Reasons for explantation of phakic intraocular lenses and associated perioperative complications: cross-sectional explant registry analysis

Vertical implantable collamer lens as a novel method to increase rotational stability

PURPOSE

We investigated the vertical implantation of a toric implantable collamer lens (ICL) and compared the rotational stability with that of horizontal implantation.

METHODS

This matched comparative study retrospectively reviewed and analyzed data from patients who underwent ICL implantation from 2003-2022 by 1:1 matching vertical and horizontal (V and H toric groups, respectively) implantation patients according to preoperative astigmatism, spherical equivalent, sulcus-to-sulcus, anterior chamber depth, and ICL size. Visual acuity, manifest refraction, vaulting, and rotation were measured 3 months postoperatively.

RESULTS

We included 646 eyes (323 each in the V and H toric groups). No statistically significant difference was observed between groups in postoperative visual acuity, refractive error, and astigmatism. Vaulting was lower in the V toric group. (P < 0.001). The mean lens rotation in the V toric group was less than that in the H toric group (1.11 ± 2.84° versus 3.02 ± 10.34°, P = 0.001). The proportion of eyes in the V and H toric groups showing ≥10° of rotation was 2.5% (8 eyes) and 6.5% (21 eyes), respectively (P = 0.014). Despite repositioning from rotation, three (0.9%) and eight (2.5%) eyes required removal owing to lens re-rotation in the V and H toric groups, respectively.

CONCLUSION

Toric ICL vertical implantation showed good rotational stability, and appropriate visual acuity correction results with relatively low vaulting. This procedure therefore presents an effective novel method that could replace horizontal toric ICL implantation.

Endothelial Cell Loss in Patients with Phakic Intraocular Lenses

Although the safety of phakic intraocular lenses (pIOLs) has been continuously improved over 70-years of development, high endothelial cell losses can occur even with current pIOL models. Numerous studies have demonstrated that the distance of a pIOL to the corneal endothelium plays a crucial role in the extent of endothelial cell loss. For this reason alone, higher endothelial cell loss tends to be observed with anterior chamber lenses than with posterior chamber lenses. Adequate preoperative anterior chamber depth is essential, at least for iris-fixed pIOLs, in order to ensure a safe distance from the endothelium. However, the anterior chamber becomes shallower with age and therefore it may be useful to consider patient age in the safety criteria. Although endothelial cell loss is generally low with current pIOL models, regular monitoring of the endothelial cell density remains essential due to large interindividual differences in patients with pIOLs. If the endothelial cell loss is greater than expected and the follow-up visits confirm the trend, the pIOL should be explanted without delay. The endothelial reserve should be considered on an individual basis by taking into account patient age, physiological endothelial cell loss, and loss due to further surgery. With careful indication and long-term patient care, pIOLs remain a safe treatment option.

Causes and outcomes of implantable collamer lens explantation in patients with corneal endothelial cell loss

PURPOSE

To investigate the correlated factors of corneal endothelial cell density (ECD) loss and ECD change in implantable collamer lens (ICL) explantation patients.

SETTING

Seoul St. Mary's Hospital, Seoul, South Korea.

DESIGN

Retrospective analysis.

METHODS

The study cohort consisted of 93 eyes from 50 patients who underwent ICL explantation. Correlation analysis was performed to assess the ocular parameters associated with ECD loss, while percentage of ECD change (ΔECD%) was monitored up to 6 months postoperatively. Receiver operating characteristic (ROC) curve was used to set cutoff values of ocular parameters to prevent ECD loss after explantation.

RESULTS

In multiple regression analysis, high vaulting, high vaulting/anterior chamber depth (ACD), low anterior chamber angle (ACA), and high iris pigmentations are the significant factors of ECD loss. At postoperative 6 months, 14 eyes (15.1%) had decrease (10.5% loss), 47 eyes (51.0%) were stationary, and 32 eyes (34.4%) had increase (12.7% gain) of ECD. The ROC curve analysis showed that vaulting had the highest area under the curve (AUC = 0.822), followed by vaulting/ACD (AUC = 0.821), ECD (AUC = 0.753), and ACA (AUC = 0.723) (all P < .01). Preoperative ECD showed a sensitivity of 77.6% and specificity of 86.7% in preventing ECD loss after explantation, with a cutoff value of 1722 cells/mm 2 , as determined by ROC curve analysis.

CONCLUSIONS

Our study demonstrated that high vaulting is a significant factor in ECD loss among ICL-inserted patients. To prevent continuous ECD loss in ICL patients, close monitoring of ECD and making appropriate decisions regarding explantation may be necessary.

Diagnostic Techniques to Increase the Safety of Phakic Intraocular Lenses

Preoperative and postoperative diagnostics play an important role in ensuring the safety of patients with phakic intraocular lenses (pIOLs). The risk of endothelial cell loss can be addressed by regularly measuring the endothelial cell density using specular microscopy and considering the endothelial cell loss rate and the endothelial reserve in accordance with the patient's age when deciding whether to explant a pIOL. The anterior chamber morphometrics, including the anterior chamber depth and the distance between the pIOL and the endothelium, measured using Scheimpflug tomography and anterior segment optical coherence tomography (AS-OCT), can help to assess the risk of the endothelial cell loss. In patients undergoing posterior chamber pIOL implantation, accurate prediction of the vault and its postoperative measurements using AS-OCT or Scheimpflug tomography are important when assessing the risk of anterior subcapsular cataract and secondary glaucoma. Novel approaches based on ultrasound biomicroscopy and AS-OCT have been proposed to increase the vault prediction accuracy and to identify eyes in which prediction errors are more likely. Careful patient selection and regular postoperative follow-up visits can reduce the complication risk and enable early intervention if a complication occurs.

Evaluation of Ocular Diameter Parameters Using Swept-Source Optical Coherence Tomography

Purpose: To investigate the iridocorneal angle-to-angle (ATA), sclera spur-to-sclera spur (STS), and white-to-white (WTW) ocular diameters and their potential influence on anterior chamber intraocular lens (ACIOL) and implantable collamer lens (ICL) sizing in Chinese subjects by using a swept-source optical coherence tomography system (SS-OCT). Design: A retrospective, observational, cross-sectional study. Methods: In 60 right eyes (60 subjects), the ATA, STS, and WTW were measured in six axes (0°-180°, 30°-210°, 60°-240°, 90°-270°, 120°-300°, and 150°-330°) using SS-OCT. The ACIOL and ICL sizes were calculated based on horizontal and vertical axes anterior segment data. A paired sample t-test was used to test the differences in each parameter across the six axes, the potential difference between each pair of parameters in a given axis, and the artificial lens size difference between the horizontal and vertical directions. Pearson's correlation analysis was used to determine the potential correlation between age and AL, WTW, STS, and ATA distances. Results: ATA and STS were the longest on the vertical and shortest on the horizontal axis, while WTW was similar on both axes. These three parameters differed only in the vertical axis (F = 4.910, p = 0.008). ATA and STS were by 0.23 ± 0.08 mm (p = 0.005) and 0.21 ± 0.08 mm wider (p = 0.010) than WTW, respectively. ICL size was 0.27 ± 0.23 mm smaller when based on the horizontal than on the vertical axis parameters (p < 0.001), while ACIOL remained similar (p = 0.709). Age correlated negatively and axial length positively with all measured values. ATA, STS, and WTW correlated positively in the same axis (all p < 0.001). Conclusions: ATA and STS were longer in the vertical than in the horizontal direction, while WTW measurements remained similar. ATA and STS diameters more accurately depicted anatomic relationships for phakic IOL sizing than WTW.

Descemet’s Membrane Endothelial Keratoplasty for Corneal Endothelial Failure Secondary to Three Types of Phakic Intraocular Lens – Retrospective Study

Purpose

To analyze the outcomes of Descemet's membrane endothelial keratoplasty (DMEK) for corneal endothelial failure secondary to phakic intraocular lens implantation (PIOL) at a reference center for corneal transplantation in Spain.

Design

Retrospective, single-surgeon case series.

Methods

Single-center analysis of patients who underwent DMEK for PIOL-related corneal decompensation between July 2011 and July 2020 with at least 6 months of follow-up postoperatively. Primary outcome was final best-corrected visual acuity (BCVA, logMAR) compared to pre-DMEK BCVA. Secondary outcomes analyzed included post-DMEK refractive spherical equivalent, endothelial cell loss (%ECL), and graft failure.

Results

Sixteen eyes (14 patients) underwent DMEK for PIOL-related corneal decompensation. Mean (SD) time to PIOL explantation was 9.3 (5.0) years, and median (P25-P75) time between PIOL explantation and DMEK surgery was 3 (2-4) months. Median pre-DMEK BCVA was 0.80 (1.08-0.60) logMAR. A statistically significant improvement in BCVA was observed 1 month after DMEK (p = 0.001), and median final BCVA was 0.15 (0.0-0.35) logMAR (p = 0.002). Mean %ECL was 55.6 (18.7) % at 2-year follow-up and 61.7 (11.7) % in eyes with over 4 years of follow-up. Two eyes required re-bubbling (12.5%), one of which ended in primary graft failure (6.2%) and one eye had late endothelial graft failure (LEGF) at 4-year follow-up (1/15 grafts, 6.7%).

Conclusion

In patients with PIOL-related corneal decompensation, DMEK leads to good and clinically significant refractive and visual outcomes in the medium-long term, with a good safety profile. Prospective studies are encouraged to ascertain whether these cases are at increased risk of accelerated endothelial cell loss and LEGF.

Accuracy of Intraocular Lens Calculation Formulas in Patients Undergoing Combined Phakic Intraocular Lens Removal and Cataract Surgery

PURPOSE

To investigate the prediction accuracy of intraocular lens (IOL) calculation formulas, and the impact of anterior chamber depth (ACD) and lens thickness (LT) measurement errors on IOL power calculation in patients undergoing combined phakic IOL (PIOL) removal and cataract surgery.

DESIGN

Retrospective, consecutive case series study.

METHODS

Thirty-six PIOL implanted eyes (12 anterior chamber PIOLs and 24 posterior chamber PIOLs [PC-PIOL]) undergoing cataract surgery were included. The prediction accuracy of new formulas (Barrett universal II, Emmetropia verifying optical, Kane, and Ladas super formula) and traditional formulas (Haigis, Hoffer Q, Holladay 1 and SRK/T) with or without Wang-Koch (WK) axial length (AL) adjustment was evaluated. The influence of ACD and LT measurement errors of IOLMaster 700 on refractive outcomes was also investigated.

RESULTS

The Kane and traditional formulas with WK AL adjustment had no significant systematic prediction error and displayed a smaller median absolute error, whereas the other formulas showed significant hyperopia shift (P < .05) and relatively lower prediction accuracy. The accuracy rate of IOLMaster 700 in measuring the ACD and LT was 100% in eyes with anterior chamber PIOL implantation, and 37.50% in the PC-PIOL subgroup. No significant difference was observed in refractive outcomes of formulas using correct and wrong parameters in the PC-PIOL subgroup (P > .05).

CONCLUSIONS

The Kane and traditional formulas with WK AL adjustment exhibited relatively higher prediction accuracy in patients who underwent combined PIOL removal and cataract surgery. The IOLMaster 700 displayed low accuracy in ACD and LT measurements for PC-PIOL implanted eyes, but showed negligible impact on IOL prediction accuracy.

Indications for exchange or explantation of phakic implantable collamer lens with central port in patients with and without keratoconus

AIM

To evaluate the causes of phakic implantable collamer lens (ICL) exchange/explantation in patients with and without keratoconus (KC) at two tertiary hospitals in Riyadh, Saudi Arabia.

METHODS

A retrospective chart review of all patients who underwent ICL (model V4c with central port) exchange/explantation was performed using the electronic medical record systems. All available preoperative and postoperative data were documented for each patient.

RESULTS

Over 7y, 2283 ICL implantation procedures were performed; 46 implants (2%) required exchange (21 implants)/explantation (25 implants), of which 14 cases (30.4%) were patients with KC. Indications for ICL exchange/explantation in non-KC group were vault measurement, cataract formation, increased intraocular pressure, inaccurate refraction, and patient dissatisfaction in 22 (68.75%), 4 (12.5%), 3 (9.37%), 2 (6.25%), and 1 (3.12%) case, respectively. The most common indication for ICL exchange/explantation in the KC group was inaccurate vault sizing in 11 patients (78.57%), inaccurate refraction in 2 patients (14.28%), and patient dissatisfaction postoperatively in 1 (7.14%) case.

CONCLUSION

ICL implantation results in predictable refractive outcomes over the long term with exchange/explantation rates comparable to previous literature. Improper vault size is the most common cause of ICL exchange/explantation among patients with or without KC.

Current Developments in Corneal Topography and Tomography

Introduction: Accurate assessment of the corneal shape is important in cataract and refractive surgery, both in screening of candidates as well as for analyzing postoperative outcomes. Although corneal topography and tomography are widely used, it is common that these technologies are confused. The aim of this study was to present the current developments of these technologies and particularly distinguish between corneal topography and tomography. Methods: The PubMed, Web of Science and Embase databases were the main resources used to investigate the medical literature. The following keywords were used in various combinations: cornea, corneal, topography, tomography, Scheimpflug, Pentacam, optical coherence tomography. Results: Topography is the study of the shape of the corneal surface, while tomography allows a three-dimensional section of the cornea to be presented. Corneal topographers can be divided into large- and small-cone Placido-based devices, as well as devices with color-LEDs. For corneal tomography, scanning slit or Scheimpflug imaging and optical coherence tomography may be employed. In several devices, corneal topography and tomography have been successfully combined with tear-film analysis, aberrometry, optical biometry and anterior/posterior segment optical coherence tomography. Conclusion: There is a wide variety of imaging techniques to obtain corneal power maps. As different technologies are used, it is imperative that doctors involved in corneal surgery understand the science and clinical application of devices for corneal evaluation in depth.