At
first I'd like to give a brief introduction. The bird's eye shows some
basic structures that are very similar to the human's eye. A bird's eye
has a spherical shape and the biggest part of the eyeball is invisible
since it is located inside the skull. Only a small part of the eye is
visible from the outside. If you have a close look to your bird, you
can easily see that the eyes are curved. What you see is the cornea,
the outer part of the eye. In a healthy bird the cornea is clear and
smooth. And also you can see reflections of the surrounding, e. g. the
light of a window, on the cornea. The photo on the right shows the
healthy cornea of a lineolated parakeet.
The anterior chamber is
located right behind the cornea. This space is filled with a liquid
called "aqueous humor". Right behind the anterior chamber the
iris and the pupil are located. In most budgies, the iris is white.
Young budgies and some older ones with special colour varieties have a
dark iris. The pupil of most birds is black or red in case it's an
albino or lutino. Some budgies show a pupil with a violet colour.
Description of the figure on the right: Eye 1 is most typical for
budgies: the pupil is black and the iris white. Eye 2 belongs to an
adult budgie with a black iris and black pupil. The reddish colour of
the iris and pupil is typical for lutino budgies (and albino birds as
well). Eye 4 belongs to a fallow budgie, the pupil is slightly purple
and not black.Behind the pupil lies the small posterior chamber and it is followed by the lens. The posterior chamber is liquid-filled like the anterior one. And again, behind the lens another liquid-filled chamber is located. For more information on the anatomy of a human's eye see Wikipedia
.
Leaking of aqueous humor
Since
the largest part of the eye is liquid-filled, any kind of injury caused
by a sharp object or a rupture caused by a collision can lead to a
leaking of aqueous humor. Once this liquid flows, this can cause severe
problems and a bird owner should contact an avian vet or an
ophthalmologist for animals as soon as possible. A leaking of aqueous
humor can be recognized easily: The eye seems to be teary and there are
yellowish crusts around the eye sticking to the feathers. Also the bird
keeps the eyelids closed. The photo on the right shows a budgie whose
right eye has been injured and therefore a leaking of aqueous humor
occurred. In case you notice the above mentioned symptoms, you should
take your bird to a vet immediately. If you don't, the eye will dry
out soon and your bird will lose the eyesight.
Corneal injuries
DDue to different reasons a bird's cornea can be injured. Quite often
tiny objects slide under the eyelids and scratch the cornea's surface.
Eye infections like a conjunctivitis often follow these injuries. If a
vet doesn't recognize the corneal injury, most birds suffer from a more
or less severe visual impairment for the rest of his (or her) life.
Therefore it's always important to make sure that an eye infection is
not caused by a corneal injury. Some special medical eye drops help to
figure this out: Once they touch the cornea, they make the injuries
become fluorescent.
Another source of danger in typical households is the kitchen. In case
a bird gets in touch with hot steam, a burning of the cornea can be the
result. After the injury, most birds keep their eyelids closed and they
swell. Also the cornea becomes greyish. If it's severely burned, it can
even dissolve from the eye which is very alarming condition.
Please make sure to take immediate action if your bird
suffered a corneal burn. The faster you take your bird to a vet the
more likely it is that your feathered friend will not lose his
eyesight. Because it is better to be save then sorry, you should
never let your birds fly into your kitchen while you are cooking. And
please don't leave them unattended when there is hot steam anywhere.
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