The macula is the small, central area of the retina responsible for sharp, detailed central vision, necessary for tasks like reading and recognizing faces. Macular schisis is a condition where the retina’s delicate layers begin to split or separate, creating fluid-filled spaces or clefts within the tissue. The term “schisis” derives from the Greek word for “splitting.” This structural compromise threatens the integrity of the photoreceptor cells that capture light, often leading to a loss of central visual function.
Understanding Macular Schisis
The retina is a complex, multi-layered tissue lining the back of the eye. Macular schisis occurs when this tissue separates internally, differentiating it from a retinal detachment where the entire neurosensory retina lifts away from the underlying tissue. This splitting typically occurs in the inner retinal layers, frequently involving the inner nuclear layer and the outer plexiform layer. The formation of these intraretinal cystic spaces is distinct from macular edema, which involves the general accumulation of fluid within the retinal layers.
The schisis cavity is formed by thin columns of tissue that stretch between the separated layers, giving the appearance of a sponge-like structure. The split is concentrated at the fovea, the center of the macula where vision is sharpest. This anatomical disruption affects the normal communication and function of the nerve cells, which are crucial for transmitting visual signals to the brain.
Underlying Causes and Associated Conditions
The most common form affecting the adult population is myopic macular schisis (MMS), also known as myopic traction maculopathy. This condition is strongly linked to high myopia, or severe nearsightedness, which causes the eyeball to elongate along its axis. As the eye stretches, the retina becomes thinned and taut. Mechanical forces from the vitreous gel or epiretinal membranes then pull on the macular tissue, physically tearing the retinal layers apart and initiating the schisis.
Another important cause, typically seen in children and young adults, is X-linked retinoschisis (XLRS), a hereditary condition. XLRS is caused by a mutation in the RS1 gene, which produces the retinoschisin protein. This protein acts as a cellular glue, helping retinal cells adhere to one another. When this protein is non-functional, the retina’s structural integrity is compromised, leading to spontaneous splitting. XLRS affects males almost exclusively and often presents with a characteristic “spoke-wheel” pattern of splitting in the macula.
Identifying Symptoms and Diagnostic Techniques
The visual symptoms of macular schisis often correlate with the degree and location of the retinal splitting. Patients frequently report blurred or diminished central vision, which can be progressive and painless. Another common symptom is metamorphopsia, where straight lines appear wavy or distorted, a direct consequence of the macula’s uneven surface. If the splitting is advanced, a scotoma, or blind spot in the field of vision, may be noticed.
The definitive diagnostic method is Optical Coherence Tomography (OCT). This non-invasive imaging technique uses light waves to create high-resolution, cross-sectional images of the retina. OCT allows eye care professionals to visualize the internal split and the specific retinal layers involved, clearly showing the cystic spaces and tractional forces. This technology is essential for confirming the diagnosis and differentiating schisis from other macular conditions.
Additional Diagnostic Tools
Fundus photography captures a wide-field color image of the retina’s surface, which can reveal associated findings like an epiretinal membrane or a posterior staphyloma in highly myopic eyes. B-scan ultrasonography may be employed when clarity is compromised, such as in the presence of a cataract or vitreous hemorrhage. Ultrasonography provides a two-dimensional view of the eye’s internal structures to assess the extent of the schisis or rule out a complex detachment.
Treatment and Long-Term Monitoring
The initial management strategy often involves careful observation, especially if the patient’s vision is stable and the schisis is not rapidly progressing. Since intervention carries inherent surgical risks, some cases of myopic macular schisis can remain non-progressive for years. Regular monitoring with OCT is performed to detect changes in the splitting pattern or the onset of complications, such as a full-thickness macular hole or retinal detachment.
Surgical intervention is typically considered when there is evidence of progressive vision loss or the development of associated complications that threaten the macula’s viability. The procedure most often performed is a pars plana vitrectomy, where the vitreous gel is removed to relieve the forward traction it may be exerting on the retina. During this surgery, the surgeon may also perform an internal limiting membrane (ILM) peeling. Removing the ILM helps to completely release the tangential tractional forces pulling the retinal layers apart, promoting the re-apposition of the split tissue.
To encourage the macula to flatten and the schisis to resolve, a temporary intraocular tamponade agent is often injected into the eye. This agent is usually a gas bubble or silicone oil, which holds the retina in place while it heals. Patients receiving a gas bubble must maintain a specific head position, often face-down, for several days or weeks to ensure the bubble applies pressure to the macula. Long-term monitoring is necessary because macular schisis, particularly in highly myopic eyes, is a dynamic and chronic condition. Follow-up examinations and repeat OCT scans are performed to check for recurrence, the development of new traction, or other complications.