What condition can lead to complete blindness if left untreated?

The condition that can lead to complete blindness if left untreated is macular degeneration (MD). Macular degeneration primarily affects the macula, which is the part of the retina responsible for clear and detailed vision. As the disease progresses, central vision deteriorates, severely impacting an individual's ability to read, drive, or recognize faces.

There are two types of macular degeneration: dry and wet. The dry form is more common and generally progresses slowly, while the wet form can lead to rapid vision loss. If either form is not treated, especially the wet form, the damage can become irreversible, resulting in significant loss of vision or even complete blindness.

Other conditions such as glaucoma, cataracts, and retinal detachment can also lead to vision loss if left untreated, but they typically involve different mechanisms or stages of progression. For instance, glaucoma often causes peripheral vision loss and requires ongoing treatment to manage intraocular pressure. Cataracts involve clouding of the lens, which can often be resolved with surgery. Retinal detachment may need surgical intervention to reattach the retina before permanent vision loss occurs. Thus, while these conditions are serious, macular degeneration stands out for its direct link to loss of central vision and potential for complete blindness when not managed properly