ABSTRACT.Purpose: Diabetic retinopathy is characterised by morphological lesions secondary to retinal vascular impairment, and it is assumed that changes in the diameter regulation of retinal arterioles are involved in the disease pathogenesis. It has previously been shown that prostaglandin F2a can constrict retinal arterioles in vitro. In the present study, we investigated whether a similar effect could be achieved by topical administration in diabetic patients with dilated retinal arterioles and retinopathy. Methods: Twenty-two type 1 diabetic patients with mild retinopathy and twenty-four matched normal controls were randomized to topical treatment with the prostaglandin F2a agonist latanoprost twice daily for 1 week, followed by similar treatment with the cyclo-oxygenase inhibitor diclofenac, or to receive the two medications in the reverse order. The Dynamic Vessel Analyzer was used to assess the effect of the interventions on the resting diameter of retinal vessels and on the diameter response of retinal arterioles to increased blood pressure (BP) induced by isometric exercise and flicker stimulation. Results: Latanoprost reduced the resting diameter of retinal arterioles significantly in patients with diabetes (p = 0.01), but had no effect on normal persons. Diclofenac had no effect on the resting diameter of arterioles in either of the groups. The diameter responses to increased BP and flicker stimulation were not significantly changed by any of the treatments. Conclusion: Long-term prospective studies are needed to study the effect of topical treatment with latanoprost on the consequences of retinal hyperperfusion in retinal vascular diseases such as diabetic retinopathy.

Background: Diabetic retinopathy is characterised by morphological lesions in the retina secondary to disturbances in retinal blood flow. Previous studies have shown that the carbonic anhydrase inhibitor (CAI) dorzolamide can induce immediate dilatation of retinal arterioles and a sustained increase in retinal blood flow in primary open-angle glaucoma. However, the effect of sustained treatment with CAI on retinal arterioles in normal persons and in patients with diabetic retinopathy is unknown. Methods: The Dynamic Vessel Analyzer was used to assess the baseline diameter and the diameter response of retinal arterioles during an increase in arterial blood pressure induced by isometric exercise and during flicker stimulation before and 2 h, 24 h and 1 week after onset of topical treatment with dorzolamide. At each examination the diameter responses were studied before and during breathing in of a hypercapnic gas mixture. Results: Treatment with dorzolamide for 1 week significantly increased the diameter of retinal arterioles in normal persons, and breathing in of a hypercapnic gas mixture reduced this response. The pathological vasodilatation and reduced retinal autoregulation in patients with diabetic retinopathy were unaffected by dorzolamide and hypercapnia. Conclusions: The study suggests a lack of relevance of CAI for the treatment of pathological vasodilatation in early diabetic retinopathy.

Purpose: To identify parameters that can predict the postoperative risk for progression of retinopathy to a vision-threatening stage after cataract surgery. This may optimize the timing of surgery and the postoperative follow-up strategy in diabetic patients. Methods: Multi-state survival analysis with death as competing risk was used to investigate how year of onset and age of onset of diabetes, gender, body mass index, HbA1c and blood pressure had affected the risk for developing diabetic macular oedema (DME) and proliferative diabetic retinopathy (PDR) among 2540 right eyes from 2797 diabetic patients operated for cataract on one or both eyes during 25 years until July 1. 2019. Results: Cataract surgery had been performed in 98.8% of patients reaching 90 years of age. The risk for developing both DME and PDR was increased by cataract surgery. The risk was highest during the first postoperative years and increased by preoperative variability in HbA1c. The risk after more than 20 years postoperatively increased by increased cumulative HbA1c pre-operatively. The other studied risk factors contributed differently to the development of the two complications. Conclusions: Decision models for the timing of cataract surgery in diabetic patients should consider that the risk for developing vision-threatening retinopathy depends on follow-up time. Differences in the risk profiles for developing DME and PDR after cataract surgery support that the two complications should be regarded as separate late complications.

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