Epithelial and stromal thickness profile and lens decentration in myopic orthokeratology / Perfil de espesor epitelial y estromal y descentrado del cristalino en ortoqueratología miope

Purpose: To study topographic epithelial and total corneal thickness changes in myopic subjects undergoing successful orthokeratology treatment in connection with the objective assessment of contact lens decentration. Methods: A prospective-observational and non-randomized study in 32 Caucasian myopic eyes undergoing Ortho-k for 3 months. Total, epithelial, and stromal thicknesses were studied before and after Ortho-k treatment, using optical coherence tomography with anterior segment application software. Central, paracentral, and mid-peripheral values are taken along 8 semi-meridians. Results: The central average total corneal thickness was 4.72 ± 1.04 μm thinner after Ortho-K. The paracentral corneal thickness showed no significant changes (p = 0.137), while the mid-peripheral corneal thickness was increased by 3.25 ± 1.6 μm associating this increase exclusively to the epithelial plot (p<0.001). When lens centration was assessed, a lens fitting decentration less than 1.0 mm was found for the whole sample, predominantly horizontal-temporal (87.5%) and vertical-inferior (50%) decentring. Corneal topographical analysis revealed a horizontal and vertical epithelial thickness asymmetric change profile with paracentral temporal thinnest values, and mid-peripheral nasal thickest values. Conclusions: The present study found a central corneal thinning induced by Ortho-k lenses in subjects with moderate myopia, only associated with a change in epithelial thickness, as well as mid-peripheral thickening, that seems to be mainly epithelial in origin. The authors also found a tendency of contact lens decentration toward temporal and inferior areas conditioning an asymmetric epithelial redistribution pattern.(AU)

Corneal Epithelial Changes in Diabetic Patients: A Review.

The relationship between diabetes mellitus and ocular complications has been extensively studied by many authors. Diabetic keratopathy has already been well characterized and defined as a clinical entity. This review focuses on exploring corneal epithelial changes in diabetic patients, aiming to provide a pragmatic overview of the existing knowledge on this topic. The paper systematically examines alterations in corneal epithelial structure and their impact on diabetic patients. Advanced imaging techniques are also discussed for their role in precise characterization and improved diagnostics. Additionally, the paper explores the mechanisms behind corneal epithelial changes in diabetes, looking at factors such as hyperglycemia, oxidative stress, and Advanced Glycation End-Products. The impact of altered corneal epithelial integrity on barrier function and susceptibility to external issues is considered, addressing potential links to heightened proteolytic enzyme activities and delayed wound healing observed in diabetic individuals. The review also covers the practical implications of corneal epithelial changes, including the association with corneal erosions, persistent epithelial defects, and an increased risk of dry eye syndrome in diabetic patients.

Evaluation of dry eye disease and corneal epithelial mapping in patients with lower eyelid ectropion.

PURPOSE: To evaluate the corneal epithelial mapping, ocular surface parameters and their relationship with each other in lower eyelid ectropion patients according to severity. METHODS: This retrospective study included 48 lower eyelid ectropion patients and 63 healthy individuals as control group. Ocular surface and tear functions were evaluated with ocular surface staining score, tear film break-up time (BUT), non-invasive tear break-up time (NIBUT) and ocular surface disease index (OSDI). Meibography scores and corneal epithelial thickness (CET) mapping were evaluated. The lower eyelid ectropion was classified and divided into subgroups as follows: mild, moderate and severe. RESULTS: There was no significant differences between the groups for age and gender. Compared to controls, CET was significantly thinner at inferior (p = 0.047) and inferior nasal quadrants (p = 0.023) in the ectropion patients. Lower BUT and NIBUT, higher OSDI scores and higher ocular surface staining were observed in the ectropion patients. In the subgroups determined according to the severity of ectropion, ocular surface damage was found to be significantly higher as the severity of ectropion increased (p < 0.05). CONCLUSION: Patients with lower eyelid ectropion had worse ocular surface findings and more ocular complaints. Furthermore, the inferior and inferior nasal CETs were thinner in patients with lower ectropion.

A comparison of conventional and accelerated corneal crosslinking: corneal epithelial remodeling and in vivo confocal microscopy analysis.

PURPOSE: To evaluate the effect of conventional and accelerated corneal crosslinking (CXL) on visual acuity, corneal topography, corneal epithelial thickness, and subbasal nerve morphology in progressive keratoconus patients. METHODS: In this prospective and randomized study, twenty eyes of 20 patients were treated with conventional CXL (3 mW/cm2, 30 min, C-CXL) and 19 eyes of 19 patients were treated with accelerated CXL (9 mW/cm2, 10 min, A-CXL). The spherical equivalent, uncorrected visual acuity, best-corrected visual acuity, keratometric measurements, demarcation line measurement and epithelial thickness mapping analyses, and subbasal nerve morphology with in vivo confocal microscopy (IVCCM) were evaluated at baseline and at postoperative months 1, 3 and 6. RESULTS: At postoperative 6 months, a significant improvement was observed in all keratometric values in both treatment groups (p < 0.05). All epithelial thickness indices, except central, temporal, and inferotemporal thickness, were reduced at 1 month postoperatively in both treatment groups. The epithelial map uniformity indices (standard deviation and difference between min-max thickness) were significantly lower than the baseline values at all time points after CXL in both treatment groups (p < 0.001). Compared with the preoperative values, there was a significant decrease in all IVCCM parameters at 1 month postoperatively (p < 0.05). At 6 months postoperatively, corneal nerve fiber density and corneal nerve branch density recovered to preoperative values in the A-CXL group, whereas corneal nerve regeneration was not complete in the C-CXL group. CONCLUSION: Both conventional and accelerated CXL treatments appear to be effective in halting the progression of KC. Corneal epithelial irregularity slightly improves after CXL. The regeneration of subbasal nerves is faster after A-CXL treatment.

Investigation of corneal epithelial thickness and irregularity by optical coherence tomography after transepithelial photorefractive keratectomy.

CLINICAL RELEVANCE: Corneal epithelial healing after refractive surgery is a clinically significant issue, especially for surface ablation procedures, and this can be monitored using optical coherence tomography (OCT). BACKGROUND: The aim of this work is to investigate the corneal epithelial thickness and irregularity by OCT after transepithelial photorefractive keratectomy (t-PRK) and analyse its correlation with visual and refractive outcomes. METHODS: Patients aged ≥18 years with myopia, with or without astigmatism, who underwent t-PRK between May 2020 and August 2021 were included. All participants were subjected to complete ophthalmic examinations and OCT pachymetry at every follow-up visit. Patients were followed up at 1 week and 1, 3, and 6 months postoperatively. RESULTS: A total of 67 patients (126 eyes) were enrolled in this study. One month postoperatively, spherical equivalent refraction and visual acuity achieved preliminary stability. However, central corneal epithelial thickness (CCET) and standard deviation of the corneal epithelial thickness (SDcet) took 3-6 months to progressive recovery. Patients with higher baseline spherical equivalent refraction were associated with slower epithelial recovery. At every follow-up time point, a significant superior-inferior difference in the minimum corneal epithelial thickness area was observed. Higher stromal haze was correlated with higher spherical equivalent refraction (both baseline and residual) but had no relation with visual outcomes. There was a significant correlation between higher CCET with a better uncorrected distance visual acuity and lower corneal epithelial thickness irregularity. CONCLUSIONS: CCET and SDcet measured by OCT seem to be a good auxiliary indicator for reflecting the status of corneal wound recovery after t-PRK surgery. However, a well-designed randomised control study is needed to confirm the study results.

Comparative evaluation of corneal and limbal epithelial thickness in brachycephalic dogs with and without corneal diseases using spectral domain optical coherence tomography.

OBJECTIVE: To evaluate alterations in epithelial thickness during corneal degeneration, corneal pigmentation, and additional features observed through spectral-domain optical coherence tomography (SD-OCT) in brachycephalic dogs. ANIMALS AND PROCEDURES: The study used 55 eyes from 49 brachycephalic dogs that underwent OCT-containing ophthalmic examinations. The examined eyes were classified into corneal degeneration, corneal pigmentation, and normal groups according to corneal lesions. For each eye, corneal epithelial thickness (CET) in the central cornea and maximum limbal epithelial thickness (maxLET) in 4 quadrants of limbus (superior, inferior, nasal, and temporal) were measured from OCT images. Additional abnormal findings on OCT images, including irregular epithelium, subepithelial hyperreflectivity, and conjunctivochalasis, were also recorded. RESULTS: The corneal degeneration group had significantly thinner nasal and temporal maxLETs than that of the normal group (p < .001). In the central corneal OCT image of the corneal degeneration group, an irregular epithelium was observed in 70.6% and subepithelial hyperreflectivity in 82.4%, both of which were significantly higher than the normal group (p < .001). In a comparative analysis, the nasal, temporal, and inferior maxLETs were significantly thinner in the corneal pigmentation group than those in the normal group (p < .001, p < .001, and p = .01, respectively). CONCLUSIONS: Morphological changes in the limbal epithelium were observed in dogs with corneal degeneration and corneal pigmentation. LET reduction could be associated with their pathogenesis and would be valuable as an additional parameter for corneal diseases.

The Effect of Upper Eyelid Blepharoplasty on Corneal Tomography and Epithelial Profile.

Introduction: Upper tarsal mechanical forces influence corneal epithelial thickness profile, which could modulate corneal astigmatism. Upper eyelid blepharoplasty reduces upper tarsal strength and may have an impact on ocular surface. The aim of this study is to evaluate the effect of upper eyelid blepharoplasty on corneal epithelial thickness profile, astigmatism and aberrations. Methods: Patients with dermatochalasis underwent bilateral upper eyelid blepharoplasty. Anterior segment optical coherence tomography (AS-OCT) (Zeiss Cirrus 5000 HD-OCT) and Pentacam (Oculus, Wetzlar Germany) were performed before surgery and in the 8th postoperative week. Corneal epithelial thickness, keratometry, aberrations and asphericity were considered for statistical purposes. Only right eyes were considered. A p-value lower than 0.05 was considered significant. Results: Thirty eyes of 30 patients were included. The degree of astigmatism did not change after surgery (0.95D vs 0.83D, p=0.23). The difference between preoperative and postoperative steepest axis was 3.1° (p=0.04) with a tendency to change toward the vertical meridian. Mean epithelial thickness was higher in the inferior region both pre- and postoperatively and did not change. ET in the superior octant was lower (42 µm vs 45 µm, p<0.01) and the difference between inferior and superior octants (I-S) was higher (7 µm vs 3 µm, p<0.001) before surgery. There were no statistically significant changes in corneal aberrations (p=0.52) and asphericity (p=0.41) after surgery. Conclusion: Our results support that upper tarsus pressure influences epithelial thickness profile and, consequently, the corneal steepest keratometry. These results lead us to postulate that upper eyelid blepharoplasty may influence biometric and keratometric measurements.

Compensatory Corneal Epithelial Changes After Femtolaser - Assisted Intracorneal Rings Implantation in Early and Moderate Cases of Keratoconus.

Purpose: To study the compensatory corneal epithelial changes after femtolaser-assisted intracorneal ring segment (ICRS) implantation in early and moderate cases of keratoconus (KC) using anterior segment optical coherence tomography (AS-OCT). Patients and Methods: A prospective observational non-randomized study of 40 eyes with mild to moderate KC received femtolaser-assisted ICRS implantation. Ferrara ICRS with different arc lengths and thicknesses were used according to the patients' tomographic pattern. Patients had a clear central cornea, keratometry reading < 60 diopters, and corneal thickness > 400 microns. AS-OCT was performed preoperatively and at 1, 3, and 6 months after surgery. Corneal epithelial thickness (CET) was measured over 17 points (2 mm central and 16 points on 2-5 mm and 5-7 mm annular zones) over the pupil center. All data were collected and analyzed. Results: Comparing the preoperative and postoperative data, there was a statistically significant increase in the CET postoperatively throughout the 6-month follow-up period in all zones (p<0.001). The epithelial thickness (ET) was noticed shortly around and central to the ring ridges by the first month (5-7 mm zone). By the third month, the flattened central cornea (2 mm zone) and the 2-5 mm zone showed a significant increase in ET up to the 6th month. Conclusion: ICRS implantation in KC results in a thicker and more regular epithelium in the central corneal zone as a secondary response to the corneal stromal changes induced by the implants.

The effect of CO2 laser therapy on vaginal microcirculatory parameters in an animal model for genitourinary syndrome of menopause.

BACKGROUND: Vaginal laser therapy for the treatment of genitourinary syndrome of menopause (GSM) has been introduced to the market with limited (pre)clinical and experimental evidence supporting its efficacy. It is suggested that vaginal laser therapy increases epithelial thickness and improves vascularization, but the underlying biological working mechanism has not been substantiated yet. OBJECTIVE: To evaluate the effects of CO2 laser therapy on vaginal atrophy using noninvasive incident dark field (IDF) imaging in a large animal model for GSM. DESIGN, SETTING, AND PARTICIPANTS: An animal study was conducted between 2018 and 2019 and included 25 Dohne Merino ewes, of which 20 underwent bilateral ovariectomy (OVX) to induce iatrogenic menopause, and 5 did not. The total study duration was 10 months. INTERVENTIONS: Five months after OVX, ovariectomized ewes received monthly applications of CO2 laser (n = 7), vaginal estrogen (n = 7), or no treatment (n = 6) for 3 months. IDF imaging was performed monthly in all animals. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The primary outcome was the proportion of image sequences containing capillary loops (angioarchitecture). Secondary outcomes included focal depth (epithelial thickness), and quantitative measures of vessel density and perfusion. Treatment effects were evaluated using ANCOVA and binary logistic regression. RESULTS AND LIMITATIONS: Compared to OVX-only, ewes treated with estrogen demonstrated a higher capillary loops proportion (4% vs. 75%, p < 0.01), and higher focal depth (60 (IQR 60-80) vs. 80 (IQR 80-80) p < 0.05). CO2 laser therapy did not change microcirculatory parameters. As the ewes' vaginal epithelium is thinner than that of humans, it may demand different laser settings. CONCLUSIONS: In a large animal model for GSM, CO2 laser therapy does not affect microcirculatory outcomes related to GSM, whereas vaginal estrogen treatment does. Until more homogeneous and objective evidence about its efficacy is available, CO2 laser therapy should not be adopted into widespread practice for treating GSM.

Descemet Membrane Endothelial Keratoplasty (DMEK) Reduces the Corneal Epithelial Thickness in Fuchs' Patients.

Fuchs' endothelial corneal dystrophy (FECD) is the occurrence of corneal edema due to endothelial cell dystrophy. Descemet membrane endothelial keratoplasty (DMEK) is considered to be the gold standard of treatment. The aim of this study was to investigate the changes in the corneal epithelial thickness of FECD patients before and after DMEK and to compare these results with a healthy control cohort. In this retrospective analysis, 38 eyes of patients with FECD that were treated with DMEK and 35 healthy control eyes received anterior segment optical coherence tomography (OCT; Optovue, XR-Avanti, Fremont, CA, USA). The corneal epithelial thicknesses in different locations were analyzed and compared between the preoperative, postoperative, and control cohorts. The median follow-up time was 9 months. There was a significant degression of the mean epithelial thickness after DMEK in the central, paracentral, and mid-peripheral zones (p < 0.01) of the cornea. The total corneal thickness and stromal thickness decreased significantly as well. No significant differences were observed between the postoperative and control cohorts. In conclusion, the FECD patients had an increased epithelial thickness compared to the healthy controls, which decreased significantly after DMEK and reached thickness levels comparable to those of healthy control eyes. This study emphasized the importance of distinguishing between the corneal layers in anterior segment pathologies and surgical procedures. Moreover, it accentuated the fact that the structural alterations in FECD extend beyond the corneal stroma.

Repeatability of corneal pachymetry and epithelial thickness measurements with spectral-domain optical coherence tomography (SD-OCT) and correlation to ocular surface parameters.

PURPOSE: To assess the repeatability of corneal pachymetry and epithelial thickness measurements with spectral-domain optical coherence tomography (SD-OCT) and identify correlations between epithelial thickness and ocular surface parameters. METHODS: Adults who happened to have prolonged computer use were recruited, excluding those with conditions interfering with corneal measurements or tear production. All subjects filled in the ocular surface disease index (OSDI) questionnaire. Three consecutive measurements of central and peripheral corneal and epithelial thickness were performed with SD-OCT (RTVue XR). Schirmer test I and tear film break-up time (TBUT) were performed. Repeatability was evaluated with intraclass correlation coefficient (ICC), coefficient of variation and repeatability limit. Spearman correlation was used for non-parametric variables. RESULTS: 113 eyes of 63 subjects were included in the study. ICC was ≥ 0.989 for all corneal and ≥ 0.944 for all epithelial pachymetry segments. The best repeatability was found centrally and the worst superiorly both for corneal and epithelial measurements. Central epithelial thickness was weakly correlated with Schirmer test I (rho = 0.21), TBUT (rho = 0.02), OSDI symptoms and OSDI score (rho <|0.32|). OSDI symptoms and OSDI score were weakly correlated with Schirmer test I (rho <|0.3|) and TBUT (rho <|0.34|). CONCLUSION: RTVue XR measurements of corneal and epithelial thickness are highly repeatable in all segments. The lack of correlation between epithelial thickness and ocular surface parameters could suggest the assessment of epithelial integrity with reliable methods such as SD-OCT.

Corneal Epithelial Thickness Changes After Topical Treatment of Dry Eye Disease in Primary Sjögren Syndrome.

Purpose: To evaluate the changes on epithelial thickness before and after topical treatment in primary Sjögren syndrome-associated dry eye disease (SS-DED). Methods: This was a prospective study that included referred women with SS-DED and healthy age-matched controls. Corneal epithelial thickness was evaluated using high-definition anterior segment optical coherence tomography (Cirrus 5000 HD-OCT) in the baseline first consultation, and four weeks after treatment with preservative free 1mg/1mL sodium hyaluronate. Schirmer test 1 (ST1), tear break-up time (TBUT), tear meniscus height (TMH), SICCA Ocular Surface Score (SICCA OSS) and Ocular Surface Disease Index (OSDI) were evaluated. Statistical significance was defined as p-value <0.05. Results: The study included 40 eyes, 20 with SS-DED and 20 controls. At baseline, SS-DED patients had lower ST1 (11.1 ± 2.2mm vs 14.1 ± 3.1mm, p<0.01), faster TBUT (9.1 ± 1.8s vs 13.2 ± 1.1s, p<0.01) and lower TMH (211.2 ± 68.4 µm vs 217.2 ± 60.1µm; p<0.01) than the control group, whereas SICCA OSS and OSDI were higher (p<0.01). The superior epithelium was thinner in SS-DED group (41.1 ± 3.2 µm vs 43.1± 2.3 µm, p<0.01). After treatment, ST1, TBUT, TMH, SICCA OSS, and OSDI improved (p<0.01), and superior epithelium thickened (p<0.01) in the SS-DED group. Conclusion: Treatment with sodium hyaluronate improved ST1, TBUT, TMH, SICCA-OSS, and OSDI score. Superior epithelium tends to be thinner in SS-DED but becomes thicker with treatment. Our results seem to illustrate the morphological changes in the corneal epithelium in DED, which could be further recognized as a clinical biomarker of SS-DED.

How Can We Diagnose Ocular Surface Squamous Neoplasia With Optical Coherence Tomography?

AIM: We aimed to evaluate the effectiveness of optical coherence tomography (OCT) in the differential diagnosis of anterior segment diseases such as ocular surface squamous neoplasia (OSSN) and pterygium. METHODS: Patients who were pre-diagnosed with either OSSN (21) or pterygium (19) between January 2020 and November 2022 were included in this retrospective study. Anterior segment photographs and anterior segment optical coherence tomography (AS-OCT) measurements were obtained from each patient. Excisional or incisional biopsy materials underwent pathological evaluation. RESULTS: Preoperative AS-OCT images of the patients with OSSN showed similarities with histopathological specimens. Both ocular and pathological specimens appeared to have a thicker epithelial layer with a distinct change from healthy to neoplastic epithelium. Preoperative AS-OCT images of individuals with pterygium were also comparable with histopathological samples. Both pathological and AS-OCT images of the pterygium patients showed a normal thickness epithelium and a thickened subepithelial layer under the epithelium. The mean epithelial thickness measured with AS-OCT in OSSN patients was found to be 295.3 ± 111.3 µm, while it was 80.7 ± 43.4 µm in pterygium patients. The difference was statistically significant (P<0.001). The receiver operating characteristic (ROC) curve analysis revealed a cut-off value of 97 µm for the differential diagnosis of OSSN from pterygium, with a sensitivity of 100% and specificity of 94.7%. CONCLUSIONS: AS-OCT can be used as a noninvasive diagnostic tool for the evaluation of ocular surface lesions. Its ability to distinguish between OSSN and pterygium is demonstrated by the statistically significant difference in epithelial thickness and the significant morphological association with histopathological findings.

Evaluation of central corneal epithelial thickness with anterior segment OCT in patients with type 2 diabetes mellitus.

BACKGROUND: This study aimed to evaluate the central corneal thickness (CCT) and central corneal epithelial thickness (CCET) in patients with Type 2 diabetes mellitus (DM), and the effect of the duration of diabetes, the degree of diabetic retinopathy (DR), and HbA1c level. METHODS: CCT and CCET values of 72 patients diagnosed with type 2 DM and 72 healthy individuals were measured by anterior segment optical coherence tomography. The eye tear function was evaluated with the Tear Break-up Time test (TBUT) and the Schirmer test. From the results of fundus examination, the diabetic patients were grouped as those without DR, non-proliferative DR, and proliferative DR. The disease duration and the HbA1c levels were recorded. RESULTS: In the diabetic patients, the mean CCT was determined to be thicker (p = 0.025), the CCET was thinner (p = 0.003), and the TBUT and Schirmer values were lower (p <0.001, p <0.001, respectively). The duration of diabetes and the HbA1c level was not found to have any statistically significant effect on these parameters (p >0.05). The presence of retinopathy had no significant effect on CCT, TBUT, and Schirmer values. The CCET was determined to be thinner in patients with retinopathy (p <0.001). CONCLUSIONS: As the corneal epithelial thickness is reduced in patients with advanced diabetic retinopathy, corneal epithelial pathologies can be seen more often. Therefore, early and effective treatment can be started by taking into consideration the complications which may develop associated with the corneal epithelium following surgical procedures, especially those applied to the cornea.

Assessment of corneal and limbal epithelial thickness by spectral-domain optical coherence tomography in brachycephalic and non-brachycephalic dogs.

OBJECTIVE: To investigate the variance in corneal epithelial thickness (CET) and limbal epithelial thickness (LET) according to the age and skull type by using spectral-domain optical coherence tomography (SD-OCT) in normal dogs. ANIMALS AND PROCEDURES: This study used an eye each from 46 dogs (24 brachycephalic and 22 non-brachycephalic dogs) assessed to have clear corneas. Each dog was classified according to age into groups 1 (0-5 years), 2 (6-10 years), and 3 (>11 years). OCT imaging was performed on the central cornea for CET and perpendicular to the quadrant of the limbus for LET. The average of the maximum LET (maxLET) value was measured in four eye quadrants. RESULTS: Corneal epithelial thickness was not significantly different according to age in brachycephalic and non-brachycephalic dogs. Visualization of the limbal invagination was better when the maxLET was thick. Nasal and temporal maxLETs were significantly thicker than superior and inferior maxLETs in non-brachycephalic dogs. In brachycephalic dogs, there was a significant decrease in nasal maxLET with age (rs  = -0.489, p = .015). Significant differences between brachycephalic and non-brachycephalic dogs were observed in nasal maxLET (p = .024) and temporal maxLET (p = .011). CONCLUSIONS: Invagination was better visualized in the nasal and temporal limbal quadrants of non-brachycephalic dogs compared with brachycephalic dogs, and the maxLETs of the regions were thicker than those of the brachycephalic dogs. CET and LET measurements using SD-OCT can help in clinical assessment and research on ocular surface diseases in dogs.

Evaluation of the Effect of Dermatochalasis and Upper Eyelid Blepharoplasty Surgery on Corneal Epithelial Thickness Alterations.

BACKGROUND: The aim of this study was to assess the effect of different grades of dermatochalasis (DC) and upper eyelid blepharoplasty (UEB) surgery on corneal epithelial thickness (CET), objectively using anterior segment-optical coherence tomography (AS-OCT) measurements. METHODS: 90 eyes of patients with DC were divided into three groups according to the severity of the DC. Forty-one eyes of age and sex-matched patients without DC were randomly selected as the control group. The study did not include patients with more than 2 D of spherical refractive error and more than 1.5 D of astigmatism, a history of previous eyelid surgery, ocular surface disease, contact lens use, and ophthalmic eye drop use. CET measurements of all the patients were performed with an AS-OCT (RTVue-XR, Optovue Inc., USA). RESULTS: There were statistically significant differences in the CET of the superior, superonasal, superotemporal, inferotemporal, and temporal sectors between the DC and control groups (p = 0.001, p = 0.02, p = 0.03, p = 0.02, p = 0.04, respectively). While there were no differences in CET among the sectors of the control group, there was a difference in CET among some sectors of the DC group. When the DC group was subdivided by severity, there was no difference between subgroups for CET across all sectors both preoperatively and postoperatively. In the measurements made 6 months after UEB surgery, the CET in all sectors increased statistically significantly compared to those measured in the preoperative period. CONCLUSION: This study revealed that DC reshaped the corneal epithelium and UEB surgery restored this remodeling 6 months after surgery. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Evaluation of corneal epithelial thickness mapping using anterior segment OCT in children with vernal keratoconjunctivitis.

PURPOSE: To evaluate the corneal epithelial thickness by anterior segment OCT in children with vernal keratoconjunctivitis (VKC) compared to normal participants. PATIENT AND METHODS: A cross-sectional case control observational study was conducted on children aged from 5 to 18 years with VKC. The study included 142 eyes divided into two groups: 71 eyes of VKC group and 71 eyes of age matched control group. Anterior segment OCT epithelial mapping for the central 5-mm was done to evaluate epithelial thickness-based variables. RESULTS: Corneal epithelial thickness mapping showed significant superior thinning (51.07 ± 4.11) µm in VKC group compared to controls (52.54 ± 2.01) µm (p = 0.008), a decreased MIN epithelial thickness (45.99 ± 6.52) µm compared to controls (50.11 ± 1.91) µm (p < 0.001) and more negative (MIN-MAX) value (- 11.77 ± 9.38) indicating focal epithelial thinning compared to (- 5.80 ± 1.88) in controls (p = 0.001). In palpebral VKC, MIN epithelial thickness showed significant thinning (48. 38 ± 3.45) µm compared to controls (50.11 ± 1.91) µm (p = 0.001). Eyes with mixed VKC showed superior epithelial thinning (50.70 ± 4.59) µm compared to (52.54 ± 2.01) µm in controls (p = 0.025) and significant decreased MIN epithelial thickness (43.78 ± 7.83) µm compared to (50.11 ± 1.91) µm in control group. CONCLUSIONS: VKC is a disease primarily affecting the corneal epithelium. Corneal epithelial thickness mapping may be considered to assess the integrity of the ocular surface in eyes with VKC, and to detect corneal epithelial changes. Disease phenotype may influence the corneal epithelial changes, and the disease duration is another factor influencing these changes.

The effect of incomplete blinking rate on corneal epithelial remodeling after trans-PRK surgery: a six-month study.

Purpose: To evaluate the impact of incomplete blink rate on corneal epithelial thickness after transepithelial photorefractive keratectomy (Trans-PRK) surgery. Methods: Trans-PRK patients were divided into two groups based on preoperative incomplete blinking rates, namely rates ≤0.5 (41 right eyes, group A) and rates >0.5 (65 right eyes, group B). We used anterior segment optical coherence tomography to measure the corneal epithelial thickness (CET) and lipiview to measure the number of blinks, incomplete blinking rate, and lipid layer thickness (LLT). Results: In both groups, CET decreased at 1 week and 1 month, and the thicknesses in the IT, T, and ST regions exceeded the preoperative levels. Three months after Trans-PRK, the thickness exceeded the preoperative levels and continued to increase during subsequent follow-ups. The blinking times and LLT in both groups decreased at 1 week and gradually increased but did not return to preoperative levels. Group A maintained an incomplete blinking rate of over 0.5 at all postoperative periods. The incomplete blinking rate of group B remained above 0.5 postoperatively, although there was an improvement compared with preoperative rates. Both groups showed a correlation between changes in CET and incomplete blinking rate. There was a correlation between changes in LLT and the incomplete blinking rate after surgery. Conclusion: Both groups showed uneven corneal epithelia thickening, which became more pronounced approaching the peripheral areas. In addition, changes in CET after surgery were positively correlated with the incomplete blinking rate in both patient groups. There was a negative correlation between postoperative LLT and incomplete blinking rate.

Corneal epithelial remodeling following stromal lenticule addition keratoplasty combined with corneal collagen cross-linking for the treatment of keratoconus / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To observe the epithelial remodeling of femtosecond laser-assisted stromal lenticule addition keratoplasty combined with corneal collagen cross-linking(SLAK-CXL)in patients with progressive keratoconus, investigate the remodeling rules of corneal epithelial and influencing factors, and provide clinical data for further refractive correction.METHODS: Retrospective and observational study. A total of 28 keratoconus patients(29 eyes)who received SLAK-CXL from September 2020 to October 2021 were included. Preoperative and postoperative visual acuity, intraocular pressure(IOP), diopter, keratometry and corneal epithelial thickness(CET)were recorded. The trend of CET change was observed. The factors affecting CET were analyzed according to the thickness and depth of the lenticule.RESULTS: Flattest meridian keratometry(Kf)and steepest meridian keratometry(Ks)at 1mo postoperatively were significantly larger than those preoperatively(P&#x003C;0.05). The thinnest corneal thickness(TCT)at 1, 2, 6mo and 1a postoperatively were significantly larger than preoperative(P&#x003C;0.05). The CET changed with time, with the central CET showing a larger variation tendency. The CET of superior, superior nasal, nasal, superior temporal in paracentral area were thinned, the CET of superior, temporal, superior temporal in midperipheral area were thinned, while the CET of superior nasal was thickened in peripheral area at 1, 2, 6mo and 1a postoperatively. The variation of CET was not correlated with the thickness or depth of lenticule at 1a postoperatively(P&#x003E;0.05).CONCLUSIONS: It is firstly found that the corneal morphology has changed after SLAK-CXL. CET decreases and then increases and then decreases again. At 1a postoperatively, the CET of the central and paracentral areas is thinner, while the CET of the midperipheral and peripheral areas is thicker. The degree of epithelial remodeling is not correlated with lenticule thickness or depth.

Characteristics of early changes in corneal epithelial thickness and related influencing factors after femtosecond assisted laser in situ keratomileusis / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the characteristics of changes in corneal epithelial thickness at the early postoperative stage of femtosecond assisted laser in situ keratomileusis(FS-LASIK)and its related influencing factors.METHOD: Retrospective study. A total of 120 patients(240 eyes)of myopia undergoing FS-LASIK from May 2021 to June 2022 were selected. The corneal epithelium thickness in the central area, inner ring area, and outer ring area of patients before and at 1d, 1wk, 1 and 3mo after operation was recorded. The relationship between the variation of corneal epithelium thickness and spherical equivalent, optical zone diameter, depth of cut and cutting ratio was analyzed by Pearson correlation.RESULTS: There was no statistical significance in corneal epithelial thickness in the central area, inner ring area and outer ring area at 1d after FS-LASIK compared with that before operation(P&#x003E;0.05). At 1wk, 1 and 3mo after surgery, the corneal epithelial thickness in the central area, inner ring area and outer ring area increased compared with that before surgery, and the corneal epithelial thickness in the central area and inner ring area at 1 and 3mo after surgery was greater than that in the outer ring area(all P&#x003C;0.05). The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thicker than that of low and moderate myopia patients before operation. The corneal epithelial thickness in the central, inner and outer ring areas of high myopia patients was thinner than that of low and moderate myopia patients at 1wk after operation(P&#x003C;0.05). At 1 and 3mo after operation, the corneal epithelial thickness in the central, inner and outer ring areas of patients with high myopia was greater than that of patients with low and moderate myopia, and the changes of corneal epithelial thickness in the central, inner and outer ring areas were greater than those of patients with low and moderate myopia(P&#x003C;0.05). The results of Pearson correlation showed that the changes in corneal epithelial thickness in the central and inner ring area were positively correlated with the corneal curvature, depth of cut and cutting ratio at 3mo after surgery, and they were in negative correlation with the age, spherical equivalent and optical zone diameter(P&#x003C;0.05).CONCLUSION: The corneal epithelial thickness of patients thickened after the FS-LASIK operation, and it was correlated with age, corneal curvature, preoperative depth of cut, cutting ratio, spherical equivalent and the optic zone diameter.