Iridocorneal Endothelial (ICE) Syndrome is a progressive, rare eye disorder affecting the cornea, the iris, and the anterior chamber angle, the eye’s natural drainage system. This condition is characterized by the abnormal change and proliferation of corneal endothelial cells, resulting in structural damage and functional impairment of the eye’s anterior structures. ICE Syndrome is typically unilateral, affecting only one eye, and is most frequently diagnosed in young to middle-aged adults, particularly women between the ages of 20 and 50. While the exact cause remains unknown, it is considered a sporadic, acquired disorder rather than a hereditary one.
The Underlying Cellular Problem
The core issue in Iridocorneal Endothelial Syndrome involves the corneal endothelial cells, which form a single, non-regenerating layer on the back surface of the cornea. This layer primarily functions as a pump, actively removing fluid from the corneal tissue to maintain its clarity and prevent swelling. In ICE Syndrome, these endothelial cells undergo an abnormal transformation, acquiring characteristics similar to epithelial cells.
These transformed cells proliferate and migrate beyond their normal boundary, spreading across the trabecular meshwork and the surface of the iris. This migration forms a pathological membrane that compromises the cornea’s ability to regulate fluid. The presence of this membrane and the reduced function of the abnormal cells lead to corneal edema (swelling), which causes blurred vision.
The abnormal membrane also contracts, pulling on the iris tissue. This contraction causes distortion of the pupil and the formation of adhesions, known as peripheral anterior synechiae, between the iris and the cornea. The combination of abnormal cell migration and membrane contraction creates the distinct structural problems seen in the various forms of ICE Syndrome.
Types of ICE Syndrome and Their Appearance
ICE Syndrome is a spectrum of three clinical variations, all sharing the same underlying endothelial cell pathology. The primary differences between them are the degree of corneal swelling versus iris damage.
Chandler Syndrome
This is the most common variant, accounting for approximately 50% of all ICE cases. It is characterized predominantly by corneal edema, which often causes blurred vision, particularly in the morning. Iris changes are typically minimal or mild.
Essential Iris Atrophy
This variation is defined by the most severe changes to the iris structure. Progressive, full-thickness loss of iris tissue leads to the formation of holes (polycoria) and significant displacement of the pupil (corectopia). These dramatic iris defects can cause severe light sensitivity and glare.
Cogan-Reese Syndrome
This subtype is distinguished by the presence of pigmented, nodular lesions on the iris surface. These small nodules are composed of iris-like tissue and are covered by the abnormal endothelial membrane. The characteristic feature is the presence of these distinct iris nodules.
Addressing the Glaucoma Complication
Secondary glaucoma is a serious and frequent complication of ICE Syndrome, occurring in about half of all affected patients. This glaucoma develops when the abnormal endothelial membrane spreads over and obstructs the trabecular meshwork, the eye’s primary drainage structure. The blockage prevents the proper outflow of aqueous humor, causing a dangerous increase in intraocular pressure (IOP).
This pressure elevation poses a direct threat to the optic nerve, which can lead to irreversible vision loss. Glaucoma associated with ICE Syndrome is challenging to control because the underlying pathology is a physical obstruction of the drainage angle. Standard initial treatment involves topical medications, such as aqueous suppressants, to reduce fluid production within the eye.
However, medication efficacy is often limited long-term, and laser procedures like trabeculoplasty are generally ineffective due to the physical blockage. When eye drops fail to sufficiently lower the IOP, incisional surgery becomes necessary to create an alternative drainage pathway. Common surgical options include trabeculectomy, often performed with antifibrotic agents, or the implantation of glaucoma drainage devices, such as tube shunts.
Surgical Options for Tissue Repair
Surgical intervention is often required to repair the physical damage to the cornea and iris caused by the abnormal endothelial cells. For patients suffering from corneal edema, which causes blurred vision, endothelial keratoplasty is performed. This surgery selectively replaces the diseased endothelial layer with a healthy donor layer, restoring the cornea’s pumping function and its clarity.
Two common forms of this procedure are Descemet’s Stripping Endothelial Keratoplasty (DSAEK) and Descemet’s Membrane Endothelial Keratoplasty (DMEK). DMEK offers faster visual recovery, but DSAEK may be preferred if the patient has significant iris changes or extensive adhesions that complicate the procedure. These modern techniques have largely replaced older, full-thickness corneal transplants for ICE-related corneal edema.
Surgical correction also addresses the significant iris damage seen in Essential Iris Atrophy and Cogan-Reese Syndrome. For cases with a severely distorted pupil, pupilloplasty can be performed to reshape the pupil and reduce glare. If the iris has extensive tissue loss or large holes, an artificial iris implant may be used to improve both the cosmetic appearance and the functional light control of the eye.