Threshold power levels for NPe6 photodynamic therapy

OBJECTIVE: To determine the threshold power levels for producing retinal and choroidal vascular occlusion using mono-L-aspartyl chlorin e6 (NPe6) photodynamic therapy; to evaluate its efficacy with longer intervals between photosensitizer injection and laser application; to determine the elapsed time between light application and appearance of angiographic changes. METHODS: Pigmented and nonpigmented rabbits were injected intravenously with 2 mg/kg of NPe6 before laser irradiation of the retina-choroid. Group 1 was treated at increasing power levels; fluorescein angiograms were obtained at each fluence. Group 2 animals were exposed to laser irradiation at 5 minutes, and 1 and 3 hours postinjection to determine (by fluorescein angiography 24 hours post-treatment) if increasing the interval affected outcome. Group 3 animals underwent fluorescein angiography at 30 minutes, 1 hour, 2 hours, and 24 hours posttreatment to document the time between laser application and subsequent vessel closure. RESULTS: Choroidal vessel occlusion was angiographically evident in all lesions at fluences of > or = 2.65 J/cm2 in pigmented rabbits and at > or = 0.88 J/cm2 in nonpigmented rabbits. Lesion diameter decreased as the time between injection and treatment increased. Vessel occlusion was documented at least 2 hours after treatment. CONCLUSION: Choroidal vessel occlusion can occur at very low fluence.     

Photodynamic therapy of experimental choroidal neovascularization with a hydrophilic photosensitizer: mono-L-aspartyl chlorin e6

PURPOSE: To demonstrate the selective localization of the hydrophilic photosensitizer mono-L-aspartyl chlorin e6 (NPe6) in experimental choroidal neovascularization in nonhuman primate eyes. METHODS: Sixty-seven experimental choroidal neovascular lesions (CNV) were created in the fundi of Macaca monkeys using the modified Ryan's model and documented by fluorescein and indocyanine green angiography. To determine the biodistribution of NPe6 and the optimal timing of laser irradiation after dye administration, NPe6 angiography and fluorescence microscopy with NPe6 were performed. Photodynamic therapy (PDT) was performed at various dye doses (0.5-10.0 mg/kg) and laser fluences (7.5-225.0 J/cm2) on the CNV and on 10 areas of normal retina and choroid. Treatment outcomes were assessed by fluorescein and indocyanine green angiography and confirmed by light and electron microscopy. RESULTS: NPe6 fluorescence microscopy demonstrated intense fluorescence of CNV and retinal pigment epithelial cells. Choroidal vessel walls and outer retina adjacent to CNV fluoresced moderately; retinal vessel walls and microcapillaries had trace fluorescence. The fluorescence of CNV lesions on fluorescein angiography became stronger than that of retinal vessels 20-60 minutes after dye injection. Choroidal neovascular lesion closure was achieved with NPe6 PDT without significant damage to the sensory retina. Histology demonstrated necrosis of CNV endothelial cells with minimal damage to surrounding tissues. CONCLUSIONS: NPe6 PDT selectively localizes to experimental CNV in nonhuman primates, resulting in occlusion of CNV with sparing of the neurosensory retina.     

Angiographic and histologic effects of fundus photodynamic therapy with a hydrophilic sensitizer (mono-L-aspartyl chlorin e6).

PURPOSE: To demonstrate the efficacy of the photosensitizer mono-L-aspartyl chlorin e6 (NPe6) in closing choroidal vessels at low energy levels, that tissue uptake and clearance are rapid, and that low concentrations of drug are needed to achieve clinical effects. DESIGN: Experimental animal study. ANIMALS: Pigmented rabbits and Japanese monkeys were used in this study. METHODS: Using a modified 664-nm diode laser, the fundi of pigmented rabbits and Japanese monkeys were irradiated after intravenous administration of NPe6 (2-100 mg/kg). Time from injection to irradiation varied from 5 to 15 minutes, and duration of exposure varied from 1 to 10 seconds. Power output at the corneal surface was either 3.6 or 5.9 mW. Animals were examined by indirect ophthalmoscopy and fluorescein angiography at 2 hours and 7 days after treatment. After enucleation 7 days after treatment, specimens were prepared for light and electron microscopy. MAIN OUTCOME MEASURES: Angiographic evidence of occlusion and histopathologic evidence of retinal damage. RESULTS: Both clinical and histopathologic examination demonstrated effects on the choroidal vasculature and the retinal pigment epithelium, including necrosis of endothelial cells and occlusion in choroidal vessels, particularly within the choriocapillaris, at low energy levels. Overlying neurosensory retina was minimally affected. Fluorescein angiography of lesions treated with 2 mg/kg and laser fluence of 2.3 to 7.5 J/cm2 showed a normal appearance 2 hours after treatment, which changed to early hypofluorescent and later hyperfluorescent lesions 7 days after treatment. In contrast, those animals receiving the 10-mg/kg dose and laser fluence of 0.46 to 0.75 J/cm2 showed marked hypofluorescence of choroidal lesions and occlusion of retinal vessels 7 days after treatment. CONCLUSIONS: Effective occlusion of normal choroidal vessels was achieved at 2 mg/kg using 2.3 to 7.5 J/cm2 or at 10 mg/kg using 0.46 to 0.75 J/cm2 with minimal injury to overlying neurosensory retina.     

Retreatment effect of NPe6 photodynamic therapy on the normal primate macula

PURPOSE: To evaluate the safety and efficacy of repeated photodynamic therapy (PDT) with mono-L-aspartyl chlorin e6 (NPe6) on normal primate fovea and choroid. METHODS: Macaca fuscata monkeys were used as experimental subjects. Mono-L-aspartyl chlorin e6 at a dose of 2 mg/kg was administered by intravenous infusion. Laser irradiation was applied within 5 minutes using a 664-nm diode laser at a power output of 5.9 mW (750 mW/cm2), spot size of 1,000 microm, and time of 10 seconds. This resulted in a fluence of 7.5 J/cm2. Three consecutive PDT treatments at 2-week intervals were applied over the center of the fovea and posterior fundus near the arcade vessels of each eye. The animals were killed and the eyes were enucleated for histologic study 2 weeks after the last treatment. RESULTS: Limited changes could be observed in the sensory retina under light microscopy. Photoreceptor cells and outer segments were not damaged, even after repeated PDT. Proliferation and duplication of the retinal pigment epithelial cells were common findings. A plaque of fibrous tissue was present, interwoven with retinal pigment epithelial cells in eyes that received repeated PDT. The retinal vessels remained patent even after three sessions of PDT. However, occlusion of the choriocapillaris and the large choroidal vessels was observed after repeated PDT treatment. CONCLUSION: Repeated PDT of healthy nonhuman primate fundi using a hydrophilic photosensitizer (NPe6) shows preservation of the neurosensory retina components and architecture with damage confined to the retinal pigment epithelium and choriocapillaris.     

Transpupillary thermotherapy: effect of wavelength on normal primate retina

PURPOSE: To correlate changes in primate fundus after transpupillary thermotherapy (TTT) at two wavelengths. METHODS: Twelve primate eyes were treated with TTT using a wavelength of 635 nm (n=7) or 810 nm (n=5). Laser parameters were as follows: 635 nm (spot size, 1 mm; duration, 30-8 seconds; and fluence [power over time], 20-91.4 J/cm) and 810 nm (spot size, 2 mm; duration, 60 seconds; and fluence, 96-436 J/cm). Fundus photography, fluorescein and indocyanine green angiography, and enucleation were performed at time 0 or 2 weeks after TTT for histologic analysis. RESULTS: Threshold for fundus lesions (91.4 J/cm at 635 nm and 191 J/cm at 810 nm), acute and chronic retinal damage shown by histologic analysis (79.2 J/cm at 635 nm and 96 J/cm at 810 nm), and choroidal vessel occlusion (50 J/cm at 635 nm and 96 J/cm at 810 nm) were lower at 635 nm. Disorganization of the retina and retinal pigment epithelium was seen for both wavelengths at time 0 and 2 weeks after TTT. Occlusion of the choriocapillaris and choroidal stromal vessels was noted only in specimens obtained 2 weeks after TTT. CONCLUSIONS: TTT resulted in acute and delayed damage to the neurosensory retina that persisted at 2 weeks. The 635-nm wavelength demonstrated a lower threshold fluence for visible fundus lesions, retinal damage, and choroidal vascular occlusion than the 810-nm laser.     

Dose-related structural effects of photodynamic therapy on choroidal and retinal structures of human eyes

PURPOSE: To determine the effects of photodynamic therapy (PDT) on choroidal and retinal structures of human eyes. METHODS: One eye from each of three patients with large malignant melanomas of the uvea destined for enucleation received PDT using verteporfin according to the approved treatment recommendations for patients with age-related macular degeneration. Two laser spots and two light doses (50 J/cm(2) and 100 J/cm(2)) were applied in unaffected chorioretinal areas. The effects of PDT were assessed by fluorescein and indocyanine-green angiography. The eyes were enucleated 1 week later, fixed in buffered paraformaldehyde/glutaraldehyde solution, bisected along the laser spots, and processed for light and electron microscopy. RESULTS: In agreement with the clinical angiographic findings of hypofluorescence, a rather selective occlusion of the choriocapillary layer was observed in the 50-J/cm(2) PDT areas, whereas the 100-J/cm(2) PDT areas additionally revealed closure of deeper choroidal vessels and focal alterations of the retinal pigment epithelium. The overlying neurosensory retina, including photoreceptors and retinal capillaries, was well preserved in all PDT areas. Electron microscopy showed that alterations of the choriocapillary endothelium comprised swelling, shrinkage and fragmentation of endothelial cells, detachment from their basement membrane up to complete degeneration of the endothelial lining, leading to platelet aggregation, degranulation, and thrombus formation. Complete occlusion of capillary lumina by fibrin, thrombocytes, and cellular debris was observed. Remaining intact endothelial cells appeared to be reorganized into novel smaller vascular channels within occluded lumina. CONCLUSIONS: PDT with verteporfin at a dosage used clinically induces selective occlusion of the physiological choriocapillaris without affecting deeper choroidal, retinal, and optic nerve vessels or the overlying retinal pigment epithelium and neurosensory retina. The main mechanism of action appears to be vascular thrombosis induced by cytotoxic damage of endothelial cells and platelet activation. An increase in light dose enhances the occlusive effect with thrombosis within deeper choroidal layers and damage to the retinal pigment epithelium. However, photoreceptors remained intact at all light doses used.     

Evaluation of the new photosensitizer Stakel (WST-11) for photodynamic choroidal vessel occlusion in rabbit and rat eyes

PURPOSE: To evaluate the photodynamic potential of a new hydrosoluble photosensitizer (WST-11, Stakel; Steba Biotech, Toussus-Le-Noble, France), for use in occlusion of normal choroidal vessels in the rabbit eye and CNV (choroidal neovascularization) in the rat eye. METHODS: Occlusive and nonocclusive parameters of Stakel and verteporfin photodynamic therapy (PDT) were investigated in pigmented rabbits. Eyes were followed by fluorescein angiography (FA) and histology at various intervals after PDT. RESULTS: When occlusive parameters (fluence of 50 J/cm(2), 5 mg/kg drug dose and DLI [distance to light illumination] of 1 minute) were used, Stakel PDT was efficient immediately after treatment without associated structural damage of the RPE and retina overlying the treated choroid in the rabbit eye. Two days later, total occlusion of the choriocapillaries was seen in 100% of the treated eyes, along with accompanying histologic structural changes in the overlying retina. When the occlusive parameters (fluence, 100 J/cm2; drug dose, 12 mg/m2; and DLI, 5 minutes) of verteporfin PDT were used, occlusion of the choriocapillaries was observed in 89% of the treated eyes. Histology performed immediately after treatment demonstrated structural damage of the overlying retina and RPE layer. Weaker, nonocclusive Stakel PDT parameters (25 J/cm2, 5 mg/kg, and DLI of 10 minutes) did not induce choriocapillary occlusion or retinal lesions on FA or histology. Weaker, nonocclusive verteporfin PDT parameters (10 J/cm2, 0.2 mg/kg, and DLI of 5 minutes) did not induce choriocapillary occlusion. However, histology of these eyes showed the presence of damage in the retinal and choroidal tissues. Moreover, preliminary results indicate that selective CNV occlusion can be achieved with Stakel PDT in the rat eye. CONCLUSIONS: Unlike verteporfin PDT, Stakel PDT does not cause direct damage to the RPE cell layer or retina. These observations indicate that Stakel PDT may have a high potential for beneficial therapeutic outcomes in treatment of AMD.     

Choroidal neovascular membranes after photodynamic therapy: ultrastructural analysis of two surgically excised membranes

PURPOSE: To report on the ultrastructural electron microscopic findings of two surgically excised subfoveal choroidal neovascular membranes (CNV) that had undergone photodynamic therapy (PDT). METHODS: Two patients underwent PDT because of subfoveal neovascular membranes (CNV). Due to enlargement of the CNV seen on fluorescein angiography three months after PDT, one patient underwent surgical excision of the membrane; the other patient underwent both surgical membrane excision combined with macular translocation one month after PDT. The membranes were examined under the transmission electron microscope (TEM). RESULTS: The membranes were composed of a core and a rim, the latter being mainly composed of fibrin and collagen fibrils. The core was preeminently composed of endothelium-lined vascular channels associated with retinal epithelium cells. The endothelial cells of blood vessels appeared well-preserved. CONCLUSIONS: The lack of histological signs of recanalization and vascular thrombosis may indicate that in our cases the enlargement of the CNVs seen on fluorescein angiography three months and one month respectively after PDT may originate mainly from reproliferation of choroidal vessels rather than recanalization of previously occluded vessels.     

Effect of photodynamic therapy with ATX-S 10 (Na) on experimental choroidal neovascularization

PURPOSE: To evaluate an appropriate irradiative condition for selective occlusion of experimental choroidal neovascularization(CNV) with photodynamic therapy (PDT) using ATX-S 10 (Na). METHODS: Experimental CNV was induced in monkey eyes by laser photocoagulation. PDT(dose of irradiative energy 40 to 80J/cm2) was performed after 3.5 mg/kg of body weight intravenous injections of ATX-S 10(Na). CNV and retinal vessel occlusion induced by PDT was evaluated by fluorescein angiography (FA) at 1 and 7 days after irradiation. If FA showed no fluorescein dye leakage from CNV at 1 and 7 days after irradiation, CNV was evaluated by histopathological analysis at 7 days after irradiation. RESULTS: Within 30 to 33 minutes after ATX-S 10(Na) injection and irradiation with 50 to 60 J/ cm2, FA showed no fluorescein dye leakage from CNV and no closure of retinal vessels at 1 and 7 days after irradiation. Light micrographs showed occluded CNV, and retinal vessels remained patent and there was no apparent change in the inner layer of the retina. CONCLUSIONS: Irradiative condition of ATX-S10 (Na) 3.5 mg/kg was appropriate 30 to 33 minutes after ATX-S 10(Na) injection and irradiation with 50 to 60 J/cm2.     

PDT to monkey CNV with ATX-S10(Na): inappropriateness of early laser irradiation for selective occlusion

PURPOSE: There is controversy about which mode of laser irradiation, early irradiation with low-dose photosensitizer or late irradiation with high-dose, benefits the selective occlusion of choroidal neovascularization (CNV) in photodynamic therapy (PDT). In this study, using an amphiphilic photosensitizer, 13,17-bis (1-carboxypropionyl) carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyiminoethylidene-2,7,12,18-tetraethyl porphyrin sodium (ATX-S10(Na); Photochemical Inc., Okayama, Japan), photodynamic and adverse effects of early irradiation on CNV-bearing monkey eyes were investigated. METHODS: Experimentally induced CNV lesions and normal retina were irradiated with a diode laser (670-nm wavelength) at a dose of 1 to 90 J/cm(2) at 1 to 19 minutes after intravenous injection of 2 mg/kg body weight of ATX-S10(Na). Vascular occlusion and CNV recurrence were evaluated by fluorescein and indocyanine green angiography and histologic analysis, until 4 weeks after irradiation. RESULTS: Of 45 different conditions, 23 did not induce CNV closure, 20 provided both CNV occlusion and retinal vessel damage, and 2 achieved selective CNV occlusion without retinal vascular injury. Recurrence of CNV was induced in 19 of 22 CNV-occluding conditions. ATX-S10(Na) angiography showed that dyes were similarly distributed between normal vessels and CNV at early time periods after injection, whereas they were preferentially accumulated in CNV after 30 minutes. CONCLUSIONS: In PDT with ATX-S10(Na), irradiation within 20 minutes of dye injection failed to induce selective CNV occlusion, probably because there is no significant difference in the biodistribution of dye between CNV and retinal vessels. It also caused frequent CNV recurrence after extensive inflammation in the irradiated retina.     

BDNF reduces the retinal toxicity of verteporfin photodynamic therapy

PURPOSE: Verteporfin photodynamic therapy (PDT) is the most effective treatment for age-related macular degeneration, using laser activation of a photosensitizing dye to achieve closure of choroidal neovascularization. Although PDT preferentially affects pathologic vessels, it can also cause collateral damage to the overlying retina. In the current study, it was found that the neuroprotective agent brain-derived neurotrophic factor (BDNF) reduces this retinal damage. METHODS: Normal adult rats received intravitreal BDNF in one eye and PBS or no injection in the other eye 2 days before PDT. RESULTS: Control eyes exhibited choroidal hypofluorescence, moderate to severe photoreceptor loss, and depression of local retinal function measured using multifocal ERG in the laser-treated area. BDNF-injected eyes had more surviving photoreceptors and improved multifocal ERG responses 1 week after PDT. BDNF did not diminish the effect of PDT on the choroidal circulation as assessed by fluorescein angiography, and there was no evidence of retinal toxicity due to BDNF treatment. CONCLUSIONS: These results suggest that adjunctive neuroprotective therapy may reduce collateral damage to photoreceptors and improve visual outcome after PDT.     

Histological findings of a surgically excised myopic choroidal neovascular membrane after photodynamic therapy

Background The authors describe a myopic choroidal neovascular membrane excised 4 months after photodynamic therapy (PDT).Methods A 68-year-old woman with classic choroidal neovascularization (CNV) due to pathologic myopia underwent PDT with verteporfin in the left eye. Four months after treatment a full-thickness macular hole was diagnosed in the same eye and the patient underwent vitrectomy with submacular membranectomy. The subfoveal membrane was studied by light microscopy and immunohistochemical techniques.Results Light microscopy showed a thin fibrovascular membrane covered by residual retinal pigment epithelium. The membrane contained homogeneous matrix with small collagen bundles, fibroblasts and small blood vessels. The distribution of blood vessels was nonuniform: extravasated red blood cells, macrophages and other inflammatory elements were not present in the fibrous matrix. Endothelial cells were highlighted by CD34 immunostaining and did not show any significant alteration. There was no evidence of inflammatory cells or thrombosis inside vascular lumina.Conclusions Histologic examination of the neovascular membrane showed features similar to those of surgically excised myopic CNV without PDT treatment. Our findings suggest that PDT-induced occlusion is temporary. Fluorescein leakage from CNV after a single PDT treatment can be considered as an sign of blood vessel regrowth or recanalization indicating that multiple treatments are necessary.     

Photodynamic therapy of choroidal hemangioma: two case reports

Background: Photocoagulation, cryotherapy and radiotherapy have been used to treat angiomatous lesions. Depending on the location of the angioma, these treatments can cause additional, significant functional damage. Photodynamic therapy (PDT) however, allows a selective occlusion of vascular lesions without damaging adjacent retinal structures.  Methods: Two patients with isolated choroidal hemangiomas involving the posterior pole were treated with PDT. Treatments were performed using a diode laser at 692 nm, a light dose of 100 J/cm² and 6 mg/m² body surface area verteporfin (BPD-MA). PDT was applied in two courses in one eye and in four in the other eye at 1–4 months intervals. Patients were followed up for 9–12 months with visual acuity measurements and dilated ophthalmoscopy. Ultrasound, indocyanine green angiographic and fluorescein angiographic images were evaluated at each visit.  Results: Tumor heights were 3.3 and 4.6 mm on pretreatment ultrasound. After therapy, patients with isolated choroidal hemangioma showed total regression of the lesion and improved visual acuity due to resorption of retinal edema. Serous retinal detachment and cystoid macular edema resolved. Ultrasound demonstrated a progressive decrease in tumor height after each PDT application, with complete disappearance of the lesion. Retinal vessels were not affected by the treatment, and retinal function recovered in areas with previous tumor involvement.  Conclusion: PDT allows selective treatment of large intraocular angiomatous lesions.Without optimized parameters, complete regression of choroidal hemangiomas, resolution of secondary complications and improvement of visual acuity were documented. Received: 1 February 1999 Revised: 23 August 1999 Accepted: 6 September 1999     

Retinal vascular changes associated with transpupillary thermotherapy for choroidal melanomas

PURPOSE: To define retinal vascular changes after transpupillary thermotherapy (TTT) for choroidal melanomas and assess their clinical impact. METHODS: Stereoscopic fluorescein angiogram pairs of 29 patients pre- and post-treatment with TTT were examined for patterns of vascular damage, and the patients were studied for ensuing complications. RESULTS: Widespread retinal capillary loss was confined within the treatment margins except in cases of coexisting large retinal artery or vein occlusions. Artery occlusions occurred in 83%, involving a large artery in 23%. Venous occlusions occurred in 69%, involving large veins in 10%. Subretinal choroidal neovascularization occurred in four cases, in one causing hemorrhage that broke through into the vitreous. No retinal neovascularization occurred. Choroidal vasculature was relatively preserved at the periphery of the treated area. Foveal vascular damage caused visual loss in six cases. Vascular changes beyond the treatment margins did not affect the fovea in any case. Retinal fibrosis affected two cases. Diabetic patients fared no worse than healthy counterparts. CONCLUSIONS: Transpupillary thermotherapy produces characteristic retinal vascular changes that may reduce vision when affecting the fovea. Vascular changes are confined within the treatment margins except in cases of associated large vessel occlusion. There is a small risk of neovascularization, both retinal and choroidal.     

Acute visual loss and chorioretinal infarction after photodynamic therapy combined with intravitreal triamcinolone

PURPOSE: To report acute visual loss associated with dynamic vascular changes after photodynamic therapy (PDT) combined with intravitreal triamcinolone (IVTA) for the treatment of occult choroidal neovascularization (CNV). METHODS: An 86-year-old woman complained of visual loss in her left eye. Angiographic examination showed a serous pigment epithelium detachment complicated by CNV. She underwent combined treatment with IVTA (4 mg) followed by standard verteporfin PDT administered after a 5-day interval. RESULTS: The patient developed vision loss 1 day after PDT. Ophthalmoscopic examination disclosed an acute serous neurosensory retinal detachment. Fluorescein angiography showed a large area of early hypofluorescence in correspondence to and extending beyond the photodynamic spot. Neurosensory retinal vessels involvement with dilation of the retinal arterioles and capillary nonperfusion were also revealed. Indocyanine green angiography showed choroidal infarction within the collateral choroid included in the area of light exposure, with associated nonperfusion of medium and large choroidal vessels being revealed. Five days after PDT, spontaneous severe bleeding with breakthrough into the vitreous occurred, in addition to an RPE tear. CONCLUSIONS: Acute loss of vision associated with vascular changes in retinal and choroidal circulation represents an uncommon but serious complication following combined PDT and IVTA. These risks should be carefully considered in combination therapies.     

Mechanism of photodynamic occlusion using liposomal Zn(II)-phtalocyanine

PURPOSE: To evaluate the potential of liposomal Zinc(II)-phthalocyanine (ZnPc) to selectively target subretinal vasculature. METHODS: Photodynamic therapy (PDT) with liposomal Zinc(II)-phtalocyanine was used to induce choroidal occlusion in eyes of pigmented rabbits. Drug doses of 0.16, 0.24, 0.32, and 0.4 mg/kg body weight were administered. Photosensitization was performed at a wavelength of 671 nm and an irradiance of 100 mW/cm2 applying fluences of 5, 10, 20, and 50 J/cm2. RESULTS: Using liposomal ZnPc, occlusion of choroidal vessels was achieved without damage to the overlying neurosensory retina. A tight dose correlation was found with a drug dose of 0.32 mg/kg and a light dose of 10 J/cm2 inducing a selective thrombosis of the subretinal capillary layer. Histology revealed a selective intravascular alteration of the endothelial cells. CONCLUSIONS: PDT using liposomal ZnPc allows occlusion of subretinal vasculature with maintenance of neuroretina and RPE. The destructive effect on choroidal vascular endothelium is intensive.     

Histological findings of surgically excised choroidal neovascular membranes after photodynamic therapy

AIM: To investigate effects of photodynamic therapy (PDT) on human choroidal neovascularisation (CNV). METHODS: Two patients with recurrences after PDT with verteporfin underwent surgical extraction of the CNV. Immediately after surgical excision the subfoveal neovascular membranes were divided for light microscopic and for electron microscopic processing. For light microscopy tissues were embedded in paraffin. Sections were stained with haematoxylin and eosin, and the periodic acid Schiff (PAS) reaction was performed to determine histological diagnosis and to ensure tissue quality. For electron microscopy the specimens were fixed in glutaraldehyde and embedded in epoxy resin. Semithin sections were stained with uranyl acetate and lead citrate and examined with a transmission electron microscope. RESULTS: Light microscopy showed thick fibrovascular membranes in both cases. On the outer surface remnants of retinal pigment epithelial cells resting on thickened inner aspect of Bruch's membrane were found. On the retinal side some outer segments were found. The membrane showed areas with irregularly shaped vessels. Electron photomicrographs showed occluded vessels within the CNV containing thrombotic masses and/or ultrastructural damage of the neovascular endothelium. Most of the vessels presented regressive changes with vacuolisation and fragmentation of the neovascular endothelium accompanied by disintegration of the endothelial cell layer. Extravasation of red blood cells was observed. Occasionally, vessels with normal endothelium containing intact red blood cells were observed. Some vessels contained immature endothelial cells. At some locations the retinal pigment epithelium cells (RPE) were metaplastic showing highly vacuolised cytoplasm. CONCLUSIONS: These findings suggest that the evidence of fluorescein leakage from the CNV and enlargement of the neovascular complex following PDT could be related to new vessel growth and recanalisation of occluded vessels. Additionally, RPE disturbances were observed in the specimens. This finding may be related to the original pathology or could indicate that PDT treatment may result in RPE atrophy.     

Clinicopathologic studies of age-related macular degeneration with classic subfoveal choroidal neovascularization treated with photodynamic therapy

BACKGROUND: Photodynamic therapy (PDT) is a relatively new modality that is currently under clinical and experimental evaluation for treatment of subfoveal choroidal neovascularization (CNV). The authors report the case of an 82-year-old woman who underwent verteporfin-mediated PDT for classic subfoveal CNV. Fluorescein angiography performed 2 weeks after treatment disclosed reduction of the initial area of neovascularization and leakage by approximately 60%. Three weeks after PDT, however, the area of leakage was almost the same size as that before treatment. The patient underwent submacular membranectomy almost 4 weeks after treatment. The authors describe the ultrastructural vascular changes after PDT and a clinicopathologic study of classic CNV. METHODS: The submacular membrane was studied by light and electron microscopy and immunohistochemical techniques. RESULTS: Ultrastructural examination of the peripheral vessels showed evidence of endothelial cell degeneration with platelet aggregation and thrombus formation. Occasional occluded vessels were surrounded by macrophages, a phenomenon previously reported to describe the process of resorption of such blood vessels. The vessels in the center of the membrane were unremarkable. CONCLUSION: Photodynamic therapy causes endothelial cell damage, thrombus formation, and vascular occlusion of classic CNV in age-related macular degeneration.     

Combining surgical ablation of retinal inflow and outflow vessels with photodynamic therapy for retinal angiomatous proliferation

PURPOSE: To evaluate short-term efficacy of combining surgical ablation of retinal inflow and outflow vessels and photodynamic therapy (PDT) for stage 3 retinal angiomatous proliferation (RAP). DESIGN: Prospective interventional case series. METHODS: Five eyes (five patients) underwent surgical ablation of inflow and outflow vessels and PDT for stage 3 RAP. RESULTS: Inflow and outflow vessels were ablated in four eyes, and only inflow was ablated in one eye. In four eyes starting PDT within six weeks of surgical ablation, choroidal neovascularization (CNV) disappeared or shrank after one PDT session (three months follow-up). However, CNV enlarged again in three of the four (final follow-up) because of reperfusion from newly formed inflow vessels. In one eye starting PDT seven months after ablation, a new retinal inflow vessel feeding the CNV appeared by the time of the first PDT session. The CNV continued to expand, despite two PDT sessions. CONCLUSIONS: Combining surgical ablation and PDT was not useful on account of a high frequency of reperfusion from retinal inflow vessels.     

Choroidal vascular remodelling in central serous chorioretinopathy after indocyanine green guided photodynamic therapy with verteporfin: a novel treatment at the primary disease level

AIMS: To evaluate the changes in the choroidal vasculature in central serous chorioretinopathy (CSC) after photodynamic therapy (PDT) with verteporfin and to assess its potential role as a treatment option. METHODS: A prospective, non-comparative, interventional study was performed in eyes with persistent CSC or chronic CSC that had fluorescein leakage at the fovea. All eyes received one single session of PDT with verteporfin (6 mg/m2 body surface area) followed by application of 50 J/cm2 laser at 689 nm. The laser spot size was guided by findings in ICG-A. RESULTS: Six eyes from six patients with a mean follow up of 12.7 months were analysed. Narrowing of the original dilated choroidal vessels and decrease in extravascular leakage could be demonstrated in all (100%) PDT treated eyes. 3 months after PDT, the mean diameter of the dilated choroidal vessel reduced from 546 microm to 371 microm (p=0.028). Five (83%) patients had improvement in visual symptoms and best corrected visual acuity. Fluorescence leakage stopped at the 1 month follow up in five eyes (83%) and at 3 months in all six eyes (100%). One eye developed choroidal neovascularisation at 3 month follow up. There was no other serious ocular or systemic complication. CONCLUSIONS: PDT is successful in stopping the fluorescein leakage in all six patients without recurrence of CSC. The ICG-A findings of choroidal vascular remodelling and decreased choroidal permeability after PDT are encouraging. As the sample size is small and the mean follow up period is short, further trials of PDT with verteporfin for CSC are required to address the optimal parameters in ensuring longer term safety and efficacy outcome.