Relationship between the corneal surface and the anterior segment of the cornea: An Asian perspective

2006 ◽  
Vol 32 (11) ◽  
pp. 1814-1819 ◽  
Author(s):  
Kooi-Ling Lim ◽  
Han-Bor Fam
Keyword(s):  
Anterior Segment ◽  
Corneal Surface

scholarly journals Impact of Rigid Gas Permeable Contact Lenses Removal on Anterior and Posterior Corneal Surfaces in Keratoconus Patients

2019 ◽  
Author(s):  
Motohiro Itoi ◽  
Koji Kitazawa ◽  
Hisayo Higashihara ◽  
Chie Sotozono
Keyword(s):  
Contact Lens ◽  
Contact Lenses ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Corneal Surface ◽  
Contact Lens Wear ◽  
Surface Areas ◽  
The Impact ◽  
Lens Wear ◽  
Anterior Posterior

AbstractPurposeTo evaluate the impact of removal of rigid gas-permeable (RGP) contact lenses on the anterior and posterior cornea surfaces of eyes with keratoconus.MethodsEight eyes of 8 patients with keratoconus (KC) (age 34.3 ± 15.3 years; range 19–60 years) were enrolled. Anterior segment optical coherence tomography (AS-OCT) was performed at 1, 5, 10, 20, and 60 minutes after the patients removed their RGP contact lenses. Measurements included anterior and posterior best-fit sphere (BFS); elevation values and corneal surface areas; corneal thickness at the thinnest point; and the anterior-posterior ratio of the corneal surface (As/Ps) between 1 minute and 60 minutes after RGP contact lens removal.ResultsAnterior and posterior elevation values and corneal surface areas showed significant increases, whereas anterior and posterior BFS and central corneal thickness decreased significantly (P < 0.01) between 1 minute and 60 minutes after RGP contact lens removal. No statistically significant differences were found in the As/Ps ratio during the first hour after suspending RGP contact lens wear.ConclusionsWe found that the patients with keratoconus experienced significant changes in both the anterior and posterior corneal shape for 60 minutes after removal of RGP contact lenses.

scholarly journals Characteristics of corneal high-order aberrations in adolescents with mild to moderate myopia

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Xu Zhang ◽  
Jin-Hui Ma ◽  
Xin Xi ◽  
Lin Guan
Keyword(s):  
Spherical Aberration ◽  
Anterior Segment ◽  
Corneal Astigmatism ◽  
Surface Shape ◽  
Corneal Surface ◽  
Corneal Aberrations ◽  
Anterior Posterior ◽  
High Order Aberrations ◽  
Posterior Corneal Curvature ◽  
Anterior Corneal Astigmatism

Abstract Background This study investigated the characteristics of corneal higher-order aberrations (HOAs) of the anterior surface, posterior surface, and total cornea in adolescents with mild to moderate myopia. Methods A total of 183 patients with myopia (183 eyes) aged 8 to 18 years were enrolled in this study. The axial length (AL) of the eyes was measured by an IOL-Master, and corneal curvatures (K-values) and HOAs were measured by a Pentacam anterior segment diagnostic analyzer. Results Results of this study showed that the anterior, posterior and total corneal horizontal coma Z31 were − 0.1249 ± 0.105 μm, 0.0009 ± 0.001 μm, and − 0.1331 ± 0.116 μm, respectively; the anterior, posterior and total corneal vertical coma Z3− 1 were − 0.0212 ± 0.164 μm, 0.0003 ± 0.043 μm, and − 0.0216 ± 0.168 μm, respectively; and spherical aberration (SA) Z40 values were 0.2244 ± 0.091 μm, 0.1437 ± 0.029 um, and 0.1889 ± 0.090 μm, respectively. Total corneal Z31 was statistically correlated with posterior corneal astigmatism (K2b − K1b) (p = 0.038). Total corneal Z3− 1 was correlated with anterior corneal astigmatism (K2f − K1f) (p = 0.027). Anterior, posterior, and total corneal Z40 were correlated with anterior and posterior corneal curvature (K1f, K2f, K1b, K2b) (p = 0.001). Posterior corneal Z40b was also significantly correlated with AL. Conclusions In adolescents with mild to moderate myopia, the posterior corneal surface shape may play a compensatory role in the balance of corneal aberrations, and the posterior corneal SA tended to become less negative as the AL increased. The corneal coma may also play a compensatory role in posterior corneal surface astigmatism, which was valuable for the treatment for improving visual quality. This conclusion still needs to be verified.

Accuracy of the indices of MS-39 anterior segment optical coherence tomography in the diagnosis of keratoconic corneas

2021 ◽  
pp. 112067212110637
Author(s):  
Rania S Elkitkat ◽  
Yasser Rifay ◽  
Hesham M Gharieb ◽  
Hossam Eldin A Ziada
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Segment ◽  
Front Surface ◽  
Receiver Operating Curve ◽  
P Value ◽  
Optical Coherence ◽  
Corneal Surface ◽  
Cross Sectional ◽  
The Mean ◽  
Group 2

Purpose To determine the normative and the cut-off values of various indices available in the MS 39 Anterior Segment Optical Coherence Tomography (MS-39 AS-OCT) for keratoconus (KC) diagnosis, and to detect the accuracy of the variable available parameters. Methods This cross sectional observational study was conducted at Dr Rifay Ophthalmology Center, Rabat, Morocco, on 172 eyes with KC (group 1) and 248 eyes of healthy controls (group 2). Participants were screened using MS-39 AS-OCT (CSO, Firenze, Italy). The investigated indices included: keratometric indices, pachymetric indices, elevation indices, Keratoconus Summary Indices (KSI), aberration indices, and epithelial mapping evaluation. Results Most of the studied indices were significantly different between both groups (P value <0.001). Twenty two indices had Area Under the Receiver Operating Curve (AUROC) values >0.950, eight of which were from the KSI. The indices with the highest AUROC values were: Root Mean Square (RMS) for the front corneal surface at 6 mm circle (AUROC = 0.996, and best cut-off >1.69 with sensitivity of 97.67% and specificity of 97.98%) and RMS per unit of area for the front surface at 6 mm circle (AUROC = 0.996, and best cut-off >0.06 with sensitivity of 97.67% and specificity of 97.98%). Epithelial thickness-derived metrics were not among the parameters with the highest accuracy. Conclusions This study presented the mean and the cut-off values for a plethora of parameters available in the MS-39 AS-OCT. The results of this study show that MS-39 AS-OCT is a valuable equipment for diagnosing keratoconic corneas, with a high accuracy detected for many parameters.

scholarly journals Effect of Pterygium Removal Combined with Conjunctival Autograft on Corneal Parameters in Swept-Source Imaging

2022 ◽  
Vol 11 (2) ◽  
pp. 329
Author(s):  
Marta P. Wiącek ◽  
Monika Kuśmierz-Wojtasik ◽  
Bogna Kowalska ◽  
Anna Machalińska
Keyword(s):  
Anterior Segment ◽  
Three Dimensional ◽  
Corneal Topography ◽  
Corneal Surface ◽  
Source Imaging ◽  
Swept Source ◽  
Eye Examination ◽  
Pterygium Excision ◽  
Oct Imaging

Background: Both pterygium ingrowth and excision determine alterations in corneal topography. The aim of this study was to evaluate the influence of pterygium removal combined with conjunctival autografts in addition to the use of human fibrin tissue glue on changes in corneal parameters as measured by 3-D swept-source anterior segment optical coherence tomography (AS-OCT) imaging. Methods: Sixteen eyes (16 patients) with pterygium that qualified for surgical treatment were enrolled in this study. Eye examination, slit lamp, and 3-D AS-OCT (CASIA 2) assessment were performed before the surgery and 7 days, 1 month, and 6 months after pterygium excision. Topographic parameters of both anterior and posterior surfaces of the cornea were analysed at each follow-up visit. Results: The gradual decrease in total astigmatism power from preoperative median 2.75 (6.15) D to 1.2 (1.1) D at 6-month follow-up (p = 0.034) was noted from the day 7 visit. Values were strongly influenced by variations of anterior cornea astigmatism. In contrast, a gradual total HOA reduction at the 1-month (from median 0.79 (1.3) D to 0.44 (0.27) D; p = 0.038) and at 6-month visits (0.25 (0.09); p = 0.001) was observed. Similarly, values were strongly influenced by variations of the anterior. Additionally, total average keratometry values increased from preoperative 44.05 (2.25) D to 44.6 (1.9) (p = 0.043) 1 month after the surgery. Conclusions: Significant steepening of the anterior cornea and a reduction in both astigmatism and HOA were observed after pterygium excision. The anterior corneal surface was an essential component of the total postoperative corneal topography values. Three-dimensional swept-source AS-OCT imaging seems to be a valuable tool for monitoring both the progression of the disease and postoperative effects in pterygium eyes.

Corneal surface area: an index of anterior segment growth

2001 ◽  
Vol 21 (4) ◽  
pp. 286-295 ◽  
Author(s):  
Richard A. Stone ◽  
Ton Lin ◽  
Reiko Sugimoto ◽  
Cheryl Capehart ◽  
Maureen G. Maguire ◽  
...  
Keyword(s):  
Surface Area ◽  
Anterior Segment ◽  
Corneal Surface

scholarly journals Indications for intraoperative anterior segment optical coherence tomography in corneal surgery

2020 ◽  
Vol 40 (10) ◽  
pp. 2617-2625 ◽  
Author(s):  
Stefan J. Lang ◽  
Sonja Heinzelmann ◽  
Daniel Böhringer ◽  
Thomas Reinhard ◽  
Philip Maier
Keyword(s):  
Optical Coherence Tomography ◽  
Penetrating Keratoplasty ◽  
Anterior Segment ◽  
Lamellar Keratoplasty ◽  
Posterior Chamber ◽  
Suture Fixation ◽  
Corneal Surface ◽  
Posterior Chamber Lens ◽  
Transscleral Suture Fixation ◽  
Limbal Transplantation

Abstract Purpose Recently, intraoperative optical coherence tomography (iOCT) has evolved in the field of ophthalmic surgery. So far, the use of iOCT was mainly focused to lamellar keratoplasty, especially deep anterior lamellar keratoplasty (DALK) and Descemet membrane endothelial keratoplasty (DMEK). The aim of this study was to report our experiences with iOCT to introduce new possibilities of this application. Methods We used iOCT in 18 patients who underwent the following surgeries: DALK, DMEK, penetrating keratoplasty, autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens, pannus removal on corneal surface and newborn investigation in Peters’ anomaly. We obtained qualitative video data for all procedures. Results With the iOCT, the cannula placement during DALK preparation of the recipient cornea and bubble formation could be visualized to improve the success rate of the big bubble injection. In DMEK, the iOCT enables the visualization of Descemet’s membrane removal in the recipient and graft orientation as well as better control of graft attachment. The iOCT enables intraoperative visualization of the graft–host interface during penetrating keratoplasty. During autologous limbal transplantation, transscleral suture fixation of a posterior chamber lens and removal of corneal surface pannus the iOCT is capable of showing the thickness of lamellar preparations to avoid penetrations and to save healthy recipient’s tissue. Conclusion The iOCT is a helpful device for intraoperative anterior segment imaging not only for DALK and DMEK. It is also beneficial in penetrating keratoplasty and every other form of lamellar preparation during corneoscleral surgery.

scholarly journals Cellular therapy of corneal epithelial defect by adipose mesenchymal stem cell-derived epithelial progenitors

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Bandeira ◽  
Tze-Wei Goh ◽  
Melina Setiawan ◽  
Gary Hin-Fai Yam ◽  
Jodhbir S. Mehta
Keyword(s):  
Stem Cell ◽  
Growth Factor ◽  
Transforming Growth Factor ◽  
Glycogen Synthase ◽  
Anterior Segment ◽  
Corneal Edema ◽  
Epithelial Differentiation ◽  
Corneal Surface ◽  
Cell Based Therapy ◽  
Epithelial Healing

Abstract Background Persistent epithelial defects (PED), associated with limbal stem cell deficiency (LSCD), require ocular surface reconstruction with a stable corneal epithelium (CE). This study investigated CE reformation using human adipose mesenchymal stem cells (ADSC), which derived epithelial progenitors via mesenchymal-epithelial transition (MET). Methods STEMPRO human ADSC were cultured with specific inhibitors antagonizing glycogen synthase kinase-3 and transforming growth factor-β signaling, followed by culture under a defined progenitor cell targeted-epithelial differentiation condition to generate epithelial-like cells (MET-Epi), which were characterized for cell viability, mesenchymal, and epithelial phenotypes using immunofluorescence and flow cytometry. Tissue-engineered (TE) MET-Epi cells on fibrin gel were transplanted to corneal surface of the rat LSCD model caused by alkali injury. Epithelial healing, corneal edema, and haze grading, CE formation were assessed by fluorescein staining, slit lamp bio-microscopy, anterior segment optical coherence tomography, and immunohistochemistry. Results CD73high/CD90high/CD105high/CD166high/CD14negative/CD31negative human ADSC underwent MET, giving viable epithelial-like progenitors expressing δNp63, CDH1 (E-cadherin), epidermal growth factor receptor, integrin-β4, and cytokeratin (CK)-5, 9. Under defined epithelial differentiation culture, these progenitors generated MET-Epi cells expressing cell junction proteins ZO1 and occludin. When transplanted onto rat corneal surface with LSCD-induced PED, TE-MET-Epi achieved more efficient epithelial healing, suppressed corneal edema, and opacities, when compared to corneas without treatment or transplanted with TE-ADSC. CE markers (CK3, 12, and CDH1) were expressed on TE-MET-Epi-transplanted corneas but not in other control groups. Conclusion Human ADSC-derived epithelial-like cells, via MET, recovered the CE from PED associated with LSCD. ADSC can be a viable adult stem cell source for potential autologous epithelial cell-based therapy for corneal surface disorders.

Corneal tomographic changes during corneal rigid gas-permeable contact lens wear in keratoconic eyes

2020 ◽  
pp. bjophthalmol-2020-317057
Author(s):  
Shizuka Koh ◽  
Ryota Inoue ◽  
Naoyuki Maeda ◽  
Yoshinori Oie ◽  
Vishal Jhanji ◽  
...  
Keyword(s):  
Contact Lenses ◽  
Amplitude Ratio ◽  
Anterior Segment ◽  
Three Dimensional ◽  
Biomechanical Properties ◽  
Corneal Surface ◽  
Surface Flattening ◽  
Contact Lens Wear ◽  
Fourier Harmonic ◽  
The Difference

Background/AimsWe aimed to investigate the refractive changes in the posterior corneal surface in keratoconus (KC) associated with wearing spherical corneal rigid gas-permeable contact lenses (corneal GPs) with apical touch or three-point touch fitting and the effect of spherical corneal GPs on corneal biomechanics.MethodsPatients with KC wearing corneal GPs every day without facing complications were enrolled as a single group. Corneal tomographic data were obtained using a three-dimensional anterior segment optical coherence tomography from the same eye with and without corneal GPs. Dioptric data from the central 3-mm zone of the posterior corneal surface were decomposed into spherical, regular astigmatism, asymmetry and higher-order irregularity components using Fourier harmonic analysis. The corneal biomechanical indices were deformation amplitude ratio within 2 mm, integrated radius, stiffness parameter at first applanation and linear Corvis Biomechanical Index. Correlations between the difference in Fourier indices with and without corneal GPs and the corneal biomechanical parameters were analysed.ResultsThirty-two eyes of 32 patients with KC were enrolled. Spherical, regular astigmatism and asymmetry components were significantly smaller with corneal GP wear than without the wear (all p<0.001). All biomechanical indices were significantly correlated with the difference in the spherical components with and without corneal GPs.ConclusionCorneal biomechanical properties of KC were correlated with posterior corneal surface flattening induced by wearing corneal GPs on the spherical components. This effect is greater in biomechanically weaker corneas.

scholarly journals Comparison of anterior segment changes after femtosecond laser LASIK and SMILE using a dual rotating Scheimpflug analyzer

2019 ◽  
Author(s):  
Bu Ki Kim ◽  
Su Joung Mun ◽  
Young Hoon Yang ◽  
Ji Sun Kim ◽  
Jun Hyung Moon ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Laser In Situ Keratomileusis ◽  
Corneal Surface ◽  
Significant Difference ◽  
Sphere Radius ◽  
Lenticule Extraction

Abstract Purpose To compare the changes in the anterior segment after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) using a dual rotating Scheimpflug (DRS) analyzer (Galilei®; Ziemer Ophthalmology, Port, Switzerland). Setting Onnuri smile eye clinic, Seoul, South Korea Design Retrospective Method 218 eyes of 109 patients who underwent FS-LASIK or SMILE for myopic correction were retrospectively studied. Ninety-eight eyes of 49 patients who underwent FS-LASIK were compared to 120 eyes of 60 patients treated with SMILE. A DRS analyzer was used for preoperative and 6-month postoperative anterior segment analyses. Measured variables included the central corneal thickness (CCT), anterior chamber depth (ACD), anterior and posterior keratometry (K), anterior and posterior best-fit sphere radius, and maximum posterior elevation (MPE). Results The estimated lenticule thickness (LT; 87.20 ± 22.87 µm) was significantly thicker in the SMILE group than the ablation depth (69.23 ± 22.24 µm) in the FS-LASIK group. However, there was no significant difference in the CCT decrease using the DRS analyzer. The MPE was significantly increased after both procedures, and there was a statistically significant difference in the change in MPE between the two groups (-1.10 ± 2.12 µm after FS-LASIK; -0.75 ± 2.33 µm after SMILE; p = 0.035). Conclusions The preoperative LT was overestimated using SMILE. Regarding changes in the MPE and posterior K, changes in the posterior corneal surface were greater after FS-LASIK than after SMILE.

scholarly journals Comparison of anterior segment changes after femtosecond laser LASIK and SMILE using a dual rotating Scheimpflug analyzer

2019 ◽  
Author(s):  
Bu Ki Kim ◽  
Su Joung Mun ◽  
Young Hoon Yang ◽  
Ji Sun Kim ◽  
Jun Hyung Moon ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Laser In Situ Keratomileusis ◽  
Corneal Surface ◽  
Sphere Radius ◽  
Lenticule Extraction ◽  
Best Fit

Abstract Background: To compare the changes in the anterior segment after femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) using a dual rotating Scheimpflug (DRS) analyzer (Galilei®; Ziemer Ophthalmology, Port, Switzerland).Methods: A total of 218 eyes of 109 patients who underwent FS-LASIK or SMILE for myopic correction were retrospectively studied. Ninety-eight eyes of 49 patients who underwent FS-LASIK were compared to 120 eyes of 60 patients treated with SMILE. A DRS analyzer was used for preoperative and 6-month postoperative anterior segment analyses. Measured variables included the central corneal thickness (CCT), anterior chamber depth (ACD), anterior and posterior keratometry (K), anterior and posterior best-fit sphere radius, and maximum posterior elevation (MPE).Results: After the procedure, the amount of CCT decrease was higher in the SMILE group than in the FS-LASIK group, but it was not statistically significant. The MPE was significantly increased after both procedures (p < 0.001 and p = 0.001 in the FS-LASIK and SMILE groups, respectively), with the amount of elevation being higher after FS-LASIK than after SMILE even though it was not statistically significant. And there was a significant change in the steep and average posterior K in the FS-LASIK group (p = 0.006 and 0.001, respectively), but not in the SMILE group.Conclusions: Regarding changes in the MPE and posterior K, changes in the posterior corneal surface were greater after FS-LASIK than after SMILE.

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