What is a lens luxation?

A lens luxation is instability of the lens.  The lens is suspended behind the pupil with small fibers termed zonules.  Breakdown of these zonules result in instability and possible movement of the lens within the eye.  The types of luxations include:

• Subluxation - partial but not complete breakdown of the zonules resulting in a lens still in its proper location, but loose.
• Posterior luxation - complete breakdown of the zonules with the lens located behind the iris.
• Anterior luxation - complete breakdown of the zonules with movement of the lens in front of the iris.  This is considered an emergency.

What causes a lens luxation?

The most common cause in the dog are genetic.  Many breeds and, even mixed breeds, have been found to have a genetic lens luxation.  The breeds with the highest incidence of lens luxation include Terriers and mixed Terriers, Miniature Poodles, American Cocker Spaniels, Border Collies, Shar Pei, German Shephards, and Blue Heelers.  The average age of onset for generic lens luxation is 3-6 years.

Other causes of lens luxation include intraocular inflammation, advanced cataracts, senile changes, glaucoma, and trauma.

Why are lens luxations important?

Unfortunately, lens luxation is highly associated with the development of glaucoma, a painful and blinding condition of the eye.  Anterior lens luxations are the most urgent leading to glaucoma in 73% of dog eyes, thus considered an emergency.  However, even posterior luxations and subluxations can lead to glaucoma.

What is the treatment for a lens luxation?

The treatment for lens luxation varies with the type of luxation.  Anterior lens luxations cause significant disruption of the fluid within the eye resulting in significant increases in intraocular pressure, a very painful and potentially blinding condition.  The only way to relieve the situation is to surgically remove the lens through a large corneal incision.  An anterior lens luxation is considered an emergency and should be treated immediately.

Posterior luxated and subluxated lens can be treated more conservatively with topical medications to constrict the pupil and decrease the intraocular inflammation.  However, these eyes must still be monitored closely for the development of glaucoma.

Even if the lens is completely removed, the eye still has the potential for vision, just not optimal vision.  Eyes without lenses are very farsighted.  For this reason, an artificial lens can be placed in certain circumstances if a luxated lens needs to be removed.