However, it is unclear if these documented changes in the ciliary muscle and the lens sclerosis occur together or if one is a consequence of the other. Thus, the ideal AIOL would fully resolve the inconvenience of presbyopia and the side effects in relation with current surgical options as the positive visual symptoms or the deterioration of quality of vision after multifocal IOL implantation.Obviously, this ideal AIOL would have a huge impact in refractive surgery and private practice, which explains the interest from the different companies in developing such lenses.In this article, we will update the modern refractive surgeon about the fundamentals and provide updated information about the outcomes of AIOLs by reviewing the concept of accommodation, the different attempts that have been accomplished in the past, their demonstrated published results in human clinical trials, and the future alternatives that may arrive in the near future.Presbyopia is the physiological degradation of accommodation and still remains as the last frontier of refractive surgery as its surgical management is perhaps the most innovative and challenging and is under constant renewal.Approximately, 1 mm of movement is equivalent to almost a 2 D power change.These lenses are known as “positional pseudoaccommodative IOLs”, and their visual results in terms of providing partial or total near visual acuity restoration in the long term have been disappointing.
The aging population, especially in western countries, has created millions of candidates around the world for such interventions.
The elasticity of the capsule is held in check by the normal tension in the zonule so that accommodation consists in the relaxation of the tension in the zonule by the contraction of the ciliary muscle.
This permits the capsule to mold the lens into a more strongly curved system (Table ], the loss of accommodative power (presbyopia) is essentially due to the progressive failure of the capsule to mold the lens into a more spherical shape when the zonule is relaxed as a consequence of the progressive sclerosis and hardening of the lens substance with age.
This concept refers to any other method that changes the power of the whole optical system of the eye or changes partly the way in which it works in order to relieve patients for near distance vision.
Nevertheless, pseudoaccommodation is not a real restoration of accommodation [The theory of accommodation is largely based on Helmholz's ideas: the capsule has sufficient elasticity to mold the lens into a more strongly curved system than what is necessary for distance vision.
Theoretically, when plate lenses are placed into the capsular bag, the anterior capsule fibroses and applies end-to-end pressure on the plates, which vaults posteriorly and the optic comes to lie up against the vitreous face.