Purpose: To carry out a longitudinal study of patients with Fuchs' heterochromic uveitis (FHU) in western Sweden and to establish the factors responsible for diagnostic delay.
Methods: A sample of 54 patients, 51 with monocular and three with binocular FHU, were followed for periods ranging from 8 months to 15 years. Firm diagnostic criteria were set. A detailed anamnesis regarding ocular and extraocular symptoms was taken. The eyes were repeatedly examined. Toxoplasma serology was analysed. Complications were noted.
Results: The delay between the first visit to an ophthalmologist and diagnosis was 0-26 years. The most common first symptom was floaters. Iris heterochromia was absent in 11 patients and discrete in 26. Iris atrophy (a diagnostic criterion) was easy to miss. Chorioretinal scars were found in six patients. Toxoplasma serology was positive in 18 (35%) patients. The only serious complication was glaucoma.
Conclusions: The most important reason for delay in diagnosis of FHU is, in our opinion, failure to consider the disease as a diagnosis. This failure may occur because heterochromia is often missing or discrete, iris atrophy is easily overlooked, and vitreous opacities are common, often cause early symptoms and can explain prolonged workup and therapy. A connection with toxoplasmosis in individual cases cannot be excluded but toxoplasmosis cannot be considered a major aetiological factor. If detailed anamnesis is negative and diagnostic criteria are fulfilled, no further workup is required.