Diabetic macular oedema: a comparison of vitreous fluorometry, angiography, and retinopathy

Abstract

Aim: To evaluate the relation between the quantitative measurement of vitreous fluorescein with fluorescein angiography and retinopathy in diabetic patients with and without clinically significant macular oedema (CSMO). Methods: In a prospective cross sectional study, passive permeability and active, outward transport of fluorescein across the blood-retinal barrier were quantitated with vitreous fluorometry in 61 eyes from 48 patients with CSMO and 22 fellow eyes without CSMO, after exclusion of eyes with previous macular laser treatment and vitreous liquification. All patients were recruited from the university hospital's outpatient clinic. Retinopathy and fluorescein angiograms were evaluated on 60 degree photographs. Results: The passive permeability in CSMO was significantly correlated with the severity of leakage on fluorescein angiograms (r=0.73), the level of retinopathy (r=0.61), and visual acuity (r=0.45). Significant differences between eyes with CSMO and eyes without CSMO were found for passive permeability (p<0.001), fluorescein leakage (p<0.001), visual acuity (p=0.02), and retinopathy (p=0.002). Conclusion: Passive permeability of fluorescein quantitated with vitreous fluorometry was correlated both with semiquantitative fluorescein angiography and retinopathy, and a significant increase in passive permeability was found when comparing eyes with CSMO to eyes without CSMO. No such pattern was found for the active transport indicating that passive and not the outward, active transport is the factor of most importance in the development of CSMO. C linically significant macular oedema (CSMO) develops with time in 10-15% of diabetic patients.1 2 The tight blood-retinal barrier is damaged as the result of loss of anchor proteins in tight junctions and trans-endothelial vesicular transport in the capillary endothelial cells and/or the retinal pigment epithelium 3 4 leading to an increase in the passive leakage of water and electrolytes and retinal thickening. Quantifying the passive leakage could be valuable in clinical investigations in addition to semiquantitative photographic techniques and measurements of retinal thickness. Previous studies with vitreous fluorometry have shown an increase in passive permeability both in diabetic retinopathy and macular oedema [5][6][7] ; however, the contribution of retinopathy or oedema has not been analysed.An outward, active transport of fluorescein, inhibited by competitive and metabolic inhibitors, has been demonstrated both in vitro and in vivo. [8][9][10][11] Thus, CSMO could also be related to the metabolic activity of the retinal pigment epithelium as a result of changes in the active transport of electrolytes and water from the retina to the blood. If the active transport decreases, retinal oedema could theoretically appear. In contradiction to this hypothesis a previous study found the active transport to be significantly increased in those with CSMO compared to healthy subjects and nearly unchanged compared to a small number of eyes without CSMO. 12The pur...

Early changes in glomerular size selectivity in young adults with type 1 diabetes and retinopathy. Results from the Diabetes Incidence Study in Sweden

“…The magnitude of retinal leakage of fluorescein correlates with the severity of retinopathy and visual acuity and is more important in macular oedema (Sander et al 2002). In agreement, in our study, patients with maculopathy had the highest urinary levels of IgG2 and IgG2/IgG4 suggesting a widespread capillary damage with a general change in size selectivity of the basements membrane in the capillaries.…”

MRI retinovascular studies in humans: research in patients with diabetes

“…This result indicates that DCE-MRI can detect BRB damage in patients with retinal edema associated with diabetes. Furthermore, these data are consistent with results from previous vitreous fluorophotometry studies that showed significantly greater contrast influx in diabetic patients than in control groups (14)(15)(16). Differences between NCS and CS subgroups that were observed in the vitreous fluorophotometry studies (14)(15)(16) were not found in this study, but this could simply be due to the relatively small sample size of the NCS and CS subgroups.…”

Visual outcome of patients with macular edema after pars plana vitrectomy and indocyanine green-assisted peeling of the internal limiting membrane

“…The reasons discussed for the development of persistent macular edema are diverse. Breakdown of the bloodretinal barrier (BRB) and vitreoretinal traction are probably the most relevant factors [25,30].…”