Jens Funk

Reproducibility of Nerve Fiber Layer Thickness Measurements Using 3D Fourier-Domain OCT

PURPOSE Conventional time-domain optical coherence tomography (OCT) has been shown to provide reproducible retinal nerve fiber layer (RNFL) measurements. Recently, high-speed, high-resolution Fourier-domain 3D-OCT has been introduced to improve OCT quality. It can provide 6-mm(2) high-density scans to provide RNFL thickness measurements. The purpose of this study was to test the reproducibility of 3D-OCT RNFL thickness measurements in healthy volunteers. METHODS Thirty-eight eyes were included in the study. High-density 6-mm(2) 3D scans were registered by two independent operators. RNFL thickness was calculated for eight areas corresponding to the ETDRS areas and for two ring areas. The ETDRS grid was centered on the optic disc. Intraclass correlation coefficients (ICC) and coefficients of variation (COV) were calculated. Interobserver reproducibility was visualized by using Bland-Altman analysis. RESULTS Intrasession reproducibility was good with a mean ICC of 0.90. The mean COV for operator 1 and 2 was 4.2% and 4%, respectively (range, 1.9%-6.7%). Highest reproducibility was found for the two ring areas and the superior and inferior quadrants. Mean differences in RNFL thickness measurements for ring 1 and 2 between operator 1 and 2 were 0.9 microm (limits of agreement, -11.4 to +9.6 microm) and 0.1 microm (limits of agreement -4.1 to +3.9 microm), respectively. CONCLUSIONS 3D-OCT RNFL thickness measurements in healthy volunteers showed good intra- and interobserver reproducibility. 3D-OCT provides more RNFL thickness information compared to conventional time-domain OCT measurements and may be useful for the management of glaucoma and other optic neuropathies.

Reproducibility of retinal nerve fiber layer thickness measurements using the eye tracker and the retest function of Spectralis SD-OCT in glaucomatous and healthy control eyes.

PURPOSE To evaluate the impact of Spectralis self-acting eye-tracking (eye tracker) and retest software on the reproducibility of retinal nerve fiber layer (RNFL) thickness measurements in glaucomatous and healthy control eyes by SD-OCT. METHODS RNFL thickness was measured in 56 normal and 47 glaucomatous eyes by one operator within one session with a brief rest between measurements. Three measurements were taken with the eye tracker and the retest function engaged (method A), and three measurements were taken without the eye tracker and without the retest function (method B). Method A and B measurements were taken alternately. RESULTS Reliability, measured by intraclass correlation coefficient (ICC) for absolute agreement and coefficient of variation (COV), was calculated for the global mean RNFL thickness (G), for each sector and for the peripapillary bundle. The ICC (and lower 95% confidence interval [CI]) for the global mean RNFL thickness (G) for method A measurements in both normal and glaucomatous eyes was 0.99 (0.98 CI). In glaucomatous eyes, the COV for method B measurements was between 2.7% and 10.5%, and between 1.3% and 3.5% for method A measurements. CONCLUSIONS The reproducibility of RNFL measurements with Spectralis SD-OCT is excellent in both normal and glaucomatous eyes and can be significantly improved by using the eye tracker and retest software. The gain of reproducibility by using the software is significantly higher in glaucomatous eyes than in normal eyes. These findings suggest that software applications are capable of significantly improving the reproducibility of RNFL thickness measurements.

Repeatability of nerve fiber layer thickness measurements in patients with glaucoma and without glaucoma using spectral-domain and time-domain OCT

BackgroundThe aim of this work is to assess the repeatability of spectral-domain-OCT (SD-OCT) retinal nerve fiber layer thickness (RNFL) thickness measurements in a non-glaucoma group and patients with glaucoma and to compare these results to conventional time-domain-OCT (TD-OCT).MethodsIn a prospective, comparative, observational case-control study, 50 eyes of 25 non-glaucoma and 22 eyes of 11 patients with primary open angle glaucoma (POAG) were included. SD-OCT and TD-OCT circle scans were centered on the optic disc. In each eye, OCT scans were performed three times by two independent observers. RNFL thickness was measured in four quadrants around the optic disc. In addition, the overall mean RNFL thickness was assessed. Intraclass correlation coefficients (ICC) and coefficients of variation (COV) were calculated. Inter-observer and inter-OCT repeatability was visualized by using Bland–Altman analysis.ResultsIntra-observer repeatability for TD- OCT was good with an ICCmean RNFL thickness of 0.939 in non-glaucomas and 0.980 in glaucomatous eyes. For SD-OCT, intra-observer repeatability was higher with an ICC of 0.989 for non-glaucomas and 0.997 for glaucomatous eyes. COVs for TD-OCT ranged from 2.9–7.7% in non-glaucomas and from 6.0–13.3% in glaucoma patients. COVs for SD-OCT ranged from 0.3–1% in non-glaucomas and from 0.9–2.3% in glaucomatous eyes. COVs were influenced by various factors. In the glaucoma group, COVs were significantly higher (p < 0.001) compared to the non-glaucoma group. COVs increased by a mean of 5.1% when TD-OCT was used instead of SD-OCT (p < 0.001).ConclusionsSD-OCT RNFL thickness measurements in healthy volunteers and glaucoma patients showed good intra- and inter-observer repeatability. Especially in glaucomatous eyes, repeatability of SD-OCT was superior to TD-OCT.

Internal reflectivity of filtering blebs versus intraocular pressure in patients with recent trabeculectomy.

PURPOSE The authors conducted a morphology analysis of filtering blebs with anterior segment optical coherence tomography (AS-OCT) in patients shortly after trabeculectomy to find further criteria for success or failure of a filtering bleb. METHODS Thirty-seven patients (43 eyes) who had recently (<2 years) undergone trabeculectomy were measured 1 to 4 times with AS-OCT. In contrast to ultrasound biomicroscopy, AS-OCT eliminates the need for a water bath in contact with the globe. This is of particular value in a study of morphologic parameters that may be altered by contact and in the postoperative period when concerns of infection are paramount. In this study, the internal reflectivity of the fluid-filled cavity of the filtering bleb was compared with the intraocular pressure (IOP). RESULTS Mean age of the patients was 69.5 years (range, 27-84 years). Average preoperative IOP of the 43 eyes was 20.6 mm Hg (range, 10-42 mm Hg), average postoperative IOP at the time of AS-OCT measurement was 10.6 mm Hg (range, 2-40 mm Hg), and mean IOP reduction was 10.0 mm Hg (48.5%). Internal reflectivity of the fluid-filled cavity of the filtering bleb correlated very well to the IOP (R(2) = 0.3762, n = 61, P < 0.0001). CONCLUSIONS AS-OCT is a promising tool with which to analyze the morphology of the filtering bleb after trabeculectomy. A highly significant correlation between the internal reflectivity of the fluid-filled cavity of the filtering bleb and the IOP could be shown that may have future impact in evaluating the postoperative success or failure of filtering blebs.

Repeatability of intraocular pressure measurements with Icare PRO rebound, Tono-Pen AVIA, and Goldmann tonometers in sitting and reclining positions

BackgroundIcare PRO (ICP) is a new Rebound tonometer that is able to measure intraocular pressure (IOP) in both sitting and reclining positions. In this study, the gold standard Goldmann tonometer (GAT) was compared to ICP and Tono-Pen AVIA (TPA). Hypothesis was that repeatability of GAT is superior to ICP and TPA.Methods36 eyes of 36 healthy caucasian individuals, 13 male and 26 females, 17 right and 19 left eyes have been included in this prospective, randomized, cross-sectional study. The study was conducted at a single site (Dept. of Ophthalmology, UniversityHospital Zurich, Switzerland). Primary outcome measures were Intraclass correlation coefficients (ICC) and coefficients of variation (COV) and test-retest repeatability as visualized by Bland-Altman analysis. Secondary outcome measures were IOP in sitting (GAT, ICP and TPA) and in reclining (ICP and TPA) position.ResultsMean IOP measured by GAT was 14.9±3.5 mmHg. Mean IOP measured by ICP was 15.6±3.1 mmHg (with TPA 14.8±2.7 mmHg) in sitting and 16.5±3.5 mmHg (with TPA 17.0±3.0 mmHg) in reclining positions. COVs ranged from 2.9% (GAT) to 6.9% (ICP reclining) and ICCs from 0.819 (ICP reclining) to 0.972 (GAT).ConclusionsRepeatability is good with all three devices. GAT has higher repeatability compared to the two tested hand-held devices with lowest COVs and highest ICCs. IOP was higher in the reclining compared to the sitting position.Trial registrationThe study was registered to the Clinical Trials Register of the US National Institute of Health, NCT01325324.

[Continuous intraocular pressure measurement: First results with a pressure-sensitive contact lens].

BACKGROUND A prototype of a pressure-sensitive contact lens (CL-DCT) based on dynamic contour tonometry (DCT) has been developed for continuous intraocular pressure (IOP) monitoring. The purpose of the present study was to assess the clinical applicability of this CL-DCT. MATERIAL AND METHODS In 24 healthy subjects continuous IOP recording with the CL-DCT for 100 s was accomplished including IOP monitoring during 2 consecutive Valsalva manoeuvres. The measurement procedure was repeated after 5 min on the same eye and compared with the initial measurement. RESULTS Continuous pressure curves were recorded in 20 subjects. The CL-DCT revealed an individual increase in IOP from 0.74 to 8.26 mmHg during the Valsalva manoeuvres. Comparison of the 2 consecutive IOP measurements yielded a mean deviation of +/-0.4 mmHg. CONCLUSIONS CL-DCT allows non-invasive and continuous measurements of IOP. The measured values are comparable to the expected ones. Further studies are necessary to compare the measurement accuracy of CL-DCT with that of slit lamp adapted DCT (SL-DCT).

Evaluation of filtering blebs using the ‘Wuerzburg bleb classification score’ compared to clinical findings

BackgroundTo determine the agreement between intraocular pressure and the ‘Wuerzburg bleb classification score’, as well as between single items of the score and intraocular pressure. Interobserver variability was analyzed.Methods57 post-trabeculectomy eyes were included. Colour photographs were used to score the filtering bleb in accordance to the Wuerzburg bleb classification score by two different examiners. At the same visit, clinical data such as intraocular pressure, best corrected visual acuity, slit lamp biomicroscopy and medical history were obtained by another examiner.ResultsAfter trabeculectomy, 42 out of 57 eyes (73.7%) reached the target pressure (≤21mmHg, and intraocular pressure reduction of at least 20%, without antiglaucoma medication, and without any additional intervention). Fair agreement was found between intraocular pressure and Wuerzburg bleb classification score ≥8 points and ≥7 points (kappa 0.24 and 0.27, respectively). Analyzing the subgroups of the morphological criteria, best agreement was found between occurrence of microcysts and target intraocular pressure (к 0.22 – 0.34).ConclusionsEvaluating filtering blebs after trabeculectomy by using the Wuerzburg bleb classification score is a good technique for predicting intraocular pressure control in eyes attaining a minimum score of seven points. The presence of microcysts on the filtering bleb predicts that the eye is likely to attain target pressure.

Hand‐held dynamic contour tonometry

Purpose:  We present a prototype of the hand‐held dynamic contour tonometer (HH‐DCT) and prospectively compare this HH‐DCT with the well‐established Perkins applanation tonometer (PAT) and the TonoPenXL (TPXL).

Cataract Surgery combined with excimer laser trabeculotomy to lower intraocular pressure: effectiveness dependent on preoperative IOP

BackgroundCataract surgery combined with excimer laser trabeculotomy (phaco-ELT) can reduce intraocular pressure (IOP). The aim of this study was to evaluate the effect of phaco-ELT on IOP in patients as a function of preoperative IOP.MethodsPatients with open-angle glacuoma or ocular hypertension who received phaco-ELT between 01/2008 and 10/2009 were included. Patients were assigned based on preoperative IOP either to the study group (≤21 mmHg) or control group (>21 mmHg) in this IRB-approved, prospective, consecutive case series. Visual Acuity, IOP, and number of anti-glaucoma drugs (AGD) were recorded at baseline and 12 months after phaco-ELT. Any postoperative complications were also recorded.Results64 eyes of 64 patients (76.5 ± 9.4 years) were included. Baseline IOP was 19.8 ± 5.3 mmHg (AGD 2.4 ± 1.1) for all eyes, 16.5 ± 2.9 mmHg (AGD 2.5 ± 1.0) for the study group, and 25.8 ± 2.9 mmHg (AGD 2.2 ± 1.4) for the control group. Across the two groups, IOP was reduced by 4.5 ± 5.9 mmHg (-23.0%, p < 0.001) and AGD by 0.9 ± 1.5 (-38.9%, p < 0.001). For the study group IOP was reduced by 1.9 ± 4.4 mmHg (-11. 5 %, p = 0.012) and AGD by 1.1 ± 1.4 (-42.9%, p < 0.001), and for the control group by 9.5 ± 5.4 mmHg (-36.6%, p < 0.001) and AGD by 0.7 ± 1.6 (-29.5%, p = 0.085). There were no serious postoperative complications such as endophthalmitis, significant hyphema, or a severe fibrinous reaction of the anterior chamber.ConclusionsIOP remained significantly reduced from baseline 12 months after phaco-ELT regardless of preoperative IOP levels, with no major complications. The IOP reduction remained constant over the entire follow-up. Hence, phaco-ELT can be considered in glaucoma and ocular hypertensive patients whenever cataract surgery is performed, in order to further reduce IOP or to reduce the requirement for IOP-reducing medications.

Long-term effect of selective laser trabeculoplasty on intraocular pressure in pseudoexfoliation glaucoma.

BACKGROUND Selective laser trabeculoplasty has been found to be effective as an adjunct to topical medical therapy in glaucoma. This analysis examines the intraocular pressure lowering effect of laser trabeculoplasty in eyes with pseudoexfoliation on maximum medical therapy. MATERIAL AND METHODS A retrospective chart review was undertaken of 457 eyes of which 344 underwent a 360° selective laser trabeculoplasty treatment between 2008 and 2013. 94 of these eyes had pseudoexfoliation. Intraocular pressure values were analysed in 3 monthly intervals up to 60 months after selective laser trabeculoplasty. Exclusion criteria were narrow or closed angles as well as uveitic glaucoma and previous intraocular pressure lowering surgery. RESULTS Patients mean age was 71 years±11.0 SD, 42.7% were male. At time point 12 months after selective laser trabeculoplasty the intraocular pressure lowering effect was significantly greater in eyes with pseudoexfoliation than in eyes without pseudoexfoliation (p=0.01; Mann-Whitney test). Up to 21 months after selective laser trabeculoplasty a significant intraocular pressure reduction of 2.76 mmHg±3.72 SD compared to baseline values could be seen in eyes with pseudoexfoliation (p=0.01; Wilcoxon Test). CONCLUSIONS In this retrospective study a significant greater intraocular pressure lowering effect of selective laser trabeculoplasty could be seen in eyes with pseudoexfoliation compared to eyes without pseudoexfoliation only at time point 12 months after selective laser trabeculoplasty. Analyses revealed no significant intraocular pressure reduction compared to baseline values after 21 months in eyes with pseudoexfoliation and after 30 months in eyes without pseudoexfoliation.