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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 Laser-assisted in situ keratomileusis (LASIK) lasers-patient labeling recommendations; draft guidance for industry and food and drug administration staff; availability.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.

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.

Arthur B Cummings, Stephanie Naughton, Ann-Marie Coen, Elizabeth Brennan, Gabrielle E Kelly The Wellington Eye Clinic, Dublin, D18 T8P3, IrelandCorrespondence: Arthur B CummingsThe Wellington Eye Clinic, Beacon Court, Level 2, Ste 36 Beacon Hall, Sandyford, Dublin, D18 T8P3, IrelandTel +353 1 2930470Fax +353 1 293 5978Email abc@wellingtoneyeclinic.comPurpose: 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.Keywords: comparative analysis, OCT, partial coherence interferometry biometers, cataract surgery, refractive outcomes

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.

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.

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.

Mazen M Sinjab,1,2 Roy S Rubinfeld,3,4 Kirsten Wagner,5,6 Edward C Parsons Jnr,7 Arthur B Cummings,8 Michael W Belin9 1Dr. Mazen Eye Clinic, Medcare Hospitals and Centres, Dubai, United Arab Emirates; 2Al Zahra Medical Group, Damascus, Syria; 3Department of Ophthalmology, Georgetown University Medical School/Washington Hospital Center, Washington, DC, USA; 4Re:Vision Private Practice, Rockville, MD, USA; 5Department of Ophthalmology, Medstar Georgetown University Hospital, Washington, DC, USA; 6Department of Ophthalmology, Medstar Washington Hospital Center, Washington, DC, USA; 7CXL Ophthalmics, Encinitas, CA, USA; 8Wellington Eye Clinic, Dublin, Ireland; 9Department of Ophthalmology, University of Arizona, Tucson, AZ, USACorrespondence: Roy S Rubinfeld 3131 Connecticut Ave, NW, #2809, Washington, DC, 20008, USAEmail Doctor@revisedeye.comPurpose: 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.Keywords: conductive keratoplasty, CK, corneal crosslinking, crosslinking, keratoconus, ectasia, thermokeratoplasty

Today it is widely accepted that corneal crosslinking stabilises the cornea in cases of keratoconus and kerectasia following corneal refractive surgery. Additionally, stopping eye rubbing is very important to achieve stability. But, CXL alone does not necessarily improve the visual acuity.

Corneal cross-linking (CXL) has been established as a successful treatment tool for the treatment of progressive keratoconus in terms of slowing or halting progressive corneal steepening and thinning and even on some occasions, reversing the steepening. To date the Dresden epithelium-off protocol is regarded as the gold standard and the epithelium-on (epi-on) approaches have met with less success. Both doctors and patients would welcome an epi-on CXL procedure that provided good outcomes as the morbidity with epi-on CXL is so much less and the safety is enhanced. Patient comfort is greater with the epi-on techniques when compared to epi-off. This study looked at 82 eyes that had documented progression of keratoconus and then underwent epi-on CXL using the CXLO system. The results show that corneal steepening can be halted and even reversed over a 2-year follow-up period with no complications noted. Over the 24 months post treatment on average there was a decrease in all keratometry values, BAD and ISV when compared to before treatment with IHD being marginally increased. Further studies over a longer follow-up period are required but recent publications using the same approach are validating the findings seen in this study.

When ablating the cornea with a myopic wavefront optimized (WFO) or aberration-free profile, the cornea is always going to receive more ablation in the centre than in the periphery of the optical zone and this will lead to the induction of spherical aberration. With manipulation of corneal asphericity, the final corneal asphericity can be influenced to preserve more natural prolateness than would otherwise occur. Asphericity-guided (Q-adjusted) procedures can also be used to induce corneal asphericity that enhances depth of field (hyper-prolate cornea). This is sometimes used in procedures called “Advanced monovision” due to the fact that the reading eye has better distance vision than would be the case in a patient with straight-forward monovision. Additional reasons for using an asphericity-guided ablation profile would be that for higher myopic corrections, the ablation depth is usually less than with a wavefront-optimised profile. Additionally, the refraction can be refined to 0.01D and the optical zone can be increased in 0.1 mm increments as opposed to 0.5 mm increments in WFO treatments. The target-Q can also be used to either attempt to preserve the preoperative Q-value (that is, not inducing any change) or a different Q-value could be targeted to create negative asphericity and increased depth of field for advanced monovision treatments.

Ablation profiles are generally derived from diagnostic data including the manifest refraction and then applied to calculations that generate the ablation profile and shot pattern. To date however, whether doing a wavefront optimized (WFO), wavefront-guided, asphericity-guided or topography-guided procedure, the calculations assume that the eye to be treated looks like the Gullstrand eye model. This has an axial length of 24 mm and a 43D corneal curvature while the eyes that undergo refractive surgery have a wide range of axial length and corneal curvature variations. With a ray tracing (RT) procedure, the Gullstrand eye model is replaced with the virtual eye model using the patient’s exact data for axial length, corneal radii and crystalline lens position. The ablation profile is obtained by ray-tracing this virtual model, generating an ablation profile and then doing a virtual procedure using this RT profile. Once the virtual procedure has been done, the virtual eye is examined again (using ray tracing) and if the light rays are all meeting on the macula, the profile is ready to be used. If the rays are not all converging on the macula, the aberrant rays are ray-traced backwards, and the necessary adjustments are made on the cornea. This is incorporated into the new RT profile and this iteration is repeated until all the light rays converge at the same point within the eye. Now the RT profile is ready to be used. Results show that RT outcomes perform all other profiles in all respects. More corneal tissue is used than with some other profiles however. The value of RT profiles is especially marked in those eyes that differ from the Gullstrand eye mode and they specifically benefit from the personal measurements. The RT profile is not commercially available at this juncture but will hopefully become available in the foreseeable future.

Topography-guided procedures were originally used only for complicated eyes and retreatments and are based on corneal data derived from either Placido disk topographers or Scheimpflug camera based tomographers. The refractive input is obtained from the manifest refraction, and the customised (or aberration element of the) treatment is derived from the corneal higher order aberrations (HOAs), like spherical aberration and coma. Initially, these procedures were performed in 2 stages, first the topography-guided procedure designed to regularise the cornea and reduce the corneal and hence ocular HOAs and secondly, a refinement procedure to correct the residual refractive error 6 months later. This last correction would typically be with the wavefront-optimised profile. Over time however it became possible to combine the HOA treatment with the low order aberration (LOA) treatment with relatively good refractive predictability, so most treatments performed nowadays are initiated as an intentional once-off procedure. If an enhancement treatment is required, it is certainly not regarded as a failure of the primary treatment, but the key issue is that it was planned as a one-step procedure rather than a two-step procedure. With the success achieved in the cases described above, topography-guided procedures were introduced to primary eye treatments i.e. patients having surgery for the first time and not necessarily patients with complaints. The results were fascinating in that primary topography-guided procedures provided better outcomes for these primary eyes than routine wavefront-optimised procedures for visual quality including night driving. Some of the reasons cited for this are that refinement of the corneal shape should be beneficial for visual quality by reducing HOAs, the refraction can be refined to 0.01 of a dioptre thereby increasing predictability, the tear film has normally been optimised to get good quality data scans, and the treatment is normally centred on the corneal apex rather than pupil centre.

Optical wavefront science is the photophysical description of optical perfection or imperfection. Understanding the principles of optical wavefront is essential for understanding its application, especially in customized laser vision correction (CLVC). The principal of wavefront measurement is the difference (deviation) between the actual wavefront shape of the measured surface and the ideal flat shape. This deviation is known as a wavefront aberration.

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. Financial Disclosure Dr. Cummings is a member of the medical advisory board of Wavelight, Erlangen, Germany, and a consultant to Alcon Laboratories, Inc., Fort Worth, Texas, USA. No author has a financial or proprietary interest in any material or method mentioned.

Corneal cross linking (CXL) has significant supporting evidence suggesting that it stabilizes keratoconus (KC) and increases corneal rigidity. Randomized clinical trials demonstrating this in a statistically significant manner would still be welcomed however.

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.]

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.

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 µ m) and the measured ablation depth at the thinnest corneal location (67.04 ± 30.94 µ m), the corneal apex (67.52 ± 31.22 µ m), or the pupil center (67.73 ± 31.48 µ m). Bland–Altman plots revealed moderate agreement for measurements at the thinnest point (95% limits of agreement [LoA]: −25.13 to 23.70 µ m), corneal apex (95% LoA: −24.70 to 22.33 µ m), and pupil center (95% LoA: −25.30 to 22.51 µ m), 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. [ J Refract Surg . 2016;32(3):164–170.]

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.

Video abstract Video, 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.

Purpose: To study the effects of oxygen administered to patients having cataract surgery under local anesthesia. Setting: The Pretoria Eye Institute, Arcadia, South Africa. Methods: In this prospective study, 31 patients were randomly divided into two groups; one received oxygen inhalation during surgery and the other, air. The saturation of oxygen in arterial blood, the partial pressure of oxygen in arterial blood (PaO2), the partial pressure of carbon dioxide in arterial blood (PaCO2), and the pH were evaluated in both groups. Results: The preoperative blood gas parameters were maintained in the air inhalation patients. Oxygen inhalation caused significant increases in the saturation of oxygen in arterial blood and in PaO2. There was no difference between the two groups in PaCO2. The pH of arterial blood showed a statistically significant decrease in the oxygen inhalation patients. This shift to more acidotic levels could cause central nervous system depression with reduced respiratory stimulus. Conclusions: We recommend that air rather than oxygen be administered to patients during cataract surgery.

Purpose To assess the efficacy, safety, and predictability of an individualized laser in situ keratomileusis (LASIK) ablation profile based on an optical ray-tracing algorithm to treat moderate to high myopic astigmatism. Setting Ophthalmology centers in Zurich, Switzerland; Dublin, Ireland; and, Cologne, Germany. Design Multicenter clinical trail. Methods This 3-center study enrolled eyes with a manifest refraction sphere ranging from 0.50 to −10.25 diopters (D) and/or astigmatism ranging from 0.00 to −4.50 D. The intended outcome was plano in most eyes, undercorrection of 0.50 D in 1 eye, and undercorrection of 0.25 D in 2 eyes. Refractive outcomes were analyzed preoperatively and postoperatively at 1 day and 1 and 3 months. Results The study enrolled 127 eyes (71 patients). The mean manifest refraction was −5.92 D ± 1.72 (SD). By 3 months postoperatively, 15 eyes had been lost to follow-up and 1 eye was excluded from analysis because of early retreatment. Of the remaining 111 eyes, 93 (83.8%) had an uncorrected distance visual acuity (UDVA) of 20/20 or better. The mean manifest refraction spherical equivalent (MRSE) in all eyes was 0.03 ± 0.30 D. In 97 (87.4%), the MRSE was within ±0.50 D and in 107 (96.4%), within ±1.00 D. No eye lost 2 or more lines of corrected distance visual acuity. Conclusions The new optical ray-tracing algorithm for individualized LASIK ablation profiles to treat moderate to high myopic astigmatism was efficacious, safe, and predictable. The UDVA in eyes with high myopic astigmatism was better than in those treated with wavefront-guided LASIK. Financial Disclosure Drs. Schumacher and Mrochen are paid scientific consultants to and Drs. Seiler and Cummings and Mr. Maus are members of the medical advisory board of Wavelight, Erlangen, Germany.

We describe new methodologies for the selection of the most appropriate power of intra-ocular lens (IOL) in cataract surgery, and how one might develop customized solutions for IOLs.