The aim of this study is to investigate the characteristics of the aqueous humour flow in the anterior chamber of the eye in the presence of a perforated, phakic, iris-fixated intraocular lens (pIOL). Such pIOLs are implanted in the anterior chamber in front of the iris and therefore they interfere with aqueous motion. The aim of this work is to investigate whether a perforation in the body of the pIOL can improve its fluid dynamics performance. Numerical simulations are conducted using the free computational fluid dynamics program OpenFOAM. The aqueous humour is modelled as a Newtonian incompressible fluid and, when temperature effects are considered, the Navier–Stokes equations are coupled to the energy equation, using Boussinesq’s approach to account for fluid density changes associated tem- perature variations. The pressure drop across the anterior chamber is calculated considering perfora- tions in the pIOL of various sizes and also studying the extreme case in which the passage between the iris and the pIOL gets plugged, thus leaving the hole in the pIOL as the only possible pathway for aqueous flow. The study shows that the presence of a hole in the pIOL can only have a significant role on the pressure in the eye if the normal aqueous flow in the region between the pIOL and the iris gets blocked and has a negligible effect on the wall shear stress on the cornea

Iris-fixated aphakic intraocular lenses (IFIOL) are used in cataract surgery, when more common intraocular lenses cannot be adopted because of the absence of capsular bag support. These lenses can be implanted either on the poste- rior or the anterior surface of the iris. In this work we study whether one of these options is preferable over the other from the mechanical point of view. In particular, we focus on the forces that the IFIOL transmits to the iris, which are asso- ciated with the risk of lens dislocation. We study the prob- lem numerically and consider aqueous flow induced by sac- cadic rotations in the cases of an IFIOL in the anterior and posterior side of the iris. The IFIOL considered is the Arti- san Aphakia +30.0 D lens (IFIOL) produced by Ophtec BV. We perform the simulations in OpenFOAM. We find that the forces transmitted by the aphakic IFIOL to the iris are sig- nificantly higher in the case of posterior implantation. This suggests that lens implantation on the posterior surface of the iris might be associated with a higher risk of lens disloca- tion, when an inadequate amount of iris tissue is enclavated during implantation.

PURPOSE. Corneal endothelial cell loss is one of the possible complications associated with phakic iris-fixated intraocular lens (PIOL) implantation. We postulate that this might be connected to the alteration of corneal metabolism secondary to the lens implantation. METHODS. A mathematical model of transport and consumption/production of metabolic species in the cornea is proposed, coupled with a model of aqueous flow and transport of metabolic species in the anterior chamber. RESULTS. Results are presented both for open and closed eyelids. We showed that, in the presence of a PIOL, glucose availability at the corneal endothelium decreases significantly during sleeping. CONCLUSIONS. Implantation of a PIOL significantly affects nutrient transport processes to the corneal endothelium especially during sleep. It must still be verified whether this finding has a clinical relevance.

One of the possible risks associated with the implant of iris-fixated phakic intraocular lenses (pIOL) is loss of corneal endothelial cells. We hypothesize that this might be due to alterations in corneal metabolism secondary to the lens implantation. To verify the feasibility of this assumption, we propose a mathematical model of the transport and diffusion of metabolic species in the anterior chamber and the cornea, coupled to a model of aqueous flow. Results are obtained both with and without the pIOL in the case of closed eyelids. The results suggest that glucose availability may be significantly reduced at the corneal endothelium. However, it must still be verified whether this finding has clinical relevance.