After cataract surgery, most patients experience strange optical phenomena called dysphotopsias – essentially unwanted visual artifacts caused by the new lens or how light interacts in the eye.
Positive dysphotopsia refers to seeing added lights or images, like halos, glare, or streaks of light, especially in certain conditions (e.g., rings around lights at night). Some patients will also notice a flickering of light thought to be related to the new lens moving until it settles and heals in the eye. It’s termed “positive” because it’s something extra in your vision (bright artifacts).
Negative dysphotopsia is the opposite – it’s perceived as a dark shadow or missing area in your field of view. Often, negative dysphotopsia manifests as a dark crescent-shaped shadow usually towards the temporal (outer) side. Patients might say “It’s like I have a shadow or I can see the edge of something off to the side.” This can be due to how the edge of the IOL or the structure of the eye and light create a shadow on the retina. The important thing to know is that these dysphotopsias are not signs of something dangerous; they’re related to optics.
Positive dysphotopsias (halos, etc.) are common with multifocal lenses but can happen even with monofocals in some eyes. Negative dysphotopsia is also somewhat common and typically improves over time as the brain adapts. If you experience these, tell your surgeon so they can confirm it’s dysphotopsia and not something else like a retinal tear or detachment. The good news: in most cases, these phenomena lessen or disappear within weeks to months as you neuro-adapt. In rare stubborn negative dysphotopsia, treatments like a repositioning of the lens (i.e. reverse optic capture), additional lens (i.e. secondary piggyback lens), or lens exchange can be considered, but that’s only if it’s truly persistent and bothersome.
Just having a name for these weird shadows or rings can be reassuring – you know it’s a known phenomenon many people experience and it usually gets better naturally. The less you pay attention to these annoying phenomena, the faster your brain will neuroadapt, so try to ignore them!
