A lamellar macular hole is an eye condition affecting the macula, a specialized part of the retina. It involves a partial defect in the retina’s central light-sensitive tissue. Unlike a full-thickness macular hole, it does not create a complete hole through all retinal layers. This can influence central vision clarity.
Understanding Lamellar Macular Holes
The macula, located at the center of the retina, is responsible for sharp, detailed central vision, enabling tasks like reading and recognizing faces. This oval-shaped area contains a high concentration of photoreceptor cells, particularly cones, which convert light into signals for the brain. The macula is yellow due to the presence of lutein and zeaxanthin, carotenoids that also provide a natural protective filter against blue and ultraviolet light.
A lamellar macular hole is a partial-thickness defect in the fovea, the center of the macula. It involves a splitting of the inner retinal layers, while outer photoreceptor layers generally remain intact. The foveal contour, which is normally a smooth depression, appears irregular. This differs from a full-thickness macular hole, where a complete break extends through all retinal layers.
The causes of lamellar macular holes are not fully understood; many cases are idiopathic. However, certain factors are associated with their development. These include tractional forces from the vitreous gel or from an epiretinal membrane (ERM) on the retinal surface. They can also be linked to conditions like cystoid macular edema, where fluid accumulation may lead to a rupture in the foveal tissue.
How OCT Diagnoses Lamellar Macular Holes
Optical Coherence Tomography (OCT) is a non-invasive imaging test providing detailed cross-sectional images of the retina, allowing eye care professionals to view its intricate layered structure. OCT is widely used to diagnose and characterize lamellar macular holes, revealing subtle anatomical changes not visible during a standard eye examination. OCT helps differentiate this condition from other macular disorders, such as macular pseudohole or vitreomacular traction.
On an OCT scan, specific features indicate a lamellar macular hole. A primary sign is an irregular foveal contour, where the macula’s normally smooth depression appears uneven. There is also a distinct break in the inner foveal layers of the retina. A characteristic finding is intraretinal splitting or cavitation, appearing as a separation within the retinal layers, often between the outer plexiform and outer nuclear layers.
A distinguishing characteristic on OCT is the preservation of outer photoreceptor layers, including the ellipsoid layer, which remain intact despite the inner retinal defect. The edges of the foveal defect may appear undermined or excavated. OCT also helps classify lamellar macular holes into subtypes, such as tractional and degenerative, based on associated epiretinal membranes and the nature of the intraretinal separation. Tractional types often show a “schisis-like” appearance with an intact ellipsoid layer, while degenerative types may present with round-edged intraretinal cavitation and ellipsoid zone disruption.
Recognizing Symptoms and Progression
Individuals with a lamellar macular hole may experience various visual symptoms, though these are milder compared to those associated with a full-thickness macular hole. Common complaints include blurred central vision, making fine details difficult to discern. Distorted vision, known as metamorphopsia, is also reported, where straight lines may appear wavy or bent. Some people may also notice a central blind spot, or scotoma, in their field of vision.
Symptoms often develop gradually, and the condition may be discovered during a routine eye examination even without noticeable symptoms. While vision loss can occur, it is less severe than with other macular holes, and many individuals experience little to no change in their overall vision. The condition often remains stable over time, with vision not progressively worsening in most cases.
Despite general stability, a lamellar macular hole can, in rare instances, worsen or progress. Studies indicate that a small percentage of cases (approximately 13% to 21%) may show anatomical decline over an 18 to 24-month period. A visual acuity loss of more than five letters on an eye chart can occur in about 19.5% of eyes over three years. Progression to a full-thickness macular hole is also possible, particularly in cases with associated epiretinal proliferation, though this remains less common.
Treatment and Prognosis
Management for lamellar macular holes depends on the individual’s visual symptoms and the condition’s stability. Many cases are monitored without active treatment, especially if vision remains stable and symptoms are mild. Regular follow-up examinations, often involving OCT imaging, are conducted to observe for changes in the hole’s structure or visual function. This conservative approach is based on the tendency of many lamellar macular holes to remain stable over long periods.
Intervention may be considered if there is a significant decline in vision, if symptoms become severe and impact daily activities, or if the hole shows signs of progression towards a full-thickness macular hole. Surgical treatment, while sometimes controversial, can be an option for lesions that are progressing or causing considerable visual impairment. The primary surgical procedure is pars plana vitrectomy (PPV), which involves removing the vitreous gel.
During PPV, associated preretinal tissues, such as epiretinal membranes or epiretinal proliferation, are often peeled from the retinal surface. Peeling of the internal limiting membrane (ILM), the innermost layer of the retina, may also be performed to relieve traction. A temporary gas or air bubble may then be injected to help flatten the retina and facilitate healing. While surgical outcomes vary, some studies report improvements in visual acuity, particularly in tractional types, with some patients gaining several lines of vision. However, postoperative visual loss can occur in a small percentage of cases, ranging from 0% to 20%.