Changes In Corneal Thickness Research Articles

Early influence of endotamponade on corneal biomechanical parameters, central corneal thickness and accuracy of intraocular pressure measurement

To define the influence of air, SF6 gas and silicon oil 1000cs tamponade injection and oil tamponade removal on corneal biomechanics, central corneal thickness and intraocular pressure. 77 eyes referred to vitrectomy were divided into 4 groups: 19 to air tamponade, 21 to SF6 tamponade, 19 to oil tamponade, 18 to oil tamponade removal. Pre- and postoperative corneal hysteresis, corneal resistance factor, corneal thickness, Goldman intraocular pressure (GAT) and corneal compensated intraocular pressure (IOPcc) were analysed. GAT and IOPcc did not change after the air or SF6 tamponade. The oil tamponade injection caused increase in GAT and IOPcc, while the oil removal caused reduction in those parameters. In all groups, preoperative and postoperative values of GAT and IOPcc did not differ. There was no change in corneal thickness and biomechanics after air, SF6 or oil tamponade while after removal of oil those parameters are decreased. The air, SF6 and oil tamponade does not change the corneal thickness and corneal biomechanics. The removal of oil causes decrease in corneal thickness and biomechanics which can lead to bias in intraocular pressure measurement. GAT and IOPcc did not differ in eyes pre- and post-vitrectomy, being similarly reliable measure.

Comparison of Changes in Corneal Thickness and Curvature After Myopia Correction Between SMILE and FS-LASIK.

To comparatively investigate the changes in corneal thickness and curvature between small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). Data were collected preoperatively and postoperatively at 1 week, 1 month, and 3 months, including central corneal thickness (CCT), midperipheral corneal thickness (MPCT), peripheral corneal thickness (PCT), central keratometry (CK), midperipheral keratometry (MPK), and peripheral keratometry (PK), using a dual rotating Scheimpflug analyzer. At 1 week postoperatively, changes in CCT, MPCT, PCT, and PK were significantly greater in the SMILE group than in the FS-LASIK group (P = .003 for CCT and < .001 for MPCT, PCT, and PK), but no significant inter-group differences were found between changes in CK and MPK (P = .883 and .513, respectively). CCT, MPCT, and PK values showed a similar increase in both groups, but significantly more increase in PCT and significantly less increase in CK and MPK was observed in the SMILE group from 1 week to 3 months after surgery. At 3 months postoperatively, CCT and MPCT were significantly thinner in the SMILE group than in the FSLASIK group (P = .018 and .022, respectively), and there was no significant difference in PCT, CK, MPK, and PK between the two groups. SMILE caused significantly more corneal thinning at the center, midperiphery, and periphery, and more corneal flattening at the periphery, compared to FS-LASIK. A different pattern of corneal remodeling was observed between the two surgeries during the 3-month follow-up period. [J Refract Surg. 2023;39(1):15-22.].

Corneal Endothelial Morphology and Central Corneal Thickness Changes in Type 2 Diabetes Mellitus using Specular Microscopy and Ultrasonic Pachymetry: A Cross-sectional Comparative Study

Introduction: Diabetes Mellitus (DM) is a metabolic condition characterised by chronic hyperglycaemia, causing raised blood glucose levels which result in microvascular and macrovascular disorders and may introduce ocular manifestations including changes in corneal Endothelial Cell Density (ECD), corneal thickness, and intraocular pressure. It is clinically important to analyse the corneal endothelial status in patients with type II DM as preoperative corneal endothelial cell dysfunction may cause more corneal endothelial cell damage postoperatively leading to corneal decompensation. With the advent of precise and better measurement tool Central Corneal Thickness (CCT) and corneal endothelial morphology measurement has become more accurate. Aim: To compare corneal endothelium cell density, polymorphism, polymegathism and CCT in type 2 DM with age-matched, non diabetic control subjects using CEM-530 Specular microscope and ultrasonic pachymeter Tomey SP-100. Materials and Methods: This cross-sectional, comparative study was conducted at Eye Department at ESI Post Graduate Institute of Medical Sciences and Research, Basaidarapur, Delhi, India, from October 2018 to November 2019. Patients with ages between 40 to 70 years of either gender who were diagnosed to have DM were recruited in the study through non probability convenience sampling. A total of 150 subjects that met the inclusion criteria and exclusion criteria were included in the study. Seventy five known type 2 DM patients were enrolled in diabetic group (case group) and 75 non diabetic, age-matched subjects were enrolled as control group. Cases were classified under three major groups, namely on the basis of duration of DM and severity of Diabetic Retinopathy (DR) and glycaemic control {glycosylated haemoglobin (HbA1c) level}. All the findings were endorsed on a predesigned performa. Statistical Package for Social Sciences (SPSS) version 17.0 was used for analysis of data. Age and corneal parameters compared using unpaired t-test in diabetic and control group. Also, for comparison in between subgroup of diabetic patients on HbA1c level done by using Analysis of Variance (ANOVA) test. Chi-square test applied for categorical variables. Results: Among the 150 patients evaluated, type 2 DM patient’s corneas (540.51±32.578 µ) were thicker as compared to control group 517.51±22.155 µ (p-value&lt;0.001). The mean ECD of control and diabetic group patients was 2723.75±287.253 cells/mm2 and 2716.11±296.081 cells/mm2 , respectively, found insignificant (p-value=0.821). The mean Coefficient of Variation (CV) of cell area of control and diabetic patients was 28.87±3.950 and 29.85±4.027, respectively, and was significant (p-value=0.034). The mean percentage of endothelial Hexagonal cells (HEX%) of control and diabetic patients were 67.39±6.419 and 67.41±5.493, respectively and was non significant (p-value=0.985). Thus, statistically significant difference was found with CCT (p-value&lt;0.001) and CV (p-value=0.034) but not with ECD and hexagonality, between control and diabetic eyes. There was a correlation between CCT, CV, HEX% and ECD with duration of DM2 but it was statistically insignificant. There were higher CCT, CV and HEX% and lower ECD in &gt;10 years of duration of diabetes mellitus than in patients with duration of diabetes mellitus ≤10 years. There was a correlation of CCT, CV, ECD and HEX with HbA1c level. There were significant higher CCT and CV values in &gt;7% HbA1c level group than in group with ≤7% HbA1c level. There was also increased ECD in &gt;7% group, but it was found to be insignificant. Percentage of hexagonality in &gt;7% HbA1c level group was lower than in group with ≤7% HbA1c level, but found insignificant. There were higher values of CCT and CV in Non Proliferative Diabetic Retinopathy (NPDR) subgroup compared to Proliferative Diabetic Retinopathy (PDR) and no Diabetic Retinopathy group. CCT values were significant (p-value=0.007), so as CV values (p-value=0.001). There was increase in HEX% (p-value=0.005) which was significant, along with lower ECD in NPDR (p-value=0.143), group which was insignificant. Conclusion: The present study documented that DM has considerable effects on all the layers of the cornea especially endothelial layer, causes reduction of ECD and increased CV. Diabetic cornea has increased CCT and lower percentage of hexagonal cells than normal subjects. In addition, there is a correlation between the changes in corneal parameters like ECD, CV, HEX%, CCT with the duration of DM and severity of DR and glycaemic control {glycosylated haemoglobin (HbA1c) level}.

Corneal Endothelial Morphology and Central Corneal Thickness Changes in Type 2 Diabetes Mellitus using Specular Microscopy and Ultrasonic Pachymetry: A Cross-sectional Comparative Study

Introduction: Diabetes Mellitus (DM) is a metabolic condition characterised by chronic hyperglycaemia, causing raised blood glucose levels which result in microvascular and macrovascular disorders and may introduce ocular manifestations including changes in corneal Endothelial Cell Density (ECD), corneal thickness, and intraocular pressure. It is clinically important to analyse the corneal endothelial status in patients with type II DM as preoperative corneal endothelial cell dysfunction may cause more corneal endothelial cell damage postoperatively leading to corneal decompensation. With the advent of precise and better measurement tool Central Corneal Thickness (CCT) and corneal endothelial morphology measurement has become more accurate. Aim: To compare corneal endothelium cell density, polymorphism, polymegathism and CCT in type 2 DM with age-matched, non diabetic control subjects using CEM-530 Specular microscope and ultrasonic pachymeter Tomey SP-100. Materials and Methods: This cross-sectional, comparative study was conducted at Eye Department at ESI Post Graduate Institute of Medical Sciences and Research, Basaidarapur, Delhi, India, from October 2018 to November 2019. Patients with ages between 40 to 70 years of either gender who were diagnosed to have DM were recruited in the study through non probability convenience sampling. A total of 150 subjects that met the inclusion criteria and exclusion criteria were included in the study. Seventy five known type 2 DM patients were enrolled in diabetic group (case group) and 75 non diabetic, age-matched subjects were enrolled as control group. Cases were classified under three major groups, namely on the basis of duration of DM and severity of Diabetic Retinopathy (DR) and glycaemic control {glycosylated haemoglobin (HbA1c) level}. All the findings were endorsed on a predesigned performa. Statistical Package for Social Sciences (SPSS) version 17.0 was used for analysis of data. Age and corneal parameters compared using unpaired t-test in diabetic and control group. Also, for comparison in between subgroup of diabetic patients on HbA1c level done by using Analysis of Variance (ANOVA) test. Chi-square test applied for categorical variables. Results: Among the 150 patients evaluated, type 2 DM patient’s corneas (540.51±32.578 µ) were thicker as compared to control group 517.51±22.155 µ (p-value&lt;0.001). The mean ECD of control and diabetic group patients was 2723.75±287.253 cells/mm2 and 2716.11±296.081 cells/mm2 , respectively, found insignificant (p-value=0.821). The mean Coefficient of Variation (CV) of cell area of control and diabetic patients was 28.87±3.950 and 29.85±4.027, respectively, and was significant (p-value=0.034). The mean percentage of endothelial Hexagonal cells (HEX%) of control and diabetic patients were 67.39±6.419 and 67.41±5.493, respectively and was non significant (p-value=0.985). Thus, statistically significant difference was found with CCT (p-value&lt;0.001) and CV (p-value=0.034) but not with ECD and hexagonality, between control and diabetic eyes. There was a correlation between CCT, CV, HEX% and ECD with duration of DM2 but it was statistically insignificant. There were higher CCT, CV and HEX% and lower ECD in &gt;10 years of duration of diabetes mellitus than in patients with duration of diabetes mellitus ≤10 years. There was a correlation of CCT, CV, ECD and HEX with HbA1c level. There were significant higher CCT and CV values in &gt;7% HbA1c level group than in group with ≤7% HbA1c level. There was also increased ECD in &gt;7% group, but it was found to be insignificant. Percentage of hexagonality in &gt;7% HbA1c level group was lower than in group with ≤7% HbA1c level, but found insignificant. There were higher values of CCT and CV in Non Proliferative Diabetic Retinopathy (NPDR) subgroup compared to Proliferative Diabetic Retinopathy (PDR) and no Diabetic Retinopathy group. CCT values were significant (p-value=0.007), so as CV values (p-value=0.001). There was increase in HEX% (p-value=0.005) which was significant, along with lower ECD in NPDR (p-value=0.143), group which was insignificant. Conclusion: The present study documented that DM has considerable effects on all the layers of the cornea especially endothelial layer, causes reduction of ECD and increased CV. Diabetic cornea has increased CCT and lower percentage of hexagonal cells than normal subjects. In addition, there is a correlation between the changes in corneal parameters like ECD, CV, HEX%, CCT with the duration of DM and severity of DR and glycaemic control {glycosylated haemoglobin (HbA1c) level}.

Central Corneal Thickness and Endothelial Cell Changes after Phacoemulsification in Patients with Diabetes Mellitus: A Prospective Study

Central Corneal Thickness and Endothelial Cell Changes after Phacoemulsification in Patients with Diabetes Mellitus: A Prospective Study

Correlation between postoperative central corneal thickness and endothelial changes after cataract surgery by phacoemulsification in diabetic patients

Correlation between postoperative central corneal thickness and endothelial changes after cataract surgery by phacoemulsification in diabetic patients

Direct assessment of changes in biomechanical properties of the cornea after ReLEx SMILE and FemtoLASIK surgeries

The SMILE group comprised 23 patients (46 eyes) with spherical refraction -3.8±1.8 diopters (D), the FemtoLASIK group included 18 patients (36 eyes) with spherical refraction -3.5±1.3 D. Analysis of the biomechanical properties of the cornea was carried out using the CORVIS ST device (Oculus, Germany) before and seven days after corneal refractive surgery. In the SMILE group, with intraoperative decrease in corneal thickness of 91.43±19.43 µm, a significant increase in the following parameters was observed: deformation coefficient (DA ratio; p=0.0001), peak distance (PD; p=0.02) and inverse concave radius (ICR; p=0.003); a decrease in the stiffness parameter at first applanation (SP-A1; p=0.0001), Corvis biomechanical index (CBI; p=0.0001), intraocular pressure (IOP; p=0.001). In the FemtoLASIK group, with intraoperative decrease in corneal thickness of 75.33±32.3 µm, we observed a significant increase in DA ratio (p=0.0002), PD (p=0.04), ICR (p=0.0002), a decrease in SP-A1 (p<0.0001), IOP values (p=0.0003). In comparison with the FemtoLASIK group, the deformation amplitude DA changed significantly less in the SMILE group (p=0.04). In the FemtoLASIK group, in comparison with the SMILE group, the DA ratio (p=0.0009) and SP-A1 (p=0.0003) significantly increased. Intraoperative corneal thickness change correlates with ICR both in SMILE (R=0.52) and in FemtoLASIK (R=0.65). Corneal biomechanical properties determined with CORVIS ST in eyes with mild to moderate myopia change to a lesser extent after ReLEx SMILE compared to FemtoLASIK.

Role of corneal epithelial thickness during myopic regression in femtosecond laser-assisted in situ keratomileusis and transepithelial photorefractive keratectomy

The study aimed to investigate the relationship between changes in corneal epithelial thickness and the outcome of myopic regression after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial photorefractive keratectomy (TPRK). This study included 45 eyes of 25 patients undergoing FS-LASIK and 44 eyes of 24 patients undergoing TPRK. Myopic regression occurred in these patients postoperatively from 8 to 21 months. The corneal epithelial thickness was measured using a spectral-domain optical coherence tomography at the onset of regression, 3 months after treatment, and 3 months after drug withdrawal. Compared with that of preoperation, corneal epithelial thickness increased when regression occurred in both groups (all P < 0.05). The thickness of central corneal epithelium in FS-LASIK and TPRK groups reached 65.02 ± 4.12µm and 61.63 ± 2.91µm, respectively. The corneal epithelial thickness decreased when myopic regression subsided after 3 months of steroid treatment compared to the onset (P < 0.05). With a decrease in corneal epithelial thickness, the curvature of the anterior corneal surface, central corneal thickness, and refractive power all decreased (all P < 0.05). The corneal epithelial thickness and refractive error remained relatively stable after 3 months of treatment withdrawal (P > 0.05). The corneal epithelial thickness determined the outcome of myopic regression similarly in FS-LASIK and TPRK. When the corneal epithelium thickened, regression occurred. After steroid treatment, epithelial thickness decreased whereas regression subsided.

Corneal edema resorption after injury is regulated by the transcription factor NFAT5

AbstractIn cornea, injury or inflammation leads to an ingrowth of blood‐ and lymphatic vessels associated with corneal edema. That can lead to a loss of transparency which is the second most common cause for blindness worldwide. So far, the only treatment is corneal transplantation, resulting in more than a million people suffering from corneal blindness due to shortage of donor corneas. Recently we showed a positive role of lymphatic vessels in the resolution of corneal edema. The nuclear factor of activated T‐cells 5 (NFAT5/TonEBP) is an important transcription factor regulating lymphangiogenesis (LA) by modulating the expression of pro‐lymphangiogenic vascular endothelial growth factor C (VEGF‐C) in skin macrophages. It has not been investigated whether NFAT5 is expressed in the cornea and which role it plays in the inflammatory response after corneal injury.In this study, two NFAT5‐knockout mouse models were used: tamoxifen‐inducible systemic (UbcCre/NFAT5fl/fl) and a myeloid cell specific (LysMCre/NFAT5fl/fl). Both underwent perforating corneal injury (PCI) in the central cornea. Seven days after surgery, corneal edema and its resolution were measured using in vivo optical coherence tomography (OCT). The mean corneal thickness (MCT) was evaluated using MatLab®. Corneal inflammation was assayed via immunofluorescence. Bone marrow derived macrophages (BMDMs) from LysMCre/NFAT5fl/fl mice were stimulated with LPS/IFN‐γ for 24 h and used for pinocytosis assays using FITC‐conjugated dextran. Pinocytosis capacity was measured by calculating the ratio of FITC‐saturated cells to the total number of cells using MatLab®.In naive corneas, NFAT5 was mainly expressed in fibroblasts. After PCI, NFAT5 expression in fibroblasts was downregulated and mainly expressed by macrophages (Correlation coefficient of TonEBP+/Vimentin+: 0.446 ± 0.111 in naive corneas vs 0.153 ± 0.024 after PCI [p &lt; 0.0001]; TonEBP+/F480+: 0.113 ± 0.032 in naive cornea vs. 0.446 ± 0.018 after PCI [p &lt; 0.0001]). In uninjured corneas, NFAT5 knockout did not lead to changes in corneal thickness, however, the number of macrophages was significantly increased (24.76 ± 3.54% in knockout vs. 16.14 ± 0.36%; p = 0.0094 of corneal area covered by F480+ cells). After PCI, the resolution of corneal edema was enhanced in both, systemic NFAT5 knockout mice (Mean corneal thickness: 97.1 ± 10.0 μm in knockout vs. 137.1 ± 28.8 μm [p = 0.002]) and myeloid cell NFAT5 knockout mice (Mean corneal thickness: 97.1 ± 10.0 μm in knockout vs. 126.0 ± 16.6 μm; [p &lt; 0.001]). After incubation of BMDMs from LysMCre/NFAT5fl/fl mice with fluorescent dextran, the percentage of cells saturated which incorporated the fluorescent dextran in inflammatory stimulated macrophages was significantly higher in LysMCre+/NFAT5fl/fl macrophages compared to LysMCre−/NFAT5fl/fl macrophages (1.45 ± 0.28% vs. 0.61 ± 0.18%; [p &lt; 0.001]).Our results demonstrate that NFAT5 is highly expressed in the cornea and its expression shows considerable changes after PCI. Mechanistically, we found that myeloid cell‐derived NFAT5 is crucial for controlling corneal edema, as edema resorption after PCI was significantly enhanced in mice with conditional loss of NFAT5 in the myeloid cell lineage, presumably due to increased pinocytosis of corneal macrophages. Collectively, we uncover a suppressive role for NFAT5 in corneal edema resorption, thereby identifying a novel therapeutic target to combat edema‐induced corneal blindness.

Predictive models for IOPs measured with NCT, GAT, and ORA among patients undergoing SMILE.

Purpose: To develop predictive models for the intraocular pressure (IOP) of patients undergoing small incision lenticule extraction (SMILE) procedures, measured with a noncontact tonometer (NCT), Goldmann applanation tonometry (GAT), and an ocular response analyzer (ORA). Methods: In this prospective study, a total of 104 eyes (-6.23 ± 2.06 diopters) of 52 patients (24.38 ± 4.76years) undergoing SMILE procedures were included. The intraocular pressure was measured (IOPNCT with NCT, IOPGAT with GAT, and IOPcc and IOPg with ORA) before surgery and at postoperative 6months. Information on age, preoperative and attempted spherical equivalent (SE), ablation depth, preoperative values and postoperative changes in central corneal thickness (CCT), K1, K2, Km, corneal hysteresis (CH) and corneal resistance factor (CRF) values was collected in order to predict IOPs. Results: All surgeries were uneventful. At postoperative 6months, the efficacy and safety index were 1.04 ± 0.15 and 1.08 ± 0.18, respectively. Significant decreases were detected in postoperative IOPNCT, IOPGAT, IOPcc, and IOPg compared to preoperative values (all p < 0.001). No relationship was found between any IOP and ablation depth, attempted SE, and preoperative SE, as well as CCTdifference (all p > 0.05). Predictive models for IOPs were constructed to predict preoperative values, and R 2 values were 67.5% (IOPNCT), 64.5% (IOPGAT), 78.7% (IOPcc), and 82.0% (IOPg). The prediction band of IOPNCT and IOPGAT was 7.4-15.1mmHg and 8-16mmHg, respectively. Conclusion: Predictive models for IOP measurements after SMILE procedures can be helpful in clinical practice.

Corneal Aberrations and Thickness in Adults Born Small, Appropriate, or Large for Gestational Age at Term.

Background/Aims: This study investigated whether there are changes in corneal surface regularity and corneal thickness in adults born small, appropriate, or large for gestational age at term. Methods: This retrospective cohort study involved prospective Scheimpflug imaging of the cornea (Pentacam®) to compare the corneal thickness and aberrations between adults classified as small for gestational age (SGA), normal birth weight (BW), and large for gestational age (LGA). Multivariable linear regression was applied to analyze associations with gestational age, BW percentile, placental insufficiency, preeclampsia, and breastfeeding. Results: In total, 448 eyes of 261 individuals born full term (aged 29.9 ± 9.5 years, 140 females) were examined, including 29 severe SGA (BW < 3rd percentile), 32 moderate SGA (BW between 3rd and <10th percentile), 132 normal BW (BW between 10th and 90th percentile), 35 moderate LGA (BW between >90th and 97th percentile), and 33 severe LGA (BW > 97th percentile). There were no differences between groups in the corneal aberrations of the total cornea as well as of the corneal front surface, except for higher-order aberrations in the front of the cornea (p = 0.032). There was an association between the increased total root mean square of higher-order aberrations and lower birth weight percentile (p = 0.004), with increased higher-order aberrations correlating with lower visual acuity and spherical equivalent. Conclusion: Restricted prenatal growth is associated with increased higher-order aberrations in adulthood.

Corneal tissue changes following short-term soft contact lens wear of different materials.

To study the effect of different soft contact lens (CL) materials during short-term wear on corneal tissue. Twenty-two healthy participants wore both silicone hydrogel (MyDay, CooperVision) and hydrogel soft CLs (Biomedics 1day extra, CooperVision) for 8 h per lens. In each session, Scheimpflug images were captured before and immediately after CL removal. Images were analysed using the densitometry distribution analysis, a technique from which two parameters, α (corneal transparency) and β (corneal homogeneity), were estimated. In addition, the central corneal thickness changes after CL wear and the influence of the CL material on corneal transparency were evaluated. The β parameter (homogeneity) increased by 5% after wearing both CL materials (paired t-test, p< 0.001). However, the α parameter (transparency) only increased in half of the participants. No material was found to be more determinant in causing the corneal densitometry changes. Statistically significant but not clinically relevant changes in corneal thickness were observed. Biomarkers of corneal tissue integrity (α and β) were affected by short-term soft contact lens wear. The observed changes in corneal transparency and homogeneity were not clinically relevant but support the importance of participant-material biocompatibility.

Comparison of Visual Acuity, Refractive Status, Intraocular Pressure, Central Corneal Thickness, RNFL Thickness and Disc Changes Between Patients with Primary Open Angle Glaucoma and Primary Angle Closure Glaucoma - A Retrospective Observational Study

Aim and objective: To compare visual acuity, refractive status, intraocular pressure, central corneal thickness, RNFL thickness and disc changes between patients with primary open angle glaucoma and primary angle closure glaucoma Materials and methods: A retrospective study conducted over a period of 6 months with a sample size of 172 eyes from 100 patients. Various parameters including Pachymetry, IOP and gonioscopy were performed. Result: POAG is more in prevalence in the age group of 45- 60 and more in males than females. In general, POAG groups were predominantly myopic and have a thinner central corneal thickness average 534±24.6µm and leading to effects in Intraocular pressure. PACG is more prevalent among males than females in contrary to our reference and it is common in the age group 40-60yrs. PACG’s were more predominantly Hyperopic and having thicker CCT on an average of 544±25.7 µm. Conclusion: This study concludes that more rapid glaucomatous changes is seen in the patients with POAG than PACG. These patients should be screened carefully and provided more diagnostic and preventive management. Keywords: Primary open angle glaucoma, Primary angle closure glaucoma, Central corneal thickness, RNFL thickness.

Central Corneal Thickness Changes in Diabetic Retinopathy. A Prospective Observational and Correlative Study

Generally, there is a delay of 4 to 7 years in the diagnosis of type 2 diabetes and about 20% of patients would have already developed some micro vascular complications at the time of diagnosis. To study the central corneal thickness (CCT) variation and correlate with grades of diabetic retinopathy in an adult South Indian population. The study was conducted on 184 eyes each of T2DM patients of duration more than 5 years. 98 males (53.26%) &amp; 86 females (46.73%) were recruited. After recording age, sex and duration of diabetes, fundus examination was done. CCT measurements were determined using Ultrasonic Pachymetry. Diabetic retinopathy was classified based on ETDRS (Early diabetic retinopathy study) and mean CCT values of each group were correlated and statistically analysed using SPSS software Version 17. Out of 184 subjects recruited, 72 patients were with no diabetic retinopathy (NDR), 107 patients were with non-proliferative diabetic retinopathy (NPDR) and 5 patients were with proliferative diabetic retinopathy (PDR). The mean CCT of no diabetic retinopathy (NDR), non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) were found to be 526.14μm, 533.98μm and 555.20μm respectively. CCT was found to be thicker for diabetics with proliferative diabetic retinopathy compared to those with no retinopathy; the difference was not statistically significant (p=0.16). Uncontrolled diabetics (HbA1c &gt;7%) had thicker corneas compared with diabetics with good control which was statistically significant (p=0.003). CCT was higher in diabetics having duration &gt; 10 years than with duration &lt;10 years but was not statistically significant (p=0.117).

Detecting Subclinical Corneal Edema Using Corneal Thickness Mapping in Patients Presenting Fuchs Endothelial Corneal Dystrophy

To determine whether local corneal thickness changes observed with optical coherence tomography (OCT) can detect subclinical corneal edema in Fuchs endothelial corneal dystrophy (FECD). Retrospective cohort study. A series of patients presenting FECD who underwent cataract surgery alone (45 eyes) or with concomitant Descemet membrane endothelial keratoplasty (triple procedure; 117 eyes). The study reviewed medical records, collected the preoperative corneal thickness map and calculated the differences and ratio of corneal thickness measured at 5, 7, and 9 mm from the central corneal thickness. Area under the receiver operating characteristic curves (AUCs) were calculated and thresholds were selected to obtain a specificity of 90%. The median difference between 5- and 2-mm corneal thickness in the supra-nasal quadrant (∆5-2mmSN) was 38 µm (interquartile range 34-46) in the cataract group and 17 µm (2-38) in the triple procedure group (P < .001). The corneal thickness ratios of supra-nasal 5- to 2-mm (R5/2mmSN) and 7- to 2-mm (R7/2mmSN) were 1.07 (1.06-1.08) and 1.15 (1.13-1.17)] in the cataract group and 1.03 (1.00-1.06) and 1.09 (1.06-1.14) in the triple procedure group (P < .001). The probability of corneal edema was increased 7-fold with ∆5-2mm SN < 27 µm (AUC=0.76) and 9.4- and 7.4-fold with R5/2mmSN and R7/2mmSN < 1.045 (AUC=0.77) and 1.118 (AUC=0.76), respectively. Local changes in corneal thickness may be useful in detecting preclinical corneal edema, especially in patients with FECD undergoing cataract surgery.

Comparisons of the energy efficiency and intraocular safety of two torsional phacoemulsification tips

BackgroundDuring cataract phacoemulsification surgery, an Intrepid® balanced (IB) tip can achieve a larger amplitude, which may lead to higher energy efficiency than a Kelman (K) tip when paired with a torsional phaco platform. In this retrospective cohort study, we compared their energy efficiency and damage to the cornea under a new energy setting.MethodsThe medical records of 104 eyes of 79 patients were reviewed, with 47 eyes belonging to the IB group and 57 eyes belonging to the K group. All surgeries were performed on an Alcon Centurion® platform with gravity infiltration. Surgical parameters, visual outcome, central corneal thickness (CCT) changes, and endothelial cell density (ECD) loss rate were recorded and calculated.ResultsNo significant differences in postoperative best corrected visual acuity (BCVA), intraocular pressure (IOP), total ultrasound time, estimated fluid aspirated, CCT changes, or ECD loss rate were observed between the two groups. We divided the included eyes into soft nucleus and hard nucleus subgroups and found lower cumulative dissipated energy (CDE, 8.15 ± 8.02 vs 14.82 ± 14.16, P = 0.023), cumulative torsional energy (CTE, 8.06 ± 7.87 vs 14.13 ± 13.02, P = 0.027), and cumulative longitudinal energy (CLE, 0.09 ± 0.17 vs 0.69 ± 1.37, P = 0.017) in the IB group than in the K group, implying less energy used and higher energy efficiency of the IB tip.ConclusionLower CLE in the IB group indicates fewer phaco tip obstructions and a significantly higher capability to conquer hard nuclei with IB tips with statistical significance. With an ultra-perfusion cannula, the balanced tip does not cause more corneal damage.

Accelerated Corneal Collagen Cross-Linking Protocols for Progressive Keratoconus: Systematic Review and Meta-analysis.

The aim of this study was to compare the outcomes of 18 mW/cm 2 (5 minutes) versus 9 mW/cm 2 (10 minutes) accelerated corneal collagen cross-linking protocols in patients with progressive keratoconus. A systematic review and meta-analysis were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines, and electronic information was searched to identify studies comparing the outcomes of 5- versus 10-minute protocols in patients with progressive keratoconus. Mean changes in uncorrected visual acuity, best-corrected visual acuity, cylinder (diopters), thinnest corneal thickness, corneal keratometry values (K1 and K2), corneal high-order aberration (HOA), spherical aberration, coma, and trefoil were the primary outcome measures. Secondary outcome measures included the mean change in central corneal thickness and postoperative complications. Random effects modeling was used for the analysis. Four studies that enrolled 329 eyes were included. The 10-minute protocol had significantly improved outcomes compared with the 5-minute protocol for the mean changes in K1 and K2 ( P < 0.00001), corneal total HOA ( P = 0.0002), and corneal coma ( P = 0.00001). However, no statistically significant differences were found between the 2 protocols in uncorrected visual acuity, best-corrected visual acuity, cylinder, thinnest corneal thickness, spherical aberration, or trefoil. The 5-minute protocol was associated with a significantly lower mean change in the central corneal thickness for secondary outcomes. In addition, no significant differences were found between the 2 protocols for postoperative complications. The 10-minute protocol had better K1, K2, and HOA outcomes than the 5-minute protocol, but no statistically significant differences in the other outcomes.

Age-Related Changes in Corneal Epithelial Thickness Measured with an Ultrasound Pachymeter.

BackgroundThere is increasing research on the aging process of the cornea and its effect on the corneal parameters measured objectively. Nevertheless, the association of corneal epithelial thickness (CET) with age has yet to be fully illustrated.PurposeWe aimed to measure CET in healthy subjects to determine its age-related variation by using an ultrasound device.Patients and MethodsA total of one hundred and three subjects were enrolled in this study and grouped according to age: Group < 30 years, 31–40 years, 41–50 years, 51–60 years, 61–70 years, and > 71 years. The CET and total central corneal thickness (CCT) of each subject were measured by the Sonogage Corneo-Gage Plus 2 (Cleveland, Ohio) ultrasound pachymeter. The relationships between thickness values, laterality, age groups, and gender were analyzed using the Jonckheere-Terpstra test. The Partial correlation test was employed to assess the effect of age on the CET and CCT.ResultsThe mean CET was 47.88±1.15μm, with no statistically significant gender-related difference between right and left eyes. In addition, the CCT difference detected between female and male eyes was insignificant. The difference in mean CET across age groups was statistically significant (p =0.029). The difference in mean CET of left eyes across age groups was statistically significant (p=0.031). The mean CET and left CET of the oldest group were significantly thinner than the younger groups.ConclusionUltrasound pachymeter of the corneal epithelium demonstrated that there was no correlation between age and CCT, or gender. The CET becomes thinner with age in the central zone in both genders and there is no difference between males and females. Based on these results, age has a negative effect on CET. These findings could offer further insight into age-related changes in the cornea.

Corneal Epithelium Thickness and Refractive Changes After Myopic Laser Corneal Refractive Surgery

To evaluate the postoperative changes in corneal epithelium thickness and refractive power after femtosecond laser-assisted laser in situ keratomileusis (LASIK) and small incision lenticule extraction (SMILE) for myopia correction using anterior segment optical coherence tomography (OCT) with an integrated Placido disc topographer. The VisuMax 500-kHz femtosecond laser (Carl Zeiss Meditec AG) and Amaris 750 excimer laser (SCHWIND eye-tech-solutions) were used. Central, paracentral, and 6-mm epithelial thickness values were obtained, and the change in the value of epithelial thickness was calculated. Changes in the refractive power of the epithelium were also evaluated. The repeatability of this new measurement was also analyzed using the intraclass correlation (ICC). The total follow-up period was 6 months. A total of 77 LASIK eyes were matched with 77 SMILE eyes. Mean spherical equivalent was -3.92 ± 1.67 diopters (D) for LASIK versus -4.02 ± 1.63 D for SMILE (P = .356). Epithelial thickness parameters significantly and equally thickened in both types of surgery. The change in the value of epithelial thickness was positively correlated with spherical aberration. Analysis of the refractive power of the corneal epithelial layer (ICC > 0.70) showed a tendency for the postoperative myopization of the refractive component of this layer (-0.11 D for SMILE and -0.53 D for LASIK at 3 mm) and an increase in its cylinder and aberrometry. Increasing postoperative spherical aberration and epithelial thickness increased myopization of the epithelial refractive sphere (P < .05). Corneal epithelium thickens similarly after LASIK and SMILE, being slightly higher after SMILE. This correlates with the induced spherical aberration. Corneal epithelium thickening induces myopization of its refractive power, which accounts for a slight regression of the net refractive power change on the treated cornea. [J Refract Surg. 2022;38(9):602-608.].

Corneal epithelial remodeling after femtosecond laser-assisted in situ keratomileusis combined with intraoperative accelerated corneal collagen crosslinking for myopia: a retrospective study

BackgroundThis study analyzed regional corneal thickness remodeling, biomechanical properties, and visual outcomes after femtosecond laser-assisted in situ keratomileusis combined with intraoperative accelerated corneal collagen crosslinking (LASIK Xtra) for myopia.MethodsThis retrospective study analyzed 21 consecutive patients (18 women, three men; 42 eyes) who were treated with LASIK Xtra. All treatments were performed with ultraviolet-A (energy, 2.7 J/cm2; irradiance, 30 mW/cm2), using continuous (90 s) illumination. Postoperative values of corneal biometrics and visual outcomes were compared with preoperative values. Corneal thickness changes were evaluated using anterior segment optical coherence tomography. All patients were followed up for 12-month postoperatively. Preoperative and postoperative data were compared statistically using the paired t-test for normally distributed parameters and the Wilcoxon rank-sum test and Friedman analysis of variance with Bonferroni correction for non-normally distributed data.ResultsUncorrected distance visual acuity (UDVA) significantly improved at 6-month after surgery (P < 0.001). The central and inner regional corneal epithelial thickness significantly increased after LASIK Xtra (P < 0.05 for all), while the peripheral corneal epithelial thickness remained stable at 12-month after surgery. There was also a statistically significant decreased in the stromal thickness at most locations (P < 0.05 for all), except in the outer superior and outer superior-temporal regions.ConclusionsLASIK Xtra provided improvement in UDVA, corneal curvature, and corneal biomechanical stability. Because the results of this retrospective study results depended on the cohort members’ past information, it was inferred and confirmed that regular corneal thickness remodeling occurred after treatment.