Idiopathic Macular Hole
Sandeep Saxena. MS, MAMS.
Professor
Department of ophthalmology
CSM Medical University (Erstwhile King George’s Medical University)
Lucknow, U.P.
sandeepsaxena2020@yahoo.com
Introduction
Recent advances in the pathogenesis, classification, and surgical intervention of idiopathic macular holes have generated a renewed interest in this entity. Better indicators of visual outcome as well as refinements in the surgical technique have led to improvements in the success of macular hole surgery.
Clinical characterization and theories on the pathogenesis of macular hole have continued to evolve. Although originally thought to be the result of trauma, it is now recognized that most macular holes occur in the absence of antecedent injury and are referred to as idiopathic. Theories for the pathogenesis of idiopathic macular holes have included progressive thinning of the foveal tissue and prehole cyst formation. The primary pathogenic role of the vitreous was suggested by studies that indicated a low relative risk for macular hole formation in eyes with complete posterior vitreous detachment.
Gass proposed a theory whereby shrinkage of adherent cortical vitreous and subsequent tangential vitreous traction first cause a circumscribed foveolar detachment (stage I) followed by early retinal dehiscence (stage II), then enlargement of the macular hole with vitreofoveal separation (stage III) and finally complete posterior vitreous detachment (stage IV).
Guyer and Green proposed three mechanisms of tangential traction on the macula, including fluid movements and counter currents, cellular remodeling of cortical vitreous, and contraction of a cellular membrane on the inner surface of the tapered cortical vitreous. Gass emphasized the difficulty in distinguishing posterior vitreous detachment from a zone of posterior vitreous liquefaction and attached posterior cortical vitreous over the macula. He also emphasized that unless the posterior cortical vitreous contains the vitreous condensation ring (Weiss’s ring) over the optic nerve, an operculum, or a pseudo-operculum, the diagnosis of posterior vitreous detachment is uncertain.
Clinical Features
Idiopathic macular holes occur most frequently in the sixth decade of life. According to Gass, stage IA and IB lesions represent focal foveal detachments secondary to vitreous traction. A 100- to 200- um diameter yellow spot is the earliest change observed. With progression, a 200- to 350-um yellowish ring develops. Fine radiating striae are often seen surrounding the yellow ring. The vision is in the range of 20/25 to 20/70. Within several weeks to months, a full-thickness dehiscence develops. This dehiscence often starts eccentrically, and then opens in a “can-opener” fashion to form a crescentic retinal defect, then a horseshoe-shaped hole, and finally a round hole with an operculum. In some cases, the dehiscence starts centrally, with gradual enlargement of the hole, and no operculum develops. A ring of retinal detachment usually surrounds the hole. As the hole enlarges, the vision generally decreases and within several months it progresses to a fully developed hole that measures approximately 500um in diameter. When present, the operculum is suspended over the hole by the detached vitreous cortex. With time, round yellow deposits on the central retinal pigment epithelium, epiretinal membranes that cause contracture of the internal limiting membrane, depigmentation of the pigment epithelium under the cuff of retinal elevation, and a pigmentary demarcation ring defining the outer margin of the retinal detachment may be observed. Vision is usually in the range of 20/70 to 20/400. Posterior vitreous separation from the macula and disk develops in a small percentage of cases.
Eyes with idiopathic macular hole loose vision secondary to tissue dehiscence, cystic changes, and retinal cuff elevation with photoreceptor degeneration. Clinical observations have led to the impression that the macular hole and cuff enlarge secondary to persistent tangential traction from the vitreous, tangential traction from epiretinal membranes, and the development of large cystic spaces within the surrounding cuff.
Optical Coherence Tomography
Optical coherence tomography staging is as follows (Figs. 1-4):
Stage 1A: Partial thickness pseudocyst with perifoveal posterior vitreous detachment
Stage 1B: Full thickness pseudocyst with roof
Stage 2A: Full thickness macular hole with partial opening of the roof, focal vitreous attachment to flap
Stage 2B: Full thickness operculated macular hole, traction to retina released
Stage 3: Full thickness operculated macular hole, traction released, ≥400µm diameter
Stage 4: Full thickness macular hole with complete posterior vitreous detachment, vitreous face may or may not be evident on optical coherence tomography (OCT).
Fig. 1. Stage 1A idiopathic macular hole. OCT highlights perifoveolar posterior vitreous detachment with continued foveolar adherence and obliquely oriented tractional forces. Retinal tissue remains at the base of the pseudocyst.
Fig. 2. Stage 2A idiopathic macular hole. The roof of the pseudocyst is torn which continues to have traction exerted by the vitreous attachments.
Fig. 3. Stage 3 idiopathic macular hole. The retinal elements have separated apart and the retina has thickened. An operculum is attached to the visible posterior hyaloid face.
Fig. 4. Stage 4 idiopathic macular hole. The posterior hyaloid face is detached off the surface of the retina.
