IOL Calculation using the ESCRS Online Calculator in Pediatric Eyes Undergoing Lens Extraction.

PURPOSE: To evaluate the ESCRS online calculator for intraocular lens (IOL) calculation in children undergoing lens extraction and primary IOL implantation. SETTING: Department of Ophthalmology, Goethe University Frankfurt, Germany. DESIGN: Retrospective, consecutive case series. METHODS: We included eyes that received phacoemulsification and IOL implantation (Acrysof SN60AT, Alcon, Fort Worth, Tx, USA) due to congenital or juvenile cataract. We compared the mean prediction error (MPE), mean and median absolute prediction error (MAE, MedAE) of formulas provided by the recently introduced online calculator provided by the European Society of Cataract and Refractive Surgeons (ESCRS) to the SRK/T formula, as well as the number of eyes within ±0.5, ±1.0, ±2.0 diopters (D) of target refraction. Postoperative spherical equivalent was measured by retinoscopy 4 to 12 weeks after surgery. RESULTS: Sixty eyes from forty-seven patients with a mean age of 6.5 years ± 3.2 met the inclusion criteria. Mean axial length was 22.27mm ± 1.19. Mean preoperative spherical equivalent (SE) was -0.25 D ± 3.78 and mean postoperative SE was 0.69 D ± 1.53. The MedAE was lowest in the SRK/T formula (0.56 D, ± 1.03) performed significantly better (p = 0.037) than Hoffer QST and Kane, followed by BUII (0.64D, ± 0.92), Pearl DGS (0.65D, ± 0.94), EVO (0.69D, ± 0.94), Hoffer QST (0.75D, ± 0.99), and Kane (0.78D, ± 0.99). All of those were significantly above zero (p < 0.001). Forty-one eyes received an intraoperative optic capture (68%). When excluding eyes that did not receive intraoperative optic capture (n=19; 32%) the MedAE was shown to be lower. CONCLUSION: Using modern IOL calculation formulas provided by the ESCRS calculator provides good refractive predictability and compares for most of the formulas to the results with SRK/T. Additionally the formulas seem to anticipate the postoperative refraction better for eyes that receive a posterior optic capture.

The impact of perinatal brain injury on retinal nerve fiber layer thickness and optic nerve head parameters of premature children.

PURPOSE: This study aims to evaluate the impact of birth weight (BW), gestational age (GA), retinopathy of prematurity (ROP), and perinatal brain injury (PBI) on optic nerve head (ONH) parameters and nerve fiber layer thickness (RNFLT) in preterm children. METHODS: ONH parameters and RNFLT were examined prospectively in 5-15-year-old preterm and full-term children with RTVue-100 OCT (Optovue, USA). The parameters of the two groups were compared and possible influences of BW, GA, ROP, and PBI analyzed in preterm children. RESULTS: In total, 51 full-term and 55 preterm children were included. The mean age was 9.98 ± 3.4 years in full-term and 10.0 ± 2.5 years in preterm children. The mean GA in preterm children was 29.6 ± 3.8 weeks with a BW of 1523 ± 732 g. RNFLT was significantly lower in preterm than in full-term children in all but temporal quadrants. Cup area, volume, cup/disc area ratio, and horizontal cup/disc ratio (CDR) were significantly larger and rim area significantly thinner in preterm children. GA was positively correlated with superior, nasal, and overall RNFLT and negatively correlated with cup area, volume, and horizontal CDR. ROP stage correlated negatively with superior and nasal RNFLT. PBI was the only significant predicting factor for RNFL thinning in all but temporal quadrant in multiple regression analysis. Preterm children with PBI had a significantly larger optic cup (CDR 0.70 ± 0.33 vs. 0.37 ± 0.27) and thinner optic rim. CONCLUSION: PBI correlated strongest with RNFL thinning, a thinner optic rim, and a larger optic cup in preterm children and should be evaluated in each patient to prevent incorrect diagnosis like glaucoma.

Ophthalmic artery occlusion after glabellar hyaluronic acid filler injection.

PURPOSE: Filler injections for aesthetic purposes are very popular, but can have far-reaching and irreversible consequences. This report describes the course of a patient with devastating complications after glabellar hyaluronic acid injection, their pathomechanism, management and outcome. OBSERVATIONS: A healthy, 43-year-old woman underwent her first hyaluronic acid injection in the glabella and went blind on her left eye immediately thereafter. Massaging of the injection area and observation were performed, before she presented with swelling of the left forehead and upper lid, ptosis, complete ophthalmoplegia and blindness in our hospital. Immediate massaging of the globe and systemic therapy including acetylsalicylic acid, tinzaparin sodium and cortisone was initiated and hyaluronidase injections in the injection area were performed. In the further course, the patient developed necrotic and hemorrhagic skin and mucosal lesions, lagophthalmos, anterior and posterior segment ischemia and globe hypotonia with consecutive globe deformation. In the follow-up of 2.5 months, lid swelling, lagophthalmos and ptosis resolved and keratopathy improved but blindness, skin lesions and strabismus with reduced eye motility were still present and madarosis and early enophthalmos were detected. CONCLUSIONS AND IMPORTANCE: The outcome of ophthalmic artery occlusion after hyaluronic acid filler injection is poor. Sufficient knowledge about facial anatomy, the implementation of filler injections and the management of complications is essential for the practitioner. The patient should be clarified about potential and even rare risks of these procedures.

Electronically monitored occlusion therapy in amblyopia with eccentric fixation.

PURPOSE: Amblyopia with eccentric fixation, especially when not diagnosed early, is a therapeutic challenge, as visual outcome is known to be poorer than in amblyopia with central fixation. Consequently, treatment after late diagnosis is often denied. Electronic monitoring of occlusion provides us the chance to gain first focussed insight into age-dependent dose response and treatment efficiency, as well as the shift of fixation in this rare group of paediatric patients. METHODS: In our prospective pilot study, we examined amblyopes with eccentric fixation during 12 months of occlusion treatment. We evaluated their visual acuity, recorded patching duration using a TheraMon®-microsensor, and determined their fixation with a direct ophthalmoscope. Dose-response relationship and treatment efficiency were calculated. RESULTS: The study included 12 participants with strabismic and combined amblyopia aged 2.9-12.4 years (mean 6.5). Median prescription of occlusion was 7.7 h/day (range 6.6-9.9) and median daily received occlusion was 5.2 h/day (range 0.7-9.7). At study end, median acuity gain was 0.6 log units (range 0-1.6) and residual interocular visual acuity difference (IOVAD) 0.3 log units (range 0-1.8). There was neither significant acuity gain nor reduction in IOVAD after the 6th month of treatment. Children younger than 4 years showed best response with lowest residual IOVAD at study end. Efficiency calculation showed an acuity gain of approximately one line from 100 h of patching in the first 2 months and half a line after 6 months. There was a significant decline of treatment efficiency with age (p = 0.01). Foveolar fixation was achieved after median 3 months (range 1-6). Three patients (> 6 years) did not gain central fixation. CONCLUSION: Eccentric fixation is a challenge to therapy success. Based on electronic monitoring, our study quantified for the first time the reduction of treatment efficiency with increasing age in amblyopes with eccentric fixation. Despite some improvement in patients up to 8 years, older patients showed significantly lower treatment efficiency. In younger patients with good adherence, despite poor initial acuity, central fixation and low residual IOVAD could be attained after median 3 months. Hence, the necessity of early diagnosis and intensive occlusion should be emphasized.

Posterior continuous curvilinear capsulorhexis with anterior vitrectomy vs optic capture buttonholing without anterior vitrectomy in pediatric cataract surgery.

PURPOSE: To investigate long-term complications after pediatric cataract surgery with implantation of a heparin-coated polymethyl methacrylate intraocular lens (PMMA IOL) and posterior continuous curvilinear capsulorhexis (PCCC) with anterior vitrectomy vs PCCC without anterior vitrectomy with optic capture buttonholing. SETTING: Department of Ophthalmology, Goethe University, Frankfurt, Germany. DESIGN: Prospective randomized clinical trial. METHODS: Eyes with unilateral or bilateral congenital cataract without further pathologies or former surgeries were randomly assigned in 2 groups: cataract removal, IOL implantation, and PCCC with anterior vitrectomy (group A) or posterior optic buttonholing without anterior vitrectomy (group B). The main outcome measures were posterior capsule opacification (PCO), complication rates, and refractive development. RESULTS: 58 eyes of 41 pediatric cataract surgery patients were included. The mean age at the time of operation was 66.05 months (±29.39). In group A (n = 26), 2 eyes required treatment for PCO, whereas the optic axis remained clear in all eyes in group B (n = 30), which was statistically insignificant. In addition, group B had a slightly lower rate of complications. The mean spherical equivalent after a mean postoperative follow-up of 6.5 years was -0.11 ± 2.51 diopters (D) (-5.0 to +4.0 D) in group A and -0.08 ± 2.14 D (-5.0 to +4.0 D) in group B, which was also statistically insignificant. CONCLUSIONS: Optic capture with a heparin-coated PMMA IOL proved to be a safe technique in the prevention of secondary cataract formation without a higher rate of complications and the necessity of vitrectomy.

Digital and Technical Developments in the Amblyopia Therapy. / Digitale und technische Entwicklungen in der Amblyopietherapie.

The digital media becomes more and more common in our everyday lives. So it is not surprising that technical progress is also leaving its mark on amblyopia therapy. New media and technologies can be used both in the actual amblyopia therapy or therapy monitoring. In particular in this review shutter glasses, therapy monitoring and analysis using microsensors and newer video programs for amblyopia therapy are presented and critically discussed. Currently, these cannot yet replace classic amblyopia therapy. They represent interesting options that will occupy us even more in the future.

Revisiting the Safety of the Corneal Collagen Crosslinking Procedure: Evaluation of the Effect of Ultraviolet A Radiation on Retinal Function and Structure.

PURPOSE: To evaluate the effect of ultraviolet A radiation on retinal function and structure after the corneal collagen crosslinking procedure. METHODS: In the present prospective, single-center cohort study 17 eyes of 17 patients who underwent collagen crosslinking (Dresden protocol) for the treatment of corneal ectasia were examined preoperatively and at 2 and 6 weeks postoperatively with multifocal electroretinogram and optical coherence tomography. The P1 amplitude density (P1-AD) of the central retinal response was documented in 5 concentric rings, with ring 1 (R1) representing the foveal response and rings 2 to 5 (R2-R5) corresponding to successive annuli of stimulation. Visual acuity, corneal densitometry at the 0 to 2 mm zone and at the 2 to 6 mm annulus, and macular thickness (MT; central, 1 mm, 3 mm, and 5 mm zones) were recorded. RESULTS: The preoperative values of P1-AD were R1 = 109.96 ± 28.96, R2 = 49.8 ± 14.46, R3 = 29.85 ± 8.9, R4 = 19.33 ± 6.3, and R5 = 16.39 ± 5.48 nV/deg. At 2 weeks, these values were R1 = 77.54 ± 24.47, R2 = 36.55 ± 12.53, R3 = 21.53 ± 7.71, R4 = 15.3 ± 6.13, and R5 = 13.32 ± 5.48, showing a significant reduction for R1-R4 (P ≤ 0.026). The 6-week P1-AD was R1 = 99.8 ± 31.23, R2 = 40.67 ± 16.39, R3 = 24.98 ± 7.13, R4 = 16.35 ± 4.84, and R5 = 13.76 ± 3.98, showing no significant differences compared with preoperative values (P ≥ 0.054). Corneal densitometry increased significantly at 2 weeks (P < 0.001) and remained increased at 6 weeks (P < 0.001), showing statistically insignificant correlations with 2-week P1-AD (P ≥ 0.553). The central MT increased (P = 0.787), whereas MT at 1 mm (P = 0.444), 3 mm (P = 0.039), and 5 mm (P < 0.001) zones decreased. CONCLUSIONS: The return of P1-AD to preoperative (physiologic) values at 6 weeks confirms the safety standards of the duration and intensity of ultraviolet A radiation, as proposed by the Dresden protocol. However, temporary postoperative retinal dysfunction cannot be excluded.

Assessment of stereovision with digital testing in adults and children with normal and impaired binocularity.

New digital approaches allow stereovision to be assessed with greater precision than current clinical stereo tests. Those current tests present a relatively narrow range of stimulus disparities in coarsely quantized steps. With dichoptic treatments for amblyopia emerging, more accurate assessment of especially coarse stereopsis becomes increasingly important for verifying their aim to improve 3D vision. We used digital testing in subjects of a large age range (4-59 years), with groups having both normal (n = 34) and impaired binocular vision due to unilateral amblyopia, with or without strabismus (n = 27). Random-dot stimuli were presented on a 3D monitor with shutter glasses. The test applies adaptive procedures to measure psychometric functions and provides thresholds with associated confidence intervals. Digital thresholds for controls (range 11-160 arcsec) and stereodeficient subjects (range 43-911 arcsec) were compared to the TNO, a standard clinical test which uses similar random-dot targets presented with anaglyph glasses. Agreement between digital and TNO thresholds varied with the level of stereopsis. Stereoacuity was measurable in several subjects who failed on the TNO. With the digital test we found good repeatability for both groups, with the indication of a small learning effect for subjects with coarse stereopsis. Thus, assessment of all target groups for new tests is important, and repeated testing before therapy may avoid confusing learning and treatment effects. Our digital approach supplies a large range of accurate stereo data in children and adults; together with its associated measure of variability, it will be useful in longitudinal treatment studies.

Comparison of Optic Disc Parameters in Hyperopic and Emmetropic Eyes of Healthy Children with HRT and OCT.

PURPOSE: To investigate, through Heidelberg retina tomography II (HRT II) and RTVue-100 optical coherence tomography (OCT), normal parameters of the optic nerve head (ONH) in highly hyperopic children, and compare these with a group of children with low hyperopia and emmetropia, as fundus examination of highly hyperopic children often shows crowding of the optic disc, which may be difficult to distinguish from mild optic disc swelling. PATIENTS AND METHODS: ONH of the higher hyperopic eye was examined with HRT II and the peripapillary nerve fiber layer (RNFL) with RTVue-100, in 6 to 15-year-old full-term children with normal visual acuity and spherical equivalent ≥ + 3.0 D (hyperopic group) and < + 3.0 to - 1.0 D (emmetropic group). RESULTS: Thirty highly hyperopic children and 33 emmetropic controls had a mean spherical equivalent of + 5.1 ± 1.5 D and a mean age of 8.4 ± 2.8 years, and + 1.0 ± 1.2 D and 9.6 ± 2.6 years, respectively. There was no significant difference in OCT-assessed RNFL thickness between the two groups. Compared to the emmetropic group, following HRT parameters were significantly smaller in the hyperopic group: Disc area (1.41 vs. 1.68 mm2, p = 0.023), cup area (0.19 vs. 0.37 mm2, p = 0.0001), cup volume (0.03 vs. 0.08 mm3, p = 0.02), cup/disc area (0.13 vs. 0.20, p = 0.006), linear cup/disc (0.33 vs. 0.42, p = 0.004), and mean cup depth (0.13 vs. 0.17 mm, p = 0.019). CONCLUSION: In children, ONH of highly hyperopic eyes are smaller than those of emmetropic eyes. RNFL thickness and neural rim volume are similar to emmetropic eyes. They can therefore appear more crowded.

Congenital cataract surgery without intraocular lens implantation in persistent fetal vasculature syndrome: Long-term clinical and functional results.

PURPOSE: To evaluate long-term clinical and functional outcomes after congenital cataract surgery in persistent fetal vasculature (PFV). SETTING: Department of Ophthalmology, Goethe-University, Frankfurt, Germany. DESIGN: Retrospective comparative case series. METHODS: The records of eyes with congenital cataract associated or not associated with PFV that had cataract surgery without intraocular lens (IOL) implantation within the first 18 months of life were reviewed. Long-term visual outcomes and clinical parameters, including aphakic glaucoma, posterior capsule opacification (PCO), vitreous and anterior segment hemorrhage, retinal detachment (RD), and fibrin reaction, were evaluated. RESULTS: Congenital cataract was associated with PFV in 19 eyes (19 children) and not associated in 69 eyes (40 children). Sixteen patients had isolated anterior PFV; 3 eyes were classified as combined anterior and posterior PFV. The mean follow-up was 53.21 months. Postoperative visual acuity improvement was recorded in 68.4% of PFV-associated cataract eyes with a corrected visual acuity up to 20/100. Long-term visual outcomes in PFV-associated cataract eyes were significantly worse than in the 11 unilateral cataract eyes without additional PFV (P = .0067). The presence of PFV was strongly associated with a long-term increased risk for postoperative hemorrhage (P = .0001) and RD (P = .009) after primary cataract surgery and secondary IOL implantation. The prevalence of aphakic glaucoma, PCO, and fibrinous reaction was similar between PFV cataract eyes and controls. CONCLUSIONS: In most cases of PFV-associated congenital cataract, postoperative visual acuity improvement is possible. However, congenital cataract eyes associated with PFV have a long-term increased risk for postoperative hemorrhage and RD. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Optical Coherence Tomography (OCT) Device Independent Intraretinal Layer Segmentation.

PURPOSE: To develop and test an algorithm to segment intraretinal layers irrespectively of the actual Optical Coherence Tomography (OCT) device used. METHODS: The developed algorithm is based on the graph theory optimization. The algorithm's performance was evaluated against that of three expert graders for unsigned boundary position difference and thickness measurement of a retinal layer group in 50 and 41 B-scans, respectively. Reproducibility of the algorithm was tested in 30 C-scans of 10 healthy subjects each with the Spectralis and the Stratus OCT. Comparability between different devices was evaluated in 84 C-scans (volume or radial scans) obtained from 21 healthy subjects, two scans per subject with the Spectralis OCT, and one scan per subject each with the Stratus OCT and the RTVue-100 OCT. Each C-scan was segmented and the mean thickness for each retinal layer in sections of the early treatment of diabetic retinopathy study (ETDRS) grid was measured. RESULTS: The algorithm was able to segment up to 11 intraretinal layers. Measurements with the algorithm were within the 95% confidence interval of a single grader and the difference was smaller than the interindividual difference between the expert graders themselves. The cross-device examination of ETDRS-grid related layer thicknesses highly agreed between the three OCT devices. The algorithm correctly segmented a C-scan of a patient with X-linked retinitis pigmentosa. CONCLUSIONS: The segmentation software provides device-independent, reliable, and reproducible analysis of intraretinal layers, similar to what is obtained from expert graders. TRANSLATIONAL RELEVANCE: Potential application of the software includes routine clinical practice and multicenter clinical trials.

Visual evoked potential-based acuity assessment: overestimation in amblyopia.

BACKGROUND/AIMS: When visual acuity (VA) is assessed with spatially repetitive stimuli (e.g., gratings) in amblyopes, VA can be markedly overestimated. We evaluated to what extent this also applies to VEP-based objective acuity assessment, which typically uses gratings or checkerboards. METHODS: Seventeen subjects with amblyopia (anisometropic and strabismic) participated in the study; decimal VA range of their amblyopic eye covered 0.03-1.0 (1.5-0.0 logMAR). Using the Freiburg Acuity VEP (FrAVEP) method, checkerboard stimuli with six check sizes covering 0.02°-0.4° were presented in brief-onset mode (40 ms on, 93 ms off) at 7.5 Hz. All VEPs were recorded with a Laplacian montage. Fourier analysis yielded the amplitude and significance at the stimulus frequency. Psychophysical VA was assessed with the Landolt-C-based automated Freiburg Visual Acuity Test (FrACT). RESULTS: Test-retest limits of agreement for both FrACT and FrAVEP were ±0.20 logMAR. In all but two dominant eyes and high-acuity amblyopic eyes (VA<0.3 logMAR), FrACT and FrAVEP agreed within the expected limits of ±0.3 logMAR. However, the VEP-based acuity procedure overestimated single Landolt-C acuity by more than 0.3 logMAR in 9 of 17 (53%) of the amblyopic eyes, up to 1 logMAR. While all subjects had a psychophysical acuity difference>0.2 logMAR between the dominant and amblyopic eye, only three of them showed such difference with the FrAVEP. CONCLUSION: Both measurements of visual acuity with the VEP and FrACT were highly reproducible. However, as expected, in amblyopia, acuity can be markedly overestimated using the VEP. We attribute this to the use of repetitive stimulus patterns (checkerboards), which also lead to overestimation in psychophysical measures. The VEP-based objective assessment never underestimated visual acuity, but needs to be interpreted with appropriate caution in amblyopia.

Normative values of peripheral retinal thickness measured with Spectralis OCT in healthy young adults.

BACKGROUND: To evaluate the range of peripheral retinal thickness (PRT) in young healthy human subjects by Spectralis HRA + OCT, and to analyze a potential association between the peripheral location, spherical equivalent (SE), axial length (AL), and gender. METHODS: After pupil dilation, the peripheral retina was scanned by means of six volume protocols (9 × 7.5 mm), each consisting of 31 B-scans. PRT was determined at 4,500, 5,500, 6,500 and 7,500 µm eccentricity from the fovea and the optic nerve head (ONH). Data points were collected every 22.5°. Six additional data points at a distance of 9,000 µm were included. In 11 subjects, OCT measurements were performed twice to evaluate reproducibility. Coefficients of variation (COV) were calculated. RESULTS: Randomly selected eyes of 50 subjects (19-30 years) with AL of 21-27 mm (SE: -5.75 to +5.25 dpt) were included in the study. Mean PRT decreased significantly (p ≤ 0.001, r = -0.99) towards the periphery, reaching a minimum at 9,000 µm eccentricity (mean PRT: 187.7 ± 8.9 µm). Multiple regression analysis revealed a significant association of PRT with AL at nasal and temporal locations as well as gender for temporal locations. COVs ranged from 0.44 to 2.90 %, with highest COVs found nasal to the fovea. CONCLUSIONS: This is the first study to report normative data of PRT outside the ETDRS grid and to show a significant continuous almost linear decrease of the RT from the center into the periphery. The data will be valuable to detect peripheral pathologies of the retina in early stages of peripheral retinal dystrophies.

Fibrinolysis in normal vitreous liquid.

Plasmin is the key enzyme of fibrinolysis. Plasmin-alpha2-antiplasmin (PAP) complexes are biomarkers of fibrinolysis activation. The purpose of our investigation was to evaluate the activity of fibrinolysis in normal human eyes, that is in eyes without blood-retina barrier breakdown (BRB), which has not been investigated so far. Twenty-two vitreal samples were harvested at the beginning of a standard 23-gauge three-port pars plana vitrectomy for macular pucker removal, macular hole closure or vitreal floater removal from the central vitreous body. These samples were immediately stabilized with human albumin (2.5% final conc.) and arginine (1.25 mmol/l final conc.) and subsequently frozen. Plasminogen was functionally determined in an ultra-sensitive pNA reaction after activation with streptokinase (100% = functional plasminogen in pooled normal citrated plasma). PAP concentrations were measured by enzyme immune assay (EIA). Intravitreal functional plasminogen exhibited to be 1 ±â€Š0.65% (range: 0.2-2.49%). PAP concentrations ranged at levels of 14 ±â€Š9ng/ml (range: 2-33 ng/ml). Pearson's correlation quotient between functional plasminogen and PAP revealed to be r equal to -0.27 (P = 0.221). No adverse events or serious side effects occurred. Sampling vitreous fluid at the beginning of a standard 23-gauge three-port pars plana vitrectomy is a well tolerated procedure. A strict stabilization procedure for extracted vitreous specimen is necessary to obtain activities and concentrations that are close to the true intraocular value. There is a basal intraocular fibrinolysis, a possible target for intravitreal pharmacological therapy.

Automated segmentation of pathological cavities in optical coherence tomography scans.

PURPOSE: To develop and evaluate a method for automated segmentation and quantitative analysis of pathological cavities in the retina visualized by spectral-domain optical coherence tomography (SD-OCT) scans. METHODS: The algorithm is based on the segmentation of the gray-level intensities within a B-scan by a k-means cluster analysis and subsequent classification by a k-nearest neighbor algorithm. Accuracy was evaluated against three clinical experts using 130 bullous cavities identified on eight SD-OCT B-scans of three patients with wet age-related macular degeneration (AMD) and five patients with X-linked retinoschisis, as well as on one volume scan of a patient with X-linked retinoschisis. The algorithm calculated the surface area of the cavities for the B-scans and the volume of all cavities for the volume scan. In order to validate the applicability of the algorithm in clinical use, we analyzed 31 volume scans taken over the course of 4 years for one AMD patient with a serous retinal detachment. RESULTS: Discrepancies in area measurements between the segmentation results of the algorithm and the experts were within the range of the area deviations among the experts. Volumes interpolated from the B-scan series of the volume scan were comparable among experts and algorithm (0.249 mm³ for the algorithm, 0.271 mm³ for expert 1, 0.239 mm³ for expert 2, and 0.262 mm³ for expert 3). Volume changes of the serous retinal detachment were quantifiable. CONCLUSIONS: The segmentation algorithm represents a method for the automated analysis of large numbers of volume scans during routine diagnostics and in clinical trials.

Automated segmentation of retinal blood vessels in spectral domain optical coherence tomography scans.

The correct segmentation of blood vessels in optical coherence tomography (OCT) images may be an important requirement for the analysis of intra-retinal layer thickness in human retinal diseases. We developed a shape model based procedure for the automatic segmentation of retinal blood vessels in spectral domain (SD)-OCT scans acquired with the Spectralis OCT system. The segmentation procedure is based on a statistical shape model that has been created through manual segmentation of vessels in a training phase. The actual segmentation procedure is performed after the approximate vessel position has been defined by a shadowgraph that assigns the lateral vessel positions. The active shape model method is subsequently used to segment blood vessel contours in axial direction. The automated segmentation results were validated against the manual segmentation of the same vessels by three expert readers. Manual and automated segmentations of 168 blood vessels from 34 B-scans were analyzed with respect to the deviations in the mean Euclidean distance and surface area. The mean Euclidean distance between the automatically and manually segmented contours (on average 4.0 pixels respectively 20 µm against all three experts) was within the range of the manually marked contours among the three readers (approximately 3.8 pixels respectively 18 µm for all experts). The area deviations between the automated and manual segmentation also lie within the range of the area deviations among the 3 clinical experts. Intra reader variability for the experts was between 0.9 and 0.94. We conclude that the automated segmentation approach is able to segment blood vessels with comparable accuracy as expert readers and will provide a useful tool in vessel analysis of whole C-scans, and in particular in multicenter trials.

Interchangeability of macular thickness measurements between different volumetric protocols of Spectralis optical coherence tomography in normal eyes.

BACKGROUNDS: To evaluate in healthy eyes the interchangeability of retinal thickness measurements resulting from different protocols of Spectralis optical coherence tomography (OCT, Heidelberg Engineering, Germany). METHODS: Three different central volumetric protocols were performed in one session by one single operator in a randomly selected eye of 31 healthy adults (range, 19-30 years): (1) area 6 × 6 mm, 25 scan pattern (SP), (2) area 6 × 6 mm, 49 SP, (3) area 6 × 3 mm, 97 SP. Nine ETDRS areas were analyzed, except outer areas for 97 SP. Interclass correlation coefficients (ICC) and limits of agreement (Bland-Altman) were calculated. RESULTS: Mean minimal foveal thickness was 224.0 ± 15.8 µm and central retinal thickness 280.8 ± 16.5 µm. ICC ranged from 0.973 to 0.993. Ninety-five percent limits of agreement between the protocols were <7 µm in all ETDRS areas. The difference between two measurements never exceeded 9 µm. CONCLUSIONS: Spectralis OCT retinal thickness measurements in healthy subjects showed good protocol interchangeability for all tested protocols. Larger differences are to be expected in eyes with macular pathology.