Everything about Ectopia Lentis totally explained
Ectopia lentis is a displacement or malposition of the
eye's
crystalline lens from its normal location. A partial dislocation of a lens is termed
lens subluxation or
subluxated lens; a complete dislocation of a lens is termed
lens luxation or
luxated lens.
Ectopia lentis in dogs and cats
Although observed in humans and cats, ectopia lentis is most commonly seen in
dogs.
Ciliary zonules normally hold the lens in place. Abnormal development of these zonules can lead to primary ectopia lentis, usually a bilateral condition. Luxation can also be a secondary condition, caused by trauma,
cataract formation (decrease in lens diameter may stretch and break the zonules), or
glaucoma (enlargement of the globe stretches the zonules). Lens luxation in cats can occur secondary to anterior
uveitis (inflammation of the inside of the eye).
Anterior lens luxation
With anterior lens luxation, the lens pushes into the
iris or actually enters the
anterior chamber of the eye. This can cause
glaucoma, uveitis, or damage to the
cornea. Uveitis (inflammation of the eye) causes the pupil to constrict (
miosis) and trap the lens in the anterior chamber, leading to an obstruction of outflow of
aqueous humour and subsequent increase in ocular pressure (glaucoma). Surgery to remove the lens has a higher success rate (retained vision and normal intraocular pressure) when it's performed before the onset of secondary glaucoma. Glaucoma secondary to anterior lens luxation is less common in cats than dogs due to their naturally deeper anterior chamber and the liquification of the
vitreous humour secondary to chronic inflammation. Anterior lens luxation is considered to be an ophthalmological emergency.
Posterior lens luxation
With posterior lens luxation, the lens falls back into the vitreous humour and lays on the floor of the eye. This type causes less problems than anterior lens luxation, although glaucoma or ocular inflammation may occur. Surgery is used to treat dogs with significant symptoms. Removal of the lens before it moves to the anterior chamber may prevent secondary glaucoma. Other signs of lens subluxation include mild
conjunctival redness, vitreous humour degeneration, prolapse of the vitreous into the anterior chamber, and an increase or decrease of anterior chamber depth. Removal of the lens before it completely luxates into the anterior chamber may prevent secondary glaucoma.
Breed predisposition
Terrier breeds are predisposed to lens luxation, and it's probably inherited in the
Sealyham Terrier,
Jack Russell Terrier,
Wirehaired Fox Terrier,
Tibetan Terrier,
Miniature Bull Terrier,
Shar Pei, and
Border Collie. The mode of inheritance in the Tibetan Terrier is likely
autosomal recessive.
Labrador Retrievers and
Australian Cattle Dogs are also predisposed.
Systemic associations in humans
In humans, there are a number of systemic conditions that are associated with ectopia lentis:
More common:
Further Information
Get more info on 'Ectopia Lentis'.
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