Anterior Segment Spectral Domain Optical Coherence Tomography Research Articles

Biometric Measurement of Iridocorneal Angle Parameters in a Sample of Healthy Saudi Eyes

Background: Iridocorneal angle (ICA) or anterior chamber angle is the anatomical structure responsible for aqueous humor outflow and regulating intraocular pressure inside the eye. Objective: The study aims to evaluate iridocorneal angle parameters in healthy Saudi eyes using the spectral domain located in the anterior segment optical coherence tomography (AS-OCT) and to describe their correlation with other factors. Methods: For precise measurements of ICA, anterior segment imaging was executed with the aid of spectral-domain AS-OCT MS-39®. The measurements of the iridocorneal angle included angle opening distance (AOD) and trabecular-iris space area (TISA), located 500 and 750 μm away from the actual scleral spur from nasal and temporal angles. Results: The comparison of temporal and nasal angle parameters showed significantly higher AOD500 values in the temporal compared to the nasal angle (p=0.005). The study also evaluated correlations with a grade of the angle, and no correlations were found between gender, refractive error, iris thickness, and angle parameters. Multiple linear regression with backward elimination of non-significant factors found age (p=0.002), angle grade (p<0.001), predicting factors for nasal AOD500 (Adjusted R2=0.772, p<0.001), and angle grade (p<0.001) and temporal iris thickness (p=0.004) predicting factors for temporal AOD500 (Adjusted R2=0.511, p<0.001). IOP (p =0.026) and angle grade (p<0.001) were found to predict factors for nasal TISA500 (Adjusted R2=0.639, p<0.001), and angle grade (p<0.001) and temporal iris thickness was found predicting factors for temporal TISA500 (Adjusted R2=0.314, p<0.001). Conclusion: AS-OCT is a valuable, easy, non-aggressive method to evaluate the iridocorneal angle.

Corneal epithelial thickness mapping by optical coherence tomography in normal and early keratoconic eyes

Background Keratoconus (KC) is a noninflammatory disease causing anatomical deformity of the cornea and is manifested by marked conical protrusion in addition to thinning of the corneal central part. There are currently no standardized screening criteria for KC, making early diagnosis difficult. Early diagnosis aids in stopping progression and better management. It has been proposed that spectral domain optical coherence tomography (SD-OCT) has a diagnostic advantage in the early detection of corneal thickness changes in early KC. Aim Detection of corneal epithelial thickness changes in early KC eyes versus normal eyes using SD-OCT. Methods The research involved 30 eyes with early KC and 30 eyes from healthy control patients. Both groups underwent detailed ophthalmological examination and measurement of regional corneal epithelial thickness with anterior segment SD-OCT. Results In the cases group, corneal epithelium thickness decreased significantly in all regions tested. Additionally, all parameters of the pentacam pachymetry indices showed a statistically significant increase in the cases group. All of the thinnest pachymetry at central 5 mm and 7 mm Area Under the Curve (AUC=0.822 and 0.804), the location Y at central 5 mm and 7 mm (AUC=0.796 and 0.738), the minimum-maximum at central 5 mm and 7 mm (AUC=0.878 and 0.934), and the standard of deviation at central 5 mm and 7 mm (AUC=0.935 and 0.941) showed a statistically significant predictive value for differentiation KC cases from control (P < 0.001), with the highest AUC reported with the standard of deviation. The tested corneal thickness in various regions correlated positively and statistically significantly with pentacam pachymetry indices. Conclusions Early KC is associated with corneal thinning and increased pentacam pachymetry index parameters. The changes detected by pentacam pachymetry and epithelial thickness as detected by SD-OCT showed a significant correlation.

A simple technique for suprachoroidal space injection of triamcinolone acetonide in treatment of macular edema.

To introduce a simple resistance controlled suprachoroidal space (SCS) injection technique using a disposable 30-gauge needle connected to a 1 mL syringe and evaluate the effectiveness and applicability of this technique in the treatment of macular edema. A total of 20 patients with various types of macular edema were subjected to a resistance controlled SCS injection of triamcinolone acetonide (TA) with a disposable 30-gauge needle connected to a 1 mL syringe. This technique allows the easy and smooth injection of the TA only once the tip of the needle reached the potential SCS which was indicated by the lower resistance on the plunger. The main outcome measures were anterior segment spectral-domain optical coherence tomography (AS-OCT) measurements post-operation immediately and central subfield thickness (CST), best-corrected visual acuity (BCVA), and intraocular pressure (IOP) measurements at 3mo post-operation. AS-OCT examination showed the expansion of the SCS near the injection site immediately after SCS injection. At three months of follow-up, as compared to the baseline, the mean CST was significantly decreased from 535.0±157.24 to 319.55±127.30 µm (P<0.001), the mean BCVA was significantly improved from 1.05±0.41 to 0.73±0.41 logMAR (P<0.001), and the mean IOP was not significantly different, from 15.05±2.54 to 15.85±3.60 mm Hg (P=0.185). Any complication related to the injection procedure including cataract, choroidal and retinal hemorrhage, retinal detachment, or endophthalmitis was not observed in this study. The simple and minimally invasive technique of SCS injection of TA with a disposable 30-gauge needle connected to a 1 mL syringe is useful and applicable for macular edema.

Development\ufeff of fully automated anterior chamber cell analysis based on image software

Optical coherence tomography (OCT) is a noninvasive method that can quickly and accurately examine the eye at the cellular level. Several studies have used OCT for analysis of anterior chamber cells. However, these studies have several limitations. This study was performed to supplement existing reports of automated analysis of anterior chamber cell images using spectral domain OCT (SD-OCT) and to compare this method with the Standardization of Uveitis Nomenclature (SUN) grading system. We analyzed 2398 anterior segment SD-OCT images from 34 patients using code written in Python. Cell density, size, and eccentricity were measured automatically. Increases in SUN grade were associated with significant cell density increases at all stages (p < 0.001). Significant differences were observed in eccentricity in uveitis, post-surgical inflammation, and vitreous hemorrhage (p < 0.001). Anterior segment SD-OCT is reliable, fast, and accurate means of anterior chamber cell analysis. This method showed a strong correlation with the SUN grade system. Also, eccentricity could be helpful as a supplementary evaluation tool.

Medical treatment of inflammatory punctual stenosis monitored by anterior segment optical coherence tomography.

To evaluate the role of medical treatment in the management of inflammatory punctum stenosis guided by spectral domain anterior segment optical coherence tomography (OCT). This prospective study included 60 patients complaining of epiphora due to inflammatory punctual stenosis. They were divided into two groups: Group A (30 patients) treated with a combination of preservative free hydrocortisone sodium phosphate 3.35 mg/mL eye drops, and preservative free artificial tears based on sodium hyaluronate, polyethylene and propylene Glycol; Group B (30 patients) treated with the same preservative free artificial tears only. Thirty normal subjects were included for comparison of pre-treatment anatomical parameters. Before starting treatment, all patients underwent anterior segment assessment including slit lamp examination, measurement of intraocular pressure (IOP), fluorescein dye disappearance test, and measurement of the outer punctum diameter (OPD) by Spectral domain anterior segment OCT. All assessments were repeated at each follow up done at 1 and 3mo later, together with subjective evaluation of patient's satisfaction of the treatment outcome by simple rating questionnaire. Punctual diameter increased significantly with treatment in both groups (P<0.0001); although the widening was more in Group A as compared to group B (16.2% vs 8% of the original punctual size, mean difference of 28.933 µm, P=0.0076). Subjective satisfaction with treatment outcome was also better in group A (70% vs 40%, Chi-square P=0.0397). A combination of preservative free steroid eye drops and artificial tears causes significant widening of inflammed stenotic punctae and improvement of the associated epiphora.

Repetitive magnetic stimulation protects corneal epithelium in a rabbit model of short-term exposure keratopathy

PurposeTo investigate the effect of repetitive magnetic stimulation (RMS) on corneal epithelial permeability in a rabbit model of exposure keratopathy. Methods61 female New Zealand White (NZW) rabbits were treated on one eye with repetitive magnetic stimulation (RMS) at a frequency of 20 Hz for 15 min. The other eye was untreated. Rabbit eyes were kept open for 2 h to induce acute corneal desiccation. The extent of fluorescein corneal staining was evaluated using EpiView software and the concentration of fluorescein in the anterior chamber was determined by a fluorometer. Safety was evaluated by electroretinogram, spectral domain optical coherence tomography (SD-OCT) and histopathology. Expression pattern of corneal cell markers was determined by immunofluorescence. ResultsA significant decrease in fluorescein concentration in the anterior chamber (54 ± 8.4 ng/ml vs. 146.5 ± 18.6 ng/ml, p = 0.000001) and in corneal surface fluorescein staining score (1.7 ± 0.2 vs. 4.6 ± 0.6, p = 0.00001) was obtained in RMS-treated eyes compared with control eyes, respectively. RMS treatment reduced by nearly 4 fold the percentage of corneal area with epithelial erosions by anterior segment SD-OCT. The therapeutic effect was maintained for at least 3 months. Increased expression of epithelial tight junction protein Zo-1 was observed in treated eyes. SD-OCT and histopathology analysis revealed no pathological changes in the treated or non-treated eyes. ConclusionsRMS treatment decreases epithelial corneal erosions in a rabbit model of exposure keratopathy, with no indication of pathological changes. RMS may present a novel treatment for protection of corneal epithelium from desiccation.

Characterization of deeply embedded corneal foreign bodies with anterior segment optical coherence tomography.

The purpose of the study was to describe findings demonstrated by anterior segment spectral domain optical coherence tomography (AS-OCT) in various types of deeply embedded corneal foreign bodies. In this experimental study, an ex vivo model of calf eyes was used and seven different foreign bodies were deeply embedded in the cornea, consisting of five different materials: glass, plastic, metal, wood, and pencil graphite. The eyes were photographed and then scanned by AS-OCT. The images were analyzed to determine distinguishing characteristics for each material. Various materials presented unique characteristics in AS-OCT. The opaque materials (pencil graphite, metals, and wood) demonstrated a hyper-reflective anterior border, whereas the posterior border signal could not be clearly identified due to the shadowing effect. Moreover, a chain of signals was characteristic of both pencil graphite and metals though a "mirroring effect" was unique for metals. Wood, as an opaque material, appears as a hyper-reflective mass with a spectrum of penetrability depending on the degree of concentration. Transparent materials demonstrated hyper-reflective sharp borders when surrounded by air or fluid, as opposed to when being embedded purely in the corneal stroma. This study shows that AS-OCT was used to systematically define a novel set of distinguishing characteristics specific to various materials extruding from the cornea, fully embedded in the cornea, and intruding into the anterior chamber. Hopefully, the described characteristics of each material can aid clinicians in diagnosing the type of the material embedded and the depth of its involvement in ocular injury.

Multimodal Assessment of Corneal Erosions Using Optical Coherence Tomography and Automated Grading of Fluorescein Staining in a Rabbit Dry Eye Model.

PurposeTo evaluate the potential use of anterior segment spectral domain optical coherence tomography (AS-SD-OCT) combined with an automated grading of fluorescein staining for assessment of corneal erosions in a rabbit short-term dry eye model.MethodsTwenty-one New Zealand white rabbits were anesthetized and eyes were kept open for 140 minutes to induce acute corneal desiccation. Rectangular scans of the cornea were performed using Spectralis AS-SD-OCT. Total corneal thickness, corneal epithelial thickness, and the percentage of epithelial erosion area (PEEA) were evaluated. Corneas were stained with fluorescein and graded automatically using EpiView and semi-automatically using ImageJ. Spearman's rank-order correlations were calculated to compare the AS-SD-OCT PEEA and the two corneal staining scores.ResultsEye desiccation resulted in corneal epithelium erosions that covered 0.67% to 14.2% of the central cornea (mean ± SD: 3.95% ± 3.2%) by AS-SD-OCT. The percentage of corneal area positively stained with fluorescein ranged from 0.24% to 38.01% (mean ± SD: 12.24% ± 9.7%) by using ImageJ, correlating with the AS-SD-OCT PEEA (Spearman's ρ, 0.574; P = 0.007). The EpiView score ranged from 0.5 to 10.17 and was better correlated with the AS-SD-OCT PEEA score (Spearman's ρ, 0.795; P = 0.000017).ConclusionsOur study suggests that multimodal analysis of AS-SD-OCT and grading of fluorescein staining using EpiView software may enable quantitative assessment of corneal epithelial erosions in a rabbit short-term dry eye model.Translational RelevanceThis multimodal imaging analysis may be applied for evaluation of superficial punctate keratitis associated with dry eye.

Anterior Segment Biometry Using Spectral Domain Optical Coherence Tomography

AbstractBackground: AS-OCT allows a non-contact examination with high resolution imaging of the anterior segment of the eye of human. It enables assessment and documentation of the condition of the eye's anterior segment.Aim of Study: Evaluation of Anterior Segment Optical Coherence Tomography (AS-OCT) in quantitative analysis of the anterior segment of the eye. Analysis of association between Central Corneal Thickness (CCT), Corneal Epithelial Thickness (CET) and corneal radius of curvature (CC) meas-ured by OCT in relation to other parameters; age, sex, refraction and Intra Ocular Pressure (IOP).Patients and Methods: The present study included 100 normal eye of 100 hundred patients aged from 20:60 years. CCT, CET and radius of CC were measured using anterior segment Spectral Domain Optical Coherence Tomography (SD-OCT) (3D OCT-2000 (Topcon Corp., Tokyo, Japan)). IOP was measured using Goldman applanation tonometer. Measurements of refractive status were detected by autore-fractor and then confirmed by retinoscopy and spherical equivalent was calculated of astigmatic patients.Results: Total number of 100 eye were evaluated for the study. 34 eyes were emmetrope, 34 eyes were myopes and 32 eyes were hypermetropics. The CCT average was 541.62mm (SD ±21. 11). This study showed no statistically significant difference between CCT in myopes, hypermetropes and em-metropes). Mean IOP was 15.65mmHg (SD ±1.56). The correlation between IOP and CCT was highly significant (r= 0.867; p<0.001). The CET average was 54.80 (SD ±2.68). The study has shown the positive relation between CET and CCT. The mean radii of corneal curvature was vertically 7.61 (SD ±0.27) and horizontally was 7.61 (SD ±0.25). We found a statistically relation between error of refraction and corneal radius of curvature. Eyes with more myopic refractive error tend to have steeper corneas with less radii of curvature on controversy with hypermetropic eyes. No correlation between age or sex to all the above.Conclusion: This study has shown that CCT has no cor-relation with degree of refractive error. Whereas there is significant correlation between CCT and IOP and CET as well. The study also has shown that there were no associations between corneal radius of curvature and IOP. However, myopic eyes shows tendency for smaller radii of curvature whereas in hypermetropic ones the radii of curvature tend to be longer. There was no significant relation between age and sex and any parameter of the study. Our findings highlight the value of spectral domain AS-OCT measurements as a standard tool in anterior segment analysis.

Spectral Domain Anterior Segment Optical Coherence Tomography in Fungal Keratitis.

To evaluate the use of spectral domain anterior segment optical coherence tomography (SD-ASOCT) in fungal keratitis. Fifty eyes of 50 patients with fungal keratitis were recruited. Serial ASOCT was performed on days 0, 7, 14, 21, 28, 42, and 56. Corneal thickness (CT) in the infiltrate area, infiltrate thickness (IT), and infiltrate width were measured at each follow-up. The presence of any specific feature on ASOCT was evaluated. Mean CT and IT at presentation were 650.5 ± 108 μm and 401.1 ± 91 μm, which reduced significantly at each follow-up [on days 7, 14, 28, and 42; 626.8 ± 113 μm (P < 0.001) and 367.3 ± 94 μm (P = 0.002), 601.4 ± 109 μm and 344.7 ± 94 μm (P < 0.001), 544.8 ± 103 μm and 305.1 ± 80 μm (P < 0.001), and 522.8 ± 97 μm and 291.4 ± 79 μm (P < 0.001), respectively]. The mean CT and scar depth at complete healing were 496.3 ± 101 μm and 283.2 ± 77 μm, respectively. In 10/50 (20%) eyes, the posterior border of the cornea was not clearly visible because of posterior shadowing; therefore, IT was measured along the maximum visible area of hyperreflectivity, whereas CT was measured just adjacent to the area of shadowing. The infiltrate width was measured in 35 eyes, and the mean values at days 0, 7, 14, 28, 42, and 56 were 5.5 ± 0.8 mm, 4.6 ± 0.7 mm, 4.4 ± 0.6 mm, 4.2 ± 0.6 mm, 4.1 ± 0.6 mm, and 4.1 ± 0.6 mm, respectively. A satellite lesion and endothelial plaque were seen in 30% (15/50) and 44% (22/50) eyes, respectively. ASOCT is a useful adjunct in monitoring fungal keratitis especially in cases with deep stromal involvement and endothelial plaques. In addition, it also provides insight into the activity of keratitis.

Tear meniscus evaluation after microkeratome laser in situ keratomileusis, femtosecond laser and femtosmile laser techniques using anterior segment optical coherence tomography.

PurposeThe purpose of this study was to compare the effects of three different corneal refractive surgeries: microkeratome laser in situ keratomileusis (LASIK), femtosecond laser in situ keratomileusis (FS-LASIK) and femtosecond small incision lenticule extraction (FS-SMILE) on 6-month postoperative stability of tear film to provide a basis for selection of operative procedures.Patients and methodsThis is a prospective, randomized, comparative study that included 90 eyes of three equal groups of patients. Each group was subjected to a different laser technique: LASIK, FS-LASIK and FS-SMILE. Using anterior segment spectral domain optical coherence tomography (AS-SD-OCT), the lower tear meniscus parameters were measured preoperatively and 1 week, 1 month, 3 months and 6 months postoperatively. Changes were studied and compared.ResultsThere was a statistically significant difference in tear meniscus height (TMH) between FS-SMILE and FS-LASIK in the first week (P = 0.003) and first month (P = 0.002) with no statistically significant difference between both techniques at 3 and 6 months postoperatively. In FS-SMILE, TMH returned to 95% of its preoperative level after 1 month. There was no statistically significant difference in TMH between FS-LASIK and microkeratome LASIK techniques after 1 week and 1 month, but there was a statistically significant difference between both techniques in 3 months (P = 0.019) and 6 months (P = 0.032). Tear meniscus area (TMA) showed no statistically significant difference between FS-SMILE and FS-LASIK at all points of follow-up, but there was a statistically significant difference between both techniques and microkeratome LASIK (all P < 0.05). Microkeratome LASIK parameters failed to reach the preoperative level till 6 months.ConclusionEarly recovery of the lower TMH can be achieved as early as 1 month post-operatively with the FS-SMILE technique compared to FS-LASIK and microkeratome LASIK techniques.

Epithelial remodeling after corneal crosslinking using higher fluence and accelerated treatment time

To evaluate changes in regional corneal epithelial thickness after corneal crosslinking (CXL) using higher fluence (7.2J/cm2) and accelerated treatment time (4minutes) in eyes with progressive keratoconus using spectral-domain optical coherence tomography (SD-OCT) and to correlate focal epithelial and focal anterior curvature changes. Academic medical center in the United States. Prospective case series. Patients had anterior segment SD-OCT (RTVue-100) with focal stromal and epithelial measurements and Scheimpflug imaging before and 1, 3, 6, and 12months after accelerated CXL. Twenty-seven eyes from 20 patients were evaluated. Before the accelerated CXL, the epithelium was thinnest in the inferior inner and outer temporal regions, whereas at 12months postoperatively, the epithelium was significantly thinned in multiple inferior and nasal regions by 1.1 to 3.2μm(P<.05, all measurements), with no significant changes from 6 to 12months. Epithelial thickness standard deviation across the central 6.0mm was significantly reduced by 3months (1.4μm, P=.09) and remained stable at 12months (P=.009). Change in epithelial thickness was poorly correlated to change in anterior curvature (r=-0.035). Significant epithelial remodeling occurred after accelerated CXL in eyes with progressive keratoconus, with improved regularity across the central 6.0mm, by 6months aftertreatment. There was poor correlation between focal epithelial thickness and anterior curvature changes, with wide variability between patients. Establishing the pattern of epithelial remodeling after CXL might help optimize future custom treatment protocols.

Age- and sex-related differences in corneal epithelial thickness measured with spectral domain anterior segment optical coherence tomography among Egyptians.

Is to measure the corneal epithelial thickness (CET) in a group of healthy Egyptian population and to investigate its variation with age and sex using spectral domain-anterior segment optical coherence tomography (SD-AS-OCT).This cross-sectional observational study includes 240 eyes of 120 healthy individuals (60 men, 60 women). Each gender was divided into 4 equal groups according to age as follows (18–29 years), (30–44 years), (45–59 years), and (60–80 years). The CET in 17 points over a corneal diameter of 6.0 mm was measured in each subject by SD-AS-OCT. The regional thickness changes were compared in different age groups of each gender separately and the correlations between the CET, age, and gender were analyzed.The CET of the central cornea (2 mm), the paracentral and the midperipheral zones (2–5 and 5–6 mm, respectively) of all males and females groups demonstrates highly significant changes with age (P < .001) with no significant difference between males and females. The measured parameters in the 2 age groups below 45 and above 45 years old revealed statistically significant difference with lower values in the elderly group (P < .001).The CET became thinner with age in the central, paracentral, and midperipheral zones in both genders and there is no difference between males and females. These findings could be valuable in refractive surgeries especially in age over 45.

Automated circumferential construction of first-order aqueous humor outflow pathways using spectral-domain optical coherence tomography.

The purpose was to create a three-dimensional (3-D) model of circumferential aqueous humor outflow (AHO) in a living human eye with an automated detection algorithm for Schlemm’s canal (SC) and first-order collector channels (CC) applied to spectral-domain optical coherence tomography (SD-OCT). Anterior segment SD-OCT scans from a subject were acquired circumferentially around the limbus. A Bayesian Ridge method was used to approximate the location of the SC on infrared confocal laser scanning ophthalmoscopic images with a cross multiplication tool developed to initiate SC/CC detection automated through a fuzzy hidden Markov Chain approach. Automatic segmentation of SC and initial CC’s was manually confirmed by two masked graders. Outflow pathways detected by the segmentation algorithm were reconstructed into a 3-D representation of AHO. Overall, only <1% of images (5114 total B-scans) were ungradable. Automatic segmentation algorithm performed well with SC detection 98.3% of the time and <0.1% false positive detection compared to expert grader consensus. CC was detected 84.2% of the time with 1.4% false positive detection. 3-D representation of AHO pathways demonstrated variably thicker and thinner SC with some clear CC roots. Circumferential (360 deg), automated, and validated AHO detection of angle structures in the living human eye with reconstruction was possible.

Epithelial Thickness Profile Changes Following Small Incision Refractive Lenticule Extraction (SMILE) for Myopia and Myopic Astigmatism.

To evaluate the epithelial thickness profile changes following small incision refractive lenticule extraction (SMILE) and study their correlation with the amount of myopia corrected. Epithelial thickness was measured in nine zones with spectral-domain anterior segment optical coherence tomography (SD-OCT) across a 6-mm diameter preoperatively and at 1 day, 2 weeks, and 3 months postoperatively. The observed changes were correlated with the degree of myopia corrected. The study included 100 eyes from 50 eligible patients (32 females, 18 males) with a mean age of 24.4 ± 2.8 years. Thirty-eight eyes underwent SMILE for low (spherical equivalent [SE] < -4.00 diopters [D]), 44 eyes for moderate (SE -4.00 to -6.00 D), and 18 eyes for high (SE > -6.00 to -10.00 D) myopia with 6.71 ± 1.65, 6.82 ± 0.21, and 6.44 ± 0.2 mm optical zones, respectively. At 3 months, a statistically significant epithelial thickness increase was observed in the central zone (6.83% for low, 9.26% for moderate, and 12.7% for high myopia, P < .05 for all groups) and superior zone (3.98% for low, 7.82% for moderate, and 9.87% for high myopia) across all three groups, which correlated positively with the degree of myopia corrected (r(2) = 0.723 for central zone, r(2) = 0.585 for superior zone, P < .001 for both zones). None of the other zones showed any statistically significant changes at 3 months. Four eyes of two patients with high myopia (SE > -8.00 D) had regression due to significant epithelial thickening. Preliminary results suggest that epithelial thickness profile changes after SMILE may have an impact on the refractive outcome in the long-term postoperative period, especially in higher degrees of myopia. [J Refract Surg. 2016;32(7):473-478.].

Comparison of ultrasound biomicroscopy and spectral-domain anterior segment optical coherence tomography in evaluation of anterior segment after laser peripheral iridotomy.

To quantitatively assess narrow anterior chamber angle using spectral-domain anterior segment optical coherence tomography (SD-AS-OCT) and ultrasound biomicroscopy (UBM), and to evaluate the correlations and consistency between SD-AS-OCT and UBM. Fifty-five eyes from 40 patients were examined. Patients were diagnosed with primary angle-closure glaucoma (PACG) remission (11 eyes from 8 patients), primary angle closure (PAC, 20 eyes from 20 patients) and PAC suspect (24 eyes from 12 patients). Each eye was examined by SD-AS-OCT and UBM after laser peripheral iridotomy (LPI). The measurements of SD-AS-OCT were angle open distance (AOD), anterior chamber angle (ACA), trabecular iris angle (TIA), and trabecular iris space area (TISA). UBM measurements were AOD and TIA. Correlations of AOD500 and TIA500 between UBM and AS-OCT were assessed. All parameters were analysed by SPSS 16.0 and MedCalc. ACA, TIA and AOD measured by SD-AS-OCT reached a maximum at the temporal quadrant and minimum at the nasal quadrant. TISA reached the maximum at the inferior and minimum at the superior quadrant. Group parameters of AOD500 and AOD750 showed a linear positive correlation, and AOD750 had less variability. UBM outcomes of AOD500 and TIA500 were significantly smaller than those of SD-AS-OCT. The results of the two techniques were correlated at the superior, nasal and inferior quadrants. Both UBM and SD-AS-OCT are efficient tools for follow-up during the course of PACG. We recommended using parameters at 750 µm anterior to the sclera spur for the screening and follow-up of PACG and PAC. The two methods might be alternatives to each other.

Spectral Domain Anterior Segment Optical Coherence Tomography in Microbial Keratitis

Purpose: To investigate the spectral domain anterior segment optical coherence tomography (SDAS-OCT) parameters in microbial keratitis. Design: Prospective, cross-sectional, observational study. Methods: Thirty eyes of 30 patients with proven microbial keratitis (fungal, bacterial and viral), at different stages of the disease, underwent SDAS-OCT imaging. Results 12 eyes were diagnosed with proven fungal keratitis, 10 eyes with proven bacterial keratitis and 8 eyes with proven of viral keratitis. Different types of SDAS- OCT presentations of microbial keratitis were found in this study. Conclusion: SDAS-OCT imaging provided a range of characteristic patterns that could be used as an additional tool in management and assessing the response to treatment of microbial keratitis.

Assessment of corneal layers thickness with spectral‐domain optical coherence tomography

PurposeTo assess the corneal layers thickness in healthy young adults using spectral‐domain anterior segment optical coherence tomography (AS‐OCT).MethodsThere were 86 eyes of 86 healthy volunteers, 55 females and 31 males, which were included in the study. The mean age ± standard deviation (SD) was 22.87 ± 3.90 years (range, 20–43). Spectral‐domain AS‐OCT was performed using Spectralis OCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany). Measurements of central corneal thickness, and central thickness of epithelium, Bowman's layer, stroma and the complex Descemet‐endothelium were performed.ResultsMean central corneal thickness, epithelium, Bowman, stroma and Descemet‐endothelium were 555.50 ± 29.64 µm (range 510–624), 54.60 ± 4.25 µm (range 45–63), 16.70 ± 1.73 µm (range 14–20), 467.51 ± 28.91 µm (range 420–533) and 16.74 ± 1.66 µm (range 14–20), respectively.ConclusionsSpectralis OCT can be easily used to non‐invasive measurements of the anterior segment parameters and this study establishes a normal database for corneal thickness and all its layers in healthy young adults.

Descemet membrane endothelial keratoplasty: intraoperative and postoperative imaging spectral-domain optical coherence tomography.

We describe a case report of using the same handheld spectral-domain anterior segment optical coherence tomography (ASOCT) for rapid intraoperative and postoperative imaging in a case of Descemet membrane endothelial keratoplasty (DMEK). A 67-year-old woman, with Fuchs dystrophy and corneal decompensation, underwent DMEK with intraoperative ASOCT imaging using the handheld Envisu spectral domain ASOCT system (Bioptigen, Inc., Morrisville, NC, USA). We found that this easy-to-use portable system with handheld probe allowed for rapid imaging of the anterior segment during donor manipulation to visualize the orientation of the DMEK donor, as well as to confirm the initial adhesion of the DMEK donor. Moreover, the same system may be used for postoperative monitoring of graft adhesion, corneal thickness, and stromal remodeling in the clinic with very high-definition images.

Corneal epithelial remodeling following cataract surgery: three-dimensional investigation with anterior-segment optical coherence tomography.

To map corneal and epithelial layer thickness changes following cataract removal surgery employing a spectral-domain anterior-segment optical coherence tomography system. Corneal and epithelial thickness three-dimensional profile distribution was clinically imaged preoperatively and up to 3 months postoperatively with anterior-segment optical coherence tomography in 116 consecutive cases. Descriptive statistics investigated central corneal thickness, minimum corneal thickness, and epithelial thickness at the central 2-mm area, the mean over the 6-mm area, and mid-peripherally at 5-mm ring. In comparison to preoperative, the center, mean, and mid-peripheral epithelial thickness at the first postoperative day increased by +2.84, +2.35, and +2.25 μm, respectively (P < .001, < .001, and = .0014). One week postoperatively, the epithelial thickness differences were -1.91, -2.62, and -2.76 μm, respectively (P < .001, < .001, and < .001). Four weeks postoperatively, the differences of -0.20, -0.59, and -0.66 μm for the center, mean, and mid-periphery were not statistically significant (P = .6449, .1512, and .11097). Three months postoperatively, the differences were -0.05, -0.28, and -0.09 μm, respectively (P = .8722, .2341, and .6431). Qualitative and quantitative assessment of epithelial remodeling following cataract removal indicated that the early (1 day and 1 week) corneal and epithelial thickness returned to the preoperative baseline 4 weeks postoperatively. This in vivo epithelial and corneal screening with optical coherence tomography can be valuable for the postoperative assessment and follow-up.