Corneal Endothelial Changes After Phakic Intraocular Lens Explantation Combined With Cataract Surgery: 24 Month Follow-Up Study

Phakic intraocular lens (pIOL) implantation is a safe and effective surgery, providing stable refractive outcomes for decades. Corneal endothelial cell loss is an important and well documented complication of pIOL implantation and one of the main causes of explantation. Phakic IOL explantation, especially when performed due to endothelial loss and when combined with cataract surgery, is feared by surgeons due to the theoretically greater endothelial loss. However, there is little evidence regarding the long-term behavior of endothelial cells after this surgery. Therefore, the purpose of this study was to characterize the qualitative and quantitative changes in endothelial cells after pIOL explantation combined with cataract surgery.

Refractive Surgery Unit of the Ophthalmology Department of Unidade Local de Saúde de Santo António (ULSSA), a tertiary hospital in Oporto, Portugal.

We retrospectively reviewed all patients submitted to pIOL explantation combined with standard cataract surgery from January 2010 to December 2021 with 24 months of minumum follow-up. Surgical technique consisted of a superior corneal incision which was used for pIOL explantation and for cataract surgery. For each eye we evaluated the type of IOL, indication for explantation and endothelial cell morphology (cell density - CD - cells/mm², average cell area -AVG - μm², coefficient of variation and percentage of hexagonal cells) preoperatively and at 1, 6, 12 and 24 months postsurgery. Data was obtained using the KONAN® Noncon Robo-CA SP-8800 specular microscope (Konan Eletric Co., Japan) and analysed using SPSS (SPSS statistics, Somers, NY). 

178 eyes of 101 patients were included. 70.2% of eyes had Artisan Myopia 206 pIOL implanted. Two groups were created according to motive of pIOL explantation: cataract (G1, n= 123, 47.7%) and endothelial cell loss (G2, n=120, 46.5%). Preoperatively, G2 had significantly lower CD(1953.1±509.0  vs. 1038.4±427.0,p=0.001) and higher AVG(556.2±196.9 vs. 1114.1±420.0,p=0.001). G1 maintained a stable CD (1752.6±497.8, 1695.6 ± 513.0, 1598.4 ± 411.5, 1658.7±489.6, 1 to 24 months). G2 showed postoperative decline in CD (949.2±319.2) and increase in AVG (1125.9±484.6) until 6 months with posterior recovery from 12 months onwards (CD: 1192.9±391.6, p= 0.073, 1235.1±491.2, p= 0.239; AVG: 931.9±306.4, p= 0.017, 927.6±335.6, p=0.065 at 12 and 24 months).

Phakic IOL explantation combined with cataract surgery is safe in the long term, even when the reason for the explantation is the endothelial cell loss.
More than that, eyes with worse endothelial cell counts seem to have a progressive improvement in both quantitative and qualitative parameters. These results suggest that the endothelial balance between regeneration and aggression can be modified after pIOL explantation. We postulate that the reduction in recognized factors for endothelial damage, including trauma-related and chronic subclinical inflammatory responses, might be playing a role in this post explant improvements in corneal endothelium.