Changes In Corneal Thickness Research Articles

Effects of corneal epithelial remodeling on corneal asphericity after FS-LASIK and Trans-PRK: A prospective study.

To observe the changes in corneal epithelial thickness after FS-LASIK and Trans-PRK surgery and to investigate the impact of corneal epithelial remodeling on Q-value and HOA. In this prospective cohort study, 50 patients (100 eyes) underwent FS-LASIK and 45 patients (90 eyes) underwent Trans-PRK. Anterior segment OCT was used to measure the corneal epithelial thickness in different corneal zones (central zone: 0-2 mm; paracentral zone: 2-5 mm; and mid-peripheral zone: 5-6 mm) preoperatively and postoperatively at 1 week, 1 month, 3 months, and 6 months. The correlation between ΔCET in the superior, nasal, inferior, and temporal region at 6 months postoperatively and ΔQ and ΔHOA was analyzed. At 6 months postoperatively, the epithelial thickness increased in the central, paracentral, and mid-peripheral zones in FS-LASIK and Trans-PRK. Central epithelial thickness and different regions of the paracentral zone and mid-peripheral exhibited significant thickening (P < 0.001). In the para-central zone and mid-peripheral zone, the ΔCET in different regions after LASIK and Trans-PRK was positively correlated with ΔQ (P < 0.05) and ΔHOA (P < 0.05). After FS-LASIK and Trans-PRK, significant epithelial thickening was observed. Epithelial changes in different regions lead to different Q-values in different regions and have different effects on HOA. This has a certain guiding significance for the design of refractive surgery, and minimizing the increase of Q-value may improve the postoperative visual quality.

Corneal Epithelial Remodeling After Hyperopic SMILE: A 4-Year Study.

The purpose of this study was to investigate dynamic changes in corneal epithelial thickness (ET) after hyperopic small incision lenticule extraction (SMILE). This observational study included 18 eyes of 16 patients who were scheduled for hyperopic SMILE. High-resolution spectral-domain optical coherence tomography and a custom image segmentation algorithm were applied to measure corneal dynamic ET over a central 6 mm area. ET was analyzed among different corneal sectors (central, pericentral, and peripheral) at baseline and multiple postoperative time points (1 day, 1 month, 6 months, 2 years, and 4 years). Correlation analysis was performed between ET changes and preoperative and intraoperative parameters. The mean spherical equivalent of hyperopia correction was +2.64 ± 1.00 D, and the average age of enrolled 16 patients was 32.4 ± 10.8 years. At the last follow-up, 72% of eyes kept or improved corrected distance visual acuity, with 2 eyes that lost 2 lines. 72% of eyes were within ±1.0 D of target refraction, and 56% were within ±0.5 D. Average ET decreased by 11.0% (5.9 ± 2.3 μm) from 53.2 ± 3.5 μm to 47.4 ± 4.2 μm 4 years postoperatively (P<0.001). The ET at center 2 mm decreased most significantly by 14.5% (7.9 ± 2.9 μm), followed by the pericentral area by 10.5% (5.6 ± 2.3 μm). ET and front corneal curvature stabilized 1 month after surgery. No correlation was found between refraction regression and ET changes. Hyperopic SMILE induced significant central ET thinning. ET remodeling in the 6 mm area stabilized after 1 month and did not underlie refractive changes.

Changes in Corneal Endothelial Cells and Central Corneal Thickness in Pseudoexfoliation Syndrome

Purpose: The aim of the research is to investigate the impact of pseudoexfoliation syndrome (PEX) on corneal endothelial cells and central corneal thickness. Methods: In this analytic case-control study, the research sample included 60 patients (120 eyes), which was divided into two groups: the PEX group, 30 patients (60 eyes) obtained inclusion criteria and the control group, 30 patients (60 eyes) for result comparison, from patients visiting the ophthalmic clinic at Tishreen University Hospital. PEX degree was assessed using a slit lamp and the morphology of endothelial cells: endothelial cell density (ECD), coefficient of variation (COV) , percentage of hexagonal cells (EX%), average cell area (Avg.Cell Area) and central corneal thickness (CCT) were assessed using a specular microscope. Results: The average of ECD was lower in the PEX group compared with the control group (p-value = 0.0001). The average of EX% was lower in the PEX group compared with the control group (p-value = 0.0001). No statistically significant differences were observed between the research groups in COV values (p-value = 0.9). The Avg.Cell Area was higher in the PEX group compared with the control group (p-value = 0.003). The average of CCT was lower in the PEX group compared with the control group (p-value = 0.04). Conclusion: Corneal endothelial cells morphology and central corneal thickness are affected in eyes with PEX syndrome, and these changes increase with the severity of PEX.

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Longitudinal assessment of the progression of severe keratoconus based on corneal topography

We aimed to assess long-term disease progression in patients with severe keratoconus (KC). Clinical records of 125 patients (201 eyes) with severe KC followed-up for > 12 months were retrospectively analyzed. From these, 28 patients (31 eyes) were included. Corneal topography parameters evaluated included thinnest corneal thickness (TCT), maximum keratometry (Kmax), anterior and posterior mean corneal radii of 3 mm (aKM, pKM), steep keratometry, and KC screening indices. All patients wore rigid gas permeable contact lenses (RGPCLs) for an extended period. The median patient age and follow-up period were 20 (interquartile range [IQR] 17–22) years and 25 (15–38) months, respectively. Compared to baseline, the aKM, Kmax, and KC screening indices on the anterior corneal surface were reduced at the final follow-up (P < 0.05). No changes were observed in RGP-corrected visual acuity, TCT, pKM, or KC screening indices on the posterior corneal surface. The higher the baseline value, the greater the reduction in aKM and Kmax. Five patients (16%) experienced disease progression during follow-up. Patients with severe KC showed reduced anterior corneal surface curvature and no change in corneal thickness during an average follow-up period of 2–3 years while wearing RGPCLs.

Safety and prognosis of phacoemulsification using active sentry and active fluidics with different IOP settings - a randomized, controlled study

PurposeTo explore the impact of different intraoperative intraocular pressure (IOP) settings on the safety and prognosis in phacoemulsification.MethodsAge related cataract patients who met the inclusion criteria and underwent phacoemulsification by using active sentry handpiece and active fluidics system. According to different intraoperative IOP settings during surgery, they were randomly divided into two groups: the 20mmHg group and the 60mmHg group. The best corrected visual acuity (BCVA), cumulative dissipated energy (CDE), total U/S time, active surge mitigation (ASM), estimated fluid usage (EFU) as well as the changes in corneal thickness (CT), corneal epithelial layer thickness (CELT) and endothelial cell density (ECD) were collected. The post-operative follow-up was only 1 day.ResultsA total of 110 cases (110 eyes) were included in the study. There were 55 eyes in each group. There was no statistically significant difference in postoperative BCVA (p = 0.839). The CDE, total U/S time and EFU during surgery were (5.22 ± 3.31), (30.60 ± 15.06), (45.07 ± 12.68) and (4.70 ± 2.83), (27.39 ± 13.75), (42.38 ± 11.93) in the 20mmHg group and 60mmHg group (p = 0.381, 0.246, 0.254). The ASM during surgery in the 20mmHg group and 60mmHg group were (0.95 ± 2.77) and (7.24 ± 6.34), respectively. The 20mmHg group showed a significant decrease in ASM (p < 0.001). There was no statistically significant difference in the changes in CT, CELT and ECD before and after surgery between the two groups (p = 0.913, 0.825, 0.624). Both groups did not experience any intraoperative complications, such as posterior capsule rupture.ConclusionA lower IOP setting of 20 mmHg can significantly reduce the occurrence of intraoperative surges during phacoemulsification. And there was no increase in rate of complications.Trial RegistrationThe trial registration number is ChiCTR2100050240. The registered date is August 24th, 2021.

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.

A Comparison of Functional Endothelial Changes between Phacoemulsification with PCIOL and Manual Small Incision Cataract Surgery with PCIOL

Intraocular surgery e.g., cataract surgery with PCIOL implantation is one of the leading causes of corneal endothelial injury and change in the functionality of the cornea. This observational study was conducted in the Department of Ophthalmology of Combined Military Hospital (CMH), Dhaka Cantonment, Dhaka, Bangladesh, between January and July of 2016, to assess and compare functional changes in cornea (i.e., endothelial thickness) after phacoemulsification with posterior chamber intraocular lens (PCIOL) implantation and manual small incision cataract surgery (MSICS) with PCIOL implantation. A total of 80 patients of age-related cataract were randomly selected based on inclusion and exclusion criteria. All patients underwent complete ophthalmic evaluation pre- and post-operatively (at day 1, after 1 week and 3 months) specifically for observation of the endothelial changes in cornea. Specular microscopy was done to assess corneal endothelial change. The mean central corneal thickness was increased at day 1 (564.71±22.45μ vs. 555.10±40.57μ), after 1 week (539.43±22.16μ vs. 535.08±38.87μ) and 3 months (523.49±21.29μ vs. 520.05±33.68μ) after phacoemulsification and MSICS from their preoperative value (508.72±23.96μ vs. 503.62±32.06μ) respectively. However, the differences were not statistically significant between two groups (P&gt;0.05). The mean percentage of central corneal thickness change at day1, after 1 week and after 3 months following cataract surgery were found 11.01±6.30% and 10.22±26.54% at day 1, 6.04±7.52% and 6.25±21.24% after 1 week, 2.90±11.14% and 3.26±5.05% after 3 months in phacoemulsification and MSICS cases respectively. However, no statistically significant difference was observed in percentage of central corneal thickness change of both groups (P&gt;0.05). To summarize, an increased central corneal thickness was observed after phacoemulsification and SICS from their preoperative values. Mugda Med Coll J. 2024; 7(1): 14-18

Corneal endothelium and central corneal thickness changes in patients with type 2 diabetes mellitus

Background Understanding the effect of diabetes mellitus on the corneal endothelium is essential for developing effective strategies for early detection, monitoring, and management of diabetic eye disease. Aim The aim of this study was to investigate the changes in corneal endothelium and central corneal thickness (CCT) in patients with type 2 diabetes mellitus. Patients and methods This is a prospective, nonrandomized, comparative study that included 500 eyes of 500 participants that were divided into two groups: group A: 250 eyes of type 2 diabetic patients and group B: 250 eyes of healthy controls. The diabetic group was further subdivided into two subgroups based on the duration of diabetes (&lt;10 years and &gt;10 years) and glycemic control (uncontrolled diabetes and controlled diabetes). Specular microscopy was performed in all eyes. Results The CCT was significantly higher in the diabetic group (516.93±36.43 μm) than in the control group (503.47±41.89 μm) (P=0.001). However, the two groups were relatively similar in cell density (CD) (cells/mm2), coefficient of variation (%), and hexagonality, with no statistically significant differences (P&gt;0.05 for all). The CD was significantly higher in the patients with a duration of diabetes less than 10 years than those with a duration more than 10 years (2834.04±268.54 vs. 2277.13±244.54 cells/mm2, respectively, P=0.001). In addition, the hexagonality was significantly less in those with the duration of diabetes of more than 10 years (P=0.005). The CD was significantly less in the uncontrolled group than in the controlled group (2292.27±263.4 vs. 2644.69±370.88 cells/mm2, respectively, P=0.001). Conclusion Diabetic patients may exhibit alterations in their corneal parameters, particularly the CCT and endothelial CD. These changes are more in diabetic patients with a disease duration of more than 10 years and those with poor glycemic control.

Influence of midday removal and re-application of a scleral lens on fluid reservoir thickness, pre-lens tear film quality and visual acuity

PurposeTo investigate whether the midday removal and re-application of scleral lenses (SL) influences fluid reservoir (FR) thickness, pre-lens tear film quality and visual acuity. MethodsTwo clinical experiments were conducted. A total of 49 keratoconic eyes were evaluated for Part1(tear film and visual acuity analysis) and 12 keratoconic eyes for Part2 (FR thickness analysis). All subjects were wearing 16.4 mm SL for more than 12-months. Tear Film Surface Quality (TFSQ) was evaluated with Medmont E300 at more than 120 min of SL wear, 10 min after SL removal (pre-corneal TFSQ) and 5 min after re-apply the same SL. High and Low Contrast Visual Acuity (HCVA and LCVA) were also assessed with the SL on eye (before and after re-application). For Part2, Anterior OCT (MOptim MOcean4000, China) measurements were taken with and without the SL (at the same time points of Part1) and three outcomes were evaluated: FR thickness, SL thickness (control measurement) and corneal thickness. ResultsRemoving and re-applying a SL had a statistically significant positive impact on TFSQ, with an improvement from 0.26 ± 011 to 0.16 ± 0.08 (p = 0.001). This was accompanied by a statistically significant improvement in LogMAR HCVA (from 0.10 ± 0.09 to 0.08 ± 0.08, p < 0.001) and LCVA (from 0.39 ± 0.13 to 0.36 ± 0.13, p < 0.001). Regarding Part2 of the study, a statistically significant increase in FR thickness was observed after SL re-application (from 223.64 ± 48.08 µm to 267.81 ± 80.03 µm, p = 0.007). No changes in corneal thickness were observed. ConclusionsMidday removal and re-application of a scleral lens positively impacted pre-lens tear film surface quality, although the observed improvement in visual acuity does not constitute a clinically significant change. Clinicians should consider that removing and reapplying a scleral lens may result in an overestimation of the fluid reservoir thickness, which could affect clinical assessments and treatment decisions.

Assessment of the Predictive Ability of Theranostics for Corneal Cross-linking in Treating Keratoconus: A Randomized Clinical Trial

PurposeTo validate the ability of theranostic imaging biomarkers in assessing the propensity of corneal cross-linking (CXL) in flattening the maximum keratometry (Kmax) index. DesignProspective, randomized, multicenter, masked clinical trial (NCT05457647). ParticipantsFifty patients with progressive keratoconus. InterventionParticipants were stratified to undergo epithelium-off (epi-off; 25 eyes) and epithelium-on (epi-on; 25 eyes) CXL protocols using UV-A medical device incorporating theranostic software module. The device used controlled UV-A light both for performing CXL and for estimating the corneal riboflavin concentration (riboflavin score) and assessing treatment effect (theranostic score) in real time. A 0.22% riboflavin formulation was applied onto the cornea for 15 minutes and 20 minutes in epi-off and epi-on protocols respectively. All eyes underwent 9 minutes UV-A irradiance at 10 mW/cm2. Main Outcome MeasuresThe primary outcome measure was validation of the combined use of theranostic imaging biomarkers through measurement of their accuracy (proportion of correctly classified eyes) and precision (positive predictive value) to correctly classify eyes and positively predict a Kmax flattening at 1 year after CXL. Other outcome measures were the change of Kmax, endothelial cell density, uncorrected and corrected distance visual acuity, manifest spherical equivalent refraction, and central corneal thickness one year after CXL. ResultsAccuracy and precision of the combined use of theranostic imaging biomarkers in predicting eyes that had more than 0.1 diopter (D) Kmax flattening at 1 year were 91% and 95% respectively. The Kmax value significantly flattened by a median of -1.3 D (IQR: -2.11, -0.49 D; P < 0.001); both the uncorrected and corrected distance visual acuity improved by a median of -0.1 LogMAR (IQR: -0.3, 0.0 LogMAR; P < 0.001 and IQR: -0.2, 0.0 LogMAR; P < 0.001 respectively). There were no significant changes in endothelial cell density (P = 0.33) and central corneal thickness (P = 0.07) 1 year postoperatively. ConclusionsThe study demonstrated the efficacy of integrating theranostics in a UV-A medical device for the precise and predictive treatment of keratoconus with epi-off and epi-on CXL protocols. The concentration of riboflavin and its UV-A light mediated photo-activation in the cornea are the primary factors determining CXL treatment efficacy.

Corneal thickness and endothelial change after use of ocular hypotensive agents.

Corneal transplantation can restore visual function when visual impairment is caused by a corneal disease. However, this treatment is associated with the scarcity of cornea donors. The suitability of corneal donation from patients with glaucoma using ocular hypotensive agents (OHAs) is controversial. This study aimed to elucidate changes in corneal thickness, corneal endothelial cell density, and corneal endothelial cell hexagonality after OHA use in patients with primary open-angle glaucoma. We retrospectively reviewed the data of 53 glaucoma suspect eyes without OHA use and 106 primary open-angle glaucoma eyes under OHA use. All participants underwent corneal parameter assessment using SP-3000P (Topcon Corp., Tokyo, Japan) at the time of diagnosis and the final visit. The OHA dose and timing of use were recorded. The ocular hypotensive agents score (OHAS) was determined based on the number, formula, frequency, and duration of OHA use. Baseline data showed no significant differences between the two groups with and without OHA use. At the final visit, the OHA-treated group showed significantly lower corneal thickness and corneal endothelial cell density than those of the control group. A weak positive correlation between the OHAS and changes in corneal endothelial cell hexagonality was noted. However, no correlation was observed between the OHAS and changes in corneal thickness or endothelial cell density. In conclusion, patients with glaucoma and using OHAs should undergo the corneal structural properties examinations before donation to ensure the quality of donor cornea.

A comparison of rebound and applanation tonometry in children with and without primary congenital glaucoma

Background: Intraocular pressure (IOP) measurement should be accurate in a paediatric population with primary congenital glaucoma (PCG).Aim: This study aims to investigate the difference between the change in IOP measurements using rebound tonometry (RBT) and handheld applanation tonometry (AT) (Perkins applanation tonometer [PAT]) in patients with and without PCG.Setting: Johannesburg, South Africa.Methods: Measurements were taken under anaesthesia, using RBT and AT at 0 min, 5 min and 10 mins after induction and prior to intubation. Corneal pachymetry and corneal diameters were measured.Results: Sixty-five children were included, 19 with PCG and 46 without PCG. The mean age (standard deviation [s.d.]) was 3.2 (2.25) years and 4.8 (2.4) years, respectively. The overall mean difference in IOP between RBT and PAT across both PCG and non-PCG groups was found to be 4.92 mmHg (95% confidence interval [CI]: 2.80 – 7.03) p 0.001, with RBT having higher readings. This difference was greater in the PCG group, with the IOP difference of 9.05 mmHg (95% CI: 2.6 – 15.5) p = 0.004. Mean corneal pachymetry (s.d.) was 585.6 (81.48) µm in the PCG group and 518.31 (39.9) µm in the non-PCG group. Univariate analysis showed that IOP was significantly related to corneal pachymetry, with a 11 mmHg increase in IOP for every 100 μm change in corneal thickness for measurements done with RBT (p 0.001), compared to 4 mmHg using PAT (p = 0.008).Conclusion: Intraocular pressure measurements done with RBT in children with and without PCG were overestimated compared to PAT.Contribution: This difference was more pronounced in PCG patients. In addition, IOP was significantly related to corneal thickness.

Comparison of clinical outcomes between femtosecond laser-assisted cataract surgery versus conventional phacoemulsification in vitrectomized eyes - A prospective interventional study.

To compare the clinical outcomes and surgical safety between femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification cataract surgery (CPCS) in vitrectomized eyes. A prospective interventional comparative study was conducted at a tertiary eye care center. Sixty consecutive cases requiring cataract surgery following pars plana vitrectomy were allocated into Group 1 ( n = 30), who underwent FLACS with intraocular lens implantation, and Group 2 ( n = 30), who underwent CPCS with intraocular lens implantation, and followed up for 3 months. Primary outcome measures were intraoperative ultrasonic cumulative dissipated energy (CDE) and intraoperative and postoperative complications. The secondary outcome measures were postoperative changes in endothelial cell count (ECC) and central corneal thickness (CCT). Baseline corrected distance visual acuity (CDVA), ECC, and CCT were comparable. Intraoperative CDE was significantly less in the FLACS group (8.11 vs. 15.83 percentage seconds; P = 0.012) with no intraoperative complication in either group. The postoperative CDVA was comparable between the groups with a trend toward earlier visual recovery in the FLACS group. The postoperative day (POD) 1 endothelial cell loss was higher in the CPCS group (7.54% vs. 2.05%), with the mean endothelial cell density being significantly higher in the FLACS group throughout the follow-up period ( P < 0.05). POD-1 corneal edema was higher in the CPCS group compared to FLACS with no significant difference on follow-up. Intraoperative migration of silicone oil to the anterior chamber was observed in 40% versus 0% in the CPCS versus FLACS groups, respectively. FLACS can be safely performed in post-vitrectomy eyes with lesser intraoperative ultrasonic energy used, postoperative endothelial cell loss, and change in CCT compared to CPCS.

Prospective randomized clinical trial evaluating efficacy and safety of a new ophthalmic viscosurgical device in patients undergoing cataract surgery.

To evaluate the efficacy and safety of Bio-Hyalur LVD compared with Viscoat ophthalmic viscosurgical device (OVD) in patients undergoing routine cataract surgery. 2 tertiary eyecare hospitals in Italy. Prospective randomized clinical trial. This study compared the outcomes of Bio-Hyalur LVD vs Viscoat OVD in patients undergoing standard cataract surgery with phacoemulsification and intraocular lens implantation from January 2021 to April 2022. The primary outcome was mean change in IOP at 6 hours. Secondary outcomes included 1-day, 7-day, 30-day, and 90-day mean intraocular pressure (IOP); 7-day, 30-day, and 90-day corrected distance visual acuity; endothelial cell density (ECD); change in central corneal thickness (CCT); and complications including intraocular inflammation. 84 eyes of 84 patients (n = 41 in the Bio-Hyalur LVD group and n = 43 in the Viscoat group) were screened, enrolled, randomized, and included in the analysis. Mean change in IOP was significantly higher in the Viscoat group than in the Bio-Hyalur LVD group 6 hours ( P = .034), 7 days ( P < .001), 30 days ( P < .001), and 90 days ( P = .003) postoperatively. Mean change in uncorrected distance visual acuity and corrected distance visual acuity was significantly higher in the Bio-Hyalur LVD group 30 and 90 days postoperatively. No significant differences in ECD, CCT, and complication rates were observed between groups at any timepoint. Bio-Hyalur LVD OVD was safe and effective in patients undergoing routine cataract surgery. Bio-Hyalur LVD OVD did not confer a higher risk of postoperative increase in IOP.

Acute alcohol consumption modulates corneal biomechanical properties as revealed by optical coherence elastography

Acute alcohol ingestion has been found to impact visual functions, including eye movement, but its effects on corneal biomechanical properties remain unclear. This study aimed to investigate the influence of acute alcohol consumption on corneal biomechanical properties using optical coherence elastography (OCE). An air-coupled ultrasound transducer induced elastic waves in mice corneas in vivo, and a high-resolution phase-sensitive optical coherence tomography (OCT) system tracked the mechanical waves to quantify the elastic wave speed. In vivo measurements were performed on three groups of age- and gender-matched mice: control, placebo (administered saline), and alcohol (administered ethanol) groups. Longitudinal measurements were conducted over a one-hour period to assess acute temporal changes in wave speeds, which are associated with inherent biomechanical properties of the cornea. The results showed a significant decrease in wave speed for the alcohol group after 10 min of ingestion in comparison to pre-ingestion values (p = 0.0096), whereas the temporal wave speed changes for the placebo group were statistically insignificant (p = 0.076). In contrast, the control group showed no significant changes in elastic wave speed and corneal thickness. Furthermore, a significant difference was observed between the wave speeds of the placebo and alcohol groups at each measurement time point between 10 and 50 min (p < 0.05), though both groups exhibited a similar trend in corneal thickness change. The findings of this study have important implications for clinical assessments and research in corneal disorders, highlighting the potential of OCE as a valuable tool for evaluating such changes.

Intraoperative Performance and Early Postoperative Outcomes Following Phacoemulsification With Three Fluidic Systems: A Randomized Trial.

To compare intraoperative performance and early postoperative outcomes following phacoemulsification with two systems using active fluidics and one using gravity-based fluidics. In this prospective randomized trial, 200 eyes were randomized to the traditional and Active Sentry groups (n = 80 eyes each) where the Centurion Vision System was used with traditional or Active Sentry (Alcon Laboratories, Inc) hand-pieces, respectively, or the Infinit group (n = 40 eyes) where the Infiniti Vision System (Alcon Laboratories, Inc) was used. Within the traditional and Active Sentry groups, there were two subgroups with low (30 mm Hg) or high (55 mm Hg) intraocular pressure (IOP) used. Outcome measures compared were: cumulative dissipated energy (CDE), percentage change in central corneal thickness (CCT) at 1 day, 1 week, and 1 month, anterior chamber cells at 1 day and 1 week, rate of rise and fall of IOP following occlusion break, corneal endothelial cell density (ECD), and macular thickness 6 months postoperatively. CDE was significantly lower in group II compared to the traditional group (2.96 ± 1.4 vs 4.14 ± 2.2, P = .001). With 30 mm Hg IOP, the Active Sentry group had significantly less percentage change in CCT at 1 week postoperatively compared to the traditional handpiece group (0.01% vs 0.02%, P = .008). Incidence of anterior chamber cells less than grade 2 on day 1 was significantly higher in the Active Sentry group (82.9% vs 52%, P = .03). Percentage change in ECD was significantly lower in the Active Sentry group (-0.957 vs -0.98%, P = .005). Significantly faster rise of IOP to baseline following occlusion break was seen in the Active Sentry group. The use of Active Sentry handpiece was associated with lower CDE, less postoperative increase in CCT, fewer anterior chamber cells, and faster rise of IOP following occlusion break. [J Refract Surg. 2024;40(5):e304-e312.].

Corneal Endothelial Cells and Central Corneal Thickness in Pseudoexfoliation Patients

Objective: Investigating the impact of pseudoexfoliation syndrome on changes occurring in corneal endothelial cells and central corneal thickness, while assessing the influence of the degree of pseudoexfoliation on endothelial cell changes. Methods: In this analytic case-control study (Cross Sectional), the research sample included 60 patients (120 eyes) from the ophthalmic clinic attendees at Tishreen University Hospital in Latakia during the period 2023-2024. Results: The average corneal endothelial cell count was lower in the pseudoexfoliation group (2218.91±311.5 cells/mm²) compared to the control group (2559.82±290.7 cells/mm²) with a (p-value of 0.0001). The average percentage of hexagonal cells was lower in the pseudoexfoliation group (48.55±14.9 %) compared to the control group (62.32±9.7%) with a (p-value of 0.0001). No statistically significant differences were observed between the research groups in terms of average cell volume change coefficient with a (p-value of 0.9). The average cell area was higher in the pseudoexfoliation group (487.92±71.3 µm²) compared to the control group (419.94±72.2 µm²) with a (p-value of 0.003). The average central corneal thickness was lower in the pseudoexfoliation group (515.93±41.9 µm) compared to the control group (544.22±26.6 µm) with a (p-value of 0.04). We observed increased changes in corneal endothelial cells and central corneal thickness with an increase in the degree of pseudoexfoliation. Conclusion: Corneal endothelial cells and central corneal thickness are affected in patients with pseudoexfoliation syndrome, and these changes increase with severity of pseudoexfoliation.

In vivo assessment of human corneal epithelial cells in orthokeratology lens wearers: A pilot study.

Central corneal epithelial thinning associated with midperipheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet, the cellular mechanism governing the regional change in refractive power remains elusive. This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers. A new human prototype of a polarization-dependent optical coherence microscope was developed to enable noncontact and noninvasive in vivo imaging of corneal epithelial cells in ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and midperipheral corneal locations in four ortho-k wearers and four spectacle wearers serving as controls. Polarization-dependent optical coherence microscope achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view of 0.5 × 0.5 mm2 with an isotropic resolution of ~2.2 mm. The central epithelial thinning and midperipheral epithelial thickening were consistent across all ortho-k wearers. However, the inconsistency in their regional epithelial cell density highlighted a great variability in individual response to ortho-k treatment. There was no strong correlation between epithelial thickness and cell density, especially at the midperipheral cornea, in ortho-k participants. This study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cells before and during ortho-k treatment to identify factors governing individual response to ortho-k treatment and ultimately inform the dynamics of epithelial cells taking place during the ortho-k treatment.

A New Biomechanical Deformation Response Parameter: Change in Central Corneal Thickness During Air Puff Induced Corneal Deformation

Purpose To investigate the percent change in central corneal thickness (%ΔCCT) during air-puff-induced deformation as an indicator of corneal biomechanical response. Methods Forty ex vivo human eyes from forty donors were imaged using the CorVis ST at experimentally controlled intraocular pressure (IOP) of 10, 20, 30, and 40 mmHg, followed by uniaxial strip testing to calculate tensile modulus. The CorVis ST research software tracked the anterior and posterior cornea edges and determined the dynamic corneal response (DCR) parameters. Eyes were excluded if image quality or posterior tracking issues were present. Custom algorithms were used to calculate CCT during deformation using a ray-tracing method to correct for Scheimpflug and optical distortion within each image. Correlation and stepwise regression analyses between the shape-related DCR parameters and %ΔCCT were conducted. A mixed model analysis was performed to test the effect of IOP and the strongest significant predictors of the stepwise regression on %ΔCCT. The significance threshold was set to p < 0.05. Results Thirty eyes were ultimately analyzed and CCT increased significantly from the pre-deformation state to the highest concavity state at each IOP level (p < 0.001). IOP and multiple shape DCRs were found to be significantly related to %ΔCCT (p < 0.0001). The strongest predictor of %ΔCCT was integrated inverse radius (IIR) (p < 0.0001; partial R2 = 0.4772) with no other parameter having a partial R2 value greater than 0.04. The mixed model analysis showed that IIR was the sole predictor (p = 0.0098) and IOP was no longer significant as a single predictor. However, the interaction of IIR with IOP (p = 0.0023) had a significant effect on %ΔCCT. Conclusion Percent change in CCT is influenced by corneal stiffness as indicated by the significant relationship with IIR. The %ΔCCT may be a potential biomarker for determining differences in corneal deformation response with corneal diseases.