Iridocorneal endothelial syndrome
Iridocorneal endothelial (ICE) syndrome is a spectrum of disorders characterized by varying degrees of iris changes, pupillary anomalies, structural and proliferative abnormalities of the corneal endothelium, and peripheral anterior synechiae. Three clinical variants of ICE syndrome have been described in the literature. When the disease is confined to the inner corneal surface, corneal edema may occur as a result of subnormal endothelial pump function (Chandler syndrome). When the abnormal endothelium spreads onto the surface of the iris, the resulting contractile membrane may produce iris atrophy, corectopia, and polycoria—hallmarks of essential (progressive) iris atrophy (Fig 6-16). The third variant, Cogan-Reese syndrome (iris nevus syndrome) is characterized by the presence of multiple pigmented iris nodules, which are also produced by the contracting endothelial membrane. The syndrome occurs most commonly in middle-aged women and is almost always unilateral.
Figure 6-16 Iridocorneal endothelial syndrome, essential iris atrophy variant, with corectopia.
(Courtesy of Stephen Orlin, MD.)
The pathogenesis of ICE syndrome is unknown but appears to involve abnormal cloning of endothelial cells, which take on the ultrastructural characteristics of epithelial cells (“ICE cells”). It is not clear when the abnormal cloning occurs, however. Herpesvirus may be causative, as viral DNA has been identified in some corneal biopsy specimens following keratoplasty and in the aqueous humor of some ICE patients. ICE cells seen with specular microscopy are typically abnormal, large, rounded, and pleomorphic. They show a characteristic reversal of the normal “light-dark” pattern; thus, the surface appears dark with an occasional central light spot, and the intercellular borders appear light. In vivo confocal microscopy shows ICE cells to be pleomorphic epithelial-like endothelial cells with hyperreflective nuclei and cell borders that appear brighter than cell surfaces.
Varying degrees of progressive endothelialization take place in the cornea, in the anterior chamber angle, and on the iris surface. Gonioscopy demonstrates broad-based iridotrabecular synechiae, which are due to the proliferation and migration of abnormal endothelium over the anterior chamber angle and which result in outflow obstruction and secondary glaucoma. Ultrasound biomicroscopy (UBM) is useful for detecting changes in angle structures in ICE syndrome, especially in the presence of corneal edema that does not allow visualization with gonioscopy.
The differential diagnosis of ICE syndrome should include asymmetric posterior polymorphous dystrophy and other causes of unilateral corneal edema.
Treatment options for the corneal component of this syndrome are penetrating keratoplasty and endothelial keratoplasty. Treatment of the glaucoma can be challenging, as filtering surgery may fail because of the progressive growth of the abnormal endothelial membrane extending over the trabecular meshwork and filtration site. Implanted tube shunts may overcome regrowth of the membrane in the filtration site. Long-term graft clarity depends on the successful control of intraocular pressure, which can be difficult (see BCSC Section 10, Glaucoma). Definitive keratoprosthesis may be an alternative to repeated traditional keratoplasty.
Carpel EF. Iridocorneal endothelial syndrome. In: Mannis MJ, Holland EJ, eds. Cornea. Vol 1. 4th ed. Philadelphia: Elsevier; 2017:844–855.
Phillips DL, Goins KM, Greiner MA, Alward WL, Kwon YH, Wagoner MD. Boston type 1 keratoprosthesis for iridocorneal endothelial syndromes. Cornea. 2015;34(11): 1383–1386.
Quek DT, Wong CW, Wong TT, et al. Graft failure and intraocular pressure control after keratoplasty in iridocorneal endothelial syndrome. Am J Ophthalmol. 2015;160(3): 422–429.e1.
Sacchetti M, Mantelli F, Marenco M, Macchi I, Ambrosio O, Rama P. Diagnosis and management of iridocorneal endothelial syndrome. Biomed Res Int. 2015;2015:763093.
Peripheral cornea guttae
Peripheral cornea guttae (Hassall-Henle bodies) are small wartlike excrescences that appear in the peripheral portion of the Descemet membrane. A normal change with aging, they result from thickening of the Descemet membrane, which takes place throughout life, and occur on the posterior part of the membrane, protruding toward the anterior chamber. With the slit lamp, Hassall-Henle bodies have the appearance of small, dark dimples within the endothelial mosaic; these are best seen by specular reflection. Rarely seen before age 20 years, Hassall-Henle bodies then increase steadily in number with age. When they appear in the central cornea, they are pathologic and are called cornea guttae. Central cornea guttae associated with progressive stromal and eventually epithelial edema represent Fuchs endothelial corneal dystrophy (see Chapter 7).