Alport Syndrome and the Eyes

         

globe anatomy
anatomy of the eye (click on image to enlarge)

Alport syndrome is an inherited condition that prominently affects the kidneys.  It may also cause hearing loss and affect the eyes.  It is due to an alteration in genes that codes for a protein called collagen.  Alport syndrome affects about 1 in 5,000 to 10,000 people in the US.  Depending on which gene is affected, there are three types of Alport syndrome:

1.) X-Linked Alport syndrome is the most common type (80% of cases) and it affects males more severely than females.  

2.) Autosomal recessive Alport syndrome must be inherited by an affected gene in both parents.  It is rare and affects males and females equally.  

3.) Autosomal dominant Alport syndrome is inherited from one parent with an abnormal gene.  It affects males and females equally and may be less severe.

How does Alport syndrome damage the kidney?

            Alport syndrome causes abnormal collagen to form.  There are many different types of collagen, which is deposited outside the cells to give structural and functional support to cells in the body.  The collagen (type IV) affected by Alport syndrome is important for kidney function.  It affects the glomerulus, which is the blood filtering unit of the kidney.  The decline in kidney function may eventually require kidney transplantation.  

What kidney symptoms does it cause? 

            Alport syndrome causes blood in the urine, the most common early sign of disease.  Urinalysis reveals protein in the urine, as well.  Related to damage in the kidney, Alport syndrome may also cause swelling (edema) of the extremities (especially, the legs).  High blood pressure is also common.  Other symptoms include weakness, fatigue, loss of appetite, poor digestion, excessive thirst, and frequent urination.

How are the eyes affected?

            Alport syndrome affects the cornea, lens, and retina of the eye.  The changes in the eye are more common with X-linked and autosomal recessive disease than in autosomal dominant cases.  

The cornea is the clear front window of the eye.  Alport syndrome may cause recurrent corneal erosions (similar to a scratched cornea, but without trauma). Symptoms include intermittent pain, redness, tearing, blurred vision.  PPCD is a corneal dystrophy that may occur and cause similar symptoms.      

The lens is positioned behind the colored iris and focuses light onto the retina in the back of the eye. Alport syndrome may cause an unusual bulging of the anterior surface of the lens (anterior lenticonus), which may require the use of glasses and may cause cataract formation.

What is the retina?

            The retina is a thin layer of delicate nerve tissue, which lines the inside wall of the eye like the film in a camera.  In the eye, light is focused onto the retina, which “takes the picture” and sends the image to the brain.  The retina has two main areas.  The macula is the central area that gives you sharp, central vision and color vision.  The peripheral retina is the part of the retina that gives you side vision and night vision.

How is the retina affected in Alport syndrome?

            Alport syndrome causes abnormalities of the inner the retina, especially evident in the macula.  Inner retinal deposits cause no symptoms, but may be mistaken for dry macular degeneration on a routine eye exam.  These deposits rarely cause symptoms; though a hole in the center of the retina (macular hole) has been reported. 

There appears to be an increased risk of lattice degeneration in Alport syndrome. This may increase the risk of retinal detachment later in life.

How are eye problems in Alport syndrome diagnosed?

            An ophthalmologist may diagnose eye changes on a careful routine examination.  Sometimes, special scans and photographs are needed.  The patient may perform vision checks at home with the help of an Amsler grid.  Distortion of the grid indicates macular problems and warrants a prompt eye exam. 

How are eye problems associated with Alport syndrome treated?

            No treatment is needed if the vision is not threatened.  Corneal problems may be treated with eye drops and contact lenses.  Only rarely is surgery needed.  Lens changes may be compensated for with the use of prescription glasses.  In some cases, cataract surgery is needed.  Only in severe cases of retinal disease is treatment needed by eye injections or surgery.  

By Scott E. Pautler, MD

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