Which factor is NOT associated with the sudden painless loss of vision?

Acute glaucoma typically presents with sudden onset pain, along with vision changes, making it a distinct condition from those associated with a sudden painless loss of vision. The other factors mentioned—diabetes, retinal detachment, and occlusion of the central retinal artery—can indeed lead to sudden vision loss without pain.

Diabetes can cause various eye conditions such as diabetic retinopathy, which can contribute to gradual vision loss or sudden vision changes, but it doesn't inherently cause acute painless vision loss as a primary mechanism. Retinal detachment involves the separation of the retina from its underlying tissue and can cause a sudden painless loss of vision, especially if the macula is involved. Similarly, occlusion of the central retinal artery results in an abrupt and painless loss of vision due to the blockage of blood supply.

In contrast, the hallmark of acute glaucoma includes elevated intraocular pressure that results in significant eye pain, headache, and visual disturbances, making it the outlier among the choices listed.