Hemoglobin oxygen saturation in myopic eyes: a scanning laser ophthalmoscope study

AIM: To evaluate retinal hemoglobin oxygen saturation in myopic eyes by scanning laser ophthalmoscope (SLO) and to assess its correlations with different severity of myopia. METHODS: Sixty-one eyes from 61 patients were included and subdivided into three groups according to their refractive errors: high myopia group [20 eyes, spherical equivalent (SE)≤-6 D]; low and moderate myopia (22 eyes, -6.0<SE≤-0.5 D); normal (19 eyes, -0.5<SE<+0.5 D). All subjects underwent SLO imaging with dual lasers (532 nm and 633 nm). The oxygen saturations of hemoglobin in arteries (SO2A) and veins (SO2V), and their differences (SO2AV) were estimated from the optical densities of the vessels on the images at the two wavelengths. Pearson’s or Spearman’s rank correlation coefficient were calculated to assess the correlation between retinal hemoglobin oxygen saturation and refractive error/axial length (AL). RESULTS: For the retinal oxygen saturation, the SO2V in high myopia group (73.21%±21.42%) was significantly higher than that in normal group (55.81%±21.69%) and low and moderate myopia group (56.88%±13.83%, P<0.05). The SE was significantly correlated with SO2A (r=-0.30) and SO2V (r=-0.36; P<0.05), and AL was also significantly correlated with SO2A (r=0.27) and SO2V (r=0.30; P<0.05). No significant correlations were found between SO2AV and SE and AL (P>0.05). CONCLUSION: SO2A and SO2V increased in more myopic eye based on SLO measurements. Further studies are warranted to investigate the changes of retinal hemoglobin oxygen saturation in myopia with different methods.