这种病发生在眼部排水渠道完全堵塞时，而且症状明显——视力模糊、头痛、眼痛并作呕。

This happens when the drainage canals become completely blocked, and symptoms can be vivid - blurred vision, headaches, eye pain and nausea.

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最常见的是开角型青光眼（open-angle glaucoma）。 患这种病的眼部排水渠道被部分堵塞。

The most common is primary open-angle glaucoma, in which the eye’s drainage canals are partly clogged.

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城市其他老城区的排水渠道和排水设备有有了进一步的提高，这些设施直到被2005年卡崔娜飓风淹没之前，一直运转良好。

Further improvements in drainage canals and pumping equipment in the older sections of the city were also made. These operated well until they were overwhelmed by Hurricane Katrina in 2005.

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