The Add-On IOL (HumanOptics AG, Erlangen,Germany) is a line of sulcus-fixated silicone lensesdesigned for piggyback implantation inpseudophakic patients. When implanted, theseIOLs compensate for residual spherical and astigmaticrefractive errors1,2 or correct presbyopia in patients withmonofocal IOLs.
In our clinical practice, the Add-On is primarilyimplanted in cases of residual astigmatism after penetratingkeratoplasty (PKP). In these cases, we first performcataract surgery and monofocal IOL implantation,then implant the toric Add-On IOL 8 to 12 weeks later.This two-stage approach provides accurate IOL calculation,and it also offers the possibility to explant theAdd-On in the case of repeat PKP. The toric Add-On isalso used in patients with residual astigmatism afterrefractive lens exchange. Implantation of the multifocalAdd-On is fairly rare in our practice and has been performedonly twice.
HumanOptics produces the foldable three-piece siliconeAdd-On IOL for piggyback implantation (Figure1). The posterior surface of the optic is concave toadapt to the already implanted IOL's anterior surface.The overall diameter is 14 mm, and the optic diameteris 6 to 7 mm. The IOL can be implanted with forceps orwith several commercially available injectors.
We have implanted the toric Add-On in 11 eyes (meanage, 70 ±8.8 years; Figures 2 and 3), the multifocal Add-Onin two eyes (mean age, 43.5 ±6.4 years), and the sphericalAdd-On in two eyes (mean age, 61.5 ±9.2 years). In thetoric Add-On group, spherical power ranged from -14.00to -2.00 D (-6.60 ±3.75 D), and toric power from 2.00 to26.00 D (12.40 ±7.10 D). These fairly high astigmatic valuesresulted from previous PKP or cataract surgery. Patient follow-up was conducted at 1 day, 1 month, and 2 months.
At postoperative day 1, for all eyes, mean sphericalequivalent was 0.09 ±0.4, and median distance UCVAwas 0.4 logMAR. The residual astigmatism was -0.38±0.66. At 1 month, spherical equivalent was 0.03 ±0.68,and median distance UCVA was 0.25 logMAR. Theresidual astigmatism was -0.88 ±1.18. At 2 months,spherical equivalent was -0.05 ±0.51, and median distanceUCVA was 0.25 logMAR. The residual astigmatismwas -1.22 ±1.04.
In general, the results achieved with these Add-Onlenses were excellent. IOL implantation was uneventful inall cases and none of the implanted lenses had to beremoved. The IOL calculation was reliable.
There was a good outcome for astigmatic correctionwith the toric Add-On models. Even though not all of thepatients achieved emmetropia, the residual astigmatismwas well within the range that could be corrected withspectacles.
Two patients with very high astigmatism after PKPrequired IOL rotation in the early days after surgery,which was done without complication. Otherwise, nocomplications occurred, including intraocular pressureelevation, pigment dispersion, or fibrin reaction.
In general, the Add-On IOL has been shown to be safeand reliable in compensating for minor to severe refractiveerrors. In very complicated cases, the IOL powersrequired can be calculated by HumanOptics, resulting inexcellent outcomes.3,4
Patients with high astigmatism after PKP can benefitfrom this lens. The possibility to offer multifocality topseudophakic patients is also an attractive solution inrefractive surgery.
Gerd U. Auffarth, MD, is Acting Chairman ofthe Department of Ophthalmology, Universityof Heidelberg, Germany. Professor Auffarthstates that he has no financial interest in theproducts or companies mentioned. He may bereached at e-mail: firstname.lastname@example.org.