Scleral tunnel intraocular lens explantation: comment

Abstract

Scleral tunnel intraocular lens explantation: comment I read with interest the case series by van Zyl et al. where intraocular lense (IOL) explantation was achieved via sutureless long scleral tunnels fashioned as in manual small incision cataract surgery (MSICS). 1 I recently travelled overseas to learn MSICS. Upon my return to Australia, two cases of subluxated IOLs presented and I utilised scleral tunnelling for IOL explantation.Patient 1 had a sudden IOL dislocation 25 years after original cataract surgery. A three-piece IOL was found in the anterior vitreous and the capsular bag was not identifiable. A scleral tunnel was fashioned superiorly, and an anterior chamber (AC) entry was initially limited to one pass of the keratome to facilitate anterior vitrectomy and anteriorisation of the IOL while maintaining AC stability. After applying acetylcholine, the scleral tunnel was widened to facilitate IOL removal and permit implantation of an AC IOL. However, surgical peripheral iridectomy (PI) was difficult due to the length of the scleral tunnel and caused significant iris trauma. The resulting vitreous haemorrhage caused delayed visual rehabilitation. Upon clearance of the vitreous haemorrhage 3 months later, the patient saw 6/7.5 with À0.25 D DS. Surgically induced corneal astigmatism was 1.31 D.Patient 2 had cataract surgery more than 20 years ago complicated by PC rupture and retinal detachment necessitating pars plana vitrectomy. He received a sclera-fixated poly(methyl methacrylate) one-piece IOL 13 years ago, but one of the sutures broke causing subluxation. A neodymium-doped yttrium aluminium garnet laser PI was performed preoperatively. A scleral tunnel was fashioned, and anteriorisation of the IOL was successful after removing the other remaining suture. After removal of the IOL from the scleral tunnel, an AC IOL was implanted without surgical PI. Visual rehabilitation was rapid, and after 6 weeks, the patient achieved 6/9 with +0.5 D DS. Surgically induced astigmatism was 1.30 D.I agree with van Zyl et al. that IOL explantation via deep scleral tunnels provides several advantages over clear corneal incisions. Cutting or folding IOLs in the AC inherently possesses significant risk of injury to the endothelium, capsular bag and iris. Large rigid IOLs that cannot be cleaved intracamerally, such as in Patient 2 aforementioned, would require very large corneal incisions to remove, which means unstable ACs for long periods of time while suturing is being completed. The risks of vitreous loss, retinal detachment, suprachoroidal haemorrhage and endophthalmitis are increased while suturing with an unstable AC, and the amount of induced corneal astigmatism from such large wound would be considerable. The scleral tunnel allows removal of large IOLs without the need to cleave or fold them intracamerally, a more stable AC throughout the surgery and decreased operating time and corneal astigmatism because suturing is unnecessary.I found two practical points helpful. Firstly, after fashioning a scleral tunnel wide ...