Contributor: Antonio P. Ciardella
Foveal detachment (stage 1 macular hole) is the precursor of a macular hole [hole - macula]. The visual acuity in these individuals is typically in the 20/25 to 20/70 range. The vitreous is clear and attached. Biomicroscopic examination with a thin beam of light demonstrates a decreased or absent foveal depression, but no definite evidence of dehiscence in the retina. Depending on how soon the patient is examined after the onset of symptoms and the degree of elevation of the retina, either a yellow spot 100-200 mm.in diameter (stage 1A) or a yellow ring (stage 1B) is present in the foveolar area. A few fine radiating retinal striae, seen best by retroillumination, often surround the yellow ring. The yellow lesion represents a focal schisis or detachment of the retina, first in the foveolar and then in the foveal area as a result of focal shrinkage of prefoveolar vitreous cortex and tangential retinal traction. The yellow color is probably caused by a greater visibility of the highly concentrated xanthophyll in the area of focal separation from the retinal pigment epithelium. As the foveolar retinal detachment progresses to foveal retinal detachment, the progressive stretching and thinning of the foveolar center may cause the redistribution of the xanthophyll into a ring configuration. OCT examination demonstrates that initially the formation of a macular hole comprises a partial perifoveal posterior hyaloid detachment, which results in vitreo-foveal traction and in a split at the foveal center, in the inner part of the foveal tissue resulting in the formation of a foveal pseudocyst. OCT shows also that the pseudocyst usually occupies the inner part of the foveola, which results in foveolar thickening and corresponds to a stage 1A impending macular hole. In the stage 1B impending hole, characterized by a yellow ring on biomicroscopy, the pseudocyst extends posteriorly, disrupting the outer retinal layer at the foveal center. The unroofing of the foveal pseudocyst results in a lamellar hole if the base of the pseudocyst is preserved and in a full-thickness hole if the outer retinal layer is disrupted. In about 40% of cases of stage 1 macular hole there may be spontaneous separation of the vitreous from the fovea without formation of a full-thickness macular hole. These patient usually experience improvement in visual symptoms and acuity. Biomicroscopy examination demonstrates foveal reattachment in all cases. Other frequent findings are a vitreofoveal opacity suspended in the posterior hyaloid face immediately in front of the normal foveolar retina. In some eyes foveal reattachment is associated with a lamellar dehiscence of the inner retina and operculum formation. In some cases a larger, reddish lamellar hole may occur.