Genetic Eye Diseases

There are about 350 inherited eye illnesses, including albinism, aniridia, colorblindness, corneal dystrophies, glaucoma, keratoconus, Leber congenital amaurosis, night blindness, retinitis pigmentosa, and retinoblastoma.

 

What are genetic eye diseases?

Genes have a crucial impact in eye illnesses, which are common in both children and adults. Genetic factors account for more than 60% of all incidences of juvenile blindness (congenital glaucoma, ocular malformations, atrophy of the optic nerve and retinitis pigmentosa). In adulthood, genetic factors have been linked to major eye illnesses such as glaucoma and macular degeneration.

Most eye disorders with a genetic component are passed on from parents to children and can damage various eye tissues such as the macula, cornea, and optic nerve. Over 60% of juvenile blindness cases are caused by illnesses having hereditary components.

 

What are the benefits of genetic diagnosis for the patient?

Vision abnormalities that develop in apparently healthy eyes are also influenced by heredity. There is mounting evidence that the most prevalent visual disorders in children and adults are inherited. Strabismus (an ocular misalignment also known as cross-eyes), amblyopia (lazy eye), and refractive problems such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism are among the conditions on the list. Up to 40% of people with certain forms of strabismus have a family history of the condition.

The clinical diagnosis is supported and confirmed by genetic testing. This is critical in some visual problems since overlapping symptoms are difficult to identify. This is true of retinal dystrophies, for example. Correct diagnosis is critical for determining prognosis and avoiding confusion and improper therapy.

 

Congenital Cataract

A congenital cataract is a clouding of the normal lens of the eye that occurs at birth. Congenital cataracts may need to be removed through cataract surgery when the kid is still a newborn, depending on the density and location of the opacification, to allow normal visual development and prevent amblyopia and even blindness.

However, some hereditary cataracts damage just a tiny portion of the lens of the eye and do not impair vision sufficiently enough to require surgery.

 

Cataract Causes

Congenital cataracts can develop in newborns for a variety of causes, including hereditary proclivities, infection, metabolic issues, diabetes, trauma, inflammation, or pharmacological responses. Tetracycline antibiotics, for example, have been found to induce cataracts in newborn kids when used to treat infections in pregnant women.

Congenital cataracts can also arise if the mother contracts an illness during pregnancy, such as measles or rubella (the most frequent cause), rubeola, chicken pox, cytomegalovirus, herpes simplex, herpes zoster, poliomyelitis, influenza, Epstein-Barr virus, syphilis, or toxoplasmosis.

For similar reasons, older newborns and toddlers can be diagnosed with cataracts, known as pediatric cataracts. However, in 40% of cases of cataracts in older children, trauma linked with events such as a blow to the eye is the underlying reason.

Furthermore, some pediatric cataracts may be congenital cataracts that were simply missed earlier because the kid did not have his or her first eye test until the child was older.

Treatment of congenital cataracts

Cataract surgery is the sole therapy for congenital cataracts. If your kid has congenital cataracts that are severe enough to necessitate treatment, consult with a pediatric cataract specialist who specializes in congenital cataract surgery.

The only way to know for certain if your young kid's eyes are healthy and developing properly is to arrange an early childhood eye test for your child when he or she is 6 months old.

 

Does My Child Need Cataract Surgery?

When surgery should be performed on a child with congenital cataracts is debatable. Some specialists believe that between the ages of 6 weeks and 3 months is the best time to treat and remove a visually significant congenital cataract. If your infant has a congenital cataract, talk to your eye doctor about any concerns you have regarding the timing of cataract surgery.

Once the cataract has been removed, your child's vision must be restored with a surgically implanted intraocular lens (IOL), contact lens, or eyeglasses. Without vision correction after cataract surgery, the eye will have impaired vision, preventing normal baby vision development.

Opinions differ on whether an artificial lens should be surgically implanted in a baby's eye following cataract surgery due to concerns that normal eye growth and development may be hampered. Because of probable vision changes, an IOL may also need to be removed and swapped as your kid grows.

Contact lenses placed to the surface of the eye (cornea) may be used in some circumstances to assist restore vision after the natural lens is removed during cataract surgery. In addition, eyeglasses may be recommended to improve eyesight instead of an implanted artificial lens or contact lens.

If the eye surgeon recommends contact lenses following congenital cataract surgery, extended wear contacts are often recommended to make contact lens maintenance and handling easier.

Your eye doctor or a member of his or her staff will teach you how to apply and remove your child's contacts. This is often possible while your newborn or very young child is sleeping.

 

Inherited strabismus

Strabismus is characterized as an intermittent or continuous misalignment of the visual axis of the eyes, which interferes with binocular single vision. The most prevalent kind of misalignment is horizontal, but vertical and oblique abnormalities are sometimes seen. The divergence may be latent, due to fusional processes, or evident in one, many, or all fields of sight. Strabismus caused by traumatic paralysis or damage to the extraocular muscles will not be examined because it is clearly acquired.

 

When do the symptoms of strabismus appear?

An infant's eyes should be able to focus on small objects and be straight and well-aligned by the age of 3 to 4 months. A 6-month-old child should be able to focus on objects both close and far away.

Strabismus commonly emerges in newborns and young children, and it is most common by the age of three. Strabismus can, however, develop in older children and even adults. In an older child or adult, the abrupt occurrence of strabismus, particularly with double vision, might suggest a more serious neurologic condition. If this occurs, contact your doctor right away.

A disorder known as pseudostrabismus (false strabismus) can cause a baby's eyes to seem crossed when they are actually pointing in the same direction. Extra skin covering the inner corners of the eyes and/or a flat nasal bridge can induce pseudostrabismus. The eyes will no longer seem crossed as the baby's face matures and expands.

 

How is strabismus diagnosed?

Anyone over the age of four months who looks to have strabismus should have a thorough eye examination by a pediatric ophthalmologist, with special attention paid to how the eyes focus and move. The following items may be included in the exam:

• Patient history (to determine the symptoms the patient is having, family history, general health problems, medications being used and any other possible causes of symptoms)
• Visual acuity (reading letters from an eye chart, or examining young children’s visual behavior)
• Refraction (checking the eyes with a series of corrective lenses to measure how they focus light). Children do not have to be old enough to give verbal feedback when checking for glasses.
• Alignment and focus tests
• Examination after dilation (widening) of the pupils to determine the health of internal eye structures

 

How is strabismus treated?

Treatment options include the following:

• In individuals with untreated refractive errors, eyeglasses or contact lenses are used. Corrective lenses need less concentrating effort and allow the eyes to remain straight.
• Prism lenses: These are special lenses that can bend light entering the eye, reducing the amount of twisting the eye needs perform to look at objects.
• Orthoptics (eye exercises): These can help with some kinds of strabismus, particularly convergence insufficiency (a form of exotropia).
• Medications include eye drops and ointments. In addition, botulinum toxin type A injections (such as Botox) might weaken an overactive eye muscle. Depending on the patient's circumstances, these therapies may be utilized in addition to or instead of surgery.
• Patching: To cure amblyopia (lazy eye) if the patient has it together with strabismus. Control of eye misalignment may improve as vision improves.
• Eye muscle surgery: Surgery alters the length or location of the eye muscles, allowing the eyes to be properly aligned. This is done with general anesthesia and dissolvable sutures. Adults are occasionally provided adjustable strabismus surgery, in which the eye muscle locations are modified following surgery.

 

Retinitis Pigmentosa

Retinitis pigmentosa (RP) is a set of retinal eye diseases. This disorder alters the way the retina responds to light, making it difficult to see. RP is a hereditary disorder, which means it may be handed down through generations. The kind and rate of visual loss caused by RP differs from person to person. It is determined by the severity of their disease.

 

Retinitis Pigmentosa Symptoms

With RP, you may have vision loss in the following ways:

• Loss of night vision. Night blindness occurs when you are unable to see anything in the dark. During the day, your eyesight may be normal. It takes longer to acclimate to darkness when you lose your night vision. You may trip over things or have difficulty driving at dark and at night. You may also have difficulty seeing in darkened spaces such as movie theaters.
• Gradual loss of peripheral (side) vision. This is referred to as "tunnel vision." You can run into items as you travel about. This is due to your inability to perceive items underneath and around you.
• Loss of central vision. Some people may have issues with their center vision. This might make it difficult to do intricate tasks like reading or threading a needle.
• Problems with color vision. Some people may also have trouble seeing different colors.

 

How Is Retinitis Pigmentosa Diagnosed?

RP can be diagnosed and measured by:

• Genetic analysis. This test examines a sample of your blood or other tissues to determine whether you have particular genes that are linked to a disease. It can also assist predict the course or severity of a disease, as well as if gene therapy to replace the defective gene might be beneficial.
• Electroretinography. The electrical activity in the retina, or how well the retina responds to light, is measured in this test. It functions similarly to an EKG, which evaluates the activity and health of the heart.
• Visual field evaluation. Your peripheral (side) vision may be affected by RP. Visual field testing measures your side vision and detects any growing blind spots.
• Optical coherence tomography. This imaging test, also known as OCT, takes specific, very detailed photographs of your retina. It can help diagnose RP and determine how it affects your retina.

 

Can Retinitis Pigmentosa Be Treated?

There is no one therapy for RP because it is caused by over 100 genes. Scientists are investigating why and how RP occurs among families. They want to use this knowledge to build remedies.

Although some evidence suggests that vitamin A may reduce the evolution of certain kinds of RP, there is worry that excessive use of these supplements may aggravate other eye diseases. Your ophthalmologist can advise you on the dangers and advantages of vitamin A, as well as the appropriate dosage. Too much vitamin A can be dangerous, and there is little evidence of its influence on RP development. As a result, vitamin A supplements are not currently advised.

Some people experience retinal edema and may benefit from an eye drop or medicine administered orally. Cataracts, or clouding of the lens of the eye, may also occur, and surgery to cure this may be beneficial for certain people.

One kind of RP caused by a mutation in the RPE65 gene is currently treatable with medication. This medication is administered beneath the retina during vitrectomy surgery. Scientists are working hard to discover genetic cures for various types of RP, so knowing what exact genetic flaw causes your RP is critical.

People with poor eyesight can learn to maximize their remaining vision. There are several instruments and other methods for doing jobs. These tools and approaches can be taught to you by vision specialists.

If you have RP and want to have children, talk to a genetic counselor about your chances of passing on this eye issue to your offspring.

 

Keratoconus

The transparent, dome-shaped window at the front of your eye is known as the cornea. It directs light into your eyes. Keratoconus is a condition in which the cornea thins and bulges in the shape of a cone. Light rays get out of focus as the shape of the cornea changes. As a result, your vision becomes fuzzy and distorted, making everyday tasks such as reading or driving difficult.

 

What Causes Keratoconus?

Doctors are unsure why people get keratoconus. It appears to be hereditary in certain situations (passed down in families). One in every ten persons with keratoconus has a parent who also has it. Keratoconus is also linked to:

• Eye allergies
• excessive eye rubbing, and
• connective tissue disorders like Marfan syndrome and Ehlers-Danlos syndrome

 

Keratoconus Symptoms

Keratoconus is most common in persons in their late teens to early twenties. Over a period of 10 to 20 years, the eyesight issues gradually worsen. Keratoconus frequently affects both eyes and might result in extremely different vision between the two. Symptoms might differ between eyes and alter over time.

In the early stage, keratoconus symptoms can include:

• Mild blurring of vision
• Slightly distorted vision, where straight lines look bent or wavy
• Increased sensitivity to light and glare
• Eye redness or swelling
  

In later stages, keratoconus symptoms often include:

• More blurry and distorted vision
• Increased nearsightedness or astigmatism (when your eye cannot focus as well as it should). As a result, you may need new eyeglass prescriptions often.
• Not being able to wear contact lenses. They may no longer fit properly and they are uncomfortable.

Keratoconus often progresses over years from the early to late stages. Keratoconus, on the other hand, might worsen swiftly in certain people. The cornea might abruptly enlarge and scar. Scar tissue causes the cornea to lose its smoothness and clarity. As a result, eyesight becomes increasingly distorted and hazy.

 

Keratoconus Diagnosis

Keratoconus is detectable during a standard eye checkup. Your ophthalmologist will inspect and maybe measure the curvature of your cornea. This aids in determining whether or not its form has changed. Your ophthalmologist may also use a sophisticated computer to map the surface of your cornea. This detailed picture depicts the surface of the cornea.

How is Keratoconus Treated?

Keratoconus therapy is determined by your symptoms. When your symptoms are minimal, you can fix your eyesight using glasses. Later on, you may need to wear hard contact lenses to assist keep your vision in focus. Your ophthalmologist may also treat keratoconus in the following ways:

• Intacs. This is a little curved device that is surgically implanted in your cornea by your ophthalmologist. Intacs assist to enhance eyesight by flattening the curvature of your cornea.
• Cross-linking of collagen. To strengthen the cornea, your ophthalmologist will use a specific UV light and eye drops. This helps to flatten or harden your cornea, preventing it from bulging more farther.
• Corneal transplant. Your ophthalmologist may recommend a corneal transplant if your symptoms are severe. Your ophthalmologist replaces your damaged cornea with healthy donor cornea tissue.

 

Less Common Eye Disorders

Some genetic eye illnesses and ailments are less prevalent. Among them are the following:

• Achromatopsia: Achromatopsia impairs a person's central vision and color vision. The disorder is autosomal recessive, which means that an afflicted person receives a mutant copy of an achromatopsia-linked gene from both parents.
• Albinism: Albinism is a category of genetic illnesses in which the pigment melanin, which affects the color of the skin, hair, and eyes, is produced insufficiently or not at all. Although everyone has a possibility of producing a kid with albinism, some couples are more likely to pass it on if one or both parents have the albinism gene.
• Choroideremia: Choroideremia is a rare X-linked recessive type of hereditary retinal degeneration that impairs the retina's blood flow. This disorder affects around 1 in 50,000 boys and causes a slow loss of vision, beginning with childhood night blindness, proceeding to peripheral vision loss, and eventually leading to loss of central vision.
• Cone-rod dystrophy: Cone-rod dystrophy is a series of hereditary eye illnesses that cause the cones and rods, which are light-sensitive cells in the retina, to deteriorate. People with this illness gradually lose their vision. Initial indications and symptoms that often appear in infancy include diminished vision sharpness (visual acuity) and aberrant light sensitivity (photophobia).
• Corneal dystrophies: Corneal dystrophies are a type of hereditary eye condition in which aberrant material frequently accumulates in the clear (transparent) outer layer of the eye (cornea). The corneas lose their clarity and become clouded as a result of this hereditary disorder, causing considerable visual impairment.

 

Treating Hereditary Eye Diseases

There are several therapies available for the various forms of inherited eye disease. Before treatment begins, you will be given a complete eye exam, and your medical and genetic histories will be taken into account.

Some moderate kinds of eye illness might not require treatment, whilst others require eye patches, prescription glasses, or medication. Surgery may be required in some circumstances to enhance eyesight or to avoid significant consequences.

 

Conclusion 

Many forms of eye illness can be passed down via families. The majority of baby blindness instances are caused by hereditary eye illnesses such as glaucoma, cataracts, retinal degeneration, and eye abnormalities. In addition, inheritable glaucoma and macular degeneration are two of the primary causes of adult blindness.