Influence of cataract light scatters on retinal vessel oxygen saturation

The aim of our study was to compare metabolic (oxygen saturation; %) and anatomical parameters (retinal vessel diameter; μm) of retinal vessel oximetry (RO) in patients with cataract formation against those of healthy controls with clear lenses.

A total of 96 eyes of 62 subjects were examined: 51 eyes from 33 cataract patients (mean age: 64.8y) were compared to 45 eyes from 29 controls with clear lenses (mean age: 61.5y). RO was performed with the oxygen saturation measurement tool from the RVA (IMEDOS Systems UG). The oxygen saturation in all major peripapillary retinal arterioles (A-SO₂ ) and venules (V-SO₂ ) was measured, and their difference (A-V SO₂ ) was calculated. In addition, the corresponding diameter in retinal arterioles (D-A) and venules (D-V) was evaluated. Cataract formation was graded according to the Lens Opacities Classification System III (LOCS III). Oximetry data were compared with the grade of cataract formation within both groups. For statistical evaluation, anova-based linear mixed-effects models were calculated (spss^® , pairwise comparisons: Bonferroni-corrected; p < 0.05).

Cataract eyes showed significantly lower A-SO₂ and A-V SO₂ values (mean ± SD 92.52 ± 9.80% and 28.56 ± 9.80%), when compared to healthy controls (95.47 ± 4.48% and 34.8 ± 7.08%; p = 0.046 and p = 0.001). Within the cataract group, cortical opacities showed significant interactions with the A-SO₂ , V-SO₂ and the A-V SO₂ parameters (p = 0.027; p = 0.002; and p = 0.026, respectively).

These data indicate that the cataract-induced light scatter influences optical retinal oxygen measurements. Cortical opacities showed the highest influence on RO measurement when compared to nuclear opacification, nuclear colour and posterior cataract formation.