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Invest Ophthalmol Vis Sci. 2020 May 11;61(5):59. doi: 10.1167/iovs.61.5.59.
To physiologically examine the impairment of cortical sensitivity to visual motion during acute elevation of intraocular pressure (IOP).
Motion processing in the cat brain is well characterized, its X and Y cell visual pathways being functionally analogous to parvocellular and magnocellular pathways in primates. Using this model, we performed ocular anterior chamber perfusion to reversibly elevate IOP over a range from 30 to 90 mm Hg while monitoring cortical activity with intrinsic signal optical imaging. Drifting random-dot fields and gratings were used to characterize cortical population responses to motion direction and orientation in early visual areas 17 and 18.
We found that acute IOP elevations at 50 mm Hg and above, which is often observed in acute glaucoma, suppressed cortical motion direction responses. This suppression was more profound in area 17 than in area 18, and more profound in central than peripheral visual field (eccentricities 0°-4° vs. 4°-8°) within area 17. In addition, orientation responses were more suppressed than motion direction responses for the same IOP modulation.
In contrast to human chronic glaucoma that may cause greater dysfunction in large-cell magnocellular than in small-cell parvocellular visual pathways, our direct measurement of cortical processing networks implies that the small X-cell pathway shows greater vulnerability to acute IOP elevation than the large Y-cell pathway in visual motion processing. The results demonstrate that fine discrimination mechanisms for motion in the central visual field are particularly impacted by acute IOP attacks, suggesting a neural basis for immediate visual deficits in the fine motion perception of acute glaucoma patients.
在眼内压（IOP）急性升高期间，从生理学上检查皮质对视觉运动敏感性的损害。
猫脑中的运动处理已得到很好的描述，其 X 和 Y 细胞视觉通路在功能上类似于灵长类动物的小细胞和大细胞通路。使用该模型，我们通过眼前房灌注可逆地升高 IOP，范围从 30 到 90mmHg，同时使用固有信号光学成像监测皮质活动。我们使用漂移随机点场和光栅来描绘早期视觉区域 17 和 18 中皮质群体对运动方向和方向的反应。
我们发现，急性青光眼常观察到的 50mmHg 及以上的急性 IOP 升高会抑制皮质运动方向反应。这种抑制在 17 区比 18 区更为明显，在 17 区的中央视野（偏心度 0°-4°比 4°-8°）比周围视野更为明显。此外，对于相同的 IOP 调制，方位响应比运动方向响应受到更大的抑制。
与可能导致大细胞大细胞比小细胞小细胞视觉通路更大功能障碍的慢性青光眼不同，我们对皮质处理网络的直接测量表明，在视觉运动处理中小 X 细胞通路对急性 IOP 升高比大 Y 细胞通路更为敏感。结果表明，中央视野中运动的精细分辨机制特别容易受到急性 IOP 攻击的影响，这为急性青光眼患者精细运动感知中即时视觉缺陷提供了神经基础。
