scholarly journals Corneal biomechanical metrics in thin cornea of normal, keratoconus suspect and keratoconus in Egyptian population

2019 ◽  
Author(s):  
Adel Galal Zaky ◽  
Mohamed Samy Abd Elaziz ◽  
Hatem Mohamed Marey ◽  
Moatz Faiz Elsawy ◽  
Nermeen Mahmoud Badawi ◽  
...  
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Study Groups ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Main Concern ◽  
Test Results ◽  
Corneal Resistance Factor ◽  
Significant Difference ◽  
The Mean

Abstract Background To assess and compare corneal hysteresis (CH) and corneal resistance factor (CRF) in normal thin (NT) healthy corneas with central corneal thickness (CCT) 470-500 µm with matched thickness in keratoconus (KC) and keratoconus suspect (KCS) eyes. Methods A total of 66 eyes in three groups were included prospectively: NT, KCS and KC groups based on clinical examination and topography. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the ocular response analyzer. CH and CRF were compared between the three groups and statistically analyzed by variances test. Results The three groups consisted of 32 NT, 19 KCS, and 15 KC. The mean CH measured was 8.55± 1.77, 9.03± 1.119 and 8.06 ± 0.85 mm Hg in NT, KCS and KC eyes, respectively. The mean CRF was 8.39 ± 1.47, 8.27 ± 1.09 and 7.24 ± 1.27 mm Hg in NT, KCS and KC eyes, respectively. Within range of central corneal thickness (470 – 500 µm), only mean CRF was statistically significantly different between the NT and KC (P < 0.05); there was no statistically significant difference between NT and KCS, nor the mean CH between each groups (P > 0.05). Conclusions CRF only can be helpful in differentiating KC from NT eyes; however, it’s not valuable for detecting KCS which is the main concern for refractive surgery. No benefit from CH in differentiating between the study groups. Further investigations & work focusing on more accurate tests for identifying KCS are still needed.

scholarly journals Biomechanical Properties in Different Types of Thin Corneas in Menoufia Population

2020 ◽  
Author(s):  
Adel Galal Zaky ◽  
Amin Faisal Ellakwa ◽  
Ahmed Ibrahim Basiony
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Study Groups ◽  
Biomechanical Properties ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Corneal Resistance Factor ◽  
Significant Difference ◽  
Different Types ◽  
The Mean

Abstract Background:To evaluate and compare corneal hysteresis (CH) and corneal resistance factor (CRF) in normal thin (NT) healthy corneas with central corneal thickness (CCT) 470-500 µm with matched thickness in keratoconus suspect (KCS) and keratoconus (KC) and eyes.Methods: A total of 103 eyes in three groups were included prospectively: NT, KCS and KC groups based on clinical examination and pentacam findings. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured by the ocular response analyzer (ORA). CCT ,CH and CRF were compared between the three groups and statistically analyzed by variance tests.Results:The three groups consisted of 44 NT, 26 KCS, and 33 KC. The mean CH measured was 8.689 ± 1.775, 9.051 ± 1.1190 and 8.129 ± 0.8539 mmHg in NT, KCS and KC eyes, respectively. The mean CRF was 8.441 ± 1.663, 8.337 ± 1.114 and 7.2422 ± 1.3110 mmHg in NT, KCS and KC eyes, respectively. Within range of central corneal thickness (470 – 500 µm), only mean CRF was statistically significantly different between the NT and KC (P < 0.05); there was no statistically significant difference between NT and KCS, nor the mean CH between each group (P > 0.05).Conclusions: CRF only can be helpful in differentiating KC from NT eyes; KCS could not be predicted with either corneal biomechanical metrics. No benefit from CH in differentiating between the three study groups.

scholarly journals Biomechanical Properties in Different Types of Thin Corneas in Menoufia Population

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Adel Galal Zaky ◽  
Amin Faisal Ellakwa ◽  
Ahmed Ibrahim Basiony
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Study Groups ◽  
Biomechanical Properties ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Corneal Resistance Factor ◽  
Significant Difference ◽  
Different Types ◽  
The Mean

Background. To evaluate and compare corneal hysteresis (CH) and corneal resistance factor (CRF) in normal thin (NT) healthy corneas with central corneal thickness (CCT) of 470–500 μm with matched thickness in keratoconus suspect (KCS) and keratoconus (KC) eyes. Methods. A total of 103 eyes in three groups were included prospectively: NT, KCS, and KC groups based on clinical examination and Pentacam findings. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the ocular response analyzer (ORA). CCT, CH, and CRF were compared between the three groups and statistically analyzed by variance tests. Results. The three groups consisted of 44 NT, 26 KCS, and 33 KC. The mean CH measured was 8.689 ± 1.775, 9.051 ± 1.1190, and 8.129 ± 0.8539 mmHg in NT, KCS, and KC eyes, respectively. The mean CRF was 8.441 ± 1.663, 8.337 ± 1.114, and 7.2422 ± 1.3110 mmHg in NT, KCS, and KC eyes, respectively. Within the range of central corneal thickness (470–500 μm), only mean CRF was statistically significantly different between the NT and KC ( P < 0.05 ); there was no statistically significant difference between NT and KCS, nor was the mean CH between each group ( P > 0.05 ). Conclusions. CRF only can be helpful in differentiating KC from NT eyes; KCS could not be predicted with either corneal biomechanical metrics. There was no benefit from CH in differentiating between the three study groups.

Changes in corneal biomechanics during pregnancy in Chinese healthy female

2020 ◽  
pp. 112067212090203
Author(s):  
Yaping Yang ◽  
Jun Ye ◽  
Tsz Kin Ng ◽  
Na Wu ◽  
Xinghuai Sun ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Pregnant Women ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Corneal Resistance Factor ◽  
Third Trimester ◽  
The Third ◽  
Healthy Female

Purpose: To evaluate the changes of corneal biomechanics and the intraocular pressure during pregnancy in a Chinese healthy female population. Methods: A total of 222 unrelated Chinese females were recruited: 52 non-pregnant, 15 pregnant in the first trimester, 68 pregnant in the second trimester, and 87 pregnant in the third trimester. The intraocular pressure and corneal biomechanical parameters, including corneal-compensated intraocular pressure, Goldmann-correlated intraocular pressure, corneal hysteresis, and corneal resistance factor, were measured by an Ocular Response Analyzer G3. Central corneal thickness was measured by Lenstar (LS900). Results: Corneal hysteresis and corneal resistance factor were significantly higher in pregnant women at the second and third trimesters. Corneal-compensated intraocular pressure was lower in women at the third trimester of pregnancy ( p = 0.023), but the difference became insignificant after adjustment for corneal hysteresis. Central corneal thickness was marginally higher in pregnant women than non-pregnant women ( p = 0.032). There was a negative correlation between corneal-compensated intraocular pressure and corneal hysteresis ( r = −0.337, p < 0.001) and a positive correlation between central corneal thickness and corneal hysteresis ( r = 0.711, p < 0.0001). After adjustment for corneal-compensated intraocular pressure, corneal hysteresis remained significantly higher in the second and third trimesters of pregnant women than non-pregnant women ( p = 0.031, p = 0.005). Conclusion: This study revealed a significant increase in corneal hysteresis and corneal resistance factor in the second and third trimesters. The increase of corneal hysteresis was independent of corneal-compensated intraocular pressure, indicating pregnant females have unique characteristics in corneal-compensated intraocular pressure and corneal biomechanical properties that may be related to glaucoma and corneal ectatic diseases in pregnancy.

scholarly journals Corneal Biomechanical Parameters and Central Corneal Thickness in Glaucoma Patients, Glaucoma Suspects, and a Healthy Population

2021 ◽  
Vol 10 (12) ◽  
pp. 2637
Author(s):  
Mª. Ángeles del Buey-Sayas ◽  
Elena Lanchares-Sancho ◽  
Pilar Campins-Falcó ◽  
María Dolores Pinazo-Durán ◽  
Cristina Peris-Martínez
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Mean Difference ◽  
The Other ◽  
Control Group ◽  
Healthy Population ◽  
Diagnostic Categories ◽  
Significant Difference ◽  
Biomechanical Parameters ◽  
The Mean

Purpose: To evaluate and compare corneal hysteresis (CH), corneal resistance factor (CRF), and central corneal thickness (CCT), measurements were taken between a healthy population (controls), patients diagnosed with glaucoma (DG), and glaucoma suspect patients due to ocular hypertension (OHT), family history of glaucoma (FHG), or glaucoma-like optic discs (GLD). Additionally, Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated IOP (IOPcc) were compared between the different groups of patients. Methods: In this prospective analytical-observational study, a total of 1065 patients (one eye of each) were recruited to undergo Ocular Response Analyzer (ORA) testing, ultrasound pachymetry, and clinical examination. Corneal biomechanical parameters (CH, CRF), CCT, IOPg, and IOPcc were measured in the control group (n = 574) and the other groups: DG (n = 147), FHG (n = 78), GLD (n = 90), and OHT (n = 176). We performed a variance analysis (ANOVA) for all the dependent variables according to the different diagnostic categories with multiple comparisons to identify the differences between the diagnostic categories, deeming p < 0.05 as statistically significant. Results: The mean CH in the DG group (9.69 mmHg) was significantly lower compared to controls (10.75 mmHg; mean difference 1.05, p < 0.001), FHG (10.70 mmHg; mean difference 1.00, p < 0.05), GLD (10.63 mmHg; mean difference 0.93, p < 0.05) and OHT (10.54 mmHg; mean difference 0.84, p < 0.05). No glaucoma suspects (FHG, GLD, OHT groups) presented significant differences between themselves and the control group (p = 1.00). No statistically significant differences were found in the mean CRF between DG (11.18 mmHg) and the control group (10.75 mmHg; mean difference 0.42, p = 0.40). The FHG and OHT groups showed significantly higher mean CRF values (12.32 and 12.41 mmHg, respectively) than the DG group (11.18 mmHg), with mean differences of 1.13 (p < 0.05) and 1.22 (p < 0.001), respectively. No statistically significant differences were found in CCT in the analysis between DG (562 μ) and the other groups (control = 556 μ, FHG = 576 μ, GLD = 569 μ, OHT = 570 μ). The means of IOPg and IOPcc values were higher in the DG patient and suspect groups than in the control group, with statistically significant differences in all groups (p < 0.001). Conclusion: This study presents corneal biomechanical values (CH, CRF), CCT, IOPg, and IOPcc for diagnosed glaucoma patients, three suspected glaucoma groups, and a healthy population, using the ORA. Mean CH values were markedly lower in the DG group (diagnosed with glaucoma damage) compared to the other groups. No significant difference was found in CCT between the DG and control groups. Unexpectedly, CRF showed higher values in all groups than in the control group, but the difference was only statistically significant in the suspect groups (FHG, GLD, and OHT), not in the DG group.

scholarly journals Usefulness of the Non-Contact Tonometry in Out-Patient Screening

2016 ◽  
Vol 15 (2) ◽  
Author(s):  
Satheesh Solomon T Selvin ◽  
Chris Elsa Samson Jacob ◽  
Thomas Kuriakose
Keyword(s):  
Central Corneal Thickness ◽  
Care Center ◽  
Corneal Thickness ◽  
Tertiary Care ◽  
Cross Sectional Study ◽  
Applanation Tonometry ◽  
Cross Sectional ◽  
Significant Difference ◽  
Iop Measurement ◽  
The Mean

Purpose: Goldmann applanation tonometry (GAT) is considered the gold standard for Intraocular Pressure (IOP) measurement. It has the disadvantages of being a contact device, need for a slit-lamp, non-portability and need of a skilled examiner. Many hospitals are using a Non Contact Tonometry (NCT) as a screening device to save clinician time, however the usefulness is not proved in terms of reliability. This study was aimed to determine the usefulness of the Air-puff tonometer (TONOREF NIDEK II, NIDEK CO., LTD., JAPAN) over a GAT in a tertiary care center. Design: Cross-sectional Study Methods: This was a cross-sectional, non interventional observational study conducted on 224 eyes (right eye) from 224 patients. All patients underwent the IOP measurement with both methods and a central corneal thickness (CCT) measured. The data was analyzed using SPSS 20.0 software. Results: The mean age of the patients was 40.3±11.29 years. There was a statistically significant difference (p<0.001) between the mean NCT and GAT readings which persisted even after correction for central corneal thickness. The correlation between NCT and GAT using Pearson’s correlation coefficient was strong irrespective of the corrections for their corneal thickness (r = 0.751 and 0.718 for uncorrected and corrected values respectively). The correlation of the individual clinicians for the readings varied from moderate to strong. The ROC curve showed the best sensitivity and specificity to occur at around 13 to 14 mmHg. Conclusion: NCT seems to overestimate the IOP at low ranges as compared to the GAT and underestimate at higher ranges. The crossover of the values is seen between 12 to 13 mmHg.  The clinician should do an individualized analysis of his/her GAT measurements to the readings of the NCT machine at the clinic to obtain clinician specific nomogram. 

scholarly journals The pattern of central corneal thickness in patients attending a Tertiary Hospital in Dar-Es-Salaam

2021 ◽  
Vol 9 (2) ◽  
pp. 127-133
Author(s):  
Annamary Stanislaus ◽  
Ntsilane Susan Mosenene ◽  
Celina Mhina ◽  
John Stanslaus Kisimbi ◽  
Frederick Robert Burgess ◽  
...  
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Dar Es Salaam ◽  
Applanation Tonometry ◽  
P Value ◽  
Muhimbili National Hospital ◽  
National Hospital ◽  
Cross Sectional ◽  
Significant Difference ◽  
The Mean

Background: Central Corneal Thickness (CCT) is an indicator of corneal health status as well as being an essential tool in assessment and management of corneal diseases. It is an important factor in the diagnosis and management of glaucoma as it affects the measurement of intraocular pressure. However, the pattern of central corneal thickness in our population is not known. Our study aimed to describe the CCT measurements and their variation with age and sex among patients attending the eye clinic at Muhimbili National Hospital (MNH), in Dar es Salaam, Tanzania. Methodology: A hospital-based descriptive, cross-sectional study used convenient sampling to recruit adult patients aged 18 years and above, presenting to the MNH between August 2016 and January 2017.Visual acuity assessment, Goldman applanation tonometry and CCT assessment using an ultrasound pachymeter were performed. Patients with previous intraocular surgery were excluded. Results: A total of 398 patients (208 males and 190 females) were recruited. The mean CCT was 526.64±38.30 µm; being 523.99±38.20 µm for males and 529.7±38.3 µm for females. 226 (56.85%) had CCT of less than 520 µm.There was no statistically significant difference in CCT between gender. The proportion of patients with thinner CCT increased with increasing age from 25.8% in those < 30 years to 75% in those aged 71years and above. The mean CCT decreased with increasing age with P-value<0.001. Conclusion: The average CCT in patients attending Muhimbili National Hospital is 526.64 µm (SD 38.30) which is generally thin, inversely proportion to age and similar that of other Africans and African-Americans. This finding has implications for the management of glaucoma in this population.

Relationship between novel intraocular pressure measurement from Corvis ST and central corneal thickness and corneal hysteresis

2019 ◽  
Vol 104 (4) ◽  
pp. 563-568 ◽  
Author(s):  
Masato Matsuura ◽  
Hiroshi Murata ◽  
Yuri Fujino ◽  
Mieko Yanagisawa ◽  
Yoshitaka Nakao ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Central Corneal Thickness ◽  
Linear Regression Analysis ◽  
Corneal Thickness ◽  
Biomechanical Properties ◽  
Applanation Tonometry ◽  
Corneal Hysteresis ◽  
Corneal Resistance Factor ◽  
Corvis St ◽  
The Relationship

AimsCorvis ST (CST) yields biomechanical corrected IOP (bIOP) which is purported to be less dependent on biomechanical properties. In our accompanied paper, it was suggested that the repeatability of bIOP is high. The purpose of the current study was to assess the relationship between intraocular pressure (IOP) measured with CST and central corneal thickness (CCT) and corneal hysteresis (CH), in comparison with IOP measured with Goldmann applanation tonometry (GAT) and the ocular response analyzer (ORA).MethodsA total of 141 eyes from 141 subjects (35 healthy eyes and 106 glaucomatous eyes) underwent IOP measurements with GAT, CST and ORA. The relationships between IOP measurements (ORA-IOPg, ORA-IOPcc, CST-bIOP and GAT IOP) and biomechanical properties (CCT, CH and corneal resistance factor (CRF)) were analysed using the linear regression analysis.ResultsIOPg, IOPcc and GAT IOP were significantly associated with CCT (p<0.001), whereas bIOP was not significantly associated with CCT (p=0.19). IOPg, bIOP and GAT IOP were significantly associated with CH (IOPg: p<0.001; bIOP: p<0.001; GAT IOP: p=0.0054), whereas IOPcc was not significantly associated with CH (p=0.18). All of IOP records were associated with CRF (p<0.001).ConclusionThe bIOP measurement from CST is independent from CCT, but dependent on CH and CRF.

Evaluation of biometric parameters in phacomorphic glaucoma and mature cataracts

2020 ◽  
pp. 112067212091453
Author(s):  
Ali Keleş ◽  
Emine Şen ◽  
Ufuk Elgin
Keyword(s):  
Anterior Chamber ◽  
Axial Length ◽  
Odds Ratio ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Chamber Depth ◽  
Mature Cataract ◽  
Biometric Parameters ◽  
Significant Difference ◽  
The Mean

Purpose: The aims of this study were to compare the biometric parameters and axial lengths of eyes with phacomorphic glaucoma and mature cataract and to identify differences that might predispose to development of phacomorphic glaucoma. Methods: Three hundred forty-two patients were enrolled in this retrospective study. The eyes were divided into four groups—Group (G)1: phacomorphic glaucoma ( n = 29), G2: mature cataract ( n = 313), G3: contralateral phacomorphic glaucoma ( n = 29), and G4: contralateral mature cataract ( n = 313). Central corneal thickness and anterior chamber depth were assessed by optical low-coherence reflectometry (Lenstar LS 900®; Haag-Streit AG, Switzerland), while axial length was determined by A-scan ultrasound biometry. Results: The mean central corneal thickness of G1 was significantly higher than in other groups ( p < 0.001) and the mean anterior chamber depth of G1 was the lowest among the groups ( p < 0.001). Also, G2 had lower mean anterior chamber depth than G4 ( p < 0.001) and G3 had lower mean anterior chamber depth than G4 ( p = 0.007). Anterior chamber depth less than 3.27 mm had the higher odds ratio for distinguishing G3 versus G4 (odds ratio = 10.79, p < 0.001). Furthermore, patients aged ⩾68.9 years had the higher odds ratio for distinguishing G1 versus G2 (odds ratio = 2.82, p = 0.019). There was no significant difference in the presence of pseudoexfoliation material between G1 and G2 ( p = 0.057). There were no significant differences in axial length values among the four groups ( p = 0.097). Conclusion: Advanced age and shallow anterior chamber depth were found to be risk factors for developing phacomorphic glaucoma, but the presence of pseudoexfoliation material was not found to play a role as a risk factor in phacomorphic glaucoma development.

scholarly journals A comparative study of central corneal thickness, mean keratometry and astigmatism in persons with and without refractive errors in Taif

2018 ◽  
Vol 5 (2) ◽  
pp. 416
Author(s):  
Afnan H. Alqurashi ◽  
Omayma K. Afifi ◽  
Hatim F. Jabr ◽  
Hanan A. Aljuaid
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Reference Value ◽  
Refractive Errors ◽  
Average Value ◽  
Significant Difference ◽  
Standard Normal ◽  
Km Value ◽  
Group A ◽  
The Mean

Background: Corneal topography is an important parameter in the evaluation of corneal disease, but there is no average value of normal corneal geometry in Saudi individuals is known. So, this study aimed to establish a standard normal value for central corneal thickness (CCT), mean keratometry (km), and astigmatism in Saudi individuals to be used as a reference value, and to compare these results with the same parameters in patients who have refractive errors. Methods: This study was performed from January 2016 to July 2017 at King Faisal Hospital in Taif, KSA, and included a current group of 105 eyes without refractive errors, and 250 eyes with refractor errors. Results: The mean CCT value was 551.681 µm, km value was 43.426 D, and astigmatism was 0.784 D for all eyes with normal visual acuity. However, these values are the statistically significant difference between different ages, but no significant differences according to sex. Regarding the eyes with refractive error, it was found that the mean CCT was 509.66 µm, km was 46.79 D, and for astigmatism was 3.97 D. When the results of two groups were compared, there was a significant difference between them except for km in the group a; (12-20 years). Conclusions: The standard value of central corneal thickness, mean keratometry, and astigmatism in Saudi individuals is differing according to the age but it is the same in both genders. These values are differing statistically in patients with refractor error. 

scholarly journals Presbyopia and its anatomical and physiological variants

1970 ◽  
Vol 3 (2) ◽  
pp. 155-158
Author(s):  
M Gupta ◽  
RR Sukul ◽  
Y Gupta ◽  
M Dey ◽  
A Phougat ◽  
...  
Keyword(s):  
Anterior Chamber ◽  
Axial Length ◽  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Anterior Chamber Depth ◽  
Physiological Parameters ◽  
Corneal Curvature ◽  
Lens Thickness ◽  
Significant Difference ◽  
The Mean

Aim: To study the various ocular anatomical and physiological parameters in presbyopia. Materials and methods: We studied the various ocular anatomical and physiological parameters like corneal curvature (keratometry readings: K1 and K2), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT) and axial length (AL) in 100 presbyopic patients between 35 - 55 years of age. The patients were divided into two age groups: I (35 – 44 years) and II (45-55 yrs). ACD, AL and LT were measured using an Ascan. CCT was measured with ultrasonic pachymetry. Results: The CCT decreased (BE), LT increased and ACD decreased (RE) significantly with increasing age (p < 0.05). There was no significant difference in males and females. Nearly 3/4th of the total increase in lens thickness was responsible for the decrease in the anterior chamber depth and the rest, 1/4th , goes posteriorly. Corneal curvature and AL showed no significant change with age. Conclusions: The mean of CCT decreased significantly with advancing age. As age increased, the mean value of lens thickness increased and anterior chamber depth decreased. Nearly 3/ 4th of total increase in LT was anteriorly, decreasing the ACD. Corneal curvature and AL has no relation with age. Key words: Presbyopia, central corneal thickness, anterior chamber depth, lens thickness, axial length DOI: http://dx.doi.org/10.3126/nepjoph.v3i2.5269 Nepal J Ophthalmol 2011; 3(2): 155-158

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