Implantable Collamer Lens Procedure Planning: A Review of Global Approaches.

More than 2 million implantable collamer lenses (ICLs) have been implanted worldwide. With a central port to improve aqueous flow through the ICL, the latest iteration of this phakic intraocular lens (pIOL) has been shown to have stable outcomes with very low rates of adverse events. However, correct planning and ICL size selection continue to be important to achieve an optimal vault. Shallow or excessive vaults are not complications in and of themselves but may increase the risk of complications. Historically, surgeons have relied on measurements of anterior chamber depth (ACD) and manual, caliper-measured white-to-white (WTW) distance to select the ICL size. New diagnostic and imaging technologies such as optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) provide additional opportunities for visualization and measurement of the intraocular dimensions involved in phakic intraocular lens implantation, including sulcus-to-sulcus (STS) and angle-to-angle (ATA) diameters. This paper reviews various approaches to ICL planning and sizing that have been published in the peer-reviewed literature, all of which produce acceptable results for predicting vault and size selection. Surgeons may also want to identify a methodology for patient evaluation and ICL size selection that best aligns with their personal preferences, diagnostic technology, and familiarity with analytical optimization tools.

Phakic intraocular lenses (pIOLs) are one method for correcting nearsightedness, with or without astigmatism. This category of refractive surgery has been growing rapidly in the US and around the world. Implantation of the implantable collamer lens (ICL), one type of pIOL, is safe and effective, with stable outcomes and low adverse event rates. When complications do occur, they are typically associated with an inappropriate vault, or distance between the implant and the natural lens. Preoperative planning and accurate ICL sizing are required to achieve an optimal vault and varies, depending on the diagnostic technology available to the surgeon. This paper reviews the current approaches to ICL planning and sizing in order to provide guidance to surgeons implanting this pIOL.

Decision taking in corneal refractive surgery.

A 27-year-old woman who wants to get rid of contact lenses and spectacles was seen at our clinic. She had strabismus surgery as a child and was patched for the right eye but now shows mild nondisturbing exophoria. Infrequently, she likes to box in the sports school. Her corrected distance visual acuity at presentation in the right eye was 20/16 with -3.75 -0.75 × 50 and in the left eye 20/16 with -3.75 -1.25 × 142. Her cycloplegic refraction in the right eye was -3.75 -0.75 × 44 and in the left eye was -3.25 -1.25 × 147. The left eye is the dominant eye. The tear break-up time was 8 seconds in both eyes, and the Schirmer tear test was 7 to 10 mm in right and left eyes, respectively. Pupil sizes under mesopic conditions were 6.62 mm and 6.68 mm. The anterior chamber depth (ACD) (measured from the epithelium) in the right eye was 3.89 mm and in the left eye was 3.87 mm. The corneal thickness was 503 µm and 493 µm of the right and left eye, respectively. Corneal endothelial cell density was on average 2700 cells/mm2 for both eyes. Slitlamp biomicroscopy showed clear corneas and a normal flat iris configuration. Supplemental Figures 1 to 4 (available at http://links.lww.com/JRS/A818, http://links.lww.com/JRS/A819, http://links.lww.com/JRS/A820, and http://links.lww.com/JRS/A821) show the corneal topography and Belin-Ambrósio deviation (BAD) maps at presentation of the right eye and left eye, respectively. Would you consider this patient a candidate for corneal refractive surgery (eg, laser-assisted subepithelial keratectomy, laser in situ keratomileusis [LASIK], or small-incision lenticule extraction [SMILE] procedure)? Has your opinion changed given the recent opinion of the U.S. Food and Drug Administration (FDA) regarding LASIK?1 The patient herself is slightly favoring an implantation of a phakic intraocular lens (pIOL), as she prefers something reversible. Would you implant a pIOL, and which type of IOL, for this level of myopia? What is your diagnosis or are additional diagnostic methodologies needed to establish a diagnosis? What is your treatment advice for this patient? REFERENCES 1. U.S. Food and Drug Administration, HHS. Laser-assisted in situ keratomileusis (LASIK) lasers-patient labeling recommendations; draft guidance for industry and food and drug administration staff; availability. July 28, 2022, Federal Register; 87 FR 45334. Available at: https://www.fda.gov/regulatory-information/search-fda-guidance-documents/laser-assisted-situ-keratomileusis-lasik-lasers-patient-labeling-recommendations Accessed January 25, 2023.

Impact on refractive surgery due to increasing use of personal protection equipment: Insights from EUROCOVCAT group.

Since the World Health Organization declared COVID-19 to be a pandemic on 11th March 2020, changes to social and sanitary practices have included significant issues in access and management of eye care during the COVID-19 pandemic. Additionally, the fear of loss, coupled with social distancing, lockdown, economic instability, and uncertainty, have led to a significant psychosocial impact that will have to be addressed. In the current COVID-19 pandemic, personal protective equipment such as face masks or face coverings have become a daily necessity. While "mass masking" along with hand hygiene and social distancing became more widespread, new issues began to emerge - particularly in those who wore spectacles as a means of vision correction. As we began to see routine patients again after the first lockdown had been lifted, many patients visited our clinics for refractive surgery consultations with a primary motivating factor of wanting spectacle independence due to the fogging of their spectacles as a result of wearing a mask. In this article, we report on new emerging issues in eye care due to the widespread use of masks and on the new unmet need in the corneal and cataract refractive surgery fields.

Outcomes of Conductive Keratoplasty Combined with Corneal Crosslinking in Advanced Ectatic Corneal Disease.

PURPOSE: To assess the effectiveness of a novel treatment for patients with advanced corneal ectasia and loss of visual acuity (VA). Conductive keratoplasty (CK) is performed to improve VA followed by epithelium-on (epi-on) corneal crosslinking (CXL) to stabilize the cornea after CK. METHODS: Retrospective, exploratory cohort study. Patients with keratoconus or postsurgical ectasia and best spectacle-corrected distance VA (CDVA) ≤ 20/40 were included. Conductive keratoplasty was performed (ViewPoint CK System, Refractec, Inc., Bloomington, MN); followed a day later by epi-on CXL (CXLUSA/CXLO, Bethesda, MD/CXLO Encinitas, CA). Measures included uncorrected distance visual acuity (UDVA) and CDVA, as well as refractive and tomographic measures and tomographic indices. RESULTS: Data from 50 eyes of 45 patients were analyzed. Mean follow-up was 15.1 ± 12.2 months (range: 2 to 51). Overall, UDVA and CDVA improved postoperatively. Subjective refraction and tomographic metrics did not show consistent changes, but changes in tomographic indices were associated with treatment follow-up time. At the 1-year visit, mean UDVA significantly improved over baseline (P = 0.009) by approximately 3 lines; mean CDVA improved significantly (P = 10-5) by approximately 2 lines. No eye lost lines of CDVA. Change in the Index of Surface Variance (ISV) was associated with treatment, and the D-Index trended over follow-up time. CONCLUSION: Conductive keratoplasty with a proprietary epi-on CXL treatment improved vision in patients with advanced ectasia This CK/epi-on CXL treatment offers the possibility of improved VA for patients with compromised vision due to ectasia.

Rethinking Elective Cataract Surgery Diagnostics, Assessments, and Tools after the COVID-19 Pandemic Experience and Beyond: Insights from the EUROCOVCAT Group.

The progressive deterioration of the visual function in patients on waiting lists for cataract surgery has a negative impact on their quality of life, especially in the elderly population. Patient waiting times for cataract surgeries in many healthcare settings have increased recently due to the prolonged stop or slowdown of elective cataract surgery as a result of coronavirus disease 19 (COVID-19). The aim of this review is to highlight the impact of such a "de-prioritization" of cataract surgery and to summarize some critical issues and useful hints on how to reorganize cataract pathways, with a special focus on perioperative diagnostic tools during the recovery phase and beyond. The experiences of a group of surgeons originating from nine different countries, named the European COVID-19 Cataract Group (EUROCOVCAT), have been combined with the literature and recommendations from scientific ophthalmic societies and healthcare institutions. Key considerations for elective cataract surgery should include the reduction of the number of unnecessary visits and examinations, adoption of precautionary measures, and implementation of telemedicine instruments. New strategies should be adopted to provide an adequate level of assistance and to guarantee safety conditions. Flexibility will be the watchword and regular updates would be necessary following scientific insights and the development of the pandemic.

Comparative Analysis of Swept-Source Optical Coherence Tomography and Partial Coherence Interferometry Biometers in the Prediction of Cataract Surgery Refractive Outcomes.

PURPOSE: To compare the accuracy of pre-operative corneal measurements obtained with four devices, and the refractive outcomes of two optical biometers. SETTING: Private practice. DESIGN: Retrospective. METHODS: Data taken from biometric measurements on 299 consecutive eyes prior to cataract surgery were retrospectively analyzed using the Argos SS-Optical Biometer and the Lenstar LS900 PCI optical biometer. As part of the standard cataract surgery pre-operative exam, patients also underwent placido disk topography and Scheimpflug tomography. Keratometry, anterior chamber depth, corneal diameter, pupil diameter, central corneal thickness and axial length were all measured. The comparable measurements were compared. Finally, for those eyes where cataract surgery was performed, the post-operative refractive results were compared to the predictive results of the two biometers. RESULTS: The SS-OCT Argos was able to measure all eyes, while five eyes could not be measured with the Lenstar LS900 PCI. Axial length measurements were performed only with the Argos and Lenstar devices. The eyes that could not be measured by the Lenstar LS900 PCI included dense grade IV nuclear sclerosis and large posterior subcapsular cataracts. In the primary endpoints, there was strong correlation between the Argos and the Lenstar devices in eyes with an axial length between 20 and 30 mm. CONCLUSION: The predictive accuracies of the Argos Optical Biometer and Lenstar LS900 PCI are similar, except in medium and long eyes, in which the predictive accuracy of Argos SS-OCT biometry was higher. The Argos system was found easier to use by technicians when compared to the other biometry devices.

Optimizing Corneal Cross-Linking in the Treatment of Keratoconus: A Comparison of Outcomes After Standard- and High-Intensity Protocols.

PURPOSE: To evaluate and compare the safety and efficacy of accelerated (AXL) and standard corneal cross-linking (CXL) protocols in patients with progressive keratoconus. METHODS: Progressive keratoconus patients (14-40 years) received either standard-intensity CXL or high-intensity CXL (AXL). Corneas were exposed to ultraviolet-A 365 nm light for 30 minutes at an irradiance of 3.0 mW/cm in the standard CXL group and to ultraviolet-A 365 nm light for 10 minutes at 9.0 mW/cm in the AXL group. Changes in uncorrected visual acuity, best spectacle-corrected visual acuity, refractive astigmatism, Kmax, and Kmean were used to determine treatment efficacy. Safety was determined by the incidence of adverse events and occurrence of loss of 2 or more lines of best spectacle-corrected visual acuity. Outcomes for CXL versus AXL were compared to determine differences in safety and efficacy between treatment groups. RESULTS: Thirty-six eyes of 34 patients (mean age, 27.9 ± 7.6 years) underwent AXL; 66 eyes of 53 patients (mean age, 30.0 ± 8.0 years) underwent standard-intensity CXL. There was no significant difference in any outcome measures between the groups. For AXL, there seemed to be more corneal flattening, with a statistically significant reduction in Kmean at 6 and 12 months postoperatively, when compared preoperatively (P < 0.01). There were no adverse events or complications in any patients. CONCLUSIONS: There was more corneal flattening in AXL patients 6 to 12 months postoperatively, suggesting that AXL may be a promising alternative to CXL in stabilizing corneal ectasia.

Agreement Between Predicted and Measured Ablation Depth After Femtosecond Laser-Assisted LASIK for Myopia.

PURPOSE: To investigate agreement between the predicted ablation depth calculated by the EX500 excimer laser (Wavelight Laser Technologie AG, Erlangen, Germany) and the measured ablation depth in eyes that have undergone femtosecond laser-assisted LASIK (FS-LASIK) for myopia. METHODS: Corneal thickness was measured with a rotating Scheimpflug camera preoperatively and 3 months postoperatively and the difference between these values was defined as the measured ablation depth. The difference between the predicted and the measured ablation depth was defined as the difference in ablation depth (ΔAD). RESULTS: In 85 eyes of 85 patients, no statistically significant difference was detected between the mean predicted ablation depth (66.33 ± 24.15 µm) and the measured ablation depth at the thinnest corneal location (67.04 ± 30.94 µm), the corneal apex (67.52 ± 31.22 µm), or the pupil center (67.73 ± 31.48 µm). Bland-Altman plots revealed moderate agreement for measurements at the thinnest point (95% limits of agreement [LoA]: -25.13 to 23.70 µm), corneal apex (95% LoA: -24.70 to 22.33 µm), and pupil center (95% LoA: -25.30 to 22.51 µm), with a proportional bias between the average ablation depth and ΔAD. The predicted ablation depth was overestimated in eyes with lower correction and underestimated in eyes with higher correction. CONCLUSIONS: Moderate agreement between the predicted and measured ablation depth warrants caution when planning myopic FS-LASIK and calculating the residual bed thickness and percent tissue altered. When higher amounts of correction are planned, the laser software may underestimate the predicted ablation depth.

The theory and art of corneal cross-linking.

Before the discovery of corneal cross-linking (CXL), patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs) that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL) would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A) light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.

Newer protocols and future in collagen cross-linking.

Corneal Cross-Linking (CXL) is an established surgical procedure for the treatment of corneal disorders such as corneal ectasia and keratoconus. This method of treatment stabilises the corneal structure and increases rigidity, reducing the requirement for corneal transplantation. Since its development, many scientific studies have been conducted to investigate ways of improving the procedure. Biomechanical stability of the cornea after exposure to UV-A light, and the effect of shortening procedure time has been some of the many topics explored.

Optical ray tracing-guided myopic laser in situ keratomileusis: 1-year clinical outcomes.

PURPOSE: To compare the safety, efficacy, and predictability of laser in situ keratomileusis treatments at 1 year postprocedure using a novel geometric ray tracing algorithm with outcomes of treatments using wavefront-optimized, wavefront-guided, and topography-guided ablation profiles of an excimer laser (WaveLight GmbH, Erlangen, Germany; Alcon Laboratories, Fort Worth, TX, USA). SETTING: Wellington Eye Clinic, Dublin, Ireland. DESIGN: Retrospective comparative case series. METHODS: Eyes having a preoperative myopic spherical equivalent refractive error >4.00 D and/or astigmatism between 2.00-6.00 D resulting in a spherical equivalent power greater than -4.00 D received laser in situ keratomileusis treatments using a ray tracing algorithm. Refractive outcomes were analyzed postoperatively at 6 and 12 months and were compared to outcomes of wavefront-optimized, wavefront-guided, and topography-guided treatments in eyes with the same pretreatment refractive range. RESULTS: Forty-seven eyes of 26 patients were treated using the ray tracing algorithm. At 12 months postprocedure, uncorrected visual acuity was better than the preoperative best-corrected visual acuity in this group. The percentage of eyes achieving an uncorrected visual acuity or best-corrected visual acuity ≥20/20 significantly exceeded the rates achieved in the wavefront-optimized and topography-guided groups. A greater percentage of eyes achieved an uncorrected visual acuity ≥20/20 and ≥20/16 in the wavefront-guided group, but no eyes in the wavefront-guided group had an uncorrected visual acuity ≥20/12.5 in comparison to 9.5% of eyes in the ray tracing group. CONCLUSION: This study provides further evidence of the safety, efficacy, and predictability of laser in situ keratomileusis outcomes using an optical ray tracing algorithm to treat moderate to high myopic astigmatism and shows that good results are sustained through 1 year.

Predictability of corneal flap thickness in laser in situ keratomileusis using a 200 kHz femtosecond laser.

PURPOSE: To compare the intended versus the resultant thickness of laser in situ keratomileusis (LASIK) flaps created with a new femtosecond laser and to report the 3-month postoperative refractive outcomes. SETTING: Wellington Eye Clinic, Dublin, Ireland. DESIGN: Retrospective consecutive case series. METHODS: A consecutive series of eyes having LASIK flaps created using a Wavelight FS200 femtosecond laser were included in this analysis. Eyes with preoperative spherical equivalent (SE) myopic refractive errors up to -12.00 diopters (D), hyperopic refractive errors up to +5.50 D, and astigmatism up to 6.00 D received primary LASIK. Outcomes included postoperative flap thickness and 3-month postoperative refraction. RESULTS: Outcomes in 431 eyes of 258 patients having LASIK with femtosecond flap creation were assessed. With an intended flap thickness of 120 µm, the mean post-LASIK flap thickness was 120.23 µm ± 13.94 (SD). In 349 of 813 eyes, EX500 optical pachymetry measurements were compared with Scheimpflug pachymetry readings. The mean corneal thickness was 553.52 ± 29.81 µm with optical pachymetry and 553.39 ± 29.12 µm with the Pentacam rotating Scheimpflug camera. In 162 eyes, the flap thickness was measured with optical coherence tomography; the mean was 121.94 ± 10.52 µm. Achieved flap dimensions were as intended. CONCLUSIONS: This study provides evidence of the predictability and lower variability of LASIK flaps created using the femtosecond laser. Consecutive patients having LASIK had good, predictable, and stable outcomes at the 3-month mark.

Outcomes after topography-based LASIK and LASEK with the wavelight oculyzer and topolyzer platforms.

PURPOSE: To explore the efficacy, safety, and predictability of topography-guided laser epithelial keratomileusis (LASEK) and LASIK treatments using the ALLEGRO Oculyzer (rotating Scheimpflug image-based) as compared to the ALLEGRO Topolyzer (Placido disk-based) platform (WaveLight AG). METHODS: In this retrospective, non-comparative case series, 72 eyes were treated using Oculyzer data and 71 eyes were treated using Topolyzer data. Seventy-nine men and 64 women ranging in age from 21 to 63 years were included in the study. The 6-month postoperative uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA) of patients were compared to the preoperative values. The data analysis was stratified based on the preoperative refractions, separating patients into three categories: myopes, hyperopes, and mixed astigmatics. RESULTS: Of the preoperative myopes in the Oculyzer group, 76% remained the same, 5% lost 1 line, 14% gained 1 line, and 5% gained 2 lines of visual acuity at 6 months. In the Topolyzer group, 69% remained the same, 25% gained 1 line, and 6% gained 2 lines of BSCVA. Using the Oculzyer, 95% of myopes, 80% of hyperopes, and 60% of patients with mixed astigmatism were within 10.50 diopters (D) of target refraction. Using the Topolyzer, 88% of myopes, 78% of hyperopes, and 50% of patients with mixed astigmatism were within +/- 0.50 D of target. The outcomes of the preoperative hyperopes and patients with mixed astigmatism are similarly reported. The difference in outcomes between the Oculyzer and Topolyzer cohorts in the myopes and patients with mixed astigmatism was not statistically significant. In the hyperopes, patients treated with the Oculyzer had superior UCVA to those treated with the Topolyzer platform. CONCLUSIONS: This case series demonstrates that the Oculyzer and Topolyzer are both effective tools in topography-guided corneal excimer laser surgery. In myopes and patients with mixed astigmatism, both systems were comparable in efficacy and safety. In the hyperopes, the resultant UCVA in the Oculyzer cohort was slightly superior.