In the case of a patient with high hyperopia, biometry may suggest an IOL power beyond what is commercially available. The upper limit of commercially available IOL power is now +40.00 D. A special-order IOL of a higher power may be available or may be designed, but acquiring or designing such a lens usually requires the approval of the institutional review board at the hospital or surgical center, which delays the surgery. Another option is to use a “piggyback” IOL system, in which 2 posterior chamber IOLs are inserted. One IOL is placed in the capsular bag, and the other is placed in the ciliary sulcus. When piggyback IOLs are used, the combined power may need to be increased +1.50 to +2.00 D to compensate for the posterior shift of the posterior IOL. One serious complication of piggyback IOLs is the potential for developing an interlenticular opaque membrane. These membranes cannot be mechanically removed or cleared with the Nd:YAG laser; the IOLs must be removed. Interlenticular membranes have occurred most commonly between 2 acrylic IOLs, especially when both IOLs are placed in the capsular bag. When piggyback lenses are used, they should be of different materials and the fixation should be split between the bag and the sulcus. Piggyback IOLs may also shallow the anterior chamber and increase the risk of iris chafing, especially in smaller eyes.

Hill WE, Byrne SF. Complex axial length measurements and unusual IOL power calculations. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2004, module 9.

Shammas HJ. IOL power calculation in patients with prior corneal refractive surgery. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2013, module 6.

Complications

At more than 2 years postoperatively, the incidence of retinal detachment in 1519 consecutive patients (2356 eyes) with an axial length greater than 27.0 mm was reported to be 1.5%–2.2%, a level that corresponds to the incidence of idiopathic retinal detachment in myopia.

Horgan N, Condon PI, Beatty S. Refractive lens exchange in high myopia: long term follow up. Br J Ophthalmol. 2005;89(6):670–672.

Neuhann IM, Neuhann TF, Heimann H, Schmickler S, Gerl RH, Foerster MH. Retinal detachment after phacoemulsification in high myopia: analysis of 2356 cases. J Cataract Refract Surg. 2008;34(10):1644–1657.

Advantages

Refractive lens exchange has the advantage of greatly expanding the range of refractive surgery beyond what can be achieved with other available methods. The procedure retains the normal contour of the cornea, which may enhance the quality of vision, and it may be used to treat presbyopia as well as refractive error with incorporation of multifocal and/or accommodating IOLs.

Disadvantages

Quality of vision may not be as good with current multifocal IOLs as with other forms of vision correction. Patient expectations for excellent uncorrected visual acuity may be higher for RLE than for cataract surgery, underscoring the need for thorough preoperative discussion, close attention to detail preoperatively and intraoperatively, and postoperative treatment of residual refractive error.

Monofocal Intraocular Lenses

For some patients, the best IOL choice for implantation at the time of RLE is a monofocal IOL. There are a variety of IOL choices and styles available, and all are utilized in routine cataract surgery as well (see BCSC Section 11, Lens and Cataract, for more detail). Patients without significant corneal