The electron density: a fidelity witness for quantum computation.

There is currently no combination of quantum hardware and algorithms that can provide an advantage over conventional calculations of molecules or materials. However, if or when such a point is reached, new strategies will be needed to verify predictions made using quantum devices. We propose that the electron density, obtained through experimental or computational means, can serve as a robust benchmark for validating the accuracy of quantum computation of chemistry. An initial exploration into topological features of electron densities, facilitated by quantum computation, is presented here as a proof of concept. Additionally, we examine the effects of constraining and symmetrizing measured one-particle reduced density matrices on noise-driven errors in the electron density distribution. We emphasize the potential benefits and future need for high-quality electron densities derived from diffraction experiments for validating classically intractable quantum computations of materials.

Review on Fatigue of Additive Manufactured Metallic Alloys: Microstructure, Performance, Enhancement, and Assessment Methods.

Additive manufacturing (AM), which is a process of building objects in a layer-upon-layer fashion from designed models, has received unprecedented attention from research and industry because it offers outstanding merits of flexibility, customization, reduced buy-to-fly ratio, and cost-effectiveness. However, the fatigue performance of safety-critical industrial components fabricated by AM is still far below that obtained from conventional methods. This review discusses the microstructural heterogeneities, randomly dispersed defects, poor surface quality, and complex residual stress generated during the AM process that can negatively impact the fatigue performance of as-printed parts. The difference in microstructural origin of fatigue failure between conventionally manufactured and printed metals is reviewed with particular attention to the effects of the trans-scale microstructures on AM fatigue failure mechanisms. Various methods for mitigating the fatigue issue, including pre-process, inter-process, and post-process treatments, are illustrated. Empirical, semi-empirical, and microstructure-sensitive models are presented to predict fatigue strength and lifetime. Summary and outlooks for future development of the fatigue performance of AM materials are provided.

Radiation Synthesis of Carbon/Aluminum/Silica Aerogel Nanoporous Structure Derived from Polyacrylamide Hydrogel for High Temperature and Oil Removal Applications.

Aerogel is a high-performance thermal resistance material desired for high-temperature applications like dye-sensitized solar cells, batteries, and fuel cells. To increase the energy efficiency of batteries, an aerogel is required to reduce the energy loss arising from the exothermal reaction. This paper synthesized a different composition of inorganic-organic hybrid material by growing the silica aerogel inside a polyacrylamide (PAAm) hydrogel. The hybrid PaaS/silica aerogel was synthesized using different irradiation doses of gamma rays (10-60 kGy) and different solid contents of PAAm (6.25, 9.37, 12.5, and 30 wt %). Here, PAAm is used as an aerogel formation template and carbon precursor after the carbonization process at a temperature of (150, 350, and 1100 °C). The hybrid PAAm/silica aerogel was converted into aluminum/silicate aerogels after soaking in a solution of AlCl3. Then, the carbonization process takes place at a temperature of (150, 350, and 1100 °C) for 2 h to provide C/Al/Si aerogels with a density of around 0.18-0.040 gm/cm3 and porosity of 84-95%. The hybrid C/Al/Si aerogels presented interconnected networks of porous structures with different pore sizes depending on the carbon and PAAm contents. The sample with a solid content of 30% PAAm in the C/Al/Si aerogel was composed of interconnected fibrils whose diameter was about 50 µm. The structure after carbonization at 350 and 1100 °C was a condensed opening porous 3D network structure. This sample gives the optimum thermal resistance and a very low thermal conductivity of 0.073 (w/m·k) at low carbon content (2.71% at temperature 1100 °C) and high vpore (95%) compared with carbon content 42.38% and vpore (93%) which give 0.102 (w/m·k). This is because at 1100 °C, the carbon atoms evolve to leave an area between Al/Si aerogel particles, increasing the pore size. Furthermore, the Al/Si aerogel had excellent removal ability for various oil samples.

Reference-State Error Mitigation: A Strategy for High Accuracy Quantum Computation of Chemistry.

Decoherence and gate errors severely limit the capabilities of state-of-the-art quantum computers. This work introduces a strategy for reference-state error mitigation (REM) of quantum chemistry that can be straightforwardly implemented on current and near-term devices. REM can be applied alongside existing mitigation procedures, while requiring minimal postprocessing and only one or no additional measurements. The approach is agnostic to the underlying quantum mechanical ansatz and is designed for the variational quantum eigensolver. Up to two orders-of-magnitude improvement in the computational accuracy of ground state energies of small molecules (H2, HeH+, and LiH) is demonstrated on superconducting quantum hardware. Simulations of noisy circuits with a depth exceeding 1000 two-qubit gates are used to demonstrate the scalability of the method.

Comparative study between effects of ginkgo biloba extract and extract loaded on gold nanoparticles on hepatotoxicity induced by potassium bromate.

In human organs, potassium bromate (KBrO3) produces toxicity. The main causes of KBrO3 hepatotoxicity are the formation of reactive oxygen species (ROS) and DNA damage. The purpose of this study is to show how ginkgo biloba extract (GBE) and extract loaded with nanogold particles (GBE@AuNPs) affect hepatotoxicity caused by KBrO3. The rats were separated into eight groups: control (group I), GBE (group II), AuNPs (group III), GBE@AuNPs (group IV), KBrO3 (group V), KBrO3 and GBE (group VI), KBrO3 and AuNPS (group VII), and KBrO3 and GBE@AuNPs (group VIII). KBrO3 generated DNA damage spots in a comet assay, which were associated with increased inflammatory indicators (IL-6), decreased anti-apoptotic Bcl-2, and increased apoptotic markers (Bax and caspase-3). The inflammatory, apoptotic, and ultrastructural alterations in liver tissue produced by KBrO3 were reduced in treated groups VI, VII, or VIII. The hepatotoxic effects of KBrO3 were reduced when GBE, AuNPs, or GBE@AuNPs were used; the particular GBE@AuNPs were the most effective.

Engineering Symmetry-Selective Couplings of a Superconducting Artificial Molecule to Microwave Waveguides.

Tailoring the decay rate of structured quantum emitters into their environment opens new avenues for nonlinear quantum optics, collective phenomena, and quantum communications. Here, we demonstrate a novel coupling scheme between an artificial molecule comprising two identical, strongly coupled transmon qubits and two microwave waveguides. In our scheme, the coupling is engineered so that transitions between states of the same (opposite) symmetry, with respect to the permutation operator, are predominantly coupled to one (the other) waveguide. The symmetry-based coupling selectivity, as quantified by the ratio of the coupling strengths, exceeds a factor of 30 for both waveguides in our device. In addition, we implement a Raman process activated by simultaneously driving both waveguides, and show that it can be used to coherently couple states of different symmetry in the single-excitation manifold of the molecule. Using that process, we implement frequency conversion across the waveguides, mediated by the molecule, with efficiency of about 95%. Finally, we show that this coupling arrangement makes it possible to straightforwardly generate spatially separated Bell states propagating across the waveguides. We envisage further applications to quantum thermodynamics, microwave photodetection, and photon-photon gates.

Patterns of Uveitis in Egypt.

Purpose: To investigate the clinical patterns of uveitis patients presenting to the uveitis clinic at Cairo University hospitals.Methods: A retrospective study was conducted on 313 cases of uveitis from May 2015 to May 2017. Patients had detailed ocular and medical examinations.Results: The most common anatomic form of uveitis was panuveitis (53.4%), followed by anterior uveitis (33.2%), posterior uveitis (12.8%) and intermediate uveitis (0.6%). A specific cause of uveitis was identified in 236 patients (75.4%). The most commonly identified causes were Behçet disease (29.1%), parasitic anterior chamber(AC) granulomatous uveitis (14.4%) and VKH (12.8%). Macular holes were found in 13 eyes, Behcet disease was the major contributor (12 eyes that represent 7.3% of eyes with Behcet disease).Conclusion: Panuveitis is the most common anatomic form of uveitis in Egypt and the etiologic diagnosis of uveitis should focus in particular on Behçet disease, parasitic AC granulomatous uveitis, and VKH.

Vector Analysis of Femtosecond Laser-Assisted Arcuate Keratotomy for Post-Keratoplasty Astigmatic Correction.

PURPOSE: To study the astigmatic correction of high post-keratoplasty astigmatism using Femtosecond laser (FSL)-assisted Arcuate Keratotomy (FS-AK). METHODS: A prospective interventional cohort study. We enrolled 17 eyes with high degree of irregular astigmatism, scheduled for FS-AK. FSL was used to perform paired arcuate incisions 1.00 mm inside the graft. Patients' uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and astigmatic change were recorded and followed up to 1 year after surgery. Vector analysis using Alpins' method was done to analyze the astigmatic correction. RESULTS: FS-AK reduced the refractive astigmatism at final follow-up visit at 12 months (p = 0.0008, repeated-measures analysis of variance [ANOVA]). The procedure improved the UCVA over the follow-up period (p = 0.007, repeated-measures ANOVA), with a similar effect on the BCVA (p = 0.046, repeated-measures ANOVA). There was a mild correlation between the target-induced astigmatism and the surgically induced astigmatism (R2 = 0.245) with a tendency to overcorrect more than under correct the astigmatism. A constant rotational error in the counterclockwise direction was also detected. CONCLUSIONS: FS-AK improves the visual outcome and reduces the refractive cylinder in post-penetrating keratoplasty astigmatism. The predictability of astigmatism correction was variable in reducing post-keratoplasty astigmatism. Refinement of the treatment nomogram for such cases is highly recommended.

Subfoveal choroidal thickness in diabetic macular edema.

Purpose: To evaluate subfoveal choroidal thickness (SFCT) in eyes with diabetic macular edema (DME) using spectral domain OCT (SD-OCT). Materials and methods: Ninety eyes were divided into three equal groups: group A, non-proliferative diabetic retinopathy (NPDR) with no DME; group B, NPDR having DME; and group C, non-diabetic patients. The central subfield retinal thickness (CSRT) and SFCT were measured using spectral domain OCT. Results: There was a moderate negative correlation between age and SFCT in group B (r=-0.455, P=0.012). We found no significant correlation between best corrected visual acuity (BCVA) and SFCT in all groups (for groups A, B, and C, respectively: r=0.189, P=0.316; r=-0.195, P=0.302; and r=-0.181, P=0.337). There was no significant correlation between duration of diabetes and SFCT (r=-0.118, P=0.534 and r=-0.136, P=0.475 for groups A and B, respectively). The CSRT was 229.13±16.2, 336.4±74.85, and 223.13±16.9 µm in groups A, B, and C, respectively. The mean SFCT was 260.6±49.2, 259±50.8, and 252±50 µm in groups A, B, and C, respectively. We found no significant correlation between CSRT and SFCT in all groups (for groups A, B, and C, respectively: r=-0.049, P=0.796, r=0.239, P=0.204, r=-0.021, P=0.914). There was no significant difference in SFCT between group B (DME) on one hand and groups A and C on the other hand (P=0.9 and 0.59, respectively). Conclusion: There is no significant correlation between CSRT and SFCT in DME. Choroidal thickness assessment is not an indicator of the severity of DME and cannot be used as a monitor of its progression.

Corneal Morphologic Characteristics in Patients With Down Syndrome.

Importance: Literature suggests corneal morphologic characteristics compatible with keratoconus are present in a high percentage of patients with Down syndrome (DS), suggesting the need to perform a detailed examination of the anterior segment to try to avoid serious visual impairment in this group of patients. Objective: To characterize the abnormal features of the cornea in patients with DS and compare these with a control group. Design, Setting, and Participants: Multicenter case-control study at Vissum Alicante, Alicante, Spain, and the Ophthalmology and Pediatric Department, Cairo University, Cairo, Egypt. Data collection took place between May 2013 and May 2016. Data were analyzed between June 2016 and August 2016. The study included 321 eyes of 217 participants from 2 groups: 112 participants in the DS group and 105 healthy participants in the control group. Interventions: Patients were evaluated using Placido disc/Scheimpflug camera topographer (Sirius, CSO). Visual, refractive and anterior, and posterior corneal characteristics were assessed and compared in both groups. Main Outcomes and Measures: Keratoconus diagnosis. Incidence of corneal morphologic irregularities similar to keratoconus in patients with DS. Results: In the DS group, mean (SD) age was 14.88 (15.76) years, 54 (48%) were women, 66 (59%) were white, and 46 (41%) were Arab. In the control group, mean (SD) age was 40.29 (14.66) years, 54 (51%) were women, and all were white. Clinical assessment of corneal topography showed that 71.3% (95% CI, 45.2-97.4) of patients in the DS group showed characteristics compatible with keratoconus. Differences were found in steepest keratometry of 47.35 diopters (D) in patients with DS vs 43.70 D in control individuals (difference, 3.65 D; 95% CI, 3.23-4.35 D; P <.001) and in corneal pachymetry of 503 µm in patients with DS vs 545 µm in control individuals (difference, 42 µm; 95% CI, 38.8-56.7 µm; P <.001). Conclusions and Relevance: Patients with DS have steeper and thinner corneas and more corneal aberrations than those without genetic alterations and normal corneas. The findings suggest a detailed corneal study should be considered in such patients to detect keratoconus and implement treatment as appropriate to try to avoid serious visual impairment in this group of patients.

Iris reconstruction using artificial iris prosthesis for management of aniridia.

PURPOSE: To discuss the limitations and benefits of the BrightOcular prosthetic artificial iris device in management of aniridia associated with aphakia or cataract. METHODS: This is a retrospective study including 5 eyes of 4 patients who underwent implantation of the BrightOcular iris prosthesis (Stellar Devices) for total or partial aniridia. The cases included 2 eyes of 1 patient with congenital aniridia associated with congenital cataract and 3 eyes with traumatic aniridia: 1 with subluxated cataractous lens and 2 with aphakia. In all cases, the iris prosthesis was implanted after a 3-piece acrylic intraocular lens was implanted. We evaluated the clinical course with a minimum follow-up period of 6 months, the intraoperative and postoperative complications, and the cosmetic satisfaction of patients. RESULTS: All patients had improved uncorrected distance visual acuity and best-corrected distance visual acuity. All patients had a transient corneal edema that resolved within the first postoperative week. Only the patient with congenital aniridia had a permanent increase in intraocular pressure and developed a band keratopathy throughout a 2-year follow-up period. The prosthesis was well-centered in all eyes except for one case that required scleral suture fixation after 3 months. All patients had a satisfactory cosmetic appearance. CONCLUSIONS: BrightOcular iris prosthesis is a safe and useful tool to correct aniridia associated with pseudophakia or aphakia. Being foldable, it is easy to be implanted through a small incision and placed in the ciliary sulcus without sutures when properly sized. Cosmetic results are satisfactory. Sizing methods should be improved.

Species identification and molecular typing of human Brucella isolates from Kuwait.

Brucellosis is a zoonotic disease of major concern in Kuwait and the Middle East. Human brucellosis can be caused by several Brucella species with varying degree of pathogenesis, and relapses are common after apparently successful therapy. The classical biochemical methods for identification of Brucella are time-consuming, cumbersome, and provide information limited to the species level only. In contrast, molecular methods are rapid and provide differentiation at intra-species level. In this study, four molecular methods [16S rRNA gene sequencing, real-time PCR, enterobacterial repetitive intergenic consensus (ERIC)-PCR and multilocus variable-number tandem-repeat analysis (MLVA)-8, MLVA-11 and MLVA-16 were evaluated for the identification and typing of 75 strains of Brucella isolated in Kuwait. 16S rRNA gene sequencing of all isolates showed 90-99% sequence identity with B. melitensis and real-time PCR with genus- and species- specific primers identified all isolates as B. melitensis. The results of ERIC-PCR suggested the existence of 75 ERIC genotypes of B. melitensis with a discriminatory index of 0.997. Cluster classification of these genotypes divided them into two clusters, A and B, diverging at ~25%. The maximum number of genotypes (n = 51) were found in cluster B5. MLVA-8 analysis identified all isolates as B. melitensis, and MLVA-8, MLVA-11 and MLVA-16 typing divided the isolates into 10, 32 and 71 MLVA types, respectively. Furthermore, the combined minimum spanning tree analysis demonstrated that, compared to MLVA types discovered all over the world, the Kuwaiti isolates were a distinct group of MLVA-11 and MLVA-16 types in the East Mediterranean Region.

XEN Glaucoma Implant with Mitomycin C 1-Year Follow-Up: Result and Complications.

Purpose. To evaluate gel microstent (XEN, Aquesys, Inc) for treatment of primary open angle glaucoma (POAG). Methods. In this prospective interventional study, 13 eyes with POAG underwent XEN implantation with subconjunctival mitomycin-C. Of those eyes, 3 were pseudophakic and 10 underwent simultaneous phacoemulsification and XEN. Patients had uncontrolled IOP, had intolerance to therapy, or had maximal therapy but undergoing cataract extraction. Follow-up visits included IOP, number of medications, vision, and complications and lasted for 1 year. Complete success was defined as IOP reduction ≥20% from preoperative baseline at 1 year without any glaucoma medications while partial success as IOP reduction of ≥20% at 1 year with medications. Results. IOP dropped from 16 ± 4 mmHg pre-op to 9 ± 5, 11 ± 6, 12 ± 5, 12 ± 4, and 12 ± 3 mmHg at 1 week, 1, 3, 6, and 12 months (p = 0.004, 0.026, 0.034, 0.01, and 0.01, Wilcoxon Signed Ranks) consecutively. BCVA (LogMAR) was 0.33 ± 0.34 and improved to 0.13 ± 0.11 at 1 year. Mean number of medications dropped from 1.9 ± 1 preoperatively to 0.3 ± 0.49 (p = 0.003) at 1 year. 42% of eyes achieved complete success and 66% qualified success. Complications included choroidal detachment in 2 eyes, and implant extrusion in 1 eye, and 2 eyes underwent trabeculectomy. Conclusion. XEN implant is an effective surgical treatment for POAG, with significant reduction in IOP and glaucoma medications at 1 year follow-up.

Epidemiological Features of Pediatric Ocular Trauma in Egypt.

Purpose. To review the epidemiology of serious pediatric ocular trauma presenting to Kasr El Aini Hospital, Cairo University. Methods. Children with serious ocular trauma during a six-month period were examined and their data was analyzed. Results. Eighty eyes of 75 patients were included in this study, with 64% males (P < 0.001) and average age of 5 years (5 months-15 years). There were 67 (83.75%) open globe injuries, 11 (13.75%) closed globe injuries, and 2 (2.5%) chemical injuries. Of the open globe injuries, 24 (30%) were ruptured globes and 43 (53.75%) were lacerations (31 penetrating injuries (38.75%), 6 IOFBs (7.5%), and 6 perforating injuries (7.5%)). Of the closed globe injuries, 3 had hyphema (3.75%), 5 had traumatic cataracts (6.25%), and 3 had vitreous hemorrhage with retinal detachment (3.75%). Forty-two patients (56%) presented within 24 hours, 28 patients (37.33%) presented between 24 hours and 1 week, and 5 patients (6.6%) presented after one week from the time of trauma. Seven eyes developed posttraumatic endophthalmitis (10% of open globe injuries). On leaving the hospital, 55 (68.75%) eyes had poor vision, 13 (16.25%) had moderate vision, and 12 (15%) had good vision. Conclusion. Children at a higher risk of trauma are males, >5 years, unsupervised, and involved in street activities. Immediate comprehensive primary management and secondary rehabilitation are mandatory in these cases.

Intraoperative Corneal Thickness Changes during Pulsed Accelerated Corneal Cross-Linking Using Isotonic Riboflavin with HPMC.

Purpose. To evaluate corneal thickness changes during pulsed accelerated corneal cross-linking (CXL) for keratoconus using a new isotonic riboflavin formula. Methods. In this prospective, interventional, clinical study patients with grades 1-2 keratoconus (Amsler-Krumeich classification) underwent pulsed accelerated (30 mW/cm(2)) CXL after application of an isotonic riboflavin solution (0.1%) with HPMC for 10 minutes. Central corneal thickness (CCT) measurements were taken using ultrasound pachymetry before and after epithelial removal, after riboflavin soaking, and immediately after completion of UVA treatment. Results. Twenty eyes of 11 patients (4 males, 7 females) were enrolled. Mean patient age was 26 ± 3 (range from 18 to 30 years). No intraoperative or postoperative complications were observed in any of the patients. Mean CCT was 507 ± 35 µm (range: 559-459 µm) before and 475 ± 40 µm (range: 535-420 µm) after epithelial removal (P < 0.001). After 10 minutes of riboflavin instillation, there was a statistically significant decrease of CCT by 6.2% from 475 ± 40 µm (range: 535-420 µm) to 446 ± 31 µm (range: 508-400) (P < 0.005). There was no other statistically significant change of CCT during UVA irradiation. Conclusions. A significant decrease of corneal thickness was demonstrated during the isotonic riboflavin with HPMC application while there was no significant change during the pulsed accelerated UVA irradiation.

Predicting postoperative visual outcomes in cataract patients with maculopathy.

PURPOSE: To assess the accuracy of the potential acuity meter (PAM) in predicting postcataract surgery visual acuity outcome in patients with healed inactive maculopathies. STUDY DESIGN: Prospective interventional clinical trial. PATIENTS AND METHODS: Patients scheduled for phacoemulsification had preoperative and 1 month postoperative best-corrected visual acuity (BCVA), PAM test, fluorescein angiography, and macular optical coherence tomography. Patients were grouped to following preoperative BCVA: PRE1: 0.29 and better, PRE2: 0.25-0.13, and PRE3: 0.1 or worse; age: G1 <60, G2 = 60-70, and G3 >70 years. PAM accuracy was divided into: Grade 1: Postoperative BCVA ≤1 or less line error of the PAM score, Grade 2: Between 1 and 2 lines error, and Grade 3: ≥3 lines or more error. RESULTS: This study enrolled 57 patients with a mean age of 71.05 ± 6.78 years where 34 were females. There were 21 (36.84%) patients with diabetic maculopathy and 36 (63.16%) with age-related macular degeneration. The mean preoperative BCVA was 0.198 ± 0.12 (0.1-0.5). The mean PAM score was 0.442 ± 0.24 (0.1-1.3). The mean postoperative BCVA was 0.4352 ± 0.19 (0.17-1.00). The PAM score was in Grade 1, 2, and 3 in 46 (80.7%), 54 (94.7%), and 56 (98.2), respectively. There was a highly significant correlation between the PAM score and the postoperative BCVA (P < 0.001, Chi-square test). There was no correlation between the PAM test accuracy and age, gender, diagnosis, and preoperative BCVA (P = 0.661, 0.667, 0. 0.991, 0.833, Chi-square test; respectively). CONCLUSION: The PAM is an accurate method of predicting postoperative visual acuity for eyes with nuclear cataracts Grade I and II and inactive maculopathies.

Work-related hand injuries treated at a tertiary care hospital.

BACKGROUND: The hands are known to be the most commonly injured body parts in traumatic occupational injuries. They can be disabling, leading to major adverse social and economic consequences for the worker and for his or her family. AIM: The aim of the study was to describe work-related hand injuries and their potential risk factors and also investigate lines of management in relation to the type of injury. PATIENTS AND METHODS: Patients who presented to the emergency room of a tertiary hospital over a 6-month period with occupational hand injuries were interviewed using a predesigned questionnaire. It included questions pertaining to the sociodemographic, occupational, and medical aspects related to the injury. RESULTS: A total of 163 patients were interviewed. More than 50% had injuries from cuts. Almost 60% of work-related hand injuries occurred in the absence of machines. The most common causes of hand injuries mentioned by workers were lack of concentration (68.7%), wearing no or ill-fitting gloves (63.2%), and a defect in the work place (51.5%). On examination, fingers were the most affected site (66.7%). About half of the cases were managed in the emergency room, 28.8% were managed with minor procedures, and 21.9% were managed with major procedures. CONCLUSION AND RECOMMENDATIONS: Work-related hand injuries have multifactorial causes; lack of concentration was the most common in this study. Injuries from cuts were the most common and fingers were the most affected part. Modifications of the possible risk factors may reduce the incidence of acute hand injury at work.

Delineating the extent of anterior capsulorhexis with gentian violet using capsulorhexis marker: a preliminary study of efficacy and toxicity in an animal model.

BACKGROUND: The purpose of this study was to evaluate the efficacy and safety of a new instrument to optimize the size, shape, and centration of anterior capsulorhexis. METHODS: The study was divided into two parts. The first part was done in 10 goats' eyes. A specially designed capsulorhexis marker was used. The lower edge of the instrument was stained by gentian violet and then applied to the anterior capsule to produce a circular mark of 5.5 mm. In five eyes, the gentian violet was applied to the marker using a corneal marking pen; in the remaining five eyes, the gentian violet was applied using a corneal marking pad. In the second part, the toxicity of gentian violet was tested as follows: ten albino rabbits received a gentian violet injection into the anterior chamber in one eye (experimental group) and an equal volume of balanced salt solution in the fellow eye (control group). Five rabbits were sacrificed one day after surgery and the remaining five rabbits after one week. RESULTS: In the first part, there was no difficulty in the introduction or removal of the instrument from all eyes. In the first two eyes, the circular mark was diffuse due to sliding of the marker on the surface of the anterior capsule. In the remaining eight eyes, there was a well-centered, rounded mark which was adequately stained. In the second part, there was no histopathological evidence of corneal toxicity in either group. There was loss of ganglion cells from the neurosensory retina one day after surgery in one eye from the experimental group. At one week, there was no evidence of retinal toxicity in any of the rabbits. CONCLUSION: This capsulorhexis marker can guide the surgeon to a better centration and proper sizing of anterior capsulorhexis using gentian violet staining. More refinement of the instrument is needed to be able to use it in human eyes.

Laser in situ keratomileusis to correct post-keratoplasty astigmatism; 1-step versus 2-step procedure.

PURPOSE: To investigate the correction of post-penetrating keratoplasty (PKP) astigmatism using laser in situ keratomileusis (LASIK). Visual and refractive outcomes were evaluated after LASIK was performed in 1 step (lamellar cut and ablation in 1 procedure) or 2 steps (lamellar cut then ablation in 2 successive procedures). SETTING: Department of Cornea and Refractive Surgery, Vissum-Instituto Oftalmológico de Alicante, University of Miguel Hernández, Alicante, Spain. METHODS: In this prospective observational study, 22 consecutive eyes were divided into 2 groups depending on the LASIK procedure performed to correct post-PKP astigmatism. Group 1 (1-step LASIK) included 11 eyes and Group 2 (2-step LASIK), 11 eyes. The patients were followed for 6 months. RESULTS: A statistically significant improvement was obtained in Group 2 with a mean vector analysis result of the cylinder of -4.37 diopters (D) +/- 1.79 (SD) (P = .018). In Group 1, the mean astigmatism correction was 2.38 +/- 1.71 D. The number of reoperations and residual refractive defects were significantly better in Group 2. CONCLUSION: The 2-step technique improved the accuracy of excimer laser correction of post-PKP astigmatism.