IOL DESIGN CHALLENGES REMAIN IN ADDRESSING DYSPHOTOPSIAS

Dysphotopsias remain an issue to be solved by next-generation intraocular lenses (IOLs) or by more rigorous IOL selection based on dysphotopsia diagnostics, Patricia Piers PhD, the Netherlands, told a Clinical Research Symposium at the XXXIII Congress of the ESCRS yesterday.

“There is still a lot of discussion on the causes of and solution for negative dysphotopsia. The causes may be multifactorial and trade-offs are involved with almost all potential solutions,” she said.

Defining dysphotopsia as subjectively reported, bothersome light-related phenomena associated with uncomplicated cataract or IOL surgery, Dr Piers said it can be further subdivided into three main categories: positive dysphotopsia (bright arcs, streaks or flashes, starbursts); negative dysphotopsia (dark arcs or shadows); and multifocal positive dysphotopsia (halos, glare, starbursts, rings, night vision problems).

Reported rates of positive and negative dysphotopsia vary from 10 to 20 per cent on day one postoperatively, reducing to two to three per cent at follow-up points ranging from one month to one year. The reported exchange or explantation rate is about 0.13 per cent, she said.

For multifocal dysphotopsia, there are spontaneous reports of severe halos, glare, starbursts and night vision problems in one per cent to nine per cent of cases at six months postoperatively, with the rate dependent on IOL design.

Looking at the measures taken by IOL manufacturers to address these problems, Dr Piers cited innovations such as the introduction of round anterior edge designs, reduced edge thickness, frosted edge, altered power ratios and lower refractive index materials.

Such modifications invariably involve some trade-offs – such as anterior or posterior capsule opacification, IOL stability or larger incisions – that need to be assessed carefully in the overall performance of the lens, said Dr Piers.