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Juvenile open-angle glaucoma PDF Print E-mail
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Wednesday, 13 January 2010 18:48

Juvenile open-angle glaucoma (JOAG) is a rare, often inherited condition affecting 1 in 10,000 babies. It develops after the 3rd year of life and is therefore seen in older children and adolescents. It is characterized by underdevelopment of the outflow channel of the eye (anterior chamber angle). The fluid (aqueous humour) produced behind the iris, is unable to drain through the sieve-like structure (trabecular meshwork) back into the bloodstream, which in turn causes a raise in intraocular pressure. It is also associated with nearsightedness (myopia) where light rays come into focus in front of instead of on the retina.

There is evidence that juvenile glaucoma is caused by a genetic defect, referred to as autosomal dominant inheritance. This means that both males and females are equally affected because the gene is found in one of the autosomes (any chromosome other than X or Y); means a child of a parent found to have the gene will have a 50% chance of inheriting juvenile glaucoma. It appears to be more common in males than females, and it affects both eyes in two-thirds of children. However, the older the child is, the more likely it is that the glaucoma will affect only one eye.

Unlike congenital glaucoma, signs and symptoms of juvenile glaucoma may go undetected until problems with vision occur.  Where there is a family history of glaucoma, regular eye checks are important from a young age.

TREATMENT
Checking and treating intraocular pressure in young children is very difficult and the most effective course of treatment is surgery.

Goniotomy - A very fine needle knife is used to make a small cut in the sieve-like system (trabecular meshwork) to open up the underdeveloped channel and to allow the fluid to drain. A special lens called a gonioscope is used so the surgeon can see inside the eye. A second goniotomy may be required if the pressures does not lower sufficiently.

Trabeculectomy - It may be necessary for the surgeon to to perform this procedure to create a new drainage channel for the fluid to pass through. A flap is made over a small hole in the tough outer wall of the eye (sclera) to form a new drainage route for the fluid to leave the eye under the thinner skin covering the sclera (conjunctiva).

Tube shunt - A device called a shunt is used to create an artificial passage to direct intraocular fluid out of the eye. A common form of implant is called the Ahmed valve, which has a valve mechanism to reduce the chance of the eye pressure going too low.

Cyclodiode laser - The laser is used to reduce the production of aqueous humour by destroying part of the ciliary body where the fluid is produuced.  The laser beam travels through the white part of the eye through the surface behind the iris. Some of the ciliary body remains and less fluid will be produced to effectively lower pressure within the eye.

The surgeon may prescribe medication in the form of eye drops to help reduce intraocular pressure. Some complications can occur, such as developing a lazy eye (amblyopia); nearsightedness (myopia; detached retina, irregular cornea (astigmatism) and lens dislocation. Regular check ups are advisable, as even after effective treatment, eye pressure can creep up in later life. Of course this can still be treated, but the earlier this is identified, the more effective the treatment. If the condition is caught early, the outlook is good in round 80-90% of children affected.

nerve fibre layer scan

Scan of optic nerve -GDx scan.

Last Updated on Thursday, 21 January 2010 23:30