These lenses are implanted in front of the crystalline lens. This type of lenses is more often used when laser surgery is contraindicated such as with very high myopia or thin cornea. They have essentially the same effect as contact lenses. This means that visual acuity is expected to be better than with spectacles in the case of myopes.
The ocular complications created by the extra bulk of an additional lens in the posterior chamber (behind the iris and in front of the crystalline lens) need to be monitored. As the natural lens continues to grow throughout life, the positioning and the safety of the ICL may be compromised. If the ICL is in contact with the natural lens there is a risk of cataract. In this case the ICL may need to be removed together with the natural lens and replaced by a traditional IOL. ICLs can also displace and no longer be centred on the visual axis.
The risk of retinal detachments is significantly increased with high myopia. This is not reduced by the implantation of corrective lenses. Binocularity should not be affected.
Providing the ICL does not become coated with any inflammatory materials as a result of uveitis etc, the clarity of the ICL should be maintained as should contrast sensitivity and glare sensitivity.
Collamer lenses are generally not acceptable because of their possible complications and the reasons for using them.