Michael Stur

Compact, low-cost Ti:Al2O3 laser for in vivo ultrahigh-resolution optical coherence tomography

A compact, low-cost, prismless Ti:Al2O3 laser with 176-nm bandwidth (FWHM) and 20-mW output power was developed. Ultrahigh-resolution ophthalmic optical coherence tomography (OCT) ex vivo imaging in an animal model with approximately 1.2-microm axial resolution and in vivo imaging in patients with macular pathologies with approximately 3-microm axial resolution were demonstrated. Owing to the pump laser, this light source significantly reduces the cost of broadband OCT systems. Furthermore, the source has great potential for clinical application of spectroscopic and ultrahigh-resolution OCT because of its small footprint (500 mm x 180 mm including the pump laser), user friendliness, stability, and reproducibility.

Choroidal blood flow and progression of age-related macular degeneration in the fellow eye in patients with unilateral choroidal neovascularization.

PURPOSE Cardiovascular risk factors such as smoking, hypertension, and atherosclerosis seem to play an important role in the development of choroidal neovascularization (CNV). Recent studies have also provided evidence suggesting that choroidal and retinal blood flow is decreased in patients with AMD. On the basis of these results, the hypothesis for this study was that lower choroidal blood flow is associated with an increased risk of CNV in patients with AMD. METHODS Forty-one patients with unilateral choroidal neovascular AMD were included in this observational longitudinal study. The fellow eyes of the patients served as study eyes. Subfoveal choroidal blood flow (FLOW) and fundus pulsation amplitude (FPA) were assessed with laser Doppler flowmetry and laser interferometry, respectively. A multivariate COX-regression model was used to test the hypothesis that low choroidal perfusion parameters are associated with the development of CNV. RESULTS Of the 37 patients that were followed up until the end of the study, 17 developed CNV and 20 did not. The univariate COX-regression analysis shows that lower FLOW, systolic blood pressure, intraocular pressure, and FPA are risk factors for development of CNV. Moreover, the more advanced the AMD in the study eye, the higher the risk for CNV to develop in the fellow eye. Multivariate COX regression analysis indicated that only FLOW (P = 0.0071), FPA (P = 0.0068), and staging (P = 0.031) had statistically significant influences on the progression to CNV. CONCLUSIONS The present study indicates that lower choroidal perfusion is a risk factor for the development of CNV in the fellow eye of patients with unilateral CNV.

Ultrahigh resolution optical coherence tomography of macular holes.

Purpose: To evaluate ultrahigh resolution optical coherence tomography (UHR OCT) for visualization of intraretinal layers, especially the photoreceptor inner segment and outer segment layers, in eyes with macular holes and after surgical intervention. Methods: An UHR OCT system based on a titanium:sapphire laser was used, enabling in vivo cross-sectional retinal imaging with 3-&mgr;m axial resolution. Typical, representative tomograms of 5 of 48 eyes from 36 patients demonstrated the potential of UHR OCT to detect morphologic changes in different stages of full-thickness macular holes and changes induced by surgical intervention. Results: UHR OCT could detect subtle intraretinal changes in macular hole formation. Unprecedented visualization of photoreceptor impairment was achieved that appeared to be more extensive than the hole itself. Postoperatively, clinically closed holes showed restoration of the photoreceptor inner and outer segment layers of various extents, with residual disease in some eyes. Conclusion: In macular holes, UHR OCT allows for detection of even small morphologic changes of the retinal layers, especially the photoreceptor inner and outer segment layers. Therefore, it also represents a superior method to monitor the effect of surgical interventions. Preoperative photoreceptor impairment and the degree of postoperative restoration could possibly be associated with visual function. Hence, UHR OCT could lead to better understanding of macular hole pathogenesis and to more accurate disease prognosis.

Ocular photodynamic therapy--standard applications and new indications (part 1). Review of the literature and personal experience.

Ocular photodynamic therapy (PDT) was introduced as a novel treatment for neovascular forms of age-related macular degeneration and choroidal neovascularization (CNV) secondary to pathologic myopia in the mid/end 1990s. The current treatment recommendations are based on the results of two large, prospective, multicenter, randomized clinical trials (Treatment of Age-Related Macular Degeneration with Photodynamic Therapy and Verteporfin in Photodynamic Therapy Studies) and thousands of patients have been treated worldwide over the last years. Meanwhile, PDT has been performed in several other ocular pathologies with some remarkable results, however, with most reports being case reports and small case series without statistical significance. These extended applications include CNV secondary to choroiditis and retinochoroiditis, angioid streaks, central serous chorioretinopathy, retinal angiomatous proliferation, parafoveal telangiectasia or CNV associated with macular dystrophy and idiopathic CNV, as well as diseases without CNV, such as choroidal hemangioma, retinal hamartoma, choroidal melanoma, chronic central serous chorioretinopathy, angiomatous lesions secondary to systemic diseases, rubeosis iridis or neovascular glaucoma. To date, with the introduction of anti-VEGF therapy, the role of PDT will certainly change. However, it is reasonable to believe that it will maintain an important role in combination therapy due to its unique properties of selective vascular targeting. Therefore, it is essential for the ophthalmologist to be familiar with the extended applications and their modifications of treatment parameters. This review will summarize the standard and experimental applications of PDT based on our own results and the literature.

Ocular Photodynamic Therapy – Standard Applications and New Indications (Part 2)

Photodynamic therapy (PDT) has become a well-established treatment for vascular forms of age-related macular degeneration (AMD). The implementation of evidence-based medicine principles into the treatment regimen of AMD seems to be immensly important, since AMD continues to be the most frequent cause of blindness among patients older than 65 years in industrialized countries. Numerous randomized prospective studies demonstrated high levels of evidence for the efficacy of various treatment approaches such as laser photocoagulation, PDT, subretinal surgery or novel anti-angiogenic drugs [Arch Ophthalmol 2006;124:597–599]. The high evidence shown by these studies supported the rationale to use PDT also in additional, less frequent, vasoproliferative diseases. Although these ‘case series’ and ‘individual case control studies’ have a low level of evidence, they give us important information for treatment decisions in these rare conditions. The goal of this survey is to review the current literature regarding PDT in vasoproliferative and exudative ocular diseases outside AMD. Many studies modified the treatment parameters of PDT to address the specific pathology of the underlying disease. Table 1 summarizes the diseases and treatment parameters that are described in this part 2, the entire table of this review is included in part 1 (www.karger.com/doi/10.1159/ 000101922).

Influence of viscoelastic substances used in cataract surgery on corneal metabolism and endothelial morphology: Comparison of Healon and Viscoat

Purpose: To evaluate the influence of cohesive and dispersive ophthalmic viscosurgical devices (OVDs) on endothelial morphology and corneal metabolism during cataract surgery. Setting: Department of Ophthalmology, University of Vienna Medical School, Vienna, Austria. Methods: In this prospective randomized blind study, 50 eyes of 43 patients were randomized into 2 groups before surgery. Phacoemulsification with implantation of a posterior chamber intraocular lens was performed in all patients. In half the patients, sodium hyaluronate 1% (Healon®) was used as the OVD and in the other half, sodium hyaluronate 3%‐chondroitin sulfate 4% (Viscoat®). Corneal metabolism was evaluated by fluorophotometric measurement of corneal autofluorescence. The corneal fluorescence values were corrected for interference by fluorescence of the ocular lens. Specular microscopy (Noncon Robo SP800, Canon) was used to evaluate the endothelial cell density, coefficient of variation, and percentage of hexagonal cells. Examinations were performed preoperatively and 3 days, 1 and 4 weeks, and 3 months postoperatively. Results: There were no significant changes between preoperative and postoperative endothelial cell density measurements in either group (P = .1717). The percentage of hexagonal cells was similar (P = .3489); however, there was a slightly increasing tendency toward polymorphism in both groups. Corneal autofluorescence decreased 3 days after surgery, increased after 1 week, and decreased again subsequently in both groups. There was no significant difference in the influence on corneal metabolism between the 2 OVDs (P = .9899). Conclusions: There was no significant difference between Healon and Viscoat. Thus, this study did not confirm an advantage of either for endothelial protection of healthy corneas.

Intravitreal injection of tissue plasminogen activator and gas in subretinal hemorrhage caused by age-related macular degeneration.

Purpose: To assess the efficacy and safety of intravitreal injection of recombinant tissue plasminogen activator and sulfur hexaflucride gas for displacement of subretinal hemorrhages in patients with age‐related macular degeneration. Methods: The authors injected 25 μg of recombinant tissue plasminogen activator and 0.5 mL sulfur hexafluoride gas intravitreally in 11 patients with subretinal hemorrhages of less than 3 weeks duration. Anatomic and functional results were evaluated. Results: Displacement of subretinal blood was successful within the first week after surgery in 10 of 11 patients. This was accompanied by visual improvement in eight patients. After 1 year, visual acuity was better than before surgery in five patients. Diagnosis of a choroidal neovascularization by fluorescein angiography was possible in all patients, and was treated with laser photocoagulation in five. The authors observed no adverse effects of treatment. Conclusion: Recombinant tissue plasminogen activator and gas effectively displace subretinal blood in patients with age‐related macular degeneration. Randomized studies are necessary to prove the benefit of this simple and safe method in patients with subretinal hemorrhage due to age‐related macular degeneration.

Primary silicone oil tamponade without retinopexy in highly myopic eyes with central macular hole detachments.

Background: In highly myopic macular hole central retinal detachments, the ideal treatment is still under discussion. In our study, we analyzed anatomic and functional outcomes for eyes undergoing vitrectomy with primary silicone oil filling without central photocoagulation, using the oil as inductor and scaffold for glial closure of the causative macular hole. Methods: Eleven patients with central macular hole detachments and myopia ranging from −10.0 to −23.0 diopters underwent vitrectomy and primary silicone oil filling without laser photocoagulation of the central retina. After at least 3 months (mean ± SD, 5.2 ± 2.0 months), the oil was removed from all eyes. Results: In all eyes, the retina was attached by the first postoperative day and remained attached after silicone oil removal until the end of the follow-up period. No severe intra- or postoperative complications were noted. Visual acuity increased in 7 (63.6%) of 11 eyes, remained unchanged in 3 (27.3%) of 11, and deteriorated in 1 (9.1%) of 11. Conclusion: Vitrectomy plus primary silicone oil tamponade without endophotocoagulation is an effective method to treat central macular hole detachments in highly myopic eyes.

Photodynamic therapy and vitelliform lesions.

Purpose: To investigate the effect of photodynamic therapy (PDT) with verteporfin on patients with vitelliform lesions caused by cuticular drusen or adult-onset foveomacular vitelliform dystrophy (AOFVD). Design: Observational case series. Patients and Methods: Eight eyes of seven patients from two centers were examined prospectively. Each patient received PDT with verteporfin applied to the vitelliform lesions. Results: Photodynamic therapy did not significantly affect the median visual acuity outcome (20/50 before PDT and 20/66 after PDT) in all seven treated patients. Of note, however, were four eyes of four patients who experienced a severe decrease in visual acuity after PDT with verteporfin. The temporary relationship of the vision loss to the treatment suggests that this may represent an adverse effect from therapy. The fluorescein angiographic appearance was virtually unchanged in all treated patients, whereas indocyanine green angiography showed typical PDT-associated reduction of choroidal perfusion in the treatment area. Conclusion: Photodynamic therapy does not have a positive influence on the visual outcome in patients with vitelliform lesions and may have a negative impact on vision in some treated patients. It is important for physicians using PDT to exercise caution in distinguishing between choroidal neovascular membranes and vitelliform lesions because the outcome in this latter group may be worse with application of PDT than with the natural course.

Prevalence of patients presenting with neovascular age-related macular degeneration in an urban population.

Purpose: To determine the number and type of new cases of neovascular age-related macular degeneration (AMD) present in a defined urban population and to establish the proportion that would be recommended for treatment with verteporfin or laser photocoagulation. Methods: Patients referred to an ophthalmic center in Vienna during a 10-week period because of recent deterioration in vision caused by newly diagnosed neovascular AMD were included. Results: Neovascular AMD was diagnosed in 168 eyes in 153 patients. One hundred one eyes (60.1%) had lesions that were occult with no classic choroidal neovascularization (CNV); of these, 70 were subfoveal, 19 were juxtafoveal, and 12 were extrafoveal. Thirty-five eyes (20.8%) had predominantly classic lesions; of these, 27 were subfoveal, 6 were juxtafoveal, and 2 were extrafoveal. Thirty-two eyes (19.0%) had minimally classic lesions, of which 31 were subfoveal and 1 was extrafoveal. In accordance with consensus guidelines from a panel of experts and with American Academy of Ophthalmology’s Preferred Practice Pattern guidelines, 33 lesions (17%) would be considered for treatment with verteporfin therapy. A further 37 subfoveal lesions with occult with no classic CNV and 7 juxtafoveal lesions with occult with no classic CNV might also benefit from verteporfin therapy if there is evidence of presumed recent disease progression. Five lesions (3.0%) could have been treated with laser photocoagulation according to Macular Photocoagulation Study criteria. Conclusions: These results suggest that verteporfin therapy substantially increases the number of patients with treatable neovascular AMD.