Frequently Asked Questions About FEVR

  1. What does “FEVR” stand for?

  2. What eye problems can FEVR cause?

  3. How is FEVR Treated ?

  4. How can I tell whether I have FEVR?

  5. What Causes FEVR?

  6. How do I know whether I have Dominant, Recessive or X-linked FEVR ?

  7. Is FEVR similar to other eye diseases (UNDER CONSTRUCTION)

  8. What is the prognosis of someone with FEVR

  9. What does the back of the eye look like for a person with severe FEVR?

  10. Why is oil used in Vitrectomies?

  11. What are retinal folds?

  12. Is surgical treatment available for retinal folds?

  13. How does FEVR affect the learning process in children?

1. What does “FEVR” stand for?

 FEVR is short for Familial Exudative Vitreoretinopathy. A big name but actually it is simply a description of the condition which affects people around the world.

To make it easy to understand, lets break it up…

Familial – This means that it runs in the “family” (i.e. a genetic disease)
Exudative – Refers to the whitish fluid exuded from abnormal blood
               vessels. (see pictures of the fluid)
Vitreo – Refers to a disease of the vitreous humor, the transparent
    gel like substance filling the eye.
Retinopathy – Refers to abnormal changes in the blood vessels of the
eye which feed the retina.  The retina is the thin layer in the
back of the eye which changes light into electrical signals
which are then sent to the brain and decoded, giving us an
image when we open our eye(s).
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2. What eye problems can FEVR cause?

FEVR is a variable disease which means it varies in intensity from person to person.  Severe cases of FEVR can cause a number of eye problems such as

  • Retinal Detachment – Why is a retinal tear considered a serious problem? When a tear in the retina occurs, the liquid in the vitreous cavity may pass through the tear and get under the retina. The liquid collects under the retina and lifts it up off the back wall of the eye. Little by little, the liquid from the vitreous passes though the retinal tear and settles under the retina, separating if from the back wall of the eye. This separation of the retina is called a retinal detachment. Vision is lost wherever the retina becomes detached. Because most tears are located in the peripheral (or side of the) retina, the retinal detachment first results in loss of side, or peripheral, vision. A patient may notice a dark shadow, or a veil, coming from one side, above, or below. In most cases, the entire retina eventually detaches and all useful vision in that eye is lost.

  • Glaucoma – Nonneovascular chronic angle-closure glaucoma

  • Macular Hole, also called Macular cyst, retinal hole, retinal tear, retinal perforation

  • Cataracts (Another Link)

  • Retinal fold present at birth / falciform retinal fold

  • Dragging of the retina / traction of retina (pictures)

  • Abnormal blood vessel growth. Usually in the outer regions of the retina.

  • Bleeding – eye blood vessel breakage / minute vitreous hemorrhages

  • Excessive myopia and anisometropi

  • Flashes & Floaters – Although they’re typically benign, floaters and spots can also signal a serious problem, such as a detached retina.   Flashes of lights and floating spots are the classic warning signs of a detached retina. Get this checked out right away, because prompt surgery can prevent serious vision loss

  • Vitreous Detachment also see Posterior Vitreous Detachment (PVD)

  • Proliferative Vitreoretinopathy (PVR)

  • Giant retinal tear – Just as vitreous pulling creates small retinal tears, it can also cause very large retinal tears. If the retinal tear is very great (one quarter of the retina or more), it is called a “giant retinal tear.” Occasionally, the tear is so large that the retina folds over on itself, like a piece of paper folded in half. A giant retinal tear is a very serious problem.

  • Epiretinal Membranes (Macular Pucker)

Click Here to view a medical paper describing some of the above

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3.  How is FEVR Treated ?

FEVR is a genetic disease. While its causes at this time cannot be treated or cured, its symptoms can be. Each symptom has its individual treatments (see Question 3).  Today effective and aggressive treatment can save much sight. 

MORE ABOUT X-linked FEVRMedical Papers On Treatment

Some Treatments commonly found in FEVR patients

Laser photocoagulation – The application of intense light or laser beams to burn or destroy selected intraocular structures under direct observation, e.g., abnormal blood vessels. More from U-M Kellogg Eye Center  .  Both laser surgery and cryotherapy are done on an outpatient basis. Patients may return to full activity, without restrictions, in a short period of time. Vision may be blurred for several days following laser or cryotherapy. If cryotherapy is used to treat the retinal tear, the eye may be red for several weeks.


Vitrectomy –   A Vitrectomy is used to save vision. This procedure involves the surgical removal of the clear vitreous gel in the eye and replacement during the operation with saline air or silicon oil that completely fills the eye..  The FDA approved the use of silicone oil in 1994, it is a new product for reattaching the retina in certain complicated cases of retinal detachment.  If silicon oil is put in the eye it must be removed at a later time.  A long-acting gas can also be inserted into the eye instead of saline or oil.  The gas bubble, if the face is turned down toward the floor, can help push the retina back onto the back of the eye. NIH currently has a clinical study to way the benefits of gas vs. oil.  Vitreous surgery is performed in a hospital, usually under general anesthesia.  The surgeon uses a fiber optic light to illuminate the inside of the eye and other instruments inside the eye, such as forceps, and scissors, to do the surgery.

A Cataract, which can be taken care of later, is a major risk factor in this procedure. In one study, 63% of eyes that had had a vitrectomy developed cataracts compared to only 4% in the non-vitrectomised eye. Fortunately, vitrectomy is only used to prevent a more serious form of vision loss, and when treatment is recommended by an ophthalmologist it is clearly necessary.

more on Vitrectomy

Scleral Resection – Scleral resection is a surgical technique done to repair retinal detachment and to relieve traction (dragging) of the retina common in FEVR patients.  In the procedure a small section of the eye wall (scleral) is removed.

Scleral Buckling – Scleral buckling is a surgical technique to repair retinal detachments due to traction which is seen in FEVR patients. In traction, the retina is pulled towards it’s outer edges. When this happens tearing of the retina and detachment can occur. A Silicone rubber band is placed onto the scleral (the white out side of the eye ball) Silicone, a synthetic rubber compound of silicon, oxygen and carbon, is hydrophobic and stable within a very wide temperature range. Silicone retinal implants are economical, soft, biochemically inert, non-allergenic, and are well tolerated by the body. In vivo, they remain soft and retain their other physical properties for an extended period. They also retain these properties in extended storage. Buckling is sometimes also performed after scleral resections.

Glaucoma Surgery
Retinal detachment surgery – About Pneumatic retinopexy, Scleral buckling, and Vitrectomy from the U-M Kellogg Eye Center
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4. How can I tell whether I have FEVR?

Seeing a retinal specialist is the first step in determining whether you have FEVR.  A complete ocular (eye) examination needs to be performed including:

  • Fundus biomicroscopic examination – A fundus exam is an exam of the back of the eye known as the retina.   The slit lamp, also known as a biomicroscope, is one instrument used by ophthalmic professionals to view the retina.  A slit lamp basically functions as a sophisticated light source and super magnifier. In the hands of a trained professional, it can be used to look at the surface, and anterior and posterior segments of the eye. It is an essential tool for contact lenses as well and is especially helpful in viewing lens positioning, movement, and surface condition.

  • Fluorescein angiography test. In this test, fluorescein dye is injected into a blood vessel in the arm. After fluorescein dye is injected into an arm vein, rapid sequential photographs are taken of the eye as the dye circulates. The photographs are  used for evaluating retinal and choroidal blood vessels, as well as changes in the pigmented layers of the eye. They can also show leakage of fluorescein dye from damaged blood vessels.

After the retinal specialist determines that your case may be FEVR genetic testing and a family history evaluation by a genetic counselor can be done.

The majority of cases of FEVR are dominant.  The gene for the dominant form of FEVR has been found an a genetic test has been developed by the Canadian lab who discovered the gene. The test is not commercially available yet.  (Return here for soon to come info on this)

In some cases, a mutation of the gene causing Norrie Disease has caused the X-Linked form of FEVR, the second most common form of FEVR.  In the X-linked form of FEVR only males in the family have the disease.  A genetic test may be done to determine this.  Click below for details.


Unfortunately, in the most rarest cases, recessive, the gene causing they FEVR has not been found.  We are currently looking for families with this form of FEVR.  A study to find this form of FEVR is currently in the approval stage.  (Click here for more on the study)

The symptoms of FEVR are like many other retina eye problems.  They can include:

Flashes and Floaters

Symptoms of retina detachment – Flashing lights in one eye, Floaters, and Gray curtain or veil moving across your field of vision

more soon to come…

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5. What causes FEVR?

All three forms of FEVR are caused by defective gene . The three forms of FEVR are recessive, dominant and X-linked. 

In the X-linked form of FEVR only males have the disease.  In some cases, the X-Linked FEVR is caused by a mutation of Norrie disease (ND). Mutations in the NDP gene are associated with a spectrum of retinal findings ranging from Norrie disease (ND) to X-linked familial exudative vitreoretinopathy (FEVR), including some cases of persistent hyperplastic primary vitreous (PHPV), Coats disease, and advanced retinopathy of prematurity (ROP)

A test for the mutation is available.   There is still debate as to how many cases of x-linked FEVR are caused by the mutation. 


For the latest paper on the causes of the 3 dominant genes (click here)

     Here are some helpful links about recessive, dominant and X-linked inheritance


Here are some Medical Papers On each form of FEVR

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6. How do I know whether I have Dominant, Recessive or X-Linked FEVR?

Although genetic testing is the only “full proof” way to tell which version of FEVR a person has, a family survey can sometimes eliminate the options.  X-linked for example, runs only in the males of the family so if a girl in the family has FEVR you know it is either dominant or recessive.   In Dominant families the disease tends to show up in many generations.  Recessive is more rare than dominant.


As of yet, no test for the recessive or dominant gene exists.  More research is needed to make this possible.  The dominant gene has been identified to be on the 11th chromosome but it’s exact location has still not been found. 

If you or your family has FEVR and would be interested in helping to find the gene for recessive & dominant click here.

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6. Is FEVR similar to other eye disease?

Yes, FEVR is similar to:

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7.  What is the prognosis of someone with FEVR 

FEVR is a variable disease. The level of severity in a person can range from no symptoms to severe symptoms. The severity can even vary between eyes of the same person. In short, it’s hard to predict with certainty the prognosis of any one person. This uncertainty of taking things “one day at a time” can be very frustrating to for families.

Medical papers on prognosis

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9. What does the back of the eye look like for a person with severe FEVR

View larger version (55K):
[in a new window   Figure   Fundus photographs of the left and right eyes of the proband. (A) Right eye: temporal periphery shows white preretinal mass with retinal traction. This eye has previously undergone a pars plana vitrectomy together with endophotocoagulation (the scars from which can also be seen here). (B) Left eye: distortion of major retinal vessels at the optic disc due to vitreoretinal traction

  Right Eye Left Eye View Source Paper

Photo of a detached retina

Detached Retina The billowed-up retina has detached from the choroid layer beneath it. Detachments can be from tears or holes in the retina (rhegmatogenous), or from fluid accumulation between the retina and underlying layers (exudative).
SLIDES OF THE EYE ophthalmologic images

Other images

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10.  Why is oil used in Vitrectomies?

In many cases a replacement solution that can be thought of as saline or Ringers-like solution is put back into the eye after vitrectomy. The other choices are gas, which acts as a tamponade to hold the retina in place or Silicone oil. There are a couple of gases used routinely, namely SF6 (sulfahexachloride) and C3F8 (perflouro-octane). The second one expands more and lasts longer (slower absorption). Both are used in various concentrations like 100% or 75% etc, depending on the expansion and lasting needs. Silicone oil is a heavy solution which is used in difficult eyes to attach and is left in the eye for a long period of time then needs to be surgically removed (by another vitrectomy). It will never absorb.

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11.  What are retinal folds?
The retina lines the inside of the back portion of the eyeball. It is multi-layered membrane about two tenths of a millimeter thick. Nerves from the retina exit the eye through the optic nerve and travel to the brain. Light is converted to an electrical signal in the retina and carried to the brain by these nerves.
The central visual center of the retina is a region less than 1 mm in diameter and is responsible for our detailed vision. If this region is damaged the vision can drop to 20/200 or less. 20/200 means that the person can see at 20 feet what a normal person could see at 200 feet and is one of the definitions of legal blindness. FEVR leads to pulling on the visual cent