Leber Congenital Amaurosis (LCA) is a family of congenital retinal dystrophies that results in severe vision loss at an early age leading to blindness by the age of one.  Various phenotypes (LCA1 to LCA19) with at least 29 genotypes have been identified in around 70-80% of cases of LCA. Dystrophy is a heterogeneous recessive disease and is estimated to affect 1 in 30,000- 81,000 individuals.

Key Takeaways

• Leber Congenital Amaurosis (LCA) is a congenital retinal dystrophy resulting in nystagmus and significantly reduced vision.
• Franceschetti’s oculo-digital sign is characteristic of LCA.
• Luxturna, a gene therapy drug, was approved by the FDA in 2017 for LCA patients with a RPE65 mutation. 

Understanding Leber Congenital Amaurosis

Leber Congenital Amaurosis (LCA) is also known as congenital retinitis pigmentosa (RP). Significant visual impairment and nystagmus is usually present from birth in individuals with LCA. One-third of those with LCA have no perception of light. In the early stages, a mild degree of visual improvement can be observed, but may be followed by progressive degradation. It is suggested that LCA is a degenerative process involving the outer retina and photoreceptors. LCA accounts for almost 5% of all retinal dystrophies, and 20% of children with visual impairment in special schools. Cataracts, keratoconus, and oculodigital reflex (eye rubbing or poking) are commonly associated with LCA. 

Franceschetti’s oculo-digital sign is characteristic of LCA. This sign consists of affected individuals poking, pressing, and rubbing their eyes with a knuckle or finger. Poking their eyes often results in the sensation of flashes of light called phosphenes. Studies suggest this behavior contributes to deep-set eyes in children with the dystrophy.

Risk Factors for Leber Congenital Amaurosis

The risk factor for LCA is an affected parent and/or parents who are carriers of a mutated gene responsible for one of the 17 LCA subtypes. Genes with known mutations are GUCY2D, RPE65, SPATA7, AIPL1, LCA5, RPGRIP1, CRX, CRB1, NMNAT1, CEP290, IMPDH1, RD3, RDH12, LRAT, TULP1, KCNJ13, GDF6, CABP4, CNGA3, ALMS1, IQCB1, and MYO7A. The other genes causing LCA are unknown. CEP290 (15%), GUCY2D (12%), and CRB1 (10%) and RPE65 (8%) are the most frequently mutated LCA genes.

Leber Congenital Amaurosis Symptoms

The symptoms of Leber Congenital Amaurosis may include:

• Nystagmus
• Sluggish or near-absent pupillary responses
• Decreased vision in infancy (20/200 to complete blindness)
• Photophobia
• High hyperopia (>5 diopters)
• Keratoconus
• Nyctalopia

Diagnosing Leber Congenital Amaurosis

When a doctor views the retina in these individuals, it initially appears normal. Over time, a variety of abnormalities may develop.  These findings may include chorioretinal degeneration and atrophy centered around the fovea, “bone-spicule” like pigmentation, subretinal flecks, “marbled” fundus, pigmented nummular lesions at the level of the retinal pigment epithelium (RPE), optic disc abnormalities, and a “Coats like” reaction. In advanced cases of LCA, retinal arterioles are attenuated reflecting the metabolic status of the retina. Though rare, LCA may be seen in association with neurodevelopmental delay, intellectual disability, and oculomotor apraxia-type behavior.

Advanced testing can be used to confirm diagnosis. A non-recordable/extinguished or severely reduced scotopic and photopic electroretinogram (ERG) is typical in LCA. Normal ERG responses rule out a diagnosis of LCA. Visual evoked responses are variable. Autofluorescence can measure lipofuscin accumulation in RPE which is related to shed photoreceptor disc elements. The amount of autofluorescence in LCA varies by subtype; autofluorescence is normal in GUCY2D mutation but absent in RPE65 mutations. OCT can be used to see retinal atrophy which is common in LCA. Visual fields can be detectable in some patients, but these are small central islands and on occasion, peripheral islands with the largest and brightest target. Genetic testing may also help with the diagnosis.

Leber Congenital Amaurosis Treatment

There is no treatment or cure for most gene types of LCA. Individuals with the dystrophy can benefit from refractive error correction (glasses or contact) and low-vision aids. There are several ongoing clinical trials for treating LCA, including gene replacement therapy or photo pigment supplementation.

In 2017, The FDA approved voretigene neparvovec-rzyl (Luxturna), an adeno-associated virus vector-based gene therapy drug for treating patients with confirmed biallelic RPE65 mutation-associated LCA.

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Corneal refractive therapy (CRT) corrects myopia (nearsightedness) by sleeping in special contact lenses overnight. They are worn before bedtime and removed when waking up in the morning, and improve daytime vision in nearsighted people. They work by changing the curvature of the cornea, the front of the eye, while asleep. The lenses are a good option for children and adults who have an active lifestyle or want to be lens-free during the day. 

CRT lenses may also control the progression of nearsightedness in children. A child with rapidly increasing nearsightedness can use CRT lenses to slow down the progression of nearsightedness. High myopia (nearsightedness of -6.00 DS or greater) can lead to problems such as retinal detachment and glaucoma in adulthood. CRT lenses may minimize the risks of a child developing high myopia. 

Key Takeaways

• Corneal refractive therapy (CRT) lenses are hard contact lenses that reshape the eyes while sleeping, allowing one to see clearly without glasses or contact lenses during the daytime.
• The effect of CRT lenses is temporary, so the lenses must be worn every night to maintain sharp vision.
• CRT lenses are typically used for people who play sports, or to manage the progression of myopia (nearsightedness) in children. 

Understanding Corneal Refractive Therapy

Corneal refractive therapy (CRT) is the process of using special hard contact lenses that are designed to reshape the eye overnight. CRT is also known as OrthoKeratology (Ortho-K). CRT uses gas-permeable contact lenses that are worn overnight and removed in the morning. The material of the CRT lenses is highly oxygen permeable and thus approved for overnight wear. CRT lenses correct the nearsighted prescription overnight. They work by gently and gradually reshaping the cornea, the front surface of the eye. People who wear CRT lenses overnight have clear vision during the day without glasses or contact lenses.

CRT lenses or Ortho-K lenses only temporarily correct the vision. Their effect lasts for 24 to 72 hours after the lenses are removed. It takes around two weeks after starting CRT lenses to fully correct the prescription. The contact lenses can correct moderate nearsightedness (myopia) up to -6.00 diopters and astigmatism up to -1.75 diopters. 

Why Choose Corneal Refractive Therapy? 

The basic goal of corneal refractive therapy (CRT) is to avoid using contact lenses or glasses when awake. People who typically benefit from CRT include:

• Children and adults who do sports, such as swimming, or have active lifestyles 
• People working in dusty or dirty environments
• Children with rapidly increasing nearsightedness (myopia)
• Children whose parents have high nearsighted prescriptions
• Anyone who prefers to be contact lens-free or glasses-free during the daytime

Downsides of Corneal Refractive Therapy

The downsides of corneal refractive therapy (CRT) include: 

• Initial discomfort or eye pain when trying rigid gas-permeable lenses 
• Experiencing blurry vision for the first two weeks of CRT wear
• Slightly higher rate of eye infections compared to daytime soft contact lenses
• Slower rate of natural healing of the eyes after extended overnight wear 

Corneal Refractive Therapy Procedure 

1. The eye doctor will fit a contact lens onto your eye and ensure that it fits the unique shape of your eyes. Some lens parameters may need to be adjusted, so they might need to try a few different options. 
2. After finding a close match, the eye doctor will instruct you on how to insert and remove the contact lenses. Since most people have not used hard gas permeable lenses before, they usually experience moderate discomfort when the lenses are first tried. The eye should gradually get used to the hard lens material over the course of two weeks. 
3. Once you are able to safely and comfortably insert and remove the contact lenses, you will be allowed to take them home. 
4. You should put the lenses onto your eyes approximately ten minutes before you sleep. 
5. You will remove the lenses as soon as you wake up in the morning. 
6. People usually experience great eyesight within a few days. Most people will reach their ideal vision within 10-14 days.
7. The eye doctor will schedule regular follow-up appointments, typically every 3 months, to make sure the contact lenses are still fitting well.

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Argyll Robertson pupil is a condition that affects the pupils. The pupil is the circular black spot in the center of the eye. People with Argyll Robertson pupil have very small pupils that do not react to bright light. This eye condition is usually caused by syphilis, a sexually transmitted disease. Advanced stages of syphilis affect the nervous system and the eyes. It may cause symptoms such as light sensitivity, loss of balance, or tingling toes. The treatment for Argyll Robertson pupil consists of treating the underlying syphilis with antibiotics, which can be given intravenously or intramuscularly. 

Key Takeaways

• Argyll Robertson pupil is a condition in which the pupils are small and cannot respond to bright light. 
• It is most commonly caused by syphilis, a sexually transmitted disease. 
• Argyll Robertson pupil is treated with antibiotics directed towards the underlying syphilis infection.

Understanding Argyll Robertson Pupil

The pupil allows light to enter the eye. It looks like a black circle on the front of the eye. Normal pupils become larger and ‘dilate’ in the dark to allow more light to enter. Normal pupils get smaller, or ‘constrict’, when light is shined into them. The pupils should also naturally shrink when looking at near objects, such as when reading. 

People with Argyll Robertson pupil have abnormal pupillary reactions. They have small pupils which do not dilate in the dark. Their pupils do not constrict when bright light is shined into them. However, their pupils still have a normal response (constriction) when looking at near objects. Argyll Robertson pupil is a sign of late-stage syphilis, known as neurosyphilis. 

Causes

The most common cause of the Argyll Robertson pupil is late stage syphilis. Syphilis is a sexually transmitted disease caused by infection with Treponema pallidum bacteria.

The first stage of syphilis involves developing sores, which are skin lesions known as chancres. The painless sores may develop around the mouth, lips, or genitals. Next, a rash may develop on the hands or feet. Syphilis can also cause no symptoms. It’s possible for syphilis to spread throughout the body for years undetected. If untreated, syphilis can become tertiary syphilis or ‘neurosyphilis’. Neurosyphilis is a late-stage infection that causes damage to the organs and nervous system, including the eyes. Once syphilis spreads to the eyes, it can cause Argyll Robertson pupil.

Pathophysiology

Our pupils constrict, or shrink in response to light, due to the efferent pupillary pathway. Light signals enter the eye, strike the retina, and are transmitted to the brain through the optic nerve. The optic nerve carries the light signal to the pretectal area in the midbrain. Then, the light response is sent from the pretectal area to the Edinger Westphal nucleus in the midbrain. Argyll Robertson pupil results from damage to the Edinger Westphal tissue in the midbrain. When this area of the brain is damaged, the pupils fail to react to bright light. 

Diagnosis

Diagnosis of Argyll Robertson pupil is made during an eye examination. An eye doctor will shine a bright light into the eyes to check if the pupils are responding normally. The eyes may be dilated in order to make the pupils larger and examine the health of the retina. 

Signs of Argyll Robertson pupil include:

• Small ‘pinpoint’ pupils in both eyes
• The pupils do not constrict when light is shined into them
• The pupils do not dilate in the dark
• The pupils constrict when reading or looking at near objects

Syphilis can affect the eyes in many different ways, besides causing Argyll Robertson pupil. Eye symptoms of syphilis include:

• Red eyes
• Light sensitivity
• Eyelid swelling
• Eye pain
• Headache
• Blurry vision

If an Argyll Robertson pupil is diagnosed, a blood test may be ordered to check for syphilis. Examples of these blood tests include IgG, RPR or VDRL, and FTA-ABS or TP-PA. These tests will detect whether there is an active syphilis infection in the body. 

Treatment

If laboratory blood tests are positive for syphilis, then treatment should be started promptly. Argyll Robertson Pupil and neurosyphilis are treated with antibiotics. Penicillin is the most common antibiotic of choice. Alternatively, doxycycline or ceftriaxone may be used if the person is allergic to penicillin. The antibiotics may be delivered intravenously or intramuscularly for 10 to 14 days.

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The medial rectus is one of seven extraocular muscles of the eye. The extraocular skeletal muscles of the eye include four rectus muscles, two oblique muscles, and the levator palpebrae superioris. The medial rectus is one of the four rectus muscles. The medial rectus muscle is the largest of the extraocular muscles and its size is likely from frequency of use in convergence.

The medial rectus is an adductor and works together with the lateral rectus which abducts the eye.  The medial rectus pulls the eye towards the nose while the lateral rectus moves the eye toward the ear. These two muscles enable the eyes to move side to side. When the head is facing straight and the eyes are facing straight ahead, the eyes are in primary gaze. From this position, an extraocular muscle’s action produces a secondary or tertiary action. 

Key Takeaways

• The medial rectus is one of seven extraocular muscles.
• The medial rectus is an adductor and pulls the eye towards the nose.
• The medial rectus can be affected in strabismus and in thyroid eye disease.

Understanding the Medial Rectus Muscle

The primary blood supply for all the extraocular muscles is the ophthalmic artery. The medial rectus is innervated by the lower division of cranial nerve III (oculomotor). Each of the rectus muscles originate from behind at the Annulus of Zinn and courses towards the front. The medial rectus runs along the medial orbital wall. Each rectus muscle inserts on the globe at varying distances from the limbus; the medial rectus inserts at 5.5 mm from the limbus and is 10.3 mm wide at its insertion on the globe. 

Conditions Affecting the Medial Rectus Muscle

Weakness, injury, or paralysis that involves the medial rectus muscle can lead to strabismus. Medial rectus muscle restriction or compression may cause incomitant esotropia. Several conditions may cause this such as thyroid myopathy, medial orbital wall fracture, Duane syndrome, or post-surgical excessively resected medial rectus muscle.

Changes in the medial rectus muscle can also be used to detect progressive thyroid disease. In fact, imaging of the medial rectus muscle can be used to predict the development of optic neuropathy in thyroid eye disease.

Medial Rectus Muscle Diagnosis

The function of the medial rectus muscle is evaluated by an eye care provider during an eye exam. Extraocular muscle movement can be assessed by having the patient look in nine directions. Assessment begins in primary gaze, followed by the secondary positions (up, down, left, and right) and the tertiary positions (up and right, up and left, down and right, down and left). The clinician tests these positions by having the patient follow the clinician’s finger as it traces a wide letter “H” in the air. Further testing of the extraocular muscles includes cover tests, corneal light reflex, dissimilar image tests, and dissimilar target tests. 

Medial Rectus Muscle Surgery

Surgery for strabismus may involve the medial rectus muscle. Recession of the medial rectus is a measured retroplacement of the muscle from its original insertion site. It is the easiest and most effective way to weaken the medial rectus. Resection is removing a part of the medial rectus and reattaching it at its original insertion site, which effectively strengthens the action of the muscle. Unsatisfactory muscle alignment is common and may require additional surgeries. Refractive changes may occur when two rectus muscles of one eye are operated on. 

Damage to the medial rectus muscle is possible during surgery, but unlikely. However, blood vessels may be compromised during surgery of the medial rectus. The vessels that supply blood to the medial rectus also supply almost all of the temporal half of the anterior segment of the eye. Care must be taken by the surgeon to avoid disrupting the blood supply. 

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The lacrimal punctum is a small aperture located in the slightly elevated eyelid tissue called the lacrimal papilla, at the junction of the lacrimal and ciliary portions of the eyelid margin. A punctum can be found in both the upper and lower lids. The puncta are turned inward toward the globe and can be seen only if the eyelid edge is everted slightly outward. Each punctum opens into a tube, called the lacrimal canaliculus that joins the puncta with the lacrimal sac. 

Key Takeaways

• Puncta play an important role in tear drainage.
• Puncta can be occluded to treat dry eye disease.
• Punctal occlusion may improve dry eye symptoms.

Understanding the Puncta

Tears produced by the lacrimal system move medially with lid blinking. They flow through the lacrimal punctum in each eyelid margin and through the superior and inferior canaliculi in the medial aspect of the upper and lower eyelids. They then drain via the sinus of Maier into the lacrimal sac. The lid acts like a windshield wiper, pushing the tears into the puncta to be removed from the eye.

Occlusion Treatment of the Puncta

Punctal occlusion is a mechanical treatment in which the tear drainage system is blocked to preserve the natural tears on the ocular surface. Punctal occlusion is often used when artificial tears do not improve the patient’s dry eye symptoms. By occluding the puncta, the eye doctor preserves the tears, which improves aqueous tear film quality and quantity.

Semi-permanent silicone or temporary collagen punctal plugs are inserted into the upper or lower puncta or both. Collagen plugs dissolve within four to seven days while silicone plugs either come out spontaneously or are removed by a physician. Permanent occlusion of the puncta is achieved by thermal cautery or argon laser.

 Studies show that with punctal occlusion treatment, patient symptoms improve in 74% of eyes at four weeks with a significant reduction in fluorescein staining and use of adjunctive lubrication in the same time period. Patients also report improved contact lens comfort and wearing time after punctal occlusion.

Adverse outcomes of punctal occlusion may include epiphora (overflow of tears), foreign body sensation, eye irritation, and spontaneous plug loss. 

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A rhegmatogenous retinal detachment (RRD) is the most common retina emergency with an incidence of 1 in 10,000 individuals per year. RRD occurs when a retinal tear or hole allows fluid to accumulate below the retinal surface, causing the retina to separate from the underlying layers. A retinal detachment is a separation of the neurosensory retina from the retinal pigment epithelium and can lead to vision loss. 

Key Takeaways

• Rhegmatogenous retinal detachments are a serious ocular emergency.
• A sudden onset of floaters, flashes of light, or a curtain may indicate a rhegmatogenous detachment.
• Scleral buckles, vitrectomy, and pneumatic retinopexy are treatments for rhegmatogenous detachments.

Understanding Rhegmatogenous Retinal Detachments

Rhegmatogenous retinal detachments (RRD) are caused by the passage and collection of fluid into the retina through a hole or tear. The fluid builds up and causes the retina to pull away from underlying tissues resulting in the loss of the blood supply. RRD can result in a deterioration of one’s peripheral vision and central vision when it involves the macula. Rapid reattachment is required to prevent the eye from further photoreceptor damage and visual loss.

Tractional and exudative are the other two types of retinal detachments. Tractional detachments occur when scar tissue, typically from diabetic retinopathy, grows on the retinal surface causing the retina to pull away from the back of the eye. In an exudative detachment, there are no holes or tears, but fluid accumulates beneath the eye. An exudative detachment may be caused by age-related macular degeneration (ARMD), injury, tumors, or inflammatory disorders.

Risk Factors for Rhegmatogenous Retinal Detachments

Myopia (near-sightedness) and prior cataract surgery are the main risk factors for an RRD. Those in the sixth and seventh decades of life are most affected. It affects men more than women, and white people more than black people.  Patients with a history of trauma, eye surgery, eye injury or previous retinal detachment are at an increased risk. Other eye diseases or disorders, including retinoschisis, uveitis and lattice degeneration (retinal thinning) may put a patient at risk.

Rhegmatogenous Retinal Detachment Symptoms

The symptoms of rhegmatogenous retinal detachment include:

• The sudden appearance of many floaters 
• Flashes of light 
• Blurred vision
• Gradually reduced side (peripheral) vision
• A curtain-like shadow over the field of vision

Diagnosing Rhegmatogenous Retinal Detachments

A rhegmatogenous retinal detachment is diagnosed by an eye doctor during a dilated eye exam. 

Rhegmatogenous Retinal Detachment Treatment

The treatment for a rhegmatogenous retinal detachment (RRD) consists of a scleral buckle, removal of the vitreous body (vitrectomy), or a combination of both. Scleral buckle (SB) is the use of a silicone band placed around the eye to reduce traction on the retina caused by the vitreous humor that fills the eye. Pars plana vitrectomy (PPV) eliminates traction on the retina by removing the vitreous, and a pneumatic retinopexy (PR) is used to reattach the retina by holding it back into place with an expanding gas bubble. However, no consensus has been reached on which approach is ideal.

Success rates for RRD repair are in the range of 85% to 90%; however, vitrectomy results in cataracts in more than 70% of cases. The earlier the patient is seen by an ophthalmologist, the greater the chance that the macula is still attached, so vision can be preserved. ’Macula-on’ detachments where the fovea is still attached have a better prognosis. ‘Macula-off’ retinal detachments have a worse prognosis even with successful reattachment of the retina.

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Ocular Toxocariasis is a rare infection from common roundworms Toxocara canis and Toxocara cati. It typically affects children and can lead to a significant loss of vision despite medical and surgical therapies. Toxocara canis and Toxocara cati are among the most widely distributed helminthic species in the world with a high zoonotic impact. Millions of people have been infected and hundreds of thousands are suffering from toxocariasis. 

The disease has two major categorizations: visceral larva migrans (VLM) and ocular larva migrans (OLM). Toxocara antibody levels in the United States are estimated at 13.9%, but symptomatic infections are significantly less common, especially OLM.

Key Takeaways

• Ocular Toxocariasis is an infection caused by roundworms that results in unilateral vision loss.
• The roundworms live in dog and cat intestines and contact leads to infection.
• Proper hygiene and public awareness are key to prevention.

Understanding Toxocariasis

Toxocariasis can be found worldwide. The nematodes live and mature in dog or cat intestines. As a mature adult, the organism releases eggs which are passed in the stool. Human contact with infected materials leads to human infection. The clinical course in humans varies from asymptomatic infection to severe organ injury and depends on the parasite load, the sites of larval migration, and the host’s inflammatory response.

The clinical presentation can be classified into one of four forms:

1. Posterior pole granuloma
2. Peripheral granuloma
3. Nematode endophthalmitis
4. Atypical presentation

Risk Factors for Toxocariasis

Geophagia (deliberate consumption of earth, soil, or clay) at a young age, playing in sandboxes, and exposure to and ownership of puppies and kittens are risk factors for Toxocariasis.  In puppies 2 to 6 months old, the prevalence of Toxocara Canis has been reported to be over 80%; however, in dogs older than one year this number drops to 20%. Water or food contaminated with the Toxocara eggs is another possible exposure.

Toxocariasis Symptoms

The symptoms of toxocariasis usually present unilaterally and include:

• Reduced vision
• Photophobia
• Floaters
• Leukocoria (white pupil)
• Pain

Diagnosing Toxocariasis

An eye doctor will take a comprehensive history and perform a dilated eye exam. In the back of one eye, they may view vitritis which is common in 90% of patients. If the infection is acute, Toxocara retinochoroiditis appears as a hazy, ill-defined white lesion with overlying vitritis. As it resolves, the lesion becomes a more distinct, demarcated, elevated white mass ranging from one-half to four-disc diameters in size. Atypical presentations may include inflammation and swelling of the optic nerve head, motile subretinal larvae, and diffuse chorioretinitis. Conjunctivitis, keratitis, iridocyclitis, focal iris nodules, and cataracts can also be observed. 

Toxocariasis Treatment

Management includes quieting the inflammation, eliminating the offending organism, and repairing vitreoretinal findings.  Blood work like an ELISA may be useful for ocular toxocariasis. Several imaging modalities are now used to visualize the manifestations of larvae and assist in the diagnosis and management of this infection.  

Medical therapy includes topical steroids to limit inflammation and prevent the development of tractional membranes and retinal detachments. Other options include periocular injections and oral corticosteroids at 0.5-1 mg/kg. In the case of anterior segment inflammation, cycloplegics are also used to prevent the formation of synechiae. The use of anti-parasitic therapy is unproven in the case of ocular toxocariasis. There is some support for the use of albendazole or thiabendazole to eradicate the organism. 

The CDC reports that approximately 25% of new cases of ocular toxocariasis require surgery. Vitrectomy is the most common surgery performed for ocular toxocariasis. Individuals may need surgery for persistent vitreous opacification, hemorrhage, tractional retinal detachment, and epiretinal membranes. 

Prevention of Toxocariasis

For the most part, the public is unaware of Toxocariasis. Increasing public awareness and reducing human exposure is the key to prevention. As the disease is more common in children, it’s important that they practice good hygiene, like handwashing after exposure to sandboxes, parks, and playgrounds. In adults, ingestion is most common, and an association has been found with eating raw meat especially raw cow liver.

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The vitreous body or vitreous humor is the clear, gelatinous extracellular matrix (ECM) structure that fills the posterior part of the eye. It is made of 40 ECMs and a list of non-ECM proteins, such as albumin, transferrin, and vitellogenin. The vitreous matrix is maintained with little changes throughout life. The gel of the vitreous body does undergo an age-dependent liquefaction which is a continuous loss of collagen IX and collagen II fibrils. The matrix network does not regenerate after vitrectomy.

Key Takeaways

• The vitreous body is a colorless, gelatinous material that fills the back of the eye.
• It provides nutrients, coordinates eye growth, and supports the retina.
• Vitreous detachments, vitreous hemorrhages, and syneresis can affect vision.

Understanding Vitreous Body

The vitreous body is a transparent, gel-like mass whose main component is water. It plays a role in providing nutrients to the lens, coordinates eye growth and provides support to the retina. It is located close to the retina and may be affected by retinal changes. 

Conditions Affecting the Vitreous Body

Vitreous hemorrhages, detachments, and syneresis may affect the vitreous body and decrease one’s vision clarity.

Vitreous Hemorrhage

A spontaneous vitreous hemorrhage can be serious and has a prevalence of 7 per 100,000 people per year. A vitreous hemorrhage is a bleed in the vitreous caused by pathologic mechanisms that disrupt normal retinal vessels, bleeding from diseased retinal vessels and abnormal new vessels, or extension of a hemorrhage through the retina. A hemorrhage into the vitreous body results in rapid clot formation and is followed by slow clearance of approximately 1% per day. A posterior vitreous hemorrhage may be the result of a retinal tear, diabetic retinopathy, vascular proliferation after retinal vein occlusion, age-related macular degeneration or Terson’s syndrome.

Posterior Vitreous Detachment

Posterior vitreous detachment (PVD) is defined as the separation of the posterior vitreous cortex from the inner limiting membrane of the retina. It is commonly associated with aging.  A PVD results from the vitreous gel becoming more liquid, which can place traction on the peripheral retina, resulting in rhegmatogenous detachments, pulling on the macula, optic disc, retinal blood vessels, and the creation of premacular membranes that contribute to macular pucker and holes. Posterior vitreous detachment is estimated to occur in two-thirds of those older than 65 years.

Vitreous Syneresis

Syneresis is the liquefaction of the vitreous body which may lead to a floater or PVD. The contraction occurs with age, but may occur with trauma or injury.

Symptoms of the Vitreous Body

An increase in the number of floaters and flashes of light may indicate changes in the vitreous body. Flashes and floaters can be symptoms of a retinal detachment and should be checked immediately by an eye doctor. 

Diagnosing Disorders of the Vitreous Body

A doctor may view changes to the vitreous during a dilated fundus examination. Fundus photography may pick up large changes to the vitreous body.

Vitreous Body Treatments

There are no treatments for changes in the vitreous humor resulting in floaters. A vitrectomy may be performed for a vitreous hemorrhage that does not clear and impedes vision. A vitrectomy is rarely performed for floaters resulting from posterior vitreous detachment or syneresis.

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Acrodermatitis enteropathica (AE) is a rare, autosomal recessive, inherited skin disorder associated with zinc deficiency in infants.  It is hypothesized that the absence of an enzyme, oligopeptidase, prevents zinc absorption. AE can present with several eye problems including conjunctivitis, blepharitis, corneal opacities, and photophobia. The prevalence of AE is estimated to be 1 to 9 in 1,000,000, with a global incidence rate of 1 in 500,000 newborns. The disease typically manifests during infancy at the time when infants are weaned from breast milk or earlier in infants that are formula-fed.

Key Takeaways

• Acrodermatitis enteropathica (AE) is an inherited, systemic disorder due to zinc deficiency.
• AE may result in many ocular and systemic complications or death if untreated.
• Lifelong zinc supplementation is a quick and effective treatment.

Understanding Acrodermatitis Enteropathica

Zinc plays a role in cellular processes and is an integral part of various metalloenzymes and transcription factors including nucleic acid and protein synthesis, wound healing, immune system function, and free-radical scavenging. Human breast milk is a major source of zinc, especially in the first 1 to 2 months of infancy. Additionally, a zinc-binding ligand in breast milk also increases the bioavailability of zinc in human breast milk which is absent in animal milk.

Infants may present with the classic triad of acrodermatitis enteropathica (AE): alopecia, diarrhea, and a periorificial and acral skin rash. If untreated, the condition can be fatal. Early diagnosis is key to preventing both ocular and systemic complications.

In the literature, there are cases of AE with ocular presentation including punctal stenosis, corneal changes, conjunctival xerosis, and moderate dry eye disease. Additional findings may include corneal scarring and loss of Bowman’s membrane, cataract formation, ciliary body atrophy, retinal degeneration, retinal pigment epithelium depigmentation, and optic atrophy.

Risk Factors for Acrodermatitis Enteropathica

Acrodermatitis enteropathica (AE) is an inherited form of zinc deficiency caused by a defect in zinc absorption. AE results from mutations in the zinc transporter gene SLC39A4 (solute carrier family 39 member A4), leading to improper intestinal zinc absorption. It is generally considered a disease of infancy and childhood, and its presentation at birth is unusual. No differences exist in prevalence between ethnicity and race.

Acrodermatitis Enteropathica Symptoms

Acrodermatitis enteropathica (AE) can present with a few symptoms including:

• Diarrhea
• Irritability
• Lethargy 
• Anorexia
• Growth retardation
• Anemia
• Amenorrhea
• Neuropsychiatric problems
• Perinatal morbidity
• Hypogonadism
• Hyposmia
• Hypogeusia 
• Immunological abnormalities 
• Eye abnormalities 

Diagnosing Acrodermatitis Enteropathica

Diagnosis is made based on clinical symptoms. Testing results of plasma zinc levels helps to confirm the diagnosis. A zinc level of less than 70 microgram/L in fasting or less than 65 microgram/dL in non-fasting individuals is diagnostic. 

 In some cases where a diagnosis is doubtful, a histopathological examination of the affected skin may be helpful but is not diagnostic alone. The characteristic changes include psoriasiform hyperplasia with necrolysis.

Acrodermatitis Enteropathica Treatment

The management of acrodermatitis enteropathica (AE) usually involves enteral or parenteral zinc supplementation. Lifelong supplementation with 3 mg/kg/day of elemental zinc may be required.  Shortly after beginning treatment, the clinical response is dramatic and occurs within a few days. The first sign of response to treatment is less irritability followed by improvement in skin lesions. Zinc levels should be continuously monitored.

In addition, genetic counseling is recommended for families with known cases of AE.

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Benign essential blepharospasm (BEB) is a type of focal cranial dystonia characterized by involuntary contractions of the orbicularis oculi muscle resulting in eye closure. Dystonia is a type of movement disorder and is characterized by either sustained or intermittent contraction of a muscle leading to abnormal repetitive movements or postures. Blepharospasm is a focal dystonia (focal means affects one body part) characterized by the simultaneous contraction of agonist and antagonist muscles, resulting in involuntary eyelid closure. 

The estimated prevalence of benign essential blepharospasm worldwide is 20 to 133 cases per million and varies by geographic area. Blepharospasm is less common than cervical dystonia in the United States and Europe. However, in Italy and Japan, blepharospasm is more common than cervical dystonia.

Key Takeaways

• Benign essential blepharospasm (BEB) is a focal cranial dystonia resulting in eyelid closure.
• Female gender and age over 50 increase your risk of BEB.
• Treatment may include surgery, pharmaceuticals, and Botox injections.

Understanding Benign Essential Blepharospasm

Patients with BEB have an increased blinking rate and an increased response in the R2 phase of the trigeminal blinking reflex (TBR). Basal ganglia dysfunction, overactivity of the seventh nerve leading to simultaneous forceful contractions of the eyelid protractors and retractors, ion channelopathy, and sensitization of the trigeminal system by photophobia are some proposed mechanisms of BEB. 

The spasm associated with blepharospasm tends to be synchronous and bilateral with variable symptoms. BEB symptoms can range from mild with increased blinking rate to functional blindness due to persistent muscle contraction. In many cases, the disease is progressive, initially presenting with contractions limited to the orbicularis oculi muscles and later extending to the musculature of the lower face and neck, which is known as Meige syndrome.

The etiology of blepharospasm is not well understood, but it is thought more than one factor must be present for the disease to occur. The two-hit hypothesis proposes that a predisposing factor and an environmental trigger must be present together for the disease to develop.

Risk Factors for Benign Essential Blepharospasm

Blepharospasm is more common in postmenopausal women. Women often present with a higher symptom frequency and severity. Incidence also increases with age and peaks between the ages of 50 to 70.

Risk factors may be genetic or non-inherited. Some gene mutations have been implicated in the development of the disease; 20% to 30% of cases have a positive family history. Other factors which are thought to cause BEB include neurotransmitter dysregulations, structural damage, and previous underlying eye disorders.

Many environmental risk factors are associated with an increased risk of developing BEB, including urbanization and working ‘white-collar’ jobs associated with a high-stress lifestyle. Reading, watching television, and computer screen use are thought to increase eye strain and may exacerbate BEB.  Lastly, 42.6% of patients experienced some sort of stressful life event before the onset of symptoms. 

Benign Essential Blepharospasm Symptoms

The primary symptom of BEB is involuntary muscle contractions and spasms of the eyelid muscles aggravated by fatigue or stress.

Diagnosing Benign Essential Blepharospasm

A comprehensive patient history can be helpful in determining the diagnosis. Patients with BEB will complain of bilateral, synchronous spasm of the orbicularis oculi muscle. These spasms may be brief repetitive blinking or a persistent closure of the eyes leading to visual impairment. 

There is a diagnostic algorithm that is based on the presence of bilateral, synchronous, and stereotyped movements of the orbicularis oculi muscle, the presence of a sensory trick, or increased blinking. This diagnostic algorithm has been shown to have a sensitivity of 93% and a specificity of 90% in differentiating BEB from other similar conditions.

Benign Essential Blepharospasm Treatment

Because the exact cause of BEB is not well understood, there is no definitive cure. Treatment options include photochromatic modulation, botulinum toxin injection, oral medications, and surgical management. Botox, a first line treatment for BEB, is periodically injected into the eyelid protractor muscles including the orbicularis oculi, corrugator supercilii, and procerus muscles. 

BEB is associated with dry eyes and photophobia, which should be treated accordingly. Psychiatric disorders, such as anxiety and depression, are associated with BEB and may require treatment.

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