2.11\ Intraocular Lens Implants

2.11.1\ Discussion

Cataract is a common cause of reversible vision loss and can be treated via cataract extraction and intraocular lens implantation when symptomatic. Intraocular lens implants consist of two main components: the optic and two haptics. These lens implants can be composed of polymethylmethacrylate, silicone, hydrogel, polyethylene, polypropylene, or a combination of these. The lens implants may be positioned posterior or anterior with respect to the plane of the iris. Unlike native lenses, lens prostheses are very thin structures in profile, as seen on an axial image. The optic appears as hyperattenuating on CT and is of low signal intensity on both T1and T2-weighted MRI sequences (Fig. 2.43). The haptics are not readily visible at 1.5 T or on thin-­section CT. Intraocular lens implants do not normally enhance. Complications of cataract surgery with intraocular lens implants include retained lens fragments, implant dislocation, and less commonly dystrophic calcifications. Implant dislocation can result from inadequate capsular or zonular support or following traumatic injury. While some of these complications may be apparent on CT and MRI (Figs. 2.44 and 2.45), ophthalmic ultrasound is generally the modality of choice, but is beyond the scope of this text.

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Fig. 2.44  Intraocular lens implant dislocation. Axial T2 MRI shows the posteriorly displaced left lens implant (arrow)

Fig. 2.45  Intraocular lens implant dystrophic calcification. Axial CT image shows irregular clumps of calcification deposited on the surface of the left lens implant (arrow)