scholarly journals 1 year posterior corneal changes after Bowman Layer Transplant for keratoconus

2021 ◽  
pp. 112067212110547
Author(s):  
Abdo Karim Tourkmani ◽  
Conor Lyons ◽  
Parwez N. Hossain ◽  
Aristides Konstantopoulos ◽  
David F. Anderson ◽  
...  
Keyword(s):  
Postoperative Period ◽  
Tertiary Hospital ◽  
Corneal Astigmatism ◽  
Surface Elevation ◽  
Back Surface ◽  
Corneal Surface ◽  
The Uk ◽  
Posterior Corneal Astigmatism

Introduction To report the posterior corneal changes after Bowman Layer Transplant for keratoconus in a tertiary hospital in the UK. Methods 5 eyes of 5 patients receiving Bowman Layer Transplant for advanced keratoconus in Royal Gwent Hospital (Newport, UK) were included. Pre and postoperative posterior corneal astigmatism, posterior Kmean, and back surface elevation were analysed. Results No significant changes were seen in the posterior corneal astigmatism, posterior Kmean, or back surface elevation between the pre- and postoperative period. Conclusion This results would support the idea that the corneal changes seen after Bowman Layer Transplant are mainly in the anterior corneal surface.

scholarly journals Polar Value Analysis of Low to Moderate Astigmatism with Wavefront-Guided Sub-Bowman Keratomileusis

2017 ◽  
Vol 2017 ◽  
pp. 1-9
Author(s):  
Pisong Yan ◽  
Zhiyu Du ◽  
Yu Zhang
Keyword(s):  
Corneal Astigmatism ◽  
Corneal Surface ◽  
Value Analysis ◽  
Surgically Induced Astigmatism ◽  
Induced Astigmatism ◽  
A Minor ◽  
Surgically Induced ◽  
Myopic Astigmatism ◽  
Anterior Corneal Astigmatism ◽  
Posterior Corneal Astigmatism

Purpose. To evaluate the astigmatic outcomes of wavefront-guided sub-Bowman keratomileusis (WFG-SBK) for low to moderate myopic astigmatism.Methods. This study enrolled 100 right eyes from 100 patients who underwent WFG-SBK for the correction of myopia and astigmatism. The polar value method was performed with anterior and posterior corneal astigmatism measured with Scheimpflug camera combined with Placido corneal topography (Sirius, CSO) and refractive astigmatism preoperatively and 1 month, 3 months, and 6 months postoperatively.Results. Similar results for surgically induced astigmatism (SIA) and error of the procedure in both anterior corneal astigmatism (ACA) and total ocular astigmatism (TOA). There was a minor undercorrection of the cylinder in both ACA and TOA. Posterior corneal astigmatism (PCA) showed no significant change.Conclusions. Wavefront-guided SBK could provide good astigmatic outcomes for the correction of low to moderate myopic astigmatism. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after WFG-SBK for myopic astigmatism. Polar value analysis can be used to guide adjustments to the treatment cylinder alongside a nomogram designed to optimize postoperative astigmatic outcomes in myopic WFG-SBK.

scholarly journals Anterior and Posterior Corneal Astigmatism after Refractive Lenticule Extraction for Myopic Astigmatism

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Kazutaka Kamiya ◽  
Kimiya Shimizu ◽  
Mayumi Yamagishi ◽  
Akihito Igarashi ◽  
Hidenaga Kobashi
Keyword(s):  
Corneal Astigmatism ◽  
Rank Test ◽  
Corneal Surface ◽  
Axis Orientation ◽  
Signed Rank ◽  
Signed Rank Test ◽  
Lenticule Extraction ◽  
Myopic Astigmatism ◽  
Anterior Corneal Astigmatism ◽  
Posterior Corneal Astigmatism

Purpose.To assess the amount and the axis orientation of anterior and posterior corneal astigmatism after refractive lenticule extraction (ReLEx) for myopic astigmatism.Methods.We retrospectively examined 53 eyes of 53 consecutive patients (mean age ± standard deviation, 33.2 ± 6.5 years) undergoing ReLEx to correct myopic astigmatism (manifest cylinder = 0.5 diopters (D)). Power vector analysis was performed with anterior and posterior corneal astigmatism measured with a rotating Scheimpflug system (Pentacam HR, Oculus) and refractive astigmatism preoperatively and 3 months postoperatively.Results.Anterior corneal astigmatism was significantly decreased, measuring 1.42 ± 0.73 diopters (D) preoperatively and 1.11 ± 0.53 D postoperatively (p<0.001, Wilcoxon signed-rank test). Posterior corneal astigmatism showed no significant change, falling from 0.44 ± 0.12 D preoperatively to 0.42 ± 0.13 D postoperatively (p=0.18). Refractive astigmatism decreased significantly, from 0.92 ± 0.51 D preoperatively to 0.27 ± 0.44 D postoperatively (p<0.001). The anterior surface showed with-the-rule astigmatism in 51 eyes (96%) preoperatively and 48 eyes (91%) postoperatively. By contrast, the posterior surface showed against-the-rule astigmatism in all eyes preoperatively and postoperatively.Conclusions.The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after ReLEx for myopic astigmatism.

scholarly journals Refractive outcome and tomographic changes after Descemet membrane endothelial keratoplasty in pseudophakic eyes with Fuchs’ endothelial dystrophy

2021 ◽  
Author(s):  
Bishr Agha ◽  
Nura Ahmad ◽  
Daniel G. Dawson ◽  
Thomas Kohnen ◽  
Ingo Schmack
Keyword(s):  
Central Corneal Thickness ◽  
Corneal Thickness ◽  
Corneal Astigmatism ◽  
Endothelial Keratoplasty ◽  
Descemet Membrane Endothelial Keratoplasty ◽  
Corneal Densitometry ◽  
Scheimpflug Imaging ◽  
Fuchs Endothelial Dystrophy ◽  
Posterior Corneal Astigmatism

Abstract Purpose To analyze refractive and topographic changes secondary to Descemet membrane endothelial keratoplasty (DMEK) in pseudophakic eyes with Fuchs’ endothelial dystrophy (FED). Methods Eighty-seven pseudophakic eyes of 74 patients who underwent subsequent DMEK surgery for corneal endothelial decompensation and associated visual impairment were included. Median post-operative follow-up time was 12 months (range: 3–26 months). Main outcome measures were pre- and post-operative manifest refraction, anterior and posterior corneal astigmatism, simulated keratometry (CASimK) and Q value obtained by Scheimpflug imaging. Secondary outcome measures included corrected distance visual acuity (CDVA), central corneal densitometry, central corneal thickness, corneal volume (CV), anterior chamber volume (ACV) and anterior chamber depth (ACD). Results After DMEK surgery, mean pre-operative spherical equivalent (± SD) changed from + 0.04 ± 1.73 D to + 0.37 ± 1.30 D post-operatively (p = 0.06). CDVA, proportion of emmetropic eyes, ACV and ACD increased significantly during follow-up. There was also a significant decrease in posterior corneal astigmatism, central corneal densitometry, central corneal thickness and corneal volume over time (p = 0.001). Only anterior corneal astigmatism and simulated keratometry (CASimK) remained fairly stable after DMEK. Conclusion Despite tendencies toward a hyperopic shift, changes in SE were not significant and refraction remained overall stable in pseudophakic patients undergoing DMEK for FED. Analysis of corneal parameters by Scheimpflug imaging mainly revealed changes in posterior corneal astigmatism pointing out the relevance of posterior corneal profile changes during edema resolution after DMEK.

scholarly journals Does pterygium morphology affect corneal astigmatism?

2021 ◽  
Vol 13 ◽  
pp. 251584142110304
Author(s):  
Emine Doğan ◽  
Burçin Çakır ◽  
Nilgün Aksoy ◽  
Elif Köse ◽  
Gürsoy Alagöz
Keyword(s):  
Anterior Segment ◽  
Clinical Information ◽  
Corneal Astigmatism ◽  
Continuous Group ◽  
Optic Coherence Tomography ◽  
Morphological Pattern ◽  
Horizontal Length ◽  
The Mean ◽  
Anterior Corneal Astigmatism ◽  
Posterior Corneal Astigmatism

Purpose: The purpose of this study was to evaluate the correlation between corneal astigmatism and the morphology of pterygium with anterior segment optic coherence tomography (AS-OCT). Material and Methods: The size of pterygium (horizontal length, vertical width) was measured manually; pterygium area and percentage extension of the pterygium onto the cornea were calculated. Anterior and posterior corneal astigmatism, Sim K, K1, K2 were measured using a dual Scheimpflug analyzer. Morphological patterns of the pterygium analyzed with AS-OCT were determined according to the extension of the pterygium apex below the corneal epithelium. Two tomographic patterns were identified: continuous and nodular. Correlation between anterior corneal astigmatism and pterygium size, percentage extension of the pterygium, and morphological pattern of the pterygium was analyzed. Results: The mean ages of the 47 patients were 49.4 ± 16.6 (22–80) years. Mean horizontal pterygium length, vertical width, pterygium area, and percentage extension of the pterygium were 2.8 ± 1.2 mm, 4.8 ± 1.6 mm, 7.42 ± 5.6 mm2 and 24.5 ± 10.4%, respectively. Mean anterior corneal astigmatism was 2.3 ± 2.3 D and simulated keratometry was 43.4 ± 2.02 D. In terms of the morphological pattern of the pterygium, 24 eyes had continuous, 23 eyes had a nodular pattern and the median (interquartile range) anterior corneal astigmatism was 1.87 (1.01–3.80) and 1.22 D (0.58–2.35), respectively ( p = 0.102). Other topographic and pterygium size parameters were similar between groups. Analyzing the correlations in groups separately, a positive moderate statistically significant correlation was present between vertical width, percentage extension, pterygium area, and anterior corneal astigmatism in both continuous and nodular groups. Conclusions: Although not statistically significant, anterior corneal astigmatism was higher in continuous group. Using AS-OCT to standardize the morphology of pterygium could provide additional clinical information.

scholarly journals Distribution of preoperative and postoperative astigmatism in a large population of patients undergoing cataract surgery in the UK

2018 ◽  
Vol 103 (7) ◽  
pp. 993-1000 ◽  
Author(s):  
Alexander C Day ◽  
Mukesh Dhariwal ◽  
Michael S Keith ◽  
Frank Ender ◽  
Caridad Perez Vives ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Cataract Surgery ◽  
Large Population ◽  
Corneal Astigmatism ◽  
Postoperative Astigmatism ◽  
Before And After ◽  
Significant Burden ◽  
Uk National Health Service ◽  
The Uk ◽  
Refraction Data

PurposeTo assess the prevalence and severity of preoperative and postoperative astigmatism in patients with cataract in the UK.SettingData from 8 UK National Health Service ophthalmology clinics using MediSoft electronic medical records (EMRs).DesignRetrospective cohort study.MethodsEyes from patients aged ≥65 years undergoing cataract surgery were analysed. For all eyes, preoperative (corneal) astigmatism was evaluated using the most recent keratometry measure within 2 years prior to surgery. For eyes receiving standard monofocal intraocular lens (IOLs), postoperative refractive astigmatism was evaluated using the most recent refraction measure within 2–12 months postsurgery. A power vector analysis compared changes in the astigmatic 2-dimensional vector (J0, J45) before and after surgery, for the subgroup of eyes with both preoperative and postoperative astigmatism measurements. Visual acuity was also assessed preoperatively and postoperatively.ResultsEligible eyes included in the analysis were 110 468. Of these, 78% (n=85 650) had preoperative (corneal) astigmatism ≥0.5 dioptres (D), 42% (n=46 003) ≥1.0 D, 21% (n=22 899) ≥1.5 D and 11% (n=11 651) ≥2.0 D. After surgery, the refraction cylinder was available for 39 744 (36%) eyes receiving standard monofocal IOLs, of which 90% (n=35 907) had postoperative astigmatism ≥0.5 D and 58% (n=22 886) ≥1.0 D. Visual acuity tended to worsen postoperatively with increased astigmatism (ρ=−0.44, P<0.01).ConclusionsThere is a significant burden of preoperative astigmatism in the UK cataract population. The available refraction data indicate that this burden is not reduced after surgery with implantation of standard monofocal IOLs. Measures should be taken to improve visual outcomes of patients with astigmatic cataract by simultaneously correcting astigmatism during cataract surgery.

Evaluation of keratoconus progression

2018 ◽  
Vol 103 (4) ◽  
pp. 551-557 ◽  
Author(s):  
Mehdi Shajari ◽  
Gernot Steinwender ◽  
Kim Herrmann ◽  
Kate Barbara Kubiak ◽  
Ivana Pavlovic ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Roc Analysis ◽  
Operating Characteristic ◽  
Characteristic Curve ◽  
Youden Index ◽  
Back Surface ◽  
Corneal Surface ◽  
Maximum Elevation ◽  
Index Index ◽  
Variance Index

AimTo define variables for the evaluation of keratoconus progression and to determine cut-off values.MethodsIn this retrospective cohort study (2010–2016), 265 eyes of 165 patients diagnosed with keratoconus underwent two Scheimpflug measurements (Pentacam) that took place 1 year apart ±3 months. Variables used for keratoconus detection were evaluated for progression and a correlation analysis was performed. By logistic regression analysis, a keratoconus progression index (KPI) was defined. Receiver-operating characteristic curve (ROC) analysis was performed and Youden Index calculated to determine cut-off values.ResultsVariables used for keratoconus detection showed a weak correlation with each other (eg, correlation r=0.245 between RPImin and Kmax, p<0.001). Therefore, we used parameters that took several variables into consideration (eg, D-index, index of surface variance, index for height asymmetry, KPI). KPI was defined by logistic regression and consisted of a Pachymin coefficient of −0.78 (p=0.001), a maximum elevation of back surface coefficient of 0.27 and coefficient of corneal curvature at the zone 3 mm away from the thinnest point on the posterior corneal surface of −12.44 (both p<0.001). The two variables with the highest Youden Index in the ROC analysis were D-index and KPI: D-index had a cut-off of 0.4175 (70.6% sensitivity) and Youden Index of 0.606. Cut-off for KPI was −0.78196 (84.7% sensitivity) and a Youden Index of 0.747; both 90% specificity.ConclusionsKeratoconus progression should be defined by evaluating parameters that consider several corneal changes; we suggest D-index and KPI to detect progression.

Total Corneal Astigmatism and Posterior Corneal Surface

2015 ◽  
Vol 31 (6) ◽  
pp. 423-423
Author(s):  
Virgilio Galvis ◽  
Alejandro Tello ◽  
Camilo A. Niño ◽  
M. Margarita Parra ◽  
Noel Alpins ◽  
...  
Keyword(s):  
Corneal Astigmatism ◽  
Corneal Surface ◽  
Total Corneal Astigmatism
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