Anterior Optical Coherence Tomography Research Articles

Comparative analysis of biometry and anterior chamber metrics in the eyes of extreme hyperopic and emmetropic children

PurposeTo investigate the clinical and biometric features of pediatric eyes with extreme hyperopia and report baseline biometric values. MethodsIn this prospective case-control study, the biometric parameters of eyes in children with extreme hyperopia were compared to those of an emmetropic cohort of similar age. Comprehensive eye examinations were conducted for new patients. Anterior OCT (CASIA-2, Tomey) and ocular biometry imaging (IOL Master 700, Zeiss) were performed for all participants. ResultsA total of 19 children (mean age, 12.3 ± 2.3 years) with extreme hyperopia (+8.84 ± 0.77) were compared with 17 emmetropic (+0.53 ± 0.43) controls of similar age (mean age, 12.4 ± 2.2 years [P = 0.864]). Extreme hyperopic eyes exhibited significantly shorter axial length, normal spherical equivalent corneal keratometry, higher astigmatism, lower anterior chamber area and volume, and narrower iridotrabecular angle optical coherence tomography (OCT) parameters. Lens thickness and curvature were similar, with a slightly anterior and tilted position. ConclusionsIn our study cohort, extreme hyperopia was associated with shorter axial length, reduction in anterior chamber size, with well-formed, regular-sized lens positioned anteriorly, and a narrower iridotrabecular angle.

Acute effects of swimming goggle wearing on intraocular pressure, anterior chamber biometrics, and optic nerve head morphology

Swimming goggles (SG) are widely used in water sports, and this study aimed to evaluate the acute effects of wearing SG on intraocular pressure (IOP), anterior chamber biometrics, axial length (AL), and optic nerve head (ONH) morphology. Twenty-eight healthy young adults participated in this cross-sectional study, with assessed parameters including IOP, central corneal thickness (CCT), anterior chamber depth (ACD), anterior chamber angle (ACA), AL, and optical coherence tomography (OCT) imaging of the ONH, specifically Bruch membrane opening (BMO), Bruch membrane opening-minimum rim width (BMO-MRW), lamina cribrosa depth (LCD), and prelaminar tissue (PLT). Measurements were taken at four time points: before wearing SG, at the 1st and 10th minutes of wearing, and immediately after removal. The results showed a significant increase in IOP at the 1st and 10th minutes of SG wear compared to pre-wear and post-removal values. Additionally, decreases in CCT, ACD, and ACA, along with an increase in AL, were observed while wearing SG. However, these changes reverted to baseline after the goggles were removed. No significant alterations were detected in ONH parameters during the study. The findings suggest that wearing SG induces an acute rise in IOP and changes in anterior segment parameters, likely due to oculopression, but does not appear to affect ONH morphology in the short term. Further studies are needed to investigate any potential long-term effects.

Anterior High-Resolution Optical Coherence Tomography in the Diagnosis and Therapeutic Monitoring of Ocular Surface Squamous Neoplasia.

Ocular surface squamous neoplasia (OSSN) is the most common tumor of the ocular surface, ranging from mild dysplasia to invasive squamous carcinoma. Traditionally, the diagnosis of OSSN relies on histopathological confirmation followed by a full-thickness biopsy. However, in the past two decades, the therapeutic approach to OSSN has shifted from surgical intervention to topical chemotherapy regimens in clinical settings. This shift emphasizes the need for less invasive or non-invasive methods to diagnose ocular surface pathologies. Among various imaging devices, commercially available high-resolution optical coherence tomography (HR-OCT) has emerged as a powerful tool for the characterization of OSSN. HR-OCT provides an in vivo, cross-sectional view of ocular surface lesions, offering an "optical biopsy" for OSSN with high sensitivity and specificity. It provides valuable information in differentiating intraepithelial or invasive OSSN from other benign lesions. Additionally, HR-OCT can be used to monitor the response to topical chemotherapy and to detect subclinical OSSN during follow-up visits. In this article, the scanning protocol for image acquisition is presented, and image interpretation for OSSN is outlined. This standardized, practical, and reproducible approach is recommended in clinical workflows and is expected to assist clinicians in the management of OSSN.

Late Onset Corneal Haze Post Photorefractive Keratectomy

Introduction: Photorefractive keratectomy (PRK) is a surface ablation procedure to correct refractive errors. Regardless of the safety and efficacy, corneal haze may occur after PRK, and it remains one of the most feared complications because it can impair good visual outcomes. Case Presentation: A 20-year-old woman complained of blurred vision in her right eye (RE) after undergoing PRK elsewhere six months before admission with a history of refraction of S-12.75 C-1.75 x 10° preoperatively and S-0.75 postoperatively. Six-month postoperative uncorrected visual acuity (UCVA) was 0.01, best corrected visual acuity (BCVA) was 0.5 with S-7.00 C-0.75 x 50°. A slit lamp examination revealed grade three corneal haze. Anterior optical coherence tomography (OCT) showed the hyperreflective area with 132 μm deep into the stroma. The patient underwent phototherapeutic keratectomy (PTK) and mitomycin-C (MMC) treatment to a depth of 50 μm Ø6.5mm transition zone 0.5 mm. Two months later, UCVA was 0.2, BCVA was 0.63 with S-2.50 C-0.50 x 90°, and slit lamp examination revealed no haze remaining. Conclusions: This case illustrates the potential risk for corneal haze development, mainly when PRK is performed at greater treatment depths. However, with phototherapeutic keratectomy and mitomycin-C treatment, an excellent visual outcome and vision restoration can be obtained.

Intraocular Epithelial Ingrowth after Traumatic and Surgical Corneal Injuries.

Intraocular epithelial ingrowth is a rare but serious complication of eye surgery or trauma. The diagnosis is challenging but can be aided by techniques such as anterior optical coherence tomography (AS-OCT). This study aimed to compare clinical and histopathological diagnostic data to evaluate the accuracy of AS-OCT. This retrospective analysis focused on patients presenting with suspected epithelial invasion between 2017 and 2022. Clinical data and histopathological findings were analyzed for diagnostic confirmation. Immunohistochemistry using the corneal-specific marker cytokeratin 3 and the conjunctival-specific marker cytokeratin 13 helped to identify the type of invading epithelial cells. Statistical analysis was used to evaluate the effectiveness of AS-OCT for diagnosis. This study included 51 patients who underwent keratoplasty or enucleation. Sixteen cases (31%) of epithelial ingrowth were histologically confirmed. The most common type was the cystic form (82%). Enucleation was required in 25% of patients, mainly due to diffuse epithelial invasion. Immunohistochemistry revealed a conjunctival origin in 82% of the infiltrated cells. AS-OCT showed a sensitivity of 78% and a specificity of 26% in detecting hyperreflective structures associated with epithelial invasion. This study highlights the diverse manifestations of epithelial ingrowth and the need for improved diagnostic techniques, with AS-OCT showing promising results but requiring further validation to avoid misdiagnosis.

Effect of Temporal Decentration of Orthokeratologic Lens on Corneal Aberrations in Swept-source Optical Coherence Tomography

Purpose: This study used anterior segment swept-source optical coherence tomography (AS SS-OCT) to explore the effect of temporal decentration within the orthokeratologic lens treatment zone on corneal aberrations.Methods: After lens placement, AS SS-OCT was used to evaluate anterior, posterior, and total corneal astigmatism and the magnitudes of the individual 1st- to 4th-order aberrations of the anterior and entire corneal fields. Also, the 4th-to 7th-order root mean square (RMS), and the low- and high-ordered RMSs of both the anterior and entire corneal areas were recorded. We compared subjects lacking (the no decentration [ND] group) to those exhibiting (the temporal decentration [TD] group) temporal decentration.Results: In all, 61 eyes of 32 patients (44 eyes in the ND group and 17 in the TD group) were included. In the TD group, the average temporal decentration was 0.74 ± 0.15 mm. The baseline axial length, spherical equivalent, anterior mean corneal power, and anterior corneal astigmatism did no difference between the two groups. However, the TD group exhibited more anterior and total corneal horizontal tilts, and horizontal coma, than the ND group. That group also had less with-the-rule (WTR)/against-therule (ATR) astigmatism, elevated anterior and total corneal 5th-order RMS values, and greater low- and high-ordered RMS levels. However, despite these differences, the extent of myopia correction did not significantly differ between the groups.Conclusions: Although myopia reduction was not significantly compromised by temporal decentration of an orthokeratologic lens, the anterior and total corneal low- and high-ordered RMS values increased. In terms of individual aberrations, the low-ordered horizontal tilt and the high-ordered horizontal coma increased.

Anterior segment swept-source optical coherence tomography and ultrasound biomicroscopy in iris and ciliary body lesions

ABSTRACT Objectives Differentiation of iris and ciliary body lesions as benign or malignant and cystic or solid is important. The aim of this study was to compare anterior segment swept-source optical coherence tomography (AS SS-OCT) and ultrasound biomicroscopy (UBM) findings in iris and ciliary body tumors. Research design and methods Forty-two eyes of 38 cases with iris and ciliary body tumors imaged with UBM and AS SS-OCT between September 2018 and September 2023 were evaluated retrospectively. Results Of 42 eyes, 14 had melanoma, 14 iris pigment epithelial (IPE) cysts, 7 nevi, 3 Lisch nodules, 2 iris stromal cysts, 1 pars plana cysts, and 1 iris mammillations. An equivalent (100%) visualization of the anterior tumor margin was obtained with both techniques. Compared to AS SS-OCT, UBM was superior for posterior margin visualization in melanocytic tumors and IPE cysts. Bland-Altman plots demonstrated good agreement between UBM and AS SS-OCT for melanocytic tumors < 2.5 mm in base diameter and < 2 mm in thickness. Conclusions Although, UBM is the gold standard for ciliary body and iridociliary tumors. AS SS-OCT should be considered as an excellent alternative to UBM, especially in minimally elevated iris lesions.

Timing optimization for primary pterygium excision with conjunctival-limbal autograft to restore the corneal optical properties.

To propose the optimal value of baseline corneal astigmatism and pterygial morphological profiles for primary pterygium surgery to restore the corneal optical properties. We analysed 93 eyes from 84 subjects with nasal-only primary pterygium who underwent pterygium excision with conjunctival-limbal autograft and were assessed perioperatively using anterior segment swept-source optical coherence tomography (AS SS-OCT). We collected data on anterior corneal astigmatism (ACA) and root mean square (RMS) values for anterior corneal lower- (LoA) and higher-order aberrations (HoA) as corneal optical properties using AS SS-OCT. Using preoperative ACA and four pterygial morphological profiles (horizontal invasion length [HIL], height, thickness and the ratio of residual corneal thickness [RCT] to central corneal thickness [CCT]) measured in AS SS-OCT, we plotted receiver operating characteristic (ROC) curves. These curves aimed to determine cut-off values predicting a perioperative decrease exceeding 50% in ACA, RMS LoA and RMS HoA, as well as postoperative residual ACA higher than 1.25D. Preoperative ACA > 1.42D (AUC = 0.934) and >3.60D (AUC = 0.946) proved most effective in identifying subjects with perioperative decrease exceeding in ACA and RMS LoA, respectively. HIL > 3.34 mm (AUC = 0.941) was most effective in distinguishing subjects with perioperative reduction exceeding 50% in RMS HoA. Preoperative ACA > 5.78D (AUC = 0.776) and HIL > 5.03 mm (AUC = 0.700) significantly distinguished subjects with postoperative residual ACA higher than 1.25D. Optimizing the restoration of corneal astigmatism and aberrations after pterygium surgery may be facilitated by determining the optimal surgical timing based on preoperative ACA and HIL values.

Analysis of intraocular lens decentration and tilt after femtosecond laser-assisted cataract surgery using swept-source anterior optical coherence tomography

ObjectiveTo evaluate and compare the magnitude of intraocular lens (IOL) decentration and tilt following conventional and femtosecond laser-assisted cataract surgery (FLACS) using swept-source anterior optical coherence tomography (SS-OCT). MethodsIn this retrospective observational study, we enrolled patients who underwent conventional cataract surgery or FLACS with the implantation of hydrophobic 1-piece monofocal IOL. The magnitude of IOL decentration and tilt were measured using SS-OCT. Visual acuity, intraocular pressure, spherical equivalent, axial length, contrast sensitivity, and satisfaction questionnaire were evaluated before and one-month post-surgery. Additionally, postoperative internal cylinder measurements were obtained using a wavefront aberrometer. Correlation factors between each parameter and IOL decentration or tilt were analyzed. ResultsThis study included 100 eyes from 100 patients. Mean IOL decentration and tilt were 0.21 ± 0.13 mm and 5.01 ± 1.49°, respectively. Conventional cataract surgery (versus FLACS, P = 0.001) and male sex (versus female, P = 0.047) were significantly correlated with higher postoperative decentration. Preoperative lens diameter (P < 0.001), preoperative lens tilt (P = 0.007), and preoperative intraocular pressure (P = 0.027) were correlated with higher postoperative tilt. Fifty eyes that underwent FLACS demonstrated mean postoperative decentration of 0.21 ± 0.13 mm and tilt of 4.64 ± 1.48°. Compared with the conventional surgery group, the FLACS group significantly differed in postoperative decentration (0.30 ± 0.12 mm, P < 0.001) but not in tilt (5.03 ± 1.35°, P = 0.173). Postoperative visual acuity did not significantly differ between the two groups. ConclusionPatients who underwent FLACS demonstrated better IOL decentration and tilt than those who underwent conventional cataract surgery one-month post-surgery. However, differences in IOL decentration and tilt did not affect postoperative visual acuity.

Chronic inflammation as a proposed risk factor for ocular surface squamous neoplasia

Chronic inflammation is a predisposing factor for metaplastic changes and ultimately dysplasia. We describe cases of OSSN occurring in the setting of chronic ocular surface inflammation. Sixteen eyes from 14 individuals were included from one ocular oncology clinic between 2010 and 2023. Patients presented with ocular surface squamous neoplasia (OSSN) in the setting of chronic inflammation. The diagnosis of OSSN was made using anterior segment high-resolution optical coherence tomography (HR-OCT) and confirmed by histopathological analysis in all cases. Median age on presentation was 61 [IQR 47.5-69.2] years. Eleven (86%) individuals were male and five (36%) identified as White Hispanic. Ten eyes were referred with ocular surface diagnoses including pannus (n=4), scarring (n=3), pterygium (n=2), and herpetic keratitis (n=1). Only six eyes were referred as possible neoplasia. All individuals had a history of ocular surface inflammation. The most common inflammatory conditions were ocular rosacea (seven individuals) and atopic keratoconjunctivitis (AKC) (five individuals). Two individuals were found to have bilateral OSSN, one in the setting of ocular rosacea and the other in the setting of AKC. All 16 eyes from 14 individuals were suspected to have OSSN based on HR-OCT findings which guided the location of the incisional biopsies that subsequently confirmed histopathological diagnosis in all cases. OSSN may arise in the setting of chronic inflammation on the ocular surface. Identification of the tumor can be challenging in these cases, and HR-OCT can be a key diagnostic tool in detecting OSSN.

High-Fluence Epithelium-off Accelerated Pulsed Corneal Cross-linking (15 mW/cm2; 7.2 J/cm2) for Pediatric Keratoconus: A 3-Year Retrospective Analysis.

To assess the safety and efficacy of treatment and secondarily determine the topographic changes, visual outcomes, and demarcation line depth after high-fluence pulsed light accelerated cross-linking (ACXL) in pediatric patients (younger than 18 years) with progressive keratoconus. This retrospective analysis included 32 eyes (25 children, aged 11 to 18 years), with progressive keratoconus treated with high-energy epithelium-off pulsed light ACXL (7.2 J/cm2, 15 mW/cm2, 12 minutes, 2 seconds on/1 second off). Corrected distance visual acuity (CDVA), Scheimpflug tomography, and anterior optical coherence tomography measurements were recorded preoperatively and 1, 2, and 3 years postoperatively. A total of 32 eyes were included. Significant CDVA improvement, pachymetry, and maximum keratometry reduction were found at all follow-up visits. Mean keratometric values remained stable, and astigmatism showed a mild worsening (< 0.25 D) with statistical significance at 1 and 3 years. Total aberration showed discordant results and coma aberration had a slight improvement without statistical significance. The demarcation line depth was 265 ± 26 μm. Three patients developed mild haze without visual acuity loss. None of the patients underwent a second CXL procedure. In pediatric patients, high-fluence epithelium-off pulsed light ACXL appears to be a safe and effective procedure to halt the progression of keratoconus, slightly improving the CDVA and keratometric values. [J Refract Surg. 2024;40(3):e148-e155.].

Biomechanical properties measured with dynamic Scheimpflug analyzer in central serous chorioretinopathy.

Recent evidence suggests that venous congestion at the vortex vein significantly contributes to the development of central serous chorioretinopathy (CSCR), and sclera is observed to be thicker in affected eyes. This study aims to investigate whether eyes with CSCR exhibit stiff corneas, measured using Corneal Visualization Scheimflug Technology (Corvis ST), which may serve as an indicator of scleral stiffness. This retrospective case-control study comprises 52 eyes from 33 patients diagnosed with CSCR and 52 eyes from 32 normal controls without CSCR. We compared biomechanical parameters measured with Corvis ST and anterior scleral thickness measured using anterior segment swept-source optical coherence tomography between the two groups. Age, sex, axial length, intraocular pressure, and central corneal thickness showed no significant differences between the two groups (p > 0.05, linear mixed model). Three biomechanical parameters-peak distance, maximum deflection amplitude, and integrated inverse radius-indicated less deformability in CSCR eyes compared to control eyes. The stress-strain index (SSI), a measure of stiffness, and anterior scleral thickness (AST) at temporal and nasal points were significantly higher in the CSCR eyes. SSI and AST were not correlated, yet both were significantly and independently associated with CSCR in a multivariate logistic regression model. Eyes affected by CSCR have stiffer corneas, irrespective of thicker scleral thickness. This suggests that stiffer sclera may play a role in the pathogenesis of CSCR.

Simultaneous evaluation of iris area and subfoveal choroidal thickness in Fuchs uveitis syndrome

Background/aimsTo simultaneously evaluate iris area (IA) and subfoveal choroidal thickness (SFCT) in eyes with Fuchs Uveitis Syndrome (FUS).MethodsWe prospectively recruited a case series of patients with FUS at our institution, simultaneously measuring IA with anterior segment spectral domain optical coherence tomography (SD-OCT) and SFCT with enhanced depth imaging optical coherence tomography (EDI-OCT). Iris images were analyzed by ImageJ software. We tested the differences in intereye IA and SFCT with the healthy eye (HE) using the Wilcoxon test, and clinical interpretation was controlled by intraclass correlation coefficient (ICC) between two masked specialists.ResultsSixteen patients with unilateral FUS were included. Six were female, and the age range was 37 to 67 (median age 48 years, IQR 41–60). ICC of 98.9%, with a lower confidence interval of 97%. Eyes with FUS had a significant thinning of the total iris median area (p < 0.002), restricted to the temporal and nasal areas compared to the HE (p < 0.01 and < 0.001, respectively). SFCT was also significantly thinner compared to the HE (p < 0.0001). A low correlation was found between iris and choroidal thinning in FUS eyes (rs = 0.21; p = 0.4).ConclusionsThis study found reduced iris area and subfoveal choroidal thickness in eyes with FUS compared to the normal fellow eye.

Khodadoust Line Indicating Graft Rejection in Descemet’s Stripping Automated Endothelial Keratoplasty: A Unique Case Report

Abstract Purpose: To highlight the rarity of the endothelial rejection line, also known as the Khodadoust line, as a manifestation following Descemet’s stripping automated endothelial keratoplasty (DSAEK). The objective is to present a meticulously detailed case, including imaging and anterior optical coherence tomography (OCT), to enhance understanding and recognition of this phenomenon. Methods: A detailed case presentation involving a 50-year-old male, 3 years post-DSAEK transplantation for endothelial damage resulting from intraocular surgeries. The patient urgently sought consultation due to vision loss while under daily fluorometholone use. Clinical examination revealed acute graft rejection characterized by corneal edema, anterior chamber reaction, and the presence of keratic precipitates forming a Khodadoust line. The management approach included the initiation of a tapered dexamethasone regimen. Results: The identified acute graft rejection, marked by the presence of a Khodadoust line, demonstrated favorable responsiveness to the initiated tapered dexamethasone regimen. Corneal OCT and imaging played crucial roles in providing detailed insights into the manifestation. Conclusions: While the endothelial rejection line (Khodadoust line) is a rare occurrence following DSAEK, this case underscores its potential association with graft rejection. The successful management outlined in this report suggests the importance of prompt recognition and appropriate anti-inflammatory intervention in such cases to achieve positive outcomes.

Influence of Anterior Segment Swept-source Optical Coherence Tomographic Profiles in the Temporal Decentration of Orthokeratology Treatment Zone

Purpose: This study aims to elucidate the factors contributing to the temporal decentration of the orthokeratology lens (OK lens) treatment zone, employing profiles obtained from anterior segment swept-source optical coherence tomography (AS SS-OCT).Methods: The measurements prior to treatment were taken using AS SS-OCT (Anterion; Heidelberg, Germany) in subjects who had worn OK lenses for at least 2 weeks. The collected data encompassed anterior corneal refractive profiles, corneal thickness profiles, anterior corneal elevation profiles, and anterior corneal aberrations. A comparison was drawn between two groups: the temporal decentration (TD) group and the control (no decentration [ND]) group, based on the presence of temporal decentration of the treatment zone.Results: The analysis included a total of 63 eyes (48 eyes in the ND group and 15 eyes in the TD group) from 33 patients (10.6 ± 2.2 y). No significant differences were observed in axial length, spherical equivalent, and horizontal corneal diameter between groups. However, the TD group exhibited higher values in terms of anterior SimK&lt;sub&gt;mean&lt;/sub&gt; (D), central K (D), and anterior K at temporal and nasal 3.0, 2.0, and 1.0 mm points. Moreover, the TD group displayed a higher horizontal meridian to vertical meridian ratio (H/V K ratio at 4.0 mm diameter) of anterior corneal K at 4.0 mm diameter ring. The ND group showed a higher vertical distance to the maximum corneal power (K&lt;sub&gt;max&lt;/sub&gt; y) compared to the TD group. Although high order root mean square aberrations were relatively higher in the ND group, statistical significance was marginally attained (&lt;i&gt;p&lt;/i&gt; = 0.047).Conclusions: The temporal decentration of the OK lens treatment zone was determined to be linked with steeper corneal curvature at the central and horizontal meridians, an augmented relative steepness of the horizontal meridian at the 4.0 mm diameter, and a vertical displacement in K&lt;sub&gt;max&lt;/sub&gt; on AS SS-OCT.

Optical beam scanner with reconfigurable non-mechanical control of beam position, angle, and focus for low-cost whole-eye OCT imaging.

Whole-eye optical coherence tomography (OCT) imaging is a promising tool in ocular biometry for cataract surgery planning, glaucoma diagnostics and myopia progression studies. However, conventional OCT systems are set up to perform either anterior or posterior eye segment scans and cannot easily switch between the two scan configurations without adding or exchanging optical components to account for the refraction of the eye's optics. Even in state-of-the-art whole-eye OCT systems, the scan configurations are pre-selected and cannot be dynamically reconfigured. In this work, we present the design, optimization and experimental validation of a reconfigurable and low-cost optical beam scanner based on three electro-tunable lenses, capable of non-mechanically controlling the beam position, angle and focus. We derive the analytical theory behind its control. We demonstrate its use in performing alternate anterior and posterior segment imaging by seamlessly switching between a telecentric focused beam scan to an angular collimated beam scan. We characterize the corresponding beam profiles and record whole-eye OCT images in a model eye and in an ex vivo rabbit eye, observing features comparable to those obtained with conventional anterior and posterior OCT scanners. The proposed beam scanner reduces the complexity and cost of other whole-eye scanners and is well suited for 2-D ocular biometry. Additionally, with the added versatility of seamless scan reconfiguration, its use can be easily expanded to other ophthalmic applications and beyond.

Evaluation of Schlemm Canal Parameters Using Swept-Source Optical Coherence Tomography in Eyes That Underwent Keratoplasty.

In this study, we aimed to evaluate Schlemm canal parameters using anterior segment swept-source optical coherence tomography in eyes that underwent keratoplasty and compare them with keratoconus and healthy control groups. The study included 32 patients who underwent penetrating keratoplasty or deep anterior lamellar keratoplasty once due to keratoconus and age-matched and sex-matched 20 keratoconus patients and 30 healthy controls. In all the patients, a single horizontal image centered on the central cornea was obtained from the nasal and temporal quadrants with low-intensity scanning to visualize Schlemm canal. There was no statistically significant difference between the groups for age and gender ( P ˃0.05). In the keratoplasty group, the area and diameter of Schlemm canal were 2.266±1.141μm 2 and 160.77±65.08 μm, respectively, in the nasal quadrant and 2.623±1.277 μm 2 and 158.81±68.05 μm, respectively in the temporal quadrant, which were statistically significantly lower compared with other groups ( P <0.001 for all). There was no significant difference between the penetrating and deep anterior lamellar keratoplasty subgroups for Schlemm canal parameters. This is the first study to report anterior segment optical coherence tomography after surgery shows SC parameters that are, on average, less than age-matched and keratoconus controls.

Multiple linear regression model for improving accuracy of capsulorhexis size calculation in femtosecond laser-assisted cataract surgery for adults: a retrospective single-center study

BackgroundDifferences between programmed capsulorhexis diameter and actual resulting capsulorhexis diameter (ARCD) are commonly encountered in femtosecond laser-assisted cataract surgery (FLACS). The purpose of this study was to identify the preoperative ophthalmic variables influencing capsulorhexis diameter index (CDI) in FLACS for adults and create a multiple linear regression model for obtaining a more accurate capsulorhexis diameter.MethodsThis retrospective study involved sixty-seven eyes of 44 patients who received FLACS and intraocular lens implantation. The ARCD was measured using anterior segment swept-source optical coherence tomography (CASIA 2). Keratometry (K1, K2 and average K), anterior chamber depth (ACD), lens thickness (LT), anterior chamber width (ACW), white-to-white (WTW), curvature radius of anterior lens capsule (Front R) and axial length (AL) were all measured preoperatively. Based on the derived data, LT/ACW, LT/AL, LT/ACD and LT/ACW/Front R were calculated. The ratio of the programmed capsulorhexis diameter and ARCD was defined as the CDI. Correlation analysis was conducted to examine the relationship between preoperative variables listed above and the CDI. Multiple linear regression analysis was applied to select the most influential preoperative variables on CDI.ResultsACD, LT, ACW, Front R, AL, LT/ACW, LT/AL, LT/ACD, and LT/ACW/Front R showed significant correlation with CDI. Front R and LT/ACW/Front R were selected as constants in the multiple linear regression model using stepwise variable selection. The following equation represents the multiple linear regression model: CDI = 1.306–4.516 × LT/ACW/FrontR-0.011 × Front R, when P < 0.0001, adjusted R-squared = 0.919, variance inflation factor = 8.389, and Durbin-Watson ratio = 1.846.Predicted postoperative capsulorhexis diameter (PPCD) equation was created based on CDI equation as follows: PPCD = programmed capsulorhexis diameter × 1.306–4.516 × LT/ACW/FrontR-0.011 × Front R.ConclusionFront R and LT/ACW/Front R were found to be the most significant influencing factors of capsulorhexis size. CDI and PPCD calculation equations presented in this study may be useful in setting up more accurate programmed capsulorhexis diameter for FLACS in adults, resulting in a precise ARCD.

MORPHOMETRIC FEATURES OF EYE STRUCTURES ACCORDING TO OCT AND CHANGES IN HEMODYNAMICS IN PATIENTS WITH ANTERIOR UVEITIS COMPLICATED BY OPTIC NEURITIS

Aim. Identify changes in the optic disc and vascular membrane by OCT, as well as features of hemodynamics and the possibility of communication between these parameters. Materials and methods. In 150 patients with idiopathic monolateral anterior uveitis, ophthalmic (visometry, refractometry, tonometry, perimetry, biomicroscopy, direct, reverse ophthalmoscopy), examination, rheophthalmography (ROG) and optical coherence tomography (OCT) of structures were performed. Patients received treatment according to the protocol, including, if necessary, antibacterial, antiviral, steroidal and nonsteroidal anti-inflammatory, immunosuppressive, desensitizing, vasodilating, immunomodulatory drugs. Statistical analysis was performed using Statistica 10.0 using Student's coefficient, pairwise correlation and Spearman's rank correlation Research results. The OCT results of the eyes of patients with optic neuritis on the background of anterior uveitis showed a significant increase in the thickness of the layer of peripapillary nerve fibers and vascular membrane by 34.3 and 38.9% relative to the data in anterior uveitis without complications. ROG revealed a significant increase in the tone of small and large vessels of the eye in neuritis on the background of anterior uveitis by 14.2 and 17.2% compared to those without neuritis. There was a direct significant strong relationship between the thickness of peripapillary fibers and the thickness of the vascular membrane with volumetric pulse blood filling, the volume of volumetric blood filling, tonic properties of large and small vessels (r = 0,699-0,909); average - between the diameter of the optic nerve at the entrance to the orbit and the parameters of the ROG (r = 0,647-0,797); weak - determined in the retrobulbar and middle department (r = 0.241-0.453). The development of neuritis in uveitis is accompanied by an increase in the thickness of the peripapillary fibers and vascular membrane, the diameter of the optic nerve at the entrance to the orbit, in the retrobulbar and middle department, as well as volumetric pulse blood filling, volumetric connection in all cases (Spearman r 0.421-0.754). Conclusions 1. The results of OCT of the eyes with optic neuritis on the background of anterior uveitis showed a significant increase in the thickness of the layer of peripapillary nerve fibers and vascular membrane relative to the data in persons with anterior uveitis without complications. 2. The horn of the tonic properties of the vessels revealed a significant increase in the tone of small and large vessels of the eye with optic neuritis on the background of anterior uveitis relative to those without neuritis. 3. The direct strong reliable correlation of indicators of thickness of peripheral fibers and a vascular cover with volume pulse blood filling, speed of volume blood filling, tonic properties of large and small vessels is revealed. Average connection - between the diameter of the optic nerve at the entrance to the orbit and the parameters of the ROG, weak connection with the diameter of the optic nerve in the retrobulbar and middle department. 4. The development of optic neuritis against the background of anterior uveitis is accompanied by an increase in the thickness of the peripheral fibers and choroid, the diameter of the optic nerve at the entrance to the orbit, in the retrobulbar and middle section. The tonic properties of large and small vessels, volumetric pulse blood filling, and the speed of volumetric blood filling, as indicated by the presence of a significant direct correlation. Key words: chronic anterior idiopathic uveitis, optic neuritis, OCT, eye hemodynamics.

Corneal biomechanical stiffness and histopathological changes after in vivo repeated accelerated corneal cross-linking in cat eyes

Corneal cross-linking (CXL) has been proved efficiency for treating progressive keratoconus and other corneal ectasia diseases by stabilizing corneal geometry and biomechanics. However, the necessity of repeated CXL treatment in patients is unknown. This study aimed to investigate corneal biomechanical stiffness and change in corneal histopathological characteristics after repeated accelerated CXL (A-CXL) in cat eyes. A-CXL was performed with 0.1% riboflavin applied for 10 min, followed by ultraviolet A irradiation at 30 mW/cm2 for 3 min at 365 nm in 15 domestic cats. Corneas (n = 30) were divided into three groups: one-time accelerated corneal cross-linking (A-CXL*1 group), repeated accelerated corneal cross-linking (A-CXL*2 group), and an untreated control group. In A-CXL*2 group, A-CXL was repeated at 1-month intervals. In vivo ocular examinations were performed pre- and postoperatively. Biomechanical analysis was performed using a biotester biaxial testing system. We used the Mooney–Rivlin strain-energy function to describe corneal material properties. No infection in any case after A-CXL was observed. Biomechanical tests showed that the stress-strain curves of the two A-CXL groups were significantly different from those of the control group (P < 0.01), whereas stress-strain curve of the A-CXL*2 group was similar to that of the A-CXL*1 group (P > 0.05). Delayed epithelial healing and haze were observed 1 month after surgery. Stromal demarcation line depth measured with anterior spectral-domain optical coherence tomography was 187.6 ± 20.4 and 197.1 ± 11.5 μm for the A-CXL*1 and A-CXL*2 groups, respectively (P > 0.05). These results show that A-CXL can increase corneal biomechanics in cat eyes. The biomechanical enhancement of cat corneas treated with repeated A-CXL at 1-month intervals was similar to that of performing a one-time A-CXL. Repeated cross-linking procedures at short intervals may increase the risk of adverse reactions, and more caution should be taken in clinical applications.