What is the most likely diagnosis for sudden loss of vision described as seeing a 'bunch of lights'?

The symptoms described, particularly the sudden loss of vision accompanied by the perception of seeing "a bunch of lights," strongly indicate a retinal detachment. This condition often presents with similar visual disturbances, including flashes of light or floating spots as the retina becomes increasingly separated from its underlying support tissue.

Retinal detachment typically occurs rapidly and can lead to significant vision loss if not addressed promptly. The "bunch of lights" the patient experiences is a common symptom due to traction on the retinal surface or the release of debris as the retina pulls away.

In contrast, macular degeneration generally causes gradual vision loss and does not typically present with sudden visual symptoms or flashes of illumination. Cataracts result in clouding of the lens, leading to blurred vision but would not typically cause the perception of lights. Glaucoma usually presents with gradual peripheral vision loss or a halo effect around lights, but would not specifically explain the acute onset and the nature of lights being perceived. Thus, retinal detachment remains the most fitting diagnosis for the symptoms described.