scholarly journals Bilateral Differential Topography—A Novel Topographic Algorithm for Keratoconus and Ectatic Disease Screening

2021 ◽  
Vol 9 ◽  
Author(s):  
Yang Shen ◽  
Yiyong Xian ◽  
Tian Han ◽  
Xuanqi Wang ◽  
Xingtao Zhou
Keyword(s):  
Standard Deviation ◽  
Refractive Surgery ◽  
Anterior Segment ◽  
Roc Curves ◽  
Control Group ◽  
Corneal Ectasia ◽  
Scheimpflug Imaging ◽  
Diagnostic Models ◽  
Differential Characteristic ◽  
Corneal Refractive Surgery

Purpose: The purpose of this study was to establish a novel bilateral differential topographic algorithm and assess its efficacy for screening of keratoconus and corneal ectasia before corneal refractive surgery.Methods: One hundred and sixty-one consecutive patients (115 men and 46 women, aged 22.8 ± 6.8 years) with keratoconus, including clinical keratoconus, subclinical keratoconus, forme fruste keratoconus (FFK), and corneal ectasia (KC group) and one hundred and seventy-four consecutive patients (97 men and 77 women, aged 25.1 ± 6.7 years) with ametropia (control group) visiting the Eye and ENT hospital of Fudan University from June 2018 to April 2021 were included. Bilateral differential keratometry, elevation, and pachymetry topographies were composed based on raw topographic data obtained by a Scheimpflug imaging anterior segment analyzer. Key bilateral differential characteristic parameters were calculated. SPSS 20 (SPSS Inc., IBM) was used for statistical analyses and the receiver operating characteristic (ROC) curves were used to determine the diagnostic efficacies.Results: Mann-Whitney tests detected that the front keratometry, front elevation, corneal pachymetry, and back elevation maximal, mean, and standard deviation values within a 1.5-mm radius of the bilateral differential topography were all significantly higher in the KC group than in the control group (all p-values <0.001). The front keratometry mean (ΔFKmean) and standard deviation (ΔFKsd) and the front elevation standard deviation (ΔFEsd) and maximal (ΔFEmax) values within a 1.5-mm radius of the bilateral differential topography yielded the four highest accuracies (area under the ROC curve = 0.985, 0.985, 0.984, and 0.983, respectively) for discriminating KC cases (including FFK cases) from normal cases. Cut-off values of 0.75 diopters (D) for the ΔFKmean, 0.67 D for the ΔFKsd, 2.9 μm for the ΔFEsd, and 14.6 μm for the ΔFEmax had the highest sensitivities (95.7, 95.0, 96.9, and 95.0%, respectively) and specificities (96.0, 97.7, 94.8, and 95.4%, respectively).Conclusion: Bilateral differential topographic parameters may be efficient for the early detection of keratoconus and corneal ectasia secondary to corneal refractive surgery. This bilateral differential topographic algorithm may complement conventional diagnostic models by improving the sensitivity and specificity of screening for early keratoconus and ectasia before corneal refractive surgeries.

scholarly journals Correlation between Central Corneal Thickness and Degree of Myopia among Malaysian Patients Undergoing Laser Keratorefractive Surgery

2020 ◽  
pp. 52-58
Author(s):  
Sagili Chandrasekhara Reddy ◽  
Mohd Mansor Shariff ◽  
Aina Malindri Dasrilsyah
Keyword(s):  
Optical Coherence Tomography ◽  
Refractive Surgery ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Military Hospital ◽  
Moderate Degree ◽  
Optical Coherence ◽  
Corneal Refractive Surgery ◽  
The Mean

Purpose: To determine the central corneal thickness in myopic adult patients scheduled for laser corneal refractive surgery and to explore its correlation with degree of refractive error. Materials and Methods: The case records of 130 myopic patients who underwent laser corneal refractive surgery in a military hospital over a period of two years were reviewed to determine the central corneal thickness. All patients had 6/6 vision with best correction, and did not have any other anterior segment or fundus diseases in both eyes. The central corneal thickness was measured with Visante Carl Zeiss anterior segment optical coherence tomography instrument.                                                                                                                        Results: Out of 130 patients, males were more (73, 56.2%); mean age of patients was 33.8 years (range 18-60 years) and majority were Malays (110, 84.6%).  The spherical power of myopia ranged from – 0.5 to – 10.00 D, and the cylindrical power ranged from – 0.25 to – 3.25 D. The mean central corneal thickness of both eyes was 528.2 µm (range 331- 615 µm); in the mild degree of myopia (- 0.50 to - 2.00 D) 527.9 µm, moderate degree (- 2.25 to -5.00 D) 529.4 µm, and high degree (-5.25 to -11.00 D) 523.9 µm. Conclusion: The anterior segment optical coherence tomography provides noncontact, rapid, pachymetry mapping of the corneal thickness. In Malaysian patients, the mean central corneal thickness of both eyes in myopia was 528.1 µm (range 331- 615 µm). There was no correlation between the mean central corneal thickness and degree of myopia, different genders, age groups, ethnic groups and two eyes.

scholarly journals Anterior Segment Eye Assessment of Refractive Surgery Candidates in the Southeast of Iran

2016 ◽  
Vol 8 (12) ◽  
pp. 133 ◽  
Author(s):  
Neda Nakhjavanpour ◽  
Abolfazl Payandeh ◽  
Majid Rajabi ◽  
Vahid Shoja
Keyword(s):  
Anterior Chamber ◽  
Refractive Surgery ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Weather Conditions ◽  
Capital City ◽  
Linear Regression Models ◽  
Corneal Refractive Surgery

<p>Anterior segment eye parameters are essential factors in diagnosis, screening and management of abnormal ocular conditions. Based on the previous studies, they might differ from one race or population to another. Sistan-and-Baluchestan province, the southeast of Iran, has special weather conditions and race, plus lack of research on these diagnostic factors. Hence, the objective of the present study was to assess anterior segment parameters using pentacam in this area. 800 eyes of subjects which had been referred to the Al-Zahra eye hospital of Zahedan, the capital city of the province, for corneal refractive surgery from October 2014 to March 2015 participated in this research. 95% confidence limits for mean of central corneal thickness, anterior chamber depth and volume were (536.02, 541.20), (3.13, 3.18) and (187.63, 192.58) respectively. Multiple linear regression models showed a lower mean central corneal thickness, and maximum/minimum of keratometry, for males than females, adjusting for age and spherical equivalent. Inversely, anterior chamber depth, and volume were more in males. In order to diagnosis and treating ocular diseases which have effect on retinal thickness, precisely specification of predictive factors is highly needed.</p>

scholarly journals Assessment of Corneal Epithelial Thickness in Chronic Contact Lens Users Using Anterior Segment Optical Coherence Tomography

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
A A M E A Rezk ◽  
A Assaf ◽  
M Gamil ◽  
T Badran
Keyword(s):  
Contact Lens ◽  
Corneal Epithelium ◽  
Refractive Surgery ◽  
Anterior Segment ◽  
Control Group ◽  
Soft Contact ◽  
Corneal Epithelial ◽  
Epithelial Thickness ◽  
Soft Contact Lens ◽  
Corneal Epithelial Thickness

Abstract Introduction The corneal epithelium is stratified epithelium that is continuously renewed and provides the frontline of defence against invading ocular pathogens and a smooth refractive surface essential for vision. In the absence of a contact lens, pre-existing ocular trauma or disease, the epithelium maintains an inaccessible defence against attacks from pathogenic microorganisms, affording a high level of resistance against microbial invasion. Aim The aim of this study is to determine the effect of chronic use of contact lens on corneal epithelium thickness using anterior segment optical coherence topography as a non- invasive diagnostic accurate measure. Patients and Methods 30 eyes of control subjects who don’t wear contact lens along their life aged between 15-45 years ,where compared with similar age group of 30 eyes of chronic contact lens users; who wear contact lens every day not less than 8 hours per day for along time interval between 6 months up to 5 years. Results The average corneal epithelial thickness in the central, paracentral and midperipheral zones was 47.767 ± 5.550 µm, 46.267 ± 5.644 µm, 44.300 ± 4.858 µm, respectively, in chronic soft contact lens users; and 49.800 ± 3.316 µm, 49.200 ± 3.367 µm, 45.733 ± 2.333 µm ,in control group who had never worn contact lens. There were insignificant thinning of corneal epithelium of soft contact group compared to control group regarding the average corneal epithelial thickness in those 3 zones. In all the 8 sectors of corneal epithelium of paracentral zone and midperipheral zones there is insignificant thinning between the two groups except for the inferior temporal sector in the paracentral zone and mid peripheral zone, which shows significant thinning in soft contact lens group compared to control group. The corneal epithelial thickness in the inferior temporal sector of paracentral and mid peripheral zones was 46.333 ± 5.677 µm, 44.933 ± 4.813 µm, respectively, in chronic soft contact lens users compared to 48.767 ± 3.266 µm, 46.900 ± 2.510 µm in control group (p = 0.046, p = 0.052, respectively). Conclusion AS-OCT helps us to evaluate the corneal epithelium of contact lens users, which could be very useful in corneal refractive surgeries in patients depending on contact lens in their lives as a comfortable refractive aid, It is necessary to do AS-OCT hand on hand with pentacam in patients underwhelming refractive surgery to give a proper assessment to their corneal epithelium before determining which type of refractive surgery suits them.

scholarly journals Current and new indications for corneal cross-linking in the therapy of corneal diseases

2021 ◽  
Vol 8 (3) ◽  
pp. 186-193
Author(s):  
Katarzyna Przewłócka ◽  
Piotr Kanclerz
Keyword(s):  
Visual Acuity ◽  
Invasive Surgery ◽  
Refractive Surgery ◽  
Cross Linking ◽  
Bullous Keratopathy ◽  
Common Indication ◽  
Corneal Ectasia ◽  
Corneal Refractive Surgery ◽  
Collagen Cross Linking ◽  
Corneal Collagen

Corneal collagen cross-linking, a technique used in ophthalmology, involves the creation of new bonds between collagen fibers, thus leading to stabilization and corneal stiffening. The most common indication for corneal collagen cross-linking procedures is to prevent the progression of corneal ectasia,\ i.e., keratoconus, pellucid marginal degeneration, and ectasia after corneal refractive surgery. Clinical data also indicate that it is effective in the treatment of bacterial corneal infections and bullous keratopathy. Corneal collagen cross-linking was shown to inhibit the progression of corneal ectasia, and the treatment commonly leads to the improvement in visual acuity, decreases the maximum keratometry values, and improves the corneal topography image. In addition, it is possible to avoid or postpone the need for more complex and invasive surgery.

scholarly journals Do We Have a Place for Non-Steroidal Anti-Inflammatory Drugs in Corneal Refractive Surgery?

2021 ◽  
Vol 18 (3) ◽  
pp. 539-545
Author(s):  
N. V. Maychuk ◽  
I. A. Mushkova ◽  
M. R. Obraztsova
Keyword(s):  
Postoperative Period ◽  
Analgesic Effect ◽  
Refractive Surgery ◽  
State Institution ◽  
Early Postoperative Period ◽  
Main Group ◽  
Federal State ◽  
Control Group ◽  
Wide Range ◽  
Corneal Refractive Surgery

Relevance. Corneal refractive surgery is a modern, dynamically developing segment of ophthalmology that provides highly predictable, safe and stable refractive results in patients with a wide range of ametropias. Corneal refractive surgery, usually is chosen by patients who lead an active lifestyle and need rapid medical and social rehabilitation, people with high requirements for the quality of life and showing increased expectations for the result of correction. Perhaps this is due to the fact that, according to a survey at the exit of the Department of refractive laser Surgery of the S.N. Fyodorov Eye Microsurgery Federal State Institution of the Russian Ministry of Health, Moscow, conducted after consulting a surgeon with a description of the course of the operation and the postoperative course, about 1 % of patients refuse surgery, fearing painful sensations in the postoperative period, and 23.4 % of the expected postoperative discomfort causes strong concerns.Purpose. To study the clinical efficacy and safety of Broxinac (0.09 % bromfenac solution) in the early postoperative period of corneal refractive surgery.Materials and methods. The study included 168 patients (168 eyes) with moderate and high myopia after PRK (24 eyes), FemtoLASIK (78 eyes) and ReLEx SMILE (66 eyes), divided into equal subgroups: in the main group, Broxinac was instilled once 30 minutes after the operation, and in the control group — placebo. In the PRK subgroup of the main group, daily instillations of Broxinac were continued until complete reepithelization. The severity of the indicators “eye pain”, “photophobia”, “lacrimation”, “foreign body sensation” was evaluated on a five-point scale, the state of the corneal epithelium when stained with fluorescein, and overall satisfaction with the operation.Results and discussion. It is established that the analgesic effect occurred on average after 4.4 ± 0.6 minutes. Broxinac had a rapid, pronounced analgesic effect in patients in the early postoperative period after keratorefractive surgery, without slowing of corneal reepithelization, and can be recommended for use in clinical practice for analgesia and relief of aseptic inflammatory reaction in the early postoperative period after FemtoLASIK and PRK. The ReLEx SMILE does not require pain relief.Conclusion. Analgesia of the early postoperative period increases patient satisfaction with the result of the operation, popularizes it and helps to attract patients who previously refused surgical correction of ametropia due to fear of painful sensations.

scholarly journals Study on the corneal higher-order aberrations and correlation in patients with different degrees of myopia suitable for wavefront-guided FS-LASIK

2019 ◽  
Author(s):  
Cheng-Zhe Wu ◽  
Xun Cui ◽  
Zheng-Ri Li ◽  
Hong Cui ◽  
Hua Jin ◽  
...  
Keyword(s):  
Refractive Surgery ◽  
Spherical Aberration ◽  
Anterior Segment ◽  
Higher Order ◽  
Spherical Equivalent ◽  
Higher Order Aberrations ◽  
Wavefront Aberrations ◽  
The Third ◽  
Corneal Refractive Surgery ◽  
Analysis System

Abstract Background: To investigate the characteristics and distribution of anterior and posterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 14-46 years old) who underwent corneal refractive surgery were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -1.50 to -12.00 D. The corneal anterior and posterior aberrations (higher-order aberration, HOA; spherical aberration, SA; Coma; Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the ocular and corneal wave surface aberrations at a 6.0-mm pupil showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma ratio: coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/ total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19±0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P=0.013). The spherical equivalent was positively correlated with the corneal coma of the preoperative anterior corneal surfaces (R=-0.241, P=0.009), and the Q value was positively correlated with the total higher-order aberrations (R=0.326, P<0.001). Conclusions: Individual wavefront aberrations on the anterior and posterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

scholarly journals Diagnostic imaging versus surgical procedure: intra- and postoperative OCT evaluation of sutureless scleral-fixated intraocular lens implantation and possible related complications

2021 ◽  
Author(s):  
Raffaele Nuzzi ◽  
Alessandro Rossi
Keyword(s):  
Intraocular Lens ◽  
Refractive Surgery ◽  
Anterior Segment ◽  
Iol Implantation ◽  
Anterior Segment Oct ◽  
Preoperative Stage ◽  
Lens Implantation ◽  
Corneal Refractive Surgery ◽  
Capsular Bag ◽  
Scleral Fixated Intraocular Lens

AbstractBecause the popularity of corneal refractive surgery has been increasing throughout the last 25 years, many authors have thought to apply optical coherence tomography (OCT) to the anterior segment (AS-OCT); by revising the instrumentation needed and slightly improve the technique, it has become an element of vital importance in order to ensure a complete and exhaustive pre- and postsurgical evaluation. Many applications of OCT have been recently developed—mostly in cataract surgery due to the increasing numbers—such as chamber biometry, which is used in a preoperative stage to determine the details of IOL implantation, and lens evaluation. The aim of this review is to assess the applications of anterior segment OCT in dislocated IOL and/or capsular bag exchange surgery with scleral sutureless fixated intraocular lens and monitoring of possible postoperative complications.

scholarly journals The role of epithelial thickness mapping in corneal refractive surgery

2021 ◽  
Vol 8 (3) ◽  
pp. 196-201
Author(s):  
Aleksandra Wlaź ◽  
Barbara Czarnota-Nowakowska ◽  
Joanna Wierzbowska
Keyword(s):  
Refractive Surgery ◽  
New Technologies ◽  
Anterior Segment ◽  
Efficacy And Safety ◽  
Significant Progress ◽  
Corneal Epithelial ◽  
Epithelial Thickness ◽  
Corneal Refractive Surgery ◽  
Anterior Segment Imaging

Refractive surgery has stimulated significant progress in anterior segment imaging. Knowledge of epithelial thickness profile considerably increases the efficacy and safety of refractive procedures. This review aims to present new technologies evaluating corneal epithelial thickness and the most important clinical applications in the field of corneal refractive surgery.

scholarly journals Red blood cell distribution width-standard deviation but not red blood cell distribution width-coefficient of variation as a potential index for the diagnosis of iron-deficiency anemia in mid-pregnancy women

2021 ◽  
Vol 16 (1) ◽  
pp. 1213-1218
Author(s):  
Yang Kai ◽  
Pan Ying ◽  
Yan Bo ◽  
Yu Furong ◽  
Chen Jin ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Blood Cell ◽  
Red Blood Cell ◽  
Roc Curves ◽  
Deficiency Anemia ◽  
Control Group ◽  
Cell Distribution ◽  
Distribution Width ◽  
Width Coefficient ◽  
Red Blood Cell Distribution

Abstract The aim of this study was to compare the diagnostic values of red blood cell distribution width-coefficient of variation (RDW-CV) and red blood cell distribution width-standard deviation (RDW-SD) in mid-pregnancy women with iron deficiency anemia (IDA). To obtain the results, 115 mid-pregnancy women with IDA, defined as the IDA group, and 142 healthy mid-pregnancy women, selected as the control group, were enrolled in this study. Hematological parameters and ferritin concentrations in the serum were analyzed. The efficiency of RDW-CV and RDW-SD to distinguish IDA from mid-pregnancy women was evaluated using receiver operating characteristic (ROC) curves. The RDW-SD value in the IDA group was significantly higher than that in the control group (p < 0.05), while the RDW-CV value did not differ between them (p = 0.84). Significantly negative correlations were found between RDW-CV (r = −0.297, p = 0.001), RDW-SD (r = −0.404, p = 0.000), and serum ferritin in the IDA group but not in the control group. For the diagnosis of IDA, RDW-CV and RDW-SD produced areas under the ROC curves of 0.58 and 0.84. To conclude, our results suggest that RDW-SD, but not RDW-CV, can be used as a diagnostic index of IDA for mid-pregnancy women.

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