Phenylephrine 5% added to Tropicamide 0.5% eye drops does not influence retinal oxygen saturation values or retinal vessel diameter in glaucoma patients

Abstract

. Purpose: To test whether adding topical phenylephrine 5% to tropicamide 0.5% eye drops in the protocol for pupil dilation affects the retinal vessel oximeter measurements in patients with glaucoma. To test whether phenylephrine 5% has an influence as a vasoconstrictor on the retinal vessel width and can improve the proportion of high‐quality retinal images in patients with glaucoma. Methods: Retinal images of 66 patients with chronic open‐angle glaucoma were obtained before and after the administration of phenylephrine 5% eye drops to patients already dilated with tropicamide 0.5% with the Oxymap Retinal Oximeter (Oxymap ehf, Reykjavik, Iceland). Specialized software, Oxymap Analyzer, analysed the images and measured the oxygen saturation and vessel diameter. Oxygen saturation was measured in first‐ and second‐degree vessels. A Mann–Whitney U‐test was used to compare both groups. Quality of the images was assessed, and a Fisher’s exact test was used to compare the proportion of high‐ and poor‐quality images. Results: There was no significant difference in arterial and venous oxygen saturation in patients with glaucoma whether dilated by tropicamide alone or a combination of tropicamide and phenylephrine (97 ± 6% versus 96 ± 5%, p = 0.88 for arterial saturation and 66 ± 6% versus 67 ± 6%, p = 0.78 for venous saturation, n = 27). There was no significant difference in vessel diameter between both conditions for the different vessels (p = 0.61 for arterial saturation and p = 0.51 for venous saturation, n = 27). The proportion of high‐quality images was significantly higher after the combination regimen compared with tropicamide only (p = 0.0001). Conclusion: The addition of topical phenylephrine 5% after tropicamide 0.5% improved the proportion of high‐quality retinal oximetry images without influencing the retinal oxygen saturation values or the retinal vessel diameter in patients with glaucoma.

Peripapillary retinal vessel diameter correlates with mfERG alterations in retinitis pigmentosa

“…Both pupils of each subject were dilated (7.0-8.0 mm) using tropicamide 0.5% and phenylephrine 1% eye drops (Vandewalle et al 2013). After a minimum of 20 minutes, four test-retest fundus images were obtained, as described previously T€ urksever et al 2014, 2015.…”

Retinal vessel diameters decrease with macular ganglion cell layer thickness in autosomal dominant optic atrophy and in healthy subjects

“…According to a previous study (Vandewalle et al 2013), phenylephrine and tropicamide did not have an effect on retinal oxygen saturation or vessel diameters in patients with glaucoma, and therefore, we did not expect them to have an influence on our findings. There was no regulation of caffeine intake during the study, which could have influenced our measurements (Terai et al 2012).…”

Diabetic macular ischaemia is associated with narrower retinal arterioles in patients with type 2 diabetes

“…Retinal vessel vasodilation is known to be impaired in diabetes and prediabetes, and the presence of DMI may be a more severe manifestation of this tendency, leading to narrower arterioles overall in persons with DMI (Lott et al 2013). It is also important to note that our observations are not due to vasoconstriction from topical dilating drops, as these have been found to not influence vessel calibres (Vandewalle et al 2013). Further research on DMI could focus on using other non-invasive haemodynamic measurement techniques (Pemp et al 2013) and measuring vessel calibres at different points in the vascular branching network, which may be differently affected (Torring et al 2014).…”

“…It is also important to note that our observations are not due to vasoconstriction from topical dilating drops, as these have been found to not influence vessel calibres (Vandewalle et al. ). Further research on DMI could focus on using other non‐invasive haemodynamic measurement techniques (Pemp et al.…”