The histopathology of Fuchs' heterochronic iridocyclitis has been infrequently documented. It is surprising for, in the opinion of some observers, the syndrome constitutes about 2% of all cases of uveitis.1 Its etiology and pathogenesis are largely unknown. It is characterized by unilateral (rarely bilateral) hypopigmentation of the iris, low-grade signs of chronic inflammation in the anterior chamber and vitreous, and, in some cases, cataract and glaucoma.2 The striking transillumination of the iris has been considered to be a secondary manifestation of atrophy and sclerosis of the stroma and of patchy depigmentation of the epithelium.
In large measure, lack of interest in this syndrome has been engendered by the belief that there may be no cause-and-effect relationship between this type of heterochromia and a specific, unique form of uveal inflammation. If true, there would be no reason to consider Fuch's heterochromic iridocyclitis a distinct nosologic entity.3
GOLDBERG MF, EROZAN YS, DUKE JR, FROST JK. Cytopathologic and Histopathologic Aspects of Fuch's Heterochromic Iridocyclitis. Arch Ophthalmol. 1965;74(5):604-609. doi:10.1001/archopht.1965.00970040606004