Abstract
Purpose :
Nocturnal hypotensive insults to the optic nerve are thought to be a mechanism behind normal-tension glaucoma (NTG). There are similarities between the highly vascularised choroid and the corpus cavernosum of the penis. This study investigates whether phosphodiesterase inhibitors can increase bloodflow to the choroid or retina, meeting an unmet need for the treatment of this blinding condition.
Methods :
A prospective imaging study examining eyes before and after a single dose of phosphodiesterase inhibitor (PDE-5i). Male patients currently taking sildenafil or tadalafil for erectile dysfunction underwent ophthalmic examination, intraocular pressure (IOP) and blood pressure/estimated mean arterial pressure (MAP), along with optical coherence tomography angiography (OCTA) before, 1 hour and 2 hours after ingestion. Blood pressure was also checked 1 hour after ingestion. B-scan masks were created to quantify choroidal thickness, OCTA images were binarized to calculate vessel density, and then skeletonised to calculate perfusion density.
Results :
The results report on the right eyes of 15 patients (4 glaucomatous, 11 non-glaucomatous). Mean age (±SD)= 67.9 ± 9.3years, baseline IOP = 12.1 ± 2.8 mmHg, baseline MAP = 95.4 ± 13.6 mmHg. There was a significant increase in choroidal thickness from baseline at 120 minutes (p<0.01). No change in retinal perfusion or vessel density was seen compared to baseline. Mean MAP was significantly reduced by 4.2mmHg (p<0.05) at 60 mins, however no change in IOP was observed to otherwise explain the results.
Conclusions :
These results demonstrate that PDE-5 inhibitors used typically at night for erectile dysfunction may also enhance choroidal bloodflow, giving them the potential to become an investigational treatment in normal-tension glaucoma.
This is a 2020 ARVO Annual Meeting abstract.