We aim to determine whether lymphatic drainage from the eye changes with age. Using quantitative photoacoustic tomography, groups of young and older mice were studied in the live state. 10 CD-1 mice of 2-3 months (5M/5F) were studied in addition to 13 older mice of 12-13 months (6M/7F). In each of 23 mice, near-infrared tracer (a near-infrared dye, QC-1 conjugated with Bovine Serum Albumin) was injected into the right eye, and imaging of ipsilateral cervical lymph nodes was performed with laser pulses at 11 different wavelengths prior to and 20 min, 2, 4 and 6 h after injection. Mean pixel intensities (MPIs) of nodes were calculated at each imaging session. The areas under the curves (AUC) were calculated for both groups of mice and compared using the t-test. The slopes of MPI of each region of interest were compared using the linear mixed model before and after adjusting for sex, body weight and intraocular pressure of the right eye. The mean intraocular pressure of right eyes before injection was similar in older and younger groups (12.77 ± 2.01 mmHg and 12.90 ± 2.38 mmHg, respectively; p = 0.888). In each mouse, the photoacoustic signal was detected in the right cervical lymph nodes at the 2-h time point following tracer injection into the right eye. At the 4 and 6 h imaging times, a steady increase of tracer signal was observed. Areas under the curve in the right cervical nodes were decreased significantly in older mice compared to younger mice (p = 0.007). The slopes of MPI in the nodes were significantly decreased in old mice compared to young mice both before and after adjusting for sex, body weight and intraocular pressure of the right eye (p = 0.003). In conclusion, lymphatic drainage from the eye is significantly reduced in older eyes. This finding suggests that impaired lymphatic clearance of aqueous humor, proteins and antigens from the eye may contribute to age-related disease of the eye such as glaucoma and inflammatory eye disease.

中文翻译：

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与年龄相关的眼睛淋巴引流下降：一项非侵入性体内光声层析成像研究。

我们旨在确定眼睛的淋巴引流是否随年龄而变化。使用定量光声层析成像，研究了成年和成年小鼠的成活状态。除13只12-13个月的大龄小鼠（6M / 7F）外，还研究了2-3个月（5M / 5F）的10只CD-1小鼠。在23只小鼠的每只中，将右红外示踪剂（一种近红外染料，与牛血清白蛋白偶联的QC-1）注入右眼，并用11种不同波长的激光脉冲对同侧颈淋巴结进行成像注射后20分钟，2分钟，4小时和6小时。在每个成像会话中计算节点的平均像素强度（MPI）。计算两组小鼠的曲线下面积（AUC），并使用t检验进行比较。在调整右眼的性别，体重和眼内压之前和之后，使用线性混合模型比较每个感兴趣区域的MPI斜率。老年组和青年组注射前右眼的平均眼内压相似（分别为12.77±2.01 mmHg和12.90±2.38 mmHg； p = 0.888）。在每只小鼠中，在示踪剂注入右眼后2小时的时间点，在右颈淋巴结中检测到光声信号。在4和6 h成像时间，观察到示踪信号稳定增加。与年幼的小鼠相比，年纪较大的小鼠右颈淋巴结曲线下的面积明显减少（p = 0.007）。调整性别前后，老年小鼠的结节中MPI的斜率均比年轻小鼠显着降低，右眼的体重和眼压（p = 0.003）。总之，老年眼睛的淋巴引流明显减少。这一发现表明，眼中房水，蛋白质和抗原的淋巴清除率降低可能会导致与年龄相关的眼病，例如青光眼和炎性眼病。