Newer lab studies reveal increased posterior chamber depth does not cause ND and that any IOL, irrespective of material or edge design, implanted in the capsule bag can result in ND, which resolves when the very same inciting lens is moved from the bag to the ciliary sulcus.
Dysphotopsia may be one of the most under recognized complications following otherwise unremarkable cataract surgery. Based on subjective symptoms, up to 20% of patents have negative dysphotopsia (ND), a temporal dark shadow after intraocular lens implantation. Other patients have positive dysphotopsia (PD), characterized by light streaks, arcs, central light flashing or star bursts. Some patients may have both ND and PD.
“Overall, dysphotopsia has not been studied particularly well, especially epidemiologically,” said Samuel Masket, MD, founding partner, Advanced Vision Care, and clinical professor of ophthalmology at the David Geffen School of Medicine, Stein Eye Institute, University of California, Los Angeles. “There are likely 400,000 to 500,000 new cases of chronic ND every year globally.”
The good news, he continued, is that early ND symptoms tend to improve over time due to neuro-adaptation, but about 3% of cases will have chronic ND at one year after surgery. The better news is that novel IOL designs and surgical techniques can correct and prevent ND.
PD is directly related to square edge design and the index of refraction of an IOL. The higher the index of refraction, the greater the likelihood of PD after the lens is implanted. The etiology of PD is well understood.
Samuel Masket, MD
This article was adapted from Dr. Masket’s presentation at the 2019 Congress of the European Society of Cataract and Refractive Surgeons. Dr. Masket is the patent holder for an anti-dysphotopic IOL that is being developed by Morcher GmBH