Scleral melt is a serious eye condition affecting the sclera, the white outer layer of the eye. This condition involves the progressive thinning and degradation of scleral tissue.
Understanding Scleral Melt
The sclera is the tough, fibrous, opaque white outer layer of the eye, forming about five-sixths of its connective tissue coat. It extends from the clear cornea at the front of the eye to the optic nerve at the back, providing structural integrity and maintaining the eyeball’s shape. This protective layer is primarily composed of collagen fibers arranged in a crisscrossing pattern, which contributes to its strength and flexibility.
Scleral melt, also known as scleromalacia perforans, describes a progressive weakening and thinning of this scleral tissue. This process involves the proteolytic degradation of collagen and other extracellular matrix components within the sclera, leading to stromal degradation. If left unaddressed, this thinning can advance to the point of perforation, where a hole forms in the sclera, potentially exposing underlying eye structures.
The thickness of the sclera varies. This degradation can compromise the eye’s structural integrity, making it more vulnerable to external forces and internal pressure changes.
Causes of Scleral Melt
Scleral melt can arise from systemic conditions and local influences. Systemic autoimmune diseases are frequently implicated, causing inflammation and tissue destruction throughout the body, including the eyes. Examples include rheumatoid arthritis, granulomatosis with polyangiitis, lupus, sero-negative spondylarthropathies, and polyarteritis nodosa.
Local factors can also trigger scleral melt, often in combination with systemic predispositions. Infections can damage scleral tissue, leading to thinning. Severe trauma to the eye can also initiate a melting process. Complications from previous eye surgeries are a recognized cause.
Specific surgical procedures linked to scleral thinning and melt include pterygium excision, cataract surgery, and vitrectomy. The use of adjuncts like mitomycin C (MMC) or adjunctive irradiation can increase this risk. High myopia, a condition where the eye is elongated, can also predispose individuals to scleral thinning.
Recognizing Scleral Melt
Identifying scleral melt involves observing specific signs and symptoms that indicate a compromise of the eye’s outer layer. Patients may experience severe eye pain, often accompanied by noticeable redness in the affected eye. Light sensitivity, known as photophobia, is another common symptom that can occur as the condition progresses. Changes in vision may also be reported, ranging from blurriness to more significant visual impairment.
A visible thinning or discoloration of the white part of the eye is a direct sign of scleral melt. As the sclera thins, the underlying dark choroid, which is the vascular layer beneath the sclera, may become visible through the weakened tissue, appearing as a dark area on the eye’s surface. These symptoms warrant immediate evaluation by an eye care professional to confirm the diagnosis and initiate appropriate management.
Treatment for Scleral Melt
Treatment for scleral melt involves a dual approach, addressing both the underlying cause and the local eye condition. When systemic autoimmune diseases are the root cause, managing these conditions with systemic immunosuppressive therapy is a primary focus. This can involve medications like oral corticosteroids, often starting with a dose such as 1 mg/kg/day of prednisone, which is then gradually reduced. Immunosuppressants may also be used, particularly in cases unresponsive to corticosteroids or for necrotizing disease.
Local eye treatment directly targets the scleral damage. Topical medications, such as steroid drops, can be prescribed to reduce inflammation. If an infection is present, antibiotics are administered to eliminate the causative microorganisms. Surgical interventions are frequently necessary, especially when ocular integrity is compromised or perforation is a risk.
Scleral grafting is a common surgical procedure where donor tissue, such as preserved sclera, pericardium, cadaveric dura mater, or amniotic membrane, is used to repair the weakened area. This patch graft material helps to reinforce the thinned sclera and prevent further degradation. Conjunctival flaps, where a piece of the conjunctiva is moved to cover the affected area, can also be employed to promote healing and provide a protective layer. These multi-faceted approaches aim to stabilize the eye and preserve vision.
Prognosis and Ongoing Care
The outcome of scleral melt largely depends on early diagnosis and aggressive treatment, which are important for preserving vision and maintaining the eye’s structural integrity. If the condition is left untreated or progresses rapidly, there is a substantial risk of significant vision loss or even the complete loss of the eye. The progressive thinning can lead to globe perforation and uveal prolapse, which are considered ocular emergencies requiring prompt management to prevent severe complications like endophthalmitis.
Long-term follow-up and continuous monitoring are necessary, particularly for individuals with underlying systemic diseases that predispose them to scleral melt. Regular examinations help manage the condition, detect any recurrence, and adjust treatment protocols as needed. This ongoing medical oversight is important to maintain ocular health and prevent future complications.