As all aging ophthalmologists experience first hand, presbyopia is, at a minimum, a nuisance. Beyond the optical correction that is newly required for formerly effortless near-vision activities, presbyopia is a constant reminder that we are aging. Aging is not popular. Our society devotes increasing amounts of attention and resources to delaying the impact of aging. A safe and cost-effective surgical solution for presbyopia is a challenge that ophthalmologists and the ophthalmic technology industry are pursuing eagerly.

The 2 lens-based surgical solutions for presbyopia in current use are the implantation of intraocular lenses (IOLs) with either multifocal optics or optics that are designed to move in the anteroposterior direction, with resultant shift in effective power (so-called accommodating IOLs). Other possible solutions are under investigation. These range from trying to soften the nucleus of the crystalline lens with femtosecond laser pulses to implantation of IOLs with deformable optics.

Multifocal IOLs, by dividing the light energy into 2 different focal planes and simultaneously presenting both foci to the retina, create inevitable side effects, most notably loss of contrast sensitivity and glare and halo at night. Multifocal IOLs have 1 major advantage over accommodating IOLs, however. A multifocal IOL has no moving parts. Motion introduces many variables that affect performance. Ciliary muscle contraction during accommodative effort must translate into an anterior movement of the optic or a deformation of the optic, causing increasing power to shift the focus from distance to near. This requirement means that a change in zonular tension, pressure, or both from the vitreous cavity causes the lens capsule to flex, which then translates into a change in position or shape of the IOL optic. Perhaps future designs of accommodating IOLs will eliminate the necessity for this mechanical coupling (an example is the idea of a hollow IOL filled with 2 immiscible fluids of different index of refractions, resulting in an increase in optical power on downgaze, such as reading [Liquilens; Vision Solution Technology, Rockville, Maryland, USA]). For now, however, flexibility of the capsular bag remains a critical requirement for the function of an accommodating IOL.

In this issue of The Journal, Cleary and associates report their investigation of whether true accommodation can be achieved with an IOL style commonly referred to as bag-in-the-lens. With that IOL, the surgeon creates a primary posterior capsulorrhexis. Both the posterior and anterior capsulorrhexes are inserted into a ridge in the rim of the IOL optic. The hypothesis was that this unique configuration may allow forward motion of the optic during accommodation. If this occurred, the most likely mechanism would be from forward vitreous pressure during accommodation (the catenary mechanism of accommodation postulated by Coleman and Fish).

The authors are to be commended for using the meticulous methodology necessary to separate true accommodation resulting from forward movement of the IOL from pseudoaccommodation resulting from other factors such as pupillary miosis. The bag-in-the-lens IOL did not show any evidence of accommodation. Notably, the manufacturer of this IOL has not made any claims of accommodation. Nevertheless, if the different fixation of this IOL led to maintenance of a flexible capsule, then accommodative movement of the IOL would be plausible.

The search for an accommodating IOL with a reliable range of functional accommodation goes on. Among many aspects of IOL design, maintenance of a flexible capsule after surgery is essential in any IOL that depends on movement of the optic during accommodation.