Lower Central Corneal Thickness Research Articles

Association of digital eye strain with central corneal thickness: a cross-sectional observational pilot study.

This study aimed to evaluate whether the digital eye strain (DES) was associated with the low central corneal thickness (CCT). This observational cross-sectional pilot study was conducted from April 2023 to October 2023 at a tertiary eye care centre in North India, where CCT values were compared between subjects with DES and those without DES. Two hundred and eighty subjects (n = 280) aged 15-40years with clear corneas and lenses were initially included in this study. Those with corneal opacity, corneal degeneration, pregnancy, and diabetes were excluded. These subjects were then assessed with a 'computer vision syndrome questionnaire (CVS-Q)' test. Participants having a score ≥ 6 were grouped as the "DES group" and participants having a score < 6 were grouped as the "Control group". The participants from each group were then examined with Spectral Domain Ocular Coherence Tomography (SD-OCT) to measure CCT. The primary outcome was to evaluate the comparative difference in CCT values between the two groups as well as the association of DES with CCT values. The study included one hundred and forty (n = 140) subjects each in the DES group and the control group. The DES score assessed with the CVS-Q questionnaire ranged from 6 to 32 in the DES group, with a mean ± SD of 17.08 ± 7.01. The overall mean CCT was 507.31 ± 31.01 (median, 512 microns; range, 450-601 microns). There was a significant difference in the mean CCT between the two groups, with lower mean CCT values in the DES group (487.76 ± 23.61 microns) than the control group (526.87 ± 24.53 microns) (p < 0.0001). The CVS-Q test score had moderate inverse correlation in the DES group (Pearson's r = - 0.42, p < 0.01) and negligible correlation (Pearson's r = - 0.14, p = 0.12) in the control group with CCT. Central corneal thickness was observed to be reduced among the subjects with digital eye strain (DES).

Investigation of corneal topographic and ocular surface parameters in ocular rosacea based on skin subtypes.

To compare the corneal topographic parameters and ocular surface parameters of ocular rosacea (OR) patients across skin subtypes of the disease and healthy controls. This prospective study included 180 eyes of 90 OR patients and 60 eyes of 30 healthy controls. Among the OR patients, 30 had phymatous (60 eyes), 30 had erythematotelangiectatic (60 eyes) and 30 had papulopustular skin types (60 eyes). We measured the mean keratometry (Kmean), maximum keratometry (Kmax), thinnest corneal thickness (TCT), central corneal thickness (CCT) and corneal volume (CV) with a topography device (Sirius, Italy). Additionally, we measured tear-film breakup time (TBUT), Meiboscore and Schirmer's test from all participants. We compared parameters across OR skin groups as well as with controls. Kmean and Kmax were significantly steeper in the OR group compared to controls (p<0.05). We found significant correlations between "Kmean-Kmax", "CV-TCT", "CV-CCT", and "TCT-CCT" in both groups, while significant correlations between "age-Kmean", "age-Kmax", and "Meiboscore-Kmax" were present only in OR patients. When patients were divided into subgroups according to their skin subtypes, the papulopustular and phymatous subgroups had steeper Kmean and Kmax compared to the erythematotelangiectatic and control groups (P<0.05). The papulopustular subgroup had lower CCT, lower TBUT and higher Meiboscore compared to the phymatous, erythematotelangiectatic and control groups but lower TCT compared to controls (P<0.05). In addition, there were significant correlations between "Kmax-CV", "Kmax-TCT", and "Kmax-meiboscore" only in the papulopustular subgroup (P<0.05). It appears that the corneas of OR patients are steeper than those of healthy controls; corneal thinning and abnormalities of ocular surface parameters are more pronounced in papulopustular skin types.

Excimer Laser-Assisted Deep Anterior Lamellar Keratoplasty Versus Penetrating Keratoplasty for Patients With Keratoconus: A Retrospective Analysis From the Homburg Keratoconus Center.

To evaluate the outcome of excimer laser-assisted deep anterior lamellar keratoplasty (Exc-DALK) and penetrating keratoplasty (Exc-PKP) for keratoconus (KC). We included 123 eyes and compared the outcome of 30 eyes undergoing big-bubble Exc-DALK after stromal debulking (G1) against a matched group of 83 eyes undergoing Exc-PKP (G2) in our department. G2 was created after performing a pseudorandom stratified bootstrapping of our PKP database starting with 2802 surgeries with removal of any bias. Main outcomes included best corrected visual acuity (BCVA), spherical equivalent (SE), tomographic changes, and endothelial cell density (ECD). Data were compared preoperatively, postoperatively with 2 double-running cross-stitch sutures according to Hoffmann [2 and 10 months postoperatively (T1 and T2)], after first suture removal [15 months postoperatively (T3)], and after final suture removal [26 months postoperatively (T4)]. Preoperatively, all parameters were comparable without significant differences. At T1, G1 showed significantly better BCVA (P = 0.01), lower SE (P = 0.04), lower anterior and posterior topographic astigmatism (ATA and PTA, P < 0.01), lower maximal keratometry (P = 0.02), and lower central corneal thickness (P < 0.01). At T2, G1 showed significantly better BCVA (P = 0.04), lower PTA (P < 0.01), and higher ECD (P < 0.01). At T3, G1 showed significantly lower ATA (P = 0.01) and PTA (P < 0.01) and higher ECD (P = 0.02). At T4, G1 showed significantly lower PTA and higher ECD (P < 0.01) but no significant difference in BCVA (P = 0.07). Exc-DALK provided faster visual rehabilitation and represented an endothelial cell-sparing method compared with Exc-PKP. After final suture removal, Exc-DALK showed noninferior outcomes compared with Exc-PKP if the graft was placed on naked Descemet membrane.

The Risk Factors for Myopia Undercorrection in Second-Generation (Visumax 800) Keratorefractive Lenticule Extraction Surgery: A Retrospective Case-Control Study.

In this study, we aim to evaluate the risk factors of myopia undercorrection in recipients of second-generation keratorefractive lenticule extraction (KLEx) surgery. A retrospective case-control study was performed, and patients who received second-generation KLEx surgery were enrolled. The cases with myopia undercorrection were matched to non-myopia undercorrection cases with a 1:4 ratio according to age, and a total of 22 and 88 eyes were categorized into the undercorrection and control groups, respectively. Demographic, refractive, topographic, and surgical data were collected preoperatively. A generalized linear model was operated to evaluate the potential risk factors for myopia undercorrection. The uncorrected distance visual acuity (UDVA) at three months postoperation was significantly better in the control group (p = 0.006), and residual myopia and SE were significantly higher in the undercorrection group during the whole follow-up period (all p < 0.001). The UDVA value showed a trend of improvement in the control group (p < 0.001), and the changes to SE and residual myopia were significantly lower in the control group (both p < 0.001). Regarding the risk factors for myopia undercorrection in the whole population and the high-myopia population, a higher manifest sphere power, higher steep keratometry (K), higher topographic cylinder, lower central corneal thickness (CCT) at apex, higher CCT difference and lower residual stromal thickness (RST) correlated to myopia undercorrection (all p < 0.05). In the low-myopia population, only higher myopia and lower RST correlated to myopia undercorrection (both p < 0.05). In conclusion, a high-sphere power and irregular topographic pattern correlated to myopia undercorrection after the second KLEx surgery, especially for individuals with high myopia.

Identifying Factors Associated With Fast Visual Field Progression in Patients With Ocular Hypertension Based on Unsupervised Machine Learning.

We developed unsupervised machine learning models to identify different subtypes of patients with ocular hypertension in terms of visual field (VF) progression and discovered 4 subtypes with different trends of VF worsening. We then identified factors associated with fast VF progression. To identify ocular hypertension (OHT) subtypes with different trends of visual field (VF) progression based on unsupervised machine learning and to discover factors associated with fast VF progression. Cross-sectional and longitudinal study. A total of 3133 eyes of 1568 ocular hypertension treatment study (OHTS) participants with at least 5 follow-up VF tests were included in the study. We used a latent class mixed model (LCMM) to identify OHT subtypes using standard automated perimetry (SAP) mean deviation (MD) trajectories. We characterized the subtypes based on demographic, clinical, ocular, and VF factors at the baseline. We then identified factors driving fast VF progression using generalized estimating equation (GEE) and justified findings qualitatively and quantitatively. Rates of SAP mean deviation (MD) change. The LCMM model discovered four clusters (subtypes) of eyes with different trajectories of MD worsening. The number of eyes in clusters were 794 (25%), 1675 (54%), 531 (17%), and 133 (4%). We labeled the clusters as improvers (cluster 1), stables (cluster 2), slow progressors (cluster 3), and fast progressors (cluster 4) based on their mean of MD decline rate, which were 0.08, -0.06, -0.21, and -0.45dB/year, respectively. Eyes with fast VF progression had higher baseline age, intraocular pressure (IOP), pattern standard deviation (PSD) and refractive error (RE), but lower central corneal thickness (CCT). Fast progression was associated with being male, heart disease history, diabetes history, African American race, and stroke history. Unsupervised clustering can objectively identify OHT subtypes including those with fast VF worsening without human expert intervention. Fast VF progression was associated with higher history of stroke, heart disease and diabetes. Fast progressors were more from African American race, males, and had higher incidence of glaucoma conversion. Subtyping can provide guidance for adjusting treatment plans to slow vision loss and improve quality of life of patients with a faster progression course.

Topographic and Surgical Risk Factors for Early Myopic Regression between Small Incision Lenticule Extraction and Laser In Situ Keratomileusis.

Our objective was to evaluate the topographic and surgical factors of early myopic regression between laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE). A retrospective case-control study was conducted, and 368 and 92 eyes were enrolled in the LASIK and SMILE groups via propensity score matching (PSM). Visual acuity, refractive status, axial length, and topographic/surgical parameters were collected. Multiple linear regression was applied to the yield coefficient and the 95% confidence interval (CI) of the parameters. The cumulative incidence of early myopic regression was higher in the LASIK group (p < 0.001). In the SMILE group, a lower central corneal thickness (CCT) thinnest value and a higher corneal cylinder associated with early myopic regression were observed; meanwhile, in the LASIK group, a lower CCT thinnest value, a higher steep corneal curvature, a larger optic zone, and a lower flap thickness related to early myopic regression were observed (all p < 0.05). In the SMILE group, a higher CCT difference correlated with early myopic regression was observed compared to the LASIK group (p = 0.030), and higher steep corneal curvature and lower cap/flap thickness (both p < 0.05) correlated with early myopic regression were observed in the LASIK group compared to the SMILE group. In conclusion, CCT differences significantly influence early myopic regression in the SMILE group; meanwhile, corneal curvature and flap thickness affect early myopic regression principally in the LASIK group.

Central corneal thickness in new cases of dry eyes: A case-control study

Significance Loss of homeostasis and chronic inflammation result in ocular surface damage in dry eyes, which is also associated with corneal thinning in established cases. Yet, the correlation between corneal thickness and new cases of dry eyes remains inadequately supported by evidence. Purpose This study aimed to compare the central corneal thickness of new cases of dry eyes to that of age- and gender-matched controls. Methods A total of 45 dry eye patients were compared with 61 age- and gender-matched non–dry eye individuals. The Ocular Surface Disease Index (OSDI) questionnaire was used to evaluate symptoms, and the central corneal thickness was measured with a Nidek CEM-530 specular microscope. Patients were grouped based on disease severity (OSDI scores), and the clinical findings were compared between groups for slit-lamp examinations, Schirmer's I test, and tear film breakup time. Results The median age of patients was 25.0 (interquartile range [IQR], 20.0 to 32.0) and 27.0 (IQR, 20.0 to 32.0) years in the control and dry eye groups, respectively (p=0.63). The median (IQR) values of the OSDI scores, tear film breakup time scores, and Schirmer's test measurements in the control groups were 10.4 (8.3 to 10.4), 12.0 (11.0 to 14.0) seconds, and 16.0 (13.5 to 19.5) mm, respectively, which differed from the dry eye groups (p&lt;0.0001). These values in the dry eye group were 29.1 (25.0 to 39.5), 4.0 (3.0 to 8.0) seconds, and 8.0 (3.5 to 11.0) mm, respectively. Patients with dry eyes had lower central corneal thickness than controls (p&lt;0.01). The mean ± standard deviation central corneal thicknesses in patients with dry eyes and the control group were 520.3 ± 26.8 and 545.3 ± 18.8 μm, respectively. Conclusions The central corneal thickness in dry eyes was significantly reduced compared with the control group. These findings may be useful in monitoring and managing dry eyes and should be considered in intraocular pressure measurements and refractive surgical procedures.

Altered Corneal Biomechanics According to the Biomechanical E-Staging in Pellucid Marginal Degeneration

Purpose: The purpose of this study was to investigate corneal biomechanics in pellucid marginal degeneration (PMD) compared with healthy controls using Corvis ST (Oculus, Germany) by using the new biomechanical E-staging (based on the Corvis Biomechanical Factor, the linearized Corvis Biomechanical Index) together with tomographic parameters. Methods: Corneal biomechanical and topographic data of 75 eyes of 75 patients with PMD and 75 eyes of 75 age-matched and sex-matched healthy controls were investigated. Topographic parameters (K1, K2, Kmax, central corneal thickness (CCT), and Belin/Ambrósio Deviation Index (BAD-D) were evaluated in dependence of and correlated with the biomechanically defined E-stages. Biomechanical parameters were also recorded for the 2 groups. Results: Patients with PMD showed higher K2, Kmax, BAD-D, and Corvis Biomechanical Factor values and a lower CCT compared with healthy controls (P &lt; 0.001). The E-stage was positively correlated with K1, K2, Kmax, BAD-D, and intraocular pressure difference and negatively correlated with CCT. Stage-dependent analysis revealed a significant increase in K1, K2, Kmax (P &lt; 0.001), and BAD-D (P = 0.041) in stage E3 compared with E0 and a significant decrease in stage E2 in CCT (P = 0.009) compared with E0. Conclusions: This study showed that patients with PMD may have a reduced corneal stiffness compared with healthy controls which worsens with increasing E-stage. Significant changes in topographic parameters were observed at stage E2 for CCT and at stage E3 for K1, K2, Kmax, and BAD-D when compared with stage E0.

Longitudinal evaluation of advanced glaucoma: ten year follow-up cohort study

This study focused on patients with advanced open-angle glaucoma (OAG) and aimed to identify key factors for monitoring them. We included 127 such patients who were followed for seven years or more, undergoing annual ophthalmic examinations. Glaucoma progression was defined as a deterioration in either structure or function. The progression rates and risk factors were evaluated. The patients were divided into upper- and lower-half subgroups based on the reduction in intraocular pressure (IOP) from the baseline. Over an 11-year period, glaucoma progression was detected in 59 eyes (46.5%). The rate of change in mean deviation (MD) was − 0.43 dB/year for the entire population; − 0.67 dB/year for progressors; and − 0.20 dB/year for non-progressors. Hypertension and disc hemorrhage (DH) were more common in progressors compared to non-progressors (45.8 vs. 23.5%, 11.9 vs. 1.5%; P = 0.008 and P = 0.016). Multivariate Cox’s proportional hazard model revealed that the presence of DH and a better baseline MD were associated with glaucoma progression. Additionally, patients with a higher percentage reduction in IOP (> 20.94%) had a lower risk of progression compared to those with less reduction. Inadequate IOP reduction, better baseline MD, presence of DH, and lower central corneal thickness were identified as risk factors for progression in advanced OAG patients.

The Effect of β-Blocker Eye Drops on Pulse Rate, Ocular Blood Flow, and Glaucoma Progression: A Retrospective Longitudinal Study.

Our study was conducted to determine factors associated with the effectiveness of a β-blocker eye drop add-on in altering pulse rate (PR) in glaucoma patients. This retrospective study examined 236 eyes of 138 patients who received a β-blocker eye drop add-on during follow-up. Patients were included if at least one PR measurement was available both before and after the add-on was started. We collected data on ophthalmic parameters: longitudinal PR; longitudinal choroidal blood flow, represented by laser speckle flowgraphy-measured mean blur rate (MBR); and diacron-reactive oxygen metabolites (d-ROMs). We used a multivariable linear mixed-effects model to investigate the effectiveness of the β-blocker eye drop add-on in altering PR and examined factors contributing to a larger PR alteration after the add-on was started by analyzing the effect on PR of the interaction term between the add-on and clinical factors. We used the k-means method to classify the patients. The β-blocker eye drop add-on reduced PR (- 7.61bpm, P < 0.001). Female gender, higher PR when the add-on was started, lower central corneal thickness, and a higher d-ROM level were associated with greater reduction in PR (P < 0.05). In a cluster of patients with these clinical features, choroidal MBR increased by + 3.42% when we adjusted for change over time; MD slope, which represents the speed of glaucoma progression, improved by + 0.64dB/year (P < 0.05). We identified a glaucoma subgroup in which PR decreased, choroidal blood flow increased, and glaucoma progression slowed after a β-blocker eye drop add-on was started.

Ocular Dominance and Its Association With Central Corneal Thickness: An Observational Study in Central India.

Background The aim of this study is to determine ocular dominance and its association with central corneal thickness (CCT). These two parameters are of great significance in clinical practice; identifying the dominant eyehelpsin planning cataract surgeries, treatment of presbyopia, monovision correction, etc., and assessing the CCT helps inearly diagnosis and management of keratoconus, glaucoma, contact lens-related complications, and dry eye. Methods A cross-sectional study that involvespatients and volunteers who have come for a checkup to the ophthalmology department of the college hospital. Ninety patients were examined for this study within two months. The hole-in-card test is performed to determine the ocular dominance in people with normal and healthy eyes without any pathologies except refractive errors. Specular microscopy through a non-contact modality will be done to assess thethickness of the central cornea in both eyes. Statistical analysis was done using the paired t-test to compare the patient's eyes and the chi-square test, which helps usassociate ocular dominance and CCT. Results Right eye dominance was seen in the majority of the participants (72.91%), whereas left eye dominance was seen in comparatively fewer participants (27.08%). The CCT of the dominant eye is found to be 520.40± 29.83μm and that of the non-dominant eye is 524.40± 29.37μm. A lower CCT in the dominant eye was seen in 83.33% of the subjects; 14.58% of them had a higher CCT in the dominant eye and 2.08% had the same CCT in both eyes. Conclusion From the observational study that has been made, the majority of the population shows right eye dominance. The CCT is relatively thinner in the dominant eye. About 80-85%of the examined people showed a thinner cornea in the dominant eye. But we cannot generalize that the eye with a lessercorneal thickness will be the dominant eye in all the cases, as a few cases have shown dominance in the eye with a thicker cornea.

Correlation between retinal nerve fiber layer thickness and anterior segment parameters in patients with pseudoexfoliation: A cross-sectional comparative study.

The purpose of this study was to assess the retinal nerve fiber layer (RNFL) thickness in patients with pseudoexfoliation (PXF) and to correlate it with anterior segment parameters such as intraocular pressure (IOP), central corneal thickness (CCT), pigments in angle structures, and grades of PXF. This was a cross-sectional comparative study in a tertiary care center. Patients having unilateral PXF were categorized as group 1. Age- and sex-matched healthy controls were categorized as group 2. All subjects underwent IOP measurement, CCT measurement, and retinal nerve fiber thickness measurement. Subjects in group 1 also underwent gonioscopy and perimetry. Data were entered and analyzed using the IBM-SPSS program (version 20.0); Chicago, IL. Mean RNFL thickness in group 1 was 85.91 ± 22.237 μ and in group 2 was 106.65 ± 6.1 μ. The mean RNFL thickness in patients with PXF syndrome was 103.38 ± 5.815 μ and in patients with PXF glaucoma was 67.82 ± 17.984 μ. The mean CCT in patients with PXF syndrome was 516.41 ± 23.03 μ and in patients with PXF glaucoma was 507 ± 33.05 μ and control group was 526.6 m. The mean IOP in patients with PXF syndrome was 8 ± 6.01 mmHg; in patients with PXF glaucoma was 17.21 ± 7.33 mmHg; and in the control group was 14.12 ± 2.693 mmHg. There was a negative correlation between IOP and RNFL thickness, and a positive correlation between CCT and RNFL thickness, but it was not statistically significant. A statistically significant correlation was found between grades of PXF and RNFL thinning with a correlation coefficient of 0.437 (P = 0.001). Patients with PXF have a lower CCT, higher mean IOP, and RNFL thinning compared to normal subjects. The presence of grade 3 PXF (on the lens surface edge) showed a statistically significant correlation with RNFL thinning.

Comparison of Corneal Thickness Measurements After Customized Corneal Crosslinking Using High-Resolution Optical Coherence Tomography and Scheimpflug Tomography.

The aim of this study was to compare the evolution of corneal pachymetry after customized corneal crosslinking (CXL) between Scheimpflug-based and optical coherence-based corneal tomography (OCT). In this retrospective study, central corneal thickness (CCT), thinnest corneal thickness, and epithelial thickness of 33 eyes of 33 patients with keratoconus were measured preoperatively and 1, 3, and 12 months after customized CXL using the Pentacam HR and the MS-39. The mean pachymetry values of measurements were compared with a paired sample t test. Bland-Altman plots and 95% limits of agreement (LoA) were used to assess the agreement between the measurements of the 2 devices. The mean age of the participants was 29.7 ± 11.4 years. At baseline, the mean CCT measurements were equal with Pentacam HR (478.30 ± 36.77 μm) and MS-39 (478.46 ± 38.01 μm). After CXL, CCT obtained by Pentacam HR was 460.65 ± 38.69 μm, 464.65 ± 44.45 μm, and 476.77 ± 39.85 μm, and by MS-39 was 478.18 ± 39.50 μm, 472.89 ± 40.92 μm, and 479.51 ± 39.20 μm at 1, 3, and 12 months, respectively. Pentacam HR measured significantly lower CCT ( P < 0.05) at months 1 and 3 after CXL. The agreement was smallest between both devices at month 1 (95% LoA -59 to 24 μm) followed by month 3 (95% LoA: -41 to 23 μm). Epithelial thickness, measured with OCT alone, increased significantly at 1 month and regained preoperative levels at 3 months and thereafter. After CXL, corneal pachymetry significantly differs between OCT-based and Scheimpflug-based corneal tomography. Pentacam HR seems to underestimate pachymetry when haze is present.

Corneal biomechanical properties in vernal keratoconjunctivitis and its subtypes: a preliminary study.

To explore the corneal biomechanical properties (CBPs) of patients with vernal keratoconjunctivitis (VKC) and the discrepancies among three subtypes of VKC including palpebral, limbal, and mixed forms. Forty eyes of 20 VKC patients and twenty eyes of ten non-VKC patients were included in this case-control study. Patients with VKC were further divided into three subtypes (six patients in Palpebral form, five patients in limbal form, and nine patients in mixed form). The CBPs of all patients were obtained from the Corneal Visualization Scheimpflug Technology (Corvis ST). First applanation (A1) length, Ambrosio relational thickness in horizontal (ARTh), and stiffness parameter at first applanation (SP-A1) were significantly lower in the VKC group while A1 velocity was significantly higher in the VKC group (p < 0.05), compared to the non-VKC group. Furthermore, A1 velocity presented a positive correlation with disease course (p < 0.05). In addition, VKC patients of limbal form had lower central corneal thickness (CCT), SP-A1, and higher deformation amplitude ratio (DA ratio), compared to the other two subtypes (p < 0.05). Besides, patients in limbal form had higher A1 velocity, integrated radius, and corneal biomechanical index (CBI) compared with mixed form, and lower A1 length than palpebral form (p < 0.05). The corneas of VKC patients were softer and more protruded compared with the control group, and the property of steepness was closely related to disease course. VKC patients in limbal form were more inclined to be keratoconus than the other two subtypes due to their CBPs` discrepancies.

Comparison of Central Corneal Thickness Measurements with Four Different New Devices and Ultrasound Pachymetry

To assess the central corneal thickness (CCT) with 5 different devices, evaluate the repeatability of the devices, and determine the possible relationship between thickness values and sex. The study included 308 eyes of 154 patients (76 women, 78 men) between the ages of 18-30 who presented to the Ophthalmology Clinic of Muğla Sıtkı Koçman University Training and Research Hospital. Autorefractor (Topcon, Japan), ultrasound pachymetry (UP) (Ceniscan, USA), high-resolution Pentacam (Oculus, USA), anterior segment-optical coherence tomography (AS-OCT) (Optovue, USA), and Spectralis AS-OCT (Heidelberg, Germany) measurements were assessed. The mean age of the study participants was 23.2±0.2 years and the mean CCT was 540±14.1 μm, with no statistically significant difference in CCT between sexes (p&gt;0.05). Mean CCT values were 557.0±26.7 μm with the autorefractor, 543.6±32.9 μm with UP, 533.8±30.2 μm with the Oculus Pentacam, 519.8±30.1 μm with Optovue AS-OCT, and 547.5±31.6 μm with Heidelberg AS-OCT. Pairwise comparisons between devices showed that the Optovue AS-OCT gave significantly lower CCT measurements than the autorefractor and Heidelberg AS-OCT device (p=0.027 and p=0.033, respectively). The coefficient of repeatability for autorefractor, UP, high-resolution Pentacam, Optovue AS-OCT, and Heidelberg AS-OCT CCT measurements were 1.51%, 2.46%, 3.72%, 2.57%, and 3.34%, respectively. Measurements made with five different devices showed that CCT was comparable and clinically usable. However, it was determined that the Optovue AS-OCT showed lower CCT values compare to other devices. When compared in terms of repeatability, it was found to be lower in the Pentacam than other devices.

Effect of mitomycin-C on corneal endothelial cell parameters after refractive surface ablation procedures.

The effect of mitomycin-C (MMC) on the reduction of endothelial cell count in the cornea remains controversial. We aimed to evaluate the effect of MMC on corneal endothelial cell parameters after refractive surface ablation procedures, including photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK). In this interventional, comparative, follow-up study, 342 eyes of 171 patients were followed up for 6 months. Patients undergoing PRK or LASEK were included and were divided into two groups: group one (188 eyes of 94 patients) with an ablation depth of ≥ 65 µm and who received intraoperative 0.02% MMC for 30 s, and group two (154 eyes of 77 patients) with an ablation depth of < 65 µm and who received balanced salt solution for 30 s. Changes in endothelial cell density (ECD), central corneal thickness (CCT), coefficient of variation (CV), and hexagonality values were compared between the groups at 3 and 6 months after surgery. The mean (standard deviaiton [SD]) age of the patients was 28.11 (6.56) years. The mean (SD) ECD did not change significantly in either group between the baseline and at 3 and 6 months postoperatively. The baseline mean ECD was significantly higher in group one than that in group two (P < 0.001) and remained so at 3 (P = 0.002) and 6 months (P = 0.022) postoperatively. The baseline hexagonality value was lower in group one (P = 0.173), with a gradual decrease during the postoperative follow-up as compared with that in group two (P = 0.016 and 0.001 at 3 and 6 months postoperatively, respectively). Group one had a significantly lower CCT at 3 and 6 months postoperatively (both P < 0.001) and a higher mean CV (3 months: P = 0.028; 6 months: P = 0.328). A single intraoperative application of MMC for 30 s as prophylaxis for corneal haze development during refractive surface ablation procedures had no significant effect on ECD up to 6 months postoperatively. Future studies with a contralateral-eye design (to neutralize factors specific to the individual patient), a larger sample size, and longer follow-up are necessary to confirm or disprove our observations.

Ocular Surface Disease Signs and Symptoms in Patients with Pseudoexfoliative Glaucoma: A Case-Control Study.

Purpose: The present study evaluates the differences in the prevalence of the signs and symptoms of ocular surface disease (OSD) in patients with PEX glaucoma (PEXG), compared to other glaucoma types (non-PEXG). Methods: Patients with non-PEXG and PEXG were prospectively examined for the presence and severity of OSD signs and questioned for symptoms using the OSDI (ocular surface disease index) questionnaire. Results: 116 patients were prospectively enrolled (58 non-PEXG and 58 PEXG). PEXG subjects who were older, had lower central corneal thickness (CCT) values, at a more advanced glaucoma stage and required more IOP lowering drops. OSD signs were prevalent in both groups: conjunctival hyperemia (74.5% non-PEXG vs. 94.8% PEXG), eyelid redness (70.7% vs. 96.6%), conjunctival (74.1% vs. 93.1%) and corneal fluorescein staining (81% vs. 93.1%) and abnormal TFBUT (82.8% vs. 87.9%). When adjusted for potential confounders, (older age, thinner CCT, more advanced glaucoma in PEXG) eyelid redness remained the only parameter significantly associated with PEXG, being 11 times more likely to occur in this group (p = 0.037). Conclusion: Subjects with PEXG presented a higher frequency of signs of OSD compared to other glaucoma types. When accounting for confounding factors, the only difference between the groups was the significantly higher presence (11 times more likely) of eyelid redness in PEXG, suggesting, in addition to glaucoma treatment, the impact of PEX on ocular surface integrity.

Surgical Management of Fuchs Endothelial Corneal Dystrophy: A Treatment Algorithm and Individual Patient Meta-Analysis of Descemet Stripping Only.

This study aims to determine predictive factors for success of Descemet stripping only (DSO) in Fuchs corneal endothelial dystrophy and propose a DSO treatment algorithm. Ovid MEDLINE, Embase, and Cochrane CENTRAL databases were searched to evaluate DSO case series, including combined phacoemulsification and DSO, and the use of Rho-kinase inhibitors (ROC-i). Our primary outcome was success of corneal clearance. Secondary outcomes included the time to corneal clearance, the postoperative endothelial cell count (ECC), and the impact of ROC-i. Sixty-eight cases were evaluated with a mean follow-up of 12.4 months. DSO corneal clearance was achieved in 85% (n = 58) with a mean time of 4.9 weeks for the ROC-i group compared with 10.1 weeks in the observation group (P < 0.0001). The mean central ECC postoperatively was higher in the ROC-i group compared with the observation group 1151 ± 245 versus 765 ± 169 cells/mm2, respectively (P < 0.018). The postoperative best-corrected visual acuity (BCVA) improved in 61 eyes (90%), with mean final BCVA of 0.17 (0.26) logMAR (P = 0.001), which was statistically significant compared with preoperative BCVA. Factors influencing success were 4-mm descemetorhexis size, a clear peripheral ECC with no clinical sequelae of decompensation or guttae, and a low central corneal thickness. No intraoperative complications were noted. The commonest postoperative complication was deep corneal stromal scars noted at the descemetorhexis edge (n = 9). DSO has a role in the treatment of a subset of patients with Fuchs corneal endothelial dystrophy and that adjuvant treatment with ROC-i may lead to faster corneal clearance.

Factors Associated With Differences in the Initial Location of Structural Progression in Normal-Tension Glaucoma.

Précis:Different clinical factors are associated with the location of the first structural progression in glaucoma.Purpose:The aim was to investigate the underlying clinical parameters affecting the location of the initial structural progression of glaucoma in patients with normal-tension glaucoma (NTG).Methods:This retrospective study included 228 eyes of 228 patients with NTG. In total, 130 eyes of 130 patients demonstrated structural progression (as determined by event-based guided progression analysis using Cirrus HD-optical coherence tomography) in the peripapillary retinal nerve fiber layer (ppRNFL) or macular ganglion cell inner plexiform layer (mGCIPL). Depending on where the progression occurred first, it was defined as either ppRNFL first progression or mGCIPL first progression. Clinical parameters associated with each first progression were identified using logistic regression.Results:In total, 50 eyes showed ppRNFL first progression and 64 eyes showed mGCIPL first progression. ppRNFL first progression was significantly associated with female sex [odds ratio (OR)=5.705, P=0.015], lack of systemic hypertension (OR=0.199, P=0.014), disc hemorrhage (OR=4.188, P=0.029), higher mean intraocular pressure (OR=1.300, P=0.03), and lower pattern SD (OR=0.784, P=0.028). In contrast, male sex (OR=0.450, P=0.043), lower central corneal thickness (OR=0.987, P=0.032), higher intraocular pressure fluctuation (OR=1.753, P=0.047), lower systolic blood pressure fluctuation (OR=0.839, P=0.002), and higher diastolic blood pressure fluctuation (OR=1.208, P=0.015) were significantly associated with mGCIPL first progression.Conclusions:Different clinical factors were associated with the initial site of structural glaucoma progression in patients with NTG depending on its peripapillary or macular location, and these findings suggest possible differences in underlying mechanisms of glaucoma damage.

Prediction model of free flaps in microkeratome-assisted LASIK

PurposeTo identify mechanical factors, as well as patients’ biometric and surgeons’ experience factors that correlate with the FF incidence in microkeratome (MK)-assisted LASIK and to construct a predictive model based on these parameters.Methods55,700 consecutive LASIK treatments of 28,506 patients between January 2017 and April 2020 done by 50 surgeons in 10 centers, all with Sub Bowman Keratome (SBK) and 90μ head (OUP) were analyzed retrospectively for the incidence of FF and their correlation to mean keratometry, central corneal thickness, MK ring height and stop, as well as surgeons’ experience. A prediction model was built and tested for sensitivity and specificity.ResultsThe incidence of FF using the SBK MK was 0.276%. Risk factors were low central corneal thickness, very flat (-1) or very thick (+2) ring height, and higher stop values (p<0.001). Mean keratometry and low surgeon experience were not correlated to FF incidence. A prediction model with a cut-off FF risk of 0.274%, a 76% specificity, and a 73% sensitivity was applied.ConclusionsFree flaps are rarely seen in modern MK LASIK. However, the incidence of this complication using the SBK MK increases using higher stop values, very thick and very thin MK rings, and in eyes with thin corneas.