All other IOLs require surgeons to use pre-surgery measurements to determine a patients post-surgery lens power. The drawback of this is that pre-surgery measurements are taken while a patient still has cataracts, and they cant 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). 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 a common side-effect of many cataract surgeries and is easily treatable with a one-time laser capsulotomy procedure (see below). Accommodating IOLs interact with ciliary muscles and zonules, using hinges at both ends to "latch on" and move forward and backward inside the eye using the same mechanism as normal accommodation. These IOLs have a 4.5-mm square-edged optic and a long hinged plate design with polyimide loops at the end of the haptics. The hinges are made of an advanced silicone called BioSil that was thoroughly tested to make sure it was capable of unlimited flexing in the eye.
During CLEAR, the crystalline lens is extracted and an IOL replaces it in a process that is very similar to cataract surgery: both involve lens replacement, local anesthesia, last approximately 30 minutes, and require making a small incision in the eye for lens insertion. People recover from CLEAR surgery 1–7 days after the operation. During this time, they should avoid strenuous exercise or anything else that significantly raises blood pressure. They should visit their ophthalmologists regularly for several weeks to monitor the IOL implants. CLEAR has a 90% success rate (risks include wound leakage, infection, inflammation, and astigmatism). CLEAR can be performed only on patients ages 40 and older. This is to ensure that eye growth, which disrupts IOL lenses, will not occur post-surgery. Once implanted, IOL lenses have three major benefits. First, they are an alternative to the excimer laser procedure (LASIK), a form of eye surgery that does not work for people with serious vision problems. Effective IOL implants also eliminate the need for glasses or contact lenses post-surgery for most patients. The cataract will not return, as the lens has been removed. The disadvantage is that the eyes ability to change focus (accommodate) has generally been reduced or eliminated, depending on the kind of lens implanted.