The AVD in oxygen saturation is altered in patients with acute ON. In the early stage of ON, AVD could reflect inflammatory and metabolic changes in the affected eye. Therefore, oximetry could be used as another diagnostic method in MS patients in suspicion of ON. This result would be promising for future investigation in this field.

ABSTRACT.Purpose: To determine the effect of pars plana vitrectomy (PPV) on oxygen saturation in retinal vessels. Methods: We performed a prospective consecutive interventional case series of 20 eyes of 20 patients with macular hole or epiretinal membrane. We performed automatic retinal oximetry (Oxymap Inc., Reykjavik, Iceland) in each patient 24 hr prior to and 45 days (range 42-49) after PPV (classic 20G or sutureless 23G). We analysed oxygen saturations in retinal arteries and veins. Vessel segments of first or second degree were selected. The same segment was analysed before and after PPV. Oximetry data were compared by paired two-tailed t-test. Results: Pars plana vitrectomy did not alter arterial haemoglobin saturation with oxygen (98 ± 2% prior to the surgery and 98 ± 3% after the procedure, p = 0.549). The mean venous haemoglobin saturation with oxygen increased after vitrectomy from 63 ± 10% to 66 ± 8% (p = 0.012). Conclusions: Oxygen saturation is higher in retinal veins after pars plana vitrectomy. Further studies are needed to unveil the mechanism of how vitrectomy affects oxygen metabolism in the retina.

ABSTRACT.Purpose: To determine the effect of pars plana vitrectomy (PPV) on oxygen saturation in retinal vessels in patients with diabetes and non-diabetes after a 1-year follow-up. Methods: This was a prospective consecutive interventional case series in 82 eyes in 82 patients. The sample consisted of 25 patients with non-proliferative diabetic retinopathy with macular oedema based on vitreoretinal traction or epiretinal membrane (ERM) and 57 non-diabetic patients with macular hole and ERM. Automatic retinal oximetry (Oxymap Inc.) was used on all patients 24 hr prior to PPV, and it was also used 7 and 52 weeks after PPV (classic 20G or sutureless 23G). We analysed the data according to subgroup diagnosis and lens status. Results: Arterial saturation increased significantly from 96.4 AE 2.9% at baseline to 96.6 AE 3.4% at week 7 and 97.3 AE 3.4% at week 52 (p < 0.0001; Friedman test). Vein saturation also increased significantly from 63.5 AE 7.9% at baseline to 66.1 AE 7.7% and 67.0 AE 7.2% at weeks 7 and 52 (p < 0.0001; Friedman test). The value of the arteriovenous (A-V) difference decreased significantly after vitrectomy from 32.8 AE 7.5% at baseline to 30.5 AE 7.5% and 30.3 AE 7.0% at weeks 7 and 52 (p < 0.0001; Friedman test). The subgroup analysis revealed that in patients with diabetes, there were no statistically significant changes in oxygen saturation in blood vessels or in the A-V difference after PPV. After vitrectomy, retinal vessel diameter reduced by about 3.5% in both groups of patients. Further, the analysis revealed that opacification of the lens leads to a decrease in oxygen saturation in contrast to a clear lens and pseudophakic IOLs. Conclusion: Oxygen saturation is higher in the retinal veins and arteries after PPV in patients with non-diabetes, and this lasts for at least 52 weeks. In contrast, in patients with diabetes, there is no increase in oxygen saturation in the retinal vessels after vitrectomy. After vitrectomy, retinal vessel diameter reduced in both groups of patients. Further, the nuclear cataract progression has substantial effect on oximetry results. Patients with nuclear cataract exhibited an increase in saturation in both arteries and veins, but the A-V difference remained the same.

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