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the crystalline lens are also frequently damaged in XFS due to elastosis
[3,4,8,11]. As a consequence, dislocation of the crystalline lens or a previously
implanted artificial intraocular lens (in-the-bag IOL dislocation) is not
uncommon in eyes with XFS. When the crystalline lens is dislocated towards
the anterior chamber, pupillary block and secondary angle closure glaucoma
can develop [13]. Development of nuclear cataract is also typical in XFS [14].
In addition, the disturbance of elastin metabolism diminishes the resistance of
the lamina cribrosa [15, 16]; leads to decreased blood-aqueous barrier function
in the iris, which results in localized vascular occlusions in the anterior iris
layer [17]; and increases the postoperative inflammatory reaction after
extracapsular cataract surgery[14]. However, the most significant complication
of XFS is the development of intraocular pressure (IOP) elevation and XFG,
the most common secondary open-angle glaucoma worldwide [8,18,19].
EXFOLIATIVE GLAUCOMA
XFG develops from XFS, but most XFS eyes do not eventually convert to
XFG. Initially, IOP increases and exhibits high diurnal fluctuation [20]. Later,
mild structural alterations (e.g., retinal nerve fiber layer thinning) become
detectable with imaging devices [20-22]. Ultimately, the increased oxidative
stress in the anterior chamber and pigment liberation from the iris lead to
further, typically very significant IOP elevation, which (in part due to the
elastosis-related weakening of the lamina cribrosa) results in severe
glaucomatous neuroretinal rim damage, increased optic disc cupping, severe
retinal nerve fiber layer loss and severe visual field deterioration, in many
cases already prior to the first ophthalmology visit [18,19,23]. Since the
presence of XFG is frequently unilateral or the severity of glaucomatous
damage is remarkably asymmetrical, most patients do not realize unilateral
visual field deterioration until it becomes very severe, or until the fellow eye
suffers from central visual field deterioration [13,23]. The progression rate of
XFG is almost 3 times faster than that of high-pressure primary open-angle
glaucoma, and 4 times higher than that of normal pressure glaucoma [24,25].