Department of Mathematics and Statistics, Metropolitan State University of Denver, P.O. Box 173362, Campus Box 38, Denver, CO 80217, USA.
Department of Mathematical Sciences, Indiana University Indianapolis, 402 N. Blackford St, LD 270, Indianapolis, IN 46202, USA.
Math Biosci. 2024 Nov;377:109292. doi: 10.1016/j.mbs.2024.109292. Epub 2024 Sep 5.
Vascular impairments, including compromised flow regulation, have been identified as significant contributors to glaucomatous disease. Recent studies have shown glaucoma patients with significantly reduced peripapillary, macular, and optic nerve head vessel densities occurring with early glaucomatous structural changes prior to detectable visual field loss. This study aims to quantify the potential impact of decreased vessel densities on retinal perfusion and oxygen metabolism. In our clinical observations, pre-perimetric glaucoma patients exhibited a 10-13 % reduction in vessel density compared to healthy individuals. Our theoretical model of the retinal vasculature is adapted in this study to assess the potential impact of this reduction in vessel density on retinal oxygenation. The model predicts a 1 % and 38 % decrease in mean oxygen saturation in retinal vessels immediately downstream of the capillaries when vessel density is decreased from its reference value by 10 % and 50 %, respectively. The impact of capillary loss on oxygen extraction fraction and the partial pressure of oxygen in retinal tissue is also predicted. Reductions in vessel density are simulated in combination with impaired flow regulation, and the resulting effects on saturation and flow are predicted. The model results showed a nonlinear relationship between vessel density and downstream saturation, indicating that larger decreases in the density of capillaries have a disproportionate impact on oxygenation. The model further demonstrates that the detrimental effects of minor vessel density reductions are exacerbated when combined with other vascular impairments.
血管损伤，包括血流调节受损，已被确定为青光眼疾病的重要致病因素。最近的研究表明，青光眼患者在出现可检测的视野损失之前，就已经出现了视乳头周围、黄斑和视神经头部血管密度显著降低的情况，这些变化伴随着早期的青光眼结构改变。本研究旨在量化血管密度降低对视网膜灌注和氧代谢的潜在影响。在我们的临床观察中，在出现视野缺损之前，青光眼患者的血管密度比健康个体降低了 10-13%。本研究中，我们对视网膜血管的理论模型进行了调整，以评估血管密度降低对视网膜氧合的潜在影响。该模型预测，当血管密度分别降低到参考值的 10%和 50%时，视网膜血管中毛细血管下游的平均氧饱和度将分别降低 1%和 38%。该模型还预测了毛细血管丧失对视网膜组织中氧提取分数和氧分压的影响。结合血流调节受损，模拟了血管密度的降低，并预测了对饱和度和流量的影响。模型结果表明，血管密度与下游饱和度之间呈非线性关系，这表明毛细血管密度的较大降低对氧合的影响不成比例。该模型进一步表明，当与其他血管损伤结合时，较小的血管密度降低的有害影响会加剧。
