Revealing regional variations in scleral shear modulus in a rabbit eye model using multi-directional ultrasound optical coherence elastography.

The mechanical properties of the sclera play a critical role in supporting the ocular structure and maintaining its shape. However, non-invasive measurements to quantify scleral biomechanics remain challenging. Recently introduced multi-directional optical coherence elastography (OCE) combined with an air-coupled ultrasound transducer for excitation of elastic surface waves was used to estimate phase speed and shear modulus in ex vivo rabbit globes (n = 7). The scleral phase speed (12.1 ± 3.2 m/s) was directional-dependent and higher than for corneal tissue (5.9 ± 1.4 m/s). In the tested locations, the sclera proved to be more anisotropic than the cornea by a factor of 11 in the maximum of modified planar anisotropy coefficient. The scleral shear moduli, estimated using a modified Rayleigh-Lamb wave model, showed significantly higher values in the circumferential direction (65.4 ± 31.9 kPa) than in meridional (22.5 ± 7.2 kPa); and in the anterior zone (27.3 ± 9.3 kPa) than in the posterior zone (17.8 ± 7.4 kPa). The multi-directional scanning approach allowed both quantification and radial mapping of estimated parameters within a single measurement. The results indicate that multi-directional OCE provides a valuable non-invasive assessment of scleral tissue properties that may be useful in the development of improved ocular models, the evaluation of potential myopia treatment strategies, and disease characterization and monitoring.

Misclassification of Eyes With Progressive Keratoconus Using the KISA% Index.

PURPOSE: To determine the misclassification rate of the keratoconus percentage (KISA%) index efficacy in eyes with progressive keratoconus. METHODS: This was a retrospective case-control study of consecutive patients with confirmed progressive keratoconus and a contemporaneous normal control group with 1.00 diopters or greater regular astigmatism. Scheimpflug imaging (Pentacam HR) was obtained for all patients. KISA% index and inferior-superior (IS) values were obtained from the Pentacam topometric/keratoconus staging map. Receiver operating characteristic curves were generated to determine the area under the receiver operating characteristic curve (AUROC), sensitivity, and specificity values. RESULTS: There were 160 eyes from 160 patients evaluated, including 80 eyes from 80 patients with progressive keratoconus and 80 eyes from 80 control patients. There were 20 eyes (25%) with progressive keratoconus misclassified by the KISA% index, with 16 eyes (20%) of the progressive keratoconus cohort classified as normal (ie, KISA% < 60). There were 4 eyes (5%) with progressive keratoconus that would classify as having "normal topography" using the published criteria for very asymmetric ectasia with normal topography of KISA% less than 60 and IS value less than 1.45. All controls had a KISA% index value of less than 15. The optimal cut-off value to distinguish cohorts was 15.31 (AUROC = 0.972, 93.75% sensitivity). KISA% index values of 60 and 100 achieved low sensitivity (80% and 73.75%, respectively). CONCLUSIONS: The KISA% index misclassified a significant proportion of eyes with progressive keratoconus as normal. Although highly specific for clinical keratoconus, the KISA% index lacks sensitivity, does not effectively discriminate between normal and abnormal topography, and thus should not be used in large data analysis or artificial intelligence-based modeling. [J Refract Surg. 2024;40(9):e614-e624.].

[Comparative assessment of the state of the cornea after YAG-laser interventions on anterior segment structures]. / Sravnitel'naya otsenka sostoyaniya rogovitsy posle YAG-lazernykh vmeshatel'stv na strukturakh perednego segmenta glaza.

YAG-laser interventions are associated with the risk of complications, including in the cornea. PURPOSE: This study evaluates the condition of the cornea after laser discission (LD) of secondary cataracts (SC) and laser iridectomy (LI) using corneal confocal microscopy (CCM). MATERIAL AND METHODS: Group 1 included patients with the diagnosis "Pseudophakia, secondary cataract", they underwent LD of SC. Patients of group 1 were divided into 2 subgroups depending on the initial state of the cornea: group 1A included patients with unaltered corneas; group 1B - with changes in the corneas. Group 2 included patients diagnosed with angle-closure glaucoma (ACG) or suspected ACG, they underwent LI. CCM was performed on the Heidelberg HRT-III system. Laser treatment was performed using the Nd:YAG-laser LPULSA SYL-9000, λ=1.064 µm. RESULTS: Immediately after treatment, subgroup 1A exhibited singular hyperreflective deposits and negligible endothelial cell loss (ECL). After 1 month, CMM findings revealed no changes in this subgroup. In subgroup 1B, a post-LD reduction in endothelial cell density led to increased polymegathism, decreased pleomorphism, heightened endothelial cell nucleus reflectivity, and moderate hyperreflective deposits after 1 month. In the second group, significant hyperreflective deposits of various sizes, increased nucleus reflectivity, and notable endothelial cell density reduction were observed immediately and 1 month after LI. CONCLUSION: The results of this study show that the possibility of developing corneal complications after photo destructive laser interventions is to a certain extent related to the initial state of the cornea. The risk of developing corneal damage increases with decreasing distance between the cornea and the irradiated structure. An increase in the level of laser radiation energy and its total values also contributes to damage to the cornea, which is possible with dense secondary cataracts and thick irises.

Study of corneal and retinal thicknesses at five years after FS-LASIK and SMILE for myopia.

BACKGROUND: This study aimed to observe corneal and retinal thicknesses at 5 years after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) for myopia, investigate the effect of epithelial remodeling on refractive status and visual quality, and compare retinal thicknesses among fundus tessellation grades. METHODS: Patients who received FS-LASIK or SMILE 5 years before were enrolled in this cross-sectional study. After 1:1 propensity score matching, each surgical group obtained 177 patients (177 eyes). Examinations including visual acuity, refraction, corneal and retinal thicknesses, corneal higher-order aberrations (HOAs), and fundus photography were performed in this visit at 5 years after surgery. The Quality of Vision (QoV) questionnaire was used to assess visual symptoms and overall satisfaction. Corneal and retinal thicknesses between groups were compared, contributing factors were analyzed, and correlations with postoperative refractive status, HOAs, QoV scores and overall satisfaction were evaluated. RESULTS: The discrepancy of epithelial thickness between central and pericentral zones in FS-LASIK group was larger than that in SMILE group, which was negatively correlated with postoperative spherical equivalent (SE), positively correlated with spherical aberration (all P < 0.05), but not correlated with QoV scores and overall satisfaction (all P > 0.05) in both surgical groups. There was no statistical difference in stromal thickness and total corneal thickness (all P > 0.05). Most annuluses of epithelial and stromal thicknesse were linearly related to preoperative SE (all P < 0.05). The macular thickness, ganglion cell complex thickness, and retinal nerve fiber layer thickness exhibited comparable values between two surgical groups and four fundus tessellation grades, with no significant association observed with postoperative SE (all P > 0.05). CONCLUSION: The tendency that epithelial thickness in central zone was thicker than peripheral zone was more obvious at 5 years after FS-LASIK compared to SMILE. This uneven distribution of epithelial thickness might play a role in myopic regression and the changes in HOAs, especially in patients with high myopia, but it had little effect on patients' subjective visual quality and satisfaction. Retinal thicknesses were not affected by these two surgical methods, and they did not appear to be the clinical indicators for myopic regression or fundus tessellation progression.

Analysis of corneal remodeling post-myopic photorefractive keratectomy with the WaveLight® EX500 excimer laser.

Refractive error is becoming a significant public health issue. Photorefractive Keratectomy (PRK) is a corneal surface surgical technique that removes the corneal epithelium before stromal photoablation by ultraviolet radiation from the Excimer laser. We designed a retrospective study to characterize corneal remodeling after myopic Photorefractive Keratectomy and assess the accuracy of laser-predicted ablation depth (AD). This study took place in 15-20 National Ophthalmology Hospital, Paris, France. 150 eyes with preoperative manifest spherical equivalent between - 10.00D and - 0.25D and cylinder < 3D, treated with the WaveLight® EX500 laser between 01/2019 and 01/2023, were followed for at least three months. The main outcome measurements were postoperative changes in epithelial (ET) and stromal (ST) thicknesses measured with spectral domain optical coherence tomography and mean simulated keratometry (SimK) assessed with corneal topography. The central ET significantly decreased at M1, increased over the preoperative value from M1 to M6, and stabilized after M6. The increase in central ET after M1 was associated with an increase in mean SimK (r = 0.34). The achieved AD was 7.9 ± 8.0 µm greater than the laser-predicted AD. Stromal over-ablation was significantly and independently associated with myopia > 6D preoperative mean SimK > 44D and transepithelial procedures.

Central corneal thickness and topographic indices in Malaysian children with vernal keratoconjunctivitis.

INTRODUCTION: Vernal keratoconjunctivitis (VKC) is a chronic allergic disease characterised by intense ocular surface symptoms and corneal involvement. There is limited data about the corneal changes in children with VKC based on severity of the disease. We aimed to compare the central corneal thickness (CCT) and corneal topographic indices in Malaysian children with VKC, as well as among the varying grades of VKC severity. MATERIALS AND METHODS: This study is a comparative, crosssectional and hospital-based study. We recruited 83 children with VKC and 83 healthy children as controls. All children underwent complete ocular examinations, CCT measurement using an ultrasound pachymeter and corneal topography using a Placido disc corneal analyser. RESULTS: There was a statistically significant difference of means CCT and topographic indices in children with VKC compared to controls (p<0.05). The probability keratoconus reached 18% in children with VKC. The mean CCT was observed to be thinnest in the severe-to-very severe groups of VKC compared to the mild-to-moderate (p<0.05). The means simulated-K1 and -K2, apical keratometry, apical gradient curvature, superior-inferior index and keratoconus prediction index were significantly different in severe-tovery severe VKC compared to mild-to-moderate VKC and controls (p<0.05). However, there was no significant difference in mean cylinder value and percent probability keratoconus when comparing different groups of severity of VKC (p=0.912 and 0.070 respectively). CONCLUSION: Children with VKC have thinner CCT and topographic indices changes compared to healthy children. Similar pattern was observed between groups with VKC. Degree of astigmatism and probability of keratoconus were similar in mild-to-moderate and severe-to-very severe groups.

The KERATO Biomechanics Study 1: A Comparative Evaluation Using Brillouin Microscopy and Dynamic Scheimpflug Imaging.

PURPOSE: To assess the corneal biomechanical properties in normal individuals and patients with keratoconus using the Brillouin optical scanning system (Intelon Optics) (BOSS) and compare them with ultra-high-speed Scheimpflug imaging (Corvis ST; Oculus Optikgeräte GmbH). METHODS: Sixty eyes from 60 patients (30 normal and 30 keratoconus) were included in this prospective, single-center, comparative, non-interventional study. Corneal biomechanics were evaluated using the Corvis ST and the BOSS. With the BOSS, each corneal image was acquired three times, measuring 10 locations within an 8-mm diameter. Parameters extracted included mean, maximum, and minimum Brillouin shift. These 10 points were also grouped into superior, central, and inferior regions. BOSS repeatability was assessed using the coefficient of repeatability and coefficient of variation. Furthermore, normal individuals and patients with keratoconus were compared using the Corvis ST and BOSS. RESULTS: The BOSS exhibited good repeatability, with coefficient of repeatability ranging from 0.098 to 0.138 GHz for single points in normal individuals and 0.096 to 0.149 GHz for patients with keratoconus. Statistical analysis revealed significant differences between normal individuals and patients with keratoconus, indicating softer corneas in keratoconus, observed with both the Corvis ST and BOSS. Specifically, the BOSS showed significant differences in mean, inferior, and superior mean, maximum, and minimum Brillouin frequency shift (all P < .05), whereas the Corvis ST displayed highly significant differences in stiffness parameter at first applanation, stress strain index, deformation amplitude ratio, and inverse integrated radius (all P < .001). CONCLUSIONS: Corneal biomechanical measurements proved highly repeatable and effectively demonstrated significant differences between normal individuals and patients with keratoconus using both the BOSS and the Corvis ST. [J Refract Surg. 2024;40(8):e569-e578.].

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

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

Does blepharospasm effect biometric parameters and intraocular lens power calculations?

PURPOSE: To investigate the effect of botulinum toxin-A (BTX-A) treatment on corneal topography, ocular biometry and keratometry in patients with benign essential blepharospasm (BEB) and hemifacial spasm (HFS). METHODS: This study comprised 66 eyes of 33 patients with BEB and 5 eyes of 5 patients with HFS who underwent BTX-A injections consecutively. Refractive error values, tear break-up time (TBUT), corneal topography [corneal power of flat axis (K1) and steep axis (K2), mean corneal power (Km), corneal astigmatism (K2-K1)] and ocular optical biometry [axial length (AL), anterior chamber depth (ACD)] were recorded before BTX-A treatment and 1 month after BTX-A treatment. The researchers calculated the expected emmetropic intraocular lens power (emm-IOL) using the SRK-T, Holladay, Hoffer-Q and Haigis formulas at each examination. RESULTS: K1 (43.48 ± 2.02 vs. 43.57 ± 2.08, p = 0.036), Km (43.91 ± 1.99 vs. 43.99 ± 2.06, p = 0.024) and ACD (3.22 (2.77-3.76) vs. 3.41 (2.99-4.02), p < 0.001) values were found to be significantly higher. The expected emm-IOL according to the SRK-T (21.04 ± 1.6 vs. 20.93 ± 1.6, p = 0.048), Holladay (21.05 ± 1.6 vs. 20.91 ± 1.62, p = 0.037) and Hoffer-Q (21.08 ± 1.65 vs. 20.94 ± 1.68, p = 0.038) decreased significantly. The expected emm-IOL according to the Haigis formula slightly decreased, but it was not significant (p = 0.386). Additionally, TBUT was found to be significantly lower (p < 0.001) after BTX-A injection. Other parameters were not statistically significant (p > 0.05). CONCLUSIONS: Our study is the first in the literature to compare optic biometry data and intraocular lens power calculation formulas before and after BTX-A injection in eyes with BEB and HFS. BTX-A injection could play an important role in changing the keratometric and ACD values. It should be considered that IOL power calculations that might be unpredictable due to blepharospasm, so repeated measurements and especially measurements after releasing the spasm with BTX-A injections, are necessary in BEB and HFS.

Early Detection of Subclinical Corneal Abnormalities: Biophotonic Imaging Reveals Hyporeflective Bleb-Like Structures in Asymptomatic Eyes.

BACKGROUND This case report illustrates the incidental detection of atypical hyporeflective bleb-like structures in an otherwise asymptomatic human cornea, highlighting the effectiveness of non-invasive biophotonic imaging techniques such as optical coherence tomography (OCT) and large-area confocal laser scanning microscopy (CLSM). CASE REPORT A 57-year-old man underwent a comprehensive ophthalmological examination, including slit-lamp biomicroscopy, corneal topography, and densitometry, as part of a clinical study. The patient presented with a clear cornea, a deep and optically empty anterior chamber, and a clear crystalline lens in both eyes. Best-corrected distance visual acuity was -0.1 logMAR. He denied ocular pain, tearing, or photophobia. There was no history of ocular trauma, infectious or genetic diseases, or ocular surgery. Further, OCT and large-area CLSM were employed for a more in-depth analysis of the corneal structure. Standard ophthalmological assessments indicated normal ocular health with no apparent corneal abnormalities. High-resolution OCT and large-area CLSM imaging revealed atypical hyporeflective bleb-like structures within the corneal epithelium and sub-basal nerve plexus but not in the stroma. CONCLUSIONS The authors hypothesize that the observed findings may indicate an early stage of epithelial basement membrane dystrophy, potentially preceding the manifestation of clinical symptoms, detectable solely through advanced biophotonic imaging methods. It is important to emphasize that these observations do not represent a definitive diagnosis. Nevertheless, the discovery of these atypical structures via advanced imaging underscores the importance of incorporating non-invasive biophotonic techniques into preoperative eye examinations in certain situations. This approach could significantly improve the early detection and management of corneal diseases, leading to improved patient outcomes.

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.

Clinical outcomes and significance of postoperative ultrasound biomicroscopy in patients with Boston type 1 keratoprosthesis.

PURPOSE: To determine the clinical outcomes in patients after type 1 Boston keratoprosthesis surgery and the significance of ultrasound biomicroscopy imaging for postoperative follow-up. METHODS: This retrospective analysis included 20 eyes of 19 patients who underwent corneal transplantation with type 1 Boston keratoprosthesis between April 2014 and December 2021. Data on patient demographics, preoperative diagnosis, visual acuity, and postoperative clinical findings were analyzed. RESULTS: Type 1 Boston keratoprosthesis implantation resulted in intermediate- and long-term positive outcomes. However, blindness and other serious complications such as glaucoma, retroprosthetic membrane formation, endophthalmitis, or retinal detachment also occurred. The use of ultrasound biomicroscopy imaging allowed for better evaluation of the back of the titanium plate, anterior segment structures, and the relationship of the prosthesis with surrounding tissues, which provided valuable postoperative information. CONCLUSION: Regular lifetime monitoring and treatment are necessary in patients who undergo Boston type 1 keratoprosthesis implantation for high-risk corneal transplantation. ultrasound biomicroscopy imaging can be a valuable imaging technique for the evaluation of patients with Boston type 1 keratoprosthesis, providing important information on anterior segment anatomy and potential complications. Further studies and consensus on postoperative follow-up protocols are required to optimize the management of patients with Boston type 1 keratoprosthesis.

Evaluation of perioperative pachymetry of thin corneas during corneal crosslinking using hypo-osmolar riboflavin and hydroxypropyl methylcellulose.

PURPOSE: This study aimed to analyze variations in intraoperative corneal thickness during corneal cross-linking in patients with keratoconus and to investigate its possible correlation with presurgical maximal keratometry (Kmax) and pachymetry. METHODS: This was a prospective case series. We used a method similar to the Dresden protocol, with the application of hydroxypropyl methylcellulose 0.1% hypo-osmolar riboflavin in corneas between 330 and 400 µm after epithelium removal. Corneal thickness was measured using portable calipers before and immediately after epithelium removal, and 30 and 60 min after the procedure. RESULTS: The 30 patients in this study were followed up for one year. A statistically significant difference was observed in pachymetry values during the intraoperative period (p<0.0001) and an increase of 3.05 µm (95%C1: 0.56-5.54) for each diopter was seen after epithelium removal (p0.019). We found an average Kmax difference of -2.12 D between men and women (p0.013). One year after treatment, there was a statistically significant reduction in pachymetry (p<0.0001) and Kmax (p0.0170) values. CONCLUSIONS: A significant increase in pachymetry measurements was seen during the procedure, and most patients showed a regression in Kmax and pachymetry values one year after surgery.

Comparative analysis of surgically induced astigmatism following cataract surgery: influence of previous myopic correction and corneal parameters.

PURPOSE: This retrospective study investigated the impact of corneal parameters on surgically induced astigmatism (SIA) in eyes with prior myopic correction undergoing cataract surgery. SETTING: Department of Ophthalmology, San Marino Hospital, San Marino, Republic of San Marino. DESIGN: This case-control study analyzed existing data retrospectively, without randomization or masking. METHODS: Eighty eyes divided in group 1 (40 eyes previous underwent refractive surgery for myopia) and group 2 ( 40 myopic eyes) that underwent cataract surgery with intraocular lens (IOL) implantation were included. SIA was calculated using values from the IOL Master Zeiss 700 and mean pupil power (MPP) derived from the CSO Sirius Topographer (based on 3 mm pupil size) with vectorial analysis from doctor Hill software. RESULTS: No significant difference in SIA was observed between eyes with prior myopic photorefractive keratectomy and the control group (p > 0.05). SIA calculations using the IOL Master and CSO Sirius Tomographer yielded similar results. There was no significant correlation between SIA and axial length, corneal curvature, peripheral corneal thickness, or anterior chamber depth (p > 0.05). However, an inverse correlation was found between SIA and horizontal corneal diameter (p < 0.05). CONCLUSIONS: Corneal parameters, such as axial length, corneal curvature, peripheral corneal thickness, and anterior chamber depth, showed no significant influence on SIA. The inverse correlation between SIA and horizontal corneal diameter in study group suggests potential influence of white-to-white distance on SIA. These findings highlight the importance of considering corneal parameters for optimizing surgical outcomes.

Repeatability and reproducibility of a new method for centration analysis via optical zone tangent points after corneal refractive surgery.

PURPOSE: To investigate the repeatability and reproducibility of a new method for centration analysis after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK). METHODS: This study comprised 29 eyes treated with SMILE and 24 with FS-LASIK. Decentrations were analyzed using tangential and pachymetry difference maps respectively. Both difference maps were generated with a Scheimpflug tomographer (Pentacam) for each eye, using preoperative and 3-month postoperative scans. Repeatability and reproducibility were evaluated by calculating the intraclass correlation coefficient (ICC), within-subject standard deviation (Sw), and coefficient of repeatability (CR). RESULTS: ICC, Sw, and CR showed good to excellent repeatability in locating the coordinates of the optical zone (OZ) center on both maps, with values ranging from 0.84 to 0.96, 0.03 to 0.13, and 0.08 to 0.36 respectively. The repeatability of the total decentration from the preoperative corneal vertex on the tangential curvature difference maps( d TC ) and the pachymetry difference maps( d PC ) were moderate and good, respectively. The ICC, Sw, and CR of d TC were 0.63, 0.09, and 0.25, respectively. The ICC, Sw, and CR of d PC were 0.77, 0.10, and 0.28, respectively. The reproducibility of the OZ center measurements was excellent for the tangential difference maps (ICC ≥ 0.97 ) and good for the pachymetry difference maps (ICC ≥ 0.86). ICC, Sw, and CR showed excellent reproducibility of d TC , with values of 0.95, 0.03, and 0.08, respectively. ICC, Sw, and CR showed good reproducibility of d PC , with values of 0.89, 0.06, and 0.17, respectively. CONCLUSION: The centration analysis method used in this study showed good to excellent repeatability and reproducibility in locating the coordinates of the center of the OZ on the tangential and pachymetry difference maps.

Distribution and associated factors of keratometry and corneal astigmatism in an elderly population.

To determine the distribution of keratometry and corneal astigmatism (CA) and their association with demographic factors, systemic parameters, anthropometric measures, ocular biometric indices, and refractive errors in people aged 60 years and above. In this cross-sectional study, 160 clusters were randomly selected from Tehran city (Iran) using the multi-stage cluster sampling method. All participants underwent optometric examinations including testing uncorrected and best-corrected distance visual acuity, non-cycloplegic autorefraction, and subjective refraction. Pentacam imaging for all participants was carried out using Pentacam AXL. Keratometry and CA were reported based on Pentacam's data. The average, standard deviation (SD) and 95% confidence interval (CI) of flat keratometry (Kf), steep keratometry (Ks), mean keratometry (mean K), and CA were 44.02 ± 1.58 D (95% CI 43.94-44.1), 44.86 ± 1.67 D (95% CI 44.78-44.94), 44.44 ± 1.58 D (95% CI 44.36-44.52), and 0.84 ± 0.74 D (95% CI 0.81-0.87), respectively. The 95% and 99% percentiles of mean K were 47.1 and 48.6 D, respectively. According to the multiple generalized estimating equation model, the mean K was significantly higher in males, in myopes, and in those with higher systolic blood pressure. Moreover, the mean K was inversely related to the axial length, height, anterior chamber depth (ACD), corneal diameter, and central corneal thickness (CCT). The prevalence of various types of CA based on a cut-off > 0.50 D was as follows; with-the-rule: 32.5% (95% CI 30.6-34.4), against-the-rule: 18.2% (95% CI 16.7-19.7), and oblique: 10.0% (95% CI 9.1-11.0). The present study investigated the normal distribution of keratometry and CA in individuals ≥ 60 years, and results can be used in clinical matters, especially in intraocular lens power calculation. Sex, systolic blood pressure, height, and some biometric components such as ACD, corneal diameter, and CCT were significantly related to keratometry and should be considered.

Multimodal Approach in Dry Eye Disease Combining In Vivo Confocal Microscopy and HLA-DR Expression.

Purpose: The purpose of this study was to determine the association between corneal images provided by in vivo confocal microscopy (IVCM) with clinical parameters and conjunctival expression of HLA-DR antigen in patients with dry eye disease (DED). Methods: Two hundred fourteen eyes of 214 patients with DED were analyzed, consisting of 2 groups of patients - 63 with autoimmune dry eye disease (AIDED) and 151 with non-autoimmune dry eye disease (NAIDED). Patients underwent a full clinical examination, including symptom screening, using the Ocular Surface Disease Index (OSDI) questionnaire, and objective analysis of DED signs by Schirmer's testing, tear break-up time (TBUT), Oxford's test, and IVCM corneal imaging. The IVCM scoring criteria were based on corneal sub-basal nerve density (ND), nerve morphology (NM), and inflammatory cell (IC) density. Quantification of conjunctival HLA-DR antigen was performed by flow cytometry. Results: The total IVCM score (T-IVCM) as well as the IVCM-IC subscore (sc) were positively correlated with HLA-DR levels with r = 0.3, P < 0.001 and r = 0.3, P < 0.01, respectively in the total population of patients with DED. The IVCM-NDsc was negatively correlated with TBUT in patients with AIDED (r = -0.2, P < 0.05) and with the Schirmer's test in patients with NAIDED (r = -0.24, P < 0.05). However, the IVCM-NMsc was positively correlated with the Oxford score only in patients with AIDED (r = 0.3, P < 0.05). Conclusions: The proposed IVCM scoring system showed significant correlations with clinical parameters along with conjunctival HLA-DR quantification in patients with DED. Translational Relevance: The IVCM grading score represents an interesting point of commonality among clinical parameters, imaging, and molecular investigation of the ocular surface.