Nulens iol accommodating
Understanding the mechanism of lens shape change in accommodation has become essential to the general ophthalmologist as the array of intraocular lenses (IOLs) designed to restore ciliary body/lens capsular-generated accommodation, under FDA scrutiny, grows.
The designers of these lenses all assume that the aphakic ciliary body will continue to function interchangeably from one eye to the next with predictability over time — an assumption that remains unproven.
First, two capsular-based flex mechanism IOLs claiming to restore accommodation are FDA approved: Crystalens and its toric cousin Trulign (Bausch & Lomb) and Tetraflex (Lenstec).
Both function by the mechanism of ciliary body-zonular generated lens flexion. Developing novel endpoints for premium intraocular lenses workshop.
The Crystalens and Trulign are designed to both stabilize the lens in the capsular bag and to allow the lens optic to vault forward with ciliary body contraction in the presence of an increase in vitreous pressure.
The knock against flex mechanism lenses has been their extreme variability in degree and duration of accommodative effect.
Additionally, there are no agreed-to standards of true accommodation.
This pushes the silicone fluid between the two optics and creates an accommodative effect of the lens. He hypothesized that the aging presbyopic lens grows equatorially, inducing a slackening of the lens zonules and rendering ciliary body contraction ineffective. This is based upon scleral expansion procedures designed to correct presbyopia. The latter has been the subject of considerable debate. In 1855, Hermann von Helmholtz suggested that a constriction of the ciliary body musculature leads to slackening of its attached lens zonular fibers, producing a consequential increase in lens curvature.