视网膜血氧饱和度检测仪在眼部应用的研究进展

视网膜血氧饱和度检查是一种快速、无创的新型视网膜血管成像技术,可测量视网膜主要动脉及静脉的血氧饱和度并进行量化分析,可应用于视网膜动脉阻塞、视网膜静脉阻塞、糖尿病视网膜病变、老年性黄斑变性及青光眼等许多眼科疾病的诊断及随访,可有助于加深疾病的病因及发病机制的理解,并应用于疾病病情的评估及预后分析,是现有影像检查设备的重要补充.     

Reproducibility of retinal vessel oxygen saturation measurements in healthy young subjects

Purpose: An adequate oxygenation and perfusion is essential for the function of the inner retina. Recently, several techniques for the measurement of retinal oxygen saturation became available. We set out to evaluate reproducibility of the measurements using a modified Retinal Vessel Analyzer. Methods: A total of 20 healthy female and male subjects aged between 18 and 35 years (22.9 ± 3.9; mean ± SD) were included. The measurement of retinal oxygen saturation with the retinal oximeter employed in this study is based on optical reflectometry using the different absorption characteristics of oxygenated and deoxygenated haemoglobin. The intraclass correlation coefficients and the coefficients of variation (CV) for test–retest, short‐term as well as day‐to‐day measurements were calculated. Results: The intraclass correlation coefficients were between 0.91 and 0.94 for retinal branch arteries and between 0.84 and 0.88 for retinal branch veins. In retinal arteries, we calculated a test–retest CV of 3.24 ± 3.18% for oxygen saturation measurements. In retinal veins, data were slightly less reproducible with a CV of 4.92 ± 3.57%. Short‐term reproducibility of both measurement cycles on each study day was in the same range (CV in retinal arteries: 2.91 ± 2.42% and CV in retinal veins: 4.76 ± 3.14%). The day‐to‐day coefficient of variation was slightly higher (CV in retinal arteries: 3.97 ± 2.87% and CV in retinal veins: 6.18 ± 3.36%). Conclusion: The reproducibility of haemoglobin oxygen saturation measurements using the retinal oximeter is acceptable. Further studies on the validity of the obtained results are, however, required.     

Reliability and Reproducibility of Retinal Oxygen Saturation Measurements using a Predefined Peri‐papillary Annulus

Purpose: To determine the reliability and reproducibility of the Vesselmap Oximetry Module for arteriolar and venular oxygen saturation (SO₂) of the same retinal area, specified by a peripapillary annulus, in healthy subjects. Methods: Fundus oximetry images were obtained, using a standardized protocol by a single observer, from the right eye of 20 healthy individuals. Age range was 19–45 years old, and images were analysed using the oximetry module of the Vesselmap System (Imedos, UG, Germany). Intra‐observer reliability (assessment of two measurements of SO₂ values performed 5 days apart); interobserver reliability (assessment of SO₂ performed by two different trained observers); and intrasubject reproducibility (comparison of SO₂ measurements of two different images of the same subject and retinal area, taken 10 min apart) were assessed. The standard deviations between the repeated measurements (SDr), together with the intraclass correlation coefficient (ICC), of these three parameters were calculated. Results: The SDr for intra‐observer reliability was 0.56% and 0.55% for arteriolar and venular SO₂, respectively. The results were similar for intrasubject reproducibility (0.69% and 0.79% for arteriolar and venular SO_2, respectively); interobserver reliability, however, was higher (SDr 1.22% and 1.01% for arteriolar and venular SO₂, respectively). The ICC values for intra‐observer reliability were 0.99 for both arteriolar and venular SO₂. The results were similar for both interobserver reliability (0.94 for arteriolar SO₂ and 0.96 for venular SO₂) and intrasubject reproducibility (0.98 for both arteriolar and venular SO₂). Conclusion: Retinal oxygen saturation values taken using the oximetry module of the Vesselmap System are highly reliable and reproducible, provided the image quality is standardized, the same measurement area is analysed in each image, and the number of observers analysing the images is kept to a minimum.     

Retinal vessel oxygen saturation in healthy subjects and early branch retinal vein occlusion

AIM: To measure the retinal oxygen saturation in healthy subjects and early branch retinal vein occlusion (BRVO) in Chinese population. METHODS: The retinal vessel oxygen saturation of the healthy subjects and BRVO patients were measured by a noninvasive retinal oximeter (Oxymap ehf., Reykjavik, Iceland). RESULTS: The study included 22 patients with unilateral BRVO (mean age: 55.1±8.8y) in the study group and 91 healthy participants (mean age: 37.5±14.0y) in the control group. In the healthy individuals, mean arterial and venous oxygen saturation were significantly (P<0.001) higher in the superior nasal quadrant (98.5%±10.1% and 57.3%±8.7%, respectively) than in the inferior nasal quadrant (94.2%±9.0% and 54.1%±9.6%, respectively), followed by the superior temporal quadrant (89.1%±10.1% and 51.9%±8.9%, respectively) and the inferior temporal quadrant (86.4%±9.4% and 46.6%±9.6%, respectively). In patients with ischemic BRVO, arterial oxymetric values were significantly higher and venous measurements significantly lower for the affected vessel (107.5%±9.7% and 46.4%±14.2%, respectively) than the unaffected vessel in the same eye (99.2%±12.2% and 55.5%±7.9%, respectively) and as compared to the vessel in the unaffected fellow eye (93.1%±6.9% and 55.7%±6.8%) (P=0.005 and P=0.02, respectively). In the patients with non-ischemic BRVO, mean venous oxygen saturation was lower in the affected vein (39.8%±12.2%) than in the unaffected vessels of the same eye (50.8%±10.5%) and in the fellow eye (58.21%±5.7%) (P=0.03). Mean arterial oxygen saturation did not differ significantly (P=0.42) between all three groups. CONCLUSION: In patients with BRVO, the venous oxygen saturation in the affected vessels is decreased potentially due to decreased blood velocity and flow. Interestingly, the arterial oxygen saturation in eyes with ischemic BRVO is increased in the affected arteries.     

正常人群视网膜血氧饱和度的测量

目的 测量正常人群中的视网膜血氧饱和度。设计 观察性横断面研究。研究对象 纳入的正常受试者91例,其中男性37例,女性54例,平均年龄（37.5±14.0）岁。方法 对所有受试者进行全身及眼科检查,并采用视网膜血氧仪（Oxymap）测量视网膜血氧饱和度。选取鼻上、鼻下、颞上及颞下象限来分别进行视网膜血氧含量的测量,测量范围为距视盘边缘0.5个直径至3个视盘直径之间,选取象限内最粗的动脉和静脉。将视网膜动、静脉血氧饱和度作为因变量,眼部参数及全身系统性参数作为自变量进行多因素线性回归,分析视网膜动、静脉血氧饱和度与全身因素及眼部指标之间的相关性。主要指标 视网膜平均动脉血氧饱和度（SaO2-A）,视网膜平均静脉血氧饱和度（SaO2-V）,视网膜平均动静脉血氧饱和度差值（SaO2-AV）。结果 中国正常人群的视网膜平均SaO2-A为（92.1±7.2）%;视网膜平均SaO2-V为（52.5±6.6）%;视网膜平均SaO2-AV为（39.6±7.5）%。鼻上象限的SaO2-A、SaO2-V和SaO2-AV较高,分别为（98.5±10.1）%、（57.3±8.7）%和（41.3±11.9）%。在多因素分析中,与SaO2-A相关的系统性因素包括高龄（B=0.24,P=0.049）,高脂血症（B=0.26,P=0.018）。吸烟与SaO2-V的降低有一定的相关性（B=-0.25,P=0.033）;SaO2-V与年龄（P=0.665）、眼压（P=0.073）、舒张压（P=0.616）无显著相关性。SaO2-AV与年龄呈正相关（B=0.219,P=0.046）,与性别成负相关（B=-0.253,P=0.019）。结论 高龄人群的视网膜动脉血氧含量相对较高;吸烟可能会导致视网膜静脉血氧含量降低;视网膜动静脉血氧饱和度差值与年龄呈正相关;男性的视网膜动静脉血氧饱和度差值较大。（眼科,2016, 25： 339－342）     

Oxygen saturation in branch retinal vein occlusion

Purpose: The aim of this study was to test whether oxygen saturation in retinal blood vessels is affected by branch retinal vein occlusion (BRVO). Methods: The spectrophotometric retinal oximeter is based on a fundus camera. It simultaneously captures images of the retina at 586 and 605 nm and calculates optical density (absorbance) of retinal vessels at both wavelengths. The ratio of the two optical densities is approximately linearly related to haemoglobin oxygen saturation. Relative oxygen saturation was measured in retinal blood vessels in 24 patients with BRVO. Friedman’s test and Dunn’s post test were used for statistical analyses. Results: Oxygen saturation in occluded venules ranged from 12% to 93%. The median oxygen saturation was 59% (range 12–93%, n = 22) in affected retinal venules, 63% (23–80%) in unaffected venules in the BRVO eye and 55% (39–80%) in venules in the fellow eye (p = 0.66). Corresponding values for arterioles were 101% (89–115%, n = 18), 95% (85–104%) (p < 0.05) and 98% (84–109%). Conclusions: Venular saturation in BRVO is highly variable between patients. Hypoxia is seen in some eyes but not in others. This may reflect variable severity of disease, degree of occlusion, recanalization, collateral circulation, tissue atrophy, arteriovenous diffusion or vitreal transport of oxygen.     

Reproducibility of peripapillary retinal nerve fiber layer thickness measurements with cirrus HD-OCT in glaucomatous eyes

AIM: To assess the reproducibility of Cirrus high-definition optical coherence tomography (HD-OCT; Carl Zeiss Meditec, Dublin, CA, USA) for analysis of peripapillary retinal nerve fiber layer (RNFL) thickness in glaucomatous eyes METHODS: Forty-five eyes (one eye from each glaucomatous patient) were imaged with Cirrus HD-OCT. Each eye was imaged three times by two separate operators. Intraclass correlation coefficient (ICC), coefficient of variation (CV), and test-retest variability were evaluated for both intraobserver and interobsever measurements RESULTS: In intraobserver measurements, the average RNFL thickness ICC was 0.983. CV and test-retest variability were 2.3% and 4.4 μm respectively. In quadrants ICC ranged from 0.886 to 0.956, the lowest associated with nasal quadrant and CV ranged from 3.6% to 7.7%. In interobsever measurements, the average RNFL thickness ICC was 0.979. CV and test-retest variability were 2.4% and 4.5 μm respectively. In quadrants ICC ranged from 0.886 to 0.957, the lowest associated with nasal quadrant and CV ranged from 3.8% to 8.6%. CONCLUSION: The reproducibility of Cirrus OCT for RNFL thickness is sufficiently good to be useful clinically as a measure of glaucoma progression.     

Reproducibility of retinal nerve fiber layer measurements across the glaucoma spectrum using optical coherence tomography

Purpose:

The purpose was to determine intra-session and inter-session reproducibility of retinal nerve fiber layer (RNFL) thickness measurements with the spectral-domain Cirrus optical coherence tomography (OCT)^® (SD-OCT) in normal and glaucomatous eyes, including a subset of advanced glaucoma.

Materials and Methods:

RNFL measurements of 40 eyes of 40 normal subjects and 40 eyes of 40 glaucomatous patients including 14 with advanced glaucoma were obtained on the Cirrus OCT^® (Carl Zeiss Meditec, Dublin, CA, USA) five times on 1-day (intra-session) and on five separate days (inter-session). Intraclass correlation coefficient (ICC), coefficient of variation (COV), and test-retest variability (TRT) values were calculated for mean and quadrant RNFL in each group separately. Reproducibility values were correlated with age and stage of glaucoma.

Results:

For intra-session reproducibility, the ICC, COV, and TRT values for mean RNFL thickness in normal eyes were 0.993, 1.96%, and 4.02 µm, respectively, 0.996, 2.39%, and 3.84 µm in glaucomatous eyes, and 0.996, 2.41%, and 3.70 µm in advanced glaucoma. The corresponding inter-session values in normal eyes were 0.992, 2.16%, and 4.09 µm, 0.995, 2.62%, and 3.98 µm in glaucoma and 0.990, 2.70%, and 4.16 µm in advanced glaucoma. The mean RNFL thickness measurements were the most reproducible while the temporal quadrant had the lowest reproducibility values in all groups. There was no correlation between reproducibility and age or mean deviation on visual fields.

Conclusions:

Peripapillary RNFL thickness measurements using Cirrus OCT^® demonstrated excellent reproducibility in normal and glaucomatous eyes, including eyes with advanced glaucoma. Mean RNFL thickness measurements appear to be the most reproducible and probably represent the best parameter to use for longitudinal follow-up.     

Phenylephrine 5% added to Tropicamide 0.5% eye drops does not influence retinal oxygen saturation values or retinal vessel diameter in glaucoma patients

Purpose: To test whether adding topical phenylephrine 5% to tropicamide 0.5% eye drops in the protocol for pupil dilation affects the retinal vessel oximeter measurements in patients with glaucoma. To test whether phenylephrine 5% has an influence as a vasoconstrictor on the retinal vessel width and can improve the proportion of high‐quality retinal images in patients with glaucoma. Methods: Retinal images of 66 patients with chronic open‐angle glaucoma were obtained before and after the administration of phenylephrine 5% eye drops to patients already dilated with tropicamide 0.5% with the Oxymap Retinal Oximeter (Oxymap ehf, Reykjavik, Iceland). Specialized software, Oxymap Analyzer, analysed the images and measured the oxygen saturation and vessel diameter. Oxygen saturation was measured in first‐ and second‐degree vessels. A Mann–Whitney U‐test was used to compare both groups. Quality of the images was assessed, and a Fisher’s exact test was used to compare the proportion of high‐ and poor‐quality images. Results: There was no significant difference in arterial and venous oxygen saturation in patients with glaucoma whether dilated by tropicamide alone or a combination of tropicamide and phenylephrine (97 ± 6% versus 96 ± 5%, p = 0.88 for arterial saturation and 66 ± 6% versus 67 ± 6%, p = 0.78 for venous saturation, n = 27). There was no significant difference in vessel diameter between both conditions for the different vessels (p = 0.61 for arterial saturation and p = 0.51 for venous saturation, n = 27). The proportion of high‐quality images was significantly higher after the combination regimen compared with tropicamide only (p = 0.0001). Conclusion: The addition of topical phenylephrine 5% after tropicamide 0.5% improved the proportion of high‐quality retinal oximetry images without influencing the retinal oxygen saturation values or the retinal vessel diameter in patients with glaucoma.     

Study of retinal vessel oxygen saturation in ischemic and non-ischemic branch retinal vein occlusion

AIM: To explore how oxygen saturation in retinal blood vessels is altered in ischemic and non-ischemic branch retinal vein occlusion (BRVO). METHODS: Fifty BRVO eyes were divided into ischemic (n=26) and non-ischemic (n=24) groups, based on fundus fluorescein angiography. Healthy individuals (n=52 and n=48, respectively) were also recruited as controls for the two groups. The mean oxygen saturations of the occluded vessels and central vessels were measured by oximetry in the BRVO and control groups. RESULTS: In the ischemic BRVO group, the occluded arterioles oxygen saturation (SaO2-A, 106.0%±14.3%), instead of the occluded venule oxygen saturation (SaO2-V, 60.8%±9.4%), showed increases when compared with those in the same quadrant vessels (SaO2-A, 86.1%±16.5%) in the contralateral eyes (P<0.05). The oxygen saturations of the central vessels showed similar trends with those of the occluded vessels. In the non-ischemic BRVO group, the occluded and central SaO2-V and SaO2-A showed no significant changes. In both the ischemic and non-ischemic BRVOs, the central SaO2-A was significantly increased when compared to healthy individuals. CONCLUSION: Obvious changes in the occluded and central SaO2-A were found in the ischemic BRVO group, indicating that disorders of oxygen metabolism in the arterioles may participate in the pathogenesis of ischemic BRVO.