Piggyback Implantable Collamer Lens Implantation To Correct Residual Mixed Astigmatism After Cataract Surgery:A Case Report

This article reports a case of successful correction of mixed astigmatism using piggyback implantable collamer lens.

In recent years, the accuracy of preoperative cataract biometry and phacoemulsification has been improved, However, residual refractive error after cataract surgery still exists due to some errors in the process of surgical operation and biometry. There are many methods to correct residual refractive errors, such as wearing glasses or corneal contact lens, corneal refractive surgery, IOL exchange or piggyback implantable collamer lens (ICL). 

A 56-year-old man who underwent binocular monofocal intraocular lens implantation after phacoemulsification 1 year ago complained of blurred vision in his left eye with dry eyes. Slit-lamp examination showed the temporal corneal scar of the left eye, the right eye is deviated outward and upward, and the left eye is orthotopic. The uncorrected distance visual acuity(UDVA) in both eyes was 20/800, corrected distance visual acuity (CDVA) in the right eye was 20/100 and 20/20 in the left eye. The dominant eye is the left eye. ICL power and size calculations were performed by the manufacturer (STAAR Surgical) using a modified vertex formula based on the patient's information. The piggyback ICL power was +2.50/+5.5/×155, with the size being 12.6 mm. Considering the sulcus-to-sulcus (STS) length measured by ultrasound biomicroscopy (UBM) in patient, then the power was +2.50/+5.5/×155 and the size was 12.1 mm.

The piggyback ICL was implanted in the patient's left eye. The UDVA of the left eye was 20/20 one week after surgery and 20/25 two months after surgery, and the endothelial cell density (ECD) did not change significantly compared with before operation. There is no intraoperative and postoperative complications.

Considering the patient's age-related dry eye and anisometropia, wearing glasses would increase asthenopia and wearing contact lenses would carry the risk of infection. Dry eye, flap complications, haze or corneal scarring may be the complications after corneal refractive surgeries. IOL exchange maybe lead capsule tear and zonule injury. ICL implantation avoids the above disadvantages while reducing the risk of increased surgically induced astigmatism and higher-order aberrations. Smaller surgical incisions cause less loss of corneal endothelium cells.