Blood-retinal barrier permeability and its relation to progression of retinopathy in patients with type 2 diabetes. A four-year follow-up study

Abstract

Abstract. Forty patients with late-onset diabetes (age at diagnosis 30 years or more) and minimal retinopathy as found by fundus photography were followed prospectively by repeated examination (baseline, 1 year, and 4 years). The study shows that early retinopathy changes are not permanent or invariably progressive. In the 1st year of follow-up microaneurysms worsened in 25%, improved in 10%, and remained stabilized in 65%. Vitreous fluorometry was able to detect an overall increase of 0.84_+1.06 x 10 -6 min -1 in blood-retinal barrier (BRB) penetration ratios. After 4 years, 16 of the 40 patients had undergone photocoagulation (focal photocoagulation in 11 and pan retinal photocoagulation in 5). The eyes that needed photocoagulation were the eyes that had higher fluorometry penetration ratios at the patient's entry into the study and showed a higher rate of deterioration during the 1st year of the study (5.54_+ 1.97 vs 3.11_l.22x10-6min -a, P<0.001, initial values; 1.52_+0.76 vs 0.45+_0.99x10 -6 min -a, P< 0.001, annual increase in leakage). The eyes that did not need photocoagulation, 24 out of 40, showed stable fluorometry readings within the 4-year period of followup (+0.02_+0.98 10 -6 min-1). Abnormally high vitreous fluorometry values and their rapid increase over time appear to be good indicators of rapid progression and worsening of the retinopathy.

Progression of retinopathy and alteration of the blood-retinal barrier in patients with type 2 diabetes: a 7-year prospective follow-up study

“…A first report published after 4 years of follow-up showed a positive correlation (r 2 = 0.11, P=0.02) between high BRB permeability and development of need for photocoagulation, even among patients with the same retinal morphology [2]. A positive correlation was also registered between fast rates of increase in BRB permeability during the first year of follow-up and future need for photocoagulation (r 2 = 0.13, P=0.001).…”

“…A need for photocoagulation, as determined by pre-established guidelines, was considered a primary outcome indi-cating worsening of the retinopathy. The results of the first 4 years of follow-up have been published [2]. We have now extended the follow-up of the patients to a total of seven 7 years, and the final results are now reported.…”

“…Photocoagulation was performed by the attending ophthalmologist whenever it was considered needed and following Early Treatment Diabetic Retimopathy Study guidelines [2]. Vitreous fluorometry was performed only in patients who had not undergone photocoagulation.…”

“…Scans were taken before the administration of fluorescein and 60 min after injection. Details of the procedure and determination of the vitreous fluorometry penetration ratio (VFPR), which reflects blood-retinal barrier permeability, are described in the previous 4-year report of this study [2]. The normal value of the vitreous VFPR in a series of 22 persons below 60 years is 2.7 0.810 ±6 min ±1 (mean + 2SD, 4.3 10 ±6 min ±1 , upper value of normal range with 95% degree of confidence) [7].…”

“…A solution of 20% sodium fluorescein (14 mg kg body weight) was then injected intravenously. The fluorescein angiography was performed according to a set protocol [2]. Microaneurysms were graded semi-quantitatively into four categories: 0, absent or questionable; 1, one to five microaneurysms; 2, five to ten microaneurysms; 3, more than ten microaneurysms.…”