Verteporfin photodynamic therapy in the rat model of choroidal neovascularization: angiographic and histologic characterization

PURPOSE: To develop a model of verteporfin photodynamic therapy (PDT) for experimental choroidal neovascularization CNV in the rat. METHODS: A laser injury model was used to induce experimental CNV in rats. The transit and accumulation of the photosensitizer verteporfin was assessed angiographically in CNV lesions, to determine the optimal time for delivery of light energy. The CNV lesions were then treated with verteporfin PDT, with two doses of verteporfin (3.0 and 6.0 mg/m(2)) and four activating doses of light energy (10, 25, 50, and 100 J/cm(2)). Closure of the CNV was assessed both angiographically and histologically. Verteporfin PDT was also performed on areas of normal choroid and retina at the two verteporfin doses and four light energy doses. The effect of these treatments on these structures was also assessed angiographically and histologically. RESULTS: Peak verteporfin intensities in the CNV were detected at 15 to 20 minutes after intravenous injection. Rates of closure of the CNV varied as a function of the dose of verteporfin and of the activating light energy. Angiographic closure of the CNV correlated with damage to the neovascular complex, as seen with light and electron microscopy. Damage to areas of normal choroid and retina treated with verteporfin PDT also varied as a function of the verteporfin and light energy doses. CONCLUSIONS: Verteporfin PDT for experimental CNV in the rat is a feasible, effective, and reproducible model that can be used for testing the efficacy of adjunctive therapy to verteporfin PDT.     

应用血啉单醚光动力疗法治疗角膜新生血管的研究

目的观察应用血啉单醚行光动力疗法(PDT)治疗角膜新生血管的效果。设计前瞻性随机对照实验。研究对象成年有色兔18只。方法制作碱烧伤角膜新生血管模型。血啉单醚5mg/kg静脉注射,不同能量密度(7.6￣152.8J/cm2)的氩绿激光照射角膜新生血管根部,不注射血啉单醚只单纯行同等能量密度的激光照射组作为对照组。主要指标PDT的能量密度,行角膜新生血管荧光素造影观察新生血管封闭情况。结果PDT后3天,角膜新生血管荧光素血管造影显示:应用61.2J/cm2及以上的能量,有67%以上的眼角膜新生血管被完全封闭,33%的眼部分有效。PDT后1周,61.2J/cm2及以上组仍有66.7%(16/24眼)的眼角膜新生血管完全封闭。激光后1个月5/24眼无新生血管出现,其余眼再次出现新生血管。结论采用激光能量密度在(61.2￣152.8)J/cm2照射的PDT治疗能完全或部分封闭兔碱烧伤角膜新生血管模型中的角膜新生血管,但有新生血管再生。(眼科,2006,15:180-183)     

Photodynamic therapy of corneal neovascularization with verteporfin

PURPOSE: To describe the effect of photodynamic therapy (PDT) using verteporfin (Visudyne) on corneal neovascularization (CNV) in two patients. METHODS: Two patients with corneal neovascularization were treated with a nonthermal laser light at 689 nm delivered 15 min after an intravenous infusion of verteporfin. Postoperative outcome of neovascularization was followed clinically (inflammation, intraocular pressure, and visual acuity) and photographically [color photographs and corneal fluorescein and indocyanine green (ICG) angiography] for a minimum of 6 months. RESULTS: Successful photothrombosis of corneal neovascularization was obtained immediately after treatment in the two patients, and regression was verified by corneal fluorescein and ICG angiography. In one case, partial vessel recanalization was observed after 1 month, and treatment was repeated, with complete regression of new vessels. No relevant side effects were observed in our cases. CONCLUSIONS: PDT with verteporfin is an effective and safe procedure indicated for patients with corneal neovascularization; however, multiple sessions may be required.     

光动力学疗法治疗角膜新生血管后角膜的光电镜改变

目的观察应用国产光敏剂行光动力学疗法(PDT)治疗角膜新生血管后角膜的组织学改变。方法碱烧伤有色兔角膜制作角膜新生血管模型。血啉单醚5mg/kg自耳缘静脉注射,不同的能量密度61.2-52.8J/cm2的氲绿激光照射角膜新生血管根部,不注射血啉单醚并单纯行同等能量密度的激光照射组作为对照组,PDT治疗后3h、1周、1个月行角膜光电镜检查。结果PDT后3h可见角膜急性炎症反应,有大量中性粒细胞浸润和少量嗜酸性白细胞浸润,虹膜组织无损伤。PDT后1周角膜炎症反应大部分消失,可见新生血管腔内有无定形物质填塞和许多影子血管。透射电镜显示:PDT组角膜新生血管内皮细胞内线粒体显示出空泡样变,细胞形态不完整。结论血啉单醚作为光敏剂,应用氩绿激光对角膜新生血管行PDT治疗,导致新生血管内皮细胞损伤,能有效封闭角膜新生血管,对周围组织无明显损伤。     

维替泊芬介导的光动力疗法治疗兔眼角膜新生血管

目的:旨在探讨和评估光敏剂维替泊芬(vertporfin)介导的光动力疗法(PDT)对角膜新生血管(CoNV)治疗的效果。方法:新西兰白兔随机分为2组:两组采用角膜基质层缝线的方法诱导CoNV形成。Ⅰ组行vertporfin-PDT治疗CoNV,verteporfin以1.5mg/kg静注。Ⅱ组不治疗,为阳性对照。治疗后裂隙灯显微镜观察CoNV变化并记录面积,取处理组及对照组的角膜、虹膜睫状体组织,行组织病理学检查,免疫组织化学(SABC法)检测血管内皮生长因子(VEGF)在角膜组织中的表达。结果:治疗后3d;1,2wk,Ⅰ组CoNV面积均明显小于Ⅱ组(P<0.01)。组织病理学检查显示,Ⅰ组CoNV管壁破坏,形成血栓。VEGF的表达Ⅰ组明显低于Ⅱ组(P<0.01)。结论:Vertporfin-PDT对兔模型眼CoNV有明显的抑制作用,不损伤邻近的正常血管及组织。     

Verteporfin photodynamic therapy for anterior segment neovascularization secondary to ischaemic central retinal vein occlusion

Purpose: To evaluate the efficacy of photodynamic therapy (PDT) with verteporfin for anterior segment neovascularizations (ASNVs) in patients affected by ischaemic form of central retinal vein occlusion (CRVO). Methods: Prospective non‐comparative case series including 10 consecutive patients (10 eyes) affected by ischaemic CRVO. Main outcome measure was the obliteration of ASNV. Results: One month after PDT, biomicroscopic examination showed partial obliteration of iris new vessels and complete closure of angle neovascularization. Iris fluorescein angiography performed 1 week after treatment showed partial closure of the iris new vessels with no evidence of leakage in the late phases. During the subsequent examinations, a partial reopening of the iris and angle new vessels in association with dye leakage on fluorescein angiography was evident. In any case, the fluorescein leakage turned out to be still reduced with respect to the baseline aspects. Conclusions: Our results show that PDT with verteporfin can partially obliterate ASNVs in eyes affected by ischaemic CRVO preventing from the evolution towards advanced stages of neovascular glaucoma, but is not effective in cases with complete angle synechial closure.     

Investigating the effect of ciliary body photodynamic therapy in a glaucoma mouse model

PURPOSE: To investigate the morphologic and functional effects of verteporfin ciliary body photodynamic therapy (PDT) in a murine glaucoma model and normal mouse eyes. METHODS: A glaucomatous mouse strain, DBA/2J and a normal control mouse strain (C57BL/6) were used in the study. Verteporfin was injected intravenously at doses of 1.0 (DBA/2J) or 2.0 or 4.0 (C57BL/6) mg/kg. Transscleral irradiation of the ciliary body was performed with light at a wavelength of 689 nm delivered through an optical fiber, with irradiance of 1800 mW/cm2 and fluence of 100 J/cm2. Laser irradiation was applied for 360 degrees of the corneoscleral limbus in C57BL/6 normal mice and for 180 degrees in DBA/2J mice. Retreatment was performed in C57BL/6 normal mice that had been treated with 2.0 mg/kg of verteporfin at post-PDT day 7. One eye of each animal was treated, and the fellow eye served as the control. The morphologic effect of PDT on the ocular structures was assessed by light and electron microscopy. The IOP was measured using an applanation tonometer with a fiber-optic pressure sensor. Surviving retinal ganglion cells (RGCs) in DBA/2J mice eyes were retrogradely labeled with a neurotracer dye at 12 weeks after PDT. RESULTS: In all groups, almost all ciliary body blood vessels in the treated area were thrombosed 1 day after PDT. In DBA/2J mice, ciliary epithelium and stroma were severely damaged 1 day after PDT. The mean IOP in treated eyes was significantly reduced compared with that in the control eyes in all groups. The reduction of mean IOP in DBA/2J mouse eyes persisted for 7 weeks, although the mean IOP in normal mouse eyes treated with 2 or 4.0 mg/kg verteporfin returned to the level of the fellow control eyes by 7 and 17 days after treatment, respectively. The mean number of RGCs in the DBA/2J treated eyes was significantly higher than in control eyes. CONCLUSIONS: Ciliary body PDT resulted in morphologic changes in the ciliary body, significant reduction of IOP, and prevention of ganglion cell loss in a mouse glaucoma model. These results suggest that ciliary body PDT is a more selective cyclodestructive technique with potential clinical application in the treatment of glaucoma.     

Treatment of rubeosis iridis with photodynamic therapy with verteporfin--A new therapeutic and prophylactic option for patients with the risk of neovascular glaucoma?

Patients with ischaemic retinopathy who show iris neovascularization despite panretinal laser photocoagulation (PRP) very often develop a neovascular glaucoma. Photodynamic therapy (PDT) has been shown to occlude neovascularization without damage to physiologic vessels or adjacent tissue in the treatment of choroidal neovascularization (CNV) and might also be of value for patients with neovascular glaucoma who did not benefit from the PRP. First results of a monocentre, open label, intra-individual controlled, pilot phase I/II, dose-finding study demonstrate that PDT with verteporfin is capable of occluding neovascular vessels for a defined period of time without damaging adjacent tissue or physiologic iris vessels. Whether this vessel occlusion will have an impact on the progression of rubeosis or neovascular glaucoma will be the subject of further investigation.     

Simultaneous but not prior inhibition of VEGF165 enhances the efficacy of photodynamic therapy in multiple models of ocular neovascularization

PURPOSE: To investigate the effect of the combined treatment of photodynamic therapy and specific VEGF165 inhibition with pegaptanib sodium (Macugen; Eyetech Pharmaceuticals, Lexington, MA) on ocular neovascularization. METHODS: Photodynamic therapy's (PDT's) effects on the integrity of pegaptanib sodium were analyzed by HPLC, a VEGF165-binding assay, and a VEGF165-induced tissue factor gene expression assay. The effects of mono- or combined treatment on vessel growth and regression were determined in a murine corneal neovascularization model. The effects of combined treatment on vessel growth were also determined in a murine choroidal neovascularization model. RESULTS: PDT did not affect the chemical composition of pegaptanib sodium nor the efficacy of pegaptanib sodium in the inhibition of VEGF165 binding to Flt-1 and VEGF165-induced gene expression. In an animal model of effects on existing ocular neovascular lesions (corneal neovascularization), PDT monotherapy yielded an initial regression of these vessels, but there followed a rapid regrowth. In contrast, pegaptanib sodium monotherapy yielded little regression but potently abrogated further vessel growth. The combination of pegaptanib sodium and PDT resulted in the regression of the neovascular lesions, as observed with PDT alone, but also prevented significant vessel regrowth, leading to a significantly greater reduction in lesion size than did each monotherapy. In addition, there was a significantly greater effect of the combination of pegaptanib sodium and PDT on lesion size in choroidal neovascularization than with each monotherapy. Pretreatment with pegaptanib sodium appeared to decrease the efficacy of PDT-induced vessel regression in corneal neovascularization, and as such the enhanced efficacy over monotherapy when the agents were delivered simultaneously was not observed. CONCLUSIONS: Although the combined simultaneous treatment of ocular neovascularization with PDT and pegaptanib sodium may provide a more effective approach for the regression and overall treatment of CNV associated with AMD, the order of addition of these treatments may play a role in achieving optimal efficacy.     

Panretinal photocoagulation and photodynamic therapy for anterior segment neovascularization secondary to ischemic central retinal vein occlusion.

BACKGROUND AND OBJECTIVE: To compare the effects of panretinal photocoagulation (PRP) and photodynamic therapy (PDT) for anterior segment neovascularization secondary to ischemic central retinal vein occlusion (CRVO). PATIENTS AND METHODS: Fifty-seven eyes were randomized to receive standard PRP (19 eyes), selective PRP (20 eyes), or PDT (17 eyes). Selective PRP was performed only when iris neovascularization and/or angle neovascularization showed progression on weekly follow-up. Primary outcome measures were the extension of anterior segment neovascularization and the rate of neovascular glaucoma development. Secondary outcome measures included visual acuity results. RESULTS: After 12 months of follow-up, iris neovascularization extension was 0.52, 2.55, and 2.27 in the PRP, selective PRP, and PDT groups, respectively. Anterior segment neovascularization extension was 0.57, 1.50, and 1.27 in the PRP, selective PRP, and PDT groups, respectively. Both showed a statistically significant difference in the PRP group. The rate of neovascular glaucoma development was similar in the three groups. CONCLUSIONS: Although PRP was better at determining iris neovascularization and anterior segment neovascularization regression, the similar rate of neovascular glaucoma development found in the three groups indicates that anterior segment neovascularization secondary to ischemic CRVO can also be safely managed using selective PRP or PDT.     

Phase I clinical trial results of verteporfin enhanced feeder vessel therapy in subfoveal choroidal neovascularisation in age related macular degeneration

AIMS: To investigate the safety and effectiveness of extrafoveal photodynamic therapy (PDT) occlusion of feeder vessels (FVs) in patients with subfoveal choroidal neovascularisation (CNV) as a result of age related macular degeneration. METHODS: FVs were identified using dynamic fluorescein and indocyanine green angiography with scanning laser ophthalmoscope. The standard doses of verteporfin and laser wavelength were used. The light dose was escalated by increasing the duration of the light dose so the light regimen was 50 J/cm2 for patients 1 and 2; 100 J/cm2 for patients 3, 4, 5; 125 J/cm2 for patients 6 and 7; and 150 J/cm2 for patients 8 and 9. Patients were examined at weeks 1, 4, and 12. RESULTS: The mean improvement on EDTRS chart 3 months after treatment was an increase of 2.1 lines (p = 0.07). Closure of the FV was achieved angiographically in three eyes at various light doses, in three eyes the FV was hypoperfused, and in three eyes the vessels were were neither closed nor hypoperfused. At the last follow up all FVs were reperfused. There was no evidence of retinal damage. CONCLUSION: Verteporfin enhanced FV therapy does not cause subfoveal retinal damage and may have potential to improve central vision in subfoveal CNV caused by exudative macular degeneration. It is not recommended as a monotherapy for CNV.     

Corneal neovascularization treated with argon laser.

The argon laser set at 50 mum, 100-150 mW, o-2 s occluded corneal blood vessels in pigmented Dutch rabbits provided the corneal responsible for inducing vascularization was inactive. After arterial treatment with the argon laser retrograde flow in untreated veins was demonstrated by fluorescein angiography. Therefore all corneal new vessels should be treated, not just arteries. Minimal iris damage complicated the laser therapy, but this was not thought necessarily to contraindicate the use of the argon laser to treat corneal blood vessels in man. The iris damage was associated with outpouring of aqueous from the ciliary processes, and it took up to a week for the blood-aqueous barrier to return to its normal state.     

Photodynamic therapy with verteporfin for anterior segment neovascularizations in neovascular glaucoma

PURPOSE: To evaluate photodynamic therapy (PDT) with verteporfin for iris and angle neovascularization in eyes with neovascular glaucoma. DESIGN: Interventional case series. METHODS: A prospective, noncomparative case series included four patients (four eyes) with neovascular glaucoma. PDT was performed following the parameters of treatment of age-related macular degeneration with photodynamic therapy Study Group (TAP). The laser was directed at the anterior chamber angle and iris surface using a Goldmann three-mirror contact lens. Iris and angle neovascularization were quantified using the number of clock hours involved. Outcome measures were obliteration of neovascularization and decrease of intraocular pressure (IOP). RESULTS: One week after PDT, we registered complete obliteration of angle neovascularization and partial occlusion of iris neovascularization. Subsequent reopening of angle neovascularization was detectable at 1 month. Intraocular pressure diminished considerably after 1 week, with a subsequent tendency toward stabilization. CONCLUSIONS: Photodynamic therapy can be used safely and effectively in the early phases of neovascular glaucoma to achieve angle neovascularization obliteration and IOP reduction.     

Influence of treatment parameters on selectivity of verteporfin therapy

PURPOSE: To improve selectivity of verteporfin therapy (PDT) in neovascular age-related macular degeneration (AMD) using modified treatment parameters. METHODS: Nineteen consecutive patients with predominantly classic choroidal neovascularization (CNV) in AMD were treated with 6 mg/m2 verteporfin given as bolus infusion. Patients received PDT with a fluence of either 25 or 50 J/cm2. Choroidal perfusion changes were evaluated by indocyanine green angiography (ICGA) at baseline, day 1, week 1, week 4, and month 3. Secondary outcomes were CNV closure rate and therapy-induced leakage documented by fluorescein angiography (FA). The safety of the treatment was assessed with ETDRS visual acuity. RESULTS: Complete CNV closure was achieved in all patients at day 1. Choroidal hypoperfusion was minimal in eyes treated with a reduced fluence of 25 J/cm2. Most patients treated with 50 J/cm2 showed significant choriocapillary nonperfusion at week 1, lasting as long as 3 months. A transient PDT-induced increase in leakage area in FA at day 1 was found to be more extensive in the 50-J/cm2 group. CONCLUSIONS: Bolus administration of verteporfin combined with a reduced light dose achieved improved selectivity of photodynamic effects, avoiding collateral alteration of the physiologic choroid while obtaining complete CNV closure. An increased selectivity with decreased effect on the surrounding choroid should be of advantage in verteporfin monotherapy as well as in combination strategies.     

Photodynamic therapy for corneal neovascularization using polymeric micelles encapsulating dendrimer porphyrins

PURPOSE: To investigate the accumulation of new photosensitizers (PSs), dendrimer porphyrin (DP, free DP), and DP encapsulation into polymeric micelles (DP-micelle) and the efficacy of photodynamic therapy (PDT) in an experimental corneal neovascularization model in mice. METHODS: Corneal neovascularization was induced by suturing 10-0 nylon 1 mm away from the limbal vessel in C57BL6/J mice. To determine the accumulation of free DP and DP-micelle, 10 mg/kg free DP or DP-micelle was administered by intravenous injection 4 days after suture placement. Mice were killed 1, 4, 24, and 168 hours after the injection of PS. Twenty-four hours after the administration of free DP or DP-micelle, mice were treated with a diode laser of 438-nm wavelength at 10 or 50 J/cm(2). Fluorescein angiography was performed before and 7 days after irradiation, and the area of corneal neovascularization was quantified. RESULTS: Free DP and DP-micelle accumulated in the neovascularized area 1 hour to 24 hours after administration. Fluorescence of DP was weaker than that of DP-micelle. Neither DP-micelle nor DP could be detected in normal limbal vasculature. In the PDT experiments using PS, mean residual rates of corneal neovascularization were 10.1% in the mice treated with DP-micelle and 21.6% in the mice treated with free DP at 10 J/cm(2) (P < 0.01). At 50 J/cm(2), mean residual rates of corneal neovascularization were 10.6% in the mice treated with DP-micelle and 13.7% in the mice treated with free DP (P > 0.05). Although corneal neovascularization in PDT-treated mice exhibited significant regression compared with the control group, significant energy-related vessel regression with increasing laser energy could not be observed. CONCLUSIONS: PDT with DP-micelle and free DP can provide efficacious treatment of corneal neovascularization.     

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.     

Verteporfin therapy for choroidal hemangioma: a long-term follow-up

BACKGROUND: To document the long-term follow-up of patients with circumscribed choroidal hemangioma who were treated with verteporfin photodynamic therapy (PDT). METHODS: Fifteen patients were included in a prospective interventional case series. Verteporfin PDT as a bolus infusion of 6 mg/m body surface area and a light dose of 100 J/cm at 689 nm applied over 166 seconds were administered. Standardized evaluation was performed every 3 months within the first year and at 12-month intervals during follow-up. RESULTS: At baseline, all patients presented with significant vision loss ranging from 20/26 to 20/500. During a mean follow-up of 36.6 months (range, 12-66 months), no patient had evidence of recurrence. Mean final visual acuity ranged from 20/20 to 20/400. In all patients, complete and permanent regression with no signs of tumor regrowth or recurring subretinal fluid was found. Of 15 patients, 13 had a substantial increase in visual acuity (range, 2-9 lines), and 2 patients' visual acuity remained stable. Chorioretinal atrophy at the previous tumor site did not enlarge over time. Retreatments after completion of the primary treatment were not necessary. CONCLUSION: Persistent and complete absence of choroidal hemangioma associated with persistent improvement in visual acuity and central visual fields can be obtained with verteporfin PDT.     

Sequence of early vascular events after photodynamic therapy

PURPOSE: To identify early vascular changes in choroidal neovascularization (CNV) and in adjacent normal choroid, after photodynamic therapy (PDT). METHODS: In a prospective study, 40 patients with predominantly classic CNV due to age-related macular degeneration (AMD) were treated with PDT performed with verteporfin. Verteporfin was administered intravenously at a dose of 6 mg/m(2) body surface area. A near infrared laser light dose of 50 J/cm(2), an irradiance of 600 mW/cm(2) and a wavelength of 692 nm was applied. A scanning laser system was used to perform confocal fluorescein angiography (FA) and indocyanine green angiography (ICGA) before treatment and regularly at 5 hours, 1 day, 1 week, and 3 months after PDT. Images were analyzed for CNV size and leakage area as seen by FA and ICGA. Collateral damage within the surrounding choroid was documented based on the hypofluorescence in early- and late-phase ICGA. RESULTS: No immediate occlusion of the CNV complex was found angiographically, but a dynamic change over time was observed in the early perfusion patterns and late-phase hyper- and hypofluorescence. At 5 hours after treatment, large portions of the CNV lesion were still perfused. One day after PDT, CNV size in early FA and early ICGA reached its minimum, at 0.49 mm(2) (15.7%) and 0.78 mm(2) (31.1%) of the initial area, respectively. In late-phase FA and ICGA, however, an immediate massive exudation with a continuous increase in hyperfluorescence originated from the CNV and surrounding choroid, with a maximum in leakage area at 1 day. At 1 week PDT-induced exudation slowly resolved. Eyes in 36 patients showed some choroidal hypofluorescence by ICGA before treatment. A progressive increase of the hypofluorescent area surrounding the CNV was observed, which correlated with the size of the laser spot. Maximum hypofluorescence was noted at 1 week with an average size of 11.1 mm(2) in early- and late-phase ICGA. CONCLUSIONS: In contrast to findings in experimental animals, PDT in humans with classic CNV did not induce immediate thrombosis, but primarily caused a breakdown of vascular barriers. A characteristic sequence of vascular changes was observed with early, enhanced leakage from the CNV and normal choroid followed by nonperfusion later. Occlusion of the CNV lesions occurred 1 day after treatment, but closure of the adjacent choroidal vessels proceeded slowly over as long as 1 week.     

Treatment parameters for selective occlusion of experimental corneal neovascularization by photodynamic therapy using a water soluble photosensitizer, ATX-S10(Na)

Time dependent change of an accumulation of an amphiphilic photosensitizer, ATX-S10(Na) on rabbit corneal neovascularization (CoNV) was evaluated by angiography using ATX-S10(Na) as a fluorescent dye on three rabbits. The angiography showed that the dye accumulated on CoNV 3-5 hr after dye injection when the dye in the iris was minimum. The results suggested 3-5 hr after might be the optimal time to start photodynamic therapy (PDT) to occlude CoNV selectively without damage to the surrounding normal tissue such as the iris. Then the optimal treatment parameters in PDT using ATX-S10(Na) for selective occlusion of the CoNV were investigated on rabbit eyes. PDT was performed with two different time intervals between dye injection and laser irradiation of a diode laser (670 nm), different laser doses and three different dye doses on 21 animals. PDT performed immediately after dye injection selectively occluded CoNV with laser irradiations from 30.6 to 38.2 J cm(-2)and a 2 mg kg(-1)dose of ATX-S10(Na), as well as with 15.3 J cm(-2)and a 6 mg kg(-1)dose. PDT performed 4 hr after dye injection with 107.0-152.8 J cm(-2)and a 6 mg kg(-1)dose, as well as with 38.2-53.5 J cm(-2)and a 12 mg kg(-1)dose was also effective. Although PDT performed either immediately or 4 hr after ATX-S10(Na) injection selectively occluded CoNV, the width of the optimal range of radiant exposures seemed wider in PDT performed 4 hr after dye injection. It is supposed that this result is associated with the difference of dye accumulation between in CoNV and in normal tissue as shown by the present angiographical findings.     

Photodynamic therapy induces caspase-dependent apoptosis in rat CNV model

PURPOSE: To investigate the mechanism of cell death in laser-induced choroidal neovascularization (CNV) after photodynamic therapy (PDT). METHODS: PDT was performed in Brown-Norway rats using laser light at a wavelength of 689 nm, irradiance of 600 mW/cm(2), and fluence of 25 J/cm(2) after intravenous injection of verteporfin at the doses of 3, 6, and 12 mg/m(2). Apoptotic cells in CNV were detected by TUNEL assay at 1, 3, 6, 15, 24, and 48 hours after PDT. Caspase activation at 1, 3, 6, 15, and 24 hours after PDT was determined by immunohistochemistry (IHC) with a cleaved caspase-3 or -9 antibody. Akt activity was determined by Western blot and IHC with a phosphorylated-Akt (pAkt) antibody. To investigate the roles of Akt in PDT-induced apoptosis, insulin-like growth factor (IGF)-1, an Akt activator, with or without wortmannin, an inhibitor of PI3K-Akt pathway, was injected into the vitreous before PDT. RESULTS: The number of TUNEL-positive cells in CNV increased at 3 hours after PDT and peaked at 6 hours, showing a dose dependence of verteporfin. Caspase activation was detected in TUNEL-positive cells. Dephosphorylation of Akt in CNV occurred within 1 hour. IGF-1 significantly activated Akt and suppressed the number of TUNEL-positive cells in CNV, and the effects of IGF-1 were diminished by wortmannin. CONCLUSIONS: PDT induced caspase-dependent apoptosis in CNV. These results suggest that PDT leads to dephosphorylation of Akt and subsequent activation of the caspase-dependent pathway. Understanding the intracellular signaling mechanisms of apoptosis in PDT may lead to more selective and effective treatment of CNV secondary to age-related macular degeneration.