Biomechanical in vitro evaluation of the kangaroo spine in comparison with human spinal data.

On the basis of the kangaroo's pseudo-biped locomotion and its upright position, it could be assumed that the kangaroo might be an interesting model for spine research and that it may serve as a reasonable surrogate model for biomechanical in vitro tests. The purpose of this in vitro study was to provide biomechanical properties of the kangaroo spine and compare them with human spinal data from the literature. In addition, references to already published kangaroo anatomical spinal parameters will be discussed. Thirteen kangaroo spines from C4 to S4 were sectioned into single-motion segments. The specimens were tested by a spine tester under pure moments. The range of motion and neutral zone of each segment were determined in flexion and extension, right and left lateral bending and left and right axial rotation. Overall, we found greater flexibility in the kangaroo spine compared to the human spine. Similarities were only found in the cervical, lower thoracic and lumbar spinal regions. The range of motion of the kangaroo and human spines displayed comparable trends in the cervical (C4-C7), lower thoracic and lumbar regions independent of the motion plane. In the upper and middle thoracic regions, the flexibility of the kangaroo spine was considerably larger. These results suggested that the kangaroo specimens could be considered to be a surrogate, but only in particular cases, for biomechanical in vitro tests.

Morphometry of the kangaroo spine and its comparison with human spinal data.

The upright posture of the kangaroo suggests that the spine of the kangaroo could be a possible substitute model for biomechanical studies of the human spine. A prerequisite for this should be the agreement of anatomy in humans and kangaroos. The purpose of this study was to investigate the anatomical parameters of the kangaroo spine from C4 to S4 and compare them with existing anatomical data of the human spine. Eight complete spines of the red giant kangaroo were obtained and 21 anatomical parameters were measured from the vertebral bodies, spinal canal, endplate, pedicles, intervertebral discs, transverse, and spinous processes. Most similarities between kangaroo and human spines were found for the vertebral bodies in the cervical and the lumbar spine. The largest differences were evident for the spinous processes. Although both species are somehow upright, these differences may be explained by the way how they move. Jumping probably requires more muscle strength than walking on two legs.

Photodynamic therapy with double duration for circumscribed choroidal haemangioma: functional and anatomical results based on initial parameters.

IMPORTANCE: Pre-treatment symptoms longer than 12 months and foveal cystoid changes are indicators for poor anatomical and functional outcome after photodynamic therapy (PDT). BACKGROUND: To evaluate the prognostic factors on the effectiveness of PDT with double duration for treatment of exudative circumscribed choroidal haemangioma. DESIGN: Retrospective study. PARTICIPANTS: Twenty-seven patients with symptomatic exudative circumscribed choroidal haemangioma treated with PDT. METHODS: Clinical charts of patients with exudative circumscribed choroidal haemangioma treated with PDT were analysed with regard to visual acuity, duration of symptoms, subfoveal fluid, foveal cystoid changes and foveal thickness in optical coherence tomography. MAIN OUTCOME MEASURES: Change of best-corrected visual acuity, sub- and intrafoveal fluid and foveal thickness measured with optical coherence tomography from baseline to last follow-up. RESULTS: Mean visual acuity improved by 0.05 from 0.42 logMAR (standard deviation [SD] 0.34) to 0.37 logMAR (SD 0.47). In 70% of the patients, PDT stopped exudation and revealed a dry fovea. The recurrence or persistence of sub- or intrafoveal fluid was significantly associated with pre-therapeutic symptoms existing for more than 12 months (P = 0.046). Mean foveal thickness in optical coherence tomography decreased from 324 µm (SD 223 µm) to 209 µm (SD 109 µm). CONCLUSIONS AND RELEVANCE: PDT proved to be a safe and effective treatment procedure for exudative circumscribed choroidal haemangioma in our series, with few side effects. We observed a more successful treatment with regard to anatomical and functional results in cases with pre-existing symptoms less than 12 months and in cases without pre-therapeutic foveal cystoid changes.

Desynchronization of Cartesian k-space sampling and periodic motion for improved retrospectively self-gated 3D lung MRI using quasi-random numbers.

PURPOSE: To demonstrate that desynchronization between Cartesian k-space sampling and periodic motion in free-breathing lung MRI improves the robustness and efficiency of retrospective respiratory self-gating. METHODS: Desynchronization was accomplished by reordering the phase (ky ) and partition (kz ) encoding of a three-dimensional FLASH sequence according to two-dimensional, quasi-random (QR) numbers. For retrospective respiratory self-gating, the k-space center signal (DC signal) was acquired separately after each encoded k-space line. QR sampling results in a uniform distribution of k-space lines after gating. Missing lines resulting from the gating process were reconstructed using iterative GRAPPA. Volunteer measurements were performed to compare quasi-random with conventional sampling. Patient measurements were performed to demonstrate the feasibility of QR sampling in a clinical setting. RESULTS: The uniformly sampled k-space after retrospective gating allows for a more stable iterative GRAPPA reconstruction and improved ghost artifact reduction compared with conventional sampling. It is shown that this stability can either be used to reduce the total scan time or to reconstruct artifact-free data sets in different respiratory phases, both resulting in an improved efficiency of retrospective respiratory self-gating. CONCLUSION: QR sampling leads to desynchronization between repeated data acquisition and periodic respiratory motion. This results in an improved motion artifact reduction in shorter scan time. Magn Reson Med 77:787-793, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Free breathing 1H MRI of the human lung with an improved radial turbo spin-echo.

OBJECTIVE: To optimize a radial turbo spin-echo sequence for motion-robust morphological lung magnetic resonance imaging (MRI) in free respiration. MATERIALS AND METHODS: A versatile multi-shot radial turbo spin-echo (rTSE) sequence is presented, using a modified golden ratio-based reordering designed to prevent coherent streaking due to data inconsistencies from physiological motion and the decaying signal. The point spread function for a moving object was simulated using a model for joint respiratory and cardiac motion with a concomitant T2 signal decay and with rTSE acquisition using four different reordering techniques. The reordering strategies were compared in vivo using healthy volunteers and the sequence was tested for feasibility in two patients with lung cancer and pneumonia. RESULTS: Simulations and in vivo measurements showed very weak artifacts, aside from motion blur, using the proposed reordering. Due to the opportunity for longer scan times in free respiration, a high signal-to-noise ratio (SNR) was achieved, facilitating identification of the disease as compared to standard half-Fourier-acquisition single-shot turbo spin-echo (HASTE) scans. Additionally, post-processing allowed modifying the T2 contrast retrospectively, further improving the diagnostic fidelity. CONCLUSION: The proposed radial TSE sequence allowed for high-resolution imaging with limited obscuring artifacts. The radial k-space traversal allowed for versatile post-processing that may help to improve the diagnosis of subtle diseases.

Reducing contrast contamination in radial turbo-spin-echo acquisitions by combining a narrow-band KWIC filter with parallel imaging.

PURPOSE: Cartesian turbo spin-echo (TSE) and radial TSE images are usually reconstructed by assembling data containing different contrast information into a single k-space. This approach results in mixed contrast contributions in the images, which may reduce their diagnostic value. The goal of this work is to improve the image contrast from radial TSE acquisitions by reducing the contribution of signals with undesired contrast information. METHODS: Radial TSE acquisitions allow the reconstruction of multiple images with different T2 contrasts using the k-space weighted image contrast (KWIC) filter. In this work, the image contrast is improved by reducing the band-width of the KWIC filter. Data for the reconstruction of a single image are selected from within a small temporal range around the desired echo time. The resulting dataset is undersampled and, therefore, an iterative parallel imaging algorithm is applied to remove aliasing artifacts. RESULTS: Radial TSE images of the human brain reconstructed with the proposed method show an improved contrast when compared with Cartesian TSE images or radial TSE images with conventional KWIC reconstructions. CONCLUSION: The proposed method provides multi-contrast images from radial TSE data with contrasts similar to multi spin-echo images. Contaminations from unwanted contrast weightings are strongly reduced.

DC-gated high resolution three-dimensional lung imaging during free-breathing.

PURPOSE: To use the acquisition of the k-space center signal (DC signal) implemented into a Cartesian three-dimensional (3D) FLASH sequence for retrospective respiratory self-gating and, thus, for the examination of the whole human lung in high spatial resolution during free breathing. MATERIALS AND METHODS: Volunteer as well as patient measurements were performed under free breathing conditions. The DC signal is acquired after the actual image data acquisition within each excitation of a 3D FLASH sequence. The DC signal is then used to track respiratory motion for retrospective respiratory gating. RESULTS: It is shown that the acquisition of the DC signal after the imaging module can be used in a 3D FLASH sequence to extract respiratory motion information for retrospective respiratory self-gating and allows for shorter echo times (TE) and therefore increased lung parenchyma SNR. CONCLUSION: The acquisition of the DC signal after image signal acquisition allows successful retrospective gating, enabling the reconstruction of high resolution images of the whole human lung under free breathing conditions.

Immunoglobulin G Concentrations in Alpaca Colostrum during the First Four Days after Parturition.

Colostrum provides the newborn with nutrients and immunoglobulins. Immunoglobulins and their intestinal transfer play a major role in the immune system of neonates since they are born agammaglobulinemic. In this study immunoglobulin G (IgG) content was determined in alpaca colostrum and the correlations of the IgG concentration by fat, protein, lactose and minerals were calculated. Colostrum samples were collected daily from 20 multiparous alpaca mares during the first four days after parturition. The IgG concentrations were determined by radial immunodiffusion using a Camelid IgG Test Kit. The IgG concentration decreased significantly from 26,319 mg/dL on day 1 to 3848.8 mg/dL on day 4. There were significant correlations between IgG concentration and the other components of the colostrum. While the correlations between IgG and fat (r = -0.69, p ≤ 0.001) and lactose (r = -0.64, p ≤ 0.001) were negative, the correlations with protein (r = 0.91, p ≤ 0.001), magnesium (r = 0.86, p ≤ 0.001) and cobalt (r = 0.87, p ≤ 0.001) were strongly positive. Due to the strong association, the colostrum protein concentration could be used for a brief estimation of the IgG content.

Full macular translocation (FMT) versus photodynamic therapy (PDT) with verteporfin in the treatment of neovascular age-related macular degeneration: 2-year results of a prospective, controlled, randomised pilot trial (FMT-PDT).

BACKGROUND: To report the outcome of best-corrected visual acuity (BCVA), near visual acuity (NVA), contrast sensitivity (CS) and vision-related quality of life (VRQOL) in patients 2 years after undergoing photodynamic therapy (PDT) or full macular translocation (FMT) for the treatment of neovascular age-related macular degeneration (AMD). METHODS: Fifty patients with predominantly classic subfoveal choroidal neovascularisation (CNV) secondary to AMD were randomized to PDT or FMT. BCVA was determined according a standardized protocol with ETDRS charts. NVA were calculated after testing with SNAB (Swiss National Association of and for the Blind) visual acuity cards. CS was measured with Pelli-Robson charts. The 39-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25 plus supplement) was performed. Primary end points were the changes of BCVA, NVA, CS and VRQOL at 24-month examination. RESULTS: A stabilisation of BCVA (+0.3 letters) was found in the FMT group, whereas a decrease of more than 12 letters (-12.6 letters) was found in the PDT group (p = 0.052). Mean NVA improved by 7.0 letters in the FMT group and was superior to the PDT group (-9.6 letters, p = 0.036), while mean CS showed a time-dependent decrease in both treatment groups (FMT: -3.3 letters, PDT: -3.8 letters, p = 0.726). Considering the results of the VRQOL scores, the improvement of the subscales scores for general vision (p = 0.015), mental health (p = 0.028) and near activity (p = 0.020) were significantly higher in the FMT group. CONCLUSIONS: FMT can stabilise BCVA and improve NVA over a period of 2 years in patients with subfoveal classic CNV secondary to neovascular AMD, whereas a decrease of BCVA and NVA was found in the PDT group. CS did not differ between FMT and PDT. A significant increase of VRQOL scores was only found in the FMT group and not in the PDT group. FMT seems to be a therapeutic approach that can increase visual function resulting in an improvement of patient's VRQOL, but exhibits a higher number of severe complications compared to PDT.

Increasing robustness of radial GRASE acquisition for SAR-reduced brain imaging.

PURPOSE: To improve a radial multi-slice 2D gradient- and spin-echo (GRASE) sequence and provide an appropriate image reconstruction technique for SAR-reduced high-resolution neuroimaging. METHODS: Additional readout gradients per radio-frequency (RF) refocusing allow for a reduced number of RF pulses. In this way, a specific absorption rate (SAR) reduction is achieved and the application at high-field systems becomes more feasible. A phase insensitive image reconstruction is proposed to reduce signal dropout artifacts originating from opposite readout polarities. In addition, the image reconstruction allows for the calculation of images with varying contrast from one measurement. RESULTS: Results obtained at 3T and 7T demonstrate a SAR-reduction of at least 66% for a single-slice experiment with radial GRASE. The reduced SAR is used for an increased spatial coverage without increasing the measurement time. Experiments at 3T and 7T showed that the visual image quality is comparable to standard TSE and GRASE sequences with the same measurement parameters. Using higher EPI factors and the presented image reconstruction, artifact-free images with a significant SAR-reduction can be achieved. CONCLUSION: Radial GRASE enables SAR-reduced acquisitions of high-resolution brain images with different contrasts from one measurement and is a promising sequence for high-field neuroimaging.

Epiretinal deposit of triamcinolone acetonide at the posterior pole after intravitreal injection.

The authors investigated possible toxic side effects of epiretinal triamcinolone acetonide deposits at the posterior pole after an intravitreal injection in both a vitrectomized and a non-vitrectomized eye. The vitrectomized eye developed massive epiretinal triamcinolone acetonide deposits at the posterior pole that were less pronounced in the non-vitrectomized eye. After resolution of the deposits, no morphologic signs of retinal toxicity were apparent. Mild scattered visual field defects did not correlate with the localization of the triamcinolone acetonide deposits. However, because recent in vitro studies indicate potential cytotoxicity, patients should be instructed to keep their heads in an upright position after intravitreal triamcinolone acetonide injection to avoid deposits at the posterior pole.

Early electroretinographic features of streptozotocin-induced diabetic retinopathy.

BACKGROUND: This study set out to document the early electrophysiological and immunohistochemical changes that occur in the retina of experimentally induced diabetic rats. METHODS: Diabetes was induced in rats by intraperitoneal injection of 60 mg/kg of streptozotocin (STZ). Electroretinogram readings were taken monthly under either short-duration or long-duration stimuli for up to 3 months after STZ. Oscillatory potentials (OP) and the amplitudes and implicit times of a- and b-waves were analysed, and b-wave amplitudes were analysed using a Naka-Rushton fit. Scotopic a-waves were analysed with photoreceptor models, and Rmp3 (the maximum a-wave amplitude) and S (sensitivity) were calculated. Three months after STZ injection, immunohistochemistry for glial fibrillary acidic protein was performed on the retinas of the STZ-treated rats and age-matched controls. RESULTS: The implicit OP times were significantly longer in the diabetic rats as compared with the controls, and this difference was noted as early as 1 month following STZ treatment. Other electrophysiological parameters, such as OP amplitudes, a- and b-wave amplitude as well as the implicit times, did not differ from controls at this stage. The sacrificed STZ-treated rats also demonstrated marked enhancement of glial fibrillary acidic protein immunoreactivity, suggesting that at least in experimentally induced diabetic retinopathy there is increased Müller cell reactivity. CONCLUSION: The results of this study indicated that functional alterations in the retina develop rapidly after the onset of diabetes. Analysis of each electroretinogram component may be useful in further investigating the development mechanisms of diabetic retinopathy.

Consequences of verteporfin photodynamic therapy on choroidal neovascular membranes.

OBJECTIVE: To examine the impact of photodynamic therapy (PDT) on angiogenesis in human choroidal neovascular membranes with respect to vascular endothelial growth factor (VEGF) expression, proliferation, and vascularization. METHODS: Retrospective review of an interventional case series of 50 patients (50 eyes) who underwent removal of choroidal neovascular membranes. Choroidal neovascularization was secondary to age-related macular degeneration. Twenty patients were treated with PDT 3 to 655 days before surgery. Choroidal neovascular membranes were stained for CD34, CD105, Ki-67, cytokeratin 18, and VEGF. Thirty choroidal neovascular membranes secondary to age-related macular degeneration without previous treatment were used as controls. RESULTS: Specimens without pretreatment disclosed varying degrees of vascularization, proliferative activity, and VEGF expression by different cells. Specimens treated with PDT 3 days earlier showed mostly occluded vessels, damaged endothelial cells, and low proliferative activity. In contrast, specimens excised at later time points after PDT were highly vascularized and proliferating. This chronology was associated with an impressive VEGF immunoreactivity unique to retinal pigment epithelial cells shortly after PDT that also shifted to other cells at later time points. CONCLUSIONS: Photodynamic therapy induces selective vascular damage in choroidal neovascular membranes. The effectiveness and selectivity of this treatment, however, seem to be jeopardized by a rebound effect initiated by enhanced VEGF expression in retinal pigment epithelial cells.

Human Vision-Motivated Algorithm Allows Consistent Retinal Vessel Classification Based on Local Color Contrast for Advancing General Diagnostic Exams.

PURPOSE: Abnormalities of blood vessel anatomy, morphology, and ratio can serve as important diagnostic markers for retinal diseases such as AMD or diabetic retinopathy. Large cohort studies demand automated and quantitative image analysis of vascular abnormalities. Therefore, we developed an analytical software tool to enable automated standardized classification of blood vessels supporting clinical reading. METHODS: A dataset of 61 images was collected from a total of 33 women and 8 men with a median age of 38 years. The pupils were not dilated, and images were taken after dark adaption. In contrast to current methods in which classification is based on vessel profile intensity averages, and similar to human vision, local color contrast was chosen as a discriminator to allow artery vein discrimination and arterial-venous ratio (AVR) calculation without vessel tracking. RESULTS: With 83% ± 1 standard error of the mean for our dataset, we achieved best classification for weighted lightness information from a combination of the red, green, and blue channels. Tested on an independent dataset, our method reached 89% correct classification, which, when benchmarked against conventional ophthalmologic classification, shows significantly improved classification scores. CONCLUSIONS: Our study demonstrates that vessel classification based on local color contrast can cope with inter- or intraimage lightness variability and allows consistent AVR calculation. We offer an open-source implementation of this method upon request, which can be integrated into existing tool sets and applied to general diagnostic exams.

Chorioretinal neovascularization after radial optic neurotomy for central retinal vein occlusion.

Radial optic neurotomy was recently introduced for the treatment of central retinal vein occlusion. Two patients developed chorioretinal neovascularization through the radial cut of the optic disc after pars plana vitrectomy, radial optic neurotomy, and endophotocoagulation. Patients undergoing radial optic neurotomy should be closely observed to minimize the risk of this complication.

Daily honey consumption does not change CYP3A activity in humans.

Several studies investigating the interaction of honey and drug-metabolizing enzymes showed controversial results, with some suggesting that honey induces CYP3A-mediated metabolism in mammals and humans. This clinical trial was conducted to determine the effect of repeated honey administration on human CYP3A enzyme activity using midazolam as a marker substance. In a randomized, single-blind, parallel-group study, 20 healthy volunteers were randomly assigned to receive either honey (2 × 20 g/d) or artificial honey (2 × 20 g/d) over a period of 10 days. To determine intestinal and hepatic CYP3A activity, oral (4 mg) and intravenous (2 mg) midazolam was administered in a semi-simultaneous way before honey administration, after the last honey administration, and 1 and 6 days thereafter. At baseline after oral midazolam, the partial metabolic clearance was similar in both groups (honey: 917.8 ± 234.6 mL/min vs artificial honey: 973.5 ± 373.8 mL/min). Ten days of honey administration did not change partial metabolic clearance (honey: 1016 ± 268 mL/min vs artificial honey: 1043 ± 450 mL/min), which was also true 1 and 6 days later. Neither honey nor artificial honey in amounts usually consumed affected the intestinal and hepatic CYP3A activity in healthy volunteers.

Assessment of the posterior segment of the cat eye by optical coherence tomography (OCT).

OBJECTIVES: To assess the feasibility of optical coherence tomography (OCT) for examining the cat ocular fundus, to provide normative data on retinal thickness in different fundus regions, and to demonstrate selected surgically induced vitreoretinal pathologies in the cat. ANIMAL STUDIED: Forty-five eyes of 28 healthy domestic cats and two eyes of domestic cats that had undergone subretinal implantation surgery for a visual prosthesis were examined. PROCEDURES: An optical coherence tomograph (Zeiss-Humphrey) was used to examine the anesthetized animals. At least five vertical and five horizontal scans in regular distribution were recorded for each cat including (1) the peripapillary region, (2) the area centralis, and (3) the peripheral retina. Thickness was measured manually at five locations in each scan. Retinal thickness was compared in the three above-mentioned fundus regions, between eyes and between vertical and horizontal scans. OCT was additionally performed in animals with retinal detachment and a subretinal visual prosthesis. RESULTS: OCT measurements required only minimal adjustments of human settings and yielded high quality images. In comparison to humans intraretinal layers were more difficult to differentiate. Retinal thickness was highest in the peripapillary region (245 +/- 21 microm), followed by the peripheral retina (204 +/- 11 microm) and the area centralis (182 +/- 11 microm; all P < 0.0001). There was no statistically significant difference between right and left eye or between vertical and horizontal scans. OCT demonstrated retinal detachment, an iatrogenic break and a subretinal prosthetic device in high detail. CONCLUSIONS: Retinal thickness was measurable with high precision; values compare well to older histologic studies. OCT bears significant advantages over histology in enabling one to repeat measurements in living animals and thus allowing longitudinal studies. Various vitreoretinal pathologies common in feline eyes are detectable and quantifiable by OCT.

Compound subretinal prostheses with extra-ocular parts designed for human trials: successful long-term implantation in pigs.

BACKGROUND: Subretinal implants aim to replace photoreceptor function in patients suffering from degenerative retinal disease like retinitis pigmentosa by topically applying electrical stimuli in the subretinal space. This study-as a last step before upcoming human trials-explored a newly developed surgical technique for permanent implantation of complex subretinal implants with extra-ocular parts. METHODS: The implant consisted of a microphoto-diode array (MPDA) with 1550 electrodes and a 4x4 array of gold electrodes for direct electrical stimulation; both were mounted onto a polyimide foil for transscleral placement into the subretinal space. The foil carried connection lanes to a silicone cable that was implanted under the skin and led to a stimulator box in the animal's neck. Surgery was performed in 11 domestic pigs. Improved vitreo-retinal surgical technique consisted of a 180 degrees peripheral retinotomy and use of diathermy to penetrate the choroid in order to avoid choroidal haemorrhage. Subretinal forceps were used to place the implant safely onto the retinal pigment epithelium before the retina was flattened, peripheral laser photocoagulation was applied and the eye was filled with silicon oil. The implant was stabilized by a scleral fixation patch, use of a metal clamp with bone screws on the animal's skull and a tissue ring under the animal's skin in the neck. Behaviour was observed in the freely moving animals after direct subretinal electrical stimulation and funduscopy, optical coherence tomography, fluorescein angiography and histology were performed. RESULTS: All implants were successfully placed subretinally. In three animals a proliferative vitreo-retinopathy was observed after approximately 2 weeks. Otherwise, funduscopy and OCT demonstrated complete retinal attachment and FA showed no retinal vascular abnormalities over and around the implant. The animals showed clear behavioural reactions to electrical stimulation over the whole examination period. Histological examination failed to show any voltage-induced alteration in the cellular architecture of the retina overlying the stimulation electrodes. CONCLUSIONS: This study demonstrates the feasibility of a new surgical procedure for highly safe and controlled implantation of complex subretinal devices with extra-ocular parts. The new implant design proved to be safely implantable in free-moving pigs for an observation period of 4 weeks.

Photodynamic therapy with verteporfin for choroidal neovascularization associated with angioid streaks.

BACKGROUND: Choroidal neovascularizations (CNV) is the major cause of significant visual loss in patients with angioid streaks. We evaluated the functional and morphological outcome of Verteporfin photodynamic therapy (PDT) in the treatment of these patients. METHODS: This was a retrospective study in two tertiary referral centres over a 3-year period. Examinations included visual acuity assessment with ETDRS charts, binocular fundoscopy and fluorescein angiography. PDT was performed with standard parameters; earlier retreatments were feasible in active CNV. RESULTS: Fifteen eyes from 12 patients (9 male, 3 female) with a follow-up of 12-50 months (mean 26.1, median 19 months) were included. Five lesions were extra-or juxtafoveal and ten were subfoveal. Baseline visual acuity was between 20/63 and 20/16 (mean 20/32, median 20/32). Eyes were treated with two to eight treatments of PDT (mean 4.2, median 4). Treatment intervals were between 5.6 and 72 weeks (mean 12.1, median 9.2 weeks). At the 1-year follow-up, visual acuity was below 20/200 in 27% (4/15), 20/200 or better in 73% (11/15) and 20/63 or better in 47% (7/15) with an improvement of >3 lines in 13% (2/15), no change in 27% (4/15) and a decrease of >3 lines in 60% (9/15). At the final follow-up examination, all lesions were located subfoveally. Visual acuity was below 20/200 in 47% (7/15), 20/200 or better in 53% (8/15) and 20/63 or better in 13% (2/15) with a change in visual acuity between +2 and -18 lines (mean -9 lines, median -8 lines). No change was noted in 7% (1/15) and a decrease of >3 lines in 93% (14/15) of eyes. The maximum measured greatest linear dimension of the lesion during the follow-up varied between 2400 microm and 6200 microm (mean 3680 microm, median 3600 microm) with an increase in the lesion size compared with baseline values between +/-0 microm and +3700 microm (mean+1420 microm, median+1500 microm). CONCLUSION: PDT for CNV associated with angioid streaks seemed to slow down but not prevent the progression of the disease and associated visual loss. Further modifications of the treatments parameters or a combination with other therapeutical options seem warranted for a more effective treatment of these lesions.

In vivo assessment of subretinally implanted microphotodiode arrays in cats by optical coherence tomography and fluorescein angiography.

BACKGROUND: Following multiple promising investigations into restoration of vision in degenerative retinal disease by implantation of a sub- or epiretinal prosthesis, the step to clinical use in humans is impending. In this study we intended to establish optical coherence tomography (OCT) and fluorescein angiography (FA) first in research animals for noninvasive assessment of the condition of the posterior pole of eyes after intraocular implant surgery. METHODS: Three adult cats that had undergone subretinal implant surgery were evaluated by OCT and FA between 1 and 470 days postoperatively. Eight adult cats served as control. In addition histology was performed. RESULTS: In all three cats OCT demonstrated stable positioning of the implants in the subretinal space during the complete examination period. Transient retinal edema was found in the early postoperative period but decreased during follow-up. The retina over the implants was well attached at all times in cats 1 and 2; however, in cat 3 localized retinal detachment was demonstrated. FA showed intact retinal vasculature over the subretinal implant in high detail without interference from choroidal background fluorescence. CONCLUSIONS: OCT and FA have been fruitfully applied to cats to assess the morphological and circulatory conditions of the neuroretina and of its interface with the subretinal implant. The techniques may therefore provide a tool for objective, noninvasive in vivo evaluation of eyes that have undergone subretinal implant surgery, both in research animals and in humans.