Passive permeability and outward active transport of fluorescein across the blood-retinal barrier in early ARM

Aim-To study the passive and active transport of fluorescein across the blo od-retina barrier in early age related maculopathy (ARM) (soft drusen > 63 mum, hyperpigmentation and/or hypopigmentation in patients above 50 years o f age). Methods-15 patients and 10 healthy subjects were included. Morphological ch anges were graded from 30 degrees fundus photographs using a simplified ver sion of the epidemiological ARM study group classification system. Differen tial vitreous spectrofluorophotometry was used to assess the transport prop erties of the blood-retina barrier (that is, passive permeability and unidi rectional permeability caused by outward active transport from the vitreous to the blood). Results-The passive permeability of the patient group was not significantly different from that of the control group. Four patients with passive perme ability more than 3 SD above the mean of the control group (mean 1.8 (SD 0. 7) nm/s, range 1.0-3.0 nm/s, data normally distributed) all had centrally l ocated drusen > 500 mum and superjacent pigment clumps of 63-500 mum in dia meter. There was no significant difference between the unidirectional perme abilities for the patient group and for the control group (mean 47.4 (29.3) nm/s, range 12.7-91.1 nm/s). Conclusion-There was no significant difference in the passive permeability and in the unidirectional permeability of fluorescein. However, the study m ay indicate that the combination of very large drusen and superjacent pigme nt clumps in ARM may be associated with a deterioration of the blood-retina barrier.