Treatment of subfoveal choroidal neovascularisation in age related macular degeneration: focus on clinical application of verteporfin photodynamic therapy

Verteporfin Photodynamic Therapy for the Treatment of Chorioretinal Conditions: A Narrative Review

Photodynamic therapy (PDT) with verteporfin involves intravenous administration of a photosensitizer followed by its laser light activation at the target site to inhibit aberrant choroidal vascularization. This narrative review provides an overview of the role verteporfin PDT plays in the management of chorioretinal conditions. A PubMed literature review of all English-language articles published through October 19, 2023, was conducted to identify relevant references. Verteporfin PDT has been shown to be safe and effective for the treatment of patients with choroidal neovascularization (CNV) due to neovascular age-related macular degeneration and is often used in combination with a vascular endothelial growth factor (VEGF) inhibitor. Additionally, patients with polypoidal choroidal vasculopathy, a subtype of neovascular age-related macular degeneration, also benefit from verteporfin PDT combined with a VEGF inhibitor for improving visual acuity. Verteporfin PDT has also been effective in treating patients with peripapillary CNV, as well as eyes with CNV due to ocular histoplasmosis and pathologic myopia. Reduced dose and/or fluence PDT protocols have been effective in patients with central serous chorioretinopathy while reducing adverse effects. In eyes with choroidal hemangioma, tumor regression and visual outcomes have been improved with verteporfin PDT treatment. Photodynamic therapy with verteporfin continues to play an important role in the management of chorioretinal conditions.

Application and investigation of thrombopoiesis-stimulating agents in the treatment of thrombocytopenia

Platelets, derived from a certain subpopulation of megakaryocytes, are closely related to hemostasis, coagulation, metastasis, inflammation, and cancer progression. Thrombopoiesis is a dynamic process regulated by various signaling pathways in which thrombopoietin (THPO)-MPL is dominant. Thrombopoiesis-stimulating agents could promote platelet production, showing therapeutic effects in different kinds of thrombocytopenia. Some thrombopoiesis-stimulating agents are currently used in clinical practices to treat thrombocytopenia. The others are not in clinical investigations to deal with thrombocytopenia but have potential in thrombopoiesis. Their potential values in thrombocytopenia treatment should be highly regarded. Novel drug screening models and drug repurposing research have found many new agents and yielded promising outcomes in preclinical or clinical studies. This review will briefly introduce thrombopoiesis-stimulating agents currently or potentially valuable in thrombocytopenia treatment and summarize the possible mechanisms and therapeutic effects, which may enrich the pharmacological armamentarium for the medical treatment of thrombocytopenia.

Sustained-Release Microspheres of Rivoceranib for the Treatment of Subfoveal Choroidal Neovascularization

The wet type of age-related macular degeneration (AMD) accompanies the subfoveal choroidal neovascularization (CNV) caused by the abnormal extension or remodeling of blood vessels to the macula and retinal pigment epithelium (RPE). Vascular endothelial growth factor (VEGF) is known to play a crucial role in the pathogenesis of the disease. In this study, we tried to repurpose an investigational anticancer drug, rivoceranib, which is a selective inhibitor of VEGF receptor-2 (VEGFR2), and evaluate the therapeutic potential of the drug for the treatment of wet-type AMD in a laser-induced CNV mouse model using microsphere-based sustained drug release formulations. The PLGA-based rivoceranib microsphere can carry out a sustained delivery of rivoceranib for 50 days. When administered intravitreally, the sustained microsphere formulation of rivoceranib effectively inhibited the formation of subfoveal neovascular lesions in mice.

Plasmonic Gold Nanostar-Enhanced Multimodal Photoacoustic Microscopy and Optical Coherence Tomography Molecular Imaging To Evaluate Choroidal Neovascularization

Although photoacoustic microscopy (PAM) and optical coherence tomography (OCT) allow visualization of the retinal microvasculature, distinguishing early neovascularization from adjacent vessels remains challenging. Herein, gold nanostars (GNSs) functionalized with an RGD peptide were utilized as multimodality contrast agents for both PAM and OCT. GNSs have great absorption and scattering characteristics in the near-infrared region where most vasculature and tissue generates a less intrinsic photoacoustic signal while having a small size, excellent biocompatibility in vivo, and great photostability under nanosecond pulsed laser illumination. This enabled visualization and differentiation of individual microvasculature in vivo using multimodal PAM and OCT imaging. Detailed three-dimensional imaging of GNSs was achieved in an important choroidal neovascularization model in living rabbits. Through the administration of GNSs, PA contrast increased up to 17-fold and OCT intensities increased 167%. This advanced molecular-imaging platform with GNSs provides a unique tool for detailed mapping of the pathogenesis of the microvasculature.

Long-Term Follow-up of Patients with Exudative Age-Related Macular Degeneration Treated with Intravitreal Anti-Vascular Endothelial Growth Factor Injections

PURPOSE

To determine the long-term visual outcomes and intravitreal injection burden of patients with exudative age-related macular degeneration (AMD) treated with intravitreal anti-vascular endothelial growth factor (VEGF) injections.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Patients with exudative AMD treated with intravitreal anti-VEGF injections with annual office visits for at least 7 years.

METHODS

Snellen visual acuity was measured at baseline and then annually until the last year of follow-up. The number of injections was recorded on an annual basis during each year of follow-up.

MAIN OUTCOME MEASURES

The change in the frequency of injections over time along with the change in visual acuity each year from the baseline visit through 7 years.

RESULTS

During this period, 533 eyes of 429 patients were treated for exudative AMD. Of these, 391 eyes (73%) met the inclusion criteria of annual office visits and received a mean of 5.8 ± 2.5 intravitreal injections per year. The baseline mean visual acuity was 0.6 ± 0.5 logarithm of the minimum angle of resolution (logMAR; Snellen equivalent, 20/80), and the 7-year visual acuity was 0.8 ± 0.6 logMAR (Snellen equivalent, 20/126; P < 0.0001). When compared with the 142 eyes that did not undergo an office visit for a continuous 12-month period, eyes with annual office visits showed similar baseline mean visual acuity (0.7 logMAR vs. 0.6 logMAR; P = 0.2102), but more injections per year (P < 0.0001). Of the 533 total eyes, 124 eyes (23%) maintained better than 20/40 visual acuity at 7 years. These eyes received more injections overall per year (6.5 vs. 5.5 injections per year; P = 0.0007).

CONCLUSIONS

In a real-world setting, eyes that maintained consistent, long-term follow-up received significantly more intravitreal injections per year than eyes with inconsistent follow-up. Eyes with 20/40 or better vision at study conclusion received more injections per year than eyes with worse than 20/40 vision.

Development of copolymeric nanoparticles of hypocrellin B: Enhanced phototoxic effect and ocular distribution

In the present work, we have developed a photosensitizer hypocrellin B (HB) and nano silver loaded PLGA-TPGS nanoparticles with improved singlet oxygen production for enhanced photodynamic effect for the efficient treatment of age related macular degeneration. Random copolymer (PLGA-TPGS) synthesized by ring opening and bulk polymerization was characterized by IR, ¹H NMR and TGA analysis. HBS-CP-NPs prepared by nanoprecipitation techniques were spherical shaped 89.6-753.6nm size particles with negative zeta potential. The average encapsulation efficiency was 84.06±11.43% and HB release from the HBS-CP-NPs was found to be biphasic with a slow release of 1.41% in the first 8h and 48.91% during 3days as measured by RP-HPLC. DSC thermograms indicate that HB was dispersed as amorphous form in HBS-CP-NPs. The ROS generation level of HBS-CP-NPs was significantly higher than that of HB/HB-CP-NPs. The production of ¹O₂ of HBS-CP-NPs has been assessed using EPR spectrometer. The ¹O₂ generating efficiency follows the order of nano silver>HB-CP-NPs>HBS-CP-NPs>pure HB drug solution. The superior phototoxic effect of HBS-CP-NPs (85.5% at 50μM) was attained at 2h irradiation in A549 cells. Significant anti angiogenic effect of HBS-CP-NPs was observed in treated CAM embryos. Following intravenous injection of HBS-CP-NPs to rabbits, the maximum amount of HB was found in retina (3h), iris (9h), aqueous humour (9h) and vitreous humour (9h).

25th RCOphth Congress, President's Session paper: 25 years of progress in medical retina

The quarter century since the foundation of the Royal College of Ophthalmologists has coincided with immense change in the subspecialty of medical retina, which has moved from being the province of a few dedicated enthusiasts to being an integral, core part of ophthalmology in every eye department. In age-related macular degeneration, there has been a move away from targeted, destructive laser therapy, dependent on fluorescein angiography to intravitreal injection therapy of anti-growth factor agents, largely guided by optical coherence tomography. As a result of these changes, ophthalmologists have witnessed a marked improvement in visual outcomes for their patients with wet age-related macular degeneration (AMD), while at the same time developing and enacting entirely novel ways of delivering care. In the field of diabetic retinopathy, this period also saw advances in laser technology and a move away from highly destructive laser photocoagulation treatment to gentler retinal laser treatments. The introduction of intravitreal therapies, both steroids and anti-growth factor agents, has further advanced the treatment of diabetic macular oedema. This era has also seen in the United Kingdom the introduction of a coordinated national diabetic retinopathy screening programme, which offers an increasing hope that the burden of blindness from diabetic eye disease can be lessened. Exciting future advances in retinal imaging, genetics, and pharmacology will allow us to further improve outcomes for our patients and for ophthalmologists specialising in medical retina, the future looks very exciting but increasingly busy.

Enhancing RPE Cell-Based Therapy Outcomes for AMD: The Role of Bruch's Membrane

Age-related macular degeneration (AMD) is the leading cause of legal blindness in older people in the developed world. The disease involves damage to the part of the retina responsible for central vision. Degeneration of retinal pigment epithelial (RPE) cells, photoreceptors, and choriocapillaris may contribute to visual loss. Over the past decades, scientists and clinicians have tried to replace lost RPE cells in patients with AMD using cells from different sources. In recent years, advances in generating RPE cells from stem cells have been made and clinical trials are currently evaluating the safety and efficiency of replacing the degenerated RPE cell layer with stem cell-derived RPE cells. However, the therapeutic success of transplantation of stem cell-derived RPE cells may be limited unless the transplanted cells can adhere and survive in the long term in the diseased eye. One hallmark of AMD is the altered extracellular environment of Bruch's membrane to which the grafted cells have to adhere. Here, we discuss recent approaches to overcome the inhibitory environment of the diseased eye and to enhance the survival rate of transplanted RPE cells. Our aim is to highlight novel approaches that may have the potential to improve the efficacy of RPE transplantation for AMD in the future.

Treatment of choroidal neovascularization due to angioid streaks: a comprehensive review

PURPOSE

To evaluate different therapies for choroidal neovascularization (CNV) due to angioid streaks (AS).

METHODS

Studies were identified by a systematic literature search and were included in the analysis based on predefined criteria. Primary outcome measure was change in best-corrected visual acuity (BCVA).

RESULTS

Fifty-four relevant studies were identified and included mostly uncontrolled case series. No randomized controlled trials were available. Treatment with vascular endothelial growth factor inhibitors improved or stabilized BCVA in all case series. Photodynamic therapy slowed down disease progression with stabilization or decrease of BCVA. Individual BCVA and follow-up data for each treated eye were reported in >160 cases for both treatments, vascular endothelial growth factor inhibitors and photodynamic therapy. In a pooled analysis of those studies, the difference of mean change in BCVA between both treatment groups was estimated as approximately 6 lines (0.59 logMAR [95% confidence interval, 0.38-0.8; P < 0.0001]). A better baseline BCVA was associated with a better BCVA outcome (P < 0.0001). Laser photocoagulation yielded comparable results as photodynamic therapy but application was mostly restricted to extrafoveal lesions, was complicated by frequent recurrences, and led to more retinal damage with subsequent absolute scotomas. Combination therapies seem to be not superior to monotherapy.

CONCLUSION

Intravitreal vascular endothelial growth factor inhibitors are currently the most effective treatment of CNV due to angioid streaks.

Effects of photodynamic therapy using hematoporphyrin monomethyl ether on experimental choroidal neovascularization

Hematoporphyrin monomethyl ether (HMME) is a novel and promising second-generation porphyrin-related photosensitizer for photodynamic therapy (PDT). To study the effects of HMME PDT on choroidal neovascularization (CNV) in rats, the PDT was performed 20 min after HMME bolus injection, which was investigated prior to the PDT by fluorescence microscopy with laser-induced CNV, and delivered at an irradiance of 400, 600 and 1000 mW cm(-2) corresponding to a fluence of 36, 54, 90 J cm(-2) in PDT plan I (15 mg kg(-1) HMME). In PDT plan II (30 mg kg(-1) HMME), the laser had a constant irradiance of 600 mW cm(-2), which was delivered for 60, 90 or 150 s, to also achieve total energy doses of 36, 54 or 90 J cm(-2). CNV closure rates assessed by fluorescein angiography and histologic damage to treated areas of choroid and retina varied as a function of the dose of HMME and of the activating light energy fluence. Endothelial cell labeled by platelet/endothelial cell adhesion molecule-1 presented treated CNV lesions that were significantly reduced in size (P < 0.01). It can be concluded that PDT using HMME can effectively occlude CNV. HMME is a potentially useful photosensitizer for the reduction in CNV size of irradiated areas.

[Towards a new treatment of retinoblastoma?]

Photodynamic therapy (PDT) is a recent approach for the treatment of small cancerous tumours, on-surface or accessible by endoscopy in which a dye (usually a tetrapyrrolic macrocycle) absorbs light and generates cytotoxic reactive oxygen species leading to cellular damage. Retinoblastoma (Rb) is a rare intraocular tumour of childhood. All the multifocal forms are hereditary and constitute a syndrome of genetic predisposition in the cancer. The current treatments with etoposide or carboplatine expose the patient to the late risk of second cancer. The use of PDT as cancer therapy is particularly attractive due to the use of few mutagenic and non-toxic photosensitizers (PS) prior light excitation and to the localized tumour illumination. The photoefficiency towards Rb of a glycoconjugated porphyrin is discussed and compared with the results obtained with a second-generation photosensitizer, the Foscan. Some in vivo results on an animal model of Rb are presented by a point of view of photoefficiency, biodistribution, pharmacokinetic and longitudinal follow-up of the PDT effect using a new non-invasive method of magnetic resonance imaging of real-time. Photodynamic treatments in association with non-invasive sodium imaging open ways for new treatment tailoring or treatment individualization of retinoblastoma in clinic.

Complete blood vessel occlusion in the chick chorioallantoic membrane using two-photon excitation photodynamic therapy: implications for treatment of wet age-related macular degeneration

Complete blood vessel occlusion is required for the treatment of age-related macular degeneration (AMD). AMD is the leading cause of blindness in developed countries and current treatment regimes have potential to cause collateral damage, or do not remove pre-existing unwanted vasculature. It has been proposed that two-photon excitation (TPE) photodynamic therapy (PDT) can be applied to cause local blood vessel occlusion without damaging surrounding retinal tissues. The in ovo chicken chorioallantoic membrane (CAM) is used as the model for vascularization in the wet form of AMD; novel techniques for the utilization of the CAM are reported. Complete occlusion of CAM vessels approximately 15 microm in diameter is achieved using the clinically approved photosensitizer Verteporfin (Visudyne, QLT, Incorporated, Vancouver, British Columbia, Canada) and TPE activation. The average and peak irradiances used for treatment are 3.3x10(6) Wcm(2) and 3.7x10(11) Wcm(2), respectively. A total fluence of 1.1x10(8) Jcm(2) is the dosage required for successful occlusion, and it is expected that for optimal conditions it will be much less. These results are the first proof-of-principle evidence in the literature that indicate TPE-PDT can be used to occlude small blood vessels. Further investigation will help determine the utility of TPE-PDT for treating wet AMD, perhaps through targeting feeder vessels.

Combination therapy for the treatment of ocular neovascularization

The growth of inappropriately regulated, leaky blood vessels is a prominent component of several debilitating eye diseases, such as age-related macular degeneration (AMD), proliferative diabetic retinopathy (PDR), and retinopathy of prematurity (ROP). New pharmacological therapies that target vascular endothelial growth factor-A (VEGF-A) have significantly enhanced the treatment of AMD by limiting the progression of the disease, and in some cases, by improving vision. Although anti-VEGF therapy will undoubtedly prove valuable in the treatment of other neovascular diseases of the eye, improvements with this type of therapy are still required. At present, anti-VEGF therapy requires intravitreal injection and a relatively frequent dosing regimen (4-6 weeks). Furthermore, in experimental models of neovascularization, anti-VEGF treatment becomes less effective at blocking vessel growth and at regressing vessels as the neovascularization develops over time. As such, the use of anti-VEGF therapy in late-stage AMD may be limited. An important strategy for improved treatment of neovascular diseases of the eye could be combination therapy. Combination therapy of anti-VEGF drugs with established treatments, such as photodynamic therapy with verteporfin (PDT-V), or with newly-developed drugs targeting specific kinases, presents opportunities for increased efficacy and improved therapeutic outcome. In this review, we evaluate the opportunities for combination therapy for the treatment of neovascular diseases of the eye.

Influence of photodynamic therapy for age related macular degeneration upon subjective vision related quality of life

BACKGROUND

Photodynamic therapy (PDT) has been used in the treatment of choroidal neovascularisation secondary to age-related macular degeneration (AMD). This study prospectively investigated patients' subjective change in visual function following PDT as treatment for AMD.

METHODS

Eighty-two consecutive patients receiving PDT in Tasmania, Australia, between May and November 2003 were recruited. In conjunction with a comprehensive clinical examination, the Visual Function-14 (VF-14) questionnaire was administered. Final follow-up occurred between February and March 2005. The VF-14 was scored by traditional summary scoring and by Rasch analysis.

RESULTS

Five of the 82 (6.1%) subjects recruited were excluded from analysis. PDT was performed on average 5.7+/-2.6 times per patient. Raw VF-14 scores tended towards being significantly lower at follow-up than at baseline (67.6+/-27.2 against 64.5+/-27.7; P=0.052), and did significantly deteriorate using a collapsed Rasch analysis (P=0.0102). Following treatment, 38 (47.5%) eyes had lost three or more Snellen lines of best-corrected visual acuity.

CONCLUSION

Patients undergoing PDT typically report reasonable visual function. In parallel with visual acuity, self-reported visual function may deteriorate slightly after PDT for AMD, but not as much as reported in untreated AMD.

Age-related macular degeneration

Images

Review of first year result of photodynamic therapy on age-related macular degeneration in chinese population

PURPOSE

To evaluate the effect of verteporfin therapy (Visudyne) on age-related macular degeneration (AMD) in Chinese patients. The baseline characteristic and the visual outcome will be compared with the treatment of AMD with photodynamic therapy study (TAP) and verteporfin in photodynamic therapy study (VIP).

DESIGN

Retrospective comparative case series.

METHOD

We recruited patients >50 years old, with best-corrected visual acuity >20/200 and fluorescein angiography documenting subfoveal either predominantly classic with greatest linear dimension <5400 mum or pure occult choroidal neovascularization (CNV) secondary to AMD. We applied non-thermal laser to the lesion 15 min after visudyne infusion as described in TAP study. Patients were followed up with fluorescein angiography every 3 months. Additional treatment would be offered if there was evidence of recurrence of CNV.

OUTCOME MEASURE

Baseline characteristic and visual outcome.

RESULT

In all, 46 eyes of 42 patients were enrolled at our centre from July 2002 to June 2003. They comprised 11 eyes with predominantly classic lesions and 35 eyes with pure occult lesion. The mean number of treatment sessions given was 2.9 in the first year. At the 12-month examination, there were 63 and 29% of patients showing visual improvement in predominantly classic and occult groups, respectively, while there were only 16% of patients in the TAP study and 12% of patients in the VIP study showing visual improvement in the same period.

CONCLUSION

Verteporfin therapy for subfoveal CNV is beneficial to Chinese patients with AMD at first year. The visual result seems to be better than that observed in Caucasian patients.

Prospective evaluation of digital non-stereo color fundus photography as a screening tool in age-related macular degeneration

PURPOSE

To evaluate mydriatic, non-stereo digital color fundus photographs as a screening tool for identifying and classifying exudative age-related macular degeneration (AMD).

DESIGN

Prospective case series.

METHODS

Digital color fundus photographs were obtained from patients seen in the AMD screening clinic over a 9-month period at the Ivey Eye Institute in London, Ontario. Photographs for eligible patients were separated by eye, cataloged, blinded, and randomly labeled before interpretation by an experienced vitreoretinal surgeon. Exact agreement, sensitivity, specificity, positive predictive value, and negative predictive value of the fundus photographs in diagnosing, classifying, and managing cases of suspected exudative AMD were then calculated against gold standard clinical examination and fluorescein angiography.

RESULTS

A total of 223 images were used from 118 eligible patients. Exact agreement between photographic evaluation and gold standard ranged from 89.2% (presence of pigment epithelial detachment (PED)) to 82.5% (evidence of retinal pigment epithelium geographic atrophy). Sensitivities ranged from 89.2% (presence of choroidal neovascular membrane (CNVM)) to 40.0% (presence of PED). Specificities ranged from 94.1% (presence of PED) to 86.8% (presence of retinal pigment epithelium geographic atrophy). Positive predictive value ranged from 86.1% (presence of CNVM) to 40.0% (presence of PED). Negative predictive value ranged from 94.1% (presence of PED) to 88.9% (presence of CNVM). As a screening tool for high-risk dry changes and active exudative changes, overall sensitivity specificity, positive predictive value, and negative predictive value were 82.1%, 79.1%, 70.4%, and 88.0%, respectively.

CONCLUSIONS

Digital, non-stereo color fundus photographs are highly sensitive and have high negative predictive value as a screening tool. Very few treatable lesions are missed using telemedicine in age-related macular degeneration.

The incidence and outcome of photodynamic therapy for macular degeneration in the Northern Region of the UK

PURPOSE

To assess the patients who have had photodynamic therapy (PDT) in the Northern region of the UK, in relation to the eligibility criteria found to benefit in the TAP study (treatment of age-related macular degeneration with photodynamic therapy study), so as to make an estimate of the number of patients who might benefit from this treatment and to present the outcome of the treatment so far.

METHOD

The records and fluorescein angiograms (FFAs) of all patients who had had PDT in the Northern region between 2001 and 2002 were reviewed for compliance with the TAP criteria of >50% classic choroidal neovascularization and >34 letters on the 2 m logMAR Early Treatment Diabetic Retinopathy Study chart. NHS funding has been available in the Northern Region since January 2001 for 'second eye' involvement. A review of all the angiograms performed for exudative macular degeneration in 1 year was also performed. The visual outcome of those patients 1 year from baseline was measured.

RESULTS

A total of 82 'second eye' patients were treated between January 2001 and December 2002. This gives an incidence of 65 per 3 million and so about 1300 in the whole of the UK (population 60 million). In all, 238 FFAs were performed on exudative macular degeneration, with 21% being found eligible for PDT. As of February 2003, 54 TAP criteria, macular degeneration patients were 1 year from initial treatment. Of these, 12 had incomplete follow-up and 13 patients had lost more than 15 letters. The responder rate defined as losing <15 letters was 42-13/42=69%. Seven of those who did not make 1-year follow-up had lost more than 15 letters when last seen, giving a responder rate of 54-20/54=63%.

CONCLUSION

There may not be as many patients eligible for PDT, using the TAP criteria, as previously hoped. The outcome of treatment appears similar to that found in the TAP study.

Verteporfin : a review of its use in the management of subfoveal choroidal neovascularisation

Verteporfin (Visudyne) therapy (photodynamic therapy with intravenous liposomal verteporfin) is the first treatment to effectively prevent the loss of visual acuity in patients with subfoveal choroidal neovascularisation (CNV) secondary to age-related macular degeneration (AMD), pathological myopia or presumed ocular histoplasmosis syndrome (POHS). In adult patients with classic subfoveal CNV or occult with no classic subfoveal CNV secondary to AMD, or subfoveal CNV secondary to pathological myopia or POHS, verteporfin therapy slows or prevents loss of visual acuity. In well designed clinical trials, verteporfin therapy was superior to placebo in patients with subfoveal classic-containing CNV and occult with no classic CNV secondary to AMD at 12 and/or 24 months (Treatment of Age-related macular degeneration with Photodynamic therapy [TAP] Investigation and Verteporfin In Photodynamic therapy [VIP-AMD] trial) and in patients with pathological myopia at 12 months (Verteporfin In Photodynamic therapy [VIP-PM] trial). Limited data suggest that verteporfin therapy also prevents loss of visual acuity in patients with subfoveal CNV secondary to POHS. Verteporfin therapy was generally well tolerated in clinical trials; most adverse events were mild to moderate in intensity and transient. The most frequently reported verteporfin therapy-related adverse events (incidence >2%) were visual disturbance, injection-site reactions, photosensitivity reactions and infusion-related back pain. Approximately 5% of patients with occult with no classic subfoveal CNV secondary to AMD reported severe vision decrease within 7 days of treatment in clinical trials; 3 months later, several patients had recovered some of this loss.

CONCLUSION

Photodynamic therapy with verteporfin, the first photosensitiser approved for the treatment of subfoveal CNV, is a well tolerated treatment that stabilises or slows visual acuity loss in adult patients with predominantly classic or occult with no classic subfoveal CNV secondary to AMD, and subfoveal CNV secondary to pathological myopia or POHS. Thus, verteporfin therapy provides a valuable option for the management of these patients for whom treatment options are few, and should be considered as a first-line therapy in these difficult-to-manage conditions.

Review Article. New treatments in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of legal blindness in individuals 50 years and older in the developed world. Choroidal neovascularization (CNV) in exudative AMD is responsible for the majority of severe vision loss. Until recently, laser photocoagulation was the only well-established and widely accepted treatment for CNV. However, it is beneficial only for a small subset of patients, has a high rate of CNV persistence and recurrence and results in iatrogenic, collateral damage to the overlying retina. These issues make it difficult to recommend in the case of subfoveal lesions. Consequently, numerous experimental therapeutic interventions are under investigation with the common objective of destroying the CNV but leaving the foveal neurosensory retina intact. Treatment modalities can be grouped into five major categories: photodynamic therapy; radiotherapy; transpupillary thermotherapy; anti-angiogenic and angiostatic agents; and surgical intervention. The present review aims to explain the rationale behind these new treatments, analyse the evidence for their safety and efficacy, determine their stage of development and indicate in which patients they are potentially useful.

Update on photodynamic therapy

To date, photodynamic therapy with verteporfin has been shown to benefit those patients with age-related molecular degeneration and choroidal neovascularization that is subfoveal and predominately classic (> 50%). As of this writing, the Food and Drug Administration is requiring additional data before verteporfin is approved for treatment of occult subfoveal choroidal neovascularization. Photodynamic therapy has also proved beneficial for subfoveal lesions secondary to high myopia. Although there is potential for patients with angioid streaks, ocular histoplasmosis syndrome, and idiopathic causes of choroidal neovascularization to benefit from photodynamic therapy, randomized clinical trials have not been performed. Photodynamic therapy has not been shown to benefit patients with minimally classic (< 50%) lesions.

Enhanced photodynamic activity of meso-tetra(4-hydroxyphenyl)porphyrin by incorporation into sub-200 nm nanoparticles

A photosensitizer, meso-tetra(hydroxyphenyl)porphyrin (p-THPP) was incorporated into sterile submicronic nanoparticles of poly(D,L-lactide-co-glycolide) (50:50 and 75:25 PLGA) and poly(D,L-lactide) (PLA). With all polymers used, sub-130 nm p-THPP-loaded nanoparticles with similar drug loadings and entrapment efficiencies were produced using the emulsification-diffusion technique. The photodynamic activity (photocytotoxicity) of these nanoparticles was evaluated on EMT-6 mammary tumour cells in comparison with the free drug. The influence of drug concentration (3-10 microg/ml), incubation time (5-60 min) and light dose (6-9 J/cm(2)) on p-THPP photocytotoxic efficiency was investigated. With all p-THPP formulations tested, cell viability decreased with increasing values of these parameters. The beneficial effect of nanoencapsulation compared to free drug was highlighted at drug concentrations up to 6 microg/ml and short incubation times (15-30 min). The most important photocytotoxicity was observed with 50:50 PLGA nanoparticles allowing low drug doses and short drug administration-irradiation intervals for local photodynamic therapy.

Sub-retinal neovascular membrane in exudative macular degeneration

Age-related macular degeneration is a major cause of serious vision loss. The earliest stages of age-related maculopathy may be defined by the size of the drusen present in the macula and the effects on vision. Further manifestations may include soft drusen, choroidal neovascularisation, macular haemorrhage and cicatricial or disciform degeneration of the macula. This report describes a patient with a macular haemorrhage, a choroidal neovascular membrane and serious loss of vision. In addition, the pathogenesis, diagnosis and treatment options of macular degeneration are reviewed.

Photodynamic therapy with verteporfin for choroidal neovascularization in patients with angioid streaks

PURPOSE

To evaluate safety and efficacy of photodynamic therapy with verteporfin for subfoveal choroidal neovascularization associated with angioid streaks.

DESIGN

Prospective interventional case series.

METHODS

Eight patients (eight eyes) with subfoveal choroidal neovascularization secondary to angioid streaks were reviewed. Standardized protocol refraction, visual acuity testing, ophthalmologic examinations, color photographs, fluorescein angiograms and indocyanine angiograms were used to evaluate the results of photodynamic therapy with verteporfin. Follow up ranged from 6 to 12 months with a mean (+/- SD) of 8.75 (+/- 2.37) months.

RESULTS

Photodynamic therapy with verteporfin was well tolerated in patients with choroidal neovascularization related to angioid streaks. No deterioration in visual acuity was observed. Increase in median best-corrected visual acuity was 1.37 lines (SD +/- 1.59 lines, range 1-5 lines) at the last follow up. Two (25%) patients had no improvement of visual acuity. At the last follow up three (37.5%) patients showed no leakage and three (37.5%) patients had minimal leakage from choroidal neovascularization. Photodynamic therapy related ocular complications were not reported in any case.

CONCLUSIONS

Photodynamic therapy with verteporfin generally achieved short-term cessation of or decrease of fluorescein leakage from subfoveal choroidal neovascularization without loss of vision in patients with angioid streaks. Further studies with longer follow up are necessary to confirm whether verteporfin therapy is beneficial for subfoveal choroidal neovascularization related to angioid streaks.

State of the art in the delivery of photosensitizers for photodynamic therapy

In photodynamic therapy, one of the problems limiting the use of many photosensitizers (PS) is the difficulty in preparing pharmaceutical formulations that enable their parenteral administration. Due to their low water solubility, the hydrophobic PS cannot be simply injected intravenously. Different strategies, including polymer-PS conjugation or encapsulation of the drug in colloidal carriers such as oil-dispersions, liposomes and polymeric particles, have been investigated. Although these colloidal carriers tend to accumulate selectively in tumour tissues, they are rapidly taken up by the mononuclear phagocytic system. In order to reduce this undesirable uptake by phagocytic cells, long-circulating carriers that consist of surface modified carriers have been developed. Moreover, considerable effort has been directed towards using other types of carriers to improve tumour targeting and to minimize the side effects. One of the approaches is to entrap PS into the lipophilic core of low-density lipoproteins (LDL) without altering their biological properties. The LDL receptor pathway is an important factor in the selective accumulation of PS in tumour tissue owing to the increased number of LDL receptors on the proliferating cell surface. Specific targeting can also be achieved by binding of monoclonal antibodies or specific tumour-seeking molecules to PS or by the coating of PS loaded carriers.