OCT Measurements Research Articles

PDE6A-Associated Retinitis Pigmentosa, Clinical Characteristics, Genetics, and Natural History

To analyze the genetics, clinical characteristics, and natural history of PDE6A-associated retinitis pigmentosa. Retrospective, longitudinal, observational cohort study. Patients with molecularly confirmed PDE6A-associated retinal dystrophy in a single tertiary referral center. Review of medical records and retinal imaging, including fundus autofluorescence (FAF) imaging and spectral-domain OCT. Genetic results were reviewed, and the detected variants were assessed. Molecular genetic testing, clinical findings including best-corrected visual acuity (BCVA), qualitative and quantitative retinal imaging analysis. Sixteen patients (32 eyes) were identified and evaluated longitudinally. Genetic analysis identified 14 variants in the PDE6A gene, including 8 novel variants. The mean age (± standard deviation, range) was 34.8 years (± 17.4, 12-76) at baseline, with a mean follow-up time of 4.8 years. Best-corrected visual acuity was 0.45 ± 0.45 logarithm of the minimum angle of resolution (logMAR) (range 0.0-1.6) at baseline and 0.65 ± 0.7 logMAR (range 0.0-2.3) at the last visit. Best-corrected visual acuity was similar among eyes in 88% of patients. A hyperautofluorescent ring was observed on FAF in 50% and 43.8% of the eyes at baseline and follow-up visit, respectively, with a mean area of 9.7 ± 4.5 mm2 at baseline and mean of 8.6 ± 4.8 mm2 at the follow-up visit. Mean horizontal ellipsoid zone width (EZW) at baseline was 1765 ± 1093 μm, which decreased to 1580 ± 1077 μm at follow-up. Eighteen eyes exhibited cystoid macular edema at baseline (56%), and 17 eyes (53%) at follow-up. There were statistically significant changes during the follow-up period in terms of BCVA, hyperautofluorescent ring area, and the EZW. This study highlights the natural history of PDE6A-retinopathy. Most patients in this cohort had mild BCVA loss, and slowly progressive disease, based on FAF and OCT measurements. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Optical coherence tomography angiography evaluation of retinal and choroidal microvascular changes in pregnant women with a history of unexplained recurrent spontaneous abortions.

To study retinal and choroidal microcirculation by optical coherence tomography angiography (OCTA) in pregnant women with unexplained recurrent spontaneous abortion (RSA) and to compare them with healthy pregnant and nonpregnant subjects. Pregnant women with an unexplained history of RSA (group 1), healthy pregnant (group 2), and healthy non-pregnant women (group 3) were included in the study. After a thorough ophthalmologic examination:best-corrected visual acuity, intraocular pressure,slit-lamp biomicroscopy, fundus examination,autorefractometer, biometry, and axial length measurement; OCT and OCTA measurements were performed with Swept Source OCT-Angiography (Topcon Co, Japan). The nonpregnant group had higher values for central foveal superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density (VD) and lower values for superior, inferior, and mean VD compared with pregnant groups (p < 0.001). Choriocapillaris values (CC) VD were higher in groups 1 and 2 than in group 3 (p < 0.001). The group with unexplained RSA had a relatively smaller FAZ (foveal avascular zone) area than the group of healthy pregnant women (p:0.047). There were no statistically significant differences between groups in the retina, retinal nerve fiber layer, ganglion cell layer, and choroidal thickness (p > 0.05). Although our study did not identify any etiology in pregnant women with RSA, we observed detectable differences in FAZ area and vessel density values using OCTA, when comparing them with healthy pregnant women and healthy nonpregnant controls. We believe that OCTA, as used in many pathologies such as diabetic and hypertensive retinopathy and retinal vascular occlusion, can also be extended to unexplained RSA both to detect etiology and to monitor treatment in studies with a larger number of patients.

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

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

Assessment of macular microcirculation in patients with multiple sclerosis by swept-source optical coherence tomography angiography

Objective: To investigate the changes in the retinal microcirculation in multiple sclerosis (MS) patients by swept-source optical coherence tomography angiography (SS-OCTA). Patients and Methods: Thirty-seven patients with relapsing-remitting MS and 40 healthy volunteers were included into this crosssectional study. Clinical history, Expanded Disability Status Scale and duration of MS were collected. SS-OCTA by deep range imaging (DRI) OCT measurements were performed on all subjects. Macular perfusion parameters including superficial and deep foveal avascular zones (FAZs, FAZd, respectively) (%), vascular densities of superficial capillary plexus (SCP) (%), deep capillary plexus (DCP) (%) and choriocapillaris (CC) (%) were compared with healthy subjects. Results: Vascular densities of SCP, DCP and CC were found to be statistically lower in the study group compared to the control group (p = 0.02, p = 0.03, p = 0.03, respectively). FAZs and FAZd, areas were significantly higher in the study group (p = 0.02, p = 0.02, respectively). Central macular thickness and subfoveal choroidal thickness were significantly lower than in the control group (p = 0.015, p = 0.047, respectively). Conclusion: Evaluation of retinal blood flow in patients with MS is useful both for understanding the physiopathology of the disease and in the clinical follow-up.

Changes in vessel density patterns assessed with OCTA in patients with diabetic macular edema treated with anti-VEGF therapy

AimsTo determine the presence of sectoral changes in vessel density (VD) patterns induced by vascular endothelial growth factor inhibitors (anti-VEGF) in patients with diabetic macular edema (DME) using optical coherence tomography angiography (OCTA).MethodsProspective, interventional study. A total of 43 patients (63 eyes) were initially enrolled in the study. We performed swept source (SS) OCT and sectorial OCTA measurement to determine parafoveal VD at baseline and after six months of anti-VEGF treatment. In the locations with statistically significant differences in VD between baseline and month 6, we performed univariate and multivariate analyses to determine which, if any, of the baseline variables were associated with the observed changes.ResultsA total of 34 patients (48 eyes) were included in the final analysis. Mean VD decreased from baseline to month 6 (from 45.2 (± 3.5) to 44.6 (± 3.2) % in the SCP and from 50 (± 3.3) to 49 (± 3.9) % in the DCP). The only significant changes in VD were observed in the nasal sector of the deep capillary plexus, with a decrease of 2.9% (p = 0.001). On univariate and multivariate analyses, the only variable significantly associated with changes in VD in the nasal sector after 6 months of treatment was baseline VD in the same sector.ConclusionsAnti-VEGF therapy has a small impact on VD values over time. These variations observed after treatment seems to be related to changes over areas of vascular anomalies and displaced vessels adjacent to cystic areas, with no significant changes over ischemic areas. No correlation was observed between this trend and other clinical baseline features.

Correlation Between Blue Fundus Autofluorescence and SD-OCT Measurements of Geographic Atrophy in Dry Age-Related Macular Degeneration

To compare fundus autofluorescence (FAF) and spectral domain optical coherence tomography (OCT) measurements of geographic atrophy (GA) area and to analyze lesion area changes measured by spectral domain OCT in GATHER1. An assessment reliability analysis using prospective, randomized, double-masked phase 2/3 clinical trial data. GATHER1 examined the efficacy and safety of avacincaptad pegol (ACP) for GA treatment. A post hoc analysis was performed to identify correlations between FAF- and OCT-based measurements of GA. GA area was measured on blue-light FAF images using semiautomatic segmentation software with support from OCT and near-infrared imaging. Machine-learning enhanced, multilayer segmentation of OCT scans were reviewed by human readers, and segmentation errors were corrected as needed. GA area was defined as total RPE loss on cross-sectional B scans. Time points included Months 0, 6, 12, and 18. Additionally, OCT-based GA-area changes between ACP and sham were analyzed. There was a strong correlation (r = 0.93) between FAF and OCT GA area measurements that persisted through 18 months. Mean (SD) differences between OCT and FAF GA measurements were negligible: 0.11 mm2 (1.42) at Month 0, 0.03 mm2 (1.62) at Month 6, -0.17 mm2 (1.81) at Month 12, and -0.07 mm2 (1.78) at Month 18. OCT assessments of GA growth revealed a 30% and 27% reduction at Months 12 and 18, respectively, between ACP and sham, replicating FAF measurements from GATHER1. The strong correlation between blue FAF and OCT measurements of GA area supports OCT as a reliable method to measure GA lesion area in clinical trials.

Donor Cornea Storage Temperature: Investigation of the Time Period Immediately Before Cornea Transplantation Surgery

Purpose: Donor cornea storage temperature seems to affect tissue viability; however, the time period between removal from storage and transplant surgery has not been explored. We investigated the possible impact time at room temperature in the operating room may have on endothelial cell density (ECD) and corneal thickness (CT). Methods: In our simulation, transplant-ineligible corneas underwent 1 of 4 room temperature protocols. ECD (by specular microscopy) and CT (by anterior segment optical coherence tomography [OCT]), measured before and after protocols, were used to explore possible effects of time at room temperature. Control group tissue resided at room temperature only long enough for warming and subsequent ECD and CT measurements. Results: Corneas underwent one of the following protocols: 1) 17 (±1) minutes at room temperature (for baseline OCT measurements; n = 13) followed by 23 minutes at 35°C (to facilitate specular imaging, conducted for all 4 protocols), 2) 60 (±1) minutes (1 hour; n = 8) at room temperature, 3) 187 (±1) minutes (approximately 3 hours; n = 7) at room temperature, and 4) 416 (±1) minutes (approximately 7 hours; n = 7). Statistical analysis showed no significant difference in ECD change (P = 0.353) or CT change (P = 0.415) between protocol groups. Controlling for donor age and death-to-preservation time rendered no statistical significance. Conclusions: Time at room temperature did not seem to significantly influence ECD or CT measured soon after warming. Studies exploring ECD postoperatively and long-term graft survival are needed to assess the possible clinical impact of preoperative time at room temperature.

A comparison of visual electrophysiology measures in optic neuropathy

Aims/Purpose: Our aim is to explore the inter‐relationship of clinical PVEP and PERG measurements with each other and the optic nerve structure in children investigated for possible optic neuropathies.Methods: ISCEV Standard PVEPs and PERGs to 50′ check widths to large 30 and standard 15 degree fields were reviewed from children suspected to have optic neuropathy of various pathology. Amplitudes and peak times of PERG P50, N95, the N95:P50 amplitude ratio, the amplitude of the N95 from baseline and at 30 ms from the P50‐N95 slope were measured. Spectralis OCT RNFL sector measures and macular ganglion cell volumes were collated.Results: PERG, PVEP with OCT measurements were available for 42 patients, (83 eyes) aged 6‐17 yrs. Those with abnormal PVEPs (33 eyes) had the most severe macular RGC volume loss (mean 0.26 mm3 in 3.45 mm) with mean LogMAR VA 0.52 (range − 0.01 to 1.00). These patients had inherited optic neuropathies, optic neuritis associated with MOGAD and RMMS. In contrast, patients with papilledema, such as associated with IIH, or presenting with headache and reduced vision and full discs had normal PVEPs. Mean VA LogMAR 0.23 (range − 1.0 to 0.9), and mean macular RGC volume 0.45 mm3 in 3.45 mm circle. N95:P50 amplitude ratios ranged from 1.83 to 0.44 in 30 degree fields and 2.16 to 0.36 in 15 degree fields. The N95:P50 amplitude ratios, slope at 30 ms and N95 from baseline correlated with macular RGC volume, but the best PERG discriminator (AUC 0.83) in the large field was the N95 slope measured at 30 ms. RNFL values were confounded by disc oedema in many cases.Conclusions: Pattern reversal VEPs were abnormal in all patients with severe RGC volume loss. The PERG measures correlate with macular RGC volume. RNFL was confounded by disc oedema, but was helpful in highlighting temporal sector thinning in optic neuritis and inherited optic atrophy such as LHOA.

Inline detection of process anomalies during laser deep penetration welding of hidden T-joints

Laser deep penetration welding processes are sensitive towards contaminations inside of the process zone. Automized production facilities report the risk of residual packaging material within the process zone to result in seam defects. These can impair the mechanical properties of the seam and raise the demand for post-process quality control. In-line process monitoring is a promising tool to detect process anomalies correlated to such defects and potentially reduce the demand for time-consuming post-process control. This study investigates the influence of polystyrene particles, a common packaging material, enclosed in the gap of hidden T-joints onto the process dynamics. For process monitoring optical coherence tomography and airborne sound measurement were employed. The provoked process anomalies resulted in increased porosities and significant signal changes of the OCT and airborne sound measurements. This proves the in-line detection capability of process anomalies which occur due to polystyrene particles in joint gaps of hidden T-joints.

Optical coherence tomography ‐ Additional contrast mechanisms, future trends, and cutting‐edge technological developments

In ophthalmology, structural OCT measurements are now used routinely in the clinic to help with the diagnosis and management of anterior‐segment and retinal disorders. More recently, the development of additional or complementary contrast mechanisms, as well as novel approaches targeted at enhancing resolution, have opened up new opportunities for ophthalmic OCT applications. For example, different algorithms have been proposed to contrast the retinal and choroidal vasculature and analyse blood flow, which extend clinical spectral‐domain OCT (SD‐OCT) from structural to functional imaging capabilities. Such OCT‐based angiography (OCT‐A) relies on sequential capture of SD‐OCT images at the same tissue region and the subsequent analysis of temporal variations in the OCT signal. OCT‐A algorithms differ in this analysis, specifically in how they create contrast between flow and static tissue (i.e. how they distinguish vascular from other structures). Common is the assumption that the change in the OCT signal over time is mainly due to the motion of backscattering particles, such as erythrocytes. With so‐called polarization‐sensitive OCT (PS‐OCT), polarized light has also been employed to create tissue‐specific contrast. PS‐OCT has shown great potential for functional and quantitative imaging and exploits the fact that various tissues, particularly birefringent structures in the cornea and retina (e.g. corneal collagen fibrils and the retinal nerve fibre layer), can change the state of polarization of incident light. Other technological developments have focused on enhancing OCT's resolution. Note that while OCT enables high‐resolution cross‐sectional views (where the axial resolution is determined by the spectral bandwidth of the light source), it has a limited lateral or en‐face resolution. Integrating adaptive optics (AO) is one method to improve the lateral resolution of retinal OCT. This lecture will discuss recent technological advances and cutting‐edge developments, leading to additional contrast mechanisms and functional extensions (e.g. OCT‐A, PS‐OCT) or improved lateral resolution (e.g. AO‐OCT).

Correlation between oct measurements and oxidative stress biomarkers in patients with age-related macular degeneration

Correlation between oct measurements and oxidative stress biomarkers in patients with age-related macular degeneration

The association between anterior chamber biometry and posterior capsular defects.

To analyze the association between anterior chamber biometric factors and posterior capsular defects (PCDs) that occur during extracapsular cataract extraction. University Eye Hospital, Goethe University Frankfurt, Germany. Population-based study. Extracapsular cataract extractions for inpatient cases within four years were retrospectively analyzed. The data on the occurrence of PCDs, age, sex, surgeon, and biometry were obtained. For cases with PCDs, the secondary ocular diseases, number of procedures, lens implant, visual acuity, and course were also recorded. Swept-source OCT measurements allowed the measurement of lens thickness (LT) in addition to the usual biometry values. A total of 1967 cataract surgeries (patients age: 70.56 ± 8.42, 1005 women; 962 men) were included, and PCDs were documented for 59 (2.54 %; 31 women, 28 men) cases (patient age: 70.95 ± 8.52 years). There were no differences (p = 0.76) related to the surgeons (n=9) with minimal effect sizes. The mean LT, axial length, corneal curvature, and anterior chamber length were 4950.36 ± 466.63 μm, 23.73 ± 1.77 mm, 43.89 ± 1.36 diopters, and 3.02 ± 0.71 mm, respectively. The Wilcoxon-Mann-Whitney test showed significant associations between LT (p = 0.01) and PCDs with moderate relevance for the Rosenthal effect size (LT R = 0.34; ACD R = 0.29). In addition to ACD, a tendency for the occurrence of PCD could be proven, especially for LT.Therefore, special attention should be paid to LT preoperatively for comprehensive risk stratification.

Automated expert-level scleral spur detection and quantitative biometric analysis on the ANTERION anterior segment OCT system

AimTo perform an independent validation of deep learning (DL) algorithms for automated scleral spur detection and measurement of scleral spur-based biometric parameters in anterior segment optical coherence tomography (AS-OCT) images.MethodsPatients...

GRAPE: A multi-modal dataset of longitudinal follow-up visual field and fundus images for glaucoma management

As one of the leading causes of irreversible blindness worldwide, glaucoma is characterized by structural damage and functional loss. Glaucoma patients often have a long follow-up and prognosis prediction is an important part in treatment. However, existing public glaucoma datasets are almost cross-sectional, concentrating on segmentation on optic disc (OD) and glaucoma diagnosis. With the development of artificial intelligence (AI), the deep learning model can already provide accurate prediction of future visual field (VF) and its progression with the support of longitudinal datasets. Here, we proposed a public longitudinal glaucoma real-world appraisal progression ensemble (GRAPE) dataset. The GRAPE dataset contains 1115 follow-up records from 263 eyes, with VFs, fundus images, OCT measurements and clinical information, and OD segmentation and VF progression are annotated. Two baseline models demonstrated the feasibility in prediction of VF and its progression. This dataset will advance AI research in glaucoma management.

Quantification of scleral changes during dynamic accommodation

The mechanics of accommodation is a complex process that involves multiple intraocular ocular structures. Recent studies suggest that there is deformation of the sclera during accommodation that may also play a role in accommodation, influencing ciliary muscle contraction and contributing to the accommodative response. However, the type and magnitude of the deformations measured varies significantly across studies. We present high-resolution synchronous OCT measurements of the anterior sclera contour and thickness and lens thickness acquired in real-time during accommodative responses to 4D step stimuli. The lens thickness was used as an assessment of objective accommodation. No changes in nasal and temporal anterior scleral contour and scleral thickness were found during accommodation within the precision of our measurements. Our results demonstrate that there are no significant scleral deformations during accommodation.

Pyridostigmine Bromide Pills and Pesticides Exposure as Risk Factors for Eye Disease in Gulf War Veterans.

To examine associations between the pyridostigmine bromide (PB) pill and/or pesticide exposure during the 1990-1991 Gulf War (GW) and eye findings years after deployment. A cross-sectional study of South Florida veterans who were deployed on active duty during the GW Era (GWE). Information on GW exposures and ocular surface symptoms were collected via standardized questionnaires and an ocular surface examination was performed. Participants underwent spectral domain-ocular coherence tomography (SD-OCT) imaging that included retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), and macular maps. We examined for differences in eye findings between individuals exposed versus not exposed to PB pills or pesticides during service. A total of 40.7% (n = 44) of individuals reported exposure to PB pills and 41.7% (n = 45) to pesticides; additionally, 24 reported exposure to both in the GW arena. Demographics were comparable across groups. Individuals exposed to PB pills reported higher dry eye (DE) symptoms scores (the 5-Item Dry Eye Questionnaire, DEQ-5: 9.3 ± 5.3 vs. 7.3 ± 4.7, p = 0.04) and more intense ocular pain (average over the last week: 2.4 ± 2.6 vs. 1.5 ± 1.8, p = 0.03; Neuropathic Pain Symptom Inventory modified for the Eye (NPSI-E): 18.2 ± 20.0 vs. 10.8 ± 13.8, p = 0.03) compared to their non-exposed counterparts. DE signs were comparable between the groups. Individuals exposed to PB pills also had thicker OCT measurements, with the largest difference in the outer temporal segment of the macula (268.5 ± 22.2 μm vs. 260.6 ± 14.5 μm, p = 0.03) compared to non-exposed individuals. These differences remained significant when examined in multivariable models that included demographics and deployment history. Individuals exposed to pesticides had higher neuropathic ocular pain scores (NPSI-E: 17.1 ± 21.1 vs. 11.6 ± 12.9, p = 0.049), but this difference did not remain significant in a multivariable model. Individuals exposed to PB pills during the GWE reported more severe ocular surface symptoms and had thicker OCT measures years after deployment compared to their non-exposed counterparts.

Normative data for macular and retinal nerve fibre layer thickness in healthy German children and adolescents using optical coherence tomography.

To establish normative data for macular thickness, macular volume and peripapillary retinal nerve fibre layer (RNFL) thickness using Spectralis® spectral-domain optical coherence tomography (SD-OCT) in healthy German children and adolescents and investigate influencing factors. The cross-sectional study included the right eye of 695 children with at least one complete retinal OCT scan. As part of the LIFE Child study, the children underwent an ophthalmological examination including axial length (AL), spherical equivalent (SE) and OCT measurements. Various questionnaires were answered by the children or their parents to identify media use or outdoor time. Multiple linear regression models were used to investigate the potential influencing factors. A total of 342 boys and 353 girls with an average age (SD) of 12.91 (3.29) years participated. The mean AL (SD) was 23.20 (0.86)mm. The mean macular thickness (SD) was 320.53 (12.29) μm and the mean RNFL thickness (SD) was 102.88 (8.79)μm. Statistical analysis revealed a significant correlation between average macular thickness and age (p < 0.001, β=0.77) as well as AL (p < 0.001, β=-4.06). In addition, boys had thicker maculae (p < 0.001, β=5.36). The RNFL thickness showed no significant correlation with children's age (p > 0.05), but with AL (p=0.002, β=-2.15), birth weight (p=0.02, β=0.003) and a gender-specific effect of the body mass index standard deviation score for male participants (p=0.02, β=1.93). This study provides normative data and correlations between macular and RNFL thickness in healthy German children. Especially age, gender and AL must be taken into account when evaluating quantitative OCT measurements to classify them as normal.

ANTERIOR SEGMENT OPTICAL COHERENCE TOMOGRAPHY IN DETERMINATION OF ENTRY SITE FOR VITRECTOMY IN HIGHLY MYOPIC EYES.

To evaluate the efficacy of anterior segment optical coherent tomography (AS OCT) in estimating the length of the pars plana and optimizing the sclerotomy entry site in vitrectomy for highly myopic eyes, facilitating membrane peeling. Twenty-three eyes with myopic traction maculopathy were studied. The pars plana was examined using two methods: preoperative AS OCT and intraoperative measurement. The distance from the limbus to the ora serrata in two groups was measured to compare differences in length. The actual length of the entry site from the limbus and forceps used were noted in all eyes studied. The mean axial length was 29.2 ± 2.3 mm for all 23 eyes. The average length between the limbus and ora serrata measured with AS OCT and intraoperative examination was 6,710 µ m (SD ± 459) and 6,671 µ m (SD ± 402), respectively, in the superotemporal region ( P > 0.05), and 6,340 µ m (SD ± 321) and 6,204 µ m (SD ± 402), respectively, in the superonasal region ( P >0.05). The mean length of the entry site from the limbus was 6.2 mm, and 28-mm forceps were used in 17 of 23 eyes (77%). The length of the pars plana varies depending on the axial length of the eye. Preoperative AS OCT enables accurate measurement of the pars plana in eyes with high myopia. AS OCT examination can help determine the optimal site for sclerotomy, allowing easier access to the macular region for membrane peeling in highly myopic eyes.

Characterization of an ablative fractional CO2 laser-induced wound-healing model based on in vitro 3D reconstructed skin.

This study describes the development and characterization of a novel in vitro wound-healing model based on a full-thickness reconstructed skin by exposing the tissue to fractional ablative laser treatment. A 3D full-thickness skin model was fabricated and treated with fractional ablative CO2 laser. Wound-healing process was characterized by HE staining, noninvasive OCT imaging, immunostaining, as well as transepidermal water loss measurement. Cytokines and proteins involved in the inflammatory and dermal remodeling process were studied by ELISA and protein array assays. Fractional ablative CO2 treatment induced a wound zone of 9 mm in diameter, containing 56 micro-wounds with 200 μm diameter and 500-700 μm in depth on reconstructed full-thickness skin model. HE staining revealed a typical wound morphology and healing process with migration of keratinocytes, formation and extrusion of necrotic tissue, and cell inclusion in dermis, which correlates with clinical observations. Based on OCT and TEWL measurements, the re-epithelialization took place over 2 days. Laser-triggered keratinocytes proliferation and differentiation were demonstrated by activated Ki67 and Filaggrin expression respectively. Injury-invoked cytokine ICAM-1 showed instant upregulation on Day 1. Decreased epidermis thickness and depression of IGFBP-2 protein level synergistically indicated the unavoidable thermal side effects from laser treatment. Downregulated DKK-1 protein level and upregulation of α-SMA together implicated the risk of potential fibrosis post-laser treatment. This in vitro laser wounded reconstructed skin model captured the key events of wound-healing process, could be used to investigate the mechanisms of wound-healing triggered by a commonly used beauty procedure, and also provides a valuable tool for evaluating the efficacy of novel actives for the post-procedure application.

A Mechanistic Model of Aqueous Humor Flow to Study Effects of Angle Closure on Intraocular Pressure.

To study the relationship between the circumferential extent of angle closure and elevation in intraocular pressure (IOP) using a novel mechanistic model of aqueous humor (AH) flow. AH flow through conventional and unconventional outflow pathways was modeled using the unified Stokes and Darcy equations, which were solved using the finite element method. The severity and circumferential extent of angle closure were modeled by lowering the permeability of the outflow pathways. The IOP predicted by the model was compared with biometric and IOP data from the Chinese American Eye Study, wherein the circumferential extent of angle closure was determined using anterior segment OCT measurements of angle opening distance. The mechanistic model predicted an initial linear rise in IOP with increasing extent of angle closure which became nonlinear when the extent of closure exceeded around one-half of the circumference. The nonlinear rise in IOP was associated with a nonlinear increase in AH outflow velocity in the open regions of the angle. These predictions were consistent with the nonlinear relationship between angle closure and IOP observed in the clinical data. IOP increases rapidly when the circumferential extent of angle closure exceeds 180°. Residual AH outflow may explain why not all angle closure eyes develop elevated IOP when angle closure is extensive. This study provides insight into the extent of angle closure that is clinically relevant and confers increased risk of elevated IOP. The proposed model can be utilized to study other mechanisms of impaired aqueous outflow.