Prevalence Of Keratoconus Research Articles

Prevalence and topographical characteristics of keratoconus in patients with refractive errors in the Egyptian delta

To study the prevalence of keratoconus (KC) and the topographical characteristics of the affected corneas in patients with refractive errors who were seeking refractive surgery in the Egyptian delta. A retrospective study covering four and half years (Jan 2012-June 2016) where the topographical data of 8124 participants were obtained from the records of a refractive center in the Nile delta region, Egypt. The diagnosis of KC was based on the Holladay criteria in one or both eyes, using the Pentacam scans, whereas grading of KC was based on the Amsler-Krumeich classification. The prevalence of KC was 1.12% (91/8124 participants) with 95% confidence interval 0.91-1.3. Of all the affected cases, 5 cases (5.5%) had unilateral, and the other 86 cases (94.5%) had bilateral KC. The affected and unaffected subjects did not show any significant difference regarding gender. Sixty-eight (38.4%) eyes had stage 1 KC, 53 eyes (29.9%) had stage 2, 27 eyes (15.3%) had stage 3, and 29 eyes (16.4%) had stage 4 KC. It was most prevalent (1.2%) among cases with astigmatism (P < 0.001). Keratoconus was found in 1.12% of patients seeking refractive surgery, with no gender preference. Most cases had bilateral affection. Astigmatism was the most common refractive error to be associated with keratoconus.

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

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

High prevalence and familial aggregation of keratoconus in an Iranian rural population: a population-based study.

The objective of this study was to determine the prevalence of keratoconus and the potential effect of genetic and environmental factors on its prevalence in households living in rural areas of Iran in a large population-based study. The present cross-sectional study was performed in two Iranian rural populations. Two rural areas were randomly selected in the southwest and north of Iran. All individuals over one year of age were invited to participate in the study. The study population underwent a thorough eye examination, including visual acuity measurement, refraction, slit lamp biomicroscopy, and Scheimpflug imaging. The diagnosis of keratoconus was made based on Pentacam-specific criteria, tomographic maps, and clinical findings. After detecting keratoconus cases, its prevalence in the study population was reported as a percentage with a 95% confidence interval (CI). For familial aggregation analysis, the odds ratios of keratoconus and its more severe types were calculated in different family relationships (siblings, parents-offspring, spouses) using second order generalised estimating equation. Of the 3851 eligible individuals, 3314 subjects participated in the study. After applying the exclusion criteria, data from 2667 subjects was used in the analysis. The prevalence of keratoconus in the present population was 4% (95% CI: 3-4). The odds of keratoconus were significantly higher in males (OR = 2.30, p = 0.032). To investigate the familial aggregation of keratoconus, we only evaluated families from which at least two members participated in the study. So, 403 families (1452 participants) were evaluated. Our results showed a higher odds ratio for the sibling pairs compare to parent-offspring pairs and as reported, the odds ratio of the spouses was less than 1.0. Our findings showed a relatively high prevalence and familial aggregation of keratoconus in rural areas of Iran, independent of age, sex, and place of residence. This aggregation may be due to heredity or the effect of undetermined shared environmental factors.

Prevalence of keratoconus in paediatric patients in Riyadh, Saudi Arabia

Background/aimKeratoconus (KC) is a ectatic corneal disorder with marked progression during childhood and puberty that may lead to severe visual loss. In addition to KC prevalence, estimate shows major geographical...

Screening for keratoconus in a refractive surgery population of Upper Egypt

Purpose The purpose of this study was to evaluate the prevalence of keratoconus among candidates of refractive surgery in Upper Egypt. Setting The study was conducted in Sohag University Hospital and Future Center (a private center) for laser in-situ keratomiluesis and refractive surgery in Sohag Governorate, Egypt. Design This is an observational cross-sectional study. Patients and methods Refractive surgery candidates referred for preoperative evaluation before laser in-situ keratomiluesis, photorefractive keratectomy, and phakic intraocular lens implantation in the period from April 2015 to September 2015 were screened for keratoconus using Sirrus Scheimpflug camera. Results The study included 1202 patients, 623 male and 579 female. Keratoconus was detected in 210 (17.5%) patients. Conclusion Prevalence of keratoconus among refractive surgery candidates in Upper Egypt is relatively high, which may reflect an underlying high prevalence in the general population.

Prevalence of keratoconus among patients seeking laser vision correction in Taif area of Saudi Arabia

PurposeTo determine the prevalence of keratoconus among patients seeking laser vision correction (LVC). MethodsRetrospective study of 1374 eyes of 687 patients (335 males, 352 females) who underwent keratoconus screening as a part of routine preoperative evaluation prior to LVC at the Tadawi surgical centre, Taif, Saudi Arabia from January 2014 to June 2015. The diagnosis of keratoconus was based on evaluation of Pentacam derived parameters. ResultsManifest keratoconus was found in 59 subjects (out of 687 subjects) representing a prevalence rate of 8.59%. Of the 687 subjects, 45 subjects (6.55%) had bilateral manifest keratoconus (manifest keratoconus in both eyes or manifest keratoconus in one eyes and sub-clinical in contralateral eye) and remaining 14 patients (2.04%) had unilateral manifest keratoconus (with normal fellow eye). Sub-clinical keratoconus was diagnosed in 65 patients representing a prevalence rate of 9.46%. Of the 687 patients, 20 cases (2.91%) with subclinical keratoconus were bilateral and 45 (6.55%) were unilateral. Overall, 19.70% males (66/335) and 16.48% (58/352) females had either manifest or sub-clinical keratoconus, representing no statistically significant difference in the gender predisposition of the keratoconus disease process (Chi Square test; p = .277). ConclusionHigh prevalence of keratoconus was found among patients seeking LVC. Possible factors contributing to the high prevalence were recognized to be highly selective population (patients seeking LVC for myopia/hyperopia/astigmatism), ethnicity (high prevalence of consanguinity) and geographical location (high altitude) of the study subjects.

Therapeutic Options in Keratoconus

A recent epidemiology study revealed that prevalence of keratoconus was much higher than previously assumed. Therefore, it is no longer deemed an "orphan disease", as it has a relevant socioeconomic impact on the healthcare system. One of the most important risk factors for developing keratoconus is chronic eye rubbing which, apart from other known risk factors such as atopy or Down's syndrome, is the only modifiable factor. Informing the patient and offering behavior modifying therapies seems to be essential. Further therapeutic options regarding improvement of visual function include the wearing of glasses and the fitting of rigid gas permeable contact lenses and implantation of intrastromal corneal ring segments or phakic intraocular lenses. Corneal crosslinking (CXL) has been proven to be a highly effective and safe procedure in keratoconus cases showing disease progression. Significantly fewer corneal transplants were performed in this indication following the introduction of CXL. Recent studies reevaluated a combination of photorefractive keratectomy, which has been contraindicated until recently for patients with primary corneal ectasia with CXL, reporting a positive visual refractive outcome and stability of keratoconus. Still, penetrating keratoplasty is the gold standard of surgical treatment for end-stage keratoconus, whereas recently lamellar procedures have gained higher importance.

Is Keratoconus Really Rare?

The most used prevalence rate of keratoconus is 1:2,000, which defines the disease as rare. More recent studies suggest that the prevalence is significantly higher than 1:2,000. This increase in prevalence may be explained by the introduction of modern and highly sensitive corneal imaging technologies and a better understanding of geographical variations in the prevalence of keratoconus. The K-MAP study (NCT03115710) will determine the global prevalence of keratoconus in the young population and thus help support the introduction of screening initiatives for this not-so-rare disease.

Prevalence of Keratoconus in Refractive Surgery Population in Sohag Governorate

IntroductionKeratoconus (KC) is a developmental anomaly in which the inferior or central portion of the cornea becomes thinner and bulges forward in a cone-shaped fashion as a result of non-inflammatory thinning of the corneal stroma[1, 2]. The disease has its usual onset at puberty and, in many cases, progresses until the third to fourth decade of life, when it usually arrests[1]. Although a large proportion of keratoconic patients can be managed with contact lenses, an average of about 20% of all keratoconic corneas require keratoplasty; some authors report markedly different surgical indication rates of 6.5 and 12 to 45%.[3-5] Aim of the work: to study the prevalence of keratoconus in patients seeking refractive surgery to correct their refractive errors and to study common risk factors. Patients and Methods: Two thousand eyes to 1202 patients (623 males and 579 females) coming for investigations for refractive surgery were randomly chosen in the period from April to October 2015. Screening –by Pentacam- was bilateral in 798 patients and unilateral in 404 patients. Results: the resulting cases of keratoconus were 293 eyes (14.65%) of 210 patients. Of those patients, males were 117 (165 eyes) (56.25%) and females were 93 (128 eyes) (43.75%).

Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study

To determine the age-specific incidence and prevalence of keratoconus in the modern era of diagnostics. Epidemiologic study. Total of 4.4 million patients from a mandatory health insurance database. Data were extracted from the largest health insurance provider in the Netherlands. Patients aged 10-40 years were defined as the relevant age category for newly diagnosed keratoconus and the annual incidence of newly diagnosed keratoconus was determined. The prevalence of keratoconus was estimated based on the annual incidence, mean age at diagnosis, and average life expectancy. Main outcome measure was the annual incidence and prevalence of keratoconus. The annual incidence of keratoconus was 1:7500 in the relevant age category (13.3 cases per 100 000, 95% confidence interval [CI]: 11.6-15.2) and theestimated prevalence of keratoconus in the general population was 1:375 (265 cases per 100 000, 95% CI: 260-270). These values are 5-fold to 10-fold higher than previously reported values in population studies. The mean age at diagnosis was 28.3 years and 60.6% of diagnosed patients were male. Both the annual incidence and the prevalence of keratoconus were 5-fold to 10-fold higher than previously reported.

Very Low Prevalence of Keratoconus in a Large Series of Vernal Keratoconjunctivitis Patients

To evaluate the prevalence of keratoconus (KC) and other corneal abnormalities by means of videokeratography and tomography in a large series of patients affected by vernal keratoconjunctivitis (VKC). Cross-sectional study. Setting: Single-center children's hospital. A total of 651 consecutive patients with VKC and a control group of 500 were prospectively recruited between May 1, 2012 and September 30, 2013, with a minimum follow-up of 12months. All patients were evaluated by means of a Scheimpflug camera combined with a Placido corneal topographer. Keratoconus, suspected keratoconus, or its absence were determined in each patient. The corneal symmetry index of front (SIf) and back curvature (SIb), shape indices, and thicknesses were compared between the 2 groups. Prevalence of keratoconus and corneal indices modifications. Five out of 651 patients (0.77%) demonstrated topographic signs of KC. Two of them were bilateral. All patients were older than 7 years of age, and the mean age was 11.54 years. Four other patients (0.61%) were classified as KC suspects by the screening program. Of 304 patients older than 11 years (mean age 14.4 years), 4 (1.32%) were found to have KCN, and 4 (1.32%) were KC suspects. The corneal indices of patients in the VKC group were extremely similar to those in the control group. (P > .05). The prevalence of KC in our patient population, compared with previous reports in the literature, is much lower. The similar corneal indices in both groups suggest the absence of permanent corneal deformation due to VKC.

Association Between Keratoconus and Familial Mediterranean Fever in Turkey.

To evaluate the association between familial Mediterranean fever (FMF) and keratoconus (KC). This retrospective case-control study was performed to compare the prevalence of KC in patients with FMF with the corresponding prevalence in control patients without FMF referred to Genetic Diagnostic Center at Diskapi Yildirim Beyazit Training and Research Hospital from June 2012 to June 2015. We included all 100 patients with FMF. Each FMF-affected patient was matched to 3 controls. None of the patients in the control group (0%, 0/300) had KC, whereas 4 of 100 patients with FMF (4%) had KC (P < 0.004). Three of 33 patients with a homozygous mutation (9.1%) (M694V/M694V in 2 cases and M680I/M680I in 1 case) and 1 of the 46 patients with a compound heterozygous mutation (2.2%) (M694V/M680I) had KC, whereas none of the 21 patients with a heterozygous mutation (0%) had KC. All patients with KC were women, and mean age was 40.8 years (range, 30-51). Although 1 of the 4 patients with KC had hypertension and type 2 diabetes mellitus, the other 3 patients did not have any systemic illness except FMF. When we compared the prevalence of KC in patients with FMF (4%) with the highest prevalence of KC reported in the literature (0.2%), FMF was a predisposing factor to develop KC [odds ratio: 18.1 (95% CI: 11.9-27.5)] especially in patients with a homozygous mutation [odds ratio: 43.4 (95% CI: 28.6-65.7)]. Mediterranean fever (MEFV) gene mutations, particularly in homozygous mutations of the MEFV gene, may be a predisposing factor in the development of KC.

Eye Rubbing, a Sine Qua Non for Keratoconus?

ABSTRACT Keratoconus, a dystrophy of unknown origin, remains an ophthalmic enigma. The contrast between the presence of marked structural changes and deformation of the corneal wall and the relative absence of specific genetic and biomolecular findings continues to intrigue ophthalmologists. In Marfan syndrome, where genetic and molecular abnormalities are well identified, and similar changes in collagen observed, the cornea tends not to be steeper, irregular or ectatic, but are globally flatter. This suggests that an external mechanical force may be necessary to induce the apparition and progression of the ectatic process in keratoconus. Eye rubbing has long been acknowledged as a risk factor for keratoconus and its progression, but could it in fact be the root cause? Many clinical observations and reports support the hypothesis of eye rubbing as a first and necessary hit for inducing progressive ectatic deformation of the corneal wall. Validating or refuting this hypothesis on the basis of patient admission may be impossible. It is difficult to document the frequency, duration and intensity of eye rubbing in patients with keratoconus, and virtually impossible to prove that every patient who denies the habit truly does not rub his eyes. Both the increase in incidence of atopy and the time spent in front of the computer screen in the general population may account for an increased tendency for eye rubbing, and lead to the perceived increased prevalence of keratoconus in both urban and non-urban areas. This paper explores the possibility that the mechanical stress imposed on the cornea by rubbing may not be as much a second hit evoking the structural changes of a predisposed cornea exhibiting unknown collagen progressive alteration, but rather the necessary trigger and sine qua non of the keratoconic process. Even if this provocative hypothesis is impossible to prove, it is equally difficult to refute, and acknowledging eye rubbing as a possible root cause increases awareness within the general population and if true, could dramatically reduce the incidence of keratoconus, and halt its progression in eyes already affected. How to cite this article Gatinel D. Eye Rubbing, a Sine Qua Non for Keratoconus? Int J Kerat Ect Cor Dis 2016;5(1):6-12.

Skin Biophysical Characteristics in Patients with Keratoconus: A Controlled Study

Background. Keratoconus is a relatively common corneal disease causing significant visual disability. Individuals with connective tissue disorders that affect the skin such as Marfan's syndrome and Ehlers-Danlos syndrome or patients with atopic dermatitis show an increased prevalence of keratoconus. It seems that there are some concurrent alterations of skin and cornea in patients with keratoconus. Objective. We plan to compare skin biophysical characteristics in patients with keratoconus and healthy controls. Methods. Forty patients with keratoconus (18 females and 22 males) with mean (SD) age of 33.32 (9.55) years (range 19–56) and 40 healthy controls were recruited to this study. Skin biophysical characteristics including cutaneous resonance running time (CRRT), stratum corneum hydration, and melanin values were measured in patients and controls. Results. The median CRRT, stratum corneum hydration, and melanin measurements were significantly lower in patients with keratoconus in comparison with healthy controls. Conclusion. There are some alterations of skin biophysical properties in patients with keratoconus. Therefore, the assessment of these skin parameters could provide us some clues to the possible common biophysical variations of cornea and skin tissue in diseases such as keratoconus.

Prevalence of Keratoconus Among a Palestinian Tertiary Student Population.

Purpose:To screen for keratoconus and potential associated risk factors in a tertiary student population sample.Population and Methods:This cross sectional study included 1234 students attending An-Najah National University (Nablus, West Bank, Palestine), that were randomly selected from a total of 20,000 university students. 634 (51.3%) student participants responded by completing a self-administered questionnaire and were assessed by means of corneal topography. Following initial evaluation, participants were referred for Pentacam evaluation if they demonstrated either a mean keratometry of more than 45 diopters, corneal astigmatism of more than 2 diopters and/or if asymmetric topographic patterns were present. Pentacam images were analyzed by an experienced ophthalmologist based on a number of indices and the participants were classified as normal, keratoconus suspects, and keratoconus patients.Results:A total of 620 participants (mean age, 20.1±1.6 years) were included in this study, 379 (61.1%) were females and 241 (38.9%) were males. Nine subjects were diagnosed with keratoconus, demonstrating a prevalence of 1.5%. 52 (8.4%) participants showed at least one abnormal pentacam index, and were considered as KC suspects.Conclusion:Keratoconus is a prevalent disease among the tertiary Palestinian student population. This may be related to a combination of genetic and environmental factors. The results of this study signal the need for public health outreach and intervention for keratoconus.

Keratoconus in Inflammatory Bowel Disease Patients: A Cross-sectional Study

Increasing evidence suggests that keratoconus may have an inflammatory component. The possible association of keratoconus with inflammatory bowel disease (IBD) has yet to be determined. The aim of this study was to determine the prevalence of keratoconus and suspect keratoconus in patients with IBD. All consecutive adult IBD patients seen in the Department of Gastroenterology, Nancy, University Hospital, France, between March 2014 and June 2014 were included. Pregnant women, rigid lens wearers, patients with a family history of keratoconus and patients with a history of refractive surgery were excluded. A control group of healthy subjects was included. All included patients underwent a corneal topography (OPD-Scan III, Nidek) to detect keratoconus or suspect keratoconus. Rabinowitz videokeratographic indices were the basis of corneal topography interpretation. Two hundred and one IBD patients were included, 150 with Crohn's disease and 51 with ulcerative colitis. Mean age was 38.7 years and 121 were women. Mean disease duration was 10.8 years. Two IBD patients were diagnosed with keratoconus (1%) and 38 with suspect keratoconus (18.9%). Overall prevalence of keratoconus and suspect keratoconus was 19.9% (95% confidence interval [CI] 17.5-22.0). None of the 100 healthy subjects had keratoconus, while three were diagnosed with suspect keratoconus (p = 0.0002 versus IBD patients). Only smoking was identified as a risk factor (p = 0.029), especially in Crohn's disease. Inflammatory bowel disease patients may carry an increased risk of keratoconus and suspect keratoconus, smoking further increasing this risk. This supports the hypothesis of an inflammatory origin of keratoconus.

Keratoconus: tissue engineering and biomaterials.

Keratoconus (KC) is a bilateral, asymmetric, corneal disorder that is characterized by progressive thinning, steepening, and potential scarring. The prevalence of KC is stated to be 1 in 2000 persons worldwide; however, numbers vary depending on size of the study and regions. KC appears more often in South Asian, Eastern Mediterranean, and North African populations. The cause remains unknown, although a variety of factors have been considered. Genetics, cellular, and mechanical changes have all been reported; however, most of these studies have proven inconclusive. Clearly, the major problem here, like with any other ocular disease, is quality of life and the threat of vision loss. While most KC cases progress until the third or fourth decade, it varies between individuals. Patients may experience periods of several months with significant changes followed by months or years of no change, followed by another period of rapid changes. Despite the major advancements, it is still uncertain how to treat KC at early stages and prevent vision impairment. There are currently limited tissue engineering techniques and/or “smart” biomaterials that can help arrest the progression of KC. This review will focus on current treatments and how biomaterials may hold promise for the future.

The prevalence of keratoconus in a young population in Mashhad, Iran.

To determine the prevalence of keratoconus and some associated factors in the students of Mashhad University of Medical Sciences, Iran. In this cross sectional study, multistage cluster sampling was used to select the participants. All participants underwent retinoscopy, slit lamp examination, topography with the TMS-4 and corneal assessment with the Orbscan II. The diagnosis of keratoconus was based on both clinical evidence and the results of corneal imaging. Of 1280 selected students, 1073 agreed to participate in the study, and of those who agreed, 1027 fulfilled the inclusion criteria. 42.5% of the study population was male with a mean age of 26.1±2.3years. The prevalence of keratoconus was 2.5% (n=26) (95% confidence interval, CI 1.6-3.5). Eighteen students (69%) had bilateral keratoconus. Imaging of the cornea revealed that 70% of the keratoconics had nipple cones and the remaining had asymmetric bow-tie patterns. The prevalence of keratoconus was not significantly associated with age or gender (p>0.05). In a multiple logistic regression model, family history (OR=11.4, 95% CI: 2.5-51.3) and eye rubbing (OR=6.3, 95% CI: 1.6-24.3) were significantly correlated with keratoconus. These results taken together with recent studies in the area suggest that keratoconus may have a higher prevalence in the Middle East and Asia than in Western Countries.

Prevalence of keratoconus in an adolescent population

IntroductionKeratoconus is an idiopathic and progressive disease, where the cornea develops an irregular and conical shape, being the most common form of dystrophy or corneal ectasia, developing between the age of 12 and 20. In Mexico, the epidemiological information about the pathology is scarce. PurposeTo explore the epidemiology of keratoconus in Mexico among adolescents, and to compare the prevalence with international literature reports. This study identified associated pathologies and examined the management of patients. MethodsA retrospective study was conducted in an ophthalmology clinic; 500 charts were randomly selected from patients between 10 and 20 years of age in order to acquire information about the identification of the patient; the patient's gender, birthday, and age; three principal diagnoses at the first visit; as well as refraction and visual acuity in both eyes. After this, statistical analysis of the information was done. ResultsThe prevalence rate of keratoconus was 1.8%, affecting 66% of females and 33.3% of males. The mean age of presentation was 16.1 years. The most frequently associated refractive error was compound myopic astigmatism (44.4%); 88.8% presented with bilateralism. The majority of patients were being managed conservatively. ConclusionThrough this study, we found that our statistics matched those of internationally published reports concerning the early age of onset of the disease and its corresponding bilateralism. However, contrary to the international reports, it was evident that this condition was more prevalent among the females in our study sample, and no other associated pathologies were found.

Prevalence of Keratoconus among Young Arab students in Israel

ABSTRACT Purpose To determine the prevalence of keratoconus (KC) in an Arab population in Israel. Materials and methods Videokeratography was performed on volunteer students from the Academic Arab College of Education, in Haifa, Israel. All participants filled out a self-administered questionnaire to evaluate possible risk factors for KC. Univariate and multivariate analysis were performed. Results Data of 314 participants were analyzed and a prevalence of (N = 10), 3.18% (95% CI, 1.2 to 5.1%) was found. The only significant factor (both in univariate and multivariate analysis) that was associated with KC was parental consanguinity (OR 5.10, p = 0.02). Druzes and Bedouins had a higher prevalence than Muslims and Christians. However, the differences were not significant possibly due to the small size of the sample. Conclusion The result of this study was similar to other studies conducted in the Middle East, which indicate a higher prevalence of KC than in western countries. It is also recommended that people who have consanguinity in their family should be topographically tested to detect the early stages of KC. How to cite this article Shneor E, Millodot M, Gordon-Shaag A, Essa M, Anton M, Barbara R, Barbara A. Prevalence of Keratoconus among Young Arab Students in Israel. Int J Kerat Ect Cor Dis 2014;3(1):9-14.