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.

COVID-19 outbreak and increased risk of amblyopia and epidemic myopia: Insights from EUROCOVCAT group.

The most common cause of vision impairment in children is amblyopia. It is defined as impaired visual acuity in one or both eyes that is present with no demonstrable abnormality of the visual pathway and is not immediately resolved by wearing glasses. After the World Health Organization (WHO) recognized COVID-19 as a global pandemic on March 11, 2020, widespread changes and restrictions to social and sanitary practices have presented significant issues in access to eye care during the COVID-19 pandemic. A reduction of more than 80% in pediatric eye care volume up to its total cessation has been observed in different departments. In this scenario, reduced or absent eyesight, due to delay in timely treatment of amblyopic conditions, could create major, long-lasting effects on all aspects of life, including daily personal activities, interacting with the community, school and work opportunities and the ability to access public services. Processes coming out of lockdown should be gradually easing restrictions giving priority to ophthalmology and eye care facilities so that amblyopia does not remain unattended and irreversible as in adults due to lack of timely treatments. If not reversible, this process could lead to a dramatic increase in disability and unsustainable social costs for many governments.

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.

Early impact of COVID-19 outbreak on eye care: Insights from EUROCOVCAT group.

The recent outbreak of coronavirus disease 2019 (COVID-19) has been declared a public health emergency worldwide. The scientific community has put in much effort and published studies that described COVID-19's biology, transmission, clinical diagnosis, candidate therapeutics, and vaccines. However, to date, only a few data are available on the impact of COVID-19 pandemic on ophthalmological care in different health care systems, its future consequences in terms of disability, and access to sight-saving cures for many patients. To reduce human-to-human transmission of the virus and also ensure supply of infrastructures, human resources, and disposable medical devices to many regions, it is crucial to assess risks and postpone non-essential outpatient visits and elective surgical procedures, especially in older patients and those with comorbidities. This delay or suspension in essential eye procedures may cause significant and rapid vision impairment to irreversible blindness. Determining the risk-benefit profile of treating these ocular pathologies is a public health issue of supreme priority, even though many patients benefiting from therapeutic treatments are elderly, who are more vulnerable to COVID-19. If not reversible, this process could lead to a dramatic increase in disability and unsustainable social costs for many Governments.

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.

Prospective Evaluation of Outcomes in Patients Undergoing Treatment for Myopia Using the WaveLight Refractive Suite.

PURPOSE: To evaluate outcomes in patients with myopia up to -12.00 diopters (D), with or without astigmatism up to 6.00 D, who underwent LASIK with the WaveLight Refractive Suite (Alcon Laboratories, Inc., Fort Worth, TX). METHODS: This multicenter, prospective, single-arm study evaluated patients at baseline, on the day of surgery, and 1 day and 1, 3, and 6 months postoperatively. The primary outcome was comparison of 1-month postoperative binocular uncorrected distance visual acuity (UDVA) with preoperative binocular corrected distance visual acuity (CDVA). Noninferiority was defined as the upper bound of the 95% confidence interval less than 0.1 logMAR. Post-hoc analyses for superiority were conducted for monocular and binocular CDVA at 1, 3, and 6 months. Continuous variables were summarized using mean (95% confidence interval), median, quartiles, standard deviation, minimum and maximum, and categorical variables as counts and percentages. RESULTS: Of the 96 patients (54% female, mean age: 31 years), 5 underwent monocular and 91 binocular LASIK surgery (187 eyes). Preoperatively, mean binocular CDVA was -0.025 ± 0.126 logMAR, mean binocular UDVA was 1.148 ± 0.626 logMAR, and mean manifest spherical refraction equivalent was -3.67 ± 1.98 D. Postoperative binocular UDVA at 1 month (-0.088 ± 0.107 logMAR) was noninferior to preoperative binocular CDVA. Postoperative binocular UDVA at 1, 3 (-0.098 ± 0.107 logMAR), and 6 months (-0.105 ± 0.113 logMAR) were significantly superior to preoperative binocular CDVA (P < .0001 each). CONCLUSIONS: The primary study objective was exceeded; postoperative UDVA was significantly superior to preoperative CDVA in patients with myopia and myopia with astigmatism who underwent LASIK with the WaveLight Refractive Suite. [J Refract Surg. 2017;33(5):322-328.].

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.

Second-harmonic reflection imaging of normal and accelerated corneal crosslinking using porcine corneas and the role of intraocular pressure.

PURPOSE: The aim of this study was to investigate morphological changes, using second-harmonic (SH) optical imaging, in the corneal stroma after normal- and high-intensity collagen crosslinking in postmortem enucleated porcine eyes at controlled intraocular pressures (IOPs). METHODS: Reflection-mode SH optical imaging of the stroma was realized after standard collagen cross-linking (CXL) and accelerated crosslinking (AXL) of porcine corneas, and the results were compared with the results for untreated controls. Ultraviolet-X lamps (365 nm) were used during riboflavin crosslinking with intensities of 3, 10, 30, and 100 mW/cm2 for constant 5.4-J/cm2 exposure doses. The IOP was varied using saline solution injected through the optic nerve and monitored using a Schiotz tonometer. SH optical imaging was realized with an in-house build multiphoton microscope using an ultrafast dispersion-compensated Ti-sapphire laser. RESULTS: SH reflection images of CXL and AXL porcine corneas obtained at IOPs of 8, 11, 16, and 26 mm Hg showed a similar fibrillar structure of collagen lamellae. All crosslinked corneas showed an increased fibrillar contrast in comparison with untreated baseline images. At low IOPs, strong variations in the scattering were observed that reduced with an increase in the IOP, when fibrils tended to straighten out. At low and normal IOPs, no significant difference between CXL and AXL results could be observed. At very elevated IOPs, however, the impact of AXL was found to alter the fibrillar structure of the collagen becoming less apparent in SH images when compared with that of CXL. CONCLUSIONS: We found a strong influence of the IOP on SH reflection imaging of postmortem porcine corneal stroma. CXL and AXL led to similar SH images indicative of a similar tensile strength. Only at very elevated IOPs (26 mm Hg) did the results for AXL deviate from those of CXL, suggesting an IOP-related threshold for reliable applications of AXL.

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.