery. Finally, you are the one who hears all the information and
decides if surgery will be performed to restore vision for your pet. 

IS MY PET A GOOD CANDIDATE FOR CATARACT SURGERY?
 

Cataract surgery involves a period of intense pre- and post-operative care
followed by an extended period of low level therapy. If you are unable to
provide this treatment, surgery is not recommended. Alternatively, if your
pet will not or cannot be treated as required, he/she is not a good surgical
candidate. Animals who bite the hand that feeds it don't do well after surgery. 

WHAT WILL MY PET BE ABLE TO SEE AFTER SURGERY?
 

Patients benefit from cataract surgery because it will allow them to be able
to move about without the fear of bumping into objects. As in people, the
loss of the lens causes a loss of up-close visual acuity or sharpness. Without
a lens, a pet may not have completely normal vision after surgery, but they
do regain some vision. The image they see will be slightly larger and only
partially focused so that the images will be much less distinct. Although our
pets don't drive, play golf or tennis they need sharp vision yet it is not as
necessary as for humans. Most veterinary patients are handicapped without
a lens yet others do not show significant vision loss. Veterinary
ophthalmology has learned much from the ophthalmic physician and we know
that most dogs will see much better when an artificial lens is implanted
inside the lens capsule. We do this procedure when the client requests it and
the surgery allows it to be done. The estimate you receive before the
surgical procedure will have the option of lens implantation. 

WHAT DOES CATARACT SURGERY INVOLVE?
 

Cataract surgery is performed on an outpatient basis by many veterinary
ophthalmologists, while others will admit the patient for one or two days.
The patient is admitted to the hospital the morning of surgery and an
intravenous catheter is placed to facilitate the administration of drugs.
Drops are placed in the eyes at specific intervals before surgery. General
anesthetic is induced using the most modern agents. An ultrasound may be
performed to examine structures inside the eye that cannot be visually seen.
An electroretinogram [ERG] is performed to determine that there is a
reasonable chance for vision following surgery. This procedure is used if the
cataract has progressed to the point that the ophthalmologist cannot assess
the retina during the initial examination. If the ERG indicates that vision is
not possible, then surgery is not performed and the patient is awakened. If
the ERG shows that vision is possible, the patient is prepared for surgery
and moved to the surgical center. During the surgical procedure, the pet's
respiration and heart rate will be monitored by the surgical technician. An
EKG will be attached to your pet so that the heart can be assessed while the
patient is undergoing surgery. Surgery is performed using an operating
microscope and sophisticated microsurgical instruments. The actual surgical
procedure may last 30-40 minutes and general anesthetic is normally for
60-120 minutes. The cataract is removed by a technique known as
phacoemulsification. The eye is entered with a small incision, the lens capsule
is carefully opened in a technique called capsulotomy, and the lens is
removed by the phaco instrument which emulsifies the lens into a mulch with
ultrasonic waves, and aspirates the remnants. This is the same technique that
is used in human cataract surgery. Although lasers are not involved in this
procedure, it has become common lingo amongst people who have had cataract
surgery by phacoemulsification to say that their cataract was removed by
the laser.

During recovery, your pet will be closely monitored. An Elizabethan collar
(E-collar) is placed on the pet so they will not injure their own eyes during
the first 7 to 14 days following surgery. Postoperative medications are used
to reduce inflammation and preventing infection and are given every 6 hours
for the first 24 hours. 

The first postoperative examination is scheduled for the afternoon the day
following surgery. During that examination, the pressure within the eye will
be examined, the eye is evaluated for inflammation and determination of
possibility of infection will be made. 

WHAT ARE THE COMPLICATIONS OF CATARACT SURGERY?

The success rate in cataract surgery has improved markedly in the recent
years with the advent of newer medications and microsurgical techniques.
Although the success rate has risen dramatically, there are still several
complications that need to be anticipated to prevent them. Intraocular
bleeding, elevation of intraocular pressures [glaucoma], extreme
postoperative inflammatory response, retinal detachment, adhesions and
self-trauma are possible complications. The risk of anesthesia is extremely
minimal. The risk associated with surgery will be explained to you before
the surgery being scheduled. 

COMMON MISCONCEPTIONS REGARDING CATARACTS AND
CATARACT SURGERY
 

The common press contains many misconceptions regarding cataracts and
their treatment. To see an example click here: The Village Vet 

Page maintained by Michael Zigler DVM, Cert.V.Ophthal. Copyright ©1999, Eyevet Consulting Services.
PLEASE NOTE: TIME CONTRAINTS DO NOT PERMIT REPLIES TO PERSONAL E-MAIL.
Updated: Sunday, September 26, 1999.
Note the above information taken from the following url 
where you will find information on eye surgery in small animals

http://www.eyevet.org/

I decided to have cataract surgery done on Heidi because we had three other
dogs. She was the smallest of the bunch and the others were continually
running roughshod over her. I thought it would improve her ability to
communicate with the other dogs--they communicate with each other using body
posture and eye contact, communication that Heidi could no longer understand
because she couldn't see them.  There were times when she was frightened by
all their activity and couldn't see which way to go to get out of the way.

Pre-op care involved putting drops in her eyes the weekend before. Post-op
care involved more drops in the week following surgery and keeping an
e-collar on her so that she didn't accidentally rub her eyes. She had to
spend a couple of days at the vet school following the surgery. Cost for the
surgery was around $1500. She had a lens implant in one eye, but not in the other.

When she came home, it was apparent that she could already see! She did a
play-bow for the first time with our newest dog, a young male. It was
terrific because she could see that he didn't want to hurt her, all he
wanted was to play with her. Her restored vision gave her new confidence.
Her dry eye syndrome also disappeared after the surgery and did not return.

I was very, very pleased with the results of the surgery.

Liese
schnzrs@netins.net
and Heidi @ Rainbow Bridge
 

   To anyone who will or will not have the surgery done for what ever
reason, that isn't what counts. What counts is the love you have for them
and the bond they just seem to instinctively feel.
   Lots of sloppy kisses and a warm hug to all.
Judee & Two-Ton

 Hello to all, I just wanted to comment on this subject because I didn't have
 the option of the cataract surgery with Tuffi because of her heart. She has
 adjusted very well and so have we. Most people think she can still see. If
 she has any vision left at all, it is so minimal that I really can't be
 sure. She has free run in an enclosed back yard with a rabbit and a
 turtle...In case no one knows, rabbits do not see very well during the day,
 and occasionally Tuffi  walks into the rabbit or visa versa, but neither of
 them seem to get upset..Instead of getting upset, they just move over and go
 on their merry way. 

 However, I spend a lot of time talking to Tuffi so that she will know where
 I am at all times, because she does not like to be left outside or in a room
 alone.  If I am sitting in the yard with her and don't say anything for a
 few minutes, she comes to the back door of the house  and wants to come
 inside....When she does that, I just speak to her and tell her that I am
 still outside with her and she comes back to where I am sitting. 

 Also when I start to give her a bite of someting, I tell her first that I am
 giving her something "good'' and she sticks her nose in the air to smell and
 be sure that I am telling her the truth... If I just put a bite up to her
 mouth without telling her first, she jumps as if she is scared because she
 does not know what it is. 

 My husband insists that we encourage her to do things for herself instead of
 helping her, so that she will not become dependent on us for everything... I
 never re-arrange furniture so that she won't have a problem navigating
 around the house. 

 After all that I have read about the possible complications of cataract
 surgery, I am not absolutely sure that we would have it done on Tuffi  even
 if  her heart was o.k. because she is almost  nine years old and can do
 almost anything that she did before the vision loss. 

 I encourage anyone who is thinking about the cataract surgery to ask
 themselves  " am I doing it for my pet/or because I feel sorry for them
 because they can't see?" They don't feel sorry for themselves, only a little
 frustrated at first because of the change, but most of them get past this
 and move right on to do anything that they want to do. 

 I hope this helps someone/anyone  who has a pet who is losing it's vision to
 make the right decision about cataract surgery. And  for those who for  one
 reason or another cannot have the surgery done, financial or otherwise, I
 hope they will not fret about not being able to have it done. 
 Joyce and Tuffi( diabetic dog : diagnosed January 1997)

We visited a wonderful eye vet, Dr. Wolfe, and he told us she was a surgery
candidate.  Pre-surgery we started Voltaren andgentocin three times a day for 7 days.
 We also took her in for a full blood panel during that week.  Her
liver enzymes were a little high, but it was determined that she was ready.
 She has never been regulated, but they did not seem concerned by that. 

Surgery cost $1600 for both eyes, without lens implants. 
He told us that implants were not necessary in dogs and that without them,
their eyes will adjust to almost 100% vision after a year.  The follow up
visits were included for the first 6 weeks.  We had an intensive schedule
of eye drops at first;  voltaren 4 times a day, gentocin 4 times a day, genteel gel
as often as possible.  Follow up visits were the next day, the next week, 
then 2 weeks, 3, 4, and now 3 months.  She wore an e-collar for 6 weeks
and had to be kept calm for four, no shaking or intensive exercise. 
That was the worst part for us and for her!
 She was constantly running the collar into the walls and furniture. 
After the surgery, SHE WAS A NEW DOG!!
 Her beautiful eyes were brown again and she could see
that same day!  Her energy increased and her diabetes
became regulated (unfortunately that didn't last too
long).  She was like a puppy again.  No one can
believe how old she is!  Having the cataract surgery
for Bailey turned out to be a great decision.

Bonnie, bailey (dd, dx 11/97) and Cricket
 

 What are Cataracts? by www.peteducation.com