Photodynamic Therapy of Exudative Age-Related Macular Degeneration

Optimizing the functionality of clients with age-related macular degeneration

Age-related macular degeneration (ARMD) is a major cause of severe vision loss and blindness among older people. This condition is progressive, incurable, and significantly compromises central vision. Rehabilitation nurses have a pivotal role in the assessment and management of clients with ARMD. An understanding of incidence and pathophysiology of ARMD, as well as health promotion and a new treatment for ARMD can help rehabilitation nurses design interventions to help clients maintain an acceptable quality of life despite declining vision.

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.

Current concepts and recent advances in the management of age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of visual impairment and blindness in the Western World in those aged 65 and older. At present, several treatment modalities are utilised and several more are undergoing investigation in an attempt to retard the occurrence and progression of this devastating condition.

AIMS

To provide the non-ophthalmologist with an understanding of the current treatment options available to patients suffering from all variants of AMD.

METHODS

Medline and Embase search.

RESULTS

Several treatment modalities have been investigated and utilised in the treatment of all variants of this condition. While promising results have been reported, no treatment is ideal.

CONCLUSION

While no curative treatment for this condition currently exists, early recognition and treatment, if indicated, have been shown to reduce the risk of severe vision loss in patients with this condition.

The burden of age-related macular degeneration: results of a cohort study in two French referral centres

OBJECTIVE

To describe the economic impact of age-related macular degeneration (AMD) and to assess its medical and non-medical costs.

DESIGN AND SETTINGS

An observational study was carried out in 105 patients in two French centres in a sample of 105 French patients. All consecutive patients, consulting during a 3-week period, were included provided they were 60 years of age or older and they presented an exudative form of AMD with a distant visual acuity in the best eye < or = 20/40. Data collected included clinical items, treatment modalities, medical follow-up, transport costs, impact of AMD on living conditions and welfare payments related to visual impairment. Costs were presented in 2000 values.

PERSPECTIVE

General payer perspective (Social Security, private health insurance and patient).

RESULTS

Mean age was 79.3 years and ranged from 62.8-95 years. Average length of disease evolution was 3.5 years. During a 3-month period, patients had a mean of 2.6 visits to the ophthalmologist. Thirty percent of the patients used vascular medications and 72.4% had been previously treated by laser photocoagulation. Only 10% had benefited from visual rehabilitation. Annual AMD cost per patient was 3660.29 euros (EUR) [95% CI: 2881.92-4438.62]. Half of these annual costs were medical costs. Other major cost components were home help costs EUR904.91 [95% CI: 478.88-1330.94] and transport costs for care EUR542.73 [95% CI: 146.31-939.14]. Non-medical costs were significantly higher for patients with more severe disease.

CONCLUSIONS

The economic argument that costs are higher in patients with the lowest visual acuity emphasises the necessity of early detection and treatment of patients with AMD.

Photodynamic therapy for choroidal neovascularization: a review

PURPOSE

To review the biophysical basis and current state of therapy for photodynamic closure of subfoveal choroidal neovascularization in the eye.

METHODS

A review of the literature is included, which encompasses the chemical structure, biophysical mechanism of action, range of available agents, status of clinical trials, clinical indications, results of treatments, complications, and future directions.

RESULTS

Photodynamic therapy has been shown to be effective in closing both experimental choroidal neovascularization in animal models as well as subfoveal choroidal neovascularization in humans. The therapy results in temporary closure of choroidal new vessels for a period of approximately 1 to 4 weeks. By 12 weeks, most patients have reperfusion or reproliferation of choroidal new vessels resulting in the need for retreatment to achieve continued closure and visual stabilization. Differences exist in the quantum yield, clinical efficiency, and light and sensitizer dose requirements between different classes of agents. Further clinical trials will be required to determine the optimal form of therapy, with verteporfin (Visudyne) as the only currently approved agent. Other agents, including tin etiopurpurin (Purlytin) and motexafin lutetium (Optrin), are currently undergoing phase III, and phase II trials, respectively.

CONCLUSIONS

Photodynamic therapy is a promising treatment modality shown to be effective in achieving closure and stabilization of vision loss compared with placebo control in eyes with subfoveal choroidal neovascularization.

Verteporfin

Verteporfin, a benzoporphyrin derivative monoacid ring A, is a photosensitising drug for photodynamic therapy (PDT) activated by low-intensity, nonheat-generating light of 689nm wavelength. Activation generates cytotoxic oxygen free radicals. The specificity and uptake of verteporfin for target cells with a high expression of low density lipoprotein (LDL) receptors, such as tumour and neovascular endothelial cells, is enhanced by the use of a liposomal formulation and its rapid uptake by plasma LDL. Verteporfin therapy (at light doses < 150 J/cm) selectively damages neovascular endothelial cells leading to thrombus formation and specific occlusion of choroidal neovascular vessels in subfoveal lesions in patients with age-related macular degeneration (AMD). Repeated applications of verteporfin therapy 6 mg/m2 improved or maintained visual acuity in the majority of patients with some classic subfoveal choroidal neovascularisation (CNV) secondary to AMD at 1 year's follow-up in 2 large multicentre, placebo-controlled, double-blind trials. Furthermore. in a subgroup of these patients with predominantly classic CNV secondary to AMD, there was a significantly more marked visual acuity (VA) benefit with 67.3% of verteporfin-treated eyes experiencing less than a 15-letter loss of VA versus 39.3% with placebo treatment. Multiple applications of verteporfin therapy were well tolerated in patients with subfoveal CNV secondary to AMD. The most common adverse events were visual disturbances, injection site reactions, photosensitivity reactions and infusion-related back pain.