Abstract
Purpose:
To investigate the relationship between retinal vascular oxygenation with visual field loss and retinal nerve fibre layer defects in subtypes of glaucomatous eyes with asymmetrical hemispheric visual field loss.
Methods:
This was a prospective comparative study conducted at the Singapore National Eye Centre. Patients with glaucoma, who preferably had asymmetrical visual field loss, were recruited. All patients underwent retinal oxygenation and vessel calibre measurements by Oxymap T1 (Oxymap, Reykjavik, Iceland) and a SD-OCT (Cirrus, Carl Zeiss Meditec, Dublin, CA) scan. All patients also underwent a complete ophthalmic and medical history taking and physical examination. For comparison among different subtypes of glaucoma, an analysis of variance (ANOVA) with Bonferroni method for multiple comparisons was used. A paired t-test was used to compare the intra-eye differences.
Results:
89 patients (mean age 68.4 ± 9.86 years, 52.8% male, 85.4% Chinese) were included for analysis. 31 patients had Primary Open Angle Glaucoma (POAG), 32 had Primary Angle Closure Glaucoma (PACG) and 26 had Normal Tension Glaucoma (NTG). Compared to POAG and PACG, the visual field defect was milder in NTG when comparing the mean deviation (p<0.05) and AGIS score (p<0.05). Venular SaO2 in NTG was higher for the corresponding most affected visual field quadrant compared to the least affected. (56.36±19.72% vs. 51.23±20.63%, p=0.009) Venular diameter in PACG was higher in the most affected quadrant compared to the least affected. (174.17±21.03μm vs. 137.78±35.44 μm, p<0.001) Apart from that, there were no significant differences in oxygenation when comparing between asymmetrical areas of visual field loss. RNFL thickness in NTG was lower in the more affected hemisphere compared to the less affected hemisphere. (72.38±12.84μm vs. 89.90± 25.00μm, p=0.01) RNFL thicknesses in POAG and PACG tended to be lower in the more affected hemisphere, but did not reach statistical significance. (p=0.19 and p=0.05 respectively)
Conclusions:
Apart from venular SaO2 in NTG, there were no significant differences in retinal oxygenation when comparing between highly asymmetrical areas of visual field loss. Venular diameter in PACG was wider in the most affected quadrant compared to the least affected but not in any other group.
Keywords: 758 visual fields •
635 oxygen