Age-related macular degeneration. Can we stem this worldwide public health crisis?

[Reasons for delayed and discontinued therapy in age-related macular degeneration]

BACKGROUND

Critical prerequisites for successful therapy of neovascular age-related macular degeneration (nvAMD) are an early initiation and continuous monitoring; however, delays in starting therapy and non-medically indicated discontinuation of therapy are frequent, which limits therapy efficacy and, thus, visual outcomes.

OBJECTIVE

To identify the reasons for delay in therapy and non-medically indicated termination of therapy.

MATERIAL AND METHODS

Patients who had started a new therapy (starters) and those who independently terminated therapy (dropouts) were interviewed by telephone with a specific, standardized questionnaire. Results were summarized descriptively.

RESULTS

A total of 100 starters and 55 dropouts were interviewed. The mean therapy delay was 22 (±28 SD) days. This was mainly due to the time until the decision to see an ophthalmologist was made. Main reasons for dropping out were: transportation issues (27%), poor general health (25%) and the assumption that there is no benefit from therapy (11%). Of the patients who dropped out 63% would have liked to continue therapy.

CONCLUSION

There is potential for improvement in nvAMD management regarding therapy start as well as therapy maintenance. Sensitizing for initial nvAMD symptoms is important as is reduction of barriers to therapy maintenance, since most therapy dropouts would like to continue the therapy.

Ocular Risk Factors for Exudative AMD: A Novel Semiautomated Grading System

Purpose. To evaluate the contribution of the ocular risk factors in the conversion of the fellow eye of patients with unilateral exudative AMD, using a novel semiautomated grading system. Materials and Methods. Single-center, retrospective study including 89 consecutive patients with unilateral exudative AMD and ≥3 years of followup. Baseline color fundus photographs were graded using an innovative grading software, RetmarkerAMD (Critical Health SA). Results. The follow-up period was 60.9 ± 31.3 months. The occurrence of CNV was confirmed in 42 eyes (47.2%). The cumulative incidence of CNV was 23.6% at 2 years, 33.7% at 3 years, 39.3% at 5 years, and 47.2% at 10 years, with a mean annual incidence of 12.0% (95% CI = 0.088–0.162). The absolute number of drusen in the central 1000 and 3000 μm (P < 0.05) and the absolute number of drusen ≥125 µm in the central 3000 and 6000 µm (P < 0.05) proved to be significant risk factors for CNV. Conclusion. The use of quantitative variables in the determination of the OR of developing CNV allowed the establishment of significant risk factors for neovascularization. The long follow-up period and the innovative methodology reinforce the value of our results. This trial is registered with ClinicalTrials.gov NCT00801541.

Adeno-associated vector (type 8)-mediated expression of soluble Flt-1 efficiently inhibits neovascularization in a murine choroidal neovascularization model

To assess the feasibility of a gene therapeutic approach to treating choroidal neovascularization (CNV), we generated a recombinant adeno-associated viral (AAV) vector (type 8) encoding soluble Flt-1 (AAV-sflt-1), and determined its ability to inhibit angiogenesis. When we treated human umbilical vein endothelial cells (HUVECs) with the supernatant of cells transduced with AAV-sflt-1 or AAV-EGFP (control), we found that tube formation was significantly inhibited by the former but not the latter (area: 25,121 +/- 557 vs. 68,628 +/- 1357 pixels [p < 0.01]; length: 4811 +/- 246 vs. 10,894 +/- 297 pixels [p < 0.01]). CNV was induced in C57BL/6 mice by making four separate choroidal burns around the optic nerve in each eye, using a diode laser. Thereafter, 2 microl (5 x 10(11) vector genomes/ml) of AAV-sflt-1 (n = 11) or control AAV-LacZ (n = 12) was injected into the subretinal space, and 2 weeks later the eyes were removed for flatmount analysis of CNV surface area. Notably, subretinal delivery of AAV-sflt-1 significantly diminished CNV at the laser lesions, as compared with AAV-LacZ (555 +/- 304 vs. 1470 +/- 1000 microm(2); p = 0.007). These results suggest that there was diffusion of the secreted sFlt-1 across the retina and that long-term suppression of CNV is possible through the use of stable rAAV-mediated sflt-1 expression. In vivo gene therapy thus appears to be a feasible approach to the clinical management of CNV in conditions such as age-related macular degeneration.

Genetics and molecular pathology of Stargardt-like macular degeneration

Stargardt-like macular degeneration (STGD3) is an early onset, autosomal dominant macular degeneration. STGD3 is characterized by a progressive pathology, the loss of central vision, atrophy of the retinal pigment epithelium, and accumulation of lipofuscin, clinical features that are also characteristic of age-related macular degeneration. The onset of clinical symptoms in STGD3, however, is typically observed within the second or third decade of life (i.e., starting in the teenage years). The clinical profile at any given age among STGD3 patients can be variable suggesting that, although STGD3 is a single gene defect, other genetic or environmental factors may play a role in moderating the final disease phenotype. Genetic studies localized the STGD3 disease locus to a small region on the short arm of human chromosome 6, and application of a positional candidate gene approach identified protein truncating mutations in the elongation of very long chain fatty acids-4 gene (ELOVL4) in patients with this disease. The ELOVL4 gene encodes a protein homologous to the ELO group of proteins that participate in fatty acid elongation in yeast. Pathogenic mutations found in the ELOVL4 gene result in altered trafficking of the protein and behave with a dominant negative effect. Mice carrying an Elovl4 mutation developed photoreceptor degeneration and depletion of very long chain fatty acids (VLCFA). ELOVL4 protein participates in the synthesis of fatty acids with chain length longer than 26 carbons. Studies on ELOVL4 indicate that VLCFA may be necessary for normal function of the retina, and the defective protein trafficking and/or altered VLCFA elongation underlies the pathology associated with STGD3. Determining the role of VLCFA in the retina and discerning the implications of abnormal trafficking of mutant ELOVL4 and depleted VLCFA content in the pathology of STGD3 will provide valuable insight in understanding the retinal structure, function, and pathology underlying STGD3 and may lead to a better understanding of the process of macular disease in general.

The introduction of verteporfin photodynamic therapy in the UK: PDT users group (PDTUG) surveillance programme report 1

AIMS

To report overall patient recruitment characteristics and visual acuity (VA) outcome related to baseline lesion characteristics for patients with choroidal neovascularisation (CNV) treated with verteporfin photodynamic therapy (PDT) during its introduction into routine National Health Service practice.

METHODS

Thirteen treatment centres prospectively submitted data on patients undergoing verteporfin PDT for CNV of mixed aetiology between November 1999 and May 2004 into the PDT Users Group (PDTUG) surveillance database. The primary outcome was the proportion of eyes losing <15 letters of VA at 12 and 24 months, follow-up compared with the baseline examination.

RESULTS

One thousand eight hundred and ninety-four eyes of 1755 patients were analysed. Lesion characteristics at baseline were: classic no occult 1152 (67.4%), predominantly classic with occult 531 (31.1%). Recruitment rate rose steadily from 13 in the first to 188 in the final quarter. Data were available at 12 months on 1010 (53.3%) and at 24 months on 310 (16.4%) eyes. The proportion of eyes losing <15 letters was 71% (716/1010) at 12 months and 70% (217/310) at 24 months. At 12 months 91% (917/1010) of patients lost <30 letters. The mean number of PDT treatments for the cohort was 2.4 in the first 12 months. An adverse reaction or event was reported in 8.1% (364/4515) of treatments. Non-visual adverse events were infrequent.

CONCLUSIONS

Efficacy and safety of verteporfin PDT in reducing vision loss in macular degeneration can be reproduced in routine clinical practice. Compared to the TAP study, the fewer treatments needed in the PDTUG cohort indicate the potential for better cost-effectiveness.

Quantitative enumeration of vascular smooth muscle cells and endothelial cells derived from bone marrow precursors in experimental choroidal neovascularization

Choroidal neovascularization (CNV) is characterized by the subretinal invasion of a pathologic new vessel complex from the choriocapillaris. Although CNV is traditionally considered to consist of endothelial cells, the cellular population of CNV is likely more complex in nature, comprising several different cell types. In addition, recent studies suggest that the CNV cell population has a dual origin (circulating versus resident populations). In this study we sought to determine the contribution and origin of different cell types in experimental CNV. Laser-induced CNV was performed on chimeric mice generated by reconstituting C57BL/6 mice with bone marrow from green fluorescent protein (GFP)-transgenic mice. In these mice, bone marrow-derived cells are GFP-labeled. Immunofluorescence staining was used to examine both flatmount preparations of the choroid and cross sections of the posterior pole for macrophages, endothelial cells, vascular smooth muscle cells, retinal pigment epithelial (RPE) cells, lymphocytes, or neutrophils at day 3, 7, 14 and 28 post-laser (n=5 per group). Cell types present in CNV included macrophages (20% of the cells in CNV), endothelial cells (25%), vascular smooth muscle cells (11%), RPE cells (12%) and non-labeled cells (32%). The macrophage population was mostly derived from circulating monocytes at all timepoints studied (70% were GFP labeled), while endothelial and vascular smooth muscle cells were partly bone marrow derived (50-60% were GFP labeled), and RPE cells appeared to be entirely derived from preexisting tissue resident cells. These results demonstrate that bone marrow-derived progenitor cells contribute significantly to the vascular and inflammatory components of CNV. Knowledge of the cellular composition and origin might help understand the pathogenic mechanisms controlling CNV severity as well as indicate potential targets for therapeutic intervention.

Colour vision testing as an aid to diagnosis and management of age related maculopathy

AIM

To provide a simple test that detects the onset of age related maculopathy (ARM), and can be used to monitor its severity.

METHODS

Colour contrast sensitivity was measured using computer graphics techniques. Colour thresholds were measured along tritan and protan colour confusion axes in the presence of dynamic luminance noise. Thresholds were determined separately for two sizes of optotypes (6.5 degrees and 1.5 degrees). Natural pupils were used. Normal values for the test have been established.

RESULTS

In all patients with unilateral age related macular degeneration, the smaller optotype was invisible in that eye and in almost all, the larger optotype could not be seen. In the symptomless fellow eyes (with ARM) the larger optotype thresholds were raised. The degree of loss was larger for tritan. For the smaller optotype, protan thresholds were elevated in the majority of patients. Tritan losses were greater and disproportionate to the loss seen with the larger optotype. Every person including those with minimal fundal changes had tritan test results for 1.5 degree optotypes >2 SD above the normal mean. Tritan thresholds varied with the severity of the ARM.

CONCLUSIONS

The test is sensitive, simple and quick to administer, and easy for patients. Therefore, it should be useful in detecting and monitoring elderly people with age related changes in their fundi before irreversible loss of vision has occurred.

Perceived quality of health care in macular disease: a survey of members of the Macular Disease Society

AIM

To investigate the experiences of people with macular disease within the British healthcare system.

METHOD

The Macular Disease Society Questionnaire, a self completion questionnaire designed to survey the experiences of people with macular disease, was sent to 2000 randomly selected members of the Macular Disease Society. The questionnaire incorporated items about people's experiences with health professionals and the information and support provided by them at the time of diagnosis and thereafter.

RESULTS

Over 50% thought their consultant eye specialist was not interested in them as a person and 40% were dissatisfied with their diagnostic consultation. 185 people thought their general practitioner (GP) was well informed about macular disease but twice as many people thought their GP was not well informed. About an equal number of people thought their GP was supportive as those who thought their GP was not supportive. A total of 1247 people were told "nothing can be done to help with your macular disease." A number of negative emotional reactions were experienced by those people as a result, with 61% of them reporting feeling anxious or depressed. Of 282 people experiencing visual hallucinations after diagnosis with macular disease, only 20.9% were offered explanations for them.

CONCLUSIONS

Many people with macular disease have unsatisfactory experiences of the healthcare system. Many of the reasons for dissatisfaction could be resolved by healthcare professionals if they were better informed about macular disease and had a better understanding of and empathy with patients' experiences.

Dose response of rat retinal microvessels to proton dose schedules used clinically: a pilot study

PURPOSE

This preclinical rat pilot study quantifies retinal microvessel, endothelial, and pericyte population changes produced by proton irradiation

METHODS AND MATERIALS

The left eyes of rats were irradiated with single doses of 8, 14, 20, and 28 Gy protons; right eyes, with two fractions. Animals were euthanized, and eyes were removed; elastase digests were prepared, and cell populations were counted in sample fields. Results were compared with unirradiated controls.

RESULTS

Progressive time- and dose-dependent endothelial cell loss occurred following all schedules. Cell loss was significantly different from control values (p < 0.001) following 28 Gy and following 20 Gy (p < 0.05) in a single dose. Endothelial cell loss was the same for single- and split-dose schedules. Progressive endothelial cell loss produced vessel collapse and acellular vessel strands. Endothelial cells were in the G(0) phase of the mitotic cycle. 28 Gy produced photoreceptor cell loss.

CONCLUSION

The retinal digest is an elegant bioassay to quantify the microvessel population response. Single- and split-dose schedules appear to yield similar outcomes, in terms of endothelial cell density.

Age-related macular degeneration: a randomized clinical trial of a self-management intervention

The purpose of this study was to conduct a randomized clinical trial to assess whether a self-management group intervention can improve mood, self-efficacy, and activity in people with central vision loss due to age-related macular degeneration (AMD). Ninety-two elderly patients with AMD (average age = 79) from a university ophthalmology clinic were randomly assigned to the self-management intervention (n = 44) or to a wait-list (n = 48). All patients were legally blind in at least one eye. The intervention consisted of 6 weekly 2-hour group sessions providing education about the disease, group discussion, and behavioral and cognitive skills training to address barriers to independence. All participants eventually completed the intervention allowing pre-post comparisons for all patients. The battery of measures included the Profile of Mood States (POMS); Quality of Well-Being Scale; and assessments of self-efficacy, participation in activities, and use of vision aids. Participants' initial psychological distress was high (mean total POMS = 59.72) and similar to distress experienced by other serious chronic illness populations (e.g. cancer, bone marrow transplant). Analysis of covariance testing the primary hypothesis revealed that intervention participants experienced significantly (p = .04) reduced psychological distress (pre mean = 61.45; post mean = 51.14) in comparison with wait-list controls (pre mean = 57.72; post mean = 62.32). Intervention participants also experienced improved (p = .02) self-efficacy (pre mean = 70.16; post mean = 77.27) in comparison with controls (pre mean = 67.71; post mean = 69.07). Further, intervention participants increased their use of vision aids (p < .001; pre mean = 3.37, post mean = 6.69). This study demonstrates that a relatively brief behavioral intervention can substantially reduce psychological distress and increase self-efficacy in elderly adults experiencing vision loss due to macular degeneration. Self-management intervention appears to improve mood, self-efficacy, and use of vision aids, further enhancing the lives of poorly sighted individuals with AMD.