Scleroplasty: Options, Techniques, and Benefits for Myopia

Progressive myopia, or worsening nearsightedness, can lead to structural changes in the eye that increase the risk of complications such as retinal detachment and macular degeneration. While glasses and contact lenses correct vision, they do not address the underlying issue of excessive eyeball elongation.

Scleroplasty is a surgical procedure designed to reinforce the sclera—the white outer layer of the eye—to slow or stabilize myopia progression. Various techniques and materials have been explored, each with distinct benefits and limitations.

Scleral Architecture In Nearsightedness

The sclera, a dense connective tissue forming the eye’s outermost layer, maintains ocular shape and resists intraocular pressure. In progressive myopia, this supportive framework weakens, leading to excessive axial elongation. Unlike the stable scleral composition in non-myopic eyes, myopic sclera exhibits thinning, reduced collagen density, and biomechanical weakening, particularly in the posterior pole, where mechanical stress is highest. In severe cases, this can result in posterior staphyloma.

Histological studies show that myopic sclera has smaller collagen fibrils and an altered extracellular matrix composition. Reduced glycosaminoglycans and proteoglycans, essential for hydration and tensile strength, contribute to a more compliant, less resistant scleral structure. Both genetic predisposition and environmental factors, such as prolonged near work and insufficient outdoor exposure, influence this remodeling process. Experimental models indicate that scleral fibroblasts in myopic eyes exhibit downregulated collagen synthesis genes, further exacerbating structural weakening.

Biomechanical assessments using atomic force microscopy and ultrasound elastography confirm that myopic sclera has lower stiffness and increased viscoelasticity, making it less capable of withstanding intraocular forces. This mechanical vulnerability is particularly concerning in high myopia, where excessive stretching increases the risk of complications such as chorioretinal atrophy and myopic maculopathy.

Primary Goal Of Reinforcement

Scleroplasty aims to mechanically strengthen the sclera and counteract axial elongation. This elongation results from a biomechanical imbalance where weakened scleral tissue cannot resist forces driving excessive eye growth. Reinforcing the posterior sclera restores structural integrity, slowing elongation and reducing the risk of complications like retinal detachment and myopic maculopathy.

Scleral reinforcement focuses on the posterior pole, where mechanical strain is highest. Optical coherence tomography (OCT) and high-resolution ultrasound imaging show that thinning and biomechanical weakening are most pronounced in this area. By introducing grafts or synthetic materials, scleroplasty redistributes stress across the scleral shell, slowing elongation and preventing localized deformation, which can lead to posterior staphyloma and chorioretinal atrophy.

The success of scleral reinforcement depends on its ability to integrate with ocular tissues without inducing excessive inflammation or compromising function. Research shows that reinforcement increases tensile strength and reduces susceptibility to further stretching. Finite element modeling studies indicate that reinforcing the posterior sclera can reduce axial elongation rates, particularly in high myopia. Longitudinal studies tracking post-scleroplasty patients report stabilization of refractive error progression, with some cases showing a complete halt in axial growth over several years.

Tissue Options For Surgical Reinforcement

The choice of reinforcement material significantly impacts the success and longevity of scleroplasty. Various biological and synthetic options have been explored, each with distinct advantages and limitations in terms of biocompatibility, structural integrity, and long-term stability.

Autologous Tissues

Autologous tissues, harvested from the patient’s own body, offer excellent biocompatibility and minimal immune rejection risk. Common sources include fascia lata from the thigh and periosteum from the bone surface. These tissues provide mechanical reinforcement while integrating well with the scleral matrix. Studies show that fascia lata grafts maintain structural integrity over time, reducing the likelihood of resorption.

A drawback of autologous grafts is the need for an additional surgical site, increasing operative time and potential morbidity. Harvesting fascia lata requires a thigh incision, which can cause postoperative discomfort and scarring. Tissue availability may also be a concern in pediatric patients or individuals with thin connective tissue. Despite these challenges, autologous grafts are preferred when long-term stability and minimal immune response are priorities.

Donor Tissues

Allogeneic donor tissues, such as preserved sclera or dura mater, provide an alternative to autologous grafts without requiring additional surgical harvesting. Sourced from human cadaveric donors, these tissues undergo processing to remove cellular components, reducing immune rejection risk. Cryopreserved or chemically treated scleral grafts integrate well with host tissue and effectively reinforce the posterior pole.

A concern with donor tissues is the potential for disease transmission, though modern sterilization techniques and rigorous donor screening have minimized this risk. Additionally, some allogeneic grafts may gradually resorb, diminishing mechanical support over time. Despite these limitations, donor sclera remains a viable option, particularly when autologous tissue is unavailable or a less invasive approach is preferred.

Synthetic Substances

Synthetic materials, such as polytetrafluoroethylene (PTFE), silicone bands, and collagen-based scaffolds, offer a non-biological alternative for scleral reinforcement. Designed to provide durable mechanical support, they minimize risks associated with tissue grafts, such as resorption or immune rejection. PTFE, commonly used in vascular grafts, has been explored for scleroplasty due to its high tensile strength and resistance to degradation.

A major advantage of synthetic materials is their consistent quality and availability, eliminating variability associated with biological grafts. However, concerns remain regarding long-term biocompatibility, as some synthetic implants may induce chronic inflammation or fibrosis. Additionally, rigid materials may not fully mimic the viscoelastic properties of natural sclera, potentially leading to localized stress concentrations. Research continues on bioengineered scaffolds that combine synthetic durability with enhanced biocompatibility, offering a promising direction for future scleral reinforcement.

Reinforcement Techniques

Scleroplasty employs various techniques to strengthen the sclera and slow axial elongation. The method selected depends on disease severity, patient age, and surgeon preference, aiming to provide structural support while minimizing surgical trauma.

One widely used technique involves placing reinforcement material over the posterior sclera through a small incision, allowing grafts or synthetic scaffolds to integrate with existing tissue. This procedure, performed under local or general anesthesia, ensures the reinforcement targets the most biomechanically weakened area.

Another approach secures the reinforcing material with sutures or adhesive fixation, preventing displacement and ensuring even distribution of mechanical support. Some variations use overlapping layers of graft material to create a scaffold-like structure that enhances tensile strength without impeding normal ocular function.

Minimally invasive adaptations, such as trans-scleral injection of bioengineered hydrogels, are being explored as alternatives to traditional grafting techniques. These hydrogels polymerize in situ, providing customizable reinforcement while reducing the need for extensive surgical dissection.