Retinal oximetry in branch retinal vein occlusion

To measure retinal oxygen saturation (SO₂ ) in eyes with branch retinal vein occlusion (BRVO).

Retinal oximetry was performed using the Oxymap T1 retinal oximeter in 50 eyes (50 patients) with resolved BRVO. SO₂ was calculated in each major retinal artery and vein in four quadrants. The superior or inferior hemisphere with BRVO was categorized as the affected hemisphere and the other as the unaffected hemisphere.

Oxymap T1 allowed us to measure SO₂ in major retinal vessels. Both arterial and venous SO₂ in the affected hemisphere were significantly higher than those in the unaffected hemisphere. However, there was no significant difference in arteriovenous (A-V) difference in SO₂ between the affected and unaffected hemispheres. Of the 50 included eyes, 32 had non-ischemic BRVO and 18 had ischemic BRVO. In the affected hemisphere, arterial SO₂ was significantly higher in ischemic BRVO (106.9 ± 8.8%) than in non-ischemic BRVO (101.3 ± 9.2%, p = 0.044). There were no significant differences in venous SO₂ between non-ischemic and ischemic BRVO. Consequently, the A-V difference in SO₂ was significantly higher in ischemic BRVO (51.9 ± 13.9%) than in non-ischemic BRVO (43.4 ± 11.5%, p = 0.028). In multiple regression analysis, the type of perfusion (non-ischemic or ischemic) had associations with arterial SO₂ (β = 0.365, p = 0.013) and with A-V differences in SO₂ in the affected hemisphere (β = 0.406, p = 0.006).

In ischemic BRVO, arterial SO₂ and the A-V difference in SO₂ in the affected hemisphere were significantly higher than in non-ischemic BRVO.