Comparison of a Scheimpflug imaging with other screening indices in diagnosing keratoconus and keratoconus suspect.

Keratoconus (KC) is an irreversible blinding eye disease; therefore, early screening of KC suspects (KCS) is crucial for protecting patients' quality of life. Scheimpflug imaging is a commonly used screening device in clinical practice. We aimed to evaluate the diagnostic ability of a Scheimpflug imaging device (Scansys) for KC and KCS and compared it with other Scheimpflug-based devices (Pentacam and Corvis ST). This prospective case-control study included 107 normal eyes, 72 KCS, and 57 KC. Scansys screening index Keratoconus probability (KCP) showed excellent performance in diagnosing KC at a cutoff value of 16.4 (area under the receiver operating characteristic [AUROC] = 1.000), with 100% sensitivity and 98.11% specificity. KCP had a better KCS diagnostic ability at a cutoff value of 8.9 (AUROC = 0.813) than Corvis biomechanical index (CBI, AUROC = 0.764), reaching 67.61% sensitivity and 85.85% specificity. Pentacam screening index Belin/Ambrósio enhanced ectasia display deviation (BAD-D) showed the best performance with 92.96% sensitivity and 89.62% specificity at a cutoff value of 1.525 (AUROC = 0.970) in diagnosing KCS. Scansys provides accurate KCP parameters in diagnosing KC; however, the efficiency of diagnosing KCS should be further optimized.

Associations between endothelial cell characteristics and corneal topography findings in different stages of keratoconus.

PURPOSE: This study aimed to compare and correlate specular microscope indices and corneal topography indices in different stages of keratoconus. METHODS: Two hundred forty-six eyes of 123 participants were enrolled in the study. Corneal topography was performed using Sirius (CSO, Italy), with a rotating Scheimpflug camera and a Placido disc topographer. Corneal endothelial cell indices were assessed using a specular microscope (Nidek CEM-530, Japan). Eyes were graded as keratoconus stages 0-4 according to the Amsler-Krumeich classification. Corneal topography and endothelial cell indices were compared among the groups, and the correlations between them were analyzed. RESULTS: The mean age of the patients was 23.26 ± 6.75 years (range, 14-47 years). Forty-eight cases were male (39%) and 75 were female (61%). There were no statistically significant age (p = 0.578) or sex ratio (p = 0.529) differences between the groups. Twenty-nine eyes were included in the control group (11.78%), while 41 (16.67%) had stage 1 keratoconus, 88 (35.77%) had stage 2, and 88 (35.77%) had stage 3. Measurement was not possible in stage 4 keratoconus. No statistically significant difference was determined in specular microscopy values according to the stage of keratoconus, except for the number of analyzed cells (NUM) (p > 0.05). The lowest NUM values were observed in stages 1, 2, and 3, with values of 184.34 ± 67.62 cells/mm2, 155.07 ± 59.48 cells/mm2, and 127.06 ± 64.39 cells/mm2, respectively (p = 0.001). In the keratoconus group, weak statistically significant negative correlations were observed between NUM and SimK1, SimK2, KVf, BCVf, KVb, and BCVb, while a weak positive correlation was noted between NUM and central corneal thickness (p < 0.05). CONCLUSIONS: NUM seems to decrease, while endothelial cell density exhibits no significant changes, with the progression of keratoconus. It appears that as keratoconus index values increase, NUM may decrease in different stages of keratoconus.

In Vivo Femtosecond Laser Machined Transepithelial Nonlinear Optical Corneal Crosslinking Compared to Ultraviolet Corneal Crosslinking.

Purpose: This study assessed the safety and efficacy of transepithelial crosslinking (CXL) using femtosecond (FS) laser-machined epithelial microchannels (MCs) followed by UVA CXL compared to FS laser (NLO CXL) in rabbits. Methods: The epithelium of 36 rabbits was machined to create 2- by 25-µm MCs at 400 MCs/mm2. Eyes were treated with 1% riboflavin (Rf) solution for 30 minutes, rinsed, and then crosslinked using UVA or NLO CXL. Rabbits were monitored by epithelial staining, optical coherence tomography (OCT) imaging, and esthesiometry. After sacrifice at 2, 4, or 8 weeks, corneas were examined for collagen autofluorescence and immunohistochemistry. Results: NLO CXL showed no epithelial damage compared to UVA CXL, which produced on average 23.89 ± 5.6 mm2 epithelial defects that healed by day 3. UVA CXL also produced loss of corneal sensitivity averaging 0.83 ± 0.24 cm force to elicit a blink response that persisted for 28 days and remained significantly lower than control or NLO CXL. OCT imaging detected the presence of a demarcation line only following UVA CXL but not NLO CXL. Conclusions: Even with improved transepithelial Rf penetration, UVA CXL resulted in severe epithelial damage, loss of corneal sensitivity, and delayed wound healing persisting for a month. When MCs were paired with NLO CXL, however, these issues were mostly negated. This suggests that MC NLO CXL can achieve a faster visual recovery without postoperative pain or risk of infection. Translational Relevance: UVA CXL is a successful procedure, but there is a need for a transepithelial protocol. The combination of MCs and NLO CXL is able to keep the benefits of UVA CXL without causing epithelial damage.

Is there a relationship between the keratoconus and the peripapillary choroidal vasculature?

PURPOSE: To evaluate the peripapillary/parapapillary choroidal vascular parameters in the keratoconus (KC) and to determine the relationship between topography parameters and the peripapillary/parapapillary choroidal vascular parameters. METHOD: Ninety eyes of ninety patients with different stages of KC and 29 eyes of twenty-nine patients without KC were enrolled in the study. Patients with KC were divided into three groups according to the Amsler-Krumeich classification scale. The choroidal vasculature was assessed by choroidal vascular parameters [such as parapapillary choroidal microvascular density (pCMVd) and peripapillary choroidal vascularity index (pCVI)]. These parameters were also evaluated for correlation with other parameters. RESULT: The retinal nerve fibre layer thickness (RNFLT) of the superior-temporal area and the pCVI were decreased in group 3 compared to the control group (superiror-temporal RNFLT: 122.27 ± 21.43 vs 139.90 ± 21.7, p = 0.01 and pCVI: 67.04 ± 4.14 vs 69.99 ± 4.38, p = 0.04). The superior-temporal RNFLT was decreased in group 3 compared to group 2 (122.27 ± 21.43 vs 141.83 ± 25.58, p = 0.006). There was a negative correlation between pCVI and average simulated keratometry (mean sim K), but this association was weak (r = - 0.29 p = 0.001). CONCLUSION: This study demonstrated that there may be changes in pCVI in patients with grade 3 KC and that there may be an association between pCVI and mean sim K. As KC grade increases, pCVI may decrease. Furthermore, pCVI may have a negative correlation with mean sim K.

Multi-dataset identification of innovative feature genes and molecular mechanisms in keratoconus.

This study aimed to identify feature genes and explore the molecular mechanisms of keratoconus (KC). We downloaded data files from NCBI GEO public database. The Limma package was used for differential expression analysis of gene profiles. Lasso regression was used to identify the feature genes. The CIBERSORT algorithm was used to infer the proportion of immune-infiltrating cells and analyse the correlation between gene expression levels and immune cells. Related transcription factors and miRNAs of key genes were predicted using the Cistrome DB and Mircode databases. Analysis of expression differences in disease genes was based on the GeneCards database. The CMap was used to analyse targeted therapeutic drugs. IHC was performed to verify the expression levels of ATOH7 and MYRF in corneas. Exactly 593 upregulated and 473 downregulated genes were identified. Lasso regression analysis identified ATOH7, DBNDD1, RNF217-AS1, ARL11, MYRF and SNORA74B as feature genes for KC. All key genes were correlated with immune infiltration and the levels of activated memory CD4+ T cells and plasma cells were significantly increased. miRNA, IRF and STAT families were correlated to feature genes. The expression levels of key genes were significantly correlated to KC-related genes. Entinostat, ochratoxin-a, diphencyprone and GSK-3-inhibitor-II were predicted as potential KC medications. The expression of MYRF was significantly higher in the KC samples, contrary to the expression of ATOH7. KC is related to both immune infiltration and genetic factors. MYRF and ATOH7 were newly identified and verified feature genes of KC.

Static magnetic field effects on the secondary structure and elasticity of collagen molecules; a possible biophysical approach to treat keratoconus.

Type I collagen is among the major extracellular proteins that play a significant role in the maintenance of the cornea's structural integrity and is essential in cell adhesion, differentiation, growth, and integrity. Here, we investigated the effect of 300 mT Static Magnetic Field (300 mT SMF) on the structure and molecular properties of acid-solubilized collagens (ASC) isolated from the rat tail tendon. The SMF effects at molecular and atomic levels were investigated by various biophysical approaches like Circular Dichroism Spectropolarimetery (CD), Fourier Transform Infrared Spectroscopy (FTIR), Zetasizer light Scattering, and Rheological assay. Exposure of isolated type I collagen to 300 mT SMF retained its triple helix. The elasticity of collagen molecules and the keratoconus (KCN) cornea treated with SMF decreased significantly after 5 min and slightly after 10, 15, and 20 min of treatments. The exposure to 300 mT SMF shifted the Amid I bond random coil to antiparallel wave number from 1647 to 1631 cm-1. The pH of the 300 mT SMF treated collagen solution increased by about 25 %. The treatment of the KCN corneas with 300 mT SMF decreased their elasticity significantly. The promising results of the effects of 300 mT SMF on the collagen molecules and KCN cornea propose a novel biophysical approach capable of manipulating the collagen's elasticity, surface charges, electrostatic interactions, cross binding, network formation and fine structure. Therefore, SMF treatment may be considered as a novel non-invasive, direct, non-chemical and fast therapeutic and manipulative means to treat KCN cornea where the deviated physico-chemical status of collagen molecules cause deformation.

Comparing the Postoperative Outcomes of Intrastromal Corneal Ring Segments in Three Different Topographic Patterns of Eccentric Keratoconus.

PURPOSE: To compare the postoperative outcomes following implantation of KERATACx ring segments (Imperial Medical Technologies Europe GmbH) in patients having eccentric keratoconus with three different topographic patterns. METHODS: This retrospective cohort study was conducted at Maadi Eye Subspeciality Center, Cairo, Egypt. The study included patients with keratoconus who had implantation of KERATACx ring segments. Three groups were segregated based on topographic keratoconus patterns using the Sirius CSO Topographer (CSO Italia): type I ectasia where the cone coincides with the corneal flat axis, type II ectasia in which the cone coincides with neither the steep nor the flat axis and lies between the two axes, and type II ectasia for cones coinciding with the corneal steep axis. The visual and topographic outcomes were compared preoperatively and postoperatively for the three enrolled groups. RESULTS: This study enrolled 92 eyes of 92 patients and had a mean ± standard deviation follow-up of 16.9 ± 9.2 months. The patients' medical records revealed that night vision complaints and halos around the light were experienced the most by the type III ectasia group (31.25%). For the type III ectasia group, four topographic indices and one visual parameter did not show statistically significant differences between the preoperative and postoperative data (inferior-superior difference at 2- and 4-mm diameter, coma aberration, higher order aberrations, and uncorrected distance visual acuity), contrary to the type I and II ectasia groups, which showed significant improvements in all evaluated parameters. CONCLUSIONS: The type III morphological pattern of ectasia is the least likely to benefit from KERATACx ring segments implantation. [J Refract Surg. 2024;40(9):e625-e634.].

Prospective Objective Analysis of Corneal Haze Following Customized Transepithelial PRK Without Mitomycin C Combined With Accelerated Corneal Cross-Linking Versus Corneal Cross-Linking Alone.

PURPOSE: To compare haze and refractive outcomes in patients undergoing combined accelerated corneal cross-linking (A-CXL) and selective wavefront-guided transepithelial photorefractive keratectomy (WG-transPRK) without mitomycin C (MMC) versus those undergoing A-CXL. METHODS: This prospective study analyzed 95 eyes (86 patients) with progressive keratoconus from October 2018 to October 2022. The first group underwent CXL combined with corneal or ocular WG-transPRK (CXL+PRK, n = 52), targeting higher order aberrations (HOAs). The second underwent CXL only (n = 43), both following the same accelerated CXL protocol without MMC on the SCHWIND Amaris laser platform (SCHWIND eye-tech-solutions). Baseline and postoperative evaluations (1, 3, 6, and 12 months) included uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, tomography, corneal HOAs, and optical coherence tomography (OCT) scans. A patented machine learning algorithm objectively detected and quantified stromal haze on OCT scans in grayscale units. RESULTS: In both groups, anterior corneal haze reflectivity and subepithelial haze peaked at 3 months postoperatively, then progressively decreased at 6 and 12 months. Haze did not differ between groups at any time point. By 12 months, CDVA increased by 2.5 lines in the CXL+PRK group (P < .001) and by 0.7 lines in the CXL group (P = .10), and maximum keratometry decreased from 51.70 ± 5.10 to 47.90 ± 7.90 diopters (D) (CXL+PRK group) (P < .001) and from 51.20 ± 5.10 to 50.30 ± 4.60 D (CXL group) (P = .004). Corneal HOAs decreased in both groups but more in the CXL+PRK group. CONCLUSIONS: Combining CXL with WG-transPRK without MMC does not result in increased haze when compared to A-CXL alone. This combined approach achieves greater improvements in visual, topographic, and aberrometric parameters. [J Refract Surg. 2024;40(9):e583-e594.].

Misclassification of Eyes With Progressive Keratoconus Using the KISA% Index.

PURPOSE: To determine the misclassification rate of the keratoconus percentage (KISA%) index efficacy in eyes with progressive keratoconus. METHODS: This was a retrospective case-control study of consecutive patients with confirmed progressive keratoconus and a contemporaneous normal control group with 1.00 diopters or greater regular astigmatism. Scheimpflug imaging (Pentacam HR) was obtained for all patients. KISA% index and inferior-superior (IS) values were obtained from the Pentacam topometric/keratoconus staging map. Receiver operating characteristic curves were generated to determine the area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity values. RESULTS: There were 160 eyes from 160 patients evaluated, including 80 eyes from 80 patients with progressive keratoconus and 80 eyes from 80 control patients. There were 20 eyes (25%) with progressive keratoconus misclassified by the KISA% index, with 16 eyes (20%) of the progressive keratoconus cohort classified as normal (ie, KISA% < 60). There were 4 eyes (5%) with progressive keratoconus that would classify as having "normal topography" using the published criteria for very asymmetric ectasia with normal topography of KISA% less than 60 and IS value less than 1.45. All controls had a KISA% index value of less than 15. The optimal cut-off value to distinguish cohorts was 15.31 (AUROC = 0.972, 93.75% sensitivity). KISA% index values of 60 and 100 achieved low sensitivity (80% and 73.75%, respectively). CONCLUSIONS: The KISA% index misclassified a significant proportion of eyes with progressive keratoconus as normal. Although highly specific for clinical keratoconus, the KISA% index lacks sensitivity, does not effectively discriminate between normal and abnormal topography, and thus should not be used in large data analysis or artificial intelligence-based modeling. [J Refract Surg. 2024;40(9):e614-e624.].

Causal Association Between Atopic Dermatitis and Keratoconus: A Mendelian Randomization Study.

Purpose: Although many studies have indicated that atopic dermatitis (AD) could contribute to the risk of keratoconus (KC), the causality between AD and KC remains controversial. This study aimed to explore the potential causal associations between AD and KC. Methods: Instrumental variables for both exposures and outcomes were obtained from large-scale genome-wide association study summary statistics from previous meta-analyses. Mendelian randomization (MR) was applied to infer causal associations between AD and KC. Our main analyses were conducted by inverse-variance weighted (IVW) method multiplicative random effect model, complemented with additional five models and sensitivity analyses. Reverse MR analysis was applied to determine the direction of the causal association between AD and KC. Results: Both IVW and weighted median methods revealed a causal effect of AD on KC (IVW odds ratio [OR], 1.475; P = 4.16 × 10-4; weighted median OR, 1.351; P = 7.65 × 10-3). The weighted mode, simple mode, and MR Egger methods demonstrated consistent direction of causality. Evidence from all sensitivity analyses further supported these associations. Reverse MR analyses did not suggest causal effects of KC on AD. Conclusions: This study supported a significant causal effect of AD on KC, and reverse MR analysis proved that the causal association was unilateral. Translational Relevance: This study provides valid evidence that regular ophthalmic examinations are recommended for patients with AD to detect and prevent KC at an early stage.

Exploring the Accuracy and Readability of ChatGPT in Providing Information to Patients With Keratoconus.

Patients with keratoconus may lack sufficient understanding of their illness. The authors assessed the accuracy and readability of ChatGPT (OpenAI) responses to common questions regarding keratoconus and found that the provided data are precise, with minor inaccuracies. The complexity of responses requires a high reading level, which may be unsuitable for many patients. [J Pediatr Ophthalmol Strabismus. 2024;61(5):e43-e46.].

Prediction model for treatment outcomes 3 years after corneal cross-linking for keratoconus.

PURPOSE: This study aimed to identify preoperative factors that predict visual acuity and Kmax 3 years after corneal cross-linking (CXL) in patients with keratoconus (KC), and to develop a prediction model. METHODS: We enrolled 68 patients with KC and followed up on 100 eyes that received CXL for at least 3 years. Preoperative data, including age, UDVA, CDVA, cylinder, SE, and the parameters of tomography including Kmax were collected as predictors. The primary outcomes were changes in CDVA (Delta CDVA) and Kmax (Delta Kmax) postoperatively. Univariate and multivariate linear regression were used to identify the correlation between the primary outcomes and predictors and establish prediction models. RESULTS: Both CDVA and Kmax remained stable from baseline to 3 years after CXL: from 0.25 ± 0.18 to 0.22 ± 0.20 (P = 0.308) and from 58.70 ± 9.52 D to 57.02 ± 8.83 D (P = 0.187), respectively. Multivariate analysis showed that worse preoperative CDVA (ß coefficient - 0.668, P < 0.001) and lower preoperative Kmean (ß coefficient 0.018,P < 0.001) were associated with greater improvement in CDVA after CXL. A smaller preoperative eccentricity (ß coefficient 8.896, P = 0.01) and a higher preoperative Kmean (ß coefficient - 1.264, P < 0.001) predicted a more flattening of postoperative Kmax. The prediction model for CDVA (R2 = 0.43) and Kmax (R2 = 0.37) could accurately estimate treatment outcomes. CONCLUSIONS: CXL is highly effective in halting or preventing further progression of KC. The preoperative factors CDVA and Kmean were able to predict visual acuity changes 3 years after CXL. And preoperative eccentricity and Kmean could predict Kmax changes 3 years after CXL.

A genetic investigation in five Chinese families with keratoconus.

Background: This study investigated the genetic characteristics of five Chinese families with keratoconus (KC). Methods: In the five families affected by KC, medical records, clinical observations, and blood samples were collected from all individuals. All KC family members (n = 20) underwent both whole exome sequencing of genomic DNA and Sanger sequencing to confirm the variants. Online software was utilized to analyze all variants, and the online server I-TASSER was employed for in silico predictions of the three-dimensional protein structures of the variants. The newly discovered variants and single nucleotide polymorphisms were further examined in 322 sporadic KC patients. Results: The Pentacam tomographic composite index in those affected first-degree family members of the probands showed a pathological change. Five new variants were detected in the five probands and other affected members in their families: a heterozygous missense variant g.19043832C>T (p.Ser145Asn) in the homer scaffolding protein 3 (HOMER3) gene; a heterozygous missense variant g.99452113G>A (p.Gly483Arg) in the insulin-like growth factor 1 receptor (IGF1R) gene; a heterozygous missense variant g.55118280G>T (p.Trp843Leu) in the echinoderm microtubule-associated protein like 6 (EML6) gene; a heterozygous frameshift variant c. 1226_1227del (p.Gln410Glufs*17) in the DOP1 leucine zipper-like protein B (DOP1B) gene; and a heterozygous splice-site variant c.7776+2T>A in the neurobeachin-like protein 2 (NBEAL2) gene. These variations were predicted to be potentially pathogenic and associated with KC. Conclusion: Five novel variants in HOMER3, IGF1R, EML6, DOP1B, and NBEAL2 genes were identified in this study and may be associated with the pathogenesis of KC. This study provides new information about the gene variants and their protein changes in KC patients. The findings should be explored further and could potentially be applied to the early diagnosis of KC before clinical onset.

Responsive porous microneedles with riboflavin ocular microinjection capability for facilitating corneal crosslinking.

Riboflavin-5-phosphate (riboflavin) is the most commonly used photosensitizer in corneal crosslinking (CXL); while its efficient delivery into the stroma through the corneal epithelial barrier is challenging. In this paper, we presented novel responsive porous microneedles with ocular microinjection capability to deliver riboflavin controllably inside the cornea to facilitate CXL. The microneedle patch was composed of Poly (N-isopropyl acrylamide) (PNIPAM), graphene oxide (GO), and riboflavin-loaded gelatin. After penetrating the cornea by the stiff and porous gelatin needle tip, the photothermal-responsive characteristic of the PNIPAM/GO hydrogel middle layer could realize the contraction of the gel under the stimulation of near-infrared light, which subsequently could control the release of riboflavin from the backing layer into the cornea stromal site both in vitro and in vivo. Based on the microneedles system, we have demonstrated that this microinjection technique exhibited superior riboflavin delivery capacity and treatment efficacy to the conventional epithelial-on protocol in a rabbit keratoconus model, with benefits including minimal invasiveness and precise administering. Thus, we believe the responsive porous microneedles with riboflavin ocular microinjection capability are promising for clinical corneal crosslinking without epithelial debridement.

Gene‒Environment Interaction Between CAST Gene and Eye-Rubbing in the Chinese Keratoconus Cohort Study: A Case-Only Study.

Purpose: Keratoconus (KC), characterized by progressive corneal protrusion and thinning, is a complex disease influenced by the combination of genetic and environmental factors. The purpose of this study was to explore potential gene‒environment interaction between the calpastatin (CAST) gene and eye-rubbing in KC. Methods: A case-only study including 930 patients (676 patients with eye-rubbing and 254 patients without eye-rubbing) from the Chinese Keratoconus (CKC) cohort study was performed in the present study. Genotyping of single nucleotide polymorphism (SNP) was conducted using the Illumina Infinium Human Asian Screening Array (ASA) Beadchip. The gene‒environment interactions between CAST gene and eye-rubbing were analyzed using PLINK version 1.90. The interactions between CAST genotypes and eye-rubbing were analyzed by logistic regression models. The SNP-SNP-environment interactions were analyzed using generalized multifactor dimensionality reduction (GMDR). Results: Three SNPs in CAST gene, namely, rs26515, rs27991, and rs9314177, reached the significance threshold for interactions (defined as P < 2.272 × 10-3). Notably, the minor alleles of these three SNPs exhibited negative interactions with eye-rubbing in KC. The results of logistic regression models revealed that the minor allele homozygotes and heterozygotes of rs26515, rs27991, and rs9314177 also exhibited negative interactions with eye-rubbing. Furthermore, GMDR analysis revealed the significant SNP-SNP-environment interactions among rs26515, rs27991, rs9314177, and eye-rubbing in KC. Conclusions: This study identified rs26515, rs27991, and rs9314177 in CAST gene existed gene-environment interactions with eye-rubbing in KC, which is highly important for understanding the underlying biological mechanisms of KC and guiding precision prevention and proper management.

Screening Preadolescents for Keratoconus Risk Factors in a Low-Resource Setting.

BACKGROUND: Diagnosis of keratoconus (KC) involves the identification of corneal signs, refraction, and corneal imaging. The prevalence of KC ranges between 0.4 per 100,000 and 4,790, depending on geographical location and ethnicity. Diagnosis of KC should occur early for appropriate management with relatively affordable, accessible options to prevent visual impairment in low-income settings. METHOD: Written consent and assent were obtained from subjects before a questionnaire was administered to collate demographics, general and ocular history of subjects, and keratoconus risk factors. A novel scoring system was applied to identify subjects at a higher risk of developing KC and document KC risk factors prevalent in Harare using an informed risk score calculation. RESULTS: Thousand one hundred fifty-three subjects aged between 6 and 12 years were seen. The prevalence of KC was found to be 626/100,000 in primary school children resident in Harare. Reduced visual acuity, vernal keratoconjunctivitis, itchy eyes, eye rubbing, and atopy are the most prevalent KC risk factors identified in this community. Informed risk score calculation proved valuable in the screening for KC. CONCLUSION: The prevalence of KC in primary school children in Harare is 626/100,000, which is relatively high. School-aged children stand to benefit from the early screening for KC based on evidence-based practices in the absence of advanced clinical instrumentation.

Central corneal thickness and topographic indices in Malaysian children with vernal keratoconjunctivitis.

INTRODUCTION: Vernal keratoconjunctivitis (VKC) is a chronic allergic disease characterised by intense ocular surface symptoms and corneal involvement. There is limited data about the corneal changes in children with VKC based on severity of the disease. We aimed to compare the central corneal thickness (CCT) and corneal topographic indices in Malaysian children with VKC, as well as among the varying grades of VKC severity. MATERIALS AND METHODS: This study is a comparative, crosssectional and hospital-based study. We recruited 83 children with VKC and 83 healthy children as controls. All children underwent complete ocular examinations, CCT measurement using an ultrasound pachymeter and corneal topography using a Placido disc corneal analyser. RESULTS: There was a statistically significant difference of means CCT and topographic indices in children with VKC compared to controls (p<0.05). The probability keratoconus reached 18% in children with VKC. The mean CCT was observed to be thinnest in the severe-to-very severe groups of VKC compared to the mild-to-moderate (p<0.05). The means simulated-K1 and -K2, apical keratometry, apical gradient curvature, superior-inferior index and keratoconus prediction index were significantly different in severe-tovery severe VKC compared to mild-to-moderate VKC and controls (p<0.05). However, there was no significant difference in mean cylinder value and percent probability keratoconus when comparing different groups of severity of VKC (p=0.912 and 0.070 respectively). CONCLUSION: Children with VKC have thinner CCT and topographic indices changes compared to healthy children. Similar pattern was observed between groups with VKC. Degree of astigmatism and probability of keratoconus were similar in mild-to-moderate and severe-to-very severe groups.

Implantation of asymmetrical corneal intrastromal rings: A case series.

This case series reports eight eyes with keratoconus treated with laser implantation of one or two segments of progressive thickness corneal intrastromal ring (PT-ICRS). In this case series, it was evident that the insertion of PT-ICRS induces more pronounced corneal flattening at the thickest point, causing a reduction in distortion (coma) and lower astigmatism, resulting in a remarkable improvement in vision. Compared to the implementation of traditional intrastromal rings, the PT-ICRS variant showed superior results despite the small sample size. However, the same degree of asymmetry enhancement was not observed in cases in which a 330° PT-ICRS was implanted, despite the improvement in visual results when replacing a 320° traditional ring with a 330° PT-ICRS. These conclusions are limited as this is a case series with few cases.

The KERATO Biomechanics Study 1: A Comparative Evaluation Using Brillouin Microscopy and Dynamic Scheimpflug Imaging.

PURPOSE: To assess the corneal biomechanical properties in normal individuals and patients with keratoconus using the Brillouin optical scanning system (Intelon Optics) (BOSS) and compare them with ultra-high-speed Scheimpflug imaging (Corvis ST; Oculus Optikgeräte GmbH). METHODS: Sixty eyes from 60 patients (30 normal and 30 keratoconus) were included in this prospective, single-center, comparative, non-interventional study. Corneal biomechanics were evaluated using the Corvis ST and the BOSS. With the BOSS, each corneal image was acquired three times, measuring 10 locations within an 8-mm diameter. Parameters extracted included mean, maximum, and minimum Brillouin shift. These 10 points were also grouped into superior, central, and inferior regions. BOSS repeatability was assessed using the coefficient of repeatability and coefficient of variation. Furthermore, normal individuals and patients with keratoconus were compared using the Corvis ST and BOSS. RESULTS: The BOSS exhibited good repeatability, with coefficient of repeatability ranging from 0.098 to 0.138 GHz for single points in normal individuals and 0.096 to 0.149 GHz for patients with keratoconus. Statistical analysis revealed significant differences between normal individuals and patients with keratoconus, indicating softer corneas in keratoconus, observed with both the Corvis ST and BOSS. Specifically, the BOSS showed significant differences in mean, inferior, and superior mean, maximum, and minimum Brillouin frequency shift (all P < .05), whereas the Corvis ST displayed highly significant differences in stiffness parameter at first applanation, stress strain index, deformation amplitude ratio, and inverse integrated radius (all P < .001). CONCLUSIONS: Corneal biomechanical measurements proved highly repeatable and effectively demonstrated significant differences between normal individuals and patients with keratoconus using both the BOSS and the Corvis ST. [J Refract Surg. 2024;40(8):e569-e578.].