Incidence Of Keratoconus Research Articles

Распространенность кератоконуса и пограничных состояний по данным эпидемиологических исследований

Purpose. To study the prevalence of keratoconus and borderline conditions, as well as their association with ophthalmological parameters among the population of the Southern Urals in population-based studies. Material and methods. On the basis of the Ufa Eye Research Institute, population-based studies were conducted in three age groups: among children and adolescents of school age (6–17 years old) – 4,890 people, respondents 40+ years old and over 85 years old – 5,314 and 651, respectively. Standard and additional ophthalmological examinations were performed, as well as a retrospective analysis of keratotopograms of both eyes of the respondents. For statistical processing of the obtained results, the SPSS application software package was used, the significance criteria were applied: χ², Student’s t-test and Fisher’s criterion (F-test) of variance analysis. Results. The results of the analysis of population studies data showed that the incidence of keratoconus in different age groups of the population is 0.02%, among children and adolescents of school age, 0.07% – in respondents 40+, 0.15% – over 85 years old. Borderline conditions (steep cornea) are more common at the age of 85+ (6.45%), much less common in 40+ (2.11%) and even more rare in children and adolescents (0.09%). At the same time, the frequency of occurrence of borderline conditions correlated in children with a shorter axial length of the eye, and in adults with a shorter axial length, a higher index of myopic and cylindrical refraction, a smaller thickness and a larger volume of the cornea, and a larger thickness of the lens. Conclusion.In the group of children and adolescents, the prevalence of keratoconus was 0.02%, in respondents 40+ – 0.07%, over 85 years of age – 0.15%. The prevalence of borderline conditions (steep cornea) increased with age – from 0.09% to 2.11% and 6.45%, respectively. Key words:keratoconus, prevalence, borderline conditions, population-based studies

Topographic Keratoconus Incidence in Greece Diagnosed in Routine Consecutive Cataract Procedures: A Consecutive Case Series of 1250 Cases over 5 Years.

Background: Scheimpflug tomography has for many years been an integral part of our pre-operative assessment in cataract extraction. We retrospectively reviewed the incidence of topographic keratoconus and keratoconus suspicion in our routine cataract surgery population over 5 years. Setting: The Laservision Clinical and Research Institute, Athens, Greece. Methods: In 1250 consecutive cataract surgery cases in otherwise naïve eyes, accounting for years 2017 to 2021, we retrospectively evaluated preoperative Pentacam HR imaging. The cases already classified as keratoconus were included in group A. The residual cases were assessed by five different experienced evaluators (two ophthalmic surgeons and three optometrists) for topographic and tomographic keratoconus suspicion based on irregular pachymetry distribution, astigmatism truncation, and/or astigmatic imaging irregularity and included in group B. Regular corneas, by this assessment, were included in group C; irregular corneas, as determined by the evaluators but unrelated to keratoconus, were included in group D. Results: Based on the above, 138 cases (11.08%) were classified by Pentacam tomography as keratoconus and by default were included in group A. Of the residual cases, 314 or 25.12% were classified as suspect keratoconus and included in group B; 725 cases (58%) were classified as normal and non-keratoconus and included in group C; and 73 cases or 5.84% were placed in group D as non-keratoconus but abnormal. There was no disagreement between the five evaluators over any of the cases in groups C and D, and little variance among them for cases included in group B (less than 5% by ANOVA). Conclusions: The incidence of keratoconus and corneas suspicious for keratoconus in Greece appears to be much higher than respective reports from other regions: one in ten Greeks appear to have topographic keratoconus, most not diagnosed even by the age of cataract surgery, and almost an additional one in four may have suspicious corneal imaging for keratoconus. These data strongly imply that routine screening for disease should be promoted among Greeks, especially during puberty, to halt possible progression; moreover, careful screening should be performed when laser vision correction is being considered.

Incidence and prevalence of keratoconus in Taiwan during 2000-2018 and their association with the use of corneal topography and tomography.

The aim of this study was to determine the age- and sex-specific incidence and prevalence of keratoconus (KC) in Taiwan and explore their association with the use of computerized corneal topography and tomography (TG). This nationwide retrospective study included the Taiwanese population (N = 27,540,859) from the National Health Insurance Research Database (NHIRD) between 2000 and 2018. We estimated the incidence of KC by identifying patients with newly diagnosed KC and estimated its prevalence by identifying patients who had the ICD9-CM code 371.6 or ICD-10-CM code H18.609 twice or more in NHIRD during 2000-2018. The incidence of KC in Taiwan during 2000-2018 was 7075, with the incidence rate being 1.56 (95% confidence interval [CI]: 1.53-1.60) per 100,000 person-years. The prevalence of KC was 4.29 (95% CI: 4.23-4.35) per 100,000 person-years. The KC incidence rate peaked in patients aged 21-25 (6.40 in males and 3.19 in females). The overall incidence rates in males and females were 2.01 and 1.35, respectively (incidence rate ratio: 1.46), indicating that KC had a significant male predisposition. Moreover, we noted a linear correlation (R2 = 0.7488) between the proportion of the use of TG and the incidence of KC. Estimates of nationwide population-based incidence and prevalence can contribute to a better understanding of the risk of ethnic groups and geographic locations in KC, and the trend can help physicians improve the general vision health of the population.

The Underlying Relationship between Keratoconus and Down Syndrome.

Keratoconus (KC) is one of the most significant corneal disorders worldwide, characterized by the progressive thinning and cone-shaped protrusion of the cornea, which can lead to severe visual impairment. The prevalence of KC varies greatly by ethnic groups and geographic regions and has been observed to be higher in recent years. Although studies reveal a possible link between KC and genetics, hormonal disturbances, environmental factors, and specific comorbidities such as Down Syndrome (DS), the exact cause of KC remains unknown. The incidence of KC ranges from 0% to 71% in DS patients, implying that as the worldwide population of DS patients grows, the number of KC patients may continue to rise significantly. As a result, this review aims to shed more light on the underlying relationship between KC and DS by examining the genetics relating to the cornea, central corneal thickness (CCT), and mechanical forces on the cornea, such as vigorous eye rubbing. Furthermore, this review discusses KC diagnostic and treatment strategies that may help detect KC in DS patients, as well as the available DS mouse models that could be used in modeling KC in DS patients. In summary, this review will provide improved clinical knowledge of KC in DS patients and promote additional KC-related research in these patients to enhance their eyesight and provide suitable treatment targets.

This issue of ACTA

This issue of ACTA

Pediatric Keratoconus in A Tertiary Eye Center in Alexandria: A Cross-sectional Study

ABSTRACT PURPOSE To describe the clinical presentation, risk factors, and treatment choices documented in a pediatric keratoconus population treated at a tertiary referral center in Alexandria, Egypt. METHODS : A cross-sectional study of 80 patients with keratoconus aged 18 years or younger referred to the cornea clinic at the Alexandria University Main Hospital between July 2018 and October 2019 was included. Patients’ history, initial presentation, best spectacle corrected visual acuity (BSCVA), clinical signs, topographic data, and treatment were recorded. RESULTS Thirty patients were younger than 14 years and 50 were 14 years or older. Elements of the initial presentation included decreased vision in 26 patients, itching in 20 patients, both visual impairment and itching in 16 patients, accidental discovery during vision screening at school in 15 patients, and hydrops in three patients. All patients had bilateral keratoconus, except for four patients who had previously been treated by keratoplasty (n = 156 eyes). The mean logMAR BSCVA was 0.79 ± 0.63. The mean of the average keratometry (AveK), maximum keratometry (Kmax), central corneal thickness (CCT) and thinnest pachymetry reading were 51.16 ± 7.31 D, 59.18 ± 10.38 D, 458.44 ± 55.87 µ 440.08 ± 60.18 µ, respectively. 57 eyes (36%) had stage 1 disease, 43 eyes (28%) had stage 2 disease, 17 eyes (11%) had stage 3 disease and 39 eyes (25%) had stage 4 disease, respectively. No statistically significant differences in the LogMAR BSCVA, keratometry values, CCT, thinnest pachymetry reading, and the Amsler-Krumeich (AK) staging existed between the two age groups or between boys and girls. Crosslinking was indicated in 69 eyes (44%), while keratoplasty was the only viable solution for 39 eyes (25%), with three patients requiring keratoplasty in both eyes. CONCLUSION Keratoconus in children can result in severe loss of vision. Keratoconus screening programs in elementary schools should be considered in populations with a high incidence of keratoconus for early detection and adequate intervention.

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

To estimate the national prevalence and incidence of keratoconus in Norway. 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 40years of age in the period 2010-2018. Data on age and gender of the keratoconus patients were also gathered. A total of 9832 keratoconus patients were registered. The estimated prevalence in the general population was 192.1 per 100000 (95% confidence interval (CI): 188.3-195.9), and the estimated annual incidence was 19.8 per 100000 (95% CI: 18.1-21.5). There was a predominance of males (73%), and mean age for all patients was 37.5years at first registration in this period. 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.

Incidence of Keratoconus in Refractive Surgery Population of Vojvodina - Single Center Study.

Introduction: Keratoconus (KCN) is known to affect all ethnicities but its incidence exhibits geographical variability plausibly due to subclinical forms of the disease, differences in diagnostic methods and criteria, or differences in genetic variations in populations.Aim:To examine the prevalence of keratoconus among the refractive surgery population of Vojvodina, who underwent refractive surgery screening at Eye Clinic Svjetlost Novi Sad, Serbia from September 2018 to September 2019. This is a single-center study.Methods:Retrospective analysis of 876 patients who presented for refractive surgery evaluation. Corneal tomographers represent the gold standard in the detection and classification of corneal ectatic diseases and screening is an essential part of the preoperative diagnostics before any refractive surgery. The corneal tomographer used in this study was a Scheimpflug imaging device (Pentacam AXL, Oculus Optikgeräte GmbH, Wetzlar, Germany). The device was realigned before each measurement.Results:Out of a total number of patients, 619 (70,7%) were candidates for corneal refractive surgery procedure, and 257 patients (29.3%) were not. Out of 257 patients that were not candidates for the procedure 157 (61,0%) patients had thin corneas, high myopia/hypermetropia or had some retinal disease; 75 patients (29,1) were keratoconus suspect and 25 patients (9,7%) had keratoconus. KCN patients had a mean age of 29.5 ± 7.7 years, 18 patients (72.0%) were male and 7 patients were female (28%).Conclusion:The most cited annual incidence of KCN is 2 approximately 1 per 2,000. Recent data from the biggest Netherland study revealed many different epidemiological results which deprive keratoconus of the community of rare diseases. The incidence of keratoconus in Vojvodina refractive surgery population presented in our Clinic was 2.9%.

Craniofacial fibrous dysplasia with ipsilateral keratoconus

Fibrous dysplasia (FD) is a developmental dysplastic disorder of the bone, in which the normal matrix is replaced by fibroblastic proliferation. Keratoconus is usually an isolated sporadic disorder which may be associated with various ocular and systemic conditions. We report a case of ipsilateral keratoconus with craniofacial FD. Only a single such case has been reported in literature. An 18-year-old male patient presented to us with right eye (RE) proptosis and protrusion of the forehead and lateral skull associated with poor vision in the RE. He had earlier undergone conservative excision and recontouring for FD. Best-corrected visual acuity in the RE was counting fingers at 1 m and in the left eye was 20/20. Clinical signs of keratoconus were present in the RE. Corneal topography confirmed the diagnosis of keratoconus. The incidence of keratoconus in this case may be an independent finding or may be related to pressure on the globe due to expanding orbital walls.

Keratoconus Screening Among Myopic Children.

AimTo assess the topographic corneal changes and the incidence of keratoconus among children with high myopia.SettingsIt is a prospective study, in which 174 eyes of children with high myopia were studied in the period between August 2015 and June 2018.MethodsAll patients were examined to assess the refractive error and corneal examination using Scheimpflug camera to evaluate different corneal parameters.ResultsStudied children aged between 6 and 14 years (11.05±1.98). Males represented 54% of the cases (n=94). The mean spherical error was −7.75±2.97 ranging from −6 to −13.50D. The mean cylindrical error was −4.12±1.78D (−1 to −8). Regarding corneal examination, data recorded were those about maximum K reading (kmax), thinnest location, highest anterior and posterior elevation in 4mm zone, and higher-order corneal aberrations. Analysis of the obtained data revealed 16 eyes (9.2%) with keratoconus. These eyes were considered as a separate group and compared with the remaining eyes. There was significant difference in kmax (p= 0.03), anterior elevation, and posterior elevation (p=0.01 for both). Regarding myopia or astigmatism, there were no significant differences when compared with normal eyes. But high myopia with low astigmatism were found in five eyes of them (31.2%). The main statistically different aberrations were vertical coma (−2.04±0.99) (p=0.01) and spherical aberrations (−0.9±0.78) (p=0.02). Regarding gender, there were 11 eyes in boys (68.7%), and this was statistically significant (p=0.01). Vernal keratoconjunctivitis with frequent eye rubbing was found in 6 eyes (37.5%).ConclusionChildren with high myopia irrespective of the degree of astigmatism may have corneal abnormalities which are more pronounced in cases with vernal keratoconjunctivitis. Corneal examination should be performed for highly myopic children to detect any corneal abnormality and to treat it as early as possible.

The incidence of keratoconus and its association with ocular disorders in Lahore population

Abstract This study was conducted to check predominance of keratoconus in male and female of the various age groups in Pakistan and to check the severity of disease in keratoconus patients. Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. A cross-sectional, analytical study was performed between September 2016 to May 2017 on Keratoconus patients visiting Layton Rahmatullah Benevolent Trust Hospital and Sir Ganga Ram Hospital during their ophthalmic consultation. The techniques used for the diagnosis of Keratoconus were Visual Acuity by Snellen chart, Ophthalmoscopy, Orbscan corneal topography, and Slit lamp bio microscopy. Total 110 patients of Keratoconus were studied in which 62 were females and 48 were males. Patients developed both unilateral as well as bilateral conditions. Visual acuity from normal to high vision loss was also observed in Keratoconus patients. Different disorders with different percentage such as Munson’s sign were present in 68 patients, Rizutti’s sign was present in 30 patients, Vogt’s striae were present in 26 patients and Fleischer ring was present in 23 patients. 19 patients had Atopic syndrome and 6 patients had Leber’s Congenital Amaurosis were also associated with keratoconus. Keywords: Cross-sectional; Keratoconus; Ophthalmoscopy; Orbscan corneal topography; Snellen chart; Slit lamp biomicroscopy http://dx.doi.org/10.19045/bspab.2019.80001

English

Keratoconus is a non inflammatory degenerative disease that compromises the structural integrity of the collagen matrix within the corneal stroma17. The hallmark characteristic is the development of a localized cone shaped ectasia that is accompanied by thinning of the stroma in the area of the cone. This leads to increasingly irregular astigmatism as well as a steeper corneal curvature. This causes retinal image blur and poor visual acuity. Keratoconus causes mild to severe loss of vision. The incidence of keratoconus in the general population is approximately 2 per 100,000 (0.002%)5. The prevalence rate of keratoconus is 54.5 per 100,000 (0.05%) It is a general rule that whatever test for keratoconus is performed in one eye it should always be done in the fellow eye and the results are compared. The incidence of keratoconus in the general population is approximately 2 per 100,000 (0.002%)5. The prevalence rate of keratoconus is 54.5 per 100,000 (0.05%) It is a general rule that whatever test for keratoconus is performed in one eye it should always be done in the fellow eye and the results are compared. CONCLUSION This study clearly demonstrates that the corneal topographic assessment of astigmatism shows higher values, which are not acceptable to the patients. Astigmatism correction with Automated Refractometry derived cylindrical values, were accepted well by the study group. This is probably because the cylindrical value assessed by corneal topography is confounded by the position of the cone with reference to the visual axis, whereas that obtained by AR is the one that is at the visual axis. This proves the usefulness of Automated Refractometry in astigmatism correction in keratoconus, even though Corneal Topography has the advantages of early detection of this condition. In centers where a video-keratoscope is not available, the AR machine can be used for visual rehabilitation.

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

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.

The Results of Corneal Hydrops Treatment in Patients with Down Syndrome

The article describes the clinical cases of acute keratoconus in three patients with Down syndrome who underwent penetrating keratoplasty. Acute keratoconus were diagnosed in patients by examination of medical history, biomicroscopy, corneal topography, optical coherence tomography. Acute keratoconus occurs suddenly due to the rupture of Descemet’s membrane in the zone of its stretching, when chamber moisture seeps into the thickness of the stroma, causing its swelling and perforation. If untreated, the process continues for 3–5 months. Most researchers recommend keratoplasty during the cold period of the disease. However, with the threat of perforation require urgent surgical intervention. There are two effective methods of surgical treatment: epikeratophakia and penetrating keratoplasty. Patients underwent penetrating keratoplasty. The preference for this method was given in connection with the following factors: young age patients (under 40 years), relatively healthy transparent peripheral zone of the cornea, which was observed in our patients, genetically determined diseases — Down syndrome, the threat of corneal perforation in the centre, a penchant for rubbing his eye, low vision other eye and the desire to obtain speedy optical effect along with the treatment. All patients after penetrating keratoplasty had improvement of visual acuity with observation periods up to 1 year. Due to the relatively high incidence of keratoconus in patients with Down syndrome should focus the attention of ophthalmologists. Thus, difficulties in the diagnosis of ophthalmic pathology in patients with concomitant Down syndrome can cause errors in verification of diagnosis and hence wrong treatment selection. In case of hydrops of the cornea penetrating keratoplasty is the choice treatment and contributes to the preservation of the eye and visual functions.

Pediatric Keratoconus in a Tertiary Referral Center: Incidence, Presentation, Risk Factors, and Treatment.

To report the incidence, clinical presentation, risk factors, and treatment outcome of pediatric keratoconus in a tertiary referral eye hospital in Beirut, Lebanon. In this retrospective study, the authors evaluated all patients with keratoconus 14 years or younger newly diagnosed at the Beirut Eye Specialist Hospital, Beirut, Lebanon, between January 2010 and December 2014. The incidence of pediatric keratoconus among all pediatric patients and among patients with keratoconus of all ages was assessed. Patients with pediatric keratoconus were evaluated for keratoconus stage, initial presentation, uncorrected distance visual acuity, corrected distance visual acuity (CDVA), corneal topography, and pachymetry. Patients were classified according to different treatment regimen groups and different follow-up visits were evaluated. During 5 years, 16,808 patients were examined, of whom 2,972 were 14 years or younger. A total of 541 patients were diagnosed as having keratoconus; of those, 16 were 14 years or younger at the time of diagnosis. Hence, the incidence of keratoconus was 0.53% among pediatric patients and 3.78% among adult patients (> 14 years). Initial presentation was during routine checkup (1 of 16) for allergic conjunctivitis (3 of 16), reduced vision (10 of 16), and corneal hydrops (mimicking keratitis) (2 of 16). Except for 2 patients lost to follow-up, all eyes received corneal cross-linking treatment and 16 eyes received additional intracorneal ring segment implantation. The incidence of pediatric keratoconus indicates that increased awareness for keratoconus among children is needed, mainly in cases of family history of keratoconus, ocular allergy/pruritus, poor CDVA, corneal hydrops, and/or high astigmatism. [J Refract Surg. 2016;32(8):534-541.].

Epidemiology of Keratoconus in an Iranian Population

To determine the incidence of clinical keratoconus (KCN) in an Iranian population. This prospective surveillance study was conducted in Yazd province in central Iran (population 990,818). During 1 year (July 2008 to June 2009), all new patients with KCN were registered and referred. Diagnosis was based on the topographic pattern, and indices were measured and eye examination was done by anterior segment subspecialists. Of the 564 eligible patients referred, 28 did not attend their topography session (95% response rate). Topographic figures showed suspect or definite patterns of KCN in 47.8% of participants (256/536 subjects). Based on topographic images and clinical examination, KCN was confirmed in 221 patients, and in addition, 26 patients were categorized as having suspected KCN and 9 had non-KCN corneal diseases; therefore, the annual incidence rate of KCN was estimated as 22.3 (95% confidence interval, 19.5-25.4) and 24.9 (95% confidence interval, 21.9-28.2) per 100,000 population, excluding and including suspected KCN cases, respectively. The incidence of KCN in our context is apparent and comparable with rates in other studies on Asian ethnic populations. This is much higher than the incidence in European Caucasians and warrants further genetic and environmental studies.

Prevalencija keratokonusa kod kandidata za refraktivne hirurške procedure

Introduction. Keratoconus is the most common primary ectasia and has a significant effect on visual acuity and the quality of life. The prevalence of keratoconus in the general population of Bosnia & Herzegovina, and Croatia remains unknown. This study was designed to show the incidence of keratoconus in candidates for Excimer laser refractive surgical procedures in our eye clinics. Methods. We analyzed preoperative examination data from 2,714 patients, collected over a two year period, who were candidates for Excimer refractive surgical procedures. Patients were sorted into groups according to their gender, age, degree of keratoconus (Amsler-Krumeich classification) and involvement of one or both eyes. Results. Keratoconus was detected in 231 patients (335 eyes); 133 of the patients were male and 99 were female. Unilateral keratoconus was found in 127, and bilateral in 104 patients. Four age groups were designated: 49 were 18 - 25 years old, 68 patients were 25 - 35 years old, and 57 were in both age groups, 36 - 45 and 45 -75 years. Keratoconus was diagnosed in 335 eyes with the following distribution: stage I - 86, stage II - 84, stage III - 97, and stage IV - 68 eyes. Conclusion. We examined a large number of patients preoperatively and found a higher prevalence of keratoconus than previously reported for the general population. Our particular sample does not accurately reflect the prevalence of the disorder within the general regional population of Bosnia & Herzegovina, and Croatia. Nonetheless, our findings signal a need for public health outreach and intervention for keratoconus within those regions.

Influence of ethnic origin on the incidence of keratoconus and associated atopic disease in Asians and white patients.

To investigate the influence of ethnic origin on the incidence of keratoconus and the association of atopic diseases in patients with keratoconus. Retrospective study of new patients referred to Dewsbury District General Hospital and diagnosed with keratoconus in a 6-year period between 1994 and 2000. The ethnic origin of the patient was defined as white, Asian, or other. Incidence was calculated from the catchment population of 176 774 (82% white people, 17% Asians, 1% others). t-Test, confidence intervals and chi2 tests were used to show statistical significance. A total of 74 cases of keratoconus were diagnosed over this period. Of these patients 29 (39%) were white and 45 (61%) were Asian. This equated to an incidence of keratoconus of 25 per 100 000 (1 in 4000) per year for Asians, compared with 3.3 per 100 000 (1 in 30 000) per year for white people (P<0.001). Asians presented significantly younger than white patients. The incidence of atopic disease was found to be significantly higher in white compared to Asian keratoconic patients. Asians were significantly more likely to present with keratoconus. The Asian patients were mostly of Northern Pakistani origin. This community has a tradition of consanguineous, especially first-cousin marriages. The higher incidence in this population was highly suggestive of a genetic factor being significant in the aetiology. The incidence was higher than revealed by previous studies. Atopic disease was significantly less common in Asians compared to white people, supporting the theory of a different aetiology in these patients.

Estimation of Patient Visit Rate and Incidence of Keratoconus in the 23 Wards of Tokyo

To estimate the patient visit rate and the incidence of keratoconus in the 23 Wards of Tokyo. We searched for keratoconus patients with questionnaires sent to 141 hospitals in the 23 Wards of Tokyo. The patient visit rate was estimated using the number of patients from 15 to 44 years old. The incidence was estimated from the number of patients in whom the onset of the disease was at the age 15 to 34. Three hundred and twenty-five patients (205 males and 120 females) were found during a survey of three months. The return rate of the questionnaires was 49.6%. Male/female ratio was 1.7/1.0. The patient visit rate of keratoconus during three months was estimated to be 12.4 x 10(-5) (1/8,100) in males and 6.7 x 10(-5) (1/15,000) in females. The annual incidence was estimated to be 12.1 x 10(-5) (1/8,300) in males and 5.6 x 10(-5) (1/17,900) in females. 6.5% of the patients were given corneal transplants. We estimated the patient visit rate and the incidence of keratoconus on the basis of the survey of hospitals of the 23 Wards of Tokyo during a 3-month period. Compared with the previous reports, our data suggests that the proportion of women is increasing in patients with keratoconus, and that the ratio of patients who have to receive corneal transplant therapy are decreasing. A large-scale epidemiological study is required.