Thickness Of Cornea Research Articles

Central Corneal Thickness: Comparison between diabetics and nondiabetics

Background and objectives: The cornea play a significant role in eye refraction. With early detection and prompt treatment, ocular problems linked to diabetes mellitus can be prevented from progressing. The purpose of this study was to compare the central corneal thicknesses of diabetic and non-diabetic patients. Methods: In Duhok Teaching Eye Hospital; a comparative cross-sectional study had been conducted between 01.01.2022 and 30.06.2022. There were 100 participants, 50 in diabetes group, and 50 in a control group. The diabetic group is further subdivided into three categories based on the duration of diabetes (less than 5 years, more than 5 to10 years, and above 10 years), as well as two subgroups based on the type of diabetes mellitus (type I and type II). The thickness of the central cornea was measured using SIRIUS corneal pachymetry and topography. Results: There was no statistically significant difference between the non-diabetic and diabetic groups in terms of central corneal thickness (549.6 micrometers 541.4 micrometers, P > 0.05). There was a statistically significant difference (P 0.05) between the mean central corneal thickness of diabetics with diabetes mellitus for more than ten years and non-diabetics and diabetics with diabetes for five years. Conclusion: In comparison to both non-diabetics and diabetics with diabetes for five years or less, those with long-term diabetes mellitus (diabetes for more than ten years) had a bigger statistically significant average central corneal thickness.

Relationship between hyperglycemia and intraocular pressure, corneal biomechanics, and corneal topography during the oral glucose tolerance test in nondiabetic patients.

Altered corneal biomechanics in patients with diabetes may affect intraocular pressure (IOP) measurements. Although a relationship between IOP and glucose levels has been reported in diabetic and nondiabetic patients, the mechanism by which hyperglycemia influences IOP is unclear. The aim of this study was to determine the effects of hyperglycemia on IOP, corneal biomechanics, and anterior segment parameters during the oral glucose tolerance test (OGTT) in nondiabetic patients. Twenty-one patients without DM who underwent OGTT were included in this study. A complete ophthalmologic examination was performed before the test. Blood glucose, insulin level, IOP (iCare rebound tonometer), Ocular Response Analyzer, and corneal topography (Pentacam) measurements were obtained at 0, 1, and 2h during the OGTT. Data from the patients' right eyes were included in the analysis. The mean age of the patients was 46.9 ± 11.0years. There was a statistically significant difference in IOP between 1 and 2h (p = 0.03) and a clinically significant difference between 0 and 1h (p = 0.06). Corneal resistance factor was lower at 2h than 1h (p = 0.03), while central cornea thickness was increased at 1h (p = 0.01) and 2h (p = 0.05) compared to 0h. There was positive partial correlation between hyperglycemia and IOP at 1h (p = 0.049, r = 0.67). The positive partial correlation between IOP and glucose level suggests that acute hyperglycemia may lead to increased IOP. However, further research is needed to explain the mechanism of IOP elevation in the hyperglycemic phase during OGTT.

Posterior corneal surface stability after femtosecond laser-assisted in situ keratomileusis in patients with myopia and myopic astigmatism.

To evaluate the variation and stability of the posterior cornea surface parameters (posterior cornea curvature [PCC], posterior cornea astigmatism [PCA], and posterior cornea elevation [PCE]) after femtosecond laser-assisted in situ keratomileusis (LASIK) in patients with myopia and myopic astigmatism over a period of 6 months or longer. This retrospective study comprised 284 right eyes. Patients aged 18 years or older with myopia up to -12.00 D and/or astigmatism up to -6.00 DC and who underwent femtosecond LASIK were recruited. Patients were divided into three subgroups: low myopia (-0.50 to -3.00 D), moderate myopia (>-3.00 to ≤-6.00 D), and high myopia (>-6.00 D), according to their pre-LASIK spherical equivalent (SE). The variables included for analysis were PCC (central 0-3.0 mm, pericentral 3.0-6.0 mm, and peripheral region 6.0-9.0 mm), PCE, PCA, internal anterior chamber depth, intraocular pressure, and central cornea thickness at the pre- and post-LASIK stages. The central PCC remained unchanged across all three myopia subgroups at 1 month when compared to the pre-LASIK stage and remained stable at 6 months. The pericentral regions became flatter across all myopia subgroups at 1 month postsurgery (P < 0.001) and remained unchanged at 6 months. This trend was not seen in the peripheral cornea regions, which remained unchanged at 1 and 6 months post-LASIK when compared to pre-LASIK mean readings. There were minimal changes in post-LASIK posterior cornea astigmatism throughout follow-up. There was no incidence of post-LASIK surgery ectasia in this study population. Post-LASIK, the different cornea subregions behaved differently. Overall, the posterior cornea surface remained stable post-LASIK across all myopia subgroups throughout follow-up.

The Utilization of Brillouin Microscopy in Corneal Diagnostics: A Systematic Review.

Corneal biomechanical data has been used since 2005 to screen for keratoconus and corneal ectasia by corneal specialists. Older technology uses force applanation techniques over a 3 mm area in the central cornea, making it highly dependent on extraneous variables and unable to calculate the elasticity of the tissue. Brillouin microscopy is a newer method that uses a natural shift in the frequency of light as it passes through a material. This frequency shift can be used to estimate the viscoelasticity of the tissue. The advantage of Brillouin microscopy is that it can create a full three-dimensional (3D) map of the entire cornea without direct contact. A literature search was conducted using the databases PubMed, Google Scholar, and Ovid regarding the applications of Brillouin microscopy in corneal diagnostics. A final total of 16 articles was included describing the various ex vivo and in vivo studies conducted using Brillouin microscopy. Applications of this technology spanned from keratoconus diagnosis to post-corneal refractive surgery evaluation. All studies evaluated corneal biomechanics and other corneal properties through the quantification of Brillouin frequency shifts. Many of the studies found that this diagnostic device is capable of detecting subtle changes in corneal thickness and biomechanics in keratoconic corneas at a high level of specificity and sensitivity. However, limitations of Brillouin microscopy may include the duration of time required for use and fluctuations in accuracy depending on the corneal hydration state. Future technology seems to be geared towarda combination of optical coherence tomography (OCT) and Brillouin microscopy, using OCT as a three-dimensional pupil-tracking modality. Further research and understanding of the technology involved will lead to better care of patients in the field of ophthalmology.

The Influence of Corneal Thickness on Surgically Induced Corneal Astigmatism Derived from Total Keratometry Measured by Anterior Segment Swept-Source OCT.

The purposeof the study was to explore the possible correlations between the anterior segment parameters derived from anterior segment swept-source optical coherence tomography (AS-SS-OCT) with the surgically induced corneal astigmatism (CSIA) calculated from total keratometry (TK) measured by AS-SS-OCT. Seventy-one eyes of 67 patients with age-related cataract who underwent phacoemulsification combined with intraocular lens implantation with 2.2-mm incision were included. The CSIA values were calculated from anterior keratometry (CSIAKant) and TK (CSIATK) measured by AS-SS-OCT, respectively. Hotelling's T2 test was used to evaluate the difference. The correlation of CSIA with various parameters derived from AS-SS-OCT was tested with the Spearman correlation coefficient. The centroid of CSIAKant and of CSIATK were 0.31 ± 0.55 D @ 54° and 0.41 ± 0.59 D @ 51°, with no significant difference (F = 1.283, p = 0.281, Hotelling's T2). The mean absolute CSIAKant and CSIATK were 0.58 ± 0.24 D and 0.65 ± 0.28 D. Spearman test showed that the magnitude of CSIAKant was negatively correlated with preoperative peripheral corneal thickness (PCT, p = 0.045) and the magnitude of anterior keratometry (p = 0.044). The magnitude of CSIATK was negatively correlated with preoperative central corneal thickness (CCT, p = 0.003) and preoperative PCT (p = 0.015). The increased thickness of the peripheral cornea is correlated with the decrease in the magnitude of the CSIA. The correlation we identified between the corneal thickness and the CSIA indicated that certain preoperative parameters should be considered for the prediction of CSIA for a more precise refractive outcome.

Insights into atypical segmental layer thicknesses and phase retardation in thick corneas using ultrahigh-resolution polarization-sensitive optical coherence tomography

BackgroundAccurately assessing corneal structural status is challenging when thickness deviates from the average. Polarization-sensitive optical coherence tomography (PS-OCT) measures tissue-specific polarization changes, providing additional contrast for accurate segmentations and aids in phase retardation (PR) measurements. Previous studies have shown PR's effectiveness in identifying sub-clinical keratoconus (KC) in asymmetric cases. Thus, this study aims to assess PR distribution in thick corneas with and without KC.MethodsIn this retrospective and cross-sectional study, 45 thick corneas from 30 Asian-Indian subjects, categorized into healthy (n = 26) and KC (n = 19) groups were analyzed. All eyes underwent standard clinical evaluations, tomographic assessments, and corneal biomechanics measurements. PR and individual layer thicknesses were measured using custom-designed ultrahigh-resolution PS-OCT. PR en-face maps were generated. Individual layer thicknesses and PR analysis was conducted across multiple zones, extending up to 8–10 mm in diameter. All eyes in the study had not undergone interventions, received topical medications, or had previous corneal disease history.ResultsSignificant differences were found in spherical and cylindrical powers, keratometry, pachymetry, and biomechanical indices (all P < 0.01). Thickness profiles from PS-OCT showed significant differences in the 4–8 mm zones only. Bowman's layer thickness significantly differed only in the central 2 mm zone (P = 0.02). The median PR values showed marginal differences in the central 2 mm zone (P = 0.0565). Additionally, there were significant differences observed in the 2–4 mm and 4–6 mm zones (P = 0.0274 and P = 0.0456, respectively). KC eyes exhibited an atypical PR distribution and corneal thinning, while normal eyes maintained a uniform Bowman’s layer thickness and PR maps with larger areas of higher PR.ConclusionThe study revealed distinctive PR distribution in thick corneas among healthy and KC groups. Using an ultrahigh-resolution PS-OCT the significance of Bowman's layer thickness in these groups was also emphasized. The study offered potential improvements in clinical diagnostics by enhancing our understanding of corneal structure and its altered function.

Comparison of intraocular pressure measurements with the tono-pen, goldmann applanation tonometer, and noncontact tonometer in nonglaucomatous pseudophakic children.

To evaluate the agreement between the Goldman applanation tonometer (GAT), Tono-Pen, and noncontact tonometer (NCT) in the measurement of intraocular pressure (IOP) in pseudophakic children. The medical records of nonglaucomatous pseudophakic children between 2009 and 2019 were retrospectively analyzed. A total of 46 eyes of 23 patients operated for bilateral pediatric cataract were included in the study. The patients' mean age was 13.4 ± 4.1years. Central corneal thickness (CCT) and IOP values measured with the GAT, Tono-Pen, and NCT were recorded. Agreement between the tonometers was evaluated by intraclass correlation coefficients (ICC) and the Bland-Altman method. The mean IOP of the 46 eyes included in the study was measured as 13.7 ± 2.3mm Hg with the GAT, 16.0 ± 2.3mm Hg with NCT, and 16.5 ± 2.3mm Hg with the Tono-Pen (p < 0.001). There is no statistical difference between NCT and Tono-Pen measurements, while GAT measurements were significantly lower than those of the NCT and Tono-pen. ICC values showed fair agreement between NCT and Tono-Pen (ICC = 0.720), whereas there was poor agreement between GAT and NCT (ICC = 0.501) and Tono-pen (ICC = 0.314). With all devices included in the study, thicker corneas were associated with higher IOP measurements. Although there was moderate agreement between the NCT and Tono-Pen, there was a statistically significant difference in the IOP values provided by the three devices. Our results suggest these devices should not be used interchangeably.

Comparative Analysis of Endothelial Cell Density and Central Thickness of Corneas Used for Endothelial Keratoplasty Procedures Using Various Storage Solutions.

The goal of this study was to evaluate the effect of various Food and Drug Administration-approved storage solutions on endothelial cell density (ECD) and central corneal thickness (CCT). We analyzed 6220 tissues used for endothelial keratoplasty procedures between January 2022 and June 2023 that were stored in either Life4°C, Optisol-GS, Kerasave, or Eusol-C under hypothermic conditions. We analyzed preprocessing CCT, success rate of meeting surgeon's Descemet stripping automated endothelial keratoplasty (DSAEK) thickness preferences, and preprocessing and postprocessing ECD. Results were analyzed using one-way analysis of variance, followed by multiple pairwise comparisons using the Tukey test. Mean preprocessing CCT was significantly lower in the Life4°C group (532 μm) than in Optisol-GS (549 μm), Kerasave (582 μm), and Eusol-C (589 μm) groups (all P < 0.0001). Preprocessing CCT in the Optisol-GS group was significantly lower than in Kerasave and Eusol-C groups (F (3, 3273) = 153.1, all P < 0.0001). Success rate of meeting surgeon DSAEK preferences was statistically similar among all 4 groups. Preprocessing ECD of the Kerasave group (2821 cells/mm2) was numerically higher than of the Eusol-C (2791 cells/mm2), Life4°C (2759 cells/mm2), and Optisol-GS (2768 cells/mm2) groups (P = 0.3232, 0.0004, and 0.0015, respectively). Corneal tissues stored in Kerasave and Eusol-C are significantly thicker than those in Life4°C and Optisol-GS. However, the success rate of meeting surgeon DSAEK preferences is similar among all 4 storage solutions.

Recurrence Characteristics on Optical Coherence Tomography and Treatments of Reis-Bücklers Corneal Dystrophy After Phototherapeutic Keratectomy or Penetrating Keratoplasty

PurposeTo evaluate the recurrence characteristics on optical coherence tomography and clinical outcomes after phototherapeutic keratectomy (PTK) or penetrating keratoplasty (PKP) in patients with Reis-Bücklers corneal dystrophy (RBCD). DesignRetrospective interventional case series. MethodsSeventeen patients with RBCD (31 eyes, including six surgery-naïve eyes and 25 surgical eyes) received 44 surgical interventions from 1996 through 2022. PTK or PKP was performed as the initial surgical procedure. Significant recurrence was determined when best spectacle-corrected visual acuity decreased at least two lines with increased opacity in the superficial cornea. Repeated PTK or PTK on the corneal graft (CG-PTK) was considered if patients could not endure poor vision due to significant recurrence. Recurrence depth and annual increase in thickness of the central cornea and subepithelial deposits were assessed by anterior segment optical coherence tomography. ResultsThe mean follow-up time was 12.8±8.5 years (range, 2.0–25.5 years). The mean logMAR best spectacle-corrected visual acuity improved from 1.24±0.48 preoperatively to 0.27±0.09 postoperatively in the initial PTK group (13 eyes, P<0.001), from 1.84±0.69 to 0.40±0.13 in the PKP group (12 eyes, P<0.001), from 1.04±0.46 to 0.30±0.07 in the repeated PTK group (12 times in 7 eyes, P<0.001), and from 1.29±0.43 to 0.39±0.11 in the CG-PTK group (7 times in 5 eyes, P=0.001). The median significant recurrence time was 27 months (95% confidence interval 23.9-30.1), 96 months (84.1-107.9), 31 months (28.8-33.1), and 24 months (19.8-28.2), respectively (P<0.001). The depth of superficial deposits located between the epithelium and the anterior stroma was approximately 115μm (85-159μm). The annual thickening of subepithelial deposits was 14±2μm after initial PTK, 7±3μm after PKP, 14±3μm after repeated PTK, and 30±11μm after CG-PTK, compared to 4±2μm in surgery-naïve eyes (P=0.002, 0.515, 0.002, <0.001). The thickness of the central cornea increased by 15±2μm, 7±2μm, 15±3μm, and 31±10μm per year in the four surgery groups, respectively, compared to 5±2μm in surgery-naïve eyes (P=0.001, 0.469, 0.001, <0.001). ConclusionsBetter visual acuity can be achieved after PTK than PKP for treatment of RBCD. The annual thickening of subepithelial deposits may approximate an increase in central corneal thickness. The superficial distribution of subepithelial deposits makes it feasible to perform repeated PTK, even on the corneal allograft, for recurrent RBCD.

Distribution of Intraocular Pressure in Indigenous Black Africans and Related Risk Factors: A Population-Based Study in Southwest Nigeria

Background: Elevated intraocular pressure (IOP) is a major risk factor for glaucoma and is presently the only modifiable risk factor. Even in a healthy population, IOP distribution varies among different racial groups. Objective: To determine the distribution of IOP and factors affecting it, among an indigenous African population in Southwest Nigeria. Methods: A population-based descriptive cross-sectional survey with an analytical component was performed. The study was conducted among participants 16 years and older who were residents of Akinyele Local Government Area of Oyo State and were all black Africans. A multi-stage sampling with probability proportional to size was used to identify the study population. All participants were examined at the local health center in their community, assessing the visual acuity, Goldmann applanation tonometry, central corneal thickness, anterior segment, fundoscopy, weight, height, and blood pressure. Results: A total of 1810 respondents completed the study; male patients accounted for 41.55%. Mean age was 49.43 ± 15.57 years. The mean IOP was 15.91 ± 4.74 mmHg. There was a significant association between elevated IOP and the male gender. Intraocular pressure also had a significant positive correlation with increasing age, systolic blood pressure, and central cornea thickness. There was no significant relationship between IOP and self-reported diabetes mellitus. Conclusion: The mean IOP and distribution in this study were a bit different from that observed in studies in different geographical locations but similar to studies in West Africa. It may be advisable to employ a geographical approach to normal IOP interpretation.

Diagnosis of Forme Fruste Keratoconus Using Corvis ST Sequences with Digital Image Correlation and Machine Learning.

This study aimed to employ the incremental digital image correlation (DIC) method to obtain displacement and strain field data of the cornea from Corvis ST (CVS) sequences and access the performance of embedding these biomechanical data with machine learning models to distinguish forme fruste keratoconus (FFKC) from normal corneas. 100 subjects were categorized into normal (N = 50) and FFKC (N = 50) groups. Image sequences depicting the horizontal cross-section of the human cornea under air puff were captured using the Corvis ST tonometer. The high-speed evolution of full-field corneal displacement, strain, velocity, and strain rate was reconstructed utilizing the incremental DIC approach. Maximum (max-) and average (ave-) values of full-field displacement V, shear strain γxy, velocity VR, and shear strain rate γxyR were determined over time, generating eight evolution curves denoting max-V, max-γxy, max-VR, max-γxyR, ave-V, ave-γxy, ave-VR, and ave-γxyR, respectively. These evolution data were inputted into two machine learning (ML) models, specifically Naïve Bayes (NB) and Random Forest (RF) models, which were subsequently employed to construct a voting classifier. The performance of the models in diagnosing FFKC from normal corneas was compared to existing CVS parameters. The Normal group and the FFKC group each included 50 eyes. The FFKC group did not differ from healthy controls for age (p = 0.26) and gender (p = 0.36) at baseline, but they had significantly lower bIOP (p < 0.001) and thinner central cornea thickness (CCT) (p < 0.001). The results demonstrated that the proposed voting ensemble model yielded the highest performance with an AUC of 1.00, followed by the RF model with an AUC of 0.99. Radius and A2 Time emerged as the best-performing CVS parameters with AUC values of 0.948 and 0.938, respectively. Nonetheless, no existing Corvis ST parameters outperformed the ML models. A progressive enhancement in performance of the ML models was observed with incremental time points during the corneal deformation. This study represents the first instance where displacement and strain data following incremental DIC analysis of Corvis ST images were integrated with machine learning models to effectively differentiate FFKC corneas from normal ones, achieving superior accuracy compared to existing CVS parameters. Considering biomechanical responses of the inner cornea and their temporal pattern changes may significantly improve the early detection of keratoconus.

Central versus peripheral thickness in the human cornea explained

PurposeThe human cornea is thicker in the periphery than the center and it has been suggested that this must be due to greater numbers of lamellae in the peripheral corneal stroma. The purpose of this study was to use high-resolution ultrastructural imaging to determine if the greater thickness of the peripheral cornea is due to the presence of more lamellae or if there is some other anatomical explanation. MethodsIn this study, full thickness corneas from three human donors were processed for light microscopy (LM) and transmission electron microscopy (TEM). Images were taken in three distinct stromal regions (anterior, middle, and posterior) from the central and peripheral cornea. Stromal thickness was evaluated by LM while TEM was used to evaluate numbers and thicknesses of lamellae, mean collagen fibril diameter, and mean collagen fibril density. ResultsMean stromal thickness was significantly thinner in the central (415 ± 34 µm) compared to the peripheral (536 ± 29 µm) cornea (P = 0.009). Numbers of lamellae were not significantly different between central (246 ± 14) and peripheral (251 ± 14) cornea. Average lamellar thickness was not different across all regions of the cornea, except for the peripheral posterior where the lamellae were approximately 50 % thicker (P < 0.05). Collagen fibril diameters were larger in the peripheral cornea by approximately 30 % when compared to the central cornea, in all regions (P < 0.01). ConclusionsThis study shows that it is an increase peripheral posterior lamellar thickness, rather than an increase in the number of lamellae, that accounts for the increase in corneal stromal thickness in the periphery of the human cornea. While collagen fibril diameters are greater throughout the peripheral stroma, the lamellae in the mid and anterior peripheral stroma are not thicker than centrally.

Correlation between HbA1C and CCT in T2DM

Abstract An observational cohort study of central corneal thickness (CCT) in type 2 diabetes mellitus (T2DM) patients in hyperglycemic and euglycemic states. Context: To assess the significance of glycemic control in CCT measurement. Aims: The main aim was to assess the change in CCT with the change in glycemic state by following them after 3 months. Settings and Design: This study was carried out in the department of ophthalmology, SMVMCH, Pondicherry. Materials and Methods: This is an observational cohort study carried out at Sri Manakula Vinayagar Medical College and Hospital after obtaining ethics committee clearance. Fifty-six T2DM patients with HbA1C &gt;7 were included in this study with informed consent. Clinical history with complete ophthalmic examination done, CCT was measured using ultrasonic pachymetry (UP) along with blood samples to measure their blood sugars and HbA1C values. They were advised to follow up on the treatment given by the medical department. Patients were reviewed after 3 months to measure the CCT and blood sugar values. Statistical Analysis: Done using STATA software 16.0. Continuous data and categorical data were assessed using paired t-test and Chi-square test, respectively. Normality of data using Shapiro–Wilk normality test. Statistical significance was adopted with P &lt; 0.05. Results: In our study, the initial mean HbA1C was 9.4 ± 1.9 and mean CCT was 552.6 ± 40.6 μm, whereas follow-up mean HbA1C was 7.1 ± 1.2 and mean CCT was 548.5 ± 38 μm which shows statistical significance. Conclusion: Diabetics present with thicker corneas and there is a decrease in thickness once glycemic control has been achieved. Keeping this in mind, we suggest assessment of CCT in all diabetic patients during clinical work-up.

Use of discarded corneo-scleral rims to create cornea-like tissue.

Corneal disease is a major cause of blindness. Transplantation of cadaver-derived corneas (keratoplasty) is still the current therapy of choice; however, the global shortage of donor corneas continues to drive a search for alternatives. To this end, biosynthetic corneal substitutes have recently begun to gain importance. Here, we present a novel method for the generation of a cornea-like tissue (CLT), using corneo-scleral rims discarded after keratoplasty. Type I collagen was polymerized within the corneo-scleral rim, which functioned as a 'host' mould, directing the 'guest' collagen to polymerize into disc-shaped cornea-like material (CLM), displaying the shape, curvature, thickness, and transparency of normal cornea. This polymerization of collagen appears to derive from some morphogenetic influence exerted by the corneo-scleral rim. Once the CLM had formed naturally, we used collagen crosslinking to fortify it, and then introduced cells to generate a stratified epithelial layer to create cornea-like tissue (CLT) displaying characteristics of native cornea. Through the excision and reuse of rims, each rim turned out to be useful for the generation of multiple cornea-shaped CLTs. The approach effectively helps to shorten the gap between demand and supply of CLMs/CLTs for transplantation. We are exploring the surgical transplantation of this CLT into animal eyes, as keratoprostheses, as a precursor to future applications involving human eyes. It is possible to use either the CLM or CLT, for patients with varying corneal blinding diseases.

Association between body stature with ocular biometrics and refraction among Chinese preschoolers

PurposeTo evaluate the association of body stature with ocular biometrics and refraction in preschool children.MethodsA cross-sectional, school-based study was conducted in Shenzhen, China. Preschool children aged 3 to 6 from 10 randomly-selected kindergartens were recruited. Ocular biometric parameters, including axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD), corneal radius curvature (CR), axial length to corneal radius ratio (AL-to-CR ratio) and lens thickness (LT) were measured using non-contact partial-coherence laser interferometry. Cycloplegic refractions were obtained by a desktop autorefractor. Body height and weight were measured using standard procedures. The association between body stature and ocular biometrics were analyzed with univariable and multivariable regression model.ResultsA total of 373 preschoolers were included. AL, ACD, VCD, CR, and AL-to-CR ratio, were positively associated with height and weight (p < 0.05), whereas LT was negatively associated with height and weight (p < 0.01). No association was observed between stature and central cornea thickness and refraction. After adjusted for age and gender in a multivariable regression model, AL had positive associations with height (p < 0.01) and weight (p < 0.01). However, refraction had no significant association with stature parameters.ConclusionTaller and heavier preschoolers had eyes with longer AL, deeper vitreous chamber, and flatter cornea. The significant associations between body stature and ocular biometric parameters reveal the driving influence of body development on the growth of eyeballs in preschoolers.

Comparison of keratometric values and anterior segment parameters measured using Scheimpflug Sirius topography and Lenstar biometry.

This study aimed to evaluate the consistency of preoperative keratometric values, anterior segment, and intraocular lens (IOL) power measurements in patients with cataract and no comorbidities using the Sirius topography device (CSO, Italy) and Lenstar LS 900 (Haag-Streit AG, Köeniz, Switzerland). Patients with grade 2 and 3 cataracts who applied to Ophthalmology Clinic of Dışkapı Yıldırım Beyazıt Education and Research Hospital, University of Health Sciences and planned for cataract surgery were included the study. Forty eyes with cataract from 40 patients were taken in the study. All patients underwent preoperative assessment using a combined Scheimpflug-Placido disc-based tomography device (Sirius) and Lenstar before cataract surgery. Keratometric measurements, such as flat keratometry (K1), steep keratometry (K2), and maximum keratometry (Kmax), and anterior segment parameters, white-to-white (WTW) distance, IOL power, astigmatism (AST), anterior chamber depth (ACD), aqueous depth (AD), and central cornea thickness (CCT), were recorded. There were significant differences between K1Lenstar and K1Sirius, K2Lenstar and K2Sirius, KmaxLenstar and KmaxSirius, WTWLenstar and WTWSirius, and IOL powerLenstar versus IOL powerSirius. However, there were insignificant differences between ASTLenstar and ASTSirius, ACDLenstar versus ACDSirius, ADLenstar and ADSirius, and CCTLenstar and CCTSirius variables. Furthermore, it was found that Sirius measured significantly higher than Lenstar, especially in terms of IOL power. Significant differences were observed between Lenstar and Sirius in terms of keratometric values, WTW distance, and IOL power. The IOL power value measured with Sirius was found to be higher than the IOL power value measured with Lenstar.

A comparative study of central corneal thickness in patients with diabetes and without diabetes mellitus

Diabetes mellitus (DM) is becoming increasingly and seriously prevalent lifestyle health problem worldwide. Up to 70% of diabetic patients can develop corneal changes and are also difficult to manage. Several studies were done to find out the morphological changes in cornea in type 2 DM, but the results are highly variable. Central corneal thickness (CCT) is widely considered as a constant parameter, so are measured only once during follow up in our daily clinical practice. Here we study the effect of diabetes over CCT, for a better understanding of the impact of diabetes over CCT.A comparative observational study of one and half years done among 106 diabetes and 106 non diabetic patients between 35 to 75 years old, attending ophthalmology OPD. CCT of both eyes was measured and mean CCT and was compared between diabetic and non-diabetic groups, among different subgroups of diabetic subjects and other parameters.CCT was thicker among diabetic groups (553.4434um) than non-diabetic groups (549.8491) but was not statistically significant according to our study. But there was statistically significant (p value 0.000165) thickening with increasing grades of diabetic retinopathy (DR) (mild DR (535.4524), moderate DR (543) and PDR (591.5)). Our study concludes that DM is associated with thicker cornea; hence CCT values can vary with time in DM. So repeated CCT measurements for corrected IOP values is advised and warranted in DM patients for proper management of IOP.

Comparative study of FLACS vs conventional phacoemulsification for cataract patients with high myopia.

To compare the short-term changes in cornea, retina, and choroid of femtosecond laser-assisted cataract surgery (FLACS) with conventional phacoemulsification (CPS) in high myopia patients with cataract. Affiliated Hospital of Nantong University, Jiangsu Province, China. Prospective single-center study. Demographics, ocular clinical features, ultrasound power, absolute phacoemulsification time, and effective phacoemulsification time were recorded for each patient. Endothelial cell density (ECD), central corneal thickness (CCT), corrected distance visual acuity (CDVA), intraocular pressure (IOP), center foveal thickness (CFT), subfoveal choroidal thickness (SFCT), and choroidal vascularity index (CVI) were evaluated preoperatively and at 1 week, 1 month, and 3 months postoperatively. Intraoperative parameters and intraoperative/postoperative complications were recorded. 97 eyes (46 eyes and 51 eyes in the FLACS and CPS groups, respectively) were included and analyzed. Effective phacoemulsification time was lower in the FLACS group compared with the CPS group ( P < .05). The increase in CCT was significantly lower in the FLACS group compared with the CPS group at 1 week and 1 month ( P < .05). CDVA and IOP were similar in both groups at the final visit ( P > .05). The ECD decreased was lower among CPS patients compared with FLACS patients. CFT, SFCT, and CVI increase in both groups but were increased more in the CPS group with high myopia patients. No serious complications occurred in either group. FLACS is a more safety and effective in cataract patients with high myopia. It has advantages in effectively reducing EPT and promoting faster recovery of the cornea, macular, and choroidal thickness.

Ocular toxicity of psychotropic medications in a tertiary hospital in Lagos, Nigeria.

Objective: This study aimed to determine the ocular toxicity of the psychotropic drugs used by patients and to proffer suggestions on how to prevent visual impairment or blindness in patients on antipsychotics. Methodology: This was a prospective, hospital-based cross-sectional study. Participants were adult patients between 18 and 70 years, diagnosed with psychosis, and who had been on antipsychotic medications for at least one year. All the recruited participants had an examination of the anterior and posterior segments of the eyes done. Schirmer's test, Tear film Break-up time (TBUT), Central Corneal thickness (CCT), Colour vision test, and Contrast sensitivity test were done. The collected data was analyzed using IBM SPSS 28.0. Results: The study enrolled patients who were mainly females (55.1%). The highest age group of the cases was 29-38 years (29.7%). The examination of the eyes and investigations revealed that 10.2% of the respondents on antipsychotics had color vision deficiency and 25.4% - loss of contrast sensitivity. Lid pigmentation was observed in 20.3% and cataract in 32.2%. Degeneration of the peripheral retina was observed in 4.2% of patients on antipsychotic medication. Schirmer's test showed mild, moderate, and severe dry eyes in 11%,17.8%, and 20.3% of the participants respectively. The test for Central Corneal Thickness (CCT) showed 50.0% of the respondents had a thin cornea and 24.6% had a thick cornea. 17.8% of the surveyed respondents manifested high eye pressure. Discussion: Psychotropics are the gold standard for the treatment of psychotic episodes and disorders. The choice of drug, dosing, and mode of administration depends on the severity of the psychotic disorder. Higher doses of psychotropics were reported to cause toxicity in different organs in the body including the eyes, especially on long-term use and high dosage and this can affect the quality of life of the individual negatively. Conclusion: The earliest and most prominent side effect seen in patients on psychotic medication was dry eyes. There were a few cases of blinding eye diseases like glaucoma, and cataract. For these reasons, ophthalmic assessments should be included as part of the management of psychiatric patients early at the start of antipsychotic treatment. Abbreviations: FGA = First Generation Antipsychotics, SGA = Second Generation Antipsychotics, TCAs = Tricyclic Antidepressants, CCT = Central Corneal Thickness, IOP = Intraocular Pressure, TBUT =Tear film Break-up Time, BIO = Binocular Indirect Ophthalmoscope.

Corneal Epithelial Thickness in Normal Corneas with Low and High Toricity

Abstract Purpose: To compare the corneal epithelial thickness along the flat and steep meridians of corneas with low and high toricity. Methods: This was a prospective observational comparative study on healthy subjects with normal corneas seeking preoperative evaluation for refractive surgery at a university-based hospital. Subjects with up to 2 diopters (D) of corneal with-the-rule astigmatism were defined as low corneal toricity (CT), whereas cylinder &gt; two-dimensional was considered as high CT. The anterior segment optical coherence tomography was conducted to measure the epithelial thickness along the principle meridians of CT over a diameter of 9 mm. At the eye level, outcome variables (corneal and epithelial thicknesses in low- and high-astigmatism groups) were assessed using generalized estimating equation models. Results: Included were 98 eyes (49 subjects): 46 eyes (23 subjects) with low CT and 52 eyes (26 subjects) with high CT. Two groups were similar with respect to the age (P = 0.82), sex (P = 0.49), and spherical equivalent (P = 0.11). Although the corneal thickness at steep and flat meridians was not different between two groups, high-CT group had significantly thinner epithelium at inferior 2.5–3.5 and 3.5–4.5 mm zones (P = 0.01 and 0.04) as well as superior 2.5–3.5 mm zone (P = 0.03) along the steep meridian. Two groups were similar with respect to epithelial thickness of flat meridian (all P &gt; 0.05). Conclusion: The epithelium of steep meridian was thinner in the high-CT group compared to the low-CT group.