Intraocular lens explantation occurs in less than 1% of all cataract surgeries. The main reason for IOL removal is late dislocation of IOL due to zonular weakness. Other rare indications are IOL decentration, IOL opacification, incorrect IOL power, glare, and chafing syndrome5,6. Moreover, patients with multifocal IOL (MFIOL) implantation have higher expectations and dissatisfaction of postoperative quality of vision and occasional refractive surprises necessitating spectacle wear are often unacceptable to these patients7. Kamiya et al reported a series of 50 eyes of unhappy patients that underwent MFIOL explantation. Their survey showed that the most common reasons for MFIOL explantation were decreased contrast sensitivity, followed by photic phenomenon, unknown origin including neuroadaptation failure, incorrect IOL power, preoperative excessive expectation, IOL dislocation/decentration, and anisometropia7.
IOL opacification has been observed as an isolated phenomenon for polymethylmethacrylate (PMMA) and silicone materials or serially for acrylic materials mostly hydrophilic. Gartaganis et al8 demonstrated the calcification pattern of the hydrophilic IOL with a hydrophobic surface (Lentis LS-502-1) and they concluded that despite the hydrophobic surface, calcification can be developed from the hydrophilic subsurface of the IOL. This is in line with our laboratory investigation, which confirmed calcium depositions in explanted Lentis surface. They also noted that patients that underwent a combine phacoemulsification and pars plana vitrectomy (PPV) with silicone oil injection had the shortest intervals of IOL opacification, despite the intact posterior capsule and subsequently no direct contact between the IOL and the silicon oil. In our case series we did not have any combined procedures or any post-phacoemulsification PPV.
Opacification of hydrophilic IOL of various lens designs have been reported over the past twenty years9–14. This can be categorised into primary and secondary or false calcification. Primary IOL calcification can occur due to a variety of reasons, including improper formulation of the polymer, faulty packaging, forceps-related impressions, IOL fabrications and the presence of certain viscoelastic substances14. This calcification appears to be either in the surface of the IOL or in the substance of the lens. Secondary calcification is thought to be induced by intracameral gas (sulphur hexafluoride or perfluoropropane) or air, during Endothelial Keratoplasty (EK) surgery15 or simply a remnant of gas. The proposed mechanism is that the gas bubble induces local damage to the exposed IOL optic surface, which may protrude through the pupillary aperture16.
All our cases are considered as primary IOL opacification. This is similar to the outcome of other studies, where the vast majority developed primary IOL opacification17,18. The time of opacified Lentis explantation in our department varied from 4 to 8 years postoperatively (64.5 ± 16.7 months). This interval time is relatively close to Gurabardhi et al report of 49 ± 14.4 months, but much longer than Bompastor-Ramos et al 29.15 ± 9.57. This may suggest a delay in the initial diagnosis as few patients referred from other hospitals or a possible misdiagnosis particularly in patients that have been referred following ‘unsuccessful’ YAG laser capsulotomy.
In our study, visual acuity improved in all eyes following IOL exchange, despite the challenges. Importantly, none of our patients were left aphakic and they all had IOL explantation and secondary lens implantation in one procedure. Interestingly, 3 out of 5 eyes that had within the bag secondary lens were implanted with a multifocal IOL, while in two eyes with previous YAG laser capsulotomy one IOL was placed in the sulcus and the other one in the anterior chamber. This highlights the importance of preserving the capsular bag before and during IOL exchange to maximise the chance of in the bag implantation. In previous series comorbidities such as diabetes, glaucoma, and uveitis were considered as risk factors19–21. In our sample there were no significant comorbidities and we did not record any early or late postoperative complications, but this is likely to be limited by the small number of subjects and relatively young patients’ age.
In conclusion, IOL exchange for multifocal IOL opacification improved visual acuity in all our subjects. Surgical planning must take into account capsular bag status and the impossibility of in-the-bag IOL implantation. Moreover, when consenting patients for such procedures, patients must be warned of additional risks of zonular dialysis, vitreous loss, retinal detachment and need for potential ACIOL with its associated sequel of complications. It is also important to remember that YAG laser posterior capsulotomy should be considered carefully if there is a suspicion of IOL opacification, as it makes certain the need for anterior vitrectomy thus increasing the risk of retinal detachment after surgery and restricts the surgical options of secondary IOL implantation including in-the-bag IOL exchange with MFIOL.