cataract is removed may be less likely to need additional glasses compared with people who have standard monofocal lenses. However, people receiving multifocal lenses may experience more visual problems than with monofocal lenses. The most common adverse visual effects from multifocal IOLs include glare, halos (rings around lights), and a loss of contrast sensitivity in low-light conditions. Adjustable Lens An adjustable IOL is unlike any other lens as its prescription power can be adjusted after surgery once all healing is complete. All other IOLs require surgeons to use pre-surgery measurements to determine a patient's post-surgery lens power. The drawback of this is that pre-surgery measurements are taken while a patient still has cataracts, and they can't account for minuscule shifts that occur during healing. An adjustable IOL allows surgeons to implant it and then, once healing is complete, use an Ultra Violet light delivery device to fine tune it until it suits the patient. An early example being the (RxSight) Light Adjustable Lens (LAL). The eyes and lenses must not be exposed to random ultraviolet light before and during the adjustment process, and protective glasses must be worn from the operation until the lens is locked. When the eye has healed, which is usually 2 to 4 weeks after IOL implantation, refraction adjustment is done. A prescription is formulated for the patient and customization of the IOL's refractive power is done by exposing either the centre or the periphery of the lens to a metered dose of UV light, with the help of a contact lens on the cornea. This exposed part will swell slightly, adjusting the lens surface curvature. Meridional exposure can be done in much the same way to correct for astigmatism. Several exposures can be made for fine tuning, spaced over several days. Once the lens has been optimised a final exposure of the whole lens is made to lock the changes, after which the lens will no longer be adjustable and can be used outdoors. Accommodating Some newer lens designs attempt to allow the eye to regain some partial focusing ability in order to change focus from distance to near (accommodation). However, many accommodating IOLs used today only achieve a very limited improvements in near vision which reduced over time. Accommodative intraocular lenses may also have a slightly higher risk of developing posterior capsule opacification (PCO), though there is some uncertainty around this finding. PCO is