scholarly journals Corneal Biomechanical Changes in Third Trimester of Pregnancy

Medicina ◽  
2021 ◽  
Vol 57 (6) ◽  
pp. 600
Author(s):  
Inna Adriana Bujor ◽  
Raluca Claudia Iancu ◽  
Sînziana Luminiţa Istrate ◽  
Emil Ungureanu ◽  
George Iancu
Keyword(s):  
Intraocular Pressure ◽  
Sex Hormones ◽  
Statistical Significance ◽  
Retinal Pigment ◽  
Resistance Factor ◽  
Corneal Biomechanics ◽  
Corneal Hysteresis ◽  
Corneal Resistance Factor ◽  
Third Trimester ◽  
The Third

Background and Objectives: There is a clear evidence that pregnancy is associated with high production of sex hormones. During the first, second and third trimester of pregnancy, blood hormones levels increase gradually. Cells with affinity for sex hormones have been identified in different ocular tissues, such as: lid, lacrimal gland, meibomian gland, bulbar and palpebral conjunctivae, cornea, iris, ciliary body, lens, retina (retinal pigment epithelium) and choroid. This is why pregnancy is associated with changes at ocular level, involving anterior and posterior segments. Several clinical trials have been made trying to highlight changes in corneal biomechanics during pregnancy. By conducting this review, we want to evaluate both the changes in parameters that define corneal biomechanics and intraocular pressure values in pregnant. Materials and Methods: Following a systematic search in the literature related mainly to changes in corneal biomechanics during pregnancy, focusing on the paper published in the last decade, we included in a meta-analysis the cumulative results of three prospective comparative studies. Results: Important changes in corneal biomechanics (corneal hysteresis and corneal resistance factor) parameters were observed in women in the third trimester of pregnancy, but these variations were not statistically significant. Also, a decrease in intraocular pressure was mentioned in these women, but only the corneal compensation intraocular pressure showed a decrease with statistical significance. Conclusions: A decrease in corneal compensatory intraocular pressure was observed in pregnant women in the third trimester of pregnancy, but without other statistically significant changes resulting from the analysis of the other three parameters (corneal hysteresis, corneal resistance factor and Goldmann-correlated intraocular pressure).

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.

Corneal Hysteresis, Corneal Resistance Factor, and Intraocular Pressure Measurements in Eyes Implanted With a Small Aperture Corneal Inlay

2014 ◽  
Vol 30 (12) ◽  
pp. 831-836 ◽  
Author(s):  
Alper Agca ◽  
Ahmet Demirok ◽  
Haci Ugur Çelik ◽  
Corina van de Pol ◽  
Kadir Ilker Çankaya ◽  
...  
Keyword(s):  
Intraocular Pressure ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Pressure Measurements ◽  
Corneal Resistance Factor ◽  
Small Aperture ◽  
Corneal Inlay

scholarly journals Collagen Cross-Linking and Keratoconus in Pediatric Patients

2012 ◽  
Vol 1 (1) ◽  
pp. 57-60 ◽  
Author(s):  
Joseph Pikkel ◽  
Hanna Garzozi
Keyword(s):  
Visual Acuity ◽  
Intraocular Pressure ◽  
Pediatric Patients ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Cross Linking ◽  
Corneal Resistance Factor ◽  
Corrected Visual Acuity ◽  
Uncorrected Visual Acuity ◽  
Collagen Cross Linking

ABSTRACT Purpose To evaluate the efficacy of corneal cross-linking on keratoconic eyes in the pediatric age group. Setting Private laser center, Haifa, Israel, affiliated to Hadassah Hospital, Jerusalem. Methods This is a retrospective study of 29 eyes of 20 children treated with corneal cross-linking with aim to arrest the progression of keratoconus. We preformed collagen corneal cross-linking using riboflavin 0.1% and UVA irradiation. Follow- up ranged between 6 and 46 months (mean 25.5 months). Evaluation included uncorrected visual acuity, best spectacle corrected visual acuity, manifest refraction, slit lamp examination and corneal topography. Ocular response analyzer was used to assess the corneal resistance factor, corneal hysteresis and cornea compensated intraocular pressure. Results The results show improvement in uncorrected visual acuity and best spectacle-corrected visual acuity and reduction in astigmatism. There was no statistically significant change in sphere, keratometry, corneal resistance factor, corneal hysteresis or cornea compensated intraocular pressure. Conclusion Corneal cross-linking demonstrates efficacy in arresting the progression of keratoconus as well as improving uncorrected and best corrected visual acuity and reducing astigmatism. How to cite this article Barbara R, Pikkel J, Garzozi H, Barbara A. Collagen Cross-Linking and Keratoconus in Pediatric Patients. Int J Keratoco Ectatic Corneal Dis 2012;1(1):57-60.

scholarly journals Use of Corneal hysteresis and Corneal Resistance Factor in Target Intraocular Pressure Estimation in Patients with Early Primary Open Angle Glaucoma

2021 ◽  
Author(s):  
Moataz Sallam ◽  
Mervat E. Elghareib
Keyword(s):  
Intraocular Pressure ◽  
Negative Correlation ◽  
Primary Open Angle Glaucoma ◽  
Open Angle Glaucoma ◽  
Significant Negative Correlation ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Open Angle ◽  
Corneal Resistance Factor ◽  
Early Primary

Abstract Purpose: To introduce a new method for estimation of the target intraocular pressure (TIOP) in naïve eyes with early primary open angle glaucoma (POAG) using Corneal hysteresis (CH) and corneal resistance factor (CRF).Methods: A prospective quasi-experimental study was conducted on naïve 90 eyes of 45 patients who were newly diagnosed with early primary open angle glaucoma (POAG). They were compared to 72 eyes of 36 normal subjects. The TIOP was determined for each eye. The IOP Goldmann (IOPg), IOP corneal-compensated (IOPcc), CH and CRF were estimated by Ocular Response Analyzer (ORA, Reichert) device. Measurements were taken for each patient prior to treatment and after 1, 3, 6, 9 and 12 months of receiving medications; either monotherapy or combination therapy.Results: For all patients, there was a significant negative correlation (p < 0.05) between IOP, either IOPg or IOPcc, and CH while a significant positive relationship (p < 0.05) existed between IOP and CRF. For patients with early POAG, The CH was significantly increased (p ≤ 0.001) while CRF was significantly decreased (p ≤ 0.001) when TIOP was achieved. At IOP levels higher than TIOP, CH value was lower than CRF with a significant negative correlation between them in contrast to controls. This correlation was reversed on reaching TIOP and CH values became higher than CRF similar to controls.Conclusion: CH, CRF and IOP measured by ORA can be used for TIOP estimation. This provides us with a guide for assessing the effectiveness of medications introduced to patients with POAG.

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.

scholarly journals Conventional Versus Accelerated Collagen Cross-Linking for Keratoconus: A Comparison of Visual, Refractive, Topographic and Biomechanical Outcomes

2017 ◽  
Vol 11 (1) ◽  
pp. 262-272 ◽  
Author(s):  
Jyh Haur Woo ◽  
Jayant Venkatramani Iyer ◽  
Li Lim ◽  
M Htoon Hla ◽  
Jodhbir S Mehta ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Endothelial Cell ◽  
Cell Loss ◽  
Corneal Topography ◽  
Resistance Factor ◽  
Corneal Hysteresis ◽  
Cross Linking ◽  
Corneal Resistance Factor ◽  
Accelerated Crosslinking

Objective: The aim was to compare the visual, refractive, topographic and biomechanical outcomes in patients with progressive keratoconus treated with either conventional or accelerated crosslinking at one year follow up. Methods: It is a prospective, non-randomised interventional study of 76 patients who underwent conventional (CXL; 3mW/cm2 for 30 minutes) or accelerated cross linking (KXL; 30mW/cm2 for 4 minutes) for progressive keratoconus. Baseline and postoperative visual acuity, manifest refraction, corneal topography, pachymetry, endothelial cell density and biomechanical parameters of corneal hysteresis and corneal resistance factor were evaluated and compared. Results: The 2 groups were comparable in terms of uncorrected and best corrected visual acuity and spherical equivalent. Both groups showed no significant increase in K1, K2 and Kmean from baseline at 12 months. There was also no difference between the CXL and KXL group for postoperative corneal topography as well as central and minimal pachymetry up to 12 months. There was a significant increase in both corneal hysteresis (0.62mm Hg, P=0.04) and corneal resistance factor (0.91mm Hg, P=0.003) in the KXL group at 12 months but not in the CXL group. There was no significant endothelial cell loss throughout follow up in both the groups. Conclusion: We have established comparability of the 2 protocols in stabilizing the progression of keratoconus. Our findings also suggested an added biomechanical advantage of accelerated crosslinking at 1 year follow up.

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