Clinicopathological findings of choroidal neovascularisation following verteporfin photodynamic therapy

Choroidal infarction after photodynamic therapy combined with bevacizumab and triamcinolone reversed by tissue plasminogen activator: case report

PURPOSE

To present a case of choroidal infarction after combined therapy of photodynamic therapy, intravitreal bevacizumab, and sub-Tenon triamcinolone injection salvaged by tissue plasminogen activator administration.

METHODS

Interventional case report.

RESULTS

Combined therapy of full-fluence photodynamic therapy, intravitreal bevacizumab, and sub-Tenon triamcinolone injection was given on the same day to treat neovascular age-related macular degeneration in an 82-year-old patient. Subsequent acute visual loss and marked macular edema as a result of choroidal infarction were noted. Intravitreal and sub-Tenon administration of tissue plasminogen activator were performed 9 days later to salvage the choroidal infarction, and visual improvement was noted. Fundoscopy and optical coherent tomography showed almost complete resolution of macular edema. Indocyanine green angiography revealed reperfusion of the choroidal vessels.

CONCLUSION

Choroidal infarction may happen after combined therapy. Tissue plasminogen activator administration may reverse the infarction and help visual recovery.

Choroidal neovascularization in pathological myopia

Myopic choroidal neovascularization (CNV) is one of the leading causes of visual impairment worldwide. The clinical and socioeconomic impact of myopic CNV in Asian countries is particularly significant due to rising trend in the prevalence and severity of pathological myopia. The exact pathogenesis of myopic CNV remains unclear and there is paucity of information with respect to incidence and risk factors for myopic CNV from prospective studies. Furthermore, there are no recognized measures that may prevent or delay the development of CNV in eyes with pathological myopia. Advances have been made in the diagnosis and characterization of myopic CNV over the years. Until recently, treatment modalities for myopic CNV were limited to thermal laser photocoagulation and photodynamic therapy with verteporfin, both these modalities primarily aim at prevention of further visual loss. In the last 5 years, inhibitors of vascular endothelial growth factor (VEGF) have been used successfully and may improve vision to some extent. Nevertheless, the long-term safety and efficacy of anti-VEGF agents remains unknown. Furthermore, the risk of developing chorioretinal atrophy remains the key factor in determining the final visual outcome. This review article summarizes the current literature on myopic CNV, highlighting new evolving diagnostic and treatment modalities, prognostic factors influencing visual outcome, and areas of future research.

Severe decrease in visual acuity with choroidal hypoperfusion after photodynamic therapy

Background

Photodynamic therapy (PDT) is considered a selective method of treatment which works in areas of choroidal neovascularization (CNV); however, there are reports of choroidal hypoperfusion after PDT. This paper presents a clinical case of choroidal circulation disturbances caused by PDT, accompanied by CNV progression.

Case Report

The patient, a 75-year-old woman, was qualified for PDT in the right eye – first treatment due to progression of occult CNV. Best corrected visual acuity (BCVA) in the right eye at baseline was +0.3 logMAR. After PDT, a rapid decrease in visual acuity to +0.7 logMAR in the right eye was observed, central choroidal hypoperfusion in fluorescein angiography (FA) with subretinal fluid appeared and, as a consequence, progression of neovascular age-related macular degeneration (AMD). After stabilizing the local state through conservative therapy, a decision was made to treat the right eye with intravitreal injections of vascular endothelial growth factor (VEGF) inhibitor. During a 12-month period of observation, 7 doses of ranibizumab were administered. A regression in activity of wet AMD was observed, with visual acuity of +0.6 logMAR.

Conclusions

Choroidal circulation disturbance after PDT is possible and has to be taken into account. Sporadically, it can lead to an acute decrease in visual acuity and local state. After stabilization of AF and optical coherence tomography imaging, further treatment of neovascular AMD with intravitreal injections of anti-VEGF agents should be considered.

Lucentis using Visudyne study: determining the threshold-dose fluence of verteporfin photodynamic therapy combined with intravitreal ranibizumab for exudative macular degeneration

Purpose

Combination verteporfin photodynamic therapy (vPDT) and antivascular endothelial growth factor (anti-VEGF) therapy may decrease the need for injections while maintaining visual acuity in exudative age-related macular degeneration. This pilot study was designed to determine the threshold fluence dose of vPDT (the dose required to demonstrate an effect on choroidal perfusion) combined with ranibizumab.

Methods

Seven patients were randomized to sham vPDT (two patients), 20% fluence vPDT (two patients), or 40% fluence vPDT (three patients) in combination with three-monthly intravitreal 0.5 mg ranibizumab injections. Intravitreal ranibizumab was reinjected if disease activity was seen on fluorescein angiography, optical coherence tomography, or clinical examination. Indocyanine green-determined choroidal hypoperfusion was graded in a masked fashion.

Results

Patients with 20% vPDT had mild hypoperfusion defects at seven days that resolved by week 4 (threshold dose); patients with 40% fluence vPDT had marked hypoperfusion at seven days that persisted as long as 12 months. Recruitment was stopped after limited efficacy was observed. One patient with 20% fluence vPDT lost 19 letters at one year; no other patient lost or gained >10 letters. Central retinal thickness decreased in six of seven patients, but ranibizumab injections did not decrease.

Conclusion

This pilot study shows that the threshold fluence dose of vPDT (when combined with ranibizumab) is approximately 20% standard fluence, and that mild and transient choroidal hypoperfusion can occur. Forty percent fluence vPDT causes a more prolonged and striking hypoperfusion. Despite hypoperfusion, no decrease in visual acuity or injections required was noted, suggesting that even higher fluence levels of vPDT may be necessary to decrease the number of anti-VEGF injections.

A high-throughput biophotonics instrument to screen for novel ocular photosensitizing therapeutic agents

PURPOSE

High-throughput techniques are needed to identify and optimize novel photodynamic therapy (PDT) agents with greater efficacy and to lower toxicity. Novel agents with the capacity to completely ablate pathologic angiogenesis could be of substantial utility in diseases such as wet age-related macular degeneration (AMD).

METHODS

An instrument and approach was developed based on light-emitting diode (LED) technology for high-throughput screening (HTS) of libraries of potential chemical and biological photosensitizing agents. Ninety-six-well LED arrays were generated at multiple wavelengths and under rigorous intensity control. Cell toxicity was measured in 96-well culture arrays with the nuclear dye SYTOX Green (Invitrogen-Molecular Probes, Eugene, OR).

RESULTS

Rapid screening of photoactivatable chemicals or biological molecules has been realized in 96-well arrays of cultured human cells. This instrument can be used to identify new PDT agents that exert cell toxicity on presentation of light of the appropriate energy. The system is further demonstrated through determination of the dose dependence of model compounds having or lacking cellular phototoxicity. Killer Red (KR), a genetically encoded red fluorescent protein expressed from transfected plasmids, is examined as a potential cellular photosensitizing agent and offers unique opportunities as a cell-type-specific phototoxic protein.

CONCLUSIONS

This instrument has the capacity to screen large chemical or biological libraries for rapid identification and optimization of potential novel phototoxic lead candidates. KR and its derivatives have unique potential in ocular gene therapy for pathologic angiogenesis or tumors.

Verteporfin combination regimens in the treatment of neovascular age-related macular degeneration

BACKGROUND

Neovascular age-related macular degeneration is characterized by choroidal neovascularization that has a complex pathogenesis. Combining agents that have different mechanisms of action (i.e., verteporfin photodynamic therapy, antivascular endothelial growth factor, and/or anti-inflammatory therapies) could maximize clinical benefits through potential complementary effects. This review discusses findings from studies investigating this hypothesis.

METHODS

Articles were retrieved from PubMed using relevant search terms. Abstracts from recent scientific meetings and details of ongoing trials from clinicaltrials.gov were also included.

RESULTS

Following its approval, verteporfin was important in the management of choroidal neovascularization due to age-related macular degeneration for several years. Improved visual outcomes have now been reported with antiangiogenic agents (e.g., intravitreal ranibizumab), especially when frequently administered. Results from investigator-sponsored trials, retrospective case studies and Registries, which have provided insights into the latest findings from clinical practice in the "real-world" setting, as well as randomized controlled trials, suggest that a combination approach is generally well tolerated and may maintain improvements in visual and anatomic outcomes with fewer retreatments.

CONCLUSION

A rationale exists for investigating combination approaches to target different processes in choroidal neovascularization pathogenesis, which may optimize treatment benefits in neovascular age-related macular degeneration. Encouraging data suggest that combination strategies are not associated with major adverse events.

The role of vascular endothelial growth factor and other endogenous interplayers in age-related macular degeneration

Age-related macular degeneration (AMD) is a multifaceted disease characterized by early subclinical changes at the choroidea-retinal pigment epithelium interface. Both the causal and formal pathogenesis of the disease is still puzzling. Similarly, the reason for progression into two distinct late forms which are "geographic atrophy" and "choroidal neovascularization" remains enigmatic. Late changes are usually responsible for the dramatic loss in central function that has a devastating effect on quality of life. In industrialized countries the disease is a major cause for visual disability among persons over 60 years of age. Due to demographic right-shift and increased life expectancy, AMD is not only a medical problem but will have a pronounced socio-economic effect. Neovascular AMD with the development of choroidal neovascularization in the macular area accounts for 80% of the severe loss of visual acuity due to AMD. In the last decades, treatment modes were merely based on the destruction or surgical removal of the neovascular complex. In the present, however, the philosophical approach to treat the disease is changing to a pathology modifying manner. Intelligent targeting of the involved relevant factors and pathways should stop disease progression, reduce complications and improve vision. The first step into this new era has been accomplished with the introduction of antiangiogenic agents. The new agents act either directly on vascular endothelial growth factor (VEGF) or indirectly on its functional cascade. VEGF makes a fundamental contribution to neovascular processes but it also acts in physiological pathways. The main purpose of this review is to summarize its physiological role especially within the eye, the role in the development of AMD and to understand and foresee both the benefits and potential side-effects of the anti-VEGF-based therapy.

Video monitoring of neovessel occlusion induced by photodynamic therapy with verteporfin (Visudyne), in the CAM model

The aim of the present study was to monitor photodynamic angioocclusion with verteporfin in capillaries. Details of this process were recorded under a microscope in real-time using a high-sensitivity video camera. A procedure was developed based on intravenous (i.v.) injection of a light-activated drug, Visudyne^®, into the chorioallantoic membrane (CAM) of a 12-day-old chicken embryo. The effect of light activation was probed after 24 h by i.v. injection of a fluorescent dye (FITC dextran), and analysis of its fluorescence distribution. The angioocclusive effect was graded based on the size of the occluded vessels, and these results were compared with clinical observations. The time-resolved thrombus formation taking place in a fraction of the field of view was video recorded using a Peltier-cooled CCD camera. This vessel occlusion in the CAM model was reproducible and, in many ways, similar to that observed in the clinical use of verteporfin. The real-time video recording permitted the monitoring of platelet aggregation and revealed size-selective vascular closure as well as some degree of vasoconstriction. Platelets accumulated at intravascular junctions within seconds after verteporfin light activation, and capillaries were found to be closed 15 min later at the applied conditions. Larger-diameter vessels remained patent. Repetition of these data with a much more sensitive camera revealed occlusion of the treated area after 5 min with doses of verteporfin and light similar to those used clinically. Consequently, newly developed light-activated drugs can now be studied under clinically relevant conditions.

Histopathological findings in postmortem eyes after photodynamic therapy for choroidal neovascularisation in age-related macular degeneration: report of two cases

BACKGROUND

To report the histopathological findings after photodynamic therapy (PDT) in eyes obtained postmortem with choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD).

METHODS

Two eyes were obtained postmortem from two patients with CNV secondary to AMD. Both of the patients had been treated with PDT. Serial sections through the posterior poles were obtained and stained with haematoxylin-eosin, periodic acid-Schiff, Masson trichrome or phosphotungstic acid haematoxylin (PTAH). Two-dimensional reconstructions were prepared and compared with fluorescein angiograms.

RESULTS

The interval between PDT and death was 3 months and 17 months in each patient, respectively. Light-microscopic examination showed that CNV enveloped with retinal pigment epithelium (RPE) in both eyes. The average size of the CNV was 550 x 280 microm. One eye had combined (subRPE/subretinal) growth pattern CNV, and the other eye had both type I (subRPE) and combined growth pattern CNV. All specimens contained fibrous proliferation and patent vascular channels within the CNV, and there was no thrombus formation within the vascular channels. No apparent abnormalities in the choroid were observed by light microscopy.

CONCLUSIONS

Although involution with fibrous tissue proliferation occurred, PDT did not result in permanent occlusion of the vascular channels in the CNV. Our findings indicate that PDT may accelerate involution of CNV, thus limiting its size and preserving photoreceptors.

Intravitreal bevacizumab (Avastin) in combination with verteporfin photodynamic therapy for choroidal neovascularization associated with age-related macular degeneration (IBeVe Study)

BACKGROUND

A novel alternative for combined treatment using verteporfin photodynamic therapy (PDT) has emerged as preliminary safety and efficacy data of the intravitreal use of the anti-angiogenic bevacizumab became available. In the current study we investigate the feasibility of intravitreal bevacizumab combined with verteporfin PDT for the treatment of choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).

METHODS

A single-centre, prospective, open-label study of 11 patients with documented CNV progression after PDT treatment who underwent combined PDT and intravitreal injection of 1.5 mg of bevacizumab was undertaken. Standardized ophthalmic evaluation was performed at baseline and at weeks 1, 2, 12 and 24. Clinical evidence of complications and changes in logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) using Early Treatment Diabetic Retinopathy Study (ETDRS) charts and in fluorescein leakage from CNV were evaluated.

RESULTS

The mean (+/-SD) age of the 11 patients was 74 (+/-5) years. Seven eyes had been treated with one previous PDT session and four eyes had two previous PDT sessions. The mean baseline logMAR ETDRS BCVA was 1.031 (Snellen equivalent, 20/200(-2)). At follow-up weeks 1, 2, 12 and 24, the mean logMAR ETDRS BCVA (Snellen equivalent) was 0.944 (20/160(-2)), 0.924 (20/160(-1)), 0.882 (20/160(+1)), and 0.933 (20/160(-2)), respectively. The change in BCVA from baseline was significant at each study follow-up interval (P < or = 0.001); at 12 and 24 weeks, the mean change in BCVA from baseline was an improvement of 1.49 and of 0.98 ETDRS line, respectively. Fluorescein leakage from CNV was absent in all eyes at week 12. One additional treatment session was required in seven (63.6%) eyes at week 24 due to recurrent fluorescein leakage from CNV ("minimum" [<50% of the leaking area noted at baseline], n = 4; and "moderate" [>50% of the leaking area noted at baseline], n = 3). No progression of the neovascular lesion was observed at week 24. No safety issues were identified throughout the period of the study.

CONCLUSIONS

The overall changes in vision and fluorescein leakage from CNV throughout the study suggest that a possible synergistic effect may arise from the combination of intravitreal bevacizumab with verteporfin PDT for the treatment of neovascular AMD.

Combined photodynamic therapy and intravitreal triamcinolone injection for the treatment of choroidal neovascularisation secondary to pathological myopia: a pilot study

Intravitreous triamcinolone associated with PDT should preferably be used among elderly patients who usually show lower visual acuity and a poorer response to PDT, or among patients with recurrent or greater CNVs

Photodynamic therapy of experimental choroidal neovascularization in the mouse

PURPOSE

To evaluate the qualitative and quantitative effects of verteporfin photodynamic therapy (PDT) on laser-induced choroidal neovascularization (CNV) in the mouse.

METHODS

PDT was applied to the normal mouse fundus using light doses of 32, 64, and 83 s, and histological analysis of the treated areas was performed. CNV was induced using krypton laser photocoagulation of the fundus, and the CNV lesions were subsequently treated with PDT using light doses of 32, 64, and 83 s. Enucleated eyes were analyzed with light and transmission electron microscopies, and measurements of CNV size were done on histologic sections and on isolectin B4-stained choroidal flat mounts.

RESULTS

PDT induced a light dose-dependent damage to the surrounding neural retina in normal eyes. At a light dose of 32 s, minimal damage was detected in the neural retina, whereas higher light doses caused distortion and disruption of the outer and inner nuclear layers and of the retinal pigment epithelium. When PDT was applied over laser-induced CNV lesions, the relative height of the lesions was significantly reduced (p < 0.05) using all light doses. Transmission electron microscopy 1 day after PDT treatment revealed occlusion of many of the CNV vessels. One week after PDT treatment, the CNV lesions contained patent vessels irrespective of light dose applied. Accordingly, PDT treatment inhibited (p < 0.05) but did not halt CNV lesion growth.

CONCLUSIONS

PDT treatment of laser-induced CNV may create an acute occlusion of neovessels and an inhibition of CNV lesion growth without apparent injury to the surrounding neural retina. However, PDT-treated areas will remain vascularized with continued growth of the CNV lesion, which in turn may explain the often limited effect of PDT in patients with neovascular age-related macular degeneration. Elevating the PDT light dose will not increase the treatment effect substantially but may lead to increased collateral injury.

Verteporfin photodynamic therapy induced apoptosis in choroidal neovascular membranes

AIM

To evaluate the impact of verteporfin photodynamic therapy (PDT) on the induction of apoptosis in choroidal neovascular membranes (CNV) secondary to age related macular degeneration.

METHODS

Retrospective review of 22 surgically excised CNV. 12 of these patients had been treated with PDT 3-146 days previously. Apoptotic cells were detected with the TUNEL technique and compared to the expression of CD34 (endothelial cells, EC), CD105 (activated endothelial cells), Ki-67 (proliferation marker), and cytokeratin18 (retinal pigment epithelial cells, RPE).

RESULTS

CNV excised 3 days after PDT were characterised both by collapsed and patent vessels. The EC displayed a statistical significant positive TUNEL reaction when compared to the remaining treated CNV (p < 0.001) and untreated CNV (P = 0.002). The proliferative activity was reduced. CNV excised 1-5 months after PDT displayed a patent vascularisation and high proliferative activity. All membranes either treated or untreated disclosed only sporadic TUNEL positive cells within the stroma and the RPE.

CONCLUSIONS

Verteporfin PDT leads to selective and effective damage of EC within CNV. Both patent and occluded vessels were lined by apoptotic EC. This finding and the increased expression of proliferation marker at later time points suggest that revascularisation after PDT is caused by angiogenesis rather than recanalisation.

Wirkt sich Acetylsalicylsäure negativ auf die photodynamische Therapie aus?

BACKGROUND

Non-thermal photodynamic therapy (PDT) is presently being used for the treatment of certain forms of age-related macular degeneration (AMD). This therapy results in selective occlusion of newly growing vessels. Due to this effectiveness of PDT the question came up whether inhibitors of platelet aggregation have an influence on PDT.

PATIENTS AND METHODS

Our retrospective study included 60 patients with mainly classic subfoveal choroidal neovascularizations (CNV) due to AMD. All patients were treated by PDT. Thirty patients took acetylsalicylic acid (aspirin) because of their general disease before and during treatment. In the control group none of the patients took acetylsalicylic acid.

RESULTS

Best corrected visual acuity and measured dimension of the choroidal neovascularization showed before beginning PDT no statistically significant difference (visual acuity p=0.676; dimension of CNV p=0.678). Also no significant difference existed between visual acuity (p=0.412; p=0.226; p=0.969) and CNV (p=0.871; p=0.245; p=0.323) at the follow-up examination.

CONCLUSION

Our study has shown that acetylsalicylic acid does not have any effect on PDT treatment.

Treatment of age-related macular degeneration

Age-related macular degeneration (AMD) is the greatest cause of legal blindness in the western world. Established treatments include argon laser photocoagulation of extrafoveal choroidal neovascularisation (CNV) and photodynamic therapy of selected sub-foveal CNV. Newer approaches are targeting the angiogenic pathway in CNV development. Currently, other treatment modalities, such as radiotherapy and transpupillary thermotherapy do not have a clear role to play. Surgical options are experimental and only available in some centres for selected patients. Prevention of AMD remains elusive. Dietary supplements may have a role, while statins and prophylactic laser photocoagulation of drusen remain experimental. This paper explains the principles behind these approaches.

Immunohistopathologic evaluation of choroidal neovascular membranes following verteporfin-photodynamic therapy

PURPOSE

To evaluate the vascularization and proliferative activity in choroidal neovascular membranes due to age-related macular degeneration after verteporfin photodynamic therapy and submacular removal.

DESIGN

Interventional case series.

METHODS

In a retrospective review of seven patients who underwent removal of subfoveal classic choroidal neovascular membranes after treatment with photodynamic therapy 3 to 146 days earlier, membranes were stained for CD 34, CD 105, and Ki-67 and correlated with clinical pictures and fluorescein angiography.

RESULTS

Fluorescein angiography performed on the day of surgery disclosed nonperfusion of the treated area 3 days after photodynamic therapy, but perfusion and leakage were seen at greater post-photodynamic therapy intervals. Membranes excised 3 days after photodynamic therapy showed CD34 and CD105 positive, mostly occluded vessels. The endothelial cells appeared damaged. Ki-67 activity was low. In membranes excised 34 to 146 days after photodynamic therapy, all vessels appeared patent and were lined by healthy endothelial cells with strong expression of CD34 and CD105. Ki-67 expression was elevated after 34 days but decreased thereafter.

CONCLUSION

Photodynamic therapy did not cause a general or complete occlusion of vessels within the choroidal neovascular membranes, as suggested by fluorescein angiography 3 days postintervention, but the endothelial cells appeared to be severely damaged. Proliferative activity within these specimens was reduced. At longer intervals after photodynamic therapy, the fibrovascular tissue seemed to recover; perfusion, hyperfluorescence, and leakage of the choroidal neovascular membranes could be detected by fluorescein angiography. The clinical appearance showed a correlation with the immunohistologic characteristics of an increased proliferative activity and patent vascularization.