The term “macular hole” was first used to describe a partial- or full-thickness hole in the foveolar area. The area is susceptible to degeneration and hole formation because of its extreme thinness, avascularity, and lack of support by the neural and Müller cells.
The firm attachment of the vitreous to the basal lamina in the perifoval area may be important in the pathogenesis of hole formation.1
The definitions of macular pseudohole (MPH) and lamellar macular hole (LMH) have been the subject of much discussion. A loss of foveal tissue is mandatory for a diagnosis of LMH2 (Figure 1).
The exact cause of macular hole remains unknown. The first reported macular holes in the late 19th century were believed to result from trauma that caused cystoid changes in the macula.
Concurrent with the discovery around 1970 that the majority of macular holes were not associated with trauma, the predominant thought was that macular hole etiology was related solely to the presence of cystoid macular edema (CME) (Figure 1).3
Macular cysts are most often the result of chronic edema with coalescence of smaller cysts into a single or several larger cysts. Diabetic macular edema (DME) is a common condition associated with macular cysts.
In a study of 90 macular holes, trauma was involved in nine instances. The remaining cases were idiopathic, although ametropia and systemic hypertension were possible factors.4
Retinal pigment epithelial hypertrophy and hyperplasia may be seen in the area of both lamellar and complete macular holes. Outer LMHs may be seen with the breakdown of the blood ocular barrier at the retinal pigment epithelium (RPE) level. Retinal glial cells may grow onto the inner surface of the retina at the margin of a lamellar or complete macular hole.
Occasionally, a hole or attenuated area in an epiretinal membrane (ERM) in the macular area may simulate a macular hole (pseudohole).5
Diabetes mellitus was the most common condition associated with macular cysts. Residual CME was the most prevalent accompanying pathologic feature.
Wrinkling of the internal limiting membrane (ILM) and/or vitreous traction with or without an operculum was infrequently associated with macular hole.
Primary macular hole is commonly idiopathic.
Secondary macular hole occurs when the hole is caused by other pathologies not associated with VTM.