Distinguish open-angle glaucoma from angle-closure glaucoma in mechanism.

Distinguish open-angle glaucoma from angle-closure glaucoma in mechanism.

• A. Open-angle glaucoma is caused by pupillary block; angle-closure by gradual outflow obstruction.
• B. Open-angle and angle-closure glaucoma have the same mechanism.
• C. Open-angle: angle narrowing or pupillary block causing sudden IOP rise.
• D. Open-angle: gradual obstruction of trabecular outflow leading to elevated IOP; angle-closure: angle narrowing or pupillary block causing sudden IOP rise.

Answer: (D)

The main distinction is where the blockage to aqueous humor outflow occurs and how the eye structure contributes to the pressure rise. In open-angle glaucoma, the drainage angle is open, but there is gradual resistance to outflow through the trabecular meshwork. This leads to a slow, progressive increase in intraocular pressure and chronic optic nerve damage over time. In angle-closure glaucoma, the angle between the iris and cornea narrows or closes, often due to pupillary block or iris-lens crowding. This mechanical blockage stops aqueous from reaching the trabecular outflow pathway, causing a rapid, sometimes sudden rise in intraocular pressure and acute symptoms. So the correct description aligns with open-angle glaucoma as gradual obstruction of trabecular outflow, and angle-closure as angle narrowing or pupillary block causing a sudden IOP rise. The other descriptions mix up the mechanisms or imply the same mechanism for both types, which doesn’t fit how these conditions actually occur.

The main distinction is where the blockage to aqueous humor outflow occurs and how the eye structure contributes to the pressure rise. In open-angle glaucoma, the drainage angle is open, but there is gradual resistance to outflow through the trabecular meshwork. This leads to a slow, progressive increase in intraocular pressure and chronic optic nerve damage over time.

In angle-closure glaucoma, the angle between the iris and cornea narrows or closes, often due to pupillary block or iris-lens crowding. This mechanical blockage stops aqueous from reaching the trabecular outflow pathway, causing a rapid, sometimes sudden rise in intraocular pressure and acute symptoms.

So the correct description aligns with open-angle glaucoma as gradual obstruction of trabecular outflow, and angle-closure as angle narrowing or pupillary block causing a sudden IOP rise. The other descriptions mix up the mechanisms or imply the same mechanism for both types, which doesn’t fit how these conditions actually occur.