Download Lens Luxation and Subluxation - Saint Francis Veterinary Center

Lens Luxation and Subluxation
Rhea V. Morgan, DVM, DACVIM (Small Animal), DACVO
BASIC INFORMATION
Description
Luxation is complete dislocation and subluxation is partial dislocation of the lens from its normal position within the eye. The lens
is suspended and centered behind the pupil by a ring of tiny fibers.
When these fibers degenerate or break, the lens becomes unstable
and may move.
Causes
The terrier breeds, border collie, German shepherd dog, and
Chinese shar-pei are predisposed to primary lens luxations,
because they have an inherited tendency for the suspensory fibers
to break. Although lens movement may occur in only one eye initially, the other lens is also prone to luxation. Most affected dogs
are 3-7 years of age.
Secondary luxations or subluxations can occur when the eye
stretches as a result of glaucoma or the suspensory fibers are destroyed
by inflammation (uveitis). Secondary luxations are the most common
type in the cat. Rarely, subluxations may occur from tumor growth or
serious infection behind the lens. In some instances, the cause of the
lens movement is not identified and is termed idiopathic.
Clinical Signs
No specific clinical signs may occur with posterior subluxations
and luxations (those in which the lens remains behind the pupil).
In these cases, the lens movement may be discovered only when
the eye is examined.
Forward (anterior) movement of the lens can disrupt the normal flow of fluid in the eye and cause acute, serious glaucoma.
Glaucoma is most likely when the lens becomes trapped within or
in front of the pupil. Signs of acute glaucoma include pain (squinting, blinking, and lethargy), bluish-white discoloration of the cornea, redness, and blindness in the eye. If the lens is opaque from
a cataract, then the front of the eye may suddenly become very
white. Because the lens is most likely to move when the pupil is
dilated (at night, in darkness), it is common for signs of lens luxation to first be present in the morning.
If the lens luxation is secondary to another eye condition, then
signs of that condition may also be noted.
Diagnostic Tests
Diagnosis is confirmed by a thorough eye examination, which
includes glaucoma testing. If the eye is opaque and an adequate
examination cannot be performed, your pet may be referred for
slit-lamp examination or an ocular ultrasound or both. A search for
an underlying cause is also indicated if lens movement is thought
to be secondary.
TREATMENT AND FOLLOW-UP
Treatment Options
Posterior luxation and many subluxations of the lens require no
treatment other than that indicated for the underlying cause. In
contrast, acute anterior subluxations and luxations are usually considered emergencies because of the extremely high pressures that
can develop in the eye within a few hours.
Initially, the animal may be given medications to decrease the
pressure in the eye. If there is a chance that vision can be saved in
the eye, your pet may be referred to a veterinary ophthalmologist
for surgical removal of the lens (lensectomy). This type of surgery
is very similar to that performed for cataracts and requires hospitalization and general anesthesia.
If the affected eye is blind, then an attempt to control the glaucoma may be made with medications. If the pressures cannot be
controlled, removal of the eye may be recommended. Treatment of
underlying conditions is also instituted.
Follow-up Care
Lensectomy surgery requires a major financial and time commitment on the part of the owner. Postoperatively, medications must be administered several times daily for weeks to
months, and numerous recheck visits are needed. Close monitoring for complications, such as postoperative uveitis, glaucoma, and retinal detachments, is important. Often the animal
must wear an Elizabethan collar for 3-4 weeks while the incision is healing.
Eyes that are treated with medications alone also require longterm monitoring, because the medications can become less effective over time. In dogs with primary lens luxation, the opposite
eye must be monitored periodically for evidence that the lens is
becoming loose. If any lens movement is detected, then lensectomy may be recommended in that eye.
Prognosis
Prognosis is highly variable, depending on which direction the
lens moves, whether the eye was blind before the movement,
and whether the luxation is primary or secondary. In dogs with
primary, acute, anterior lens luxation, time is of the essence.
Permanent blindness can occur within a few hours due to the
extremely high intraocular pressures that occur. If these pressures are alleviated and the lens is removed, then the shortterm prognosis can be good. Postoperatively, many of these
dogs are still prone to glaucoma and may require lifelong
therapy.
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