Causes of Blindness

I. Von Hippel-Lindau (VHL)

II. Diabetes Mellitus (AKA Diabetes)

III. Retinopathy of Prematurity (ROP)

IV. Retinitis Pigmentosa (RP)

V. Leber’s Congenital Amaurosis  (LCA)

VI. Glaucoma

VII. Coats' Disease

What is Von Hippel-Lindau (VHL)?

Von Hippel-Lindau (VHL)  is a hereditary disease caused by a flaw in a tumor suppressor gene that regulates cell growth. VHL causes blood vessels to sprout up as tumors in the eye, the spinal cord, and the brain, especially in the cerebellum.

In 1904 a German ophthalmologist Eugen von Hippel first described angiomas, or blood vessel tumors, in the eye, and in 1924 Arvid Lindau described angiomas of the cerebellum and spine.  

VHL occurs in approximately one in 36,000 births and it is listed as a rare disease.  The average age of diagnosis is 26, however tumors may be present at birth and may begin growing well into old age.

How does it affect patients?

The longer VHL patients live, the more likely a tumor will appear. Patients with VHL live daily knowing at some point a headache or a funny heartbeat may be a tumor that threatens their functioning, their independence, their dreams and their very lives.

Many of these patients know first hand what will happen, as they often have fathers, mothers, brothers or sisters who go blind, have an open craniotomy or a surgery to remove an abdominal cancer. They have seen family pass away from VHL, often after multiple tumors and surgeries throughout their body.  

What is treatment like?

The retinal specialists will laser or freeze the vascular tumors formed in the retina by the VHL.

If a tumor is found it is often lasered. Other times it is treated with injections of antivegf medicine to stop the tumor growth, a treatment that was developed in the last decade. These treatments can also be combined.

Sometimes the patient will develop a retinal detachment and a vitrectomy--a removal of the eye’s gel and scar tissue from the tumor-- is required.  A bubble of oil or gas may be injected to help keep the retina attached. After this procedure the patient must keep their head pointed to the ground so that they heal properly.

Some VHL lesions in the retina are inoperable at presentation, or carry a poor prognosis into surgery.  Even after surgery, when the retina is initially successfully attached, the retina can redetach post operatively.  

With or without operation, the eye can shrink or become scarred. If this occurs, patients can visit an ocularist to fashion a prosthetic eye by using pictures and molds to match the other eye and eye socket.  

What is the latest in treatment technology?
 

Photodynamic therapy (PDT) is a new type of laser treatment that allows us to directly treat some of the smaller and medium-sized tumors near the optic nerve. Injections of antivascular endothelial growth factor (antivegf) directly into the vitreous cavity (the jelly of the eye) may shrink vascular tumors in some cases. Some retinal surgeons combine the two, but these are still primitive weapons in treating VHL.

Scientists have discovered a tumor suppressor gene on chromosome 3 that appears to be the cause of VHL. This knowledge may one day lead to genetic treatment and a cure.

Until then patients, doctors, and families battle on.

How did VHL affect Damian?

In Damian’s situation, he lost all the vision in his right eye starting at 11 years old, definitively ending his dreams of being in the air force and an astronaut.  A healthy child with both parents may find visits to the doctor for strep throat or ear aches to be extremely stressful. Imagine sitting alone with an oncologist at the tender age of 11 and finding out tumors are growing in your eye, blinding you.

In response patients often develop an active psychological mechanism to prepare for extreme challenges.

****Note - (NEEDS more explanation of how it affected him physiologically and psychologically) and (add into Damian’s story or cut altogether) ***

What was treatment like for Damian?

In Damian’s case the tumor originated and was part of the optic nerve, the main cable that is filled with nerve fibers that transmit all the visual information to the brain to see.  Lasers used at that time could not be used to laser the tumor as it would heat and destroy the optic nerve. The tumor can also bleed into the vitreous gel, and may leak fluid into the retina, which being an electrical network, short circuits with fluid and will be severely damaged by blood from the growing tumor.

(put in line with Damian’s story, split into treatment if necessary)

“A special kind of patient needs a special kind of doctor.”

Why is diabetes so common, and why are its effects so severe?

Diabetes remains the most common cause of blindness in the United States in young to middle aged adults for three main reasons:

Diet: Controlling diet is difficult.

False optimism: Most patients believe they have a milder type of diabetes early on, but it advances to affect the body’s blood circulation, which damages the kidneys, eyes, brain and heart.

Delayed effects: Patients feel no ill effects for years while their sugar is out of control. Only much later will the damage manifest as complications in health.

The delay in “punishment” from high blood sugar means that early warning and adjusted diet are essential to prevent diabetes from ravaging the body. Patients must understand that years of high blood sugar caused by poor diet results in blindness, strokes, heart attacks, and loss of limbs. 

Sometimes witnessing a loved one succumb to diabetes, experiencing kidney failure, amputation or blindness will cause a patient to improve their diet and blood sugar control. But because the realities of future damage are often not fully understood, patients don’t manage their blood sugar properly. This continues until they experience vision loss, a heart attack, or kidney failure, and though they respond with diet management, the majority of damage has been done and further loss will likely ensue.

How does a disease of increased blood sugar complicate health?

When sugar is too high in the blood it damages the blood vessels.  The capillaries-- the smallest blood vessels in the body-- deteriorate over years of poor sugar control. In addition, pericyte support cells that help repair blood vessels die off, accumulating damage over time. Most of the damage is not reversible, although better sugar control usually decreases the severity of the problems.

The nature of the disease carries a momentum that too often runs its course despite medical advice and treatment. Loss of function often occurs during the prime years of a patient’s life, starting as a young adult through their middle-aged years and beyond.

How does diabetes result in vision loss?

Long term blood vessel damage results in the eyes not receiving proper nutrition and accumulating waste that would normally be disposed of. Early changes that appear in the eyes of diabetic patients are called background diabetic retinopathy.  These are hemorrhages, small aneurysms, and small infarcts of the retina that can be seen in exams or photographs.  

The blood vessels at this stage are like garden hoses that have small holes along their course. These damaged vessels leak fluid throughout their length, where normally they should only exchange nutrients and waste at the capillaries (the end of the hose).  These leaks allow blood, cholesterol and watery serum to leak out into the retina. The fluid distorts the shape of the retina and short-circuits the retinal neural network, resulting in loss of vision.

When this happens on the macula, the location of the retina responsible for our center of vision, it is known as macular edema. The irregular pooling of fluid in the macula disrupts a delicate structure vital to normal vision. It is difficult to cure and can last for months to years even with aggressive treatment.

If sugar remains out of control the patients may progress to the next stage called proliferative diabetic retinopathy, which includes bleeding into the vitreous cavity of the eye and “new” growth of fibrous blood vessels from the retina.

(proliferative diabetic retinopathy with large leashes of new blood vessels and white dots from laser treatment [confirm with dad])

These new vessels disrupt the structure of the eye and must be treated.  Blood and scar tissue are leftover, and when they are removed vision improves.

Patients with proliferative diabetic retinopathy often lose peripheral vision due to weak peripheral circulation.  Some patients develop extensive growth of new blood vessels in the retina which can result in a retinal detachment.  

(Severe Diabetic Traction Retinal Detachment confirm with Dad placement in description)

Often despite the physician’s best efforts, the patient continues living with vision loss even after all possible treatment is given.

How is diabetic vision loss treated today?

Treatments for leakage of fluid and macular edema involve light laser to the macula, injection of anti-vegf agents directly into the vitreous cavity of the eye, and injection of steroids around or directly into the eye.

When bleeding occurs in proliferative diabetic retinopathy, heavy laser called pan retinal photocoagulation (PRP) is used to burn the peripheral retina causing the new blood vessels to shrink back.  Anit-vegf injections can also be used, but last only 6 to 10 weeks, and need to be repeated frequently to suppress the new growth of blood vessels until laser treatment is possible.  Retinal surgeons remove the resulting blood and scar tissue to improve vision.

Almost every tool a retinal surgeon has may be used to treat diabetic retinopathy, and often ophthalmologists combine treatments because complications occur simultaneously.

For the patients that have advanced diabetes, the field of vitreoretinal surgery and other medical treatments continue to grow and evolve.

What is prematurity?

When a baby is born before it is fully developed it is considered premature.  Mild prematurity is usually not a problem, but in cases of severe prematurity, when the baby is delivered months too early (less than 31 weeks of gestation), or the baby is 1250 grams (about 2.75 pounds), the eyes are at risk for blindness.

How does prematurity of birth result in ROP and vision loss?

During a fetus’s growth in the mother’s womb, its retinal blood vessels normally grow out from the optic nerve to the edge of the peripheral retina.  However in retinopathy of prematurity, the blood vessels have not had enough time to grow to the edge of the peripheral retina, so large patches of retina are present without any blood vessels.

This lack of blood flow makes the retinal cells release chemicals for new blood vessel growth. The new blood vessel growth, known as fibrovascular proliferation or neovascularization, causes excessive scar tissue and bleeding that result in vision loss.

If the baby is fortunate their retinal blood vessels fill in the missing peripheral areas naturally, the baby is deemed resolved and no treatment is necessary.

How is Retinopathy of Prematurity Treated?

Treating retinopathy of prematurity requires limiting the growth of new blood vessels.  In moderate cases, laser ablation or occasionally cryotherapy (freezing the retina without blood vessels) is utilized to treat the areas of retinopathy.   In severe cases close to the macula and optic nerve, antivegf injections are administered to the vitreous cavity of the eye if laser proves insufficient. If those treatment methods fail to stop the growth of new blood vessels, or if the blood vessels have turned into scar tissue and detached the retina,  a vitrectomy or scleral buckle is required to try to reattach the retina.

Do people who have had ROP as infants have higher risk of other eye disease as adults?

Unfortunately, even if a premature infant is lucky enough to escape ROP, as an adult they may have issues with their eye muscles (strabismus), cloudy lenses (cataract), high pressure in the eye (glaucoma) or retinal detachments.