Capillary Refill-The Key to Assessing Dermal Capillary Capacity and Pathology in Optical Coherence Tomography Angiography.

BACKGROUND/OBJECTIVES: Standard optical coherence tomography angiography (OCTA) has been limited to imaging blood vessels actively undergoing perfusion, providing a temporary picture of surface microvasculature. Capillary perfusion in the skin is dynamic and changes in response to the surrounding tissue's respiratory, nutritional, and thermoregulatory needs. Hence, OCTA often represents a given perfusion state without depicting the actual extent of the vascular network. Here we present a method for obtaining a more accurate anatomic representation of the surface capillary network in human skin using OCTA, along with proposing a new parameter, the Relative Capillary Capacity (RCC), a quantifiable proxy for assessing capillary dilation potential and permeability. METHODS: OCTA images were captured at baseline and after compression of the skin. Baseline images display ambient capillary perfusion, while images taken upon capillary refill display the network of existing capillaries at full capacity. An optimization-based automated vessel segmentation method was used to automatically analyze and compare OCTA image sequences obtained from two volunteers. RCC was then compared with visual impressions of capillary viability. RESULTS: Our OCTA imaging sequence provides a method for mapping cutaneous capillary networks independent of ambient perfusion. Differences between baseline and refill images clearly demonstrate the shortcomings of standard OCTA imaging and produce the RCC biometric as a quantifiable proxy for assessing capillary dilation potential and permeability. CONCLUSION: Future dermatological OCTA diagnostic studies should implement the Capillary Refill Methods over standard imaging techniques and further explore the relevance of RCC to differential diagnosis and dermatopathology. Lasers Surg. Med. © The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.

Selective retina therapy for acute central serous chorioretinopathy.

AIMS: To evaluate selective retina therapy (SRT) as a treatment of acute central serous chorioretinopathy. METHODS: 30 eyes of 30 patients with central serous chorioretinopathy of at least a 3 months' duration were recruited. 14 eyes were randomised to an SRT group (Q-switched neodymium-doped yttrium lithium fluoride (Nd:YLF) laser, wavelength 527 nm, t=1.7 µs, energy 100-370 µJ, spot diameter 200 µm, pulse repetition rate 100 Hz,) and 16 eyes to a control group. After 3 months of follow-up, patients in the control group with persistence of subretinal fluid (SRF) were allocated to a cross-over group, treated with SRT and followed up for further 3 months. The main outcome measures were change of best-corrected Early Treatment Diabetic Retinopathy Study visual acuity (BCVA) and SRF. RESULTS: At 3 months of follow-up, the mean (SD) improvement of BCVA was significantly greater after SRT than in the control group: 12.7 (7.2) versus 6.3 (8.9) letters (p=0.04). SRF had decreased significantly more after SRT as compared with that the control group: 203 (136) µm versus 41 (150) µm (p=0.005). In eight eyes allocated to the cross-over group, the mean BCVA had increased during 3 months of follow up before SRT by 1.4 (5.2) letters and continued to increase during 3 months following SRT by 7.4 (6.3) letters, while SRF increased by 39.5 (160.2) µm before SRT and decreased by 151.5 (204.9) µm after SRT. In six of the eight eyes, SRF had completely resolved 3 months after SRT. CONCLUSIONS: SRT appears to expedite functional recovery and the re-absorption of SRF as compared with that in untreated controls. A larger prospective, randomised phase 3 confirmative patient study is warranted. TRIAL REGISTRATION NUMBER: NCT00987077.

Slit-lamp-adapted fourier-domain OCT for anterior and posterior segments: preliminary results and comparison to time-domain OCT.

PURPOSE: To evaluate the diagnostic potential of a slit-lamp (SL)-adapted Fourier-domain (= spectral radar, SR) optical coherence tomography (OCT)-SL-SR-OCT-instrument as an in vivo imaging device for use in examinations of the anterior and posterior segments. MATERIALS AND METHODS: In a pilot study, 88 eyes from 70 healthy volunteers and patients were examined using a prototype Fourier-domain SL-SR-OCT system. Results were compared to those from the following commercially available systems: the 1310-nm SL-OCT (Heidelberg Engineering, Heidelberg, Germany) for anterior segment and the Stratus OCT (Zeiss Meditec, Jena, Germany) for posterior segment imaging. Our SL-SR-OCT provides 1025 axial scans, 5000 Hz line-scan frequency, scan length of up to 8 mm, axial depth in air of 3.5 mm, and resolution of 9 mum. For posterior visualization, a hand-held 78-diopter ophthalmoscopic lens was used. RESULTS: Our SL-SR-OCT system allowed simultaneous scanning with direct biomicroscopic and SL imaging of anterior and posterior segment structures. Anatomical structures and pathological changes were displayed with high resolution and excellent contrast. Measurements of corneal and retinal thickness were possible. In comparison to images obtained by the SL-OCT, our SL-SR-OCT boasted a higher resolution, thus providing more clinically relevant details of the corneal epithelium, internal structure of filtering blebs, etc. Complete imaging of the chamber angle was limited, however, due to the backscattering properties of the sclera at 830 nm. For posterior segment imaging, excellent delineation of the macula and optic nerve head details, with a distinct portrayal of macular pathology and retinal edema, was possible with SL-SR-OCT. CONCLUSION: SL-SR-OCT enables detailed imaging of physiological and pathological anterior and posterior segment structures. As a multi-purpose device, it offers a wide spectrum of applications, with high-quality OCT-imaging, in a comfortable setting without the need to move the patient.

[Optical coherence tomography: from retina imaging to intraoperative use - a review]. / Ubersicht der apparativen Entwicklungen in der optischen Kohärenztomografie: von der Darstellung der Retina zur Unterstützung therapeutischer Eingriffe.

BACKGROUND: Optical coherence tomography (OCT) is new diagnostic procedure that has rapidly evolved in the last years. The recently developed spectral domain OCT allows one to increase the imaging speed by a hundred times compared to the first generation time domain OCT and enables three-dimensional imaging as well as real-time imaging of fast moving structures. Volumetric imaging improves the quantitative measurement of morphology and the evaluation of temporal changes. In addition, an exact correlation with images acquired with other imaging modalities is possible. Real-time imaging enables also the use of OCT during examinations with the slit-lamp and during ophthalmological surgery. METHODS: A spectral domain OCT was adapted to a slit lamp. 70 patients (91 eyes) were examined at the anterior or posterior segment of the eye. Images of healthy structures and different pathologies were compared to OCT images obtained with Stratus 3, Spectralis, and the SL-OCT. To demonstrate the feasibility of OCT during surgery, spectral domain OCT devices working with 20,000 and 210,000 A scans per second were coupled by specially developed optics to the camera port of a surgical microscope. The device was tested with phantoms and enucleated pig eyes. RESULTS AND CONCLUSIONS: A 5 kHz spectral domain OCT can image the retina during slit lamp-based indirect ophthalmoscopy with a quality similar to that of the Stratus 3. In addition, relevant structures of the anterior segment were imaged. Here, compared to commercially available devices, the imaged field was smaller and the angle of the anterior chamber was not directly visible due to the 830 nm wavelength, which had to be used for retinal imaging. Through the surgical microscope, a volumetric imaging of epithelium, Bowman's, Descemet's membranes, limbus, iris, lens, conjunctiva and sclera was demonstrated with several tens of centimetre working distance. Instruments and incisions in the cornea were visualised with 20 microm precision. Real-time imaging and visualisation of volumetric OCT data were also demonstrated. In principle, all technical problems of an intraoperative use of OCT have been solved and a clinical trial will start in the near future. OCT has the potential to improve the precision of surgical interventions and may even enable new interventions.

[Basic principles and clinical application of retinal laser therapy]. / Grundlagen und klinische Anwendung der Lasertherapie an der Netzhaut.

The scientific background of laser photocoagulation of the ocular fundus was studied extensively by several investigators in the 1970 s and 1980 s. The basic principles were successfully resolved during that time and clinical consequences for proper application of the laser photocoagulation for various diseases were deduced. The present paper gives an overview about the physical basics of laser-tissue interactions during and after retinal laser treatment and the particular laser strategies in the treatment of different retinal diseases. Thus, it addresses the issue of the impact on tissue of laser parameters as wavelength, spot size, pulse duration and laser power. Additionally, the different biological tissue reactions after laser treatment are presented, such as, e. g., for retinopexia or macular treatments as well as for diabetic retinopathies. Specific laser strategies such as the selective laser treatment of the RPE (SRT) or the transpupillary thermotherapy (TTT) are presented and discussed.

Numerical modelling of conductive and convective heat transfers in retinal laser applications.

The control of the temperature increase is an important issue in retinal laser treatments. Within the fundus of the eye heat, generated by absorption of light, is transmitted by diffusion in the retinal pigment epithelium and in the choroid and lost by convection due to the choroidal blood flow. The temperature can be spatially and temporally determined by solving the heat equation. In a former analytical model this was achieved by assuming uniform convection for the whole fundus of the eye. A numerical method avoiding this unrealistic assumption by considering convective heat transfer only in the choroid is used here to solve the heat equation. Numerical results are compared with experimental results obtained by using a novel method of noninvasive optoacoustic retinal temperature measurements in rabbits. Assuming global convection the perfusion coefficient was evaluated to 0.07 s(-1), whereas a value of 0.32 s(-1)--much closer to values found in the literature (between 0.28 and 0.30 s(-1))--was obtained when choroidal convection was assumed, showing the advantage of the numerical method. The modelling of retinal laser treatment is thus improved and could be considered in the future to optimize treatments by calculating retinal temperature increases under various tissues and laser properties.

[Selective retina therapy: methods, technique, and online dosimetry]. / Selektive Retinatherapie: Methodik, Technik und Online-Dosimetrie.

Selective retina therapy (SRT) is currently under evaluation, as a new and very subtle laser method, for the treatment of retinal disorders associated with a degradation of the retinal pigmentary epithelium (RPE). SRT makes it possible to selectively effect the RPE, sparing the adjacent neural retina with the photoreceptors and also the choroid below the RPE. In the best case, the therapy leads to regeneration of the RPE and a long-term metabolic increase at the chorio-retinal junction. In contrast to conventional laser photocoagulation, which is associated with complete thermal necrosis of and around the treated site, absolutely no scotoma occurs in SRT. This paper reviews the methods and mechanisms behind the selective effects of the RPE. In vitro and preclinical results are used to describe the bandwidth of selective effects with respect to different irradiation settings. An optoacoustic technique is introduced to visualize effects that cannot be seen by ophthalmoscopy and to facilitate dosimetry control without recourse to angiography completes the report.

[Selective retina therapy in central serous chorioretinopathy with detachment of the pigmentary epithelium]. / Selektive Retina-Therapie bei Retinopathia centralis serosa mit Pigmentepithelabhebung.

BACKGROUND: Selective Retina Therapy (SRT) is a new and innovative laser treatment modality that selectively treats the retinal pigmentary epithelium while sparing the photoreceptors. This therapeutic concept appears to be particularly suitable for treating patients with acute or chronic central serous chorioretinopathy (CSC). We present preliminary results obtained in five patients who had CSC associated with pigmentary epithelium detachment (PED) and serous subretinal fluid (SRF) and who were treated with SRT. METHODS: This case series was made up of five male patients (mean age 47 years) with chronic CSC and SRF resulting from PED. Examinations performed before and at 1 month and 3 months after the treatment were: BCVA, FLA, OCT (Zeiss OCT III). For SRT, confluent treatment of the PED (area of leakage) was carried out using a pulsed frequency-doubled, Q-switched Nd-YLF prototype laser (lambda=527 nm, t= 1.7 s, 100 Hz, energy = 150-250 J). RESULTS: Best corrected visual acuity at baseline was 0.53, while after 4 weeks it was 0.56 and after 12 weeks, 0.5. At baseline leakage was seen at the PED on fluorescein angiography in all patients. After 4 weeks leakage activity was no longer noted on angiography in 4 of 5 patients. OCT at baseline showed SRF at the edge of the PED in all patients, but in 4 of the 5 patients this was no longer detectable after 4 weeks. CONCLUSION: SRT is a safe and effective treatment for patients with CSC in which PED has caused SRF. Not a single case of rip syndrome was observed in this study, even though the PED was treated confluently. Since SRT spares the photoreceptors it is particularly suitable for the treatment of CSC, especially when the origin of leakage is located close to the fovea. The results indicate that SRT leads to reconstruction of the outer blood-retina barrier.

[Selective retina therapy in patients with diabetic maculopathy]. / Selektive Retina-Therapie bei Patienten mit diabetischer Makulopathie.

Selective Retina Therapy (SRT) is a new laser treatment that selectively targets the retinal pigmen epithelium (RPE). In this study, we treated 39 patients presenting with nonischemic, focal and focal-diffuse diabetic maculopathy with SRT. In the main. the results indicate that SRT had stabilizing effects on visual acuity, angiographic leakage, lipid exudation, and foveal retinal thickness. SRT is safe and is especially useful for treating pathologies that are located close to the fovea, which cannot be treated with conventional argon laser photocoagulation.

Selective retina therapy in patients with central serous chorioretinopathy.

BACKGROUND: Central serous chorioretinopathy (CSC) is a disease with a localized breakdown of the outer blood-retinal barrier located within the retinal pigment epithelium (RPE) causing subretinal fluid accumulation. Selective retina therapy (SRT) is a new, minimally invasive laser technology that has been designed to selectively target the RPE. SRT spares retinal tissue. METHODS: Twenty-seven eyes of 27 patients with active CSC were treated with SRT using a pulsed double-Q-switched Nd-YLF prototype laser (lambda=527 nm, t=1.7 micros). At baseline, best-corrected visual acuity was determined and fluorescein angiography and optical coherence tomography were performed. The patients were followed for up to 3 months. RESULTS: After 4 weeks 85.2% of patients showed complete resolution of subretinal fluid and in 96.3% there was no leakage visible on fluorescein angiography. After 3 months 100% of patients demonstrated no subretinal fluid and 100% of patients had no leakage activity on fluorescein angiography. Visual acuity, 20/40 at baseline, improved to 20/28 after 4 weeks and to 20/20 after 3 months. CONCLUSION: SRT is a safe and effective treatment for active CSC. Especially if the RPE leak is located close to the fovea, SRT is the favoured therapeutic option. We recommend earlier treatment of patients with acute CSC in order to prevent development of chronic changes due to CSC with irreversible anatomical and functional damage. SRT might be considered as a first-line treatment for active CSC.

Comparison of reduced and standard light application in photodynamic therapy of the eye in two rabbit models.

BACKGROUND: Current PDT treatment for age-related macular degeneration uses a standard radiant exposure of 50 J/cm(2) at an irradiance of 600 mW/cm(2). However; there is a general problem with the unusually high irradiance; in fact, the rate of photochemical production of singlet oxygen may be limited by insufficiently oxygenized neovascular tissue. It was the aim of this study to evaluate the efficacy of verteporfin (Visudyne) photoactivation to induce thrombosis of choriocapillaries and in experimentally induced corneal neovascularizations in rabbits by varying irradiance and retinal radiant exposure. MATERIALS AND METHODS: The light-dose threshold to induce micro-thrombosis in the choriocapillaries (seven eyes) and in corneal neovascularizations (eight eyes) of Chinchilla-Bastard rabbits using different retinal irradiances (100 and 600 mW/cm(2)) at different radiant exposures (20, 10, 5, 2.5, 1.25, 0.62, and 0.3 J/cm(2)) was evaluated. Induction of neovascularizations was performed 7 days prior to PDT treatment using intracorneal silk sutures. A dose of 2 mg/kg verteporfin was intravenously infused 10 min before standard PDT. The criterion for vascular thrombosis was vessel closure as determined by fluorescein angiography 1 h and 1 day post exposure. RESULTS: Experiments on the choroid revealed vessel closure 1 h after irradiation at ED(50) = 10.8 J/cm(2) (both 600 and 100 mW/cm(2)) and after 24 h at ED(50) = 2.4 J/cm(2) (600 mW/cm(2)) versus 1.8 J/cm(2) (100 mW/cm(2)). Vessel closure was enhanced at irradiation with 100 mW/cm(2). Regarding corneal neovascularizations, vessel thrombosis was observable by dark appearance of irradiated clotted neovascular tissue and angiographically by a lack of leakage at ED(50) thresholds of 0.62 J/cm(2) (1 h) and 0.41 J/cm(2) (1 day) for 100 mW/cm(2) and of 0.99 J/cm(2) (1 h), and 0.67 J/cm(2) (1 day) for 600 mW/cm(2). Thus in both experiments thresholds for vessel closure were reduced by a factor of 1.5 for the lower intensity. Histology revealed more selective vessel occlusion without RPE and photoreceptor damage for 100 mW/cm(2) rather than 600 mW/cm(2) intensity at threshold irradiation. CONCLUSION: Low-intensity PDT with verteporfin for neovascular tissue seems to be more effective than regular high-intensity PDT. Future preclinical trials should address the issue of proper dosimetry for effective PDT in age-related macular degeneration.

Selective retina therapy (SRT): a review on methods, techniques, preclinical and first clinical results.

Selective retina therapy (SRT) is a new laser procedure for retinal diseases that are thought to be associated with a degradation of the retinal pigment epithelium (RPE). The aim of the irradiation is to selectively damage the RPE without affecting the neural retina, the photoreceptors and the choroid. Goal of the treatment is to stimulate RPE cell migration and proliferation into the irradiated areas in order to improve the metabolism at the diseased retinal sites. In a pilot study more than 150 patients with soft drusen, retinopathia centralis serosa (RCS) and macular edema were treated. The first 3-center international trial targets diabetic macular edema and branch vein occlusion. In this review, selective RPE effects are motivated and two modalities to achieve selective RPE effects will be introduced: a pulsed and a continuous wave scanning mode. The mechanism behind selective RPE-effects will be discussed reviewing in vitro results and temperature calculations. So far clinical SRT is performed by applying trains of 30 laser pulses from a Nd:YLF-Laser (527 nm, 1.7 micros, 100 Hz) to the diseased fundus areas. In the range of 450-800 mJ/cm(2) per pulse, RPE-defects in patients were proved angiographically by fluorescein or ICG-leakage. The selectivity with respect to surrounding highly sensitive tissue and the safety range of the treatment will be reviewed. With the laser parameters used neither bleeding nor scotoma, proved by microperimetry, were observed thus demonstrating no adverse effects to the choroid and the photoreceptors, respectively. During and after irradiation, it shows that the irradiated locations are ophthalmoscopically invisible, since the effects are very limited and confined to the RPE, thus a dosimetry control is demanded. We report on a non-invasive opto-acoustic on-line technique to monitor successful RPE-irradiation and compare the data to those achieved with standard angiography one-hour post treatment.

Topographic angiography and optical coherence tomography: a correlation of imaging characteristics.

PURPOSE: Topographic angiography (TAG) using confocal scanning laser angiography and optical coherence tomography (OCT) are new imaging modalities that have been introduced during recent years. OCT and TAG imaging were compared to specify the characteristics of each imaging modality. METHODS: TAG using fluorescein angiography (FA) provides a three-dimensional profile of the vascular structures based on the analysis of a set of 32 confocal images over a depth of 4 mm. OCT provides cross-sectional images of the neurosensory retina and the retinal pigment epithelium-choriocapillary complex (RPE-CC). The authors compared and evaluated both modalities in 10 patients with predominantly classic choroidal neovascularization (CNV), 10 patients with serous pigment epithelial detachment (PED), and 10 patients with geographic RPE atrophy, all secondary to age-related macular degeneration (ARMD). RESULTS: In patients with classic CNV, TAG detected neovascular structures and delineated their configuration. In PEDs pooling of extravascular fluid is demonstrated, and in geographic RPE atrophy TAG showed reduced choroidal perfusion. Classic CNV was demonstrated by OCT as a hyperreflective band at the level of the RPE-CC, and PED showed a dome-shaped RPE detachment. In geographic RPE atrophy, OCT imaged loss of the RPE band and had an increased depth resolution. CONCLUSIONS: TAG and OCT are useful imaging modalities in the evaluation of ARMD cases. TAG visualizes the vascular configuration and dynamic perfusion and leakage changes. OCT is able to document intra-, subretinal, and sub-RPE fluid accumulation secondary to CNV. Both modalities may provide further valuable insight into ARMD pathogenesis, enhance diagnostic quality, and improve the assessment of therapeutic effects.

[Three-dimensional imaging of photodynamic effects and spontaneous course in choroidal neovascularization]. / Dreidimensionale Darstellung photodynamischer Effekte und des Spontanverlaufs bei chorioidalen Neovaskularisationen.

PURPOSE: Photodynamic therapy (PDT) induces occlusive and regenerative effects in choroidal neovascularization (CNV) and physiological choroid. The process of vascular alteration is documented quantitatively and qualitatively by three-dimensional angiography. METHOD: In a prospective, randomized trial 30 patients with subfoveal CNV due to age-related macular degeneration (AMD) were treated with PDT or placebo. Fluorescence series with 32 tomographic images over a 4-mm depth were analyzed topographically and reproduced in a three-dimensional display. RESULTS: At initial presentation CNV lesions were documented as a well-defined prominence in all patients. In the verteporfin group CNV height continuously decreased with each interval. In the placebo group CNV slightly increased in height during the first 6 months and remained stable at about 90% of the initial prominence at long-term follow-up. After 12 months 44% of the patients in the verteporfin group developed an additional choroidal defect. CONCLUSION: Three-dimensional angiography offers a reliable documentation of CNV progression and regression during PDT. A decrease in CNV size is associated with an increase in choroidal perfusion defects.

[Retinal photoablation with the Erbium:YAG laser. Initial experimental results for traction-free removal of tissue]. / Retinale Photoablation mit dem Erbium:YAG-Laser. Erste experimentelle Ergebnisse zur traktionsfreien Gewebeabtragung.

BACKGROUND: To investigate the potential of an Er:YAG laser for precise and traction-free removal of retinal layers in vitro. MATERIAL AND METHODS: Retinal ablation in porcine retinal explants was performed using a free running Er:YAG laser focused either into a low-OH quartz fiber or a sapphire fiber. The explants were treated under air or perfluorodecaline (PFD). The ablation depth was evaluated by optical coherence tomography (OCT) and histology sections. RESULTS: A radiant exposure of 5.0 J/cm(2) under air and PFD resulted in complete transsection of the neurosensory retina. Between 3.5 and 2.0 J/cm(2) the ablation depth and the defect patterns varied markedly and adjacent thermal zones areas were seen. Below 2.0 J/cm(2) no defects could be created in air, whereas under PFD the ablation extended into the ganglion cell layer. Ablations using a sapphire fiber and 2.0 J/cm(2) showed a significantly higher reproducibility of ablation depth, and homogeneous defect patterns limited to the nerve fiber layer could be produced without thermal damage. CONCLUSIONS: The Er:YAG laser system with a low-OH quartz fiber allowed ablation of inner retinal layers in vitro, but revealed a variable ablation depth and low reproducibility.However, a sapphire fiber showed markedly improved results. Therefore its use during vitreoretinal surgery seems possible not only as a cutting device but also as a tool for the ablation of fine retinal structures.

[Fundus autofluorescence after selective RPE laser treatment]. / Fundus-Autofluoreszenz nach selektiver RPE-Laserbehandlung.

BACKGROUND: The selective RPE laser treatment is a new technique which selectively damages the RPE and avoids adverse effects to the neural retina. A problem is the ophthalmoscopically non-visibility of the laser lesions. The aim of the study was to investigate whether fundus autofluorescence (AF), which is derived from the lipofuscin contained by the RPE cells, is changed due to the RPE damage, and thus may be used for non-invasive treatment control. METHODS: A total of 26 patients with macular diseases, i.e. diabetic maculopathy (DMP), soft drusen maculopathy (AMD) and central serous retinopathy (CSR), were treated with repetitive short laser pulses (800 ns) from a green Nd:YAG laser (parameters: 532 nm, 100 and 50 pulses at 500 and 125 Hz, retinal spot diameter 200 micrometer, pulse energies 70-175 microJ). AF was excited by 488 nm and detected by a barrier filter at 500 nm (HRA, Heidelberg engineering). Patients were examined by ophthalmoscopy, fluorescein angiography and autofluorescence measurements at various times after treatment (i.e. 1 h, 1 and 6 weeks, 3, 6 and 12 months). RESULTS: None of the laser lesions was ophthalmoscopically visible during treatment although fluorescein angiography showed leakage of the irradiated areas. Identification of the lesions was possible by AF imaging showing an intensity decay in the irradiated area in 22 out of 26 patients, predominantly in patients with CSR and AMD. Lesions could be identified as hypoautofluorescent spots 1 h after treatment. During follow-up the laser spots became hyperautofluorescent. In patients with DMP some AF images were less helpful due to diffuse edema and larger retinal thickness. CONCLUSION: Imaging of non-visible selective RPE laser effects can be achieved by AF measurements predominantly in patients without retinal edema. Thus AF may replace invasive fluorescein angiography in many cases to verify therapeutic laser success.

Autofluorescence imaging after selective RPE laser treatment in macular diseases and clinical outcome: a pilot study.

AIM: Selective retinal pigment epithelium (RPE) laser treatment is a new technique which selectively damages the RPE while sparing the neural retina. One difficulty is the inability to visualise the laser lesions. The aim of the study was to investigate whether fundus autofluorescence (AF) is changed because of the RPE damage, and thus might be used for treatment control. Additionally, the clinical course of patients with various macular diseases was evaluated. METHODS: 26 patients with macular diseases (diabetic maculopathy (DMP), soft drusen maculopathy (AMD), and central serous retinopathy (CSR)) were treated and followed up for at least 6 months. Treatment was performed with a train of repetitive short laser pulses (800 ns) of a frequency doubled Nd:YAG laser (parameters: 532 nm, 50 and 500 pulses at 100 and 500 Hz, retinal spot diameter 200 micro m, pulse energies 75-175 micro J). AF was excited by 488 nm and detected by a barrier filter at 500 nm (HRA, Heidelberg Engineering, Germany). Patients were examined by ophthalmoscopy, fluorescein angiography, and autofluorescence measurements at various times after treatment (10 minutes, 1 hour, 1 and 6 weeks, 3, 6, and 12 months). RESULTS: Fluorescein angiography showed leakage from the irradiated areas for about 1 week after treatment. None of the laser lesions was ophthalmoscopically visible during treatment. Identification of the lesions was possible by AF imaging showing an intensity decay in the irradiated area in 22 out of 26 patients, predominantly in patients with CSR and AMD. Lesions could be identified 10 minutes after treatment as hypoautofluorescent spots, which were more pronounced 1 hour later. During follow up the laser spots became hyperautofluorescent. In patients with DMP some AF images were less helpful because of diffuse oedema and larger retinal thickness. In these cases ICG angiography was able to confirm therapeutic success very well. Most of the patients have had benefit from the treatment, with best results obtained for CSR patients. CONCLUSION: Imaging of non-visible selective RPE laser effects can be achieved by AF measurements predominantly in patients without retinal oedema. Therefore, AF may replace invasive fluorescein angiography in many cases to verify therapeutic laser success. Selective laser treatment has the potential to improve the prognosis of macular diseases without the risk of laser scotomas.

Three-dimensional topographic angiography in chorioretinal vascular disease.

PURPOSE: To evaluate a new angiographic technique that offers three-dimensional imaging of chorioretinal vascular diseases. METHODS: Fluorescein (FA) and indocyanine green angiography (ICGA) were performed using a confocal scanning laser ophthalmoscope. Tomographic series with 32 images per set were taken over a depth of 4 mm at an image frequency of 20 Hz. An axial analysis was performed for each x/y position to determine the fluorescence distribution along the z-axis. The location of the onset of fluorescence at a defined threshold intensity was identified and a depth profile was generated. The overall results of fluorescence topography were displayed in a gray scale-coded image and three-dimensional relief. RESULTS: Topographic angiography delineated the choriocapillary surface covering the posterior pole with exposed larger retinal vessels. Superficial masking of fluorescence by hemorrhage or absorbing fluid did not preclude detection of underlying diseases. Choroidal neovascularization (CNV) appeared as a vascular formation with distinct configuration and prominence. Chorioretinal infiltrates exhibited perfusion defects with dye pooling. Retinal pigment epithelium detachments (PEDs) demonstrated dynamic filling mechanisms. Intraretinal extravasation in retinal vascular disease was detected within a well-demarcated area with prominent retinal thickening. CONCLUSIONS: Confocal topographic angiography allows high-resolution three-dimensional imaging of chorioretinal vascular and exudative diseases. Structural vascular changes (e.g., proliferation) are detected in respect to location and size. Dynamic processes (e.g., perfusion defects, extravasation, and barrier dysfunction) are clearly identified and may be quantified. Topographic angiography is a promising technique in the diagnosis, therapeutic evaluation, and pathophysiological evaluation of macular disease.

[Examination of the cornea using optical coherence tomography]. / Untersuchungen der Hornhaut mittels optischer Kohärenztomographie.

INTRODUCTION: This study evaluated the clinical use of optical coherence tomography (OCT) for two-dimensional representation of the cornea. PATIENTS AND METHODS: Noncontact slitlamp-adapted OCT was used in selected cases to evaluate pathologically altered corneas and to measure the central corneal thickness and curvature. RESULTS: OCT provided correlation between differences in reflection and morphological changes. Scar tissue resulted in hyper-reflective light scattering, whereas cystic lesions were hyporeflective. Precise biomorphometry also allowed representation of intrastromal and retrocorneal changes. Central corneal thickness measured by OCT yielded reproducible values and corneal curvature could be calculated from the optical signals of the corneal surface. CONCLUSIONS: OCT provides high-resolution representation of the cornea and exact evaluation of its morphology, thickness, and curvature. Due to the noncontact, simple, and rapid examination using the slitlamp the corneal OCT method is a promising additional diagnostic modality.