Differences in keratoconus as a function of gender

Association Between Family History and the Corneal Characteristics of Keratoconus in Japan

PURPOSE

The aim of this study was to determine the association between family history and corneal characteristics of keratoconus in Japan.

METHODS

The clinical records of patients with keratoconus who were interviewed regarding family history of keratoconus were retrospectively reviewed. Corneal indices derived from anterior segment optical coherence tomography were compared between the positive and negative family history groups using multiple linear regression analysis adjusted with age, sex, and history of atopy and eye rubbing.

RESULTS

A total of 2,701 eyes, including 122 eyes with positive family history, were enrolled. Based on the adjusted multiple linear regression analysis, no significant differences were found between groups with and without a family history except for paracentral and mid-peripheral corneal thickness. The adjusted mean differences in paracentral and mid-peripheral corneal thicknesses between the two groups were -10.33 (95% confidence interval -20.29 to -0.37 P-value <0.05) and -9.78 (95% confidence interval -16.70 to -2.85, P-value <0.01), respectively.

CONCLUSIONS

There was no significant association between family history and corneal indices in Japanese patients with keratoconus, except for paracentral and mid-peripheral corneal thicknesses. A Japanese patient with keratoconus who had a family history showed significantly lower paracentral and mid-peripheral corneal thicknesses than those with no family history.

Factors associated with keratoconus in Israel-A cross-sectional population-based study

PURPOSE

To identify potential factors associated with keratoconus.

METHODS

This cross-sectional study included data from Israel's largest healthcare provider for the years 2005-2020. Keratoconus patients and age-matched controls were identified. Demographic factors and comorbid conditions, including smoking, diabetes mellitus, asthma, myalgia, mental retardation, Down syndrome, atopic dermatitis and allergy/allergic rhinitis, were compared between the two cohorts. The independent risk factors associated with keratoconus were determined using a multivariable conditional logistic regression model.

RESULTS

Overall, 145 508 subjects were reviewed of which 13 228 were keratoconus patients. A ten-fold group (n = 132 280) of age-matched control subjects served as controls for comparisons. In multivariable analysis, several factors were found to be significantly associated with keratoconus. Male gender (OR = 1.27, p < 0.001), Arab ethnicity (OR = 1.50, p < 0.001), diabetes (OR = 1.19, p < 0.001), asthma (OR = 1.50, p < 0.001), myalgia (OR = 1.09, p = 0.02), mental retardation (OR = 2.63, p < 0.001), atopic dermatitis (OR = 1.35, p < 0.001) and allergic rhinitis (OR = 1.21, p < 0.001) were significantly associated with keratoconus. Smoking was significantly protective of keratoconus (OR = 0.66, p < 0.001).

CONCLUSIONS

This population-based study reports male gender, Arab ethnicity, diabetes, asthma, myalgia, mental retardation/Down syndrome, atopic dermatitis and allergic rhinitis as factors associated with keratoconus while smoking demonstrates a protective effect. The results of this study could guide enhanced screening strategies and early interventions, particularly for high-risk groups.

Factors Associated With Receipt of Crosslinking for Keratoconus

PURPOSE

The aim of this study was to identify factors associated with receipt of standard fluence epithelium-off crosslinking (CXL) for keratoconus (KCN).

METHODS

This retrospective, cross-sectional study reviewed electronic health records of treatment-naive patients with KCN seen at the Wilmer Eye Institute between January 2017 and September 2020. Tomographic data were derived from Pentacam (Oculus, Wetzlar, Germany) devices. Multivariable population-average model using generalized estimating equations adjusting for age, sex, race, national area deprivation index, vision correction method, and disease severity was used to identify factors associated with receipt of CXL.

RESULTS

From 583 patients with KCN, 97 (16.6%) underwent CXL for KCN. Patients who received CXL in at least 1 eye were significantly younger (mean 24.0 ± 7.8 years) than patients who had never undergone CXL (33.4 ± 9.3 years) ( P < 0.001). In multivariable analysis, Black patients had 63% lower odds of receiving CXL for KCN (OR: 0.37, 95% CI, 0.18-0.79) versus White patients, and older age was protective against receipt of CXL (OR: 0.89 per 1-year increase, 95% CI, 0.86-0.93). Comparison of characteristics by race demonstrated that Black patients presented with significantly worse vision, higher keratometric indices (K1, K2, and Kmax), and thinner corneal pachymetry at baseline versus White or Asian patients.

CONCLUSIONS

In this clinical cohort of patients with KCN from a tertiary referral center, Black patients were less likely to receive CXL presumably because of more advanced disease at presentation. Earlier active population screening may be indicated to identify and treat these patients before they become ineligible for treatment and develop irreversible vision loss. Such strategies may improve health equity in KCN management.

Exosomes and their miRNA/protein profile in keratoconus-derived corneal stromal cells

Keratoconus (KC) is a corneal thinning disorder and a leading cause of corneal transplantation worldwide. Exosomes are small, secreted extracellular vesicles (30-150 nm) that mediate cellular communication via their protein, lipid, and nucleic acid content. We aimed to characterize the exosomes secreted by primary corneal fibroblasts from subjects with or without KC. Using human keratoconus stromal fibroblast cells (HKC, n = 4) and healthy stromal fibroblasts (HCF, n = 4), we collected and isolated exosomes using serial ultracentrifugation. Using nanoparticle tracking analysis (NTA) with ZetaView®, we compared the size and concentration of isolated exosomes. Different exosomal markers were identified and quantified using a transmission electron microscope (TEM) (CD81) and Western blot (CD9 and CD63). Exosomal miRNA profiles were determined by qRT-PCR using Exiqon Human panel I miRNA assays of 368 pre-selected miRNAs. Proteomic profiles were determined using a label-free spectral counting method with mass spectrometry. Differential expression analysis for miRNAs and proteins was done using student's t-test with a significance cutoff of p-value ≤0.05. We successfully characterized exosomes isolated from HCFs using several complementary techniques. We found no significant differences in the size, quantity, or morphology between exosomes secreted by HCFs with or without KC. Expression of CD81 was confirmed by immuno-EM, and expression of CD63 and CD9 with western blots in all exosome samples. We detected the expression of 72-144 miRNAs (threshold cycle Ct < 36) in all exosome samples. In HKC-derived exosome samples, miR-328-3p, miR-532-5p, miR-345-5p, and miR-424-5p showed unique expression, while let-7c-5p and miR-665 have increased expression. Protein profiling identified 157 proteins in at least half of the exosome samples, with 38 known exosomal proteins. We identified 12 up- and 2 down-regulated proteins in HKC-derived exosomes. The proteins are involved in membrane-bounded vesicles, cytoskeletal, calcium binding, and nucleotide binding. These proteins are predicted to be regulated by NRF2, miR-205, and TGF-β1, which are involved in KC pathogenesis. We successfully characterized the HKC-derived exosomes and profiled their miRNA and protein contents, suggesting their potential role in KC development. Further studies are necessary to determine if and how these exosomes with differential protein/miRNA profiles contribute to the pathogenesis of KC.

The prevalence of keratoconus in northern Poland: A cross-sectional study of patients from a primary healthcare practice

INTRODUCTION

Keratoconus is defined as central and/or paracentral corneal thinning and steepening with consequent irregular astigmatism. To date, no prospective study has reported its prevalence in Central Europe. This study aimed to evaluate the prevalence of keratoconus assessed with Scheimpflug imaging in a profile of general medicine practice in Poland.

METHODS

This cross-sectional study collected data by inviting all patients aged 10-80 years subscribed to a single general practitioner in the Elbląg area, Poland. Corneal measurements were performed using a rotating Scheimpflug corneal tomography system. Three masked examiners established the diagnosis of keratoconus in the right or left eye. Fleiss' kappa coefficient (κ) was used to qualitatively analyze the interexaminer agreement.

RESULTS

Of 1,705 patients invited to the study, 771 agreed to participate (45.2%). The mean age of the 728 patients (60.6% female and 39.4% male) with gradable images in at least one eye was 53.6 ± 16.5 years. All of the examiners classified the same four cases as keratoconus (0.549%, 549 per 100,000, 95% confidence interval 150 to 1,400 per 100,000), of which two were bilateral. Fleiss' kappa showed almost perfect agreement among the three examiners regarding the diagnostic decision (κ = 0.784, 95% confidence interval 0.750 to 0.817, p < 0.001). The keratoconus cases were all women (p = 0.106), aged 48, 69, 70, and 71 years old.

CONCLUSION

The prevalence of keratoconus in this area was higher than that previously demonstrated in many European countries. Underestimation of the prevalence has been postulated but never demonstrated.

Sequence variants contributing to dysregulated inflammatory responses across keratoconic cone surface in adolescent patients with keratoconus

Background

Keratoconus (KTCN) is the most common corneal ectasia resulting in a conical shape of the cornea. Here, genomic variation in the corneal epithelium (CE) across the keratoconic cone surface in patients with KTCN and its relevance in the functioning of the immune system were assessed.

Methods

Samples from four unrelated adolescent patients with KTCN and two control individuals were obtained during the CXL and PRK procedures, respectively. Three topographic regions, central, middle, and peripheral, were separated towards the whole-genome sequencing (WGS) study embracing a total of 18 experimental samples. The coding and non-coding sequence variation, including structural variation, was assessed and then evaluated together with the previously reported transcriptomic outcomes for the same CE samples and full-thickness corneas.

Results

First, pathway enrichment analysis of genes with identified coding variants pointed to "Antigen presentation" and "Interferon alpha/beta signaling" as the most overrepresented pathways, indicating the involvement of inflammatory responses in KTCN. Both coding and non-coding sequence variants were found in genes (or in their close proximity) linked to the previously revealed KTCN-specific cellular components, namely, "Actin cytoskeleton", "Extracellular matrix", "Collagen-containing extracellular matrix", "Focal adhesion", "Hippo signaling pathway", and "Wnt signaling" pathways. No genomic heterogeneity across the corneal surface was found comparing the assessed topographic regions. Thirty-five chromosomal regions enriched in both coding and non-coding KTCN-specific sequence variants were revealed, with a most representative 5q locus previously recognized as involved in KTCN.

Conclusion

The identified genomic features indicate the involvement of innate and adaptive immune system responses in KTCN pathogenesis.

Colombian Ocular Diseases Epidemiology Study (CODES): incidence and sociodemographic characterisation of keratoconus between 2015 and 2020

OBJECTIVE

To estimate the incidence and describe the demographic characteristics of keratoconus (KC) in Colombia using national health registry data between January 1st 2015 and December 31th 2020.

METHODS AND ANALYSIS

We conducted a nationwide, population-based study using the Integrated Social Protection Information System from the Colombian Ministry of Health, the unique official database in the country. We used the International Classification of Diseases code for KC (H186) to identify the number of new cases of KC and estimate the incidence rates both overall and according to age and sex. We made a standard morbidity ratio map to graph Colombia's morbidity risk of KC onset.

RESULTS

Of 50 372 424 subjects, 21 710 had KC between 2015 and 2020. However, due to the COVID-19 pandemic, all the incidence rates of this study were based on the 18 419 reported until 2019. The incidence rate in the general population was 10.36 (95% CI 10.08 to 10.64) per 100 000 inhabitants. The incidence peak among males was in their early 20s and females in their late 20s. The overall male to female incidence rate ratio was 1.60. Regarding the distribution of the disease, most cases were reported in Bogotá (48.64%), Antioquia (14.04%) and Cundinamarca (10.38%).

CONCLUSION

We performed the first nationwide, population-based study of KC in Latin America, finding distribution patterns similar to those reported in the literature. This study provides valuable information on the epidemiology of KC in Colombia, which is helpful in the development of policies for the diagnosis, prevention and treatment of the disease.

Socioeconomic Correlates of Keratoconus Severity and Progression

PURPOSE

The purpose of this study was to investigate the social determinants of health for keratoconus.

METHODS

In this retrospective cohort study of patients with keratoconus, the electronic health record was reviewed for keratometry, treatments received, clinical comorbidities, and social characteristics. Outcomes included severe keratoconus at presentation (steep keratometry ≥52 diopters), disease progression (≥0.75 diopters increase from the first to the most recent clinical visit), and corneal transplantation. Logistic regression was used to evaluate factors associated with severity at presentation and corneal transplantation. Cox proportional hazards modeling was used to evaluate progression.

RESULTS

A total of 1038 patients with keratoconus were identified, 725 (70%) of whom had baseline imaging. Compared with commercially insured patients, Medicaid recipients were more likely to have severe keratoconus, independent of social and clinical confounders [odds ratio (OR) 1.94, 95% confidence interval (CI), 1.12-3.35, P = 0.017]. Male sex was independently associated with progression (hazard ratio = 1.38, 95% CI, 1.03-1.84, P = 0.030). Medicare and Medicaid recipients were more likely to require transplantation compared with commercially insured patients (OR 2.71, 95% CI, 1.65-4.46, P < 0.001 and OR 1.74, 95% CI, 1.08-2.80, P = 0.022, respectively). Other social determinants of health, including non-White race/ethnicity, limited English proficiency, and unemployment, were associated with the outcomes only in univariate analysis. Obstructive sleep apnea, atopy, body mass index, and tobacco use were not associated with any outcome.

CONCLUSIONS

Socioeconomic factors were more consistent predictors of keratoconus severity and corneal transplantation compared with clinical factors that have received relatively greater attention in the keratoconus literature.

Investigating the role of inflammation in keratoconus: A retrospective analysis of 551 eyes

PURPOSE

Keratoconus (KCN), classically defined as a noninflammatory corneal ectasia, was recently associated with chronic inflammation. This study aimed to further evaluate the association between inflammation and KCN severity by assessing patient tear films.

METHODS

Retrospective chart review of consecutive patients (July 2016-February 2020) referred to a tertiary KCN centre. Using tomography Kmax values, the worst-eyes of patients with a diagnosis of KCN and tear film test results were included. Eyes were stratified as matrix metalloproteinase-9 (MMP9) positive or negative and analyzed using independent t and Pearson chi-squared tests. A p-value ≤ 0.05 was considered significant.

RESULTS

551 (51.40%) unilateral eyes were included. Mean age was 30.1 years and 70.1% were male. 55.5% of the eyes were MMP9 positive. Mean corrected distance visual acuity was 20/30^<συπ>-3</sup> Snellen and Kmax was 60.1 Diopters. MMP9 positive eyes had a higher Kmax (p = 0.048), and were more likely from patients who were male (p < 0.001), had a paediatric history of asthma (p = 0.042), and used glasses (p = 0.041). MMP9 negative eyes more likely corresponded to soft contact lens users (p = 0.012). No other significant differences were found in risk factors, topography, tomography, and tear film osmolarity.

CONCLUSION

MMP9 positive keratoconic eyes had significantly higher Kmax readings which may correlate with increased disease severity, supporting an association between keratoconus and inflammation. Further research is warranted to evaluate the role of targeted therapy and contact lens use on MMP9 levels in keratoconic eyes and whether disease progression is affected.

Disparities in Vision Health and Eye Care

Significant disparities in vision health and eye care exist. To achieve health equity, we must understand the root causes and drivers of health disparities and inequities, including social determinants of health and systemic racism.

Factors affecting quality of life in keratoconus

PURPOSE

To identify the factors affecting the quality of life (QoL) in adults with keratoconus, using the disease-specific Keratoconus Outcomes Research Questionnaire (KORQ).

METHODS

In this cross-sectional study, 574 patients with keratoconus completed the 29-item KORQ (18-item activity limitations and 11-item symptoms subscales) and demographic information. Based on mean corneal curvature to grade keratoconus severity, participants were categorised into four groups: mild <48 dioptres [D]; moderate: 48 to 53 D; advanced: 54 to 55 D and severe: >55D. Rasch analysis was used to assess the psychometric properties and to score the KORQ. Multivariable regression was performed to determine the independent impact of age, sex, laterality, severity and duration of keratoconus, education, employment status and mode of treatment for keratoconus on activity limitations and symptoms.

RESULTS

Mean (SD) age was 24.5 (5.1) years. 304 (53%), 160 (28%), 26 (4%) and 84 (15%) belonged to keratoconus groups 1, 2, 3 and 4, respectively. Rasch analysis demonstrated the 'activity limitations' and 'symptoms' KORQ subscales to possess good psychometric properties. Statistically significant associations were found between activity limitation score and the following measures: visual acuity (VA) in the better-seeing eye (r = -0.10, p = 0.01); VA in the worse-seeing eye (r = -0.09, p = 0.04) and ocular aberrations (r = -0.13, p = 0.008) in the worse-seeing eye. Statistically significant associations were also found between symptoms score and mean corneal curvature in the better-seeing eye (r = -0.10, p = 0.02). In regression models, female sex was associated with 21% worse symptom score than male (β = -0.33, 95% CI, -0.09, -0.59, p = 0.01) and working people experienced clinically and statistically significantly greater trouble from symptoms compared to those not working (β =0.44, 95% CI, 0.17, 0.70, p = 0.001).

CONCLUSIONS

People with keratoconus have poorer QoL in terms of activity limitations if they have poorer VA and greater wavefront aberrations, and in terms of symptoms if they are female and employed.

The Role of Estriol and Estrone in Keratoconic Stromal Sex Hormone Receptors

Keratoconus (KC) is a progressive corneal thinning disease that manifests in puberty and worsens during pregnancy. KC onset and progression are attributed to diverse factors that include: environmental, genetics, and hormonal imbalances; however, the pathobiology remains elusive. This study aims to determine the role of corneal stroma sex hormone receptors in KC and their interplay with estrone (E1) and estriol (E3) using our established 3D in vitro model. Healthy cornea stromal cells (HCFs) and KC cornea stromal cells (HKCs), both male and female, were stimulated with various concentrations of E1 and E3. Significant changes were observed between cell types, as well as between males and females in the sex hormone receptors tested; androgen receptor (AR), progesterone receptor (PR), estrogen receptor alpha (ERα), and estrogen receptor beta (ERβ) using Western blot analysis. E1 and E3 stimulations in HCF females showed AR, PR, and ERβ were significantly upregulated compared to HCF males. In contrast, ERα and ERβ had significantly higher expression in HKC's females than HKC's males. Our data suggest that the human cornea is a sex-dependent, hormone-responsive tissue that is significantly influenced by E1 and E3. Therefore, it is plausible that E1, E3, and sex hormone receptors are involved in the KC pathobiology, warranting further investigation.

Distribution of pediatric keratoconus by different age and gender groups

PURPOSE

To evaluate the distribution of pediatric keratoconus patients and the disease severity based on different age and gender groups in China.

MATERIALS AND METHODS

A total of 446 keratoconus eyes in 266 pediatric patients from January 2019 to January 2022 were included in the cross-sectional study. The clinical findings and severity of keratoconus were recorded and Kruskal-Wallis test, chi-squared test, and Cochran-Mantel-Haenszel (CMH) test were used to compare the parameters between different gender and age groups.

RESULTS

The male/female ratio was 353/93 (3.8:1), and the median age was 16 years (range: 6-17 years). Male patients were statistically younger than female patients (P = 0.041). The male/female ratio decreased with age (P for trend = 0.011). The distribution of the topographic keratoconus classification (TKC) stage was significantly different between gender and age groups (all P < 0.05). Male patients had a higher ratio of advanced keratoconus eyes (TKC ≥ 3) than female patients (P < 0.001), and CMH analysis indicated that being a male was a risk factor for advanced keratoconus after controlling for age (odds ratio: 2.581, P < 0.001).

CONCLUSION

Male keratoconus patients were younger, with a higher ratio of advanced keratoconus than female patients in the Chinese pediatric patients evaluated. Multicenter studies with larger sample sizes are necessary in the future.

Tomographic and aberrometric assessment of first-time diagnosed paediatric keratoconus based on age ranges: a multicentre study

PURPOSE

To describe paediatric keratoconus (KC) patients by tomographic and aberrometric characteristics at first diagnosis, in a multicentre study.

METHODS

We included 278 eyes from 139 paediatric patients, with a first tomographic diagnosis (Pentacam^® ) of KC prior to 18 years old. KC classification was based on the KC Index (≥ 1.07) and Topographic Keratoconus Classification (TKC ≥ 1). Patients were divided based on age ranges (14 and under and over 14 years) and gender. Statistical analysis was performed with SPSS statistics 25.0. ANOVA factor was carried out comparing to compare groups.

RESULTS

278 eyes were screened, and 230 eyes were diagnosed with paediatric KC. Mean age was 15.48 ± 2.33 (6 to 18) years. We found differences in terms of TKC (2.08 ± 0.89 and 2.38 ± 0.82, p < 0.05) and spherical aberration (-0.71 ± 0.97 and -1.07 ± 1.36, p < 0.05) among the 14 years old or under and above 14 years old groups, respectively. Overall, female paediatric KC patients presented a more severe TKC, Belin Ambrosio Display, maximum keratometry, asphericity and primary and secondary coma aberrations compared to male KC patients. We observed a correlation between CDVA and asphericity (r = 0.71, p < 0.01), as well as between CDVA and spherical aberration (r = 0.69, p < 0.01).

CONCLUSION

Our findings revealed that the debut of KC is usually in a moderate to advanced stage in the paediatric population at first diagnosis, particularly in female patients. Corneal tomography should be systematically performed in children with recent onset of corneal astigmatism.

Estimated Prevalence of Keratoconus in the United States From a Large Vision Insurance Database

PURPOSE

To estimate the prevalence of keratoconus in the United States using a large vision insurance database.

METHODS

We used data from the 2016 vision service plan (VSP) Global claims database to estimate the prevalence of keratoconus among enrollees by state. The VSP Global database includes cross-sectional de-identified claims data summarized by state of residence in predefined age and gender groups. Crude values of prevalence of keratoconus are provided in the VSP Global database. The open-source software package qGIS version 3.12 was used as the geographic information system for geospatial analysis.

RESULTS

The prevalence of keratoconus among VSP enrollees in the United States was estimated to be 0.15% with 95% confidence interval (CI) (0.15%, 0.15%). The prevalence of keratoconus was highest in Western states and among male population. The highest prevalence of keratoconus was in Colorado (0.51%; 95% CI 0.49%-0.52%), with particularly high prevalence for men in the age groups 18 to 39 years (0.90%; 95% CI 0.84%-0.95%) and 40 to 64 years (0.90%; 95% CI 0.85%-0.95%).

CONCLUSION

The average prevalence of keratoconus in the United States in 2016 may be higher than previously reported. Living in Western states and male sex were associated with high prevalence.

Association of Collagen Gene (COL4A3) rs55703767 Variant With Response to Riboflavin/Ultraviolet A-Induced Collagen Cross-Linking in Female Patients With Keratoconus

PURPOSE

To investigate for the first time the association of collagen COL4A3 (rs55703767), COL5A1 (rs7044529), and COL4A4 (rs2229813) variants with response to corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A in patients with keratoconus (KC).

METHODS

A total of 147 eligible patients with KC were genotyped for the specified collagen variants using real-time TaqMan-based polymerase chain reaction. Adjusted odds ratio (OR) with 95% confidence interval (CI) was applied to assess the strength of the association with response to CXL for a decrease in maximum keratometry and/or an increase in corneal thickness.

RESULTS

Eighty-two patients (55.8%) had post-CXL successful outcomes. The overall analysis revealed that minor allele frequencies of COL4A3, COL5A1, and COL4A4 variants were 0.22, 0.22, and 0.38, respectively. The G/T genotype of the COL4A3 variant was more prevalent in the successful group (43%) compared with the failure group (23%) (P < 0.001). COL4A3 (rs55703767) was associated with a good response under heterozygote (OR: 2.19, 95% CI, 1.04-4.59, P < 0.001) and overdominant (OR: 2.59, 95% CI, 1.25-5.38, P = 0.008) models. By contrast, COL5A1 and COL4A4 variants were not associated with the effective response after CXL treatment. Interestingly, stratification analysis by sex revealed that CXL was more successful in female patients with KC under heterozygote (OR: 4.71, 95% CI, 1.74-12.75), dominant (OR: 3.16, 95% CI, 1.29-7.78), and overdominant (OR: 5.18, 95% CI, 1.92-13.95) models for COL4A3 (rs55703767) variant.

CONCLUSIONS

The COL4A3 (rs55703767) variant, among other study variants, could be implicated in CXL riboflavin/ultraviolet A treatment response in patients with KC in the study population. Large-scale replication and follow-up studies in different ethnic groups are warranted.

Prevalence and incidence of keratoconus in Norway: a nationwide register study

PURPOSE

To estimate the national prevalence and incidence of keratoconus in Norway.

METHODS

In this epidemiologic study, data were obtained from the Norwegian Patient Registry, which provides information from all publicly funded specialist care in Norway. Prevalence of keratoconus was estimated from the total number of patients registered with this diagnosis and incidence from the annual frequency of first-time registrations of patients up to 40 years of age in the period 2010-2018. Data on age and gender of the keratoconus patients were also gathered.

RESULTS

A total of 9832 keratoconus patients were registered. The estimated prevalence in the general population was 192.1 per 100 000 (95% confidence interval (CI): 188.3-195.9), and the estimated annual incidence was 19.8 per 100 000 (95% CI: 18.1-21.5). There was a predominance of males (73%), and mean age for all patients was 37.5 years at first registration in this period.

CONCLUSION

This study reports the frequency of keratoconus from a national patient register during a time period with available modern diagnostic tools. The estimated prevalence and incidence were higher than most previous estimates and show that keratoconus is not a rare condition. As screening was not part of the study, the true prevalence in the general population may be even higher.

Corneal transplantation for keratoconus in South Korea

This nationwide population-based study investigated the incidence rate of and risk factors for the progression to corneal transplantation in patients with keratoconus in South Korea using claims data from the Health Insurance Review and Assessment service. Among the entire South Korean population, 10,612 patients newly diagnosed with keratoconus between January 2010 and June 2015 were identified and included in the study. During the study period, 124 patients (1.17%) underwent corneal transplantation, with an average follow-up period of 2.97 ± 1.59 years. The incidence rate of corneal transplantation in patients with keratoconus was 4.46 cases per 1000 person-years. The rate of corneal transplantation for keratoconus was relatively low in South Korea compared to other countries. Multivariate Cox regression analysis revealed that male sex (HR 2.37; 95% CI 1.61–3.50; P < 0.001), severe atopic dermatitis (HR 2.32; 95% CI 1.02–5.28; P = 0.044), obstructive sleep apnea (HR 9.78; 95% CI 1.36–70.10; P = 0.023), and intellectual disability (HR 4.48; 95% CI 1.33–15.11; P = 0.016) significantly increased the risk of progression to corneal transplantation. In patients with keratoconus, male sex, severe atopic dermatitis, obstructive sleep apnea, and intellectual disability were associated with an increased risk of corneal transplantation.

Prevalence of keratoconus in persons with Down syndrome: a review

Purpose

Keratoconus is a vision-threatening condition, and there is a need for knowledge about the occurrence in subgroups of the population. The progression of the disease can be effectively stopped, and vision may be restored, if keratoconus is diagnosed at an early stage. The purpose of this review was to evaluate the literature of the prevalence of keratoconus in persons with Down syndrome.

Methods

We conducted a literature review of keratoconus prevalence in persons with Down syndrome. A thorough search was performed in Pubmed (Medline), and the quality of evidence was evaluated.

Results

The literature review identified 20 relevant studies, which reported keratoconus in 0%–71% of persons with Down syndrome. These studies varied greatly in design, patient selection, sample sizes and mean age, and the quality of evidence concerning estimates for the prevalence of keratoconus was generally evaluated as low. Most studies that included adults reported high prevalences of keratoconus–in many studies more than 10-fold the prevalence in the general population. No large screening studies in persons with Down syndrome were identified.

Conclusions

The present review showed that the prevalence of keratoconus in persons with Down syndrome is higher than in the general population. However, estimates from previous studies vary widely. Screening for keratoconus in this group should be considered.

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.

Characteristics of Keratoconus Patients in Jordan: Hospital-Based Population

PURPOSE

To study the demographic, clinical and topographic characteristics of keratoconus patients in Jordan.

METHODS

A retrospective study which was conducted at King Abdullah University Hospital, Northern Jordan. The patients who visited our outpatient clinic from March 2015 to September 2020 and had a definite diagnosis of keratoconus were included in this study. Demographic and clinical data, including age, gender, family history, past ocular history, ophthalmic examination, and topographic parameters, were collected and analysed. Keratoconus severity was classified according to K mean readings.

RESULTS

A total of 234 patients with keratoconus were evaluated in this study. The majority of patients (73, 31.2%) were between the ages of 20 and 24. Allergic conjunctivitis was the most frequent past ocular history. Fifty-five patients (23.5%) had a family history of keratoconus. Regarding severity, most of the eyes were mild (63.3%), followed by moderate (24.7%), and then severe (11.9%). The severity of keratoconus was significantly associated with gender (p<0.001). No correlation was found between family history and severity.

CONCLUSION

Most of the Keratoconus patients were young, with a mean age of 25.9 years. The majority were mild in severity, with more females presented in the severe stage. The study reported high rate of family history (23.5%) in comparison to similar studies. Therefore, screening of family members of Keratoconus patients is advisable.

A review of corneal imaging methods for the early diagnosis of pre-clinical Keratoconus

BACKGROUND

Keratoconus (KC) is a corneal ectasia characterised by steepening corneal curvature, changes in refractive error and corneal thickness that result in visual impairment. Early signs of KC include displacement of the thinnest part of the cornea from the central position, changes in the corneal epithelial layer cell distribution, variations in the anterior corneal astigmatism/posterior corneal astigmatism relationship and a variation in corneal thickness. It is important that we review the corneal imaging methods for the diagnosis of preclinical KC.

METHOD

An online literature search was carried out on PubMed. Only publications detailing corneal assessment procedures were considered for this review and any publication on instruments that did not generate KC predictability indices were also excluded from the review. The 308 publications were reviewed.

DISCUSSION

Corneal assessment techniques, with the ability to characterise both the anterior and posterior corneal surfaces, are invaluable in the diagnosis of pre-clinical KC. Reflection based and elevation based corneal imaging systems should be used in conjunction with other assessments such as higher order aberration measuring systems to improve sensitivity and reliability in the diagnosis of pre-clinical KC. Ultra high resolution ultrasound can detect pre-clinical KC. The ability to asses both the epithelium and endothelium makes anterior surface optical coherence tomography a superior technique for pre-clinical KC diagnosis. There is a positive correlation between central corneal thickness and corneal hysteresis. Corneal biomechanics should be considered in conjunction with other corneal assessments in the diagnosis of pre-clinical KC.

Do age-related macular degeneration genes show association with keratoconus?

Background

Keratoconus (KC) is a common corneal condition with an unknown gender predominance. Although numerous studies have investigated the genetic component of KC, no specific genes have yet been attributed to the condition. We recently reported posterior segment changes occurring in the eyes of KC patients. However, it is not clear whether these changes are part of KC pathogenesis or reflect changes in anatomical features of the eye manifested by changes at the cornea. Given retinal changes represent the main characteristics observed in age-related macular degeneration (AMD) and that pleiotropy has been demonstrated between different eye diseases, we wished to assess if known AMD associated genes were also associated with KC.

Methods

A total of 248 KC subjects and 366 non-KC (control) subjects were recruited from public and private clinics in Melbourne for this analysis. Nineteen single nucleotide polymorphisms (SNPs) previously associated with AMD, including rs10490924 (ARMS2/HTRA1), rs10737680 (CFH), rs13278062 (TNFRSF10A), rs1864163 (CETP), rs2230199 (C3), rs3130783 (IER3/DDR1), rs334353 (TGFBR1), rs3812111 (COL10A1), rs429608 (C2/CFB), rs4420638 (APOE), rs4698775 (CFI), rs5749482 (TIMP3), rs6795735 (ADAMTS9), rs8017304 (RAD51B), rs8135665 (SLC16A8), rs920915 (LIPC), rs943080 (VEGFA), rs9542236 (B3GALTL) and rs13081855 (COL8A1/FILIP1L), were genotyped in this cohort. Logistic regression was applied to evaluate the association between these SNPs and KC on both genders together, as well as each gender separately. Linear regression was also applied to assess the association between SNPs and corneal curvature. Bonferroni correction was applied to adjust for multiple testing.

Results

Genotyping data were available for 18 SNPs. The SNP, rs6795735 (ADAMTS9) was significantly associated with KC (p = 3.5 × 10^- 4) when both genders were assessed, whereas rs5749482 (TIMP3) was only associated in males (p = 7.7 × 10^- 4) following Bonferroni multiple correction. However, when the covariates of age and gender were included, the associations became non-significant. In addition, none of the SNPs appeared significant for corneal curvature.

Conclusions

Our study suggested a potential association of rs6795735 in the ADAMTS9 gene and rs5749482 in the TIMP3 gene in KC and that different associations may be gender specific. Overall, SNPs initially identified as associated with AMD following multiple correction may be further impacted by other factors such as age or gender and further studies are needed to resolve this issue.

Macular thicknesses in patients with keratoconus: An optical coherence tomography study

Background: Keratoconus, a corneal ectasia associated with thickness and structural changes, has been reported to co-exist with posterior segment ocular conditions. However, very few studies have reported on macular thicknesses in individuals with keratoconus.Aim: The aim of this study was to investigate macular thicknesses in participants with keratoconus.Setting: This study was conducted at the University of KwaZulu-Natal (UKZN).Methods: A comparative cross-sectional research design was used. The sample consisted of 88 participants with 44 each in the control and keratoconus (15, 11 and 18 with mild, moderate and severe keratoconus, respectively) groups. Macular thicknesses were obtained with the Fourier-domain Optovue iVue100 optical coherence tomographer using the nine Early Treatment Diabetic Retinopathy Study sectors. Data were analysed using descriptive and inferential statistics.Results: Overall, the mean macular thicknesses were comparable among the control and three keratoconus groups (p ≥ 0.199). The mean central foveal thickness was greater in the severe keratoconus group (259 µm) than the other three study groups that showed similar measurements (247 µm – 248 µm). The central fovea was thinnest followed by the perifovea and parafovea in all four study groups. The mean thickness in the nasal and temporal quadrants of the parafovea and perifovea was thickest and thinnest, respectively, in all four study groups.Conclusion: Macular thicknesses via optical coherence tomography in individuals with keratoconus and controls are similar with thickness differences that are clinically insignificant. Consequently, macular thicknesses should be included in the preoperative assessment of individuals with keratoconus awaiting corneal transplantation to assess the integrity of the retina prior to surgery.

[Epidemiology of keratoconus in different countries]

The scientific problem of epidemiology of keratoconus in different countries is covered in the article. The results of original studies were analyzed and a conclusion has been drawn that keratoconus is quite a common disease in the world.

The impact of keratoconus treatment with the Athens Protocol (partial topography-guided photorefractive keratectomy combined with higher-fluence corneal collagen cross-linking) on quality of life: a long-term study

Purpose

The aim of this study was to evaluate the health-related quality of life (HRQoL) before and after the management of keratoconus (KCN) with Combined Topography-Guided Transepithelial partial photorefractive keratectomy (PRK) and corneal Cross-Linking: the Athens Protocol.

Patients and methods

Thirty-four consecutive patients treated for progressive KCN were selected for retrospective telephone interview and individual questionnaire submission. A disease-specific HRQoL questionnaire was administered before and after the Athens Protocol intervention, using the following administrative questionnaires: National Eye Institute Visual Function Questionnaire (NEI VFQ) 25/39 and IVI-28. The disease grade was ranked according to the Amsler–Krumeich classification (KCN severity). Reliability of collected data was evaluated with Cronbach’s α test.

Results

Patients’ age ranged from 15 to 51 years at the time of the operation. Mean time before the operation during which the questionnaires were administered was 52±6 months. General visual acuity, psychological well-being, and driving ability showed significant improvement. Younger keratoconic patients tend to have more enhanced psychological status and to cope better with difficulties in everyday activities (prior to operation) than older patients.

Conclusion

The Athens Protocol treatment has been proven to be beneficial to patients in a large number of aspects.

Prevalence of Keratoconus in a Refractive Surgery Population

Objective

This study examined the prevalence of keratoconus among patients who were interested in undergoing refractive surgery. Corneal tomography measurements were used to help detect keratoconus.

Methods

Adult subjects who presented to the private hospital Cataract and Refractive Surgery Unit (Abha, Saudi Arabia) for refractive surgery evaluation were considered for inclusion in this cross-sectional, retrospective study. All subjects were from the Aseer province, a southern, high-altitude region in Saudi Arabia, and presented between January and December 2017. The incidence of keratoconus and other refractive surgery contraindications were examined.

Results

A total of 2931 patients were considered for inclusion in analyses. Of these, 2280 patients (77.8%) were not candidates for refractive surgery. These 2280 patients had a mean age of 24.1 ± 6.6 years and 1231 patients (54.0%) were male. Of the subjects who did not undergo refractive surgery, 548 (24%) had keratoconus, 400 (17.5%) were keratoconus suspects, 344 (15.1%) had thin corneas, 321 (14.1%) had high myopia, and 52 (2.3%) had a high astigmatism. An additional 479 subjects (21%) were candidates for refractive surgery, but chose not to undergo a procedure.

Conclusion

The incidence of keratoconus in Saudi Arabian refractive surgery prospects was 18.7%. Keratoconus was the most common reason for not performing refractive surgery and accounted for 24.0% of cases in which surgery was not performed.

Prevalence and Incidence of Keratoconus in South Korea: A Nationwide Population-based Study

PURPOSE

To determine the prevalence and incidence of keratoconus in South Korea.

DESIGN

A nationwide, population-based, retrospective study of keratoconus in the entire South Korean population (N = 47 990 761) from 2009 to 2014 was conducted using data from the Korean Health Insurance Review and Assessment (HIRA) database.

METHODS

We identified patients with ophthalmologist-confirmed keratoconus using the HIRA database, and estimated keratoconus prevalence and incidence rates, both overall and according to age and sex.

RESULTS

Of 47 990 761 subjects, 17 931 had keratoconus during the 6-year period. The prevalence in the general population was 37.4 cases (95% confidence interval [CI]: 36.8-37.9) per 100 000 people. After exclusion of an initial 1-year washout period, 13 343 cases of incident keratoconus were identified during the final 5-year period (2010-2014). The incidence rate in the general population was 5.56 cases (95% CI: 5.47-5.66) per 100 000 person-years. Incidence peaked among men in their late 20s and among women in their early 20s. The overall male-to-female incidence rate ratio was 1.00, meaning there was no sex predisposition.

CONCLUSION

Estimates of the nationwide, population-based prevalence and incidence of keratoconus may help deepen our understanding of the pathophysiology of the disease and allow appropriate healthcare system planning.

Female Hormone 17β-Estradiol Downregulated MMP-2 Expression and Upregulated A1PI Expression in Human Corneal Stromal Cells

Collagens are essential for cornea functions. In non-ocular tissues, it has been demonstrated that sex hormones modulate the collagen remodeling. In this study, we investigated whether the primary female hormone 17β-estradiol plays a role in the expressions of matrix metalloproteinases and proteinase inhibitors in cultured human corneal stromal cells. We found that 17β-estradiol treatment significantly reduced the matrix metalloproteinase-2 mRNA in human corneal stromal cells as well as the matrix metalloproteinase-2 proteins, while the matrix metalloproteinase-9 mRNA level was not significantly altered. 17β-estradiol also upregulated the expression of proteinase inhibitor, alpha1-proteinase inhibitor. The expression of transcription factor specificity protein 1 was reduced by 17β-estradiol. Furthermore, 17β-estradiol did not change the viability and apoptosis of the corneal stromal cells. The downregulation of matrix metalloproteinase-2 and upregulation of alpha1-proteinase inhibitor by 17β-estradiol possibly serve as protective factor for the normal tomography in antagonizing the extracellular matrix degeneration in many cornea diseases.

Clinical Profile of Omani Keratoconus Patients: An Experience from a tertiary referral centre in Muscat

OBJECTIVE:

To determine the demographics and associated clinical features of Omani keratoconus patients presenting to the Ministry of Defence Hospital (MODH) in Muscat.

METHODS:

This is a retrospective, descriptive study whereby the electronic medical records of all Omani keratoconus patients presenting to the MODH between January 2011 and December 2015 were reviewed. Demographic details, corrected distance visual acuity, refraction, corneal topography, pachymetry, and treatment received were all documented.

RESULTS:

There were 458 new keratoconus patients (257 males, 201 females) comprising a total of 893 eyes with a mean age of 20 years ± 5.6 (standard deviation) (range 6–46 years). On their first visit, 35% of eyes had spectacle-corrected distance visual acuity <0.5 logarithm of the minimum angle of resolution (LogMAR), 38% had central corneal thickness <450 um, and 25% had a mean keratometry more than 53 Diopter (D). According to the Amsler-Krumeich classification, 37%, 30%, 18%, and 16% of eyes classified into stages I, II, III, and IV, respectively. The severity of keratoconus did not correlate with the age of patients (rs = −0.13, P < 0.05). Over the 5-year period of the study, 502 eyes were fitted with rigid gas permeable lenses with 91% achieving the vision of 0.1 LogMAR or better, 22% of eyes underwent collagen cross linking, 3% underwent intracorneal ring segments implantation, and 4% underwent corneal grafting.

CONCLUSION:

A significant proportion of Omani keratoconus patients seen in the MODH showed advanced disease on their first visit. There was no correlation between severity and age suggesting that keratoconus can progress quickly in our pediatric group. Population-based studies are an important next step. Meanwhile, early detection and timely interventions to limit the burden of the disease are crucial.

Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study

AIM

To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography.

METHODS

This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1) was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2) and Bogan's classification was used to group eyes into those with regular or no astigmatism (GRI) and irregular astigmatism (GRII). Test 1 provided a single absolute value for the greatest cylinder difference (Vr). The receiver operating characteristic (ROC) were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated.

RESULTS

The study sample was comprised of 260 eyes (135 patients). The prevalence of irregular astigmatism was 42% [95% confidence interval (CI): 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D) for GRI and 1.75 D (25% quartile, 1.25 D) for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%.

CONCLUSION

A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

Characteristics of Keratoconic Patients Attending a Specialist Contact Lens Clinic in Kenya

PURPOSE:

To describe the characteristics of keratoconus (KC) patients seen in a contact lens clinic of a children's hospital in Kenya.

RESULTS:

A total of 254 patients’ records were analyzed. Mean age at presentation to the clinic was 20.97 ± 11.13 year (range, 6–84 years) with 75% between the ages of 6 and 25 years. There was a preponderance of males (59.8%). Most patients were referred by an ophthalmologist. All patients were Africans. The most common complaints were blurred vision (50%), poor visual acuity with spectacles (33.5%), contact lens intolerance (11.8%), and other (unspecified). Most cases were severe (71%) followed by moderate (22.9%) and mild (6.2%). Mean BCVA was 0.24 ± 0.23 (6/11). An optical correction was provided in 98% of cases; 34.6% with spectacles, 31.1% with gas permeable lenses and the remaining with both. Referral for keratoplasty was warranted in 16.5%.

CONCLUSION:

This is the first study of KC conducted in Kenya. KC presented at a very early age and tended to be severe. Ophthalmologists were the main source of referral. The main presenting symptom was reduced vision. Optical correction was the most common management and the percentage of patients referred for surgery concurred with other studies.

[Freiburg keratoconus registry : Example of application of smart data for clinical research and inititial results]

BACKGROUND

Keratoconus is a progressive corneal disease with thinning and scarring of the cornea. Diagnostic and treatment options are usually evaluated in large prospective or retrospective trials. Big data and smart data provide the possibility to analyze routine data for clinical research. In this article we report the generation of a monocentric keratoconus registry by means of computerized data analysis of routine data. This demonstrates the potential of clinical research by means of routine data.

METHODS

A "clinical data warehouse" was created from all available routine electronic data. At the time of first presentation, each eye was classified into one out of four categories: suspected, early disease, late disease and status postkeratoplasty. Through integration of multiple data sources the clinical course for each patient was documented in the registry.

RESULTS

A total of 3681 eyes from 1841 patients were included. The median follow-up time was 0.54 years. Patient age was higher in the groups with more severe stages of keratoconus, the proportion of female patients was higher in the group of suspected keratoconus and patient age and male to female ratios showed statistically significant differences between the groups (p < 0.001).

CONCLUSION

We were able to create a "clinical data warehouse" by linking multiple data sources and normalizing the data. With this tool we established a novel, monocentric keratoconus registry. Only the grading of disease severity and the exclusion of false positive results were carried out manually. In our opinion establishing a structured clinical data warehouse has a huge potential for clinical and retrospective studies and proves the value of the Smart Data concept.

Association between Family History and Keratoconus Severity

PURPOSE

The high prevalence of positive family history of keratoconus (KC) in KC patients is well-known. However, the results regarding the association between family history of KC and disease severity are controversial. The aim of this study was to evaluate the possible association between family history and severity of KC.

METHOD

Clinical data of 1496 KC patients were evaluated. All participants were asked if they had had a family member with KC. Topographic and keratometric measurements of KC patients, including central corneal thickness (CCT), thinnest corneal thickness (TCT), mean, flat, and steep keratometry values (K) by the use of Pentacam, best-spectacle corrected visual acuity (BCVA), spherical equivalent (SE), and astigmatism were recorded and compared according to patients with and without a family history of KC, first- or second-degree family members, and the number of family members with KC. Severity of KC was classified according to the Amsler-Krumeich classification.

RESULTS

Family history of KC was present in 292 (19.5%) patients. Of those 292 patients who had a family history of KC, 159 (54.5%) had one family member with KC and 133 (45.5%) had two or more family members with KC. There was not a significant difference between corneal pachymetry and K values of the patients with and without a family history of KC (p > 0.05). However, those with a positive family history of KC had more severe disease, according to the Amsler-Krumeich classification (p < 0.05). KC patients who had more family members with KC had significantly lower TCT and significantly higher steep K and astigmatism (p < 0.05), and had more severe disease, according to the Amsler-Krumeich classification (p < 0.05).

CONCLUSION

We suggest that patients with more family members with KC should be subject to screening to identify early disease.

Endocrine and Metabolic Pathways Linked to Keratoconus: Implications for the Role of Hormones in the Stromal Microenvironment

Hormones play a critical role in regulating tissue function by promoting cell survival, proliferation, and differentiation. Our study explores the influence of endocrine function in regulating metabolism and inflammatory pathways in Keratoconus (KC), which is a corneal thinning disease associated with reduced stromal deposition. KC is known to be a multifactorial disease with an elusive pathogenesis. We utilized a cross-sectional study analyzing clinical features and saliva samples from sixty-four KC patients and fourteen healthy controls. In order to determine if endocrine function varied between healthy controls and KC, we measured hormone levels in saliva and found significantly increased dehydroepiandrosterone sulfate (DHEA-S) and reduced estrone levels in KC patients compared to healthy controls. We measured significant variations in metabolites associated with pro-inflammatory processes, including myoinositol and 1-methyl-histidine, by targeted mass spectrometry. We also measured significantly increased IL-16 and stem cell factor in KC saliva samples compared to healthy controls, with higher expression of these pro-inflammatory proteins correlating with increased KC clinical grade, corneal curvature, and stromal thinning. Our results identify a novel mechanism linking KC and pro-inflammatory markers and suggest that altered hormone levels modulate metabolism, cytokine, and growth factor expression leading to increased severity of the KC condition.

The genetic and environmental factors for keratoconus

Keratoconus (KC) is the most common cornea ectatic disorder. It is characterized by a cone-shaped thin cornea leading to myopia, irregular astigmatism, and vision impairment. It affects all ethnic groups and both genders. Both environmental and genetic factors may contribute to its pathogenesis. This review is to summarize the current research development in KC epidemiology and genetic etiology. Environmental factors include but are not limited to eye rubbing, atopy, sun exposure, and geography. Genetic discoveries have been reviewed with evidence from family-based linkage analysis and fine mapping in linkage region, genome-wide association studies, and candidate genes analyses. A number of genes have been discovered at a relatively rapid pace. The detailed molecular mechanism underlying KC pathogenesis will significantly advance our understanding of KC and promote the development of potential therapies.

Vision related quality of life in patients with keratoconus

Purpose. The purpose of this study is to evaluate the vision related quality of life in patients with keratoconus by using the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25). Methods. Thirty patients presented with keratoconus (keratoconus group) and 30 healthy patients (control group) were included in this study. Twenty patients were using rigid gas permeable and 10 patients were not using contact lenses in keratoconus group. High and low contrast visual acuity and mean K values of the patients were recorded. Each subject completed the 25-item NEI-VFQ-25. Results. All subscales of NEI-VFQ-25 were lower in the keratoconus patients. The difference was more evident in the subscales of general vision, ocular pain, near vision, vision-specific mental health, vision-specific role difficulties, and peripheral vision (P < 0.05). Overall composite score was 75.2 ± 17.2 in the keratoconus group and 93.2 ± 5.6 in the control group (P = 0.00). Contact lens wearers had higher best corrected visual acuity in comparison with noncontact lens wearers (P = 0.028). Patients with low visual acuity (logMAR > 0.4) in the better eye had lower distance vision, social functioning, mental health, and role difficulties. Meanwhile, patients with low visual acuity (logMAR > 0.4) in the worse eye had lower general health scores (P < 0.05). Conclusions. Vision related quality of life was worse in keratoconus patients. Success in the contact lens usage and maintaining higher visual acuity may improve vision related quality of life.

Quo vadis older keratoconus patients? Do they die at younger ages?

PURPOSE

To examine the validity of the observations made by specialist corneal surgeons that there seems to be an absence or loss of older patients with keratoconus (KC).

METHODS

Using a PubMed search and key words such as KC, epidemiology, mortality, mitral valve prolapse, atopy, and asthma, the literature related to this topic was reviewed. Specialist contact lens fitting practitioners were asked to supply age-related details of KC and nonkeratoconus patients within their practices.

RESULTS

Results suggested a marked absence or loss of older KC patients as has been observed by specialist corneal surgeons. Several possible explanations are described including increased mortality associated with mitral valve prolapse, asthma, obesity, and/or obstructive sleep apnea, for example. In addition, gender bias, the influence of progression to keratoplasty or age-related diseases, as well as difficulty in traveling to specialist practices and the need for and dependence on specialist contact lens fitting skills of KC patients were considered. The possibility that KC corneas could improve with age-related increased natural crosslinking and stiffening is discussed.

CONCLUSIONS

An absence or loss of older KC patients has been found in some specialist contact lens fitting practices. Notwithstanding the possible influence of numerous other issues, the absence or loss of KC patients may be because of reduced life expectancy, a topic that seems to warrant further examination. There may be implications for improving the understanding of the pathogenesis of KC if reduced life expectancy can be confirmed and the associated reasons elucidated.

Clinical characteristics of keratoconus patients in Malaysia: a review from a cornea specialist centre

Purpose

To evaluate the demographic profile, refraction, visual acuity (VA), corneal curvature (K) and severity of keratoconus (KC) patients from a cornea specialist centre in Malaysia. This may improve the management of KC patients in this country.

Methods

Records of 13,000 patients were reviewed. The patients were categorized into 4 age groups: (Gp 1: <23 years, Gp 2: 23–32 years, Gp 3: 33–42 years, Gp 4: >42 years). Refraction and VA were determined using subjective refraction and Snellen chart. Corneal curvature was measured using Orbscan II topography. Severity of KC was graded following Amsler–Krumeich system. Data were analysed according to age, gender and ethnicity.

Results

A total of 159 patients had KC and the prevalence was 1.2%. Mean age of onset was 20.9 ± 5.6 years, with 71.1% of males and 28.9% of females. Majority were of Indian and Malay origins. Percentages of patients within each age group were 26.4%, 52.8%, 18.9% and 1.9% respectively. Regarding severity, 37.6% were stage I, 30.1% stage II, 4.4% stage III and 27.8% stage IV at the time of diagnosis. The age of onset, refraction, mean K and VA was found to be similar between gender and ethnicity (p > 0.05). Age of onset was not strongly correlated to the severity of the disease.

Conclusion

This study concludes that there are higher percentages of Malays and Indians with KC than other races in Malaysia. The condition was found to manifest at a younger age and was more common in males than females. These findings should be considered during vision screening in Malaysia.

The influence of gender and hormone status on the severity and progression of keratoconus

PURPOSE

To assess the effects of gender and hormone status on the severity and progression of keratoconus in patients enrolled in the Collaborative Longitudinal Evaluation of Keratoconus Study.

METHODS

The severity and progression of keratoconus in both men (M) and women were evaluated over a 4-year period that encompassed menopausal transition for hormone-active women (HA) and hormone-inactive women (HI). Four outcome measures were selected as indicators of the severity of keratoconus: high-contrast best-corrected visual acuity, low-contrast best-corrected visual acuity, the steep keratometric measurement, and corneal scarring (yes/no).

RESULTS

There were no statistically significant differences among the 3 groups (M, HA, and HI) in race, history of atopic disease, family history of keratoconus, or rigid contact lens wear in the right and left eyes. At baseline, there were no significant differences among the 3 groups in high-contrast best-corrected visual acuity, low-contrast best-corrected visual acuity, or steep keratometric reading. Progression of keratoconus, as assessed by changes in these 3 continuous variables, was equal for the 3 groups. M had more corneal scarring than did HA or HI; however, there was no progression of scarring for any of the groups.

CONCLUSION

Keratoconus progressed in both men and women, aged 48-59 years; however, there were no differences among the groups in progression.