Domain Optical Coherence Tomography Devices Research Articles

Optical Coherence Tomography in Schizophrenia Spectrum Disorders: A Systematic Review and Meta-analysis

BackgroundInner retinal atrophy has been demonstrated in schizophrenia spectrum disorder (SSD) using optical coherence tomography (OCT). This systematic review and meta-analysis investigated the role of contemporary Fourier domain OCT devices in SSD. MethodsMEDLINE, PubMed, Scopus, Embase, PsycInfo, PYSNDEX, World Health Organization, and Cochrane databases were searched from inception until May 2022. All peer-reviewed adult SSD case-control studies using Fourier domain OCT were included. Ocular pathologies known to affect retinal OCT scans were excluded. Search, data appraisal, and summary data extraction were independently performed by 2 authors. ResultsThe review criteria was met by k = 36 studies, with k = 24 studies (1074 cases, 854 controls) suitable for meta-analysis. The SSD group exhibited a thinner global peripapillary retinal nerve fiber layer (−3.26 μm, 95% CI, −5.07 to −1.45, I2 = 64%, k = 21), thinner average macular layer (−7.88 μm, 95% CI, −12.73 to −3.04, I2 = 65%, k = 11), and thinner macular ganglion cell-inner plexiform sublayer (−2.44 μm, 95% CI, −4.13 to −0.76, I2 = 30%, k = 8) compared with the control group. Retinal nerve fiber layer findings remained significant after exclusion of metabolic disease, low quality, outlier, and influential studies. Studies involving eye examinations to exclude eye disease were associated with greater atrophy in SSD. Except for cardiometabolic disease, most studies did not report clinically significant covariate data known to influence retinal thickness. ConclusionsIndividuals with SSD generally exhibited retinal atrophy, possibly paralleling reduced brain volumes documented in clinical imaging. Prospective longitudinal studies that collect clinical data, including various illness phases, and control for confounders will be necessary to evaluate retinal atrophy as a biomarker in SSD.

EVALUATION OF PERIPAPILLARY RETINAL NERVE FIBRE LAYER AND CENTRAL MACULAR THICKNESS INADULTS WITH HYPEROPIC ANISOMETROPIC AMBLYOPIA

Objective: To study per-papillary retinal nerve fibre layer (pRNFL) and central macular thickness (CMT) changesin adults with hyperopic anisometropic amblyopia using optical coherence tomography.
 Study Design: Cross sectional study.
 Place and Duration of Study: Combined Military Hospital, Lahore, Pakistan, from Oct 2019 to Feb 2020.
 Methodology: In this study 30 adults, 18-40 years of age were included who presented in our clinic with monocular poor vision. They underwent detailed ophthalmic clinical examination: including corrected and uncorrected distance visual acuity, slit lamp bio-microscopy and fundus examination with 90 diopter lens. After fulfilling criteria of anisometropic amblyopia, central maular thickness (CMT) and per-papillary retinal nerve fibre layer (pRNFL) thickness was measured by using RS-3000 SLO, NIDEK Co, Japan spectral domain optical coherence tomography device and compared the central maular thickness (CMT) and per-papillary retinal nerve fibre layer (pRNFL) thickness in amblyopic and fellow eye of same individual.
 Results: The mean change in per-papillary retinal nerve fibre layer (pRNFL) thickness in amblyopic eyes, 121.48± 4.90 μm and non amblyopic eyes was 112.92 ± 4.72 μm with statistical significance (p<0.001). The mean change in central macular thickness (CMT) in amblyopic eyes was 198.50 ± 5.30 μm and non amblyopic eyes was 206.80 ± 3.11 μm with statistical significance (p<0.001). There was significant increase in per-papillary retinal nerve fibre layer (pRNFL) thickness and significant decrease in central macular thickness (CMT) on comparing the amblyopic and the fellow eyes of the same patients.
 Conclusion: Central macular thickness (CMT) decreased.........................

COMPARISON OF GANGLION CELL INNER PLEXIFORM LAYER THICKNESS BY CIRRUS AND SPECTRALIS OPTICAL COHERENCE TOMOGRAPHY IN DIABETIC MACULAR EDEMA.

Reduced thickness of the ganglion cell inner plexiform layer indicates diabetic neurodegeneration and can be assessed by spectral domain optical coherence tomography. The authors investigated the comparability of ganglion cell inner plexiform layer measurements from two spectral domain optical coherence tomography devices in patients with diabetic macular edema (DME). Analysis of optical coherence tomography data sets of eyes with and fellow eyes without DME. Macular cube scans of sufficient signal strength on Cirrus (Carl Zeiss Meditec) were compared with correlating scans on Spectralis (Heidelberg Engineering, Germany) being acquired within 1 hour. Eighty-one equivalent data sets for 20 eyes with DME (20 patients; 6 female) and 33 for 9 fellow eyes without DME (9 patients; 2 female) were included from each device. In DME eyes, mean ganglion cell inner plexiform layer thicknesses were 62.5 ± 20.4 μm on Cirrus and 91.2 ± 9.3 μm on Spectralis. Ganglion cell inner plexiform layer was significantly thicker on Spectralis analyzing eyes with and without signs of DME (P < 0.001). The ganglion cell inner plexiform layer variance (54.2%) related to device differences decreased to 34.8% in eyes without DME. Ganglion cell inner plexiform layer data from different devices vary considerably and cannot be used interchangeably. As spectral domain optical coherence tomography is indispensable for identifying ganglion cell loss associated with diabetic neurodegeneration, clinicians should be aware of the difference when monitoring patients.

CHOROIDAL THICKNESS IN INFANTS WITH RETINOPATHY OF PREMATURITY.

To evaluate choroidal thickness in premature infants and its relationship with stage of retinopathy of prematurity (ROP) using spectral domain optical coherence tomography (SD-OCT). Spectral domain optical coherence tomography imaging for measuring subfoveal choroidal thickness was performed for 80 premature infants. Subfoveal choroidal thickness was defined as the distance from the hyperreflective line of the outermost retinal pigment epithelium (RPE) to the innermost hyperreflective line of the choroidoscleral junction. Each measurement was performed at the central fovea (CF) and 0.75 mm to 1.5 mm nasal (N1 and N2) and temporal (T1 and T2) to the fovea. Subfoveal choroidal thickness and grading of cystoid macular edema (CME) were analyzed statistically. Choroidal thickness of CF was found to be significantly greater than nasal (N1 and N2) and temporal (T1 and T2) choroidal thickness (P < 0.05). There was no significant relationship between stage of ROP and nasal (N1 and N2) choroidal thickness (P = 0.057, P = 0.282, respectively). However, CF and temporal (T1 and T2) choroidal thickness was found to be significantly lower at a higher stage of ROP (P = 0.005, P = 0.01 and P = 0.001). No significant relationship was found between subfoveal choroidal thickness and the grades of cystoid macular edema (P > 0.05). The choroidal thickness of CF was found to be correlated with birth weight (r = 0.267, P = 0.017) but not birth week (r = 0.140, P = 0.217). Maximum stage of ROP was found to be negatively correlated with choroidal thickness, at N1, T1, and T2 (r < -0.250, P < 0.02). The subfoveal choroid in premature infants can be effectively evaluated using a portable SD-OCT device. Choroidal thickness gets thinner with the severity of ROP and the decrease is more prominent at the central and temporal location. Cystoid macular edema is not correlated with choroidal thickness in premature infants.

Intra-Operative Cap Repositioning in Small Incision Lenticule Extraction (SMILE) for Enhanced Visual Recovery

ABSTRACTPurpose: To study the role of intra-operative cap repositioning in acute visual recovery after small incision lenticule extraction (SMILE).Materials and methods: Ninety-four eyes of 47 patients underwent the SMILE procedure for correction of myopic refractive error. Manifest refraction and visual quality parameters (optical quality analysis system) were evaluated before surgery. The Bowman’s membrane was imaged using a handheld spectral domain optical coherence tomography device. All patients underwent an uneventful SMILE surgery by a single experienced surgeon. Intra-operative cap repositioning was done in the “right” eye of all patients (repositioned group) and the “left” eye of each patient served as controls (non-repositioned group). Visual acuity and optical quality were assessed 1 day and 1 week after surgery.Results: Bowman’s membrane microdistortions were found in 21.3% of eyes in the repositioned group and 59.57% of the eyes in the non-repositioned group (p = 0.003) on the first day after surgery. Comparison of optical quality parameters was carried out between eyes where repositioning was done and control eyes (with and without microdistortions). On the first day after surgery, the modulation transfer function (MTF) and Strehl’s ratio (SR) were significantly better in the repositioned group when compared with the controls (p = 0.002 and p = 0.003, respectively). Refractive error and lenticule thickness in eyes with microdistortions were similar (p > 0.05) between the two groups indicating other contributors to acute optical quality postoperatively.Conclusions: Although the refractive error before surgery determines the extent of microdistortions, intra-operative cap repositioning can reduce them, thereby expediting acute visual recovery after SMILE.

Topiramate-Induced Changes in Anterior Chamber Angle and Choroidal Thickness.

To investigate the acute effects of topiramate on the anterior chamber angle (ACA) and choroidal thickness in patients with migraine. This prospective study included 15 eyes of 15 patients with migraine who have been scheduled to start topiramate therapy. All patients underwent complete ophthalmic examination including measurement of the ACA and choroidal thickness using a spectral domain optical coherence tomography device (Optovue Inc.) and refractive status evaluation with an autorefractokeratometer (KR-8100; Topcon) at the baseline and 1 week after starting therapy. The patients were asked to report any pain or discomfort in their eyes during therapy at the follow-up visit. None of the patients experienced pain or discomfort in their eyes. The mean ACA significantly decreased at the first week of the therapy compared with the baseline levels (40.34±7.06° and 36.89±6.87°, respectively) (P=0.001). However, the mean choroidal thickness increased from 277.33±95.60 μm at the baseline to 323.40±84.50 μm at the first week (P=0.01). There was a nonsignificant increase in the mean refractive error (from -0.25±0.54 diopter [D] at the baseline to -0.38±0.49 D after 1 week) (P=0.06). Topiramate can acutely decrease the ACA and increase the choroidal thickness. Because these effects may be asymptomatic, patients with migraine who start this therapy should be warned to be closely followed up by an ophthalmologist.

Retinal Nerve Fiber Layer Thickness Measured with Two Different Spectral Domain Optical Coherence Tomography Devices

Purpose: To assess the agreement and compare the performance of glaucoma diagnosis of peripapillary retinal nerve fiber layer (RNFL) thickness measurements between two different spectral-domain optical coherence tomography (SD-OCT) devices. Methods: Eighty nine eyes of 56 patients with glaucoma and 42 eyes of 25 healthy individuals were imaged with Cirrus and Spectralis OCT in a single visit. Agreement between RNFL thickness measurements was assessed using intraclass coefficient (ICC) and Bland-Altman plots. The discriminating abilities of the two techniques for detection of glaucoma were compared by the area under the receiver operating characteristic curves (AUC) for quadrants and average RNFL thickness. Results: ICC values for agreement between both instruments were good for quadrants and average RNFL thickness (all ≥ 0.81). However, Spectralis OCT measurements were significantly greater than Cirrus OCT for temporal quadrant (difference = 4.27 μm in normal group, 3.91 μm in glaucoma group, p < 0.001 for both). The RNFL thickness parameter with the largest AUCs was the average RNFL thickness for the Spectralis OCT and the Cirrus OCT (0.85 vs. 0.87, p = 0.30). The pair-wise comparison among the receiver operating characteristic curves showed no statistical difference for all parameters. Conclusions: Although Spectralis OCT measurements were significantly greater than Cirrus OCT for temporal quadrant, agreement of RNFL measurement between both the devices was generally good and there was no statistically significant difference in the performance of glaucoma diagnosis between both instruments. J Korean Ophthalmol Soc 2016;57(7):1118-1125

RETINAL AND CHOROIDAL VASCULATURE IN BIRDSHOT CHORIORETINOPATHY ANALYZED USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To describe retinal and choroidal vascular changes in eyes with birdshot chorioretinopathy using optical coherence tomography angiography. Patients underwent imaging using the AngioVue prototype software of the RTVue XR spectral domain optical coherence tomography device (Optovue, Inc) between September and December 2014. Two trained patients evaluated the optical coherence tomography angiography images for changes in the retinal and choroidal vasculature in the posterior pole. Four of eight eyes (50%) had birdshot lesions in the posterior pole as demonstrated on fundus photography. All of these eyes demonstrated the areas of decreased choroidal blood flow below the disrupted retinal pigment epithelium. Larger choroidal vessels bordered the birdshot lesions. All eyes analyzed showed retinal thinning, telangiectatic vessels, and an increased intercapillary space. Capillary dilatations and loops were each seen in 7 of 8 eyes (88%). Optical coherence tomography angiography provides precise microvascular detail of the retinal vasculature and choriocapillaris that allows for the noninvasive visualization of the birdshot lesions and changes in the inner retina. The optical coherence tomography angiography images delineated widespread retinal vascular findings not previously described in the literature. In the future, optical coherence tomography angiography could be a useful tool to evaluate the natural history of birdshot chorioretinopathy, its progression, and the effect of treatment in these patients.

Age-related changes in the anterior segment biometry during accommodation.

We investigated the dynamic response of human accommodative elements as a function of age during accommodation using synchronized spectral domain optical coherence tomography devices (SD-OCT). We enrolled 33 left eyes from 33 healthy subjects (age range, 20-39 years, 17 males and 16 females). Two SD-OCT devices were synchronized to simultaneously image the anterior segment through pupil and the ciliary muscle during 6.00 diopter (D) accommodation for approximately 3.7 seconds in two repeated measurements. The anterior segment parameters included the lens thickness (LT), radius of curvature of the lens anterior surface (LAC), maximum thickness of ciliary muscle (CMTMAX), and anterior length of the ciliary muscle (CMAL). A first-order exponential equation was used to fit the dynamic changes during accommodation. The age-related changes in the dynamic response and their relationship were calculated and compared. The amplitude (r = -0.40 and 0.53 for LT and LAC, respectively) and peak velocity (r = -0.65 and 0.71 for LT and LAC, respectively) of the changes in LT and LAC significantly decreased with age (P < 0.05), whereas the parameters of the ciliary muscle remained unchanged (P > 0.05), except for the peak velocity of the CMAL (r = 0.44, P = 0.01). The difference in the time constant between the lens reshaping (LT and LAC) and CMTMAX increased with age (r = 0.46 and 0.57 for LT and LAC, respectively, P < 0.01). The changes in LT and LAC per millimeter of CMTMAX change decreased with age (r = -0.52 and -0.34, respectively, P < 0.05). The ciliary muscle forward movement correlated with the lens deformation (r = -0.35 and 0.40 for amplitude, while r = 0.36 and 0.58 for time constant, respectively, P < 0.05). Age-related changes in the lens reshaping and ciliary muscle forward movement were found. Lens reshaping was much slower than the contraction of the ciliary muscle, especially in aging eyes, and this process required the ciliary muscle to contract more to reach a given response.

Retinal Nerve Fibre Layer and Macular Thicknesses in Adults with Hyperopic Anisometropic Amblyopia.

Objectives. This study compared the macular and retinal nerve fibre layer (RNFL) thicknesses and optic nerves of eyes with reduced vision due to anisometropia with the contralateral healthy eyes in adults using optical coherence tomography (OCT). Methods. This cross-sectional study was conducted in Atatürk State Hospital, Sinop, Turkey. Macular and RNFL thicknesses, optic nerve disc area, cup area, and horizontal and vertical cup-to-disc ratios obtained using a NIDEK RS-3000 SLO spectral domain OCT device were compared between the amblyopic and fellow eyes in 30 adults with anisometropic amblyopia 18–55 years old who were seen in our clinic with unilateral poor vision. Results. The mean macular thickness was 266.90 ± 23.22 µm in the amblyopic eyes and 263.90 ± 22.84 µm in the fellow eyes, and the mean RNFL thickness was 111.90 ± 12.9 and 109.70 ± 9.42 µm, respectively. The two thicknesses did not differ significantly between the amblyopic and fellow eyes. There were also no significant differences between the eyes in disc area, cup area, and horizontal-vertical cup/disc ratios. Conclusion. There does not seem to be a difference in macular thickness, peripapillary RNFL, or optic disc structures between the amblyopic and fellow eyes in adults.

Choroidal thickness in relation to sex, age, refractive error, and axial length in healthy Turkish subjects.

The aim of this study was to investigate the association between choroidal thickness (CT) and sex, age, refractive error (RE), and axial length in healthy subjects. This is a study of 154 eyes in 154 healthy subjects. CT measurements were performed by the same experienced technician using a spectral domain optical coherence tomography device. CT was measured perpendicularly from the outer edge of the retinal pigment epithelium to the choroid-sclera boundary at the fovea and at six more points which are located at, respectively, 500 µm nasal to the fovea, 1,000 µm nasal to the fovea, and 1,500 μm nasal to the fovea, 500 μm temporal to the fovea, 1,000 μm temporal to the fovea, and 1,500 μm temporal to the fovea. The RE was measured by autorefractometry, and the axial length was measured by interferometry. Statistical analysis was performed to evaluate CT at each location, and to the correlations of CT with sex, age, RE, and axial length. The mean subfoveal CT was 265.86 ± 60.32 µm, the mean age was 49.01 ± 19.19 years, the mean RE was -0.17 ± 1.20 diopters (D), and the mean axial length was 23.39 ± 0.76 mm. CT profile indicated that the choroid was thicker at the fovea than at temporal and nasal locations. Univariable linear regression analysis showed that subfoveal CT decreased 3.14 µm for each year of age and decreased 79.33 µm for each mm of axial length (P = 0.000, R(2) = 0.249; P = 0.000, R(2) = 0.487, respectively). In a similar analysis, subfoveal CT was found to decrease by 50.24 µm/D myopia-shifted change in refraction (P = 0.000, R (2) = 0.201). The subfoveal choroid was 99.16 µm (39.22 %) thicker in men than women when adjusting for age and axial length (P = 0.000, R(2) = 0.249). CT decreases with increasing myopia, age, and axial length. Men had thicker choroid than women, and CT varies depending on location.

Photoreceptor outer segment layer thickness measured manually on images from spectral domain optical coherence tomography in healthy volunteers

To investigate photoreceptor outer segment layer thickness measured with a manual technique on images from spectral domain optical coherence tomography (OCT) in healthy volunteers. In 60 eyes of 30 healthy volunteers, a spectral domain OCT device (Spectralis, Heidelberg Engineering) was used to obtain cross-sectional images of the retina. For each volunteer, two images of each eye were obtained in one sitting. Images were digitally enlarged and the manual calipers feature of the device's software was used to measure, at the lowest point in the fovea, the thickness of the photoreceptor outer segment layer. All measurements were performed by the same investigator. Repeatability was evaluated with the Bland-Altman repeatability coefficient, and intersubject variability with Pearson's coefficient of variation. The mean values of measurements across all the volunteers were as follows: right eye first image 38.1 micrometers, right eye second image 37.9 micrometers, left eye first image 37.9 micrometers, left eye second image 37.9 micrometers. The repeatability coefficient, i.e. the difference between repeated measurements which would be exceeded in only 5% of cases, was 1.6 micrometers. Coefficients of variation for the right eye were 3.4% for the first images and 3.4% for the second images, and for the left eye they were 3.2 and 4.0% respectively. With a manual method based on spectral domain OCT, the thickness of the photoreceptor outer segment layer at the central fovea can be measured within a useful range of repeatability and appears to be relatively constant across healthy volunteers.

Development in anterior segment imaging for glaucoma

Recent developments in anterior segment imaging enable high-resolution imaging with higher speeds than previous systems. This review will focus on advances in optical coherence tomography (OCT) imaging of the anterior segment with an emphasis on angle evaluation. Anterior segment imaging with OCT is possible with both time domain and Fourier domain devices, and with light sources of different wavelengths. Recent studies have identified new risk factors for angle closure and prediction models incorporating quantitative angle width parameters have been developed for detection of gonioscopically defined angle closure. Swept source OCT is a variation of Fourier domain OCT that allows three-dimensional imaging of the angle analogous to gonioscopy and novel quantitative parameters have been described for angle measurement with this technology. Fourier domain OCT devices have higher resolution and sampling density than time domain OCT and enable visualization of more angle structures such as the Schwalbe's line and Schlemm's canal. OCT technology is expanding our understanding of angle closure disease. Although it does not replace gonioscopy in angle evaluation, it may help us identify predictors of progression along the angle closure disease spectrum such that treatment may be better targeted.

Pathology detection rate of spectral domain optical coherence tomography devices

BackgroundSpectral domain optical coherence tomography (SDOCT) allows for higher resolution scans and higher scanning speeds compared to time domain OCT (TDOCT). The purpose of this study is to compare the...

OPTICAL COHERENCE TOMOGRAPHY–BASED CORRELATION BETWEEN CHOROIDAL THICKNESS AND DRUSEN LOAD IN DRY AGE-RELATED MACULAR DEGENERATION

Spectral domain optical coherence tomography can be used to measure both choroidal thickness and drusen load. The authors conducted an exploratory study using spectral domain optical coherence tomography to determine if a correlation between choroidal thickness and drusen load exists in patients with dry age-related macular degeneration. Forty-four patients with dry age-related macular degeneration were recruited. The drusen area and volume were determined using the automated software algorithm of the spectral domain optical coherence tomography device, and choroidal thickness was measured using enhanced depth imaging. Correlations were determined using multivariable and univariable analyses. The authors found an inverse correlation between choroidal thickness and drusen load (r = -0.35, P = 0.04). Drusen load was also correlated with visual acuity (r = 0.32, P = 0.04). A correlation between choroidal thickness and visual acuity was suggested (r = -0.22, P = 0.21). Spectral domain optical coherence tomography can be used to assess the correlation between drusen load and choroidal thickness, both of which show a relationship with visual acuity. The measurement of these outcomes may serve as important outcome parameters in routine clinical care and in clinical trials for patients with dry age-related macular degeneration.

Comparison of two different spectral domain optical coherence tomography devices in the detection of localized retinal nerve fiber layer defects

To compare the detection of localized retinal nerve fiber layer (RNFL) defects by two different spectral domain optical coherence tomography (SD-OCT) devices. Eyes of 42 normal control subjects and 48 patients with a localized RNFL defect on red-free fundus photographs were imaged by the Cirrus (Carl Zeiss Meditec, Dublin, CA, USA) and 3D OCT (Topcon, Tokyo, Japan) devices. We compared sensitivities, specificities, and area under the receiver operating characteristic curves (AUCs) of circumpapillary RNFL (cpRNFL) thickness and ganglion cell complex (GCC) parameters between the two devices. The devices provided different cpRNFL thickness measurements. The highest sensitivities at fixed specificities of 80 % (Cirrus: 83.3 %; 3D OCT: 77.1 %) and 95 % (Cirrus: 69.8 %; 3D OCT: 68.8 %) and the largest AUCs (Cirrus: 0.90; 3D OCT: 0.88) obtained by the cpRNFL parameters of the two devices were similar. Based on the internal normative database, the deviation-from-normal map of the Cirrus OCT device and the 36-segment map of the 3D OCT device had the highest sensitivity (89.6 and 91.7 %, respectively). Among the macular GCC parameters of the 3D OCT device, inferior macular RNFL thickness had the highest sensitivity (81.2 % at a specificity of 80 %) and the largest AUC (0.89). Although the two SD-OCT devices have different measurement protocols, they showed similar abilities for the detection of a localized RNFL defect.

Simultaneous real-time imaging of the ocular anterior segment including the ciliary muscle during accommodation

We demonstrated a novel approach of imaging the anterior segment including the ciliary muscle using combined and synchronized two spectral domain optical coherence tomography devices (SD-OCT). In one SD-OCT, a Complementary Metal-Oxide-Semiconductor Transistor (CMOS) camera and an alternating reference arm was used to image the anterior segment from the cornea to the lens. Another SD-OCT for imaging the ciliary muscle was equipped with a light source with a center wavelength of 1,310 nm and a bandwidth of 75 nm. Repeated measurements were performed under relaxed and 4.00 D accommodative stimulus states in six eyes from 6 subjects. We also imaged dynamic changes in the anterior segment in one eye during accommodation. The biometry of the anterior segment and the ciliary muscle was obtained. The combined system appeared to be capable to simultaneously real-time image the biometry of the anterior segment, including the ciliary muscle, in vivo during accommodation.

Comparison of Two Spectral Domain Optical Coherence Tomography Devices for Angle-Closure Assessment

To compare two spectral domain optical coherence tomography (SD-OCT) devices for the identification of angle structures and the presence of angle closure. This was a prospective comparative study. Consecutive patients underwent gonioscopy and anterior segment imaging using two SD-OCT devices (iVue and Cirrus). Images were evaluated for the ability to detect angle structures such as Schwalbe's line (SL), trabecular meshwork (TM), Schlemm's canal (SC), and scleral spur (SS), and the presence of angle closure. Angle closure was defined as iris contact with the angle wall anterior to the SS on SD-OCT, and nonvisibility of the posterior TM on gonioscopy. Angle closure in an eye was defined as ≥two quadrants of closed angles. AC1 statistic was used to assess the agreement between devices. Of the 69 subjects studied (46.4% male, 84.1% Chinese, mean age 64.0 ± 10.5 years), 40 subjects (40 eyes, 58.0%) had angle closure on gonioscopy. The most identifiable structure on Cirrus SD-OCT was the SS (82.2%) and SL on iVue SD-OCT (74.5%). Angle closure was indeterminable in 14.5% and 50.7% of Cirrus and iVue scans (P < 0.001), respectively. Interdevice agreement for angle closure was moderately strong (AC1 = 0.67), but agreement with gonioscopy was only fair (AC1 = 0.35 and 0.50 for Cirrus and iVue, respectively). It was more difficult to determine angle closure status with iVue compared with Cirrus SD-OCT. There was fair agreement between both devices with gonioscopy for identifying angle closure.

Signal Quality Assessment of Retinal Optical Coherence Tomography Images

The purpose of this article was to assess signal quality of retinal optical coherence tomography (OCT) images from multiple devices using subjective and quantitative measurements. A total of 120 multiframe OCT images from 4 spectral domain OCT devices (Cirrus, RTVue, Spectralis, and 3D OCT-1000) were evaluated subjectively by trained graders, and measured quantitatively using a derived parameter, maximum tissue contrast index (mTCI). An intensity histogram decomposition model was proposed to separate the foreground and background information of OCT images and to calculate the mTCI. The mTCI results were compared with the manufacturer signal index (MSI) provided by the respective devices, and to the subjective grading scores (SGS). Statistically significant correlations were observed between the paired methods (i.e., SGS and MSI, SGS and mTCI, and mTCI and MSI). Fisher's Z transformation indicated the Pearson correlation coefficient ρ ≥ 0.8 for all devices. Using the Deming regression, correlation parameters between the paired methods were established. This allowed conversion from the proprietary MSI values to SGS and mTCI that are universally applied to each device. The study suggests signal quality of retinal OCT images can be evaluated subjectively and objectively, independent of the devices. Together with the proposed histogram decomposition model, mTCI may be used as a standardization metric for OCT signal quality that would affect measurements.

Macular thickness measurements in macular hole using Fourier domain optical coherence tomography devices

Abstract Purpose To compare new Fourier‐domain optical coherence tomographies (OCT) for measuring retinal thickness in eyes with macular hole (MH). Methods Thirty‐eight eyes from 38 patients diagnosed of MH (17 men and 21 women, aged 51‐ 82 years) without other ophthalmic diseases, were prospective and consecutively studied. All of them underwent a ophthalmic examination including best corrected visual acuity, fundus examination, three Cirrus HD‐OCT (Carl Zeiss Meditec, Inc., Ca, USA) and three Spectralis OCT (Heidelberg Engineering, Germany). Comparisons of OCT measurements were done for the nine macular areas defined by the Early Treatment Diabetic Retinopathy Study (ETDRS). Correlations between OCT measures were studied by Pearson test. Results Mean total retinal thicknesses were 347.0 ± 67.78 μm using Cirrus HD and 344.71 ± 43.63 μm with Spectralis OCT. All retinal measurements showed significant differences between the two devices (p&lt;0.05), except in superior and nasal inner ETDRS area. The mean value for retinal thickness measurements was 21.44 µm less using Cirrus HD‐OCT. Cirrus and Spectralis OCT parameters showed good correlations. Conclusion MH eyes evaluated by Cirrus and Spectralis OCT show differences in their macular measurements.