PAC eye refers to Primary Angle Closure (PAC), a stage in the progression of angle-closure glaucoma where the eye's drainage angle is narrowed or blocked, leading to elevated intraocular pressure (IOP). This elevated pressure can damage the optic nerve. This narrowing or blockage is caused by the iris (the colored part of the eye) pressing against the trabecular meshwork, which is responsible for draining fluid from the eye.
Here's a breakdown:
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Angle Closure: The angle formed where the iris meets the cornea is critical for draining fluid (aqueous humor) from the eye. When this angle narrows or closes, fluid cannot drain properly.
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Primary: This indicates that the angle closure isn't caused by other conditions, such as trauma or neovascularization. The underlying anatomical predisposition of a narrow angle is the primary cause.
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Elevated IOP: In PAC, the narrowed or closed angle results in increased intraocular pressure (IOP), which can damage the optic nerve. Notably, elevated IOP needs to be present either currently or at some point in the past to classify as PAC.
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Peripheral Anterior Synechiae (PAS): These are scar tissue formations that develop as the iris adheres to the trabecular meshwork, further obstructing the outflow of aqueous humor. The presence of PAS is also indicative of PAC.
In summary, PAC is characterized by angle closure, elevated IOP (past or present), and/or the presence of peripheral anterior synechiae. It's a significant stage in the angle-closure glaucoma spectrum and requires careful monitoring and management to prevent vision loss.
