Publications by authors named "Markus Schranz"

11 Publications

  • Page 1 of 1

Identification and quantification of fibrotic areas in the human retina using polarization-sensitive OCT.

Biomed Opt Express 2021 Jul 23;12(7):4380-4400. Epub 2021 Jun 23.

Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria.

Subretinal fibrosis is one of the most prevalent causes of blindness in the elderly population, but a true gold standard to objectively diagnose fibrosis is still lacking. Since fibrotic tissue is birefringent, it can be detected by polarization-sensitive optical coherence tomography (PS-OCT). We present a new algorithm to automatically detect, segment, and quantify fibrotic lesions within 3D data sets recorded by PS-OCT. The algorithm first compensates for the birefringence of anterior ocular tissues and then uses the uniformity of the birefringent optic axis as an indicator to identify fibrotic tissue, which is then segmented and quantified. The algorithm was applied to 3D volumes recorded in 57 eyes of 57 patients with neovascular age-related macular degeneration using a spectral domain PS-OCT system. The results of fibrosis detection were compared to the clinical diagnosis based on color fundus photography (CFP), and the precision of fibrotic area measurement was assessed by three repeated measurements in a sub-set of 15 eyes. The average standard deviation of the fibrotic area obtained in eyes with a lesion area > 0.7 mm was 15%. Fibrosis detection by CFP and PS-OCT agreed in 48 cases, discrepancies were only observed in cases of lesion area < 0.7 mm. These remaining discrepancies are discussed, and a new method to treat ambiguous cases is presented.
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http://dx.doi.org/10.1364/BOE.426650DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8367236PMC
July 2021

Impact of large choroidal vessels on choriocapillaris flow deficit analyses in optical coherence tomography angiography.

PLoS One 2021 3;16(8):e0254955. Epub 2021 Aug 3.

Vienna Clinical Trial Center (VTC), Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.

Purpose: To investigate the impact of large choroidal vessels (LCV) on Choriocapillaris (CC) flow deficit (FD) analyses with swept-source optical coherence tomography angiography (SS-OCTA).

Design: Prospective, cross-sectional study.

Methods: Macular 6x6mm SS-OCTA scans were obtained from intermediate age-related macular degeneration (iAMD) and healthy eyes. Images were captured and processed according to most common standards and analyzed for percentage of flow-deficits (FD%) within four 1x1mm squares at the corners of each image. Choroidal thickness (CT), iris color and refraction error were considered as potential influential factors for LCV visibility. A linear mixed model and logistic regression models were calculated for statistical evaluation.

Results: Sixty-nine iAMD and 49 age-matched healthy eyes were enrolled. LCV were visible in at least one sector in 52% of iAMD and 47% of healthy eyes. Within the iAMD group FD% were significantly lower in areas containing LCV (p = 0.0029). Increasing CT resulted in an odds ratio decrease of LCV (OR: 0.94, p<0.0001). Below a CT value of ≤118μm LCV could be expected with a sensitivity of 86% and a specificity of 85%.

Conclusions: LCV can significantly affect CC FD analyses of SS-OCTA images. Their visibility is negatively associated with CT. The impact of LCV should be taken into account when performing CC FD assessments, especially in patients where reduced CT is to be expected and inclusion of affected areas should be considered carefully.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0254955PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8330935PMC
August 2021

Incidence and surgical care of retinal detachment during the first SARS-CoV-2 lockdown period at a tertiary referral center in Austria.

PLoS One 2021 8;16(3):e0248010. Epub 2021 Mar 8.

Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.

Purpose: To assess the influence of the SARS-CoV-2 lockdown in spring on frequency, severity and quality of care of rhegmatogeneous retinal detachments (RRD) in a tertiary referral center in Vienna, Austria.

Methods: Single center, consecutive case series with historical controls. Patients presenting with primary RRD during the first Austrian SARS-CoV-2 lockdown (March 16th-May 3rd 2020) and a corresponding control group consisting of the same time period of the preceding 3 years.

Results: The mean number of patients with RD in the reference group (RG) was 22 (± 1) and in the lockdown group (LG) 15. Median total delay, defined as onset of symptoms until surgery, in the RG was 5 (lower quartile: 3.0; upper quartile: 8.0) compared to 7 (3.0; 12.0) days in the LG, (p = 0.740). During the lockdown 67% of patients were referred from an external ophthalmologist compared to 52% in the RG, (p = 0.395). 34% of patients in the RG presented with an attached macula compared to 33% in the LG (p = 0.597). PVR was present in 49% of cases in the RG compared to 73% in the LG. Single surgery success (SSS) rates were lower in the LG (73.3%) compared to the RG (85.3%), (p = 0.275).

Conclusion: Patients with RRD during the SARS-CoV-2 lockdown presented and were treated within acceptable time limits, showed the same macula-on ratios but a higher PVR rate and a tendency towards worse SSS rates compared to the time period of the preceding 3 years.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248010PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7939259PMC
March 2021

Three-dimensional composition of the photoreceptor cone layers in healthy eyes using adaptive-optics optical coherence tomography (AO-OCT).

PLoS One 2021 7;16(1):e0245293. Epub 2021 Jan 7.

Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria.

Purpose: To assess the signal composition of cone photoreceptors three-dimensionally in healthy retinas using adaptive optics optical coherence tomography (AO-OCT).

Methods: Study population. Twenty healthy eyes of ten subjects (age 23 to 67). Procedures. After routine ophthalmological assessments, eyes were examined using AO-OCT. Three-dimensional volumes were acquired at 2.5° and 6.5° foveal eccentricity in four main meridians (superior, nasal, inferior, temporal). Cone densities and signal compositions were investigated in four different planes: the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST) and full en-face plane (FEF) combining signals from all mentioned cone layers. Additionally, reliability of a simple semi-automated approach for assessment of cone density was tested. Main outcome measures. Cone density of IS/OS, IS/OS+, COST and FEF. Qualitative depiction and composition of each cone layer. Inter-rater agreement of cone density measurements.

Results: Mean overall cone density at all eccentricities was highest at the FEF plane (21.160/mm2), followed by COST (20.450/mm2), IS/OS+ (19.920/mm2) and IS/OS (19.530/mm2). The different meridians and eccentricities had a significant impact on cone density, with lower eccentricity resulting in higher cone densities (p≤.001), which were highest at the nasal, then temporal, then inferior and then superior meridian. Depiction of the cone mosaic differed between all 4 layers regarding signal size and packing density. Therefore, different cone layers showed evident but not complete signal overlap. Using the semi-automated technique for counting of cone signals achieved high inter-rater reliability (ICC > .99).

Conclusions: In healthy individuals qualitative and quantitative changes in cone signals are found not only in different eccentricities and meridians, but also within different photoreceptor layers. The variation between cone planes has to be considered when assessing the integrity of cone photoreceptors in healthy and diseased eyes using adaptive optics technology.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0245293PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790532PMC
May 2021

Three-dimensional assessment of para- and perifoveal photoreceptor densities and the impact of meridians and age in healthy eyes with adaptive-optics optical coherence tomography (AO-OCT).

Opt Express 2020 Nov;28(24):36723-36739

An adaptive optics optical coherence tomography (AO-OCT) system is used to assess sixty healthy eyes of thirty subjects (age 22 to 75) to evaluate how the outer retinal layers, foveal eccentricity and age effect the mean cone density. The cone mosaics of different retinal planes (the cone inner segment outer segment junction (IS/OS), the cone outer segment combined with the IS/OS (ISOS+), the cone outer segment tips (COST), and the full en-face plane (FEF)) at four main meridians (superior, nasal, inferior, temporal) and para- and perifoveal eccentricities (ecc 2.5° and 6.5°) were analyzed quantitatively. The mean overall cone density was 19,892/mm at ecc 2.5° and 13,323/mm at ecc 6.5°. A significant impact on cone density was found for eccentricity (up to 6,700/mm between ecc 2.5° and 6.5°), meridian (up to 3,700/mm between nasal and superior meridian) and layer (up to 1,400/mm between FEF and IS/OS). Age showed only a weak negative effect. These factors as well as inter-individual variability have to be taken into account when comparing cone density measurements between healthy and pathologically changed eyes, as their combined effect on density can easily exceed several thousand cones per mm even in parafoveal regions.
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http://dx.doi.org/10.1364/OE.409076DOI Listing
November 2020

LONGITUDINAL CHANGES IN QUANTITATIVE AUTOFLUORESCENCE DURING PROGRESSION FROM INTERMEDIATE TO LATE AGE-RELATED MACULAR DEGENERATION.

Retina 2021 Jun;41(6):1236-1241

Department of Ophthalmology and Optometry, Christian Doppler Laboratory for Ophthalmic Image Analysis, Vienna Reading Center, Medical University of Vienna, Vienna, Austria.

Purpose: To prospectively investigate the development of quantitative autofluorescence (qAF) during progression from intermediate to late age-related macular degeneration (AMD).

Methods: Quantitative autofluorescence images from patients with intermediate AMD were acquired every three months with a Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) using a built-in autofluorescence reference. The association between changes in longitudinal qAF and progression toward late AMD was assessed using Cox regression models with time-dependent covariates.

Results: One hundred and twenty-one eyes of 71 patients were included, and 653 qAF images were acquired. Twenty-one eyes of 17 patients converted to late AMD (median follow-up: 21 months; 12 eyes: atrophic AMD; nine eyes: neovascular AMD). The converting patients' mean age was 74.6 ± 4.4 years. Eleven eyes in the converting group (52.4%) were pseudophakic. The presence of an intraocular lens did not affect the qAF regression slopes (P > 0.05). The median change for atrophic AMD was -2.34 qAF units/3 months and 0.78 qAF units/3 months for neovascular AMD. A stronger decline in qAF was significantly associated with an increased risk of developing atrophic AMD (hazard ratio = 1.022, P < 0.001). This association, however, was not present in the group progressing toward neovascular AMD (hazard ratio = 1.001, P = 0.875).

Conclusion: The qAF signal declines with progression to atrophy, contrary to developing neovascularization. Quantitative autofluorescence may allow identification of patients at risk of progressing to late AMD and benefits individualized patient care in intermediate AMD.
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http://dx.doi.org/10.1097/IAE.0000000000002995DOI Listing
June 2021

Profiling neovascular age-related macular degeneration choroidal neovascularization lesion response to anti-vascular endothelial growth factor therapy using SSOCTA.

Acta Ophthalmol 2021 Mar 24;99(2):e240-e246. Epub 2020 Jul 24.

Department of Ophthalmology and Optometry, Vienna Clinical Trial Center (VTC), Medical University of Vienna, Vienna, Austria.

Purpose: To identify the changes in distinct vascular parameters of choroidal neovascularization (CNV) in eyes with treatment-naïve neovascular age-related macular degeneration (nAMD) during the primary response to anti-VEGF therapy using aflibercept.

Methods: Patients were prospectively followed during the first 3 months according to a standardized protocol with mandatory visits at days 7 and 14 after each anti-VEGF treatment up to day 90. Fourteen eyes were seen in addition at days 1 and 3 post-initial injection. Aflibercept was administered at baseline (BL), day 30 and 60. 6 × 6mm SSOCTA (PlexElite, Zeiss) images were acquired. Using the semi-automated AngioTool, CNV area, vessel area, vessel density (VD), the number of junctions, junctions density, total vessel length, average vessel length, total number of endpoints and lacunarity were assessed.

Results: Thirty-two consecutive patients presenting with treatment-naïve, SSOCTA-positive CNV lesions were included. Close follow-up showed a characteristic neovascular response curve with a dynamic decrease in lesion size within days and a reactive increase following 2 weeks after initial treatment. An undulating pattern was seen for all neovascular parameters except for vascular density, with variable statistical significance. Due to a flattening of the therapeutic response as early as after the second treatment, CNV lesion size and most of the related parameters had an increase in activity above baseline values at the end of the loading phase. Lesion size was the leading feature of reactivation by a mean increase of 19.3% after three monthly aflibercept injections. Subgroup analysis based on lesion size revealed a significant correlation between best-corrected visual acuity and quantitative change in lesion size over time, but not baseline size.

Conclusions: Using SSOCTA, a morphologic neovascular response pattern can be identified in anti-VEGF treatment of CNV. A synchronized early decrease and consecutive reactivation in a large spectrum of neovascular biomarkers including size and internal structure are visualized in a qualitative and quantitative manner. SSOCTA analyses allow new insights in CNV morphology changes and therapeutic response.
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http://dx.doi.org/10.1111/aos.14554DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7984400PMC
March 2021

Subretinal Drusenoid Deposits and Photoreceptor Loss Detecting Global and Local Progression of Geographic Atrophy by SD-OCT Imaging.

Invest Ophthalmol Vis Sci 2020 06;61(6):11

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Purpose: To investigate the impact of subretinal drusenoid deposits (SDD) and photoreceptor integrity on global and local geographic atrophy (GA) progression.

Methods: Eighty-three eyes of 49 patients, aged 50 years and older with GA secondary to age-related macular degeneration (AMD), were prospectively included in this study. Participants underwent spectral-domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) imaging at baseline and after 12 months. The junctional zone and presence of SDD were delineated on SD-OCT and FAF images. Linear mixed models were calculated to investigate the association between GA progression and the junctional zone area, baseline GA area, age, global and local presence of SDD and unifocal versus multifocal lesions.

Results: The area of the junctional zone was significantly associated with the progression of GA, both globally and locally (all P < 0.001). SDD were associated with faster growth in the overall model (P = 0.039), as well as in the superior-temporal (P = 0.005) and temporal (P = 0.002) sections. Faster progression was associated with GA baseline area (P < 0.001). No difference was found between unifocal and multifocal lesions (P > 0.05). Age did not have an effect on GA progression (P > 0.05).

Conclusions: Photoreceptor integrity and SDD are useful for predicting global and local growth in GA. Investigation of the junctional zone is merited because this area is destined to become atrophic. Photoreceptor loss visible on SD-OCT might lead to new structural outcome measurements visible before irreversible loss of retinal pigment epithelium occurs.
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http://dx.doi.org/10.1167/iovs.61.6.11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415285PMC
June 2020

Response of Retinal Sensitivity to Intravitreal Anti-angiogenic Bevacizumab and Triamcinolone Acetonide for Patients with Diabetic Macular Edema over One Year.

Curr Eye Res 2020 09 4;45(9):1107-1113. Epub 2020 Feb 4.

Department of Ophthalmology, Medical University of Vienna , Vienna, Austria.

Aim: The aim of this study was to evaluate and compare microperimetry changes in patients with clinically significant diabetic macular edema secondary to diabetes mellitus, following intravitreal injections of bevacizumab or triamcinolone during a follow-up of 1 year after treatment.

Materials And Methods: 30 patients with clinically significant macular edema were randomized into two groups of 15 patients each. One group initially received three intravitreal injections of 2.5 mg bevacizumab at monthly intervals. The other received a single injection of 8 mg of triamcinolone followed by two sham interventions at monthly intervals. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) were measured. Macular function was documented by microperimetry at baseline, 3, 6, 9 months and at the last visit of each patient.

Results: In the bevacizumab group, the mean differential light threshold (±standard deviation) under therapy improved significantly from 8.40 (± 3.8) dB to 12.8 (±4.3) dB at the 12-month follow-up visit (p ≤ .05), whereas in the triamcinolone group it increased from 8.0 (± 2.4) dB at baseline to 9.3 (±3.6) dB at the last visit without reaching statistical significance ( > .05). The mean differential light thresholds between the two groups were not statistically significant at baseline or the last visit ( > .05). In the bevacizumab group, the improvement (slope) in mean differential light threshold was significantly superior to the Triamcinolone group (Estimate = 0.588, p ≤ .05).

Conclusion: Central macular function as measured by microperimetry in patients with acute DME improved in addition to anatomical restoration after intravitreal bevacizumab and triamcinolone injection. In our clinical study, the measures of the variables in patients receiving bevacizumab were superior to those receiving triamcinolone throughout the one-year observation period.
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http://dx.doi.org/10.1080/02713683.2020.1712728DOI Listing
September 2020

Are There Funduscopic and Optical Coherence Tomography Preoperative Characteristics to Predict Surgical Difficulty of Epiretinal Membrane Removal?

Curr Eye Res 2020 08 10;45(8):1012-1016. Epub 2020 Feb 10.

Department of Ophthalmology, Medical University of Vienna , Vienna, Austria.

Purpose: To identify the correlation between preoperative funduscopic and optical coherence tomography characteristics of epiretinal membranes and the difficulty of surgical removal.

Methods: Fifty eyes of 50 patients with an idiopathic epiretinal membrane (ERM) scheduled for pars plana vitrectomy (PPV) and ERM peeling were included. Surgical videos were analyzed and the difficulty of ERM removal (easy or difficult) determined subjectively by an independent surgeon. Furthermore, the peeling time and amount of grasping were measured on the videos to provide an objective factor of surgery difficulty. Preoperative spectral-domain optical coherence tomography (OCT) images and color fundus photos were analyzed to identify predictive factors for membrane removal difficulty.

Results: The subjective surgical difficulty of ERM removal was strongly associated with fibrillary changes between the ERM and retinal nerve fiber layer (RNFL), severe retinal vascular tortuosity and severe glinting fundus reflex. Higher fundus pigmentation was associated with fewer and cystoid spaces with more attempts of grasping ERM. No other preoperative signs were found to be associated with the duration of the peeling time.

Conclusion: The presence of fibrillary changes between the ERM and RNFL, severe retinal vascular tortuosity and severe glinting reflex are preoperative findings that have a strong association with the difficulty in ERM peeling.
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http://dx.doi.org/10.1080/02713683.2020.1712425DOI Listing
August 2020

Comparison of posterior capsule opacification development with 2 single-piece intraocular lens types.

J Cataract Refract Surg 2017 06;43(6):774-780

From the Department of Ophthalmology, Medical University of Vienna, Vienna, Austria. Electronic address:

Purpose: To evaluate the differences in the incidence of posterior capsule opacification (PCO) and visual and optical performance between 2 hydrophobic acrylic single-piece sharp-edged intraocular lenses (IOLs) over 3 years.

Setting: Department of Ophthalmology, Medical University of Vienna, Vienna, Austria.

Design: Prospective randomized case series.

Methods: Patients with bilateral cataract were prospectively randomized to receive an Eyecee One IOL (IOL A) or an Acrysof SN60WF IOL (IOL B) and were followed for 36 months. The corrected distance visual acuity (CDVA) and IOL decentration and tilt were measured. The PCO was quantified by analysis of standardized retroillumination images.

Results: The study comprised 160 eyes of 80 patients. The PCO incidence was low for both IOLs at all follow-up visits. Three years postoperatively, the median objective PCO score was 1.4 (range 0 to 5.6) for IOL A and 1.5 (range 0 to 5.0) for IOL B (P = .67). The neodymium:YAG (Nd:YAG) capsulotomy rate 3 years after surgery was 16.4% and 6.0% (P = .06), respectively. Visual acuity and contrast sensitivity outcomes were also comparable at all follow-up visits.

Conclusions: Both IOLs showed good capsular bag performance and low PCO rates 3 years after surgery. Both IOLs also showed comparable results for visual acuity, contrast sensitivity, decentration and tilt, PCO score, slitlamp examination, and Nd:YAG capsulotomy rates.
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http://dx.doi.org/10.1016/j.jcrs.2017.06.005DOI Listing
June 2017
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