Hypotony is often defined as intraocular pressure (IOP) less than 6 mm Hg. It has been reported to occur after glaucoma filtering surgery in up to 42% of cases and is usually associated with overfiltration or wound leaks. Hypotony requiring revision, however, occurs in about 4% of filtering procedures. Hypotony can follow any IOP-lowering procedure or even “simple” cataract surgery. The advent of guarded filtering surgery has reduced the rate of hypotony significantly compared to full-thickness filtering surgery. Unfortunately in the quest to increase success rates by using adjunctive antifibrotic agents, such as mitomycin-C (MMC) or 5-fluorouracil (5-FU), that prevent fibrotic wound healing, the incidence has increased again. Higher doses of and longer exposure times to MMC are associated with a greater risk of hypotony. Most cases of hypotony are transient and self-limited to a few days or weeks after surgery. Transient hypotony does not seem to have any deleterious effect on long-term visual acuity. However, persistent hypotony may result in structural changes that can become permanent. Hypotony maculopathy is one such condition manifesting from persistent hypotony that can result in permanent vision loss. Hypotony maculopathy occurs in up to 10% of filtering operations with MMC or 5-FU and in about 10% of eyes with chronic hypotony. Maculopathy associated with hypotony was first described by Dellaporta. Some years later, Gass, using fluorescein angiography, better characterized the condition. In hypotony maculopathy, the sclera and choroid develop folds in the posterior pole, which can cause significant visual disturbances. The condition is recognized by characteristic striae or folds in the macular area that do not leak or stain with fluorescein. The posterior sclera appears partially collapsed, causing the folds. The axial length of the eye may be shortened after both filtering and tube shunt surgery and more so in patients with hypotony. The loss of vision is usually gradual after the hypotony has persisted for at least a month or more. Indocyanine green angiography has revealed some vascular abnormalities including vessel tortuosity and filling defects.