Central Corneal Thickness Measurements Research Articles

Immediate Effects of Goldmann Applanation Tonometry on Central Corneal Thickness Measurements Using Contact and Non-contact Pachymetry Methods.

The objective was to evaluate the immediate impact of Goldmann Applanation Tonometry (GAT), a gold-standard intraocular pressure measurement technique, on the reliability of central corneal thickness (CCT) measurements and to compare the outcomes between contact and non-contact pachymetry methods. Fifty-one adult participants without ocular pathology were enrolled. Serial CCT measurements were conducted using three different pachymetry modalities across three days, both at baseline and post-GAT: Day 1 with an ultrasound pachymeter (USP), Day 2 using optical low-coherence reflectometry (OLCR), and Day 3 via anterior segment optical coherence tomography (AS-OCT). The study involved comparing mean CCT and CCT standard deviation at baseline and post-GAT using one-way analysis of variance (ANOVA) and paired t-tests. In the 610 CCT measurements performed, mean CCT did not show significant changes post-GAT overall or by modality (USP: +2.20 microns, p=0.63;OLCR: +1.0 microns, p=0.93;AS-OCT: +0.40 microns, p=0.95). However, contact USP consistently produced thicker corneal readings than non-contact OLCR and AS-OCT both at baseline and post-GAT (p < 0.0001). Notably, there was a significant increase in CCT standard deviation (+51.1%) and a decrease in adherence to technical repeatability specifications with contact USP following GAT (from 55% to 33%, p < 0.05). The study suggests that contact intraocular pressure measurement methods like GAT may influence the reliability and repeatability of CCT measurements, as observed in our increased CCT measurement standard deviations. This could have important implications for accurate diagnosis and treatment planning for various ocular conditions. Given the study's limited sample size, further research may be warranted.

Repeatability of pentacam AXL in determining axial length and ocular indices in people with irregular cornea

Aims/Purpose: To determine the repeatability of Pentacam AXL in determining ocular axial length and some corneal indices in people with irregular corneas.Methods: Ocular biometry using Pentacam AXL underwent in this study. The Pentacam AXL measurements were done 3 times 10‐minutes apart. To evaluate the repeatability, the intraclass correlation coefficient (ICC), were calculated.Results: In this study, 141 eyes of 141 individuals with irregular cornea aged 60 to 91 years (64 ± 15.7) were included. The ICC of axial length, flat keratometry, steep keratometry, anterior chamber depth, central corneal thickness and corneal diameter measurements were 0.957, 0.981, 0.989, 0.980, 0.923 and 0.981 respectively. In cases with long axial length (&gt;24.5mm) the ICC of axial length, flat keratometry, steep keratometry, anterior chamber depth, central corneal thickness and corneal diameter measurements were 0.427, 0.946, 0.993, 0.988, 0.861 and 0.989 respectively.Conclusions: The results of this study showed that generally Pentacam AXL has a high repeatability in measuring the axial length and some corneal indices of the eye in irregular corneas. However, it should be note that Pentacam AXL has no repeatability in irregular corneas with long axial length.

Effects of Prostaglandin Analogue on the Central Retinal Thickness in Patients with Type 2 Diabetes Mellitus

Purpose: To determine the central macular thickness in patients with type 2 Diabetes using Latanoprost eye drops and to compare with type 2 diabetic patients using Timolol eye drops. Study Design: Quasi experimental study. Place and Duration of Study: Al-Noaman Teaching Hospital from February 2023 to April 2023. Methods: One hundred diabetic patients were divided into two equal groups (Timolol group and Latanoprost group). Visual acuity was tested using Snellen chart, IOP was measured with Goldmann Applanation Tonometer, central corneal thickness (CCT) measurement was done to correct IOP for CCT. Optical coherence tomography (OCT) was used to measure central retinal thickness (CRT). Results: The mean age of Timolol group was 57.91±1.6 years, which was very close to the mean age of Latanoprost group (57.57±1.63 years). There were 30 females and 20 males in each group. HbA1Cwas 8.99±0.47% in Timolol and 6.28±0.08% in Latanoprost group (p &lt;0.001). The IOP showed statistically lower levels in Timolol group in comparison to Latanoprost group, 28.81±0.93 mmHg in comparison to 29.56±1.04 mmHg, respectively. In Timolol group, visual acuity significantly improved, the IOP was reduced, and the CRT was significantly lowered. However, in Latanoprost group, the pre and post treatment values showed that only the IOP significantly improved. Visual acuity and CRT were statistically and clinically the same. Conclusion: Latanoprost may increase the central retinal thickness in diabetic patients without diabetic macular edema, however the rationale for stopping the medication in low-risk patients is still lacking.

Comparison of ocular biometry and refractive outcomes using two swept-source optical coherence tomography-based biometers.

To evaluate the ocular biometry agreement and prediction of postoperative refractive outcomes obtained using two swept-source optical coherence tomography (SS-OCT) biometers: Anterion (Heidelberg Engineering, Heidelberg, Germany) and Argos (Alcon, Fort Worth, TX, USA). Ambispective analysis was conducted on 105 eyes at the Samsung Medical Center, Seoul, Republic of Korea, between June 2021 and March 2022. Biometric values were assessed using both devices before cataract surgery. Intraocular lens (IOL) power, mean arithmetic error (ME), and mean absolute error (MAE) were calculated using the Barrett Universal II, Haigis, and Hoffer Q formulas. Anterion showed statistically significantly greater axial length (AL), central corneal thickness (CCT), and lens thickness (LT) than Argos (p = 0.03, p < 0.001, and p = 0.032, respectively). There were no significant differences in measuring anterior chamber depth (ACD) (p > 0.05). Anterion showed flatter corneal curvature measurements than Argos (p < 0.001). The postoperative prediction errors differed for all three formulas (p < 0.001). Anterion results leaned towards a slightly myopic outcome due to hyperopic target refraction. In all three formulas, the MAE and percentage of eyes with a prediction error ≤ ± 0.5 D were not significantly different between the two devices. Although the differences are not clinically significant, the measurements of AL, CCT, and LT obtained with Anterion were greater compared to those measured with Argos, while the keratometry (K) and corneal diameter (CD) values were smaller. Consequently, this resulted in a minor difference in refractive predictability, with Anterion showing a slight tendency toward more myopic refractive errors. However, there were no significant differences in MAE or the percentage of eyes within ± 0.5D.

Agreement between Two Biometers for Central Corneal Thickness Measurement in High Myopia Patients

Background In refractive surgery, the measurement of Central Corneal Thickness (CCT) is a critical factor in the preparation and screening of surgery to correct myopia. CCT measurements can be measured by optical biometers, including the Scheimpflug camera and Swept-source Optical Coherence Tomography (SS-OCT). Aim This study aimed to compare the Central Corneal Thickness (CCT) measurements made with Swept-source Optical Coherence Tomography (SS-OCT)-based biometers and the Scheimpflug camera in patients with high myopia. Methods An analytical cross-sectional study was performed to evaluate the agreement between Central Corneal Thickness (CCT) values obtained using Swept-source Optical Coherence Tomography (SS-OCT) and the Scheimpflug camera. We included a total of 28 individuals with high myopia, including 44 eyes, for our study. These patients underwent Central Corneal Thickness (CCT) tests using both Swept-source Optical Coherence Tomography (SS-OCT) and the Scheimpflug camera. The Bland-Altman test was used to assess the agreement between the two devices. Results Forty-four eyes with axial lengths ranging from 26.05 to 34.02 mm based on SS-OCT examinations were included in this study. The mean CCT was 527.59 ± 35.710 (p &lt;0.05) μm and 525.64 ± 35.421 μm (p &lt;0.05), based on SS-OCT and the Scheimpflug camera, respectively. The Bland-Altman plot revealed good agreement between both devices, with a mean difference of 2.3409 μm; however, a 95% limit of agreement demonstrated a wide range, ranging from -8.48509 to 12.39400 μm at a 95% confidence interval. Conclusion CCT measurements using SS-OCT and the Scheimpflug camera differed significantly among patients with high myopia. Our findings have suggested that CCT measurements made with either device should be interpreted with caution and not be used interchangeably.

Association between Myopia and Central Corneal Thickness among Patients in a Tertiary Care PAF Hospital

Objectives Central corneal thickness (CCT) measurement is important in the estimation of intraocular pressure (IOP). It is also important when decision has to be made regarding refractive surgery. Studies conducted to determine the relationship between myopia and CCT have produced debatable outcomes. While some studies have found a negative correlation between CCT and the degree of myopia, many others have reported no significant correlation between the two. We attempt to study the relationship between them among patients attending the Ophthalmology department of a tertiary care hospital in Pakistan. Methods This was a prospective cross-sectional study that was conducted at the department of Ophthalmology, PAF Hospital, E9 Islamabad. The study was conducted over a period of four months, from March to June, 2024. Participants were enrolled using non-probability, consecutive sampling. The central corneal thickness was measured and compared in myopic and emmetropic patients. Results In this study we examined 100 eyes of 50 participants. 50 eyes were myopic while the other 50 were emmetropic. There was a statistically significant difference between these two means (P=0.009) and so CCT was found to be thinner in myopic patients. However, no correlation was seen between CCT and the degree of myopia (P=0.055). Our study found no significant relation between CCT and age or gender. Conclusion There is a statistically significant difference between the mean CCT of emmetropes and myopes, with myopic eyes having thinner corneas. However, no significant difference is seen in the CCT according to the degree of myopia.

Assessment of measurement variability across automated biometry devices.

To evaluate measurement variability between different readily available automated biometric devices for the purposes of improving surgeon decision making for phakic intraocular lens (IOL) sizing. Private practice (Houston, TX, USA). Prospective, single center, bilateral, non-randomized, open-label, observational study. This study included healthy eyes, with no prior eye surgery, and with a spherical equivalent of at least -1.00D. Orbscan II was compared to Argos, Atlas 9000, caliper, IOLMaster 500, IOLMaster 700, iTrace, Lenstar LS900, Pentacam HR, and Pentacam AXL Wave. Preoperative measurements included white to white (WTW), anterior chamber depth (ACD), and central corneal thickness (CCT). Linear mixed effect models were created to determine adjustment factor between the Orbscan II and other devices for WTW, ACD, and CCT measurements. A total of 204 subjects (408 eyes) completed the study. All mean WTW measurements were significantly different compared to the Orbscan II (p < 0.01), except for Pentacam AXL Wave. All mean ACD and CCT measurements were significantly different compared to the Orbscan II (p < 0.01). Adjustment factors for WTW ranged from -0.65 mm to 0.24 mm. Adjustment factors for ACD ranged from -0.21 mm to -0.16 mm. Adjustment factors for CCT ranged from 19.9 µm to -36.0 µm. The biometers tested were not interchangeable with the Orbscan II. Adjustment factors for WTW and ACD may compensate for differences between devices and adapt ICL sizing recommendations.

Agreement between a new fully automatic ocular biometer based on optical low-coherence reflectometry and an optical biometer based on Scheimpflug imaging combined with partial coherence interferometry

BackgroundTo analyze the difference and agreement between measurements obtained by a new fully automatic optical biometer, the SW-9000 μm Plus, based on optical low-coherence reflectometry (OLCR) and a commonly used optical biometer (Pentacam AXL) based on Scheimpflug imaging with partial coherence interferometry (PCI).MethodsThe central corneal thickness (CCT), anterior chamber depth (ACD, from epithelium to anterior lens surface), lens thickness (LT), mean keratometry (Km), corneal astigmatism, corneal diameter (CD), pupil diameter (PD), and axial length (AL) of 74 eyes (from 74 healthy subjects) were measured using the SW-9000 μm Plus and the Pentacam AXL to determine the agreement. Double angle plots were used for astigmatism vector analysis. Bland–Altman and 95% limits of agreement (LoA) were calculated.ResultsStatistically significant differences were detected for all parameters but J0 vector. The Bland–Altman analysis of AL, CCT, ACD, Km, CD, J0 and J45 indicated a high level of agreement between the two devices. Among AL, CCT, ACD, Km, J0, J45, CD, and PD, the 95% LoA ranged from -0.07 to 0.05 mm, -9.67 to 7.34 mm, -0.11 to 0.04 mm, -0.25 to 0.50 D, -0.22 to 0.20 D, -0.15 to 0.20 D, -0.23 to 0.35 mm and 1.55 to 3.77 mm, respectively.ConclusionsThe measurements of AL, CCT, ACD, Km, corneal astigmatism, and CD showed a narrow LoA and may be used interchangeably in healthy subjects between the new OLCR optical biometer and the Scheimpflug/PCI biometer; however, a poor agreement was noted for PD values.

Association between central corneal thickness and systemic lupus erythematosus: a cross-sectional study protocol.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease affecting multiple systems and classified under connective tissue disorders. Ocular involvement occurs in up to 30% of SLE cases, with the cornea being particularly susceptible to thinning due to immune-complex deposits and its predominantly type I collagen composition. This corneal thinning is clinically significant in glaucoma, where patients with reduced central corneal thickness (CCT) may have up to a threefold increased risk of developing glaucoma, as well as in refractive surgery. However, existing studies on CCT in SLE are limited and marked by substantial heterogeneity in methodology, technology, criteria, and participant numbers, resulting in conflicting findings. Based in our hypothesis that SLE-related corneal lysis may result in decreased CCT, this study aims to determine and compare the mean CCT values between SLE patients and healthy controls to obtain a more precise understanding of the potential relationship. A cross-sectional observational study will be conducted, enrolling SLE patients and age-and sex-matched healthy controls recruited from ophthalmology consultations. Exclusion criteria will be applied to rule out other corneal thinning risk factors. A pilot study estimated a minimum sample size of 34 participants per group. CCT measurements will be obtained using Zeiss HD Cirrus 5,000 optical coherence tomography (OCT) on a randomly selected eye, following concordance analysis using the Kappa index. Statistical analysis will include descriptive, bivariate, and multivariate methods. The study protocol was approved by the ethics committee. The cornea's vulnerability to thinning and lysis in SLE, which impacts CCT, is crucial for the accurate assessment of glaucoma, the leading cause of irreversible blindness worldwide and the second leading cause in Europe. Given that patients with reduced CCT are at a significantly higher risk of developing glaucoma, further research is necessary to understand the association between SLE and CCT. Our study aims to enhance methodological rigor compared to prior research by determining an appropriate sample size and exclusively enrolling SLE patients to increase participant homogeneity. If a significant difference in CCT between groups and an association between CCT and SLE are found, a prospective study will be considered.

Comparison between Goldmann Applanation Tonometry and Air Puff Tonometry for Measurement of Intraocular Pressure in Siliconized Eyes

Abstract Background Silicone oil (SO) has been a part of vitreoretinal surgery since the 1960s. The use of silicone oil in conjunction with advanced vitreous surgical techniques can successfully treat complicated retinal detachment (RD). Aim of the Work to compare the intraocular pressure (IOP) measurements following Pars Plana Vitrectomy (PPV) with injection of Silicone Oil (SO) by Goldmann applanation tonometry (GAT) and noncontact Air Puff Tonometer (APT). Patients and Methods This study included a total of 165 eyes of 165 patients. Of these 165 patients, 110 have undergone PPV and silicone oil injection, while the remaining 55 participants served as the control group. Results The participants in our study were divided into a control group, and a siliconized group which was subdivided into SO 1000 cSt (Group A) and SO 5000 cSt (Group B). The control group had an average age of 50.65±12.26 years, Group A had an average age of 53.53±12.04 years, and Group B had an average age of 55.45±12.02 years. The control group in our study consisted of 28 males (50.9%) and 27 females (49.1%), while Group A had 37 males (67.3%) and 18 females (32.7%), and Group B had 38 males (69.1%) and 17 females (30.9%). Central corneal thickness (CCT) was measured for all participants. The average CCT was 536.53±28.66µm for the control group, 531.67±29.19µm for Group A, and 527.13±28.79µm for Group B. There was no statistically significant difference in the CCT measurements between the study groups (P = 0.410). The average IOP values were obtained using both the airpuff tonometer (APT) and Goldmann applanation tonometry (GAT) methods. In the control group, the average IOP was 16.56±2.98 mmHg using APT and 15.27±2.73 mmHg using GAT. For Group A, the average IOP was 17.09±7.0 mmHg with APT and 15.61±6.43 mmHg with GAT. In Group B, the average IOP was 16.71±4.93 mmHg using APT and 15.13±4.63 mmHg using GAT. The P-value was &amp;gt;0.05 in all groups, indicating that the differences were not statistically significant. Conclusion the results showed a correspondence between the Goldmann applanation tonometer (GAT) and the airpuff tonometer (APT) in siliconized eyes. The differences in intraocular pressure (IOP) measurements between the two instruments were minimal and not statistically significant, with APT measurements being slightly higher than GAT measurements. The study also concluded that there is a greater chance of increased IOP following pars plana vitrectomy (PPV) and silicone oil (SO) injection with SO 1000 cSt compared to 5000 cSt, but this difference was not statistically significant. Furthermore, this IOP difference between the two methods was not correlated with age, gender, CCT, or lens status of the patients. Thus, there is good agreement between the two methods.

Optical coherence tomography angiography analysis of the fellow eye in unilateral pseudoexfoliation syndrome

PurposeTo compare the macular and optic disc vascular parameters in the unaffected fellow eyes of subjects with unilateral pseudoexfoliation syndrome (PXS) and controls using optical coherence tomography angiography (OCTA).MethodsThe medical records of 61 eyes of 61 patients were analyzed in a retrospective study. Of these, 30 eyes were unaffected fellow eyes and 31 eyes were control eyes. The vessel density (VD), perfusion density (PD) and foveal avascular zone (FAZ)-related parameters of the superficial capillary plexus (SCP) in the circumpapillary and macular area and the VD and PD of the deep capillary plexus (DCP) in the macular area were measured using OCTA after dilatation and were compared between two groups after adjustment for age, sex and axial length.ResultsThere were no statistically significant differences in sex ratio or mean age, central corneal thickness measurements, refractive errors, intraocular pressures and axial length between both groups (all P > 0.05). In the circumpapillary area, inferior VD and PD in the inner zone, as well as average, temporal, inferior, and nasal VD and PD in the outer zone were significantly reduced in the unaffected fellow eyes with unilateral PXS, while the circumpapillary retinal nerve fiber layer (RNFL) thicknesses were similar between groups. In the macular SCP, VDs were significantly lower in all sectors in the inner area and in the outer zones (p < 0.05 for all), PDs were significantly lower in all sectors (p < 0.05 for all) except the nasal sector of the outer zone (p = 0.003 for average, p = 0.029 for superior sector, p = 0.004 for temporal sector, p < 0.001 for inferior sector), and the FAZ circularity (p = 0.037) were significantly lower in the unaffected fellow eyes with unilateral PXS, whereas macular ganglion cell inner plexiform layer (GCIPL) thickness was similar between the two groups.ConclusionsAlthough circumpapillary RNFL and GCIPL thicknesses were similar between the two groups, VDs and PDs in the circumpapillary and macular SCP and FAZ circularity were significantly lower in the fellow eye of subjects with unilateral PXS.

Behavior of biometric parameters during clinical hours

Purpose: To evaluate and quantify variation of biometric parameters - axial length (AL), anterior chamber depth (ACD), central corneal thickness (CCT) and white-to-white (WTW).Methods: A population-based retrospective cohort study was performed on patients who underwent a biometry test prior to cataract surgery using the IOL Master 700 (Carl Zeiss Meditec, Jena, Germany) between the years 2017-2021. Differences in these parameters were evaluated between scans executed at different times of the day.Results: 21,975 examinations of 8,611 patients were included. Mean age was 70.50±12.56 years. The mean time of the biometry exams was 10:52±1:23 AM. Measurements of AL, ACD, CCT and WTW were tested hourly and grouped between 7:00-9:00 AM and 12:00-03:00 PM.All the parameters showed a diurnal increase with a significance of p<0.001 (AL from 23.64±1.5 to 24.01±1.76mm; ACD from 3.29±0.67 to 3.35± 0.64mm; CCT from 0.52±0.04 to 0.53±0.04 µm and WTW from11.83±0.46 to 11.90±0.51mm). The most significant change was seen in AL.The difference between time groups remained significant in a generalized linear mixed model (P<0.001).Conclusions: There are fluctuations in AL, ACD, CCT, WTW measurements during office hours. These results raise questions about the significance of timing of the biometry exam and the effect on the ELP calculation.

A comparative study of central corneal thickness using an ultrasonic pachymeter and a noncontact specular microscope in adult patients coming to the ophthalmology outpatient department in a tertiary care hospital in Western India

Objective:To evaluate and compare the accuracy of measuring central corneal thickness (CCT) using an ultrasonic pachymeter and a noncontact specular microscope and whether they can be used interchangeably in adult patients with healthy cornea.Methodology:A comparative and observational study was carried out in adult patients coming to the ophthalmology outpatient department (OPD) in a tertiary care hospital in Western India. In all patients, CCT is measured using an ultrasonic pachymeter and a noncontact specular microscope to perform a comparative study. Statistical analysis was done using pairedt-test. Two-tailed hypothesis was applied.Results:This study included a sample size of 300 eyes of 150 adult patients. We want to test whether CCT values by Ultrasound Pachymeter and Noncontact specular Microscope is significantly different for right eyes and left eyes of the same patients, therefor we applied pairedt-test for statistical analysis.Tvalue for the right eye CCT measurement was −0.4 and the value ofPwas 0.69.Tvalue for the left eye CCT measurement was −0.79 and the value ofPwas 0.43.P&gt; 0.05 suggested that the results were nonsignificant.Conclusion:Our study suggests that the noncontact specular microscope produces CCT values that do not vary significantly from ultrasonic pachymeter. In subjects with healthy cornea, ultrasound pachymeter and specular microscope can be used interchangeably.

Introduction and Validation of Low-Cost Ocular Biometry in Healthy and Cataractous Eyes Using a Thermally Tunable Swept-Source Laser

To introduce and validate a novel substantially lower-priced and rapid swept-source investigational optical biometer in healthy and cataractous eyes, using a thermally tuned laser diode used extensively in cell phones and data communication as an alternative swept source. Prospective accuracy, validity, and reliability analysis. A total of 60 eyes of 59 subjects (29 eyes of 29 healthy subjects and 31 eyes of 30 cataract patients) were enrolled in a prospective comparative study at the Vienna General Hospital between August 2021 and April 2023. Averaged intraocular distances were acquired in 2.5 seconds from datasets consisting of 5000 consecutive A-scans at a single position by a low-cost swept-source optical biometry (SSOB) system. Instrument repeatability was assessed via standard deviations (SDs) and coefficients of variation (CoVs) of parameters such as axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). Healthy subjects and cataract patients were subsequently measured on the same day with the SSOB and a referential partial coherence interferometry (PCI) biometer (IOLMaster 500) to establish AL inter-device correlation (r) for instrument calibration. AL and ACD as shared parameters between both biometers were evaluated for their limits of agreements (LoA) using Bland-Altman analysis. Repeated measurements of AL, ACD, LT, and CCT revealed SDs of 18 µm, 12 µm, 12 µm, and 10 µm, respectively. All parameters except for CCT had a COV <1%. Except for 1 eye with white cataract, 59 eyes of 59 study participants with various degrees and types of cataract could be measured with both devices. The AL inter-device correlation was excellent (r > 0.99). The 95% LoAs between both biometers were -0.14 to 0.13 mm for AL and -0.28 to 0.25 mm for ACD. Optical biometry using a thermally tunable VCSEL swept-source light source has the potential to provide clinically relevant biometric parameters at an unprecedented 100-fold lower price point than currently used state-of-the-art optical biometers, paving the way for compact devices in remote care settings.

Low-cost do-it-yourself (DIY) kit for glaucoma procedures.

Surgical skill training in ophthalmology is pivotal for ensuring optimal and safe patient outcomes. Access to traditional training resources such as cadaveric or animal eyes, as well as modern alternatives such as silicone eyeballs and simulators, remains limited, especially in resource-constrained settings. We present a series of innovative and low-cost do-it-yourself (DIY) models for glaucoma training using readily available hospital waste materials. These models allow ophthalmic assistants, fellows, and junior consultants to practice various procedures before transitioning to live patients, thereby enhancing surgical proficiency and minimizing the financial burden on both trainees and training institutions. We were able to practice procedures such as tonometry, central corneal thickness measurement, laser suture lysis, laser iridotomy, anterior chamber decompression, bleb needling, trabeculectomy flap construction, and suturing. By providing a practical and easy training solution, these models have the potential to boost confidence among glaucoma trainees and thus address the growing demand for skilled glaucoma surgeons.

Comparison of central corneal thickness measured in myopic eyes by Pentacam, Sirius and IOLMaster 700

PurposeThe purpose of this study was to evaluate the correlations and consistency among the central corneal thickness (CCT) of healthy myopic patients measured with three different anterior segment analysis systems. DesignThis was a retrospective study. The study included myopia patients who had undergone preoperative examinations in the refractive surgery department of our hospital between January 2021 and December 2023. The CCT was measured separately using Pentacam, Sirius, and IOLMaster 700. MethodsStatistical analysis was conducted using SPSS software. Correlations among the three groups of measured values were assessed using the Pearson method, and a simple scatter plot and fitting line were drawn. Bland‒Altman scatter plots and 95 % limits of agreement (LoAs) were used to evaluate consistency in the data among the systems. ResultsA total of 269 patients participated in the study, including 134 males (49.8 %) and 135 females (50.2 %). The CCT measurements by Pentacam, Sirius, and IOLMaster 700 instruments were found to be 541.63 ± 31.67 μm, 541.74 ± 33.36 μm, and 548.90 ± 34.19 μm respectively; significant differences were observed among these measurements (p < 0.05). Significant differences were also observed in CCT between Pentacam and IOLMaster 700 as well as between Sirius and IOLMaster 700 (p < 0.05). The CCT measurements by all three devices showed high positive correlation with all p values less than 0.001: Pentacam and Sirius, r = 0.972; Pentacam and IOLMaster 700, r = 0.966; and Sirius and IOLMaster 700, r = 0.962. The respective 95 % LoAs were -0.18∼0.18; -1.51∼-1.11; and -1.52∼-1. ConclusionThe results indicate that there is a high correlation in measuring CCT for healthy myopic eyes using three different anterior segment analysis systems. However, the differences in the values measured by the three devices were statistically significant. Therefore, in actual clinical practice, it is suggested that the same device should be used to measure and evaluate the CCT across visits.

Comparison of axial length and anterior segment parameters of patients with myopia measured using 2 fourier-domain optical coherent biometry devices

BackgroundThis study assessed the agreement of ocular parameters of patients with myopia measured using Colombo intraocular lens (IOL) 2 and IOLMaster 700.MethodsEighty patients (male, 22; average age, 29.14 ± 7.36 years) with myopia (159 eyes) were included in this study in May 2023. The participants’ axial length (AXL), central corneal thickness (CCT), lens thickness (LT), white-to-white distance (WTW), front flat (K1), steep (K2), mean (Km) corneal keratometry, astigmatism (Astig), J0 vector, and J45 vector were measured using the IOLMaster 700 and Colombo IOL 2. The measurements from both devices were compared using the generalized estimating equation, correlation analysis, and Bland-Altman plots.ResultsWith the Colombo IOL 2, lower values for K2 and J0 (odds ratio [OR] = 0.587, p = 0.033; OR = 0.779, p < 0.0001, respectively), and larger values for WTW, Astig, and J45 (OR = 1.277, OR = 1.482, OR = 1.1, all p < 0.0001) were obtained. All ocular measurements by both instruments showed positive correlations, with AXL demonstrating the strongest correlation (r = 0.9996, p < 0.0001). The intraclass correlation coefficients for AXL and CCT measured by both instruments was 0.999 and 0.988 (both p < 0.0001), and Bland-Altman plot showed 95% limits of agreement (LoA) of -0.078 to 0.11 mm and − 9.989 to 13.486 μm, respectively. The maximum absolute 95% LoA for LT, WTW, K1, K2, and J0 were relatively high, achieving 0.829 mm, 0.717 mm, 0.983 D, 0.948 D, and 0.632 D, respectively.ConclusionsIn young patients with myopia, CCT and AXL measurements obtained with the Colombo IOL 2 and IOLMaster 700 were comparable. However, WTW, LT, corneal refractive power, and astigmatism values could not be used interchangeably in clinical practice.

The impact of systemic isotretinoin treatment on the tear film, meibomian glands, and corneal endothelium

Purpose The study aims to investigate changes in tear function, meibomian glands and corneal endothelium in patients receiving systemic isotretinoin therapy. Materials and methods This prospective study included 38 eyes from 38 patients (23 females and 15 males) treated with systemic isotretinoin (0.5–1 mg/kg/day) following the diagnosis of acne vulgaris. All patients underwent a comprehensive ophthalmologic examination at baseline, 1st month, and third month of treatment. Subjective complaints were assessed using the Ocular Surface Disease Index (OSDI). Tear functions were evaluated through non-invasive tear break up time (NIBUT) and Schirmer I test. Meibomian gland (MG) changes were examined using meibography. Corneal parameters, including endothelial cell density (ECD), coefficient of variation (CV), the number of cells with a hexagonal shape (6A), average cell area (AVG), and central corneal thickness (CCT) were assessed using non-contact specular microscopy. Results The mean age of the patients was 19.29 ± 2.83 years. Ocular surface-related discomfort, measured with OSDI scores, significantly worsened at the third month measurements compared to the pre-treatment values (p < 0.001). In the 1st month of treatment, there was a significant decrease in NIBUT (p < 0.05). No statistically significant difference was found in the Schirmer test results at each visit. According to the 1st and third-month analysis, there was a significant increase in MG loss compared to the pre-treatment period (p < 0.001). ECD, CV, 6 A, AVG measurements at the first and third months showed a significant change compared to the pre-treatment values (p < 0.001). No significant difference was observed in the CCT measurements during the treatment. Conclusion Systemic isotretinoin disrupted tear stability, caused MG loss, deterioration in corneal endothelium, and led to symptomatic complaints in patients.

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.

Intrasession repeatability and agreement of the anterior corneal assessment provided by a multidiagnostic device

ABSTRACT Clinical relevance Multidiagnostic systems have recently appeared on the market. Knowledge of the repeatability and validity of any instrument is mandatory before its introduction in clinical practice. Background The aim of this work is to examine the intrasession repeatability of anterior pole measurements provided by the multidiagnostic device Wave Analyzer Medica 700 (WAM700) and agreement with Pentacam measurements in normal eyes. Methods In the right eyes of 113 participants, three repeat measurements of central keratometry, central corneal thickness, anterior chamber depth and corneal eccentricity were made with the WAM700 and Pentacam in random order. Intrasession repeatability and agreement were determined. Results Employing WAM700, intrasession repeatability for keratometry, central corneal thickness and anterior chamber depth was good (ICCs ≥ 0.992; CV 0.48–0.98%), yet worse than the values obtained for the Pentacam (ICCs ≥ 0.998; CV 0–0.33%). WAM700 showed excellent intrasession repeatability when used to measure the anterior chamber depth (Sw 0.03 mm). However, the repeatability of this device was inferior for central corneal thickness (Sw 4.24 μm) and keratometry measurements (Sw < 0.21 D) and was poor for corneal eccentricity (Sw 0.07; ICC 0.908; CV 14.58%). Agreement between WAM700 and Pentacam showed a high ICC for the keratometry measurements, central corneal thickness and anterior chamber depth (>0.972) but lower for corneal eccentricity (ICC 0.762). Conclusions In healthy eyes, the WAM700 multidiagnostic device showed good intrasession repeatability for keratometry, central corneal thickness and anterior chamber depth measurements. Agreement between WAM700 and Pentacam was good for the anterior chamber depth measurement. However, these instruments cannot be considered interchangeable for keratometry, central corneal thickness and eccentricity readings.