Clinical comparison of manual and laser-cut corneal tunnel for intrastromal air injection in femtosecond laser-assisted deep anterior lamellar keratoplasty (DALK).

PURPOSE: The most crucial step in deep anterior lamellar keratoplasty (DALK) is to achieve a bare Descemet's membrane. We aimed to assess a new femtosecond laser software that allows for a precise intrastromal tunnel creation for big bubble (BB) air injection using a real-time microscope-integrated optical coherence tomography. MATERIALS AND METHODS: A retrospective review of 61 eyes of 61 patients with keratoconus. Before introducing the new software update, DALK was performed using a partial-assisted femtosecond laser (partial-thickness circular cut followed by a lamellar cut) with manual intrastromal tunnel creation (partial FS-DALK group). After the software update, the femtosecond laser created the intrastromal tunnel (full FS-DALK group). RESULTS: In the full FS-DALK group, the BB's formation was significantly higher (64.3% vs. 36.4%, p = 0.04), and surgery time was shorter (21.8 ± 5.1 vs. 25.6 ± 6.8 min, p = 0.025) than in the partial FS-DALK. Penetrating keratoplasty conversion rate (7.1% vs. 15.1%, p = 0.432) was similar between the groups. Both groups showed statistically significant improvement in uncorrected and corrected distance visual acuity, central corneal thickness, surface asymmetry, and regularity indices. Endothelial cell density loss at 12 and 18 months was lower in the full compared with the partial FS-DALK group (12 months:10.0% vs. 16; 18 months: 10.7 vs. 16.5%, p < 0.001 for both comparisons). CONCLUSIONS: Creating the intrastromal guiding tunnel using FS laser for air injection resulted in a higher rate of BB formation, reduced long-term endothelial cell loss, and operating room time.

Labial mucosal epithelium grafting in an ex vivo human donor cornea model.

The purpose of the study was to establish a simple ex vivo corneal re-epithelization model and study the labial mucosal epithelium grafting as a potential approach for ocular surface reconstruction. Four human donor corneal buttons were overstored in a corneal cold storage solution at 4 °C for 32-52 days. Four labial oral mucosa strips were dissected from four patients during fornix reconstruction after they signed informed consent. The substantia propria was trimmed off, and the resulting graft was sutured near the corneal limbus with running sutures (thus forming the tissue construct). Constructs were cultured under the standard conditions with the anterior corneal side outwards. After 3 weeks of culture, constructs were removed, washed, and fixed. Sections were stained with hematoxylin and eosin (HE), anti-keratins 4, 13, 19, and p63. Nuclei were counterstained with Hoechst. After the cultivation, all constructs were integral with the attached graft and non-loosened sutures. The native cells were absent in all donor corneas. Histological evaluation demonstrated that the labial mucosal grafts were attached to the Bowman's membrane (BM), and its cellular outgrowths were found to be transit from the graft to the BM over the anterior surface in all constructs. Cells expressed mucosal epithelial keratins 4, 13, and 19, and several were p63-positive in nuclei. In the study, a simple ex vivo corneal re-epithelization model was successfully established. The model was potent in studying the labial mucosal epithelium grafting as an option for autologous ocular surface reconstruction in patients with bilateral limbal stem cell deficiency.

Rare single nucleotide variants in COL5A1 promoter do not play a major role in keratoconus susceptibility associated with rs1536482.

BACKGROUND: Keratoconus is a chronic degenerative disorder of the cornea characterized by thinning and cone-shaped protrusions. Although genetic factors play a key role in keratoconus development, the etiology is still under investigation. The occurrence of single-nucleotide polymorphisms (SNPs) associated with keratoconus in Russian patients is poorly studied. The purpose of this study was to validate whether three reported keratoconus-associated SNPs (rs1536482 near the COL5A1 gene, rs2721051 near the FOXO1 gene, rs1324183 near the MPDZ gene) are also actual for a Russian cohort of patients. Additionally, we investigated the COL5A1 promoter sequence for single-nucleotide variants (SNVs) in a subgroup of keratoconus patients with at least one rs1536482 minor allele (rs1536482+) to assess the role of these SNVs in keratoconus susceptibility associated with rs1536482. METHODS: This case-control study included 150 keratoconus patients and two control groups (main and additional, 205 and 474 participants, respectively). We performed PCR targeting regions flanking SNVs and the COL5A1 promoter, followed by Sanger sequencing of amplicons. The additional control group was genotyped using an SNP array. RESULTS: The minor allele frequency was significantly different between the keratoconus and control cohorts (main and combined) for rs1536482, rs2721051, and rs1324183 (p-value < 0.05). The rare variants rs1043208782 and rs569248712 were found in the COL5A1 promoter in two out of 94 rs1536482+ keratoconus patients. CONCLUSION: rs1536482, rs2721051, and rs1324183 were associated with keratoconus in a Russian cohort. SNVs in the COL5A1 promoter do not play a major role in keratoconus susceptibility associated with rs1536482.

Refractive outcomes following cataract combined with lamellar keratoplasty: femtosecond-DSEK versus microkeratome-DSAEK.

PURPOSE: Prediction of postoperative refraction following posterior lamellar keratoplasty is crucial for choosing proper intraocular lens power in combined surgeries. Femtosecond laser-assisted Descemet stripping endothelial keratoplasty (FS-DSEK) creates thin, planar grafts while microkeratome-assisted Descemet's stripping automated endothelial keratoplasty (DSAEK) creates non-planar, concaved grafts. We evaluated whether this fundamental difference affects the refractive outcomes in cataract surgery combined with FS-DSEK compared to cataract surgery combined with microkeratome-assisted DSAEK. METHODS: A retrospective analysis of 28 patients who underwent FS-DSEK combined with phacoemulsification and intraocular lens (IOL) implantation (group A) compared to 26 patients who underwent microkeratome-assisted DSAEK combined with phacoemulsification and IOL implantation (group B). Pre- and 1-year postoperative best-corrected visual acuity (BCVA), keratometry values, corneal thickness, central-to-peripheral graft thickness ratio (C/P ratio), and target postoperative spherical equivalent (SE) versus actual postoperative SE were analyzed. RESULTS: Target postoperative SE and actual postoperative SE significantly shifted toward hyperopia in group B, but not in group A. Postoperative hyperopic shifts were 0.14 D and 1.13 D in groups A and B, respectively (P < 0.001). BCVA improved after surgery in both groups, with no significant difference between the groups. Postoperative C/P ratio differed significantly between the groups and was negatively correlated with postoperative hyperopic shift (r = - 0.616, P < 0.001). CONCLUSION: Refractive outcomes of cataract surgery combined with FS-DSEK are relatively neutral, whereas those of cataract surgery combined with microkeratome-assisted DSAEK cause significant hyperopic shift. Clinicians should select accordingly an appropriate intraocular lens power when performing these surgeries.

Comparative analysis of biomechanical parameters of the corneas following Descemet membrane endothelial keratoplasty and contralateral healthy corneas.

PURPOSE: To compare the biomechanical properties of the unilateral operated corneas in patients who had undergone Descemet membrane endothelial keratoplasty (DMEK) for pseudophakic bullous keratopathy (PBK) with those of the contralateral normal corneas. METHODS: This was a retrospective cohort study conducted at university hospitals (Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel, and S. Fyodorov Eye Microsurgery State Institution, Moscow, Russia). Forty eyes of 20 patients who underwent DMEK for unilateral PBK 3.5 to 36 months ago and with normal fellow eyes were included in the study. An ocular response analyzer was used to measure the corneal biomechanical properties in the operated and normal fellow eyes. The main outcome measures were corneal hysteresis (CH) and corneal resistance factor (CRF). RESULTS: The mean CH (8.4 ± 1.5 mmHg vs. 8.2 ± 1.5 mmHg, P = 0.707) and the mean CRF (8.7 ± 1.6 mmHg vs. 8.3 ± 1.6 mmHg, P = 0.419) values did not show any statistically significant difference between the operated and the normal fellow eyes. CONCLUSIONS: In our study, the corneas that underwent DMEK for PBK showed normal values for biomechanical parameters. These findings support the previous studies that have reported near complete visual, functional, and ultra-structural rehabilitation of the corneas following DMEK.

Cataracts.

An estimated 95 million people worldwide are affected by cataract. Cataract still remains the leading cause of blindness in middle-income and low-income countries. With the advancement of surgical technology and techniques, cataract surgery has evolved to small-incisional surgery with rapid visual recovery, good visual outcomes, and minimal complications in most patients. With the development of advanced technology in intraocular lenses, the combined treatment of cataract and astigmatism or presbyopia, or both, is possible. Paediatric cataracts have a different pathogenesis, surgical concerns, and postoperative clinical course from those of age-related cataracts, and the visual outcome is multifactorial and dependent on postoperative visual rehabilitation. New developments in cataract surgery will continue to improve the visual, anatomical, and patient-reported outcomes. Future work should focus on promoting the accessibility and quality of cataract surgery in developing countries.

Recent advances in small pupil cataract surgery.

PURPOSE OF REVIEW: To highlight the existing and emerging cataract surgery trends in patients with insufficient mydriasis. Discuss the latest pharmacological approaches for pre and intraoperative pupil dilatation. Present the variety of newest pupil expansion devices; critically review their advantages and possible limitations to be considered by the surgeon. RECENT FINDINGS: The intracameral use of various mydriatic combinations augmenting the preoperative mydriatic instillations is currently gaining popularity in cataract surgery. Two main options are available: bolus injection of pharmacological agent or its constant irrigation during the phacoemulsification procedure. The former is aimed to expand the pupil, whereas the latter is mostly preventing the pupil from constriction. Introduction of femtosecond-assisted cataract surgery, apart from some benefits was followed by a variety of adverse effects including prostaglandin release into the aqueous humor causing pupil constriction. Preoperative administration of nonsteroidal anti-inflammatory drugs at least 1 day prior to surgery significantly decreases the chance of pupil constriction after laser energy is applied to the eye. However, pupil expansion devices may be needed in up to 10% of cases. Following the success of the Malyugin ring (MicroSurgical Technology Inc., Redmond, Washington, USA) several manufacturers introduced pupil expansion devices of various designs. They are differing with materials, pupillary margin fixation mechanisms, and easiness of manipulations during implantation and removal. SUMMARY: Combination of proper use of pre and intraoperative pharmacological pupil dilatation protocols combined with pupil expander rings allow for well tolerated and effective cataract surgery in the vast majority of patients with insufficient mydriasis.

Diagnostic Algorithm for Surgical Management of Limbal Stem Cell Deficiency.

BACKGROUND: Limbal stem cell deficiency (LCSD) presents several challenges. Currently, there is no clearly defined systematic approach to LSCD diagnosis that may guide surgical tactics. METHODS: The medical records of 34 patients with LSCD were analyzed. Diagnostic modalities included standard (visometry, tonometry, visual field testing, slit-lamp biomicroscopy with corneal fluorescein staining, Schirmer test 1, ultrasonography) and advanced ophthalmic examination methods such as anterior segment optical coherence tomography, in vivo confocal microscopy, impression cytology, and enzyme-linked immunoassay. RESULTS: Standard ophthalmological examination was sufficient to establish the diagnosis of LSCD in 20 (58.8%) cases, whereas advanced evaluation was needed in 14 (41.2%) cases. Depending on the results, patients with unilateral LSCD were scheduled to undergo glueless simple limbal epithelial transplantation (G-SLET) or simultaneous G-SLET and lamellar keratoplasty. Patients with bilateral LSCD with normal or increased corneal thickness were enrolled in the paralimbal oral mucosa epithelium transplantation (pLOMET) clinical trial. CONCLUSIONS: Based on the diagnostic and surgical data analyzed, the key points in LSCD diagnosis were identified, helping to guide the surgeon in selecting the appropriate surgical procedure. Finally, we proposed a novel step-by-step diagnostic algorithm and original surgical guidelines for the treatment of patients with LSCD.

Ethnicity, Progressive Keratoconus, and Outcomes after Corneal Cross-Linking in Southern Israel.

PURPOSE: To assess clinical outcomes of corneal cross-linking (CXL) intervention in a population diagnosed with progressive keratoconus. METHODS: This single-center retrospective cohort study included consecutive patients who underwent standard CXL or accelerated CXL for progressive keratoconus at a major teaching hospital in southern Israel between January 2015 and December 2019. Patients' medical files were reviewed, and pre-operative and post-operative data regarding demographics and clinical and tomographic characteristics were extracted and analyzed. RESULTS: This study included 166 patients (representing 198 eyes), out of which 98 patients (123 eyes) were ethnically Bedouin, and 68 patients (75 eyes) were ethnically Jewish. Overall, 126 patients (144 eyes) had a follow-up of at least 12 months (16.84 ± 5.76). The mean patient age was 20.62 ± 7.1 years old. There were significant baseline differences between the two ethnic groups in best-corrected visual acuity (BCVA; p < 0.001), uncorrected visual acuity (UCVA; p < 0.001), mean keratometry (p = 0.028), and corneal thickness (p < 0.001). Significant changes in BCVA, UCVA, and pachymetry parameters within each group were found after 12 months. Negative binomial regression analysis showed a maximal keratometry below 55D (RR = 1.247, p < 0.001), and a standard CXL procedure (RR = 1.147, p = 0.041) are significantly related to the stability of KC after 12 months. However, the effect size of the origin of patients is negligible (RR = 1.047, p = 0.47). CONCLUSIONS: In this study, the Bedouin population suffered from more progressive keratoconus when compared to the Jewish population. CXL was significantly effective in improving BCVA and UCVA in both groups after 12 months of follow-up. The effect size of the origin of patients on the stability of KC was found to be negligible.

Analysis of Corneal Biomechanical Properties in Different Keratotopographic Patterns of Keratoconus.

Purpose: To analyze the frequency of main keratotopographic patterns at the 1st, 2nd, and 3rd stages of keratoconus and investigate corneal biomechanical properties across different patterns. Methods: The study comprised two stages. The first stage was computational-experimental, where we utilized COMSOL Multiphysics® software (COMSOL AB, Stockholm, Sweden) to mathematically model corneal mechanical behavior under intraocular pressure and pulsed air jet action in both normal and keratoconic conditions. The second stage was the clinical phase, during which we retrospectively analyzed the examination results of both healthy subjects and patients with keratoconus. In total, the study included 256 eyes (256 subjects). Among them, 174 eyes (174 healthy individuals) had normal corneas with different refractions, and 82 eyes (82 individuals) had stages 1, 2, and 3 of keratoconus based on Amsler-Krumeich classification. The keratotopographic characteristics of the participants were assessed using Sirius (Schwind, Germany) and Pentacam AXL (OCULUS Optikgeräte GmbH, Germany) keratotomographs, while the corneal biomechanical properties were studied using noncontact tonometry with the Corvis ST device (OCULUS Optikgeräte GmbH, Germany). The study focused on evaluating corneal stiffness index values in the central optical zone under various keratotopographic patterns. In addition, it compared the elastic coefficient values c1, c2, and c3 for the model of hyperelastic behavior of corneal material outside the keratoconus zone. Furthermore, the study examined the values of reduced stiffness zone characteristics, including the stiffness reduction factor ψmax, effective radius Rk, and the ratio of maximum and minimum strain intensity in keratoconus of different stages. Results: The mean age of the patients in the study was 30.16 ± 8.31 years, with 166 men and 90 women participating. The study revealed typical keratotopographic patterns in the examined keratoconus stages, as well as their occurrence frequency. In the 1st stage of keratoconus, the pattern of asymmetric astigmatism was noted more frequently (in 75% of cases). In the 2nd stage, the pattern with an ectasia zone in the lower cornea was observed in 80% of cases, and in the 3rd stage, a centrally located keratotopographic ectasia pattern was found in 42% of cases. Comparative analysis showed that the greatest decrease in stiffness parameter (SpA1) and stress-strain index occurred in the central pattern (by 64% and 46%, respectively), while the least decrease was observed in local corneal radius reduction in the lower cornea (by 42% and 33%, respectively). Conclusions: The decrease in strength properties in keratoconus occurs in a local area, the size and degree of which are determined by the disease stage. The indicated biomechanical parameters are consistent regardless of the shape and localization of keratotopographic patterns but are relevant to diagnostic specifications using the Corvis ST pneumotonometer, which assesses corneal properties in the apical zone.

International results with the Boston type I keratoprosthesis.

PURPOSE: To determine the indications and outcomes of Boston type 1 keratoprosthesis (Massachusetts Eye and Ear Infirmary, Boston, MA) surgery performed outside of North America and to compare them with those obtained in the United States by the surgeon who trained the international surgeons. DESIGN: Retrospective review of consecutive clinical case series. PARTICIPANTS: One hundred ninety-four patients (223 keratoprosthesis procedures performed in 205 eyes) who received Boston type 1 keratoprosthesis at 11 ophthalmology centers in Armenia, India, Indonesia, Nepal, Philippines, Russia, and Saudi Arabia between May 1, 2006, and July 1, 2011 (international series), and at the Jules Stein Eye Institute between May 1, 2004, and July 1, 2011 (University of California, Los Angeles [UCLA] series). METHODS: Data were collected for each procedure regarding the preoperative characteristics of each eye, the surgical procedure(s) performed, and the postoperative outcomes. Statistical analysis was performed to identify significant differences between the international and UCLA series in terms of retention and complications. MAIN OUTCOME MEASURES: Interval visual acuities, keratoprosthesis retention, and significant postoperative complications. RESULTS: In the international series, 113 Boston type I keratoprostheses were implanted in 107 eyes of 100 patients. The most common indication for surgery was corneal graft failure (n = 50; 44%) followed by chemical injury (n = 30; 27%). Although only 2% of eyes had a preoperative corrected distance visual acuity (CDVA) of 20/20 to 20/200, 70%, 68%, and 59% of eyes had a postoperative CDVA of 20/20 to 20/200 at 6 months, 1 year, and 2 years after surgery, respectively. Ninety-one of the 113 keratoprostheses implanted (80.5%) were retained at a mean follow-up of 14.2 months, for a retention failure rate of 22 per 134.6 eye-years (0.163/eye-year). The most common postoperative complications were retroprosthetic membrane formation (27%) and sterile corneal necrosis (18%). The only postoperative complication that was more common in the international series than in the UCLA series was infectious endophthalmitis, which developed in 9% of eyes. CONCLUSIONS: Boston keratoprosthesis is a viable means of managing repeat graft failure and ocular chemical injury outside of North America, with similar visual acuity outcomes, retention rates, and incidence rates of postoperative complications to those obtained by North American surgeons.

Removing residual cortical material during cataract surgery: Visco polishing and the grindstone effect as a new surgical technique.

PURPOSE: To describe a new technique for removing residual cortical material adjacent to posterior lens capsule during cataract surgery with the help of cohesive ophthalmic viscosurgical devices. METHODS: In this technique, if there are still cortical remnants and lens epithelial cells left after the routine irrigation-aspiration and polishing at the final steps of cataract surgery, the capsule is filled to about one-third with a highly viscous cohesive ophthalmic viscosurgical device. Rinsing is performed from the anterior chamber with the water jet directed tangentially to the ophthalmic viscosurgical device bolus and towards the posterior capsule, which creates a turbulence creating a "grindstone effect". The ophthalmic viscosurgical device bolus transforms into a ball and starts to rotate very quickly within the capsule, grinding away the cortical remnants. RESULTS: In the first series of 62 cases, there were no intra-operative or post-operative complications. At day 1 there was no corneal oedema and no hypertension of intraocular pressure. Visual outcomes were good with a mean best corrected distance visual acuity of -0.01 ± 0.11 logMAR. CONCLUSION: This technique appears to be effective and fast in removing persistent cortical remnants from the surface of the posterior capsule, while minimising risks such as capsule aspiration during irrigation/aspiration. There is limited pressure and mechanical force applied on the capsule; the anterior chamber and the corneal endothelium remain safe since the ophthalmic viscosurgical device stays inside the capsular bag to its high cohesiveness and molecular weight. More data on a larger cohort of patients is planned to confirm these results and evaluate long-term effects on posterior capsule opacification.

Effect of Descemet Membrane Endothelial Keratoplasty Graft Storage Time on Graft Elasticity.

PURPOSE: The purpose of this study was to evaluate the effect of Descemet membrane endothelial keratoplasty (DMEK) graft storage time on its elastic properties, measured using atomic force microscopy (AFM). METHODS: Twenty human corneas (from 10 donors), unsuitable for transplantation, were obtained from the eye bank (S. Fyodorov Eye Microsurgery State Institution, Moscow). Ten DMEK grafts were prepared and stored in the corneal storage medium, Optisol-GS at 4°C after preparation, and AFM analysis was performed within 12 hours after preparation (group A). Ten paired corneas from the respective donors were stored in Optisol-GS at 4°C for 1 week after preparation before AFM analysis (group B). Data were analyzed using the Hertz model for the evaluation of the Young modulus of elasticity. RESULTS: Force-distance curve analysis showed an increase in the Young modulus of elasticity in group B in comparison with that in group A, and the mean values were 10.4 ± 1.8 kPa and 6.77 ± 2.25 kPa, respectively (P < 0.001). There was no correlation between the Young modulus of elasticity and donor age (r = 0.110, P = 0.644), endothelial cell count (r = -0.145, P = 0.541), and procurement interval (r = 0.14, P = 0.755). CONCLUSIONS: A longer graft storage time in cold storage medium was found to significantly reduce the elasticity of the DMEK graft. Clinically, this could potentially influence the unfolding of the DMEK graft within the anterior chamber during surgery and the postoperative detachment rate.

Corectopia grading: A novel classification system.

OBJECTIVES: To present and validate the novel grading system for objective classification of corectopia. SUBJECTS AND METHODS: We evaluated 28 eyes of 28 patients with or without corectopia and validated the grading and classification system for corectopia according to three major criteria: (i) direction, (ii) extent, and (iii) alteration of mydriasis. Intraclass correlation coefficient (ICC) and inter-rater agreement between 7 inexperienced and 1 experienced ophthalmologist against a golden standard (GS) were calculated. RESULTS: The ICC for the 7 inexperienced ophthalmologists regarding the grading of direction and centration of the pupil was 0.83 (95% confidence interval (CI), 0.74 to 0.90; p < .001) and 0.57 (95% CI, 0.43 to 0.72; p < .001), respectively. The inter-rater agreement was the same or almost the same in cases of pupil decentration between the inexperienced, experienced ophthalmologists and the GS (k = 0.82; 95% CI, 0.64-1.00; p < .001). In assessing the direction of pupil displacement, the inter-rater agreement was almost perfect between the inexperienced (k = 0.93; 95% CI, 0.84-1.00; p < .001) and experienced (k = 0.92; 95% CI: 0.82-1.02; p < .001) ophthalmologists and the GS. CONCLUSION: The first detailed clinical classification is proposed for objective corectopia grading particularly relevant in documenting and assessing progressive disease. It was confirmed to be acceptable for clinical use by inexperienced and experienced ophthalmologists alike.

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

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

Ophthalmic Viscosurgical Devices (OVDs) in Challenging Cases: a Review.

Ophthalmic viscoelastic devices (OVDs) are currently used in cataract surgery and have significantly improved the safety and effectiveness of this surgical procedure. OVDs are classified according to the zero-shear viscosity and the cohesion-dispersion index in cohesive, dispersive, and viscoadaptives. OVDs create and maintain anterior chamber depth and visibility, protecting the corneal endothelium and other intraocular tissues during surgery. The selection of the most adequate OVD is especially relevant when performing cataract surgery in challenging cases, such as in hard, mature cataracts, flat anterior chamber, pseudoexfoliation syndrome, intraoperative floppy iris syndrome, or glaucoma surgery. In such cases, OVD is crucial for facilitating the surgical procedure and the associated minimal complication rate. The use of a combination of OVDs (soft-shell technique and modifications), the use of blue-colored OVDs, and the combination of sodium hyaluronate with lidocaine have also been described as useful tools in some of these challenging cases.

Corneal Cross-Linking as Treatment in Pediatric Keratoconus: Comparison of Two Protocols.

INTRODUCTION: Keratoconus is a progressive corneal disease commonly treated by collagen cross-linking (CXL). Accelerated protocols have recently become common. This study sought to compare the outcomes of accelerated and standard CXL in terms of visual acuity, keratometry, and tomographic parameters in pediatric population. METHODS: We retrospectively reviewed the files of pediatric patients who underwent standard and accelerated CXL for keratoconus in our hospital, between October 2014 and March 2018. Changes in uncorrected distance visual acuity (UCDVA), best corrected distance visual acuity (BCDVA), tomographic keratometry parameters (K max, K steep, K flat, K mean), and endothelial density count (EDC) were assessed before and at 6 and 12 months following treatment. The analysis included intergroup and intragroup comparisons. RESULTS: This study included 53 eyes (44 patients). Fourteen eyes were treated with standard CXL (S-CXL, 3 mW/cm2, 30 min), while 39 underwent accelerated CXL (A-CXL, 9 mW/cm2, 10 min). Intergroup comparison found insignificant differences between groups, with the exception of better results for UCDVA in the S-CXL group after 12 months (P = 0.03). In this study, there was no significant difference between the two protocols postoperatively in BCDVA, K max, K mean, pachymetry, or corneal astigmatism. CONCLUSION: A-CXL is as safe and effective as S-CXL for stabilizing progressive keratoconus in pediatric population. Larger-sample-size studies with a longer follow-up time are required. Considering the long-term results of 9 mW A-CXL and its safety and efficacy profile, it should be preferred to S-CXL for reducing treatment time and improving patients' comfort.

Comparison between three protocols of corneal collagen crosslinking in adults with progressive keratoconus: Standard versus accelerated CXL for keratoconus.

OBJECTIVE: The study aimed to compare eye outcomes between the standard and accelerated corneal cross-linking (CXL) protocols over a 1-year follow-up, and assess whether the accelerated protocols are non-inferior to the standard. METHODS: A retrospective cohort study including patients older than 18 years diagnosed with progressive keratoconus who underwent a CXL procedure. The primary outcome was defined as an increase of more than 1.5 diopter (D) in Kmax. The analysis included intra- and inter-group comparisons assessing differences in eye characteristics before and 12 months after the procedure. Furthermore, we assessed whether the accelerated procedures were non-inferior to the standard regarding Kmax change after 12 months. RESULTS: Eighty-four patients included in the study of which 23, 37 and 23 underwent the standard CXL (group I), 10-min. (group II) and the 3-min. (group III) accelerated procedures, respectively. Intra-group comparison before and after 12 months of mean Ksteep and anterior corneal astigmatism showed significant improvement only for group I (-0.3D decrease for both). Inter-group comparison showed better results after 12 months for group I (-0.9 ± 1.2) compared to group III (0.1 ± 0.8) in Ksteep, Kmean (-0.5+1. vs 0.1+0.7, respectively) and anterior astigmatism (-0.5 + 0.9 vs 0.3+1.1, respectively). We could not declare that the accelerated CXLs are non-inferior to the standard (p-value = 0.11 and 0.15). CONCLUSION: The standard CXL showed better results for keratometry and astigmatism in comparison with the accelerated. Therefore, the wide use of the accelerated CXL should be considered and reviewed for longer follow-up time and larger sample size in focus on the visual acuity parameters.

Cataract Surgery in Very Old Patients: A Case-Control Study.

Advancements in surgical techniques and increased life expectancy have made cataract surgery more common among very old patients. However, surgical outcomes seem impaired in patients older than 90 years, especially with ocular comorbidities. A retrospective case-control study of 53 eyes of 53 very old patients (mean 92.6 ± 3.0) and 140 eyes of 140 matched patients (mean 75.2 ± 7.6) was undertaken. Groups were matched in terms of gender and systemic and ocular comorbidities. In very old patients, higher phacoemulsification energy (cumulative dissipated energy [CDE], 25.0 ± 22.4 vs. 16.1 ± 10.7, p = 0.01) and rate of intraoperative floppy iris syndrome (IFIS, 9.4% vs. 1.4%, p = 0.02) were observed compared to controls. Uncorrected (UCVA) and best-corrected distance visual acuity (BCVA) gains were significantly poorer among the very old patients than among the control at postoperative day 30 (0.20 ± 0.70 vs. 0.56 ± 0.61 logMAR, p < 0.001 and 0.27 ± 0.64 vs. 0.55 ± 0.62 logMAR, p = 0.006, respectively). Even after including CDE and IFIS as covariates, age remained an independent factor for poor visual gain at 30 days (p < 0.001). Cataract surgery in very old patients may demand more experienced surgeons due to higher nuclear density and the rates of IFIS. Expectations in visual acuity gains should be aligned with the patient's age.

Keratoconus Diagnostic and Treatment Algorithms Based on Machine-Learning Methods.

The accurate diagnosis of keratoconus, especially in its early stages of development, allows one to utilise timely and proper treatment strategies for slowing the progression of the disease and provide visual rehabilitation. Various keratometry indices and classifications for quantifying the severity of keratoconus have been developed. Today, many of them involve the use of the latest methods of computer processing and data analysis. The main purpose of this work was to develop a machine-learning-based algorithm to precisely determine the stage of keratoconus, allowing optimal management of patients with this disease. A multicentre retrospective study was carried out to obtain a database of patients with keratoconus and to use machine-learning techniques such as principal component analysis and clustering. The created program allows for us to distinguish between a normal state; preclinical keratoconus; and stages 1, 2, 3 and 4 of the disease, with an accuracy in terms of the AUC of 0.95 to 1.00 based on keratotopographer readings, relative to the adapted Amsler-Krumeich algorithm. The predicted stage and additional diagnostic criteria were then used to create a standardised keratoconus management algorithm. We also developed a web-based interface for the algorithm, providing us the opportunity to use the software in a clinical environment.