Predictors Of Endothelium Behaviour After Phakic Intraocular Lens Explantation Combined With Cataract Surgery

Phakic intraocular lens (pIOL) implantation is a well-established procedure that provides stable refractive outcomes, but corneal endothelial cell loss (ECL) remains a complication, often necessitating explantation. This concern is heightened when combined with cataract surgery due to the risk of further endothelial damage. Despite this, limited evidence exists on factors influencing long-term endothelial cell (EC) behaviour post-surgery. This study aims to identify the key predictors of endothelial cell response 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.

All patients submitted to pIOL explantation combined with cataract surgery from January 2021 to February 2024 with 12 months of minimum follow-up were reviewed. Endothelial cell morphology (cell density(CD), average cell area(AVG), coefficient of variation(CV), % of hexagonal cells(6A), area of the largest (MAX) and smallest (MIN) cell) pre-explantation and at 1, 6 and 12 months after surgery were evaluated. Data was obtained using the Tomey EM-4000 (Tomey, Nürnberg). A multivariate analysis was conducted to determine significant predictors of EC response.

72 eyes of 68 patients (51.5±5.5 years old) were analysed. Preoperative CD was 1545± 544, with 62.5%(n=45) patients presenting with EC loss (mean: -14.4%/year), while 37.5%(n=27) presented with EC gain (ECG) (mean: 17.9%/year) at the 1 year follow-up. Preoperatively, the EC gain group had a tendency to lower CD (1409.4 vs 1627, p=0.1) and CV (39.2 vs 42.2, p=0.12) but higher MAX (1851 vs 1501.2, p=0.08), MIN (226.8 vs 113.2, p=0.07), AVG (842.6 vs 685, p=0.03) and 6A (42.3 vs 38.9, p= 0.08). Multivariate logistic regression analysis revealed that preoperative CV and MAX explained 72% of the variance in EC gain (R² = 0.113, p =0.005), with CV≥ 40% and MAX≤  2000µ² associating with a higher chance of EC loss.

Preoperative higher CV and lower MAX are associated with higher chances of EC loss up to one year after pIOL explantation, implying that endothelial cell morphology, rather than just CD plays a crucial role in postoperative endothelial behaviour. These results can explain why eyes with the same CD in the preoperative period evolved differently in the postoperative period and can help to decide the safest time for explantation, taking into account not only the counts but also the morphology of the cells.