Indications for explant of implantable collamer lens

Sir,

Implantable collamer lens (ICL) (Visian, STAAR Surgical Co., CA, USA) is a posterior chamber phakic intraocular lens (pIOL) that was FDA approved in 2005 for the correction of moderate-to-high myopia.¹ ICL explant may rarely be needed in the event of complications related to inappropriate vaulting and its consequences. ^{2, 3, 4}

We herein evaluated the indications for ICL explant over the last 3 years in our institution. Ethical clearance was obtained from the institutional review board. Eleven cases underwent ICL explant, and the demographic details of the cases, indications for explant, and visual and anatomical outcomes have been summarised in Table 1. Reasons for ICL explant were chipped haptic of ICL during insertion (1 out of 11), first-stage ICL explant with phacoemulsification before vitreoretinal surgery (2 out of 11), silicon-oil-induced cataract (1 out of 11), inverse ICL with cataract & retinal detachment (1 out of 11), post-traumatic ICL dislocation with anterior subcapsular cataract (1 out of 11), nuclear sclerosis (1out of 11), anterior subcapsular cataract with shallow vault (1 out of 11), high vault with raised intraocular pressure (1 out of 11), shallow vault with recurrent uveitis (1 out of 11), and acute post-operative endophthalmitis (1 out of 11).

Table 1 Demographic details, indications for explant and outcomes in cases undergoing ICL explant

Zeng et al observed an incidence of 2.6% (16 out of 616) for pIOL exchange, with low vaulting (≤100 μm) leading to cataract in 50% cases, and too high vaulting (≥1000 μm), leading to raised IOP in 50% cases.² In contrast, we performed ICL exchange in only two cases because of inadequate vault. Shallow vault resulted in anterior subcapsular cataract in one case, and excessively high vault led to raised IOP in another case.

The reported incidence of post-ICL cataract is 5.2%.³ In our series, a concomitant phacoemulsification with IOL implantation was performed in 63.6% (7 out of 11) cases. Of these, 57.1% cases (4 out of 7) required phacoemulsification to facilitate subsequent retinal surgery. Corrected distance visual acuity was 20/25 or better in 63.6% (7 out of 11) eyes, and all cases with suboptimal visual outcome had coexisting posterior segment pathology (4 out of 11).

Retinal detachment after ICL implantation is attributed to high myopia, and may be observed in 0.57–1.75% cases.³ We observed retinal detachment and its sequelae in 36.4% (4 out of 11) cases, which required both ICL explant and phacoemulsification.

Visual rehabilitation is challenging in cases with ICL explant in one eye, with the crystalline lens in situ. We performed ICL exchange in two cases (chipped haptic and extremely high vault). A repeat ICL implantation was performed in the case with post-operative endophthalmitis 9 months after the successful resolution of endophthalmitis.⁵ However, in the case with uveitis, a repeat ICL implantation was not feasible in view of recurrent inflammatory episodes, and the patient was prescribed contact lens.

We implanted 714 ICLs over the last 10 years. In our case series with 11 cases of ICL explant, 6 cases had undergone a primary ICL implantation in our centre (Table 1).

To conclude, the indications of ICL explant can be varied. Cataract necessitating phacoemulsification is one of the major causes of ICL explant, especially in cases associated with posterior segment pathology. A low incidence of vault related complications was observed, with only 18.2% (2 out of 11) eyes requiring ICL explant for extremely high or shallow vault.