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Keratoconus is a progressive blinding eye disease that characterized by corneal thinning and protrusion, which accompanied with irregular astigmatism and impaired visual acuity.The irregular astigmatism of early keratoconus can be corrected by spectacles. For the irregular astigmatism of moderate to severe keratoconus, spectacles are no longer suitable, and contact lenses are the best choice for patients to restore vision. There are various types of contact lenses, making the selection very difficult. In addition, trying on lenses for a long time will increase the discomfort and overall feeling of patients, and greatly increase the workload of doctors. Thus, the article aims to summarize and discuss the classification of contact lenses, the application of contact lenses in different types of keratoconus, the complications of contact lens, and the current status and prospect of contact lenses, with a view to understanding the management and clinical application of contact lenses in keratoconus patients and to further improving the application value of contact lenses in keratoconus.
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Objective:To investigate the clinical characteristics of patients with keratoconus, and to explore the factors influencing keratoconus severity.Methods:A cross-sectional study was performed.A total of 908 patients (1 476 eyes) with primary keratoconus were enrolled in Henan Eye Hospital from January 2019 to December 2021.The medical history data of patients were collected by face-to-face questionnaire survey.Refractive parameters were measured by subjective optometry.Intraocular pressure (IOP) was measured by a non-contact tonometer, and corrected IOP was calculated by Dresden formula.Corneal topography parameters was obtained using Pentacam HR.The subgroup analysis of clinical characteristics of all patients was performed by age (<21 years, 21~<31 years, ≥31 years) and gender.Disease severity was graded based on steep keratometry (Ks), namely mild (Ks<48 D), moderate (48 D≤Ks<55 D) and severe (Ks≥55 D). The influencing factors of disease severity in keratoconus were analyzed by ordered Logistic regression.This study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of Henan Eye Hospital (No.HNEECKY-2019[5]). All subjects or guardians were informed of the purpose and significance of the study and written informed consent was obtained.Results:Of the 908 patients, 622 were with bilateral keratoconus and 286 were with unilateral keratoconus.The median age of onset was 20(17, 26) years, and the median age of diagnosis was 21(18, 27) years.The ratio of males to females was 3.05∶1.There were 9.80%(89/908) of the patients having a history of allergy, 25.55%(232/908) having a history of other systemic diseases, and 1.98%(18/908) having a family history of keratoconus.Of the 1 476 affected eyes, 27.57%(407/1 476) were diagnosed as severe keratoconus, and 61.94%(568/917) had a history of eye rubbing.The medians of sphericity, cylindricity, IOP, corrected IOP, Ks, thinnest corneal thickness (TCT), anterior corneal surface elevation (AE) and posterior corneal surface elevation (PE) were -4.00(-7.00, -1.75)D, -3.50(-6.00, -1.50)D, 12.00(10.30, 13.80)mmHg, 15.40(13.60, 17.00)mmHg, 49.85(46.40, 54.90)D, 460.00(425.00, 490.00)μm, 21.00(13.00, 34.75)μm, 51.00(33.00, 75.00)μm, respectively.The spherical refraction, IOP and corrected IOP were lower and the cylindrical refraction was higher in patients at age <21 years than in patients at age 21~<31 years, and the TCT of patients at age <21 years was higher than that at age ≥31 years, and the differences were statistically significant (all at P<0.05). Compared with female patients, male patients had younger onset age, lower spherical refraction, IOP and corrected IOP, as well as higher cylindrical refraction, AE and PE, showing statistically significant differences (all at P<0.05). The spherical refraction and IOP of male patients were lower than those of female patients at age <21 years, and the cylindrical refraction was higher in males than in females among the patients at age 21~<31 years, and the differences were statistically significant (both at P<0.05). Among the patients with onset age <21 years and diagnosis age <21 years, the ratio of males to females in patients with severe keratoconus was higher than those with mild and moderate disease, and the difference was statistically significant (both at P<0.05). Older age of onset was a protective factor for disease severity in keratoconus (odds ratio=0.981, 95% confidence interval: 0.963~0.999). Conclusions:The younger the onset age of keratoconus patients, the more severe the disease.Among the patients with severe keratoconus, there were more male patients, and males have a younger onset age and severer conditions.It is suggested that early screening of keratoconus in children and adolescents should be strengthened in clinical work, and more active prevention and treatment measures should be taken for younger patients, especially males.
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Corneal densitometry is a biological property of corneal tissue, which is related to the transparency of cornea, and can be used to describe the degree of corneal transparency.At present, corneal densitometry has been used in the auxiliary diagnosis and severity evaluation of corneal diseases, as well as in the evaluation of the surgical outcome and the postoperative follow-up, even some systemic diseases affecting the cornea.The measurement of corneal densitometry is an objective, non-invasive and repeatable method to evaluate corneal transparency, which has important reference values for the monitoring of corneal and systemic health.In this article, the application of corneal densitometry in clinical practices was reviewed.
ABSTRACT
Keratoconus is a progressive and bilateral corneal disease with the characteristics of the protrusion of the dilated and central thinning cornea.Keratoconus often causes myopia and irregular astigmatism, and corneal edema and scarring in the late stage, leads to significant vision loss, and brings patients psychological pressure and economic burden.Eye rubbing is an important risk factor of keratoconus.Many studies suggest that eye rubbing is related to the occurrence and development of keratoconus.Different frequency and intensity of eye rubbing have different effects on the cornea.In susceptible population, eye rubbing causes severer damage to the cornea and more serious consequences.Eye rubbing damages the cornea by direct mechanical action, raising corneal temperature and intraocular pressure and releasing inflammatory factors resulting in cell apoptosis.Avoiding eye rubbing is of great significance in delaying the development of keratoconus.Reducing the rubbing time and frequency of patients with keratoconus by treating the primary disease causing eye rubbing and distracting them can reduce the occurrence and slow down the progression of keratoconus, and the life quality of patients can be improved.In this review, the role of eye rubbing in the etiology of keratoconus was elucidated to provide reference for the treatment and prevention of keratoconus.
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Keratoconus is a corneal ectasia disease characterized by conical protrusion, progressive corneal thinning and irregular astigmatism.The etiology of keratoconus remains unclear now.Multiple factors contribute to the disease.A large number of studies have shown that the occurrence of keratoconus is closely related to heredity, and there exists obvious genetic heterogeneity.The incidence of keratoconus in patients with allergic diseases and frequent eye rubbing is high.Ultraviolet irradiation can damage the ocular surface and induce keratoconus subsequently.Keratectasia is a serious complication after refractive surgery.In this article, the risk factors including genetic susceptibility, eye rubbing, allergic diseases, ultraviolet irradiation, refractive surgery that related to keratoconus are reviewed.
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Objective@#To evaluate the repeatability of corneal biomechanics parameters measured by Corneal Visualization Scheimpflug Technology (Corvis ST) and explore the factors that influence the repeatability.@*Methods@#A diagnostic test study was performed.A total of 190 eyes in 95 myopia patients (34 males and 61 females) were enrolled from September to October 2017 in Henan Eye Hospital.All the subjects underwent 5 repeated examinations with the Corvis ST.The intraclass correlation coefficient (ICC), Cronbach α coefficients and repeatability coefficient (RC) were computed to evaluate repeatability of Corvis ST parameters.The multiple linear regression analysis was used to study the factors that affect the magnitude of the test-retest variability (within subject SD) of new Corvis ST parameters.This study was approved by the Ethics Committee of Henan Eye Hospital (HNEECKY-2019[5]), and written informed consent was obtained from each subject.@*Results@#Among the 39 biomechanics parameters, The ICC and Cronbach α were greater than 0.75 for 26 parameters, within 0.60-0.75 for 4 parameters, and lower than 0.60 for deflection amplitude max time (DLAMT). The ICC and Cronbach α of DA ratio max[1 mm], DA ratio max [2 mm], max inverse radius, Ambrósio's relational thickness horizontal (ARTh), biomechanical intraocular pressure (bIOP), integrated radius, stiffness parameter applanation 1 (SPA1) and Corvis biomechanical index (CBI)were all above 0.920.The multivariate regression results indicated that the within subject SD of bIOP increased with the increase of IOP (β=0.210, P=0.010). The within subjects SD of DA Ratio Max [1 mm]decreased with the increase of central corneal thickness (CCT) (β=-0.218, P=0.008). The within subjects SD of DA Ratio Max [2 mm]decreased with the increase of CCT(β=-0.295, P<0.001). The within subject SD of CBI decreased with the increase of astigmatism, axial lengths and CCT (β=-0.190、-0.148、-0.428, all P<0.05).@*Conclusion@#The Corvis ST parameters showed favorable measurement repeatability in myopia patients, especially for the new parameters.Astigmatism, axial lengths and CCT significantly affected the repeatability of CBI.
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Objective To study the sensitivity and specificity of parameter Corvis biomechanical index (CBI)— a new biomechanical index of Corvis ST in the diagnosis of keratoconus and evaluate the role of CBI in the diagnosis of keratoconus and the change of biomechanic.Methods A diagnostic trial study was adopted,and 66 eyes from 49 keratoconic patients (keratoconus group) and 91 right eyes from 91 myopic patients (control group) from April in 2018 to August in 2018 in Henan Eye Hospital were enrolled.Pentacam and Corvis ST examinations were performed by the same operator after the basic eye examinations.Using the evaluation of diagnostic test,consistency test,and receiver operating characteristic (ROC) curve analysis,gain the outcome of the sensitivity,specificity,consistency,Youden index,and area under the ROC curve of the parameter CBI.This study protocol was approved by Ethic Committee of Henan Eye Hospital and followed the Declaration of Helsinki.Written informed consent was obtained from each patient prior to any medical examination.Results Sixty eyes were diagnosed as keratoconus by the parameter CBI of Corvis ST.Evaluation of diagnosis test:the sensitivity was 97.0％,and the specificity was 97.8％;consistency check:Kappa =0.948,P＜0.05.ROC curve analysis:the sensitivity was 98.5％,the specificity was 96.8％,Youden index was 96.3％,P＜0.000 1 and AUC was 0.996.Conclusions CBI can separate healthy eyes from keratoconic eyes with highly sensitivity and specificity,which was highly consistency with results of Rabinowitz keratoconus diagnostic criteria.CBI could be used as a new biomechanical indicator for the diagnosis of keratoconus.
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Background Researches showed that femtosecond laser corneal small incision lenticule extraction (SMILE) was used in the correction of myopia and myopic astigmatism due to its fast recovery,good shortterm efficacy and few complications.However,few research focused on its long-term efficacy.Objective Thisstudy was to evaluate the effectiveness,safety,predictability,stability and complications of SMILE.Methods A serial cases-observational study was carried out under the approval of Ethic Committee of Henan Eye Institute and informed consent of patients.Sixty-seven eyes of 34 patients with myopia and myopic astigmatism were included in Henan Eye Institute from January to June 2013.All the patients received SMILE and followed-up for 2-year duration.The uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),automatic optometry,intraocular pressure and corneal topography were examined before surgery and 1 day,1 week,1 month,3 months,1 year and 2 years after surgery and calculated the spherical equivalent (SE).The long-term efficacy of SMILE included effective index (preoperative BCVA/postoperative UCVA),safety index (postoperative BCVA/ preoperative BCVA),predictability (linear regression analysis between actual SE and attempted SE) and refractive stability (SE changes at postoperative time points).Results The preoperative BCVA was ≥ 20/20 in 60 eyes with the percentage of 89.55％.UCVA≥ 20/20 were found in 61 eyes and 60 eyes in postoperative 3 months and 2 years respectively (91.04％ and 89.55％).The effective index was 1.038±0.182 and 1.029±0.231 in postoperative 3 months and 2 years respectively,showing an insignificant difference between them (t =0.400,P ＞ 0.05).Compared with the preoperative BCVA,8.96％ (6/67) and 10.45％ (7/67) eyes lost 1 line at 3 months and 2 years after surgery,respectively.The safety indexes were 1.141±0.193 and 1.312±0.242 at 3 months and 2 years after surgery,with no significant difference between them (t =0.414,P＞0.05).A linear correlation was found between actual SE and attempted SE both at postoperative 3 months and 2 years,with the linear regression equations of Y=0.897 1X-0.440 8 (R2 =0.914 2,P＜0.05) and Y =0.893 7X-0.382 3 (R2 =0.915 7,P＜0.05),respectively.The SE was (0.013±0.578),(-0.033±0.489),(-0.106±0.508),(-0.103±0.375),(-0.154±0.518) and (-0.147±0.366)D 1 day,1 week,1 month,3 months,1 year and 2 years after surgery,respectively,and there were no significant difference among different time points (F =0.185,P =0.176).Eighteen in the 67 eyes occurred opaque bubble layer after surgery.Diffuse lamellar keratitis appeared in 6 eyes and punctate keratitis was in 2 eyes.These complications were cured 1 month after administration of drugs.Conclusions SMILE is good in effectiveness,safety,predictability and refreactive stability and has fewer complications during 2-year following-up.