PURPOSE: Evaluate whether optic disc edema results in changes in retinal microcirculation. PATIENTS AND METHODS: The study group consisted of 11 patients with unilateral optic disc edema (papilledema). The control group consisted of the healthy eyes of the same 11 patients. Patients underwent non-invasive photo-spectrometric retinal oximetry using Oxymap T1 retinal oximeter (Oxymap, Reykjavik, Iceland). In the eyes of these 11 patients, we examined the diameter of the retinal arteries and veins, arterial and venous blood oxygen saturation, and the difference in oxygen saturation between arterioles and venules (A-V difference). RESULTS: In the papilledema group, the decrease in the retinal arterial diameter was statistically significant (p=0.001). The median diameter of the retinal artery was 11.70 px (IQR 1.47) or after conversion 109.00 µm (IQR 14.00) in the papilledema group and 13.75 px (IQR 1.61) or 128.00 µm (IQR 15.00) in the control group. The increase in the diameter of the retinal veins in the papilledema group was statistically significant (p=0.012), where the median diameter in the papilledema group was 20.88 px (IQR 3.72) or 194.00 µm (IQR 35.00), and in the control group was 18.18 px (IQR 3.60) or 169 µm (IQR 33.00). There was a statistically significant decrease (p<0.001) in the venous saturation in the papilledema group with a median value of 53.16% (IQR 17.38) and 60.02% (IQR 11.98) in the control group. The median of the A-V difference was 51.92 (IQR 15.96) in the papilledema group, resp. 38.49 (IQR 9.75) in the control group and a significant increase in the papilledema group (p<0.001) was reported. CONCLUSION: Automatic retinal oximetry demonstrated changes in the retinal microcirculation in patients with optic disc edema.

• Keywords
• microcirculation, oximetry, papilledema, retina,
• Publication type
• Journal Article MeSH

PURPOSE: The aim of the study was to obtain the values of oxygen saturation in retinal vessels and ophthalmic blood flow parameters in a healthy Caucasian population and assess whether the oximetry parameters are affected by the flow rate or the vascular resistance. METHODS: The spectrophotometric retinal oximetry and colour Doppler imaging (CDI) of retinal vessels were successfully performed with 52 healthy subjects (average age 29.7 ± 5.6 years). The retinal oximeter simultaneously measures the wavelength difference of haemoglobin oxygen saturation in retinal arterioles and venules. The arteriolar and venular saturation in both eyes was measured. The peak systolic (PSV) end diastolic (EDV) velocities, resistive (RI) and pulsatility (PI) indices were obtained for both eyes using CDI in the ophthalmic artery. A paired t-test and two sample t-tests were used for statistical analyses. The correlation was assessed using the Pearson coefficient correlation. RESULTS: The mean oxygen saturation level was 96.9 ± 3.0% for the retinal arterioles and 65.0 ± 5.1% for the retinal venules. The A-V difference was 31.8 ± 4.6%. The mean of the measured haemodynamic parameters was PSV 46.6 ± 9.4 cm/s, EDV 12.0 ± 3.5 cm/s, PI 1.68 ± 0.38 and RI 0.74 ± 0.05. No significant difference in oxygen saturation and haemodynamic parameters was found between the left and the right eyes or the dominant and non-dominant eye. The oximetry and ultrasound values were sex independent. The Pearson correlation coefficient demonstrated a significant yet weak negative correlation between A-V difference and RI (r = -0.321, p = 0.020). CONCLUSIONS: A negative correlation between A-V difference and resistance index was observed, suggesting that reduced oxygen consumption may reflect the increased vascular tone of the ophthalmic vessels, which is likely determined by autoregulatory mechanisms.

• Keywords
• Doppler imaging, automatic retinal oximetry, ophthalmic artery, retinal vessel oxygen saturation,
• MeSH
• Retinal Artery * diagnostic imaging   physiology   MeSH
• Ophthalmic Artery * MeSH
• Adult MeSH
• Hemodynamics MeSH
• Hemoglobins MeSH
• Oxygen MeSH
• Humans MeSH
• Young Adult MeSH
• Oximetry methods   MeSH
• Retina MeSH
• Blood Flow Velocity MeSH
• Oxygen Saturation MeSH
• Healthy Volunteers MeSH
• Check Tag
• Adult MeSH
• Humans MeSH
• Young Adult MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Hemoglobins MeSH
• Oxygen MeSH