Ocular dimensions of the Chinese adolescents with keratoconus

Prevalence and associated factors of myopia among adolescents aged 12-15 in Shandong Province, China: a cross-sectional study

Myopia is a growing concern worldwide, especially among adolescents. This study aimed to investigate the prevalence and associated factors of myopia in adolescents aged 12-15 in Shandong Province, China. This cross-sectional study adhered to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines and involved stratified random cluster sampling of 128,678 students from 186 middle schools across 17 cities in Shandong Province. Data collection was conducted from March to April 2024. We excluded students with organic eye diseases, abnormal binocular vision functions, or a history of eye injuries or surgeries. Myopia was assessed using the standard logarithmic visual acuity chart and autorefractor without inducing ciliary muscle paralysis. A comprehensive questionnaire survey was conducted to gather demographic characteristics and daily life behaviors. With the chi-squared test for univariable analysis and multivariable logistic regression for identifying significant factors. This study included 126,375 participants, with a gender distribution of 51.02% male and 48.98% female. The overall prevalence of myopia was 71.34%. Higher prevalence was observed in girls (72.26%) compared to boys (70.45%), and the prevalence increased with age, peaking at 73.12% in 15-year-olds. Urban residents had a higher prevalence (71.86%) than rural (70.39%). Factors such as increased frequency of eye usage while lying down or leaning forward, frequent use of eyes while walking or riding in a car, prolonged screen time, and extended homework duration were associated with higher odds of developing myopia. Conversely, higher frequency of outdoor exercise, maintaining proper posture during reading and writing, greater distance from eyes to screen, and longer sleep duration were associated with lower odds. Additionally, female gender, older age, urban residence, and parental history of myopia increased the risk. The high prevalence of myopia among adolescents in Shandong Province was influenced by a combination of demographic, behavioral, and environmental factors. The study highlighted the importance of lifestyle modifications, such as increasing outdoor activities and maintaining proper visual habits, limiting the duration of screen exposure and homework sessions, and extending sleep duration, to mitigate the risk of developing myopia. These findings underscored the need for targeted public health interventions and educational campaigns to address this significant public health issue.

Ocular Biometry Features and Their Relationship with Anterior and Posterior Segment Lengths among a Myopia Population in Northern China

Objectives: The study aims to explore the ocular biometry of a myopic population in Northern China, focusing specifically on anterior and posterior segment lengths. Methods: This is a cross-sectional study. The medical records of 3458 myopic patients who underwent refractive surgery were evaluated. Axial length (AL), anterior chamber depth (ACD), lens thickness (LT) and other biometric parameters were measured using the IOL Master 700. The study determined the anterior segment length (ASL = ACD + LT), the posterior segment length (PSL = AL - ASL) and the ratio of ASL to PSL (ASL/PSL). Results: This study included 3458 eyes from 3458 myopic patients (1171 men and 2287 women). The mean age was 27.38 ± 6.88, ranging from 16 to 48 years old. The mean ASL was 7.35 ± 0.27 mm, and the mean PSL was 18.39 ± 1.18 mm. The ASL and PSL trends demonstrate an age-related increase for both genders, with notable gender-specific variations. Across most age groups, males typically exhibited higher ASLs and PSLs than females, with the exception of the 35-40 and 40-45 age groups. The ASL and PSL consistently increased with a rising AL. The AL strongly correlates with the PSL and negatively correlates with the ASL/PSL ratio. The ACD and LT moderately correlate with the ASL, but an increased LT does not imply a longer posterior segment. The CCT and SE show little correlation with axial eye parameters. Conclusions: Among Chinese myopic patients, a longer ASL and PSL were correlated with older age and the male gender. The AL strongly correlates positively with the PSL and negatively correlates with the ASL/PSL ratio. An elongation of the posterior segment may primarily account for an eyeball's lengthening.

New dawn for keratoconus treatment: potential strategies for corneal stromal regeneration

Keratoconus is a progressive, ectatic and blinding disorder of the cornea, characterized by thinning of corneal stroma. As a highly prevalent among adolescents, keratoconus has been a leading indication for corneal transplantation worldwide. However, the severe shortage of donor corneas is a global issue, and the traditional corneal transplantation surgeries may superinduce multiple complications, necessitating efforts to develop more effective strategies for keratoconus treatment. In this review, we summarized several strategies to promote corneal stromal regeneration or improve corneal stromal thickness, including cell-based therapies, biosynthetic alternatives for inducing corneal regeneration, minimally invasive intrastromal implantation and bioengineered tissues for implantation. These strategies provided more accessible but safer alternatives from various perspectives for keratoconus treatment, paving the way for arresting the keratoconus progression in its earlier stage. For the treatments of corneal ectatic diseases beyond keratoconus, these approaches will provide important references and widen the therapy options in a donor tissue-independent manner.

Revealing the presence of tear extracellular vesicles in Keratoconus

Extracellular vesicles (EVs) are lipid-bound vesicles that originate from the endosomal system or budded off from the plasma membrane. EVs are involved in cell-cell communication via transporting DNA, RNA, and proteins from one cell to another. Tear EVs (tEVs) have been reported in dry eye, Sjӧgren's Syndrome, and primary open-angle glaucoma. In this study, we sought to investigate the presence of tEVs in relation to keratoconus (KC). Tears were passively collected from the lateral meniscus from 10 healthy (5 males and 5 females) and 9 KC (4 males and 5 females) subjects. Tear samples were processed and analyzed using the ExoView™ R100. Statistical analysis was performed using a Mann-Whitney U non-parametric Student's t-test. All tEVs, in both Healthy and KC subjects, showed a CD9+ dominant tEV cohort independent of sex. A significant decrease in CD63+/CD9+ and CD63+/CD81+/CD9+ was found in the male KC tEVs (p < 0.05), but not in females compared to their healthy counterparts. Neither Healthy nor KC tEVs showed differences in the total number of tEVs, however significant differences were identified between the sexes (p < 0.05), with males having a higher number of tEVs. tEVs diameters ranged from 50 to 200 nm, in both Healthy and KC cohorts, with the majority in the 50-80 nm range suggesting exosome-dominant cohorts. To our knowledge, this is the first time, to date, that tEVs have been isolated and characterized in KCs. While further studies are warranted, the tEVs differences between KC and Healthy subjects suggest a potential role for tEVs in KC pathogenesis.

Single-cell atlas of keratoconus corneas revealed aberrant transcriptional signatures and implicated mechanical stretch as a trigger for keratoconus pathogenesis

Keratoconus is a common ectatic corneal disorder in adolescents and young adults that can lead to progressive visual impairment or even legal blindness. Despite the high prevalence, its etiology is not fully understood. In this study, we performed single-cell RNA sequencing (scRNA-Seq) analysis on 39,214 cells from central corneas of patients with keratoconus and healthy individuals, to define the involvement of each cell type during disease progression. We confirmed the central role of corneal stromal cells in this disease, where dysregulation of collagen and extracellular matrix (ECM) occurred. Differential gene expression and histological analyses revealed two potential novel markers for keratoconus stromal cells, namely CTSD and CTSK. Intriguingly, we detected elevated levels of YAP1 and TEAD1, the master regulators of biomechanical homeostasis, in keratoconus stromal cells. Cyclical mechanical experiments implicated the mechanical stretch in prompting protease production in corneal stromal cells during keratoconus progression. In the epithelial cells of keratoconus corneas, we observed reduced basal cells and abnormally differentiated superficial cells, unraveling the corneal epithelial lesions that were usually neglected in clinical diagnosis. In addition, several elevated cytokines in immune cells of keratoconus samples supported the involvement of inflammatory response in the progression of keratoconus. Finally, we revealed the dysregulated cell-cell communications in keratoconus, and found that only few ligand-receptor interactions were gained but a large fraction of interactional pairs was erased in keratoconus, especially for those related to protease inhibition and anti-inflammatory process. Taken together, this study facilitates the understanding of molecular mechanisms underlying keratoconus pathogenesis, providing insights into keratoconus diagnosis and potential interventions.

Distribution of Ocular Anterior and Posterior Segment Lengths Among a Cataract Surgical Population in Shanghai

Purpose: To investigate the distributions of the ocular anterior and posterior segment lengths among a cataract surgical population in Shanghai. Design: Cross-sectional study. Methods: Ocular biometric parameters of 23,462 eyes of 23,462 cataract surgery candidates were reviewed. Axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) were obtained using IOL Master. Anterior segment length (ASL = ACD + LT), posterior segment length (PSL = AL - ASL) and the ratio of ASL to PSL (ASL/PSL) were calculated. Results: The mean ASL was 7.58 ± 0.39 mm, the mean PSL was 17.12 ± 2.64 mm. As the age grew, the ASL increased, and PSL increased firstly then decreased. Male subjects tended to have significantly longer ASL and shorter PSL than female subjects. With the increasing AL, the ASL was firstly decreased to trough at 20-22 mm AL group, then increased gradually, while the PSL increased rapidly. The ASL correlated positively with AL in normal, moderate and highly myopic eyes, negatively in short eyes. The PSL correlated positively with AL across the entire study population. The ASL/PSL was not constant in the eyes with different AL but had a relatively steep downward trend with the increasing AL in the short eyes, then decreased smoothly in normal, moderate and highly myopic eyes. Conclusions: In Chinese cataractous eyes, longer ASL and shorter PSL were associated with elder age and male gender. The change of ASL over AL was not linear, and the ASL was smallest in the eyes with AL of 20-22 mm. The elongation of the eyeball was mainly due to the extension of the posterior segment.

A hospital-based study on clinical data, demographic data and visual function of keratoconus patients in Central China

China is a populous country but lacks epidemiological data on keratoconus (KC). The present study aimed to investigate the clinical data, demographic data, and visual function (VF) data of KC patients in Central China. A total of 524 KC eyes in 307 KC patients (217 bilateral and 90 unilateral) from Henan Eye Hospital were included in the current study. Demographic and VF data were assessed with questionnaires administered by well-trained staff during face-to-face interviews. Visual acuity value was examined by a qualified optometrist, and the clinical data were measured by professional clinicians. The distributions of sex, residence and education level of KC patients were compared by Chi-square tests, and the ratios of people wearing glasses and rigid gas permeable (RGP) lenses were compared by McNemar tests. General linear models/Chi-squared tests were used to compare the clinical and demographic data according to KC severity. Spearman’s correlation analysis was used to test the associations between the data and KC severity. The mean age at diagnosis was 20.98 ± 6.06 years, and males had a higher ratio of KC than females (P < 0.001). Patients in rural areas had a higher rate of KC than those in urban areas (P = 0.039), and the proportion of KC patients with a higher education level (above high school) was high (P < 0.001). A total of 68.40% of the patients reported eye rubbing and 3.52% had a positive family history. The percentage of people wearing glasses was higher than that of patients wearing RGP lenses (P < 0.001). The total VF score of KC patients was 69.35 ± 15.25. The thinnest corneal thickness (TCT) and stiffness parameter at the first applanation (SP-A1) values were inversely correlated with KC severity (P < 0.05). The mean, steep, and max keratometry (Km, Ks and Kmax) values, the RGP lens use and keratoplasty were positively correlated with KC severity (all P < 0.05). The total VF score of the eye with better VA decreased as the severity increased (r = − 0.21, P = 0.002). The present study comprehensively describes various associated features of KC patients from a tertiary hospital in Central China, providing a reference for understanding the characteristics of KC patients in China.

Ectatic diseases

Ectatic corneal disease (ECD) comprises a group of disorders characterized by progressive thinning and subsequent bulging of the corneal structure. Different phenotypes have been recognized, including keratoglobus, pellucid marginal degeneration (PMD), and keratoconus (KC). Keratoconus has been widely investigated throughout the years, but the advent of laser refractive surgery boosted an immediate need for more knowledge and research about ectatic diseases. This article discusses nomenclature of ectatic disease, etiology and pathogenesis, along with treatment options, with special focus ok KC and forme fruste keratoconus.

Normative Values of Various Pentacam HR Parameters for Pediatric Corneas

PURPOSE

To provide a normative database of several Pentacam parameters for a healthy pediatric population.

METHODS

This was a retrospective study conducted at Al Watany Eye Hospitals, Cairo, Egypt. We explored the Pentacam HR database and collected the data of 432 normal right eyes of children and teenagers aged 3 to 18 years. The subjects were classified into the following 3 groups: group 1 (3-6 years, 17 eyes), group 2 (6-12 years, 126 eyes), and group 3 (12-18 years, 289 eyes). The parameters of the study cohort were compared with those of a healthy adult cohort.

RESULTS

The mean age of the study cohort was 13.5 (13.2-13.8) years. There were significant differences in the following indices among the 3 age groups: anterior chamber (depth and volume), curvature (index of height decentration, index of vertical asymmetry, and center keratoconus index), elevation (front and back elevations from the best fit toric ellipsoid), and pachymetric (minimum and average pachymetric progression indices and average Ambrosio relational thickness) parameters (P values 0.001, 0.001, 0.002, 0.04, <0.001, <0.001, 0.03, 0.02, 0.01, and 0.03, respectively).

CONCLUSIONS

There were significant differences in the normative values of several Pentacam indices between the pediatric and adult cohorts. Based on this finding, it is more credible to incorporate separate software cutoff values for pediatric patients. However, because there were no clinically significant differences in the parameters of the pediatric subgroups, there is no need to consider a separate cutoff value for each pediatric age range.