Abstract
Purpose::
To analyse the effect of increasing the osmotic pressure in plasma on the retinal thickness in significant diabetic macular oedema (CSMO). The primary effect parameter was the retinal thickness (RT) in the peak oedematous field on the retinal maps of the fast module scans of the StratusOCTTM.
Methods::
Randomised, prospective study. On two separate days 14 patients with diabetic CSMO drank a glycerol solution (0.57 g/mL) of 1.5 and 3 mL/kg body weight (maximum 250 mL). RT, plasma osmolality (p-OSM) and glycerol (p-GLY) were monitored at preset time points for the subsequent 180 min. Likewise, the capillary glucose (BG), intraocular pressure (IOP) and systemic blood pressure (BP) were systematically determined.
Results::
P-OSM and p-GLY correlated strongly (r=0.79, p<0.0001). Doubling the glycerol dose nearly doubled the maximal effect on p-OSM as Δ p-OSM increased from 13 (6.5) (mean)(SD) to 23 (6.7) mOsm/L from baseline 300 (4.4) and 302 (8.1) mOsm/L, respectively (p<0.0001).Baseline RT was 377 (73) and 373 (68) µm for the low and high glycerol dose, respectively. By 20 min both doses had caused a decrease of 7 (5 and 8) µm (p=0.001 and p=0.04, respectively). The RT-curves gradually increased again from 30 min towards the baseline value. Neither BG, BP nor IOP interacted significantly with RT.
Conclusions::
Glycerol-induced hyperosmosis transiently reduces the peak RT in diabetic CSMO. No linear relationship was found between the glycerol dose and the effect on RT in contrast to the p-OSM response. We speculate that the rebound phenomenon partly explain these observations.
Clinical Trial::
www.clinicaltrials.gov NCT00333671
Keywords: diabetic retinopathy • edema • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials