Piggybacking involves the implantation of two IOLs into one eye in a piggyback fashion.1 This technique is used to treat patients with cataracts and extreme refractive errors (eg, high hyperopia, extremely high myopia and high astigmatism).2
Piggybacking is traditionally performed using three-piece IOLs, however, these lenses have associated disadvantages including lens dislocation into the anterior chamber; pupil capture with resultant acute glaucoma; a visible dimple where the two lenses press against each other, leading to reduced visual quality; and development of red rock syndrome (ie, interlenticular opacity) in cases where the second lens is placed in the capsular bag and the posterior lens has a squared edge.1
STAAR Surgical ICLs (Monrovia, California) offer an alternative to three-piece IOLs for the technique of piggybacking. This lens' design eliminates the possibility of dislocation into the anterior chamber as well as the dimple effect seen with IOLs. Furthermore, the STAAR ICL is easy to implant—the average operation lasts 10 minutes—and calculation of the correct lens size and power is the same as for a standard IOL.3
There are three available STAAR ICLs. The first model corrects myopia, the second hyperopia, and the third model is a toric lens for the correction of myopia with astigmatism. All three lenses are available in four power ranges and four lengths (Table 1). STAAR ICLs may be used (1) after surprises in cataract surgery, (2) to treat ametropia in children who have undergone cataract surgery and lens implantation, (3) when LASIK is contraindicated, (4) when lens power is not available, such as in patients with high hyperopia (use two lenses in this case), and (5) when bioptics cannot be used.
STAAR ICLs were successfully used as an alternative to piggybacking with IOLs for the correction of pseudophakic anisometropia in six adult patients.4 I will present three further cases where STAAR ICLs—rather than traditional three-piece IOLs—have been successfully used for piggybacking.
Case 1. A 7-year-old girl underwent monocular juvenile cataract removal and IOL implantation. Four years later, the child developed myopic anisometropia of 8.00 D. The decision was made to implant a 12.0-mm STAAR ICL with -13.50 D. The lens was implanted into the posterior chamber—on top of the original lens—through a 2.5-mm corneal incision. General anaesthesia was used; peripheral surgical iridectomy was also performed. Prednisolone acetate, 10 mg/mL (Allergan, Irvine, California), and 0.3% ofloxacin (Exocin; Allergan) eye drops, administered four times daily, were used postoperatively.
The patient was examined at 1 day, 1 week, and 6 weeks after surgery. At 6 weeks, anisometropia had been eliminated. The exam revealed that the eye was quiet, the cornea was clear and IOP was normal.
Case 2. A 61-year-old male kidney transplant patient requested LASIK for the treatment of astigmatism and myopia induced by cataract surgery and IOL implantation. The patient had also undergone surgical iridotomy. Ophthalmic examination showed that the left eye was dominant. Refraction in this eye was -1.00/-1.75 x 29, while that in the right eye was -0.5/-0.5 x 150. UCVA was 20/50 in the left eye and 20/30 in the right. Pachymetry showed that the cornea was too thin (n=470 µm) for LASIK. Furthermore, the patient was receiving immunosuppressive therapy (ie, cortisone and cyclosporine), which is a contraindication for PRK.
The patient also showed superior oblique palsy with a head position and was intolerant of the prisms in his prescription spectacles. The patient was not troubled by his head position. Rather, his discomfort was caused by the myopic astigmatism in his left eye. The decision was made to implant a toric STAAR ICL (-4.0/+2.5 x 129 and 12.0 mm in length) into this, his dominant eye. The ametropia in this patient's dominant eye was required to be corrected to make him more comfortable.
Surgical peripheral iridectomy was performed under topical anaesthesia (ie, lignocaine/marcaine 1:1 topical solution). The ICL was implanted through a 2.5-mm clear corneal incision; it was implanted into the sulcus and positioned on top of the previously implanted lens. The use of hydroxypropylmethylcellulose (Ocucoat; Bausch & Lomb, Rochester, New York) maintained the anterior chamber. Postoperatively, one drop of prednisolone acetate 1% (Pred forte; Allergan), and one drop of ofloxacin 0.3% was given every 6 hours. Postoperative examinations were performed at 1 day, 1 week, and 6 weeks.
Six weeks after the operation, refraction was -0.25/-0.75 x 44, UCVA was 20/20 -2 and BCVA was 20/20 +1. The eye was quiet and everything appeared normal. This patient was extremely happy with his vision.
Case 3. A 34-year-old female previously underwent LASIK in the right eye, followed by cataract surgery 6 years later. In 2002, 1 year after cataract surgery, she presented with postphacoemulsification ametropia of 2.50 D. Her refraction was +2.5/-0.5 x 36; UCVA was 20/80 and BCVA was 20/25.
The patient underwent Nd:YAG iridotomy 1 week before lens implantation, and a STAAR ICL of 3.00 D and 12.0 mm was then implanted under topical anaesthesia with oxybuprocaine hydrochloride 0.4% (Minims benoxinate; Bausch & Lomb) through a 2.5-mm corneal incision. The lens was placed into the sulcus behind the pupil and was piggybacked on the previously implanted IOL. Postoperative treatment again included one drop each of prednisolone acetate 1% and ofloxacin 0.3%, four times daily. Ketorolac trometamol 0.5% (Acular; Allergan), was also prescribed three times daily.
Six weeks after piggybacking with the STAAR ICL, refraction was +0.25/-0.5 x 35 and BCVA as well as UCVA was 20/20. The eye was quiet, and no complications were observed. IOP was 13 mm Hg.
These three case studies demonstrate that STAAR ICLs can successfully (1) treat ametropia in children who have undergone cataract surgery and IOL implantation, and (2) correct refractive errors in adults who have undergone cataract surgery and in whom LASIK or PRK is contraindicated (eg, those receiving immunosuppressive therapy or cases where the cornea is too thin). In a previous study,4 STAAR ICLs were implanted in six adult patients with pseudophakic anisometropia ranging from 2.00 D to 7.90 D. All patients showed a reduction in anisometropia to asymptomatic levels, the mean reduction amounting to 3.15 D. As in the cases presented here, no adverse effects were observed.
Use of a STAAR ICL or Toric STAAR ICL for piggybacking offers a unique opportunity to enhance vision in patients who have undergone cataract surgery and in whom LASIK or PRK is contraindicated. The lenses are particularly useful for treating children and offer benefits of quick implantation, reversibility, good visual quality and no dimple effect in the area where the two lenses contact one another.
Johann Kruger, MD, practices at the Tygervalley Eye and Laser Centre, in Cape Town, South Africa and is an honorary consultant to the Ophthalmology Department at the University of Stellenbosch. Dr. Kruger states that he has no financial interest in the products or companies mentioned. He may be reached at drkruger@iafrica.com; phone: +027 21 9100 300; or fax: +027 21 910 0340.
Up Front | Nov 2006
Piggybacking With a STAAR ICL
This technique is a consideration when LASIK or PRK is contraindicated.
Johann Kruger, MD
