Congenital Eye Disease

Overview

Congenital malformation can damage any portion of the eye and its surrounding tissues. Anomalies can occur alone, in groups, or as part of a systemic malformation syndrome. Early detection is critical for removing any impediments to visual development and identifying potential underlying multisystem disorders. Recognizing congenital eye defects can also help parents understand their children and provide genetic advice.

What is Congenital Eye Disease?

Congenital eye illnesses are caused by faulty eye development during pregnancy. While congenital eye problems can be caused by a gene mutation or exposure to drugs or alcohol during pregnancy, there is no known reason in many afflicted infants. Congenital eye diseases can affect any part of the eye and are frequently associated with

• Cloudiness of the front surface of the eye (cornea),
• Increased eye pressure (glaucoma),
• Irregularly shaped pupils, 
• Lens opacities (cataract), 
• Abnormalities of the light-detecting tissue in the back of the eye (retina), and
• Underdevelopment of the nerve that connects the eye to the brain (optic nerve.)

 Significant vision loss can occur in extreme situations when several eye structures are impacted.

Hypertelorism

Orbital hypertelorism is characterized as an increased distance between orbits with real lateral displacement. Anthropometric measures will show an increase in inner canthal distance (ICD), outer canthal distance (OCD), and interpupillary distance (IPD). True orbital hypertelorism is characterized by increases in all three measures beyond the 95th percentile on normative anthropometric values.

Hypertelorism Causes 

A change in embryological face development between weeks 4-8 of development is assumed to be the cause of hypertelorism. The frontonasal prominence is the embryological predecessor of the forehead and nose, and there is lateral movement of the orbits followed by medial migration during normal development of the frontonasal prominence. If the normal development of the frontonasal prominence is halted, the primitive brain fills the area, stopping the orbits from moving medially and arresting them in a lateral posture.

The presence of a Frank encephalocele or other masses in the frontonasal prominence might result in an evident and severe type of hypertelorism. Other hypothesized mechanisms of hypertelorism include early ossification of the sphenoid bone's lesser wings, which prevents medial movement of the orbits and fixes them in the fetal position, and craniosynostosis syndromes, which result in premature closure of cranial sutures, which prevents normal orbital migration and development. 

Hypertelorism is produced by the protrusion of the cribriform plate of the ethmoid bone in Apert syndrome, one of the most frequent craniosynostosis syndromes, disrupting cranial base development.

Hypertelorism symptoms

Isolated hypertelorism is uncommon. As a result, it is critical to assess a patient with hypertelorism for additional physical exam abnormalities. Hypertelorism is often detected at birth, and in some cases even before birth as fetal ultrasound technology improves. Hypertelorism combined with medial clefting of the face and/or nasal capsule dysplasia is more likely to be linked with other congenital defects. 

Hypertelorism in the presence of craniofacial synostosis can be syndromic or nonsyndromic. Apert syndrome is distinguished by a sunken midface, a beaked nose, tooth crowding secondary to an undeveloped maxilla, visual issues secondary to shallow eye sockets, mild to severe intellectual handicap, syndactyly or polydactyly, hyperhidrosis, and cleft palate.

Carpenter syndrome is characterized by a cloverleaf skull shape, low set ears, aberrant dentition, syndactyly or polydactyly, intellectual handicap, umbilical hernia, obesity, congenital heart disease, hip and spine deformities, and genital abnormalities. Crouzon syndrome can be distinguished by midface hypoplasia, a beaked nose, dental anomalies, hearing loss, and normal IQ.

Finally, the physical exam varies depending on the underlying cause of hypertelorism. When hypertelorism is detected as a physical finding, a comprehensive head to toe physical exam is required to rule out any dysmorphic characteristics or congenital anomalies.

Hypertelorism Diagnosis 

The assessment of hypertelorism necessitates particular and exact measures. Although radiograph or computed tomography measures of bony inter-orbital space are the most precise and crucial for surgical planning, they are unsuitable for the initial diagnosis of a patient with suspected hypertelorism.

Proper measuring method includes having the patient sit comfortably on a chair in front of the examiner, with the patient's head at the same level as the examiner's head, gazing straight ahead. On the nasal bridge, a little plastic translucent ruler measuring to the closest millimeter is put. The distances between the inner and outer canthi, as well as the palpebral fissures, can be measured and documented.

Hypertelorism Treatment 

Surgery for hypertelorism is mostly for aesthetic reasons. It necessitates extensive surgery that must be approached both intracranially and extracranially. Paul Tessier was a pioneer in hypertelorism surgery. He was the one who established that orbits could be adjusted without impairing vision. The surgery's goal is to bring the two orbits together medially and repair any dystopia, as well as to fix the nasal dorsal part and remove extra skin.

Surgery is commonly performed between the ages of 5 and 7 years. Before the age of five years, inferior excision may disrupt maxillary arch bone development, which may compromise tooth formation. Furthermore, the bones may be too frail to hold the osteotomies together. Treatment, on the other hand, is more predictable in adults; the psychological effects of an aesthetic flaw demand early surgery. If craniosynostosis is present, it must be repaired independently before the age of one year.

Box osteotomy, face bipartition, and U-shaped osteotomy are surgical alternatives. The approaches are determined by the preoperative examination. The presence of related anomalies, the architecture of the maxillary arch, the axis of the orbit, and the degree of hypertelorism all influence the treatment chosen.

Hypotelorism

Hypotelorism is defined as an abnormal decrease in distance between any two organs, while some writers use the term interchangeably with orbital hypotelorism, which is defined as an abnormal decrease in distance between the two eyes (the eyes appear too close together).

Hypotelorism Causes 

It is frequently the outcome of fetal alcohol syndrome (FAS), which is caused by excessive alcohol use during the first month of pregnancy. It has been linked to trisomy 13, often known as Patau syndrome, and hereditary neuralgic amyotrophy.

It is also linked to fragile X syndrome and Prader–Willi syndrome. Metopic synostosis, or the premature closure of the metopic suture during childhood skull growth, can also result in hypotelorism.

Coloboma

A coloboma of the eyelid is a full-thickness deformity of the eyelid. Although eyelid colobomas can form in a variety of sites, the most prevalent is at the intersection of the medial and center thirds of the top lid. Within the coloboma, no lid appendages or ancillary structures are normally visible.

Pathophysiology

An eyelid coloboma can develop at birth or as a result of trauma (eg, accidental, surgical). Treacher Collins syndrome, which is autosomal dominant with varying penetrance and expressivity, is nearly always characterized by an eyelid coloboma.

Medical Care

The primary objective of medical treatment for eyelid colobomas is corneal protection. Modalities that can be employed for either modest or big problems while waiting for definitive surgical therapy include the following:

• Artificial tears and ointment
• Moist chamber optical bandages
• Bedtime patching

Surgical Care

Corneal protection and cosmesis are surgical indications. The surgical method used is determined on the size and location of the problem.

If the eyelid coloboma is mild and manageable with topical lubrication, surgery may be postponed until later in childhood. It is usually rectified by straight closure. Sharp incisions are used to clean up the margins of the defect, and accurate anastomosis is performed. The lid margin is joined using a two-layer approximation of the tarsus and skin. To reduce horizontal stress, lateral cantholysis and the implantation of near-far and far-near sutures may be required.

If the coloboma on the eyelid is substantial, rapid surgical closure is typically required to prevent corneal impairment. For abnormalities that take up more than 40-50 percent of the lid, a two-stage repair may be necessary. 

Coloboma Complications

The most prevalent complication of any juvenile eye condition is amblyopia. It must be excluded and, if found, treated. In the pediatric population, eyelid-sharing operations such as the Hughes procedure and the Cutler-Beard (unmodified) technique should be utilized with caution.

Excision of related limbal dermoids should be done with caution. Complications such as pseudodopterygium and symblepharon, as well as perforation, are prevalent. Lamellar grafts have been recommended.

Microphthalmia and Anophthalmia

Anophthalmia and microphthalmia are terms that describe the lack of an eye and the presence of a tiny eye within the orbit, respectively. The total birth prevalence of these diseases is up to 30 per 100,000 people, with microphthalmia occurring in up to 11% of blind children. High-resolution cerebral imaging, post-mortem investigation, and genetic research all point to these diseases being part of a phenotypic continuum.

Anophthalmia and microphthalmia can occur alone or as part of a syndrome, as in one-third of cases. Anophthalmia and microphthalmia have a complicated etiology, with chromosomal, monogenic, and environmental factors identified. There are chromosomal duplications, deletions, and translocations involved. Only SOX2 has been identified as a key causal gene in monogenic causes.

Anophthalmia and microphthalmia meaning

The lack of ocular tissue in the orbit is referred to as anophthalmia. In the absence of clinically visible ocular tissue, histological sectioning has revealed residual neuroectoderm in some cases, suggesting that terms like 'true anophthalmia,' 'clinical anophthalmia,' and 'extreme microphthalmia' may actually refer to a phenotypic range between anophthalmia and microphthalmia.'

Clinically, it is fair to use the term microphthalmia for an eye with an axial length two standard deviations below the population age-adjusted mean; in adult eyes, this generally translates to an axial length less than 21 mm. The term "simple microphthalmia" refers to a structurally normal, tiny eye and has been used interchangeably with the term "nanophthalmia."

The increased sclera thickness in these eyes, as well as the resulting alterations in blood flow, are thought to be responsible for the greater incidence of uveal effusions and choroidal detachments noted. When microphthalmia is associated with other ocular disorders, it is referred to as complex microphthalmia.

These ocular disorders may affect the anterior segment

• Sclerocornea 
• Peters anomaly

and/or the posterior segment 

• Persistent hyperplastic primary vitreous 
• Retinal dysplasias

Anophthalmia Diagnosis

The diagnosis is mainly based on clinical and imaging criteria, and histology may be used to confirm the diagnosis if a post-mortem is conducted. A detailed medical history, physical examination, family history, karyotyping and molecular genetic testing, imaging, renal ultrasonography, and hearing are all used to determine a particular etiology.

Anophthalmia is a potentially challenging clinical diagnosis. Inspection and palpation of the eye via the lids is commonly used to diagnose microphthalmia. Diagnosis is helped by corneal diameter measures, which vary from 9–10.5 mm in newborns to 10.5–12 mm in adults. Lower lid bulging is the most common symptom of microphthalmia with cyst. Electrodiagnostic testing may be useful, especially in situations of microphthalmia in which retinal development has not been compromised. Both parents' eyes should be examined, and a comprehensive family history of eye abnormalities should be obtained.

Imaging

In microphthalmic eyes, ultrasound is most typically used to estimate the length of the globe.

Anophthalmia can be diagnosed more easily with CT and MR scans. Both scans demonstrate that there is no globe within the orbit, yet soft amorphous tissue may be seen (intermediate T1 signal intensity and low T2 signal intensity on MR scan, intermediate density on CT scan). The presence of neural tissue composing the visual pathway and extraocular muscles varies. Both the orbital size and volume are lowered. Simple microphthalmia manifests as a normal, albeit tiny, globe with normal signal/density properties of the lens and vitreous in a smaller orbit than usual.

Anophthalmia Management

• Conservative

Patients with microphthalmia who have detectable retinal function, particularly those with SOX2 mutations, may have detectable retinal function. Refracting these eyes and treating any underlying amblyopia is crucial. In unilateral settings, the 'good' eye must be protected, and any visual impairment must be carefully managed.

• Surgical

The majority of anophthalmia/microphthalmia treatment might be surgical surgery. Between birth and puberty, the volume of the earth triples. The expansion of the bony orbit corresponds to the expansion of the planet. When compared to age-matched controls, both congenital anophthalmia and microphthalmia result in a small volume orbit, potentially contributing to the appearance of hemifacial asymmetry.

There is also evidence that enucleation (globe removal) reduces orbital capacity in both children and adults. Reconstructive techniques focus on managing both soft tissue hypoplasia and asymmetric bone development at the same time.

Treatment is often initiated early in order to maximize these children's overall development. Mild/moderate microphthalmia is often treated conservatively with the implantation of a conformer (similar to a prosthetic eye but not painted), which is gradually increased in size to allow for orbital expansion. Treatment for severe microphthalmia and anophthalmia is generally initiated after a few weeks of birth, with conformers used to widen the palpebral fissure, conjunctival cul-de-sac, and orbit.

After six months of age, endo-orbital volume replacement with implants of progressively increasing size can be utilized to induce enlargement of the developing bony orbit. Dermis-fat grafts can be used to enhance volume restoration utilizing implants and expanders. Static orbital implants may need to be replaced three to five times before puberty, and they are linked with wound dehiscence, extrusion, or insufficient stimulation of bone development.

Expandable orbital implants were established as a highly effective method of encouraging bone development and socket expansion. Inflatable expanders are constrained by the difficulties of maintaining orbital attachment for continuous expansion and regulating expansion direction, whereas self-expanding hydrogel spheres lose expansion force once completely hydrated. In more severe situations, orbital osteotomies are recommended.

When the orbit has matured sufficiently, ocular prosthesis is employed, and they are replaced on a regular basis as the orbit expands. Conjunctival sac and lid restoration may improve the overall aesthetic result.

Microphthalmia with cyst is frequently treated around the age of five, allowing the ophthalmic surgeon to take advantage of the cyst's orbital expansion properties until the orbit is approximately 90% of the adult volume, while also allowing removal for cosmetic reasons around the time the child begins school. Surgical excision with prior decompression is the most usual procedure; the cyst can also be aspirated, although the recurrence rate is greater.

Aniridia

Aniridia is described as the absence of the iris, which can be partial or full. Aniridia can be inherited or acquired. Congenital aniridia is an uncommon condition that affects both eyes at birth. The majority of cases are autosomal dominant. The majority of other occurrences of congenital aniridia are sporadic. WAGR syndrome may be associated with sporadic aniridia (Wilm tumor, aniridia, genitourinary anomalies, and mental retardation)

Since early childhood, patients typically complain of photophobia related to the severity of aniridia and impaired eyesight (due to a variety of causes, including foveal hypoplasia and optic nerve head hypoplasia). Parents may bring their children for aberrant eye look.

In foveal hypoplasia, optical coherence tomography reveals the absence of foveal depression and the existence of the inner retinal layers. The necessity of ophthalmic examination of family members cannot be overstated.

Early childhood care involves optimum refractive correction, amblyopia therapy, and squint correction. Painted contact lenses may help with photophobia, cosmesis, and eyesight. Tinted contact lenses are another option. These contact lenses also help to minimize nystagmus. Photochromatic or colored spectacles may come in handy.

Conclusion 

There are many different types of eye illnesses and visual difficulties. Some are incurable, but many are treatable. The degree of the anomalies and the ocular structures affected determine the severity of the symptoms. Children with severe instances may have impaired eyesight, light sensitivity, and odd eye movements.

Congenital eye illnesses come in a variety of forms. To improve and/or preserve eyesight, eye surgery may be required. Depending on the ocular structures implicated and the degree of the anomalies, several forms of surgery may be done.