Sclerocornea - Causes, Symptoms, Diagnosis, and Management

Introduction:

The eye is a sensory organ protected by the bony orbit. It can move with the action of the extraocular muscles attached to the sclera, the white part of the eye. The sclera is a string layer covering the entire eyeball. In addition, a transparent dome-shaped portion in front of the eye is called the cornea, through which light is transmitted to the eye. When these two structures, the sclera and the cornea, blend, it results in sclerocornea, where there is a dominance of the sclera and not the cornea.

What Does the Sclera Do?

The sclera acts as a supporting wall to the eye. It maintains the shape and protects the eye from injury. As the seven extraocular muscles are attached to the sclera, they aid in the eye's up, down, and side movements.

What Does the Cornea Do?

The cornea shares the task of protecting the eyes from germs, dust, and other harmful substances with tears, eyelids, eye sockets, and sclera. In addition, the cornea, the structure in the anterior portion of the eye, acts as a window through which light entry is controlled.

What Are Corneal Opacities?

Corneal opacity is a condition where the cornea's transparency is lost and scarred. This leads to the restriction of light from passing through the cornea to the retina. A cloudy white appearance of the cornea characterizes this condition.

How Are Corneal Opacities Classified?

Corneal opacities are generally classified as congenital and acquired. They are then further classified as follows.

Congenital Corneal Opacities:-

• Sclerocornea.

• Cornea plana.

• Cornea tumors.

• Peters anomaly.

• Hereditary endothelial dystrophy.

• Hereditary stromal dystrophy.

• Posterior polymorphous corneal dystrophy.

• Congenital anterior staphyloma.

Acquired Corneal Opacities:-

• Corneal blood staining.

• Corneal keloids.

• Keratoconus.

• Corneal ulcers.

• Infantile glaucoma.

• Posterior corneal depression.

• Steven-Johnson syndrome.

What Is Sclerocornea?

Sclerocornea, also called sclerocornea totalis, is a congenital disorder with a problem developing cornea and sclera. As a result, there is complete scleralization of the cornea giving a white-eye appearance. There is no clear-cut boundary between the sclera and cornea. It can occur as an isolated condition or as part of a syndrome.

What Are the Causes of Sclerocornea?

Sclerocornea is found to go through families and occur sporadically. The inheritance is autosomal dominant or recessive. In autosomal recessive cases, the parents are not affected by the condition, but the child inherits one copy of the mutated gene from each parent. In autosomal dominant inheritance, the child inherits the mutated gene from any one of the parents. The disease is more severe in autosomal recessive inheritance than in dominant conditions. In addition, sclerocornea is found in association with other hereditary eye disorders.

What Are the Clinical Manifestations of Sclerocornea?

Sclerocornea can be unilateral or bilateral opacities affecting the peripheral, central, or entire cornea. The ocular abnormalities noticed in sclerocornea cases can be different for each individual.

However, the common ocular abnormalities are:

• Enophthalmos: It is the sinking of the eyeball.

• Blepharoptosis: Drooping of the upper eyelid blocking vision.

• Microphthalmus: Eyes are abnormally small.

• Macrophthalmus: Eyes are unusually large.

• Nystagmus: Involuntary circular movements of the eyes.

• Strabismus: One eye is turned in a direction opposite to the other eye.

• Myopia: Vision condition where the nearby objects are clear and far away objects are blurry.

• Coloboma: A defect of the iris of the eye.

• Glaucoma: A vision condition in which the optic nerve is affected.

• Flattened cornea.

• Decreased corneal sensation.

• Shallow anterior chamber of the eye.

• Increased intraocular pressure.

What Are the Symptoms of Corneal Opacities?

• Based on the shape of the cornea, there may be refractive errors such as nearsightedness and farsightedness.

• Tearing of the eyes.

• Redness and swelling of the eye tissues.

• Blurred vision.

• Irritation of the eyes.

• Sensitivity to light.

• Eye discharge.

• Vision loss.

What Are the Systemic Abnormalities Associated With Sclerocornea?

Not all individuals with sclerocornea have systemic abnormalities, but they are found in rare cases.The systemic abnormalities are:

• Biemond’s Syndrome: Hexadactyly of hands and feet and cavities of the parietal bones.

• Lobstein’s Syndrome: Fragile bones, blue sclera, and decreased hearing.

• Hurler’s Disease: Claw-like hands, abnormal bones in the spine, deafness, and heart valve problems.

How Is Sclerocornea Diagnosed?

The ophthalmologist can diagnose sclerocornea on inspection of the eye, revealing the loss of corneal clarity. However, a complete eye examination is required to identify whether the condition is sclerocornea or any other eye disorder. An ultrasound biomicroscopy can be used to diagnose the condition. It is a technique used to image the anterior segment of the eye. In addition, the technique can be used to visualize the cornea, iris, scleral spur, ciliary body, anterior chamber, posterior chamber, lens, and conjunctiva.

The other tests used for diagnosing corneal disorders include:

• Basic Corneal Examination - Slit-lamp biomicroscopy.

• Tests to Detect Alteration in Corneal Structure and Function - Keratometry, keratoscopy, computer-assisted videokeratography, ultrasonic pachymetry, and specular microscope.

• Tests to Detect Secondary Corneal Involvement - Cytological and microbiological examination.

How to Treat Sclerocornea?

If sclerocornea is unilateral, surgery can be performed if other ocular structures are normal. In the case of bilateral sclerocornea, penetrating keratoplasty is performed. In penetrating keratoplasty, the opaque cornea is cut using a circular cutting device (trephine). Next, a similar-sized portion of the donor cornea is cut using the trephine and sutured to the recipient’s eye. In addition, The abnormalities of other ocular structures should also be treated. For example, glaucoma should be treated to improve vision.

Conclusion:

Sclerocornea, a rare congenital condition of the eyes, has to be clearly identified earlier. Therefore, various investigations are done before concluding the condition as sclerocornea, as there are several corneal opacities. Then, the treatment modalities are decided based on the partial or total involvement of the cornea or if the condition is unilateral or bilateral. So both eyes should be carefully examined and treated. However, some other systemic anomalies occur in rare cases.