title: The effect of pars plana vitrectomy and nuclear cataract on oxygen saturation in retinal vessels, diabetic and non-diabetic patients compared.
abstract: OBJECTIVE
  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 ± 2.9% at baseline to 96.6 ± 3.4% at week 7 and 97.3 ± 3.4% at week 52 (p < 0.0001; Friedman test). Vein saturation also increased significantly from 63.5 ± 7.9% at baseline to 66.1 ± 7.7% and 67.0 ± 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 ± 7.5% at baseline to 30.5 ± 7.5% and 30.3 ± 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.
  
  
  CONCLUSIONS
  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.
authors: Department of Ophthalmology, University Hospital and Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
authors: Martin
authors: M
authors: Šín
authors: Department of Ophthalmology, University Hospital and Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
authors: Oldřich
authors: O
authors: Chrapek
authors: Department of Ophthalmology, University Hospital and Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
authors: Marta
authors: M
authors: Karhanová
authors: Department of Ophthalmology, University Hospital and Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
authors: Irena
authors: I
authors: Šínová
authors: TANA Ophthalmology Clinic, Olomouc, Czech Republic.
authors: Kareřina
authors: K
authors: Špačková
authors: Department of Medical Biophysics, Faculty of Medicine and Dentistry, Institute of Molecular and Translational Medicine, Palacky University, Olomouc, Czech Republic.
authors: Kateřina
authors: K
authors: Langová
authors: Department of Ophthalmology, University Hospital and Faculty of Medicine and Dentistry, Palacky University, Olomouc, Czech Republic.
authors: Jiří
authors: J
authors: Řehák
mesh_terms: D000368:Aged; D002386:Cataract / Q000151:congenital* / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000503:physiopathology*; D005260:Female; D006801:Humans; D019654:Lens Implantation, Intraocular; D008269:Macular Edema / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010092:Oximetry; D010100:Oxygen / Q000097:blood*; D018918:Phacoemulsification; D011446:Prospective Studies; D019591:Pseudophakia / Q000503:physiopathology; D015861:Retinal Neovascularization / Q000503:physiopathology*; D012171:Retinal Vessels / Q000503:physiopathology*; D014821:Vitrectomy
chemical_list: D010100:Oxygen
keywords: automatic retinal oximetry; cataract; oxygen saturation; pars plana vitrectomy; retinal vessel blood saturation