Bilateral Fuchs’ Heterochromic Iridocyclitis In A Patient With Progressive Keratoconus: A Rare And Clinically Significant Association

To report a rare coexistence of bilateral Fuchs’ Heterochromic Iridocyclitis (FHI) and progressive keratoconus, highlighting diagnostic challenges and implications for corneal cross-linking (CXL).

Tertiary referral centre.

A 26-year-old patient presented with progressive visual deterioration and ocular discomfort in both eyes. Initial evaluation (2020) demonstrated papillary conjunctivitis, prominent corneal nerves, inferior incomplete Fleischer ring, and compound myopic astigmatism. Corneal tomography confirmed keratoconus.

Four years later, the patient reported worsening visual acuity. Best corrected visual acuity measured 20/50 (20/40) OD and 20/60 (20/25) OS. Scheimpflug tomography revealed significant ectatic progression with borderline pachymetry (387 µm) and increase in Kmax from 50.6 D to 54.9 D in the right eye. Corneal cross-linking was scheduled.

Preoperative slit-lamp examination identified diffuse stellate keratic precipitates and mild anterior chamber activity, prompting deferral of surgery. Uveitis evaluation established a diagnosis of FHI. A history of psoriasis was elicited. Following topical anti-inflammatory therapy and quiescence of inflammation, hypotonic CXL was performed successfully in the right eye. Subsequent follow-up demonstrated bilateral features consistent with FHI.

FHI is characteristically unilateral; bilateral involvement is uncommon and may indicate a more aggressive inflammatory phenotype. The coexistence of bilateral FHI and keratoconus is exceptionally rare. Shared neural crest embryological origins of the corneal stroma, iris stroma, and uveal melanocytes may suggest a biologically plausible association. This case underscores the necessity of meticulous anterior segment evaluation prior to CXL, as unrecognized low-grade uveitis may influence surgical timing, safety, and outcomes.