A client presenting with a "flash" of light followed by a "curtain" across their vision is likely experiencing which condition?

A client experiencing a "flash" of light followed by a "curtain" across their vision is most indicative of retinal detachment. This condition occurs when the retina separates from the underlying supportive tissue. The initial symptom, the flash of light, may result from the retina being stimulated as it detaches or as vitreous traction pulls on it. Following this, the sensation of a "curtain" over the visual field typically suggests that a portion of the retina has come loose, resulting in the loss of vision in that area.

In contrast, cataracts cause clouding of the lens, leading to blurred vision but not typically to flashes of light or curtain-like vision changes. Glaucoma usually results in the gradual loss of peripheral vision and does not present with these acute symptoms. Macular degeneration primarily affects central vision and does not typically produce the acute onset of flashing lights or a curtain effect. Thus, the symptoms presented align closely with retinal detachment, making it the correct choice.