After the cataract surgery or intraocular lens implantation, some patients may report that ‘they can see dark shadow at the edge of the vision’ or ‘part of the vision is missing’.
Many of these cases are called negative dysphotopsia.
This phenomenon refers to postoperative symptoms in which patients can see a dark area or a sense of obstruction in part of their vision. It is commonly described as a crescent-shaped shadow on ear side or as if there is ‘curtain’ present in part of the vision.

The exact cause is still under discussion, one widely accepted explanation is, a portion of light reaches to the retina directly through the gap between the iris and the intraocular lens, while the other portion passes through and refracts via the intraocular lens. The discrepancy between those two light paths creates a gap, resulting in the darker vision.

Because the dark region may become larger when the pupil is small, miotic agents do not improve this symptoms.

Visual acuity tests are usually normal, and most patients gradually become less bothered by the symptoms over time.
Usually, negative dysphotopsia is improved naturally, but if the symptom persists please consult with the ophthalmologists.