Reproducibility of retinal oxygen saturation in normal and treated glaucomatous eyes.

AIM

To measure the reproducibility of retinal oxygen saturation (SaO2) levels among treated glaucomatous eyes and normal controls in a prospective non-randomised study.

METHODS

Patients with perimetric glaucoma (PG) and normal controls were included. Exclusion criteria for both groups included visual acuity <20/30, unreliable visual fields, thyroidopathies, hemoglobinopathies, cardiovascular and pulmonary diseases. Retinal oximetry was performed twice consecutively on one randomly selected eye of PG and normal controls using spectrophotometric retinal oximeter (SRO; Oxymap ehf., Iceland). Four main retinal vessel pairs were analysed separately. Coefficients of variability (CoV), coefficients of repeatability (CoR) and intraclass correlation coefficients (ICCs) in arteries (a.SaO2) and veins (v.SaO2) were calculated.

RESULTS

23 PG (mean age 68.3±10.8 years) and 22 normal subjects (mean age 61.5±18.2 years; p=0.14) were included. The intraocular pressure and mean ocular perfusion pressure in glaucoma (14.4±4.2 mm Hg; 45.8±5.8 mm Hg) and controls (14.3±3.3 mm Hg; 45.8±6.1 mm Hg) were similar (p >0.05). In the PG group, the a.SaO2 had a CoV of 1.6%, a CoR of 4.7 and an ICC of 0.97; the v.SaO2 had a CoV of 5.9%, a CoR of 8.7 and an ICC of 0.96. In normals, the a.SaO2 had a CoV of 0.98%, a CoR of 3.3 and an ICC of 0.97; the v.SaO2 had a CoV of 4.8%, a CoR of 7.7 and an ICC of 0.93.

CONCLUSIONS

Retinal oximetry measurements using SRO are highly reproducible in both treated glaucomatous and normal eyes.