Using adaptive optics to optimize the spherical aberration of eyes implanted with EDOF and enhanced monofocal intraocular lenses.

PURPOSE: To assess the effect of change in ocular spherical aberration (SA) with adaptive optics on visual acuity (VA) at different defocus after implantation of extended depth-of-focus (EDOF) and enhanced monofocal intraocular lenses (IOLs). SETTINGS: Narayana Nethralaya Eye Hospital, Bangalore, India. DESIGN: Prospective, longitudinal, observational. METHODS: 80 eyes (40 patients) that had cataract surgery were included in the study. 40 eyes were implanted with Eyhance EDOF IOLs and the remaining with Vivity EDOF IOLs. Baseline ocular aberrations were measured with a visual adaptive optics aberrometer, then the optimal SA was determined by increasing it in steps of -0.01 µm up to -0.1 µm until the maximum improvement in near distance VA was observed for a given eye. Then the defocus curve for each eye was measured after modifying the ocular SA by magnitude equal to optimal SA. RESULTS: Most of the eyes accepted a negative induced SA of -0.05 µm (Eyhance group: 67.6%; Vivity group, 45.2%). In the Eyhance group (dominant eyes), VA improved at -2 diopters (D) ( P < .02) only and degraded at 0 D, +0.5 D, and +1 D defocus ( P < .05). In the Vivity group, the VA remained unchanged at all defocus ( P > .05). In the Eyhance group (nondominant eyes), VA improved at -3.5 D defocus only and degraded at +1.5 D and +2 D defocus ( P < .05). In the Vivity group, VA improved at -2.5 D defocus ( P < .05) only. CONCLUSIONS: A negative induced SA of -0.05 µm in implanted eyes was optimal for a slight improvement in distance-corrected near and intermediate VA without any significant decrease in baseline distance-corrected VA.

Simultaneous Topography-guided Custom Ablation With Corneal Cross-linking for Keratoconus: 10-Year Prospective Outcomes.

PURPOSE: To assess 10-year visual and tomographic outcomes of topography-guided custom ablation (T-CAT) with corneal cross-linking (CXL) in eyes with keratoconus. METHODS: T-CAT with CXL was performed in 600 eyes (522 patients). Based on the T-CAT ablation plan, the theoretical maximum ablation depth was 50 µm after epithelium removal. After ablation, accelerated corneal cross-linking (CXL) was performed in the central 8-mm zone (9 mW/cm2 for 10 minutes in "epi-off" mode). The visual acuity and tomography were assessed. RESULTS: There was significant improvement in uncorrected (P = .001) and corrected (P = .001) distance visual acuity after the procedure. Keratometry, root mean square lower order aberrations and higher order aberrations, defocus, coma 90°, and spherical aberration reduced significantly after surgery at 10 years of follow-up (P < .005). All Pentacam (Oculus Optikgerate GmbH) tomographic variables showed significant changes indicating regularization after T-CAT (P < .005). Flattening of greater than 5.00 diopters in maximum keratometry was noted in 6 eyes (1%). Two of 600 eyes progressed postoperatively and required repeat CXL. CONCLUSIONS: T-CAT plus CXL is a safe and effective technique even in the long term for regularizing the anterior corneal surface with significant visual improvement and reduction in higher order corneal aberrations. [J Refract Surg. 2023;39(11):759-766.].

Patient-specific finite element analysis of human corneal lenticules: An experimental and numerical study.

The number of elective refractive surgeries is constantly increasing due to the drastic increase in myopia prevalence. Since corneal biomechanics are critical to human vision, accurate modeling is essential to improve surgical planning and optimize the results of laser vision correction. In this study, we present a numerical model of the anterior cornea of young patients who are candidates for laser vision correction. Model parameters were determined from uniaxial tests performed on lenticules of patients undergoing refractive surgery by means of lenticule extraction, using patient-specific models of the lenticules. The models also took into account the known orientation of collagen fibers in the tissue, which have an isotropic distribution in the corneal plane, while they are aligned along the corneal curvature and have a low dispersion outside the corneal plane. The model was able to reproduce the experimental data well with only three parameters. These parameters, determined using a realistic fiber distribution, yielded lower values than those reported in the literature. Accurate characterization and modeling of the cornea of young patients is essential to study better refractive surgery for the population undergoing these treatments, to develop in silico models that take corneal biomechanics into account when planning refractive surgery, and to provide a basis for improving visual outcomes in the rapidly growing population undergoing these treatments.

Efficacy of customized corneal crosslinking versus standard corneal crosslinking in patients with progressive keratoconus (C-CROSS study): study protocol for a randomized controlled trial.

BACKGROUND: Keratoconus is a degenerative disorder of the cornea leading to a protrusion and thinning with loss of visual acuity. The only treatment to halt the progression is corneal crosslinking (CXL), which uses riboflavin and UV-A light to stiffen the cornea. Recent ultra-structural examinations show that the disease is regional and does not affect the entire cornea. Treating only the affected zone with CXL could be as good as the standard CXL, that treats the entire cornea. METHODS: We set up a multicentre non-inferiority randomized controlled clinical trial comparing standard CXL (sCXL) and customized CXL (cCXL). Patients between 16 and 45 years old with progressive keratoconus were included. Progression is based on one or more of the following changes within 12 months: 1 dioptre (D) increase in keratometry (Kmax, K1, K2); or 10% decrease of corneal thickness; or 1 D increase in myopia or refractive astigmatism, requiring corneal crosslinking. DISCUSSION: The goal of this study is to evaluate whether the effectiveness of cCXL is non-inferior to sCXL in terms of flattening of the cornea and halting keratoconus progression. Treating only the affected zone could be beneficial for minimalizing the risk of damaging surrounding tissues and faster wound healing. Recent non-randomized studies suggest that a customized crosslinking protocol based on the tomography of the patient's cornea may stop the progression of keratoconus and result in flattening of the cornea. TRIAL REGISTRATION: This study was prospectively registered at ClinicalTrials.gov on August 31st, 2020, the identifier of the study is NCT04532788.

Tear biomarkers in dry eye disease: Progress in the last decade.

Dry eye disease (DED) is a commonly occurring, multifactorial disease characterized by reduced tear film stability and hyperosmolarity at the ocular surface, leading to discomfort and visual compromise. DED is driven by chronic inflammation and its pathogenesis involves multiple ocular surface structures such as the cornea, conjunctiva, lacrimal glands, and meibomian glands. The tear film secretion and its composition are regulated by the ocular surface in orchestration with the environment and bodily cues. Thus, any dysregulation in ocular surface homeostasis causes an increase in tear break-up time (TBUT), osmolarity changes, and reduction in tear film volume, all of which are indicators of DED. Tear film abnormalities are perpetuated by underlying inflammatory signaling and secretion of inflammatory factors, leading to the recruitment of immune cells and clinical pathology. Tear-soluble factors such as cytokines and chemokines are the best surrogate markers of disease severity and can also drive the altered profile of ocular surface cells contributing to the disease. Soluble factors can thus help in disease classification and planning treatment strategies. Our analysis suggests increased levels of cytokines namely interleukin-1ß (IL-1ß), IL-2, IL-4, IL-6, IL-9, IL-12, IL-17A, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α); chemokines (CCL2, CCL3, CCL4, CXCL8); MMP-9, FGF, VEGF-A; soluble receptors (sICAM-1, sTNFR1), neurotrophic factors (NGF, substance P, serotonin) and IL1RA and reduced levels of IL-7, IL-17F, CXCL1, CXCL10, EGF and lactoferrin in DED. Due to the non-invasive sample collection and ease of quantitively measuring soluble factors, tears are one of the best-studied biological samples to molecularly stratify DED patients and monitor their response to therapy. In this review, we evaluate and summarize the soluble factors profiles in DED patients from the studies conducted over the past decade and across various patient groups and etiologies. The use of biomarker testing in clinical settings will aid in the advancement of personalized medicine and represents the next step in managing DED.

Impact of crossplay between ocular aberrations and depth of focus in topo-guided laser-assisted in situ keratomileusis outcomes.

Purpose: To develop a nomogram in cases with mismatch between subjective and Topolyzer cylinder, and based on the magnitude of the mismatch, customize a treatment plan to attain good visual outcomes post-laser-assisted in situ keratomileusis (LASIK) surgery. Methods: The patients were evaluated preoperatively using corneal tomography with Pentacam. Five optimal corneal topography scans were obtained from the Topolyzer Vario were used for planning the LASIK treatment. For the nomogram purpose, the patients were divided into three categories based on the difference between the subjective cylinder and Topolyzer (corneal) cylinder. The first group (group 1) consisted of eyes of patients, where the difference was less than or equal to 0.4 D. The second group (group 2) consisted of eyes, where the difference was more than 0.4 D and the subjective cylinder was lesser than the Topolyzer cylinder. The third group (group 3) included eyes where the difference was more than 0.4 D but the subjective cylinder was greater than the Topolyzer cylinder. LASIK was performed with the WaveLight FS 200 femtosecond laser and WaveLight EX500 excimer laser. Assessment of astigmatism correction for the three groups was done using Aplins vector analysis. For comparison of proportions, Chi-square test was used. A P value less than 0.05 was considered statistically significant. Results: The UDVA was statistically significantly different when compared between groups 1 and 2 (P = 0.02). However, the corrected distance visual acuity (CDVA) was similar among all the three groups (P = 0.1). Group 3 showed an increase of residual cylinder by -0.25 D, which was significant at intermediate and near reading distances (P < 0.05). Group 3 showed significantly higher target-induced astigmatism (TIA) compared to groups 1 and 2 (P = 0.01). The mean surgically induced astigmatism (SIA) was the least in group 2, which was statistically significant (P < 0.01). Conclusion: The outcomes for distance vision using our nomogram postoperatively were excellent, but further refinement for improving the near vision outcomes is required.

New simulation software to predict postoperative corneal stiffness before laser vision correction.

PURPOSE: To develop a new virtual surgery simulation platform to predict postoperative corneal stiffness (Kc mean ) after laser vision correction (LVC) surgery. SETTING: Narayana Nethralaya Eye Hospital and Sankara Nethralaya, India; Humanitas Clinical and Research Center, Italy. DESIGN: Retrospective observational case series. METHODS: 529 eyes from 529 patients from 3 eye centers and 10 post-small-incision lenticule extraction (SMILE) ectasia eyes were included. The software (called AcuSimX) derived the anisotropic, fibril, and extracellular matrix biomechanical properties (using finite element calculation) of the cornea using the preoperative Corvis-ST, Pentacam measurement, and inverse finite element method assuming published healthy collagen fibril orientations. Then, the software-computed postoperative Kc mean was adjusted with an artificial intelligence (AI) model (Orange AI) for measurement uncertainties. A decision tree was developed to classify ectasia from normal eyes using the software-computed and preoperative parameters. RESULTS: In the training cohort (n = 371 eyes from 371 patients), the mean absolute error and intraclass correlation coefficient were 6.24 N/m and 0.84 (95% CI, 0.80-0.87), respectively. Similarly, in the test cohort (n = 158 eyes from 158 patients), these were 6.47 N/m and 0.84 (0.78-0.89), respectively. In the 10 ectasia eyes, the measured in vivo (74.01 [70.01-78.01]) and software-computed (74.1 [69.03-79.17]) Kc mean were not statistically different ( P = .96). Although no statistically significant differences in these values were observed between the stable and ectasia groups ( P ≥ .14), the decision tree classification had an area under the receiver operating characteristic curve of 1.0. CONCLUSIONS: The new software provided an easy-to-use virtual surgery simulation platform for post-LVC corneal stiffness prediction by clinicians and was assessed in post-SMILE ectasia eyes. Further assessments with ectasia after surgeries are required.

Phase retardation and corneal sublayer thickness repeatability using ultrahigh-resolution polarization-sensitive OCT.

PURPOSE: To assess phase retardation and corneal sublayer thickness repeatability using ultrahigh-resolution polarization-sensitive optical coherence tomography (PS-OCT). SETTING: Narayana Nethralaya Eye Hospital, Bangalore. DESIGN: Observational. METHODS: In this study, all eyes were imaged using a custom-built ultrahigh-resolution PS-OCT and high-resolution hybrid OCT (MS-39). The repeatability of phase retardation en face maps and corneal sublayer thickness profiles was evaluated. The reflectivity and phase retardation were calculated from the 2 orthogonal polarization channels to generate en face maps of phase retardation and corneal sublayer thicknesses. 3 consecutive measurements of all participants were acquired for each eye. For each measurement, the participant was asked to sit back and was realigned again. The repeatability was assessed using the intraclass correlation coefficient (ICC). RESULTS: The study included 20 healthy eyes of 20 participants. The phase retardation en face maps showed preferential arrangement of collagen fibrils with least retardation in the apex and maximum retardation in the periphery. The phase retardation showed excellent repeatability (ICC >0.95) in all zones. The Bowman layer and stromal layer thicknesses were measured with excellent repeatability (ICC >0.93 and >0.99, respectively). Significant differences ( P < .05) in stromal layer thickness were observed between MS-39 and PS-OCT. The repeatability of epithelial thickness measurements was better with PS-OCT than MS-39. CONCLUSIONS: The combinational assessment of corneal birefringence and sublayer thicknesses shows the advanced potential of ultrahigh-resolution PS-OCT in routine clinical practice over current OCT devices.

Universal architecture of corneal segmental tomography biomarkers for artificial intelligence-driven diagnosis of early keratoconus.

AIMS: To develop a comprehensive three-dimensional analyses of segmental tomography (placido and optical coherence tomography) using artificial intelligence (AI). METHODS: Preoperative imaging data (MS-39, CSO, Italy) of refractive surgery patients with stable outcomes and diagnosed with asymmetric or bilateral keratoconus (KC) were used. The curvature, wavefront aberrations and thickness distributions were analysed with Zernike polynomials (ZP) and a random forest (RF) AI model. For training and cross-validation, there were groups of healthy (n=527), very asymmetric ectasia (VAE; n=144) and KC (n=454). The VAE eyes were the fellow eyes of KC patients but no further manual segregation of these eyes into subclinical or forme-fruste was performed. RESULTS: The AI achieved an excellent area under the curve (0.994), accuracy (95.6%), recall (98.5%) and precision (92.7%) for the healthy eyes. For the KC eyes, the same were 0.997, 99.1%, 98.7% and 99.1%, respectively. For the VAE eyes, the same were 0.976, 95.5%, 71.5% and 91.2%, respectively. Interestingly, the AI reclassified 36 (subclinical) of the VAE eyes as healthy though these eyes were distinct from healthy eyes. Most of the remaining VAE (n=104; forme fruste) eyes retained their classification, and were distinct from both KC and healthy eyes. Further, the posterior surface features were not among the highest ranked variables by the AI model. CONCLUSIONS: A universal architecture of combining segmental tomography with ZP and AI was developed. It achieved an excellent classification of healthy and KC eyes. The AI efficiently classified the VAE eyes as 'subclinical' and 'forme-fruste'.

Multiple ciliary localization signals control INPP5E ciliary targeting.

Primary cilia are sensory membrane protrusions whose dysfunction causes ciliopathies. INPP5E is a ciliary phosphoinositide phosphatase mutated in ciliopathies like Joubert syndrome. INPP5E regulates numerous ciliary functions, but how it accumulates in cilia remains poorly understood. Herein, we show INPP5E ciliary targeting requires its folded catalytic domain and is controlled by four conserved ciliary localization signals (CLSs): LLxPIR motif (CLS1), W383 (CLS2), FDRxLYL motif (CLS3) and CaaX box (CLS4). We answer two long-standing questions in the field. First, partial CLS1-CLS4 redundancy explains why CLS4 is dispensable for ciliary targeting. Second, the essential need for CLS2 clarifies why CLS3-CLS4 are together insufficient for ciliary accumulation. Furthermore, we reveal that some Joubert syndrome mutations perturb INPP5E ciliary targeting, and clarify how each CLS works: (i) CLS4 recruits PDE6D, RPGR and ARL13B, (ii) CLS2-CLS3 regulate association to TULP3, ARL13B, and CEP164, and (iii) CLS1 and CLS4 cooperate in ATG16L1 binding. Altogether, we shed light on the mechanisms of INPP5E ciliary targeting, revealing a complexity without known parallels among ciliary cargoes.

Mapping of corneal birefringence in thin and asymmetric keratoconus corneas with ultrahigh-resolution polarization-sensitive OCT.

PURPOSE: To evaluate phase retardation (PR) across healthy eyes and eyes with thin corneas (<500 µm) and with asymmetric and bilateral keratoconus (KC). SETTING: Narayana Nethralaya Eye Hospital, Bangalore, India. DESIGN: Observational cross-sectional. METHODS: There were 4 eye groups: healthy eyes (Group 1; n = 10 eyes), eyes with thin corneas and no clinical disease (Group 2; n = 10 eyes), eyes with asymmetric KC (Group 3; n = 5 eyes), and eyes with clinical KC (Group 4; n = 15 eyes). All eyes were imaged with polarization-sensitive optical coherence tomography (PS-OCT), MS-39, and Corvis-ST. Using PS-OCT, PR was analyzed in annular regions. The anterior (A-E) and Bowman (E-B) wavefront aberrations, epithelial Zernike indices (EZI), total corneal thickness, Corvis biomechanical index (CBI), total biomechanical index (TBI), and Belin-Ambrósio overall deviation index (BAD-D) were analyzed. RESULTS: Only CBI, TBI, BAD-D, A-E and E-B aberrations, EZI, and total corneal thickness distributions of Groups 1 (n =10), 2 (n =10), and 3 (n =5) were similar ( P > .05) but not CCT ( P < .05). PR distributions clearly showed that the eyes in Groups 1, 2, and 3 had a normal corneal birefringence unlike Group 4 (n = 10) eyes ( P < .05). The PR map was similar to the preferred orientations of collagen fibers seen in X-ray diffraction ex vivo studies of corneal stroma. CONCLUSIONS: PR distributions may eliminate the uncertainty associated with the stromal status of thin and asymmetric KC corneas. Group 2 and 3 eyes appeared as healthy because of normal corneal birefringence at the time of imaging, but a longitudinal follow-up of these eyes with PS-OCT may assist in early detection of onset of disease.

Extensive study of radiation dose on human body at aviation altitude through Monte Carlo simulation.

The diverse near-Earth radiation environment due to cosmic rays and solar radiation has direct impact on human civilization. In the present and upcoming era of increasing air transfer, it is important to have precise idea of radiation dose effects on human body during air travel. Here, we calculate the radiation dose on the human body at the aviation altitude, also considering the shielding effect of the aircraft structure, using Monte Carlo simulation technique based on Geant4 toolkit. We consider proper 3D mathematical model of the atmosphere and geomagnetic field, updated profile of the incoming particle flux due to cosmic rays and appropriate physics processes. We use quasi-realistic computational phantoms to replicate the human body (male/female) for the effective dose calculation and develop a simplified mathematical model of the aircraft (taking Boeing 777-200LR as reference) for the shielding study. We simulate the radiation environment at the flying altitude (at 10 km and considering geomagnetic latitude in the range of 45-50°), as well as at various locations inside the fuselage of the aircraft. Then, we calculate the dose rates in the different organs for both male and female phantoms, based on latest recommendations of International Commission on Radio logical Protection. This calculation shows that the sex-averaged effective dose rate in human phantom is 5.46 µSv/h, whereas, if we calculate weighted sum of equivalent dose contributions separately in female and male body: total weighted sum of equivalent dose rate received by the female phantom is 5.72 µSv/h and that by the male phantom is 5.20 µSv/h. From the simulation, we also calculate the numerous cosmogenic radionuclides produced inside the phantoms through activation or spallation processes which may induce long-term biological effects.

Risk Assessment of Aerosol Generation During Vitreoretinal Surgery Using High Speed Imaging Amidst the COVID-19 Pandemic.

Purpose: The purpose of this study was to discuss the propensity of aerosol and droplet generation during vitreoretinal surgery using high speed imaging amidst the coronavirus disease 2019 (COVID-19) pandemic. Methods: In an experimental set up, various steps of vitreoretinal surgery were performed on enucleated goat eyes. The main outcome measures were visualization, quantification of size, and calculation of aerosol spread. Results: During intravitreal injection, insertion of cannulas, lensectomy, and vitrectomy with both 23 and 25-gauge instruments, with either valved or nonvalved cannulas, aerosols were not visualized which was confirmed on imaging. Although there was no aerosol generation during active fluid air exchange (FAE), there was bubbling and aerosol generation at the exit port of the handle during passive FAE. Under higher air pressure, with reused valved and fresh nonvalved cannulas, aerosol generation showed a trajectory 0.4 to 0.67 m with droplet size of 200 microns. Whereas removing cannulas or suturing under active air infusion (35 mm Hg and above) aerosols were noted. Conclusions: Based on the above experiments, we can formulate guidelines for safe vitrectomy during COVID-19. Some recommendations include the use of valved cannulas, avoiding passive FAE or to direct the exit port away from the surgeon and assistant, and to maintain the air pressure less than or equal to 30 mm Hg. Translational Relevance: In the setting of the COVID-19 pandemic, the risk from virus laden aerosols, as determined using an experimental setup, appears to be low for commonly performed vitreoretinal surgical procedures.

Simultaneous Topography-Guided PRK/CXL Versus Topography-Assisted PTK/CXL: 1-Year Prospective Outcomes in Keratoconic Eyes.

PURPOSE: To compare 1-year visual and tomographic outcomes of topography-guided photorefractive keratectomy (TGPRK) and topography-assisted phototherapeutic keratectomy (TPTK) with corneal cross-linking (CXL). METHODS: TGPRK and TPTK were performed in 72 eyes (68 patients) and 74 eyes (71 patients), respectively. Based on the TGPRK ablation plan, the eyes underwent TPTK where the theoretical minimum corneal thickness (MCT) after surgery was less than 400 µm. In the TGPRK group, the theoretical maximum ablation depth was 50 µm after epithelium removal. In TPTK, a decentered single-step PTK was performed only in the steepest anterior curvature zone and the stromal ablation depth was limited to 25 µm. After ablation, accelerated CXL was performed in the central 8-mm zone (9 mW/cm2 for 10 minutes in "epithelium-off" mode) in both TGPRK and TPTK. The visual acuity and tomography were assessed. RESULTS: Improvement in uncorrected (P = .73) and corrected (P = .66) distance visual acuity was similar between the two groups. However, TGPRK eyes had a greater decrease in keratometry, anterior defocus, and spherical aberration (P < .001) at the cost of greater ablation of tissue (P < .001). The median MCT decreased by 27 and 52.5 µm in the TPTK and TGPRK eyes, respectively. Both groups had similar decreases in anterior root mean square of lower (P = .10) and higher (P = .12) order aberrations. CONCLUSIONS: Both TGPRK and TPTK improved visual acuity in the keratoconic eyes at 1 year of follow-up. However, TPTK removed less volume of tissue. Further, it could be an alternative to TGPRK if the theoretical stromal ablation exceeds 50 µm in thin keratoconic corneas. [J Refract Surg. 2021;37(8):562-569.].

Artificial Intelligence Efficiently Identifies Regional Differences in the Progression of Tomographic Parameters of Keratoconic Corneas.

PURPOSE: To develop an artificial intelligence (AI) model to effectively assess local versus global progression of keratoconus using multiple tomographic parameters. METHODS: This was a retrospective review of medical records of patients diagnosed as having keratoconus. A total of 1,884 Pentacam (Oculus Optikgeräte GmbH) scans of 366 eyes (296 patients) were analyzed. Based on an increase in maximum anterior curvature (Kmax), the eyes were classified as actual "progression" and "no progression." The corresponding changes in other Pentacam parameters were incorporated to train and cross-validate (five-fold) the AI models. Three AI models were trained (an increase in Kmax by A = 0.75 diopters [D], B = 1.00 D, and C = 1.25 D). The area under the curve (AUC), sensitivity, specificity, and classification accuracy, along with other metrics, were evaluated. RESULTS: The AUC, sensitivity, specificity, and classification accuracy were 0.90, 85%, 82%, and 83%, respectively, for Model A; 0.91, 86%, 82%, and 88%, respectively, for Model B; and 0.93, 89%, 81%, and 91%, respectively, for Model C. All models also predicted that 60% to 62% of the actual progression eyes had concomitant progression-associated changes in the other Pentacam parameters (global progression). However, there was discordance between increase in Kmax and concomitant associated changes in the other parameters in 38.8% to 40% of the eyes (local progression). CONCLUSIONS: The AI models identified the eyes where the increase in Kmax and corresponding progression-associated changes in the other parameters were in agreement. These eyes may require corneal cross-linking earlier than the rest. [J Refract Surg. 2021;37(4):240-248.].

Propensity of aerosol and droplet creation during oculoplastic procedures: A risk assessment with high-speed imaging amidst COVID-19 pandemic.

PURPOSE: The study uses principles of liquid and gas mechanics to verify and quantify the generation of aerosols in oculoplastic procedures, namely surgery using a scalpel, electrosurgical device, and a mechanized drill. METHODS: Surgical techniques were performed ex vivo using the electrosurgical device, scalpel, and mechanized drill on the muscle and bone of commercially available chicken. The liquid and gas dynamics were observed using a high-speed high-resolution Photron SA5 camera (0.125 to 8 ms temporal resolution, 0.016 to 0.054 mm/pixel spatial resolution) and stroboscopic lighting (Veritas 120 E LED Constellation). The analysis was performed using in-house algorithms and ImageJ software. RESULTS: The use of a mechanized drill at 35000 rpm and a 3 mm fluted burr generated aerosol with particle size 50 to 550 microns with a spread of 1.8 m radius. Surgical smoke was generated by an electrosurgical device in both cutting and coagulation modes. Dispersion of the smoke could be controlled significantly by the use of suction, mean smoke spread ratio being 0.065 without suction and 0.002 with use of suction within 2 cm. CONCLUSION: The quantification of the aerosol generation will help surgeons take practical decisions in their surgical techniques in the pandemic era.

Repeatability of biometry measured by three devices and its impact on predicted intraocular lens power.

PURPOSE: To compare the repeatability of ocular biometry measured with the LENSTAR LS 900, IOLMaster 700, and Anterion and its impact on predicted intraocular lens (IOL) power. SETTING: Tertiary eye-care facility in South India. DESIGN: Prospective, observational, cross-sectional study. METHODS: Eyes diagnosed with cataract had 3 consecutive scans on each biometers. The repeatability was assessed using the within-subject standard deviation (Sw), test-retest repeatability, and coefficient of variation (CoV). The agreement was evaluated with the intraclass correlation (ICC). The IOL power was calculated with the Barrett Universal II formula. RESULTS: The study comprised 127 eyes of 76 patients. The repeatability of all parameters for a given device were excellent (ICC >0.9, low CoV and Sw). The agreement of the parameters between the biometers was very good (range from 0.93 to 0.99). The predicted IOL power differed statistically between the devices (P < .05), but the difference was clinically insignificant between the 3 biometers (ICC >0.99 for repeat calculation of IOL power). CONCLUSIONS: All the biometers included in the study had good to excellent repeatability of biometry parameters. The agreement of the predicted IOL power was excellent between the 3 optical biometers.

Intracorneal Ring Segments Followed by Simultaneous Topography-Guided Removal of Epithelium and Stroma With Accelerated Collagen Cross-Linking For Keratoconus (I-TRESK/CXL).

PURPOSE: The aim of this study was to assess the visual, topographic, and aberrometric outcomes of a novel tissue sparing technique, topography-guided removal of epithelium, and stroma in keratoconus (TRESK) along with accelerated collagen cross-linking (CXL), 1 month after Intacs insertion. DESIGN: Prospective interventional study. METHODS: Fourty-eight eyes (45 patients) with keratoconus underwent femto-assisted Intacs insertion. After 1 month, TRESK and CXL (9 mW/cm2 for 10 minutes) was done. TRESK is a decentered trans-PTK (phototherapeutic keratectomy) with center and area of ablation at the location of the steepest tangential anterior curvature and area of the cone respectively. Total ablation (epithelium plus stroma) was limited to 75 µm. Postoperative measurements were performed 1 month after Intacs, 6 weeks after Intacs followed by TRESK/CXL, and at the final visit 12 months after Intacs followed by TRESK/CXL. RESULTS: For all eyes studied, uncorrected distance visual acuity and corrected distance visual acuity (CDVA) (logMAR) improved from preoperative means of 1.05 ±â€Š0.05 and 0.31 ±â€Š0.03 logMAR to postoperative means of 0.52 ±â€Š0.05 (P < 0.001) and 0.20 ±â€Š0.02 logMAR (P = 0.009), respectively. The mean preoperative sphere, cylinder and mean refractive spherical equivalent decreased from -4.52 ±â€Š0.98 D, -4.81 ±â€Š0.25 D, -6.93 ±â€Š0.99 D to -0.77 ±â€Š0.53 D (P = 0.029), -3.13 ±â€Š0.24 D (P = 0.002), and -2.34 ±â€Š0.53 D (P = 0.021), respectively with a mean keratometric flattening of 5.06D (P < .0001) at the final visit. In total, 2.08% of the eyes lost 1 Snellen line of CDVA. Sixty eight percent and 27% of the eyes gained 2 Snellen lines or more of uncorrected distance visual acuity and CDVA, respectively. CONCLUSIONS: Simultaneous TRESK with CXL done 1 month after Intacs insertion (I-TRESK) in keratoconus eyes provided significant visual gain with refractive and topographic improvement. This novel procedure involving customized PTK before CXL is safe, easy to plan and perform, and provides good outcomes.

In-vivo efficacy of biodegradable ultrahigh ductility Mg-Li-Zn alloy tracheal stents for pediatric airway obstruction.

Pediatric laryngotracheal stenosis is a complex congenital or acquired airway injury that may manifest into a potentially life-threatening airway emergency condition. Depending on the severity of obstruction, treatment often requires a combination of endoscopic techniques, open surgical repair, intraluminal stenting, or tracheostomy. A balloon expandable biodegradable airway stent maintaining patency while safely degrading over time may address the complications and morbidity issues of existing treatments providing a less invasive and more effective management technique. Previous studies have focused on implementation of degradable polymeric scaffolds associated with potentially life-threatening pitfalls. The feasibility of an ultra-high ductility magnesium-alloy based biodegradable airway stents was demonstrated for the first time. The stents were highly corrosion resistant under in vitro flow environments, while safely degrading in vivo without affecting growth of the rabbit airway. The metallic matrix and degradation products were well tolerated by the airway tissue without exhibiting any noticeable local or systemic toxicity.