Associations with baseline visual acuity in 12,414 eyes starting treatment for neovascular AMD

AIMS

To determine baseline visual acuity before the start of treatment for neovascular age-related macular degeneration (AMD), compare median and visual acuity states between treatment sites and investigate the association of socio-demographic and clinical characteristics with baseline acuity.

METHODS

Anonymised demographic and clinical data, collected as part of routine clinical care, were extracted from electronic medical records at treating National Health Service (NHS) Trusts. Analyses were restricted to eyes with baseline visual acuity recorded at treatment initiation. Associations with baseline acuity were investigated using multivariate linear regression.

RESULTS

Analysis included 12,414 eyes of 9116 patients at 13 NHS Trusts. Median baseline acuity was LogMAR 0.46 (interquartile range = 0.26-0.80) and 34.5% of eyes had good acuity, defined as LogMAR ≤0.3. Baseline acuity was positively associated with second-treated eye status, younger age, lower socio-economic deprivation, independent living, and female sex. There was little evidence of association between baseline acuity and distance to the nearest treatment centre, systemic or ocular co-morbidity. Despite case-mix adjustments, there was evidence of significant variation of baseline visual acuity between sites.

CONCLUSIONS

Despite access to publicly funded treatment within the NHS, variation in visual acuity at the start of neovascular AMD treatment persists. Identifying the characteristics associated with poor baseline acuity, targeted health awareness campaigns, professional education, and pathway re-design may help to improve baseline acuity, the first eye gap, and visual acuity outcomes.

The rare C9 P167S risk variant for age-related macular degeneration increases polymerization of the terminal component of the complement cascade

Age-related macular degeneration (AMD) is a complex neurodegenerative eye disease with behavioral and genetic etiology and is the leading cause of irreversible vision loss among elderly Caucasians. Functionally significant genetic variants in the alternative pathway of complement have been strongly linked to disease. More recently, a rare variant in the terminal pathway of complement has been associated with increased risk, Complement component 9 (C9) P167S. To assess the functional consequence of this variant, C9 levels were measured in two independent cohorts of AMD patients. In both cohorts, it was demonstrated that the P167S variant was associated with low C9 plasma levels. Further analysis showed that patients with advanced AMD had elevated sC5b-9 compared to those with non-advanced AMD, although this was not associated with the P167S polymorphism. Electron microscopy of membrane attack complexes (MACs) generated using recombinantly produced wild type or P167S C9 demonstrated identical MAC ring structures. In functional assays, the P167S variant displayed a higher propensity to polymerize and a small increase in its ability to induce hemolysis of sheep erythrocytes when added to C9-depleted serum. The demonstration that this C9 P167S AMD risk polymorphism displays increased polymerization and functional activity provides a rationale for the gene therapy trials of sCD59 to inhibit the terminal pathway of complement in AMD that are underway.

Epigenetics in age-related macular degeneration: new discoveries and future perspectives

The study of epigenetics has explained some of the ‘missing heritability’ of age-related macular degeneration (AMD). The epigenome also provides a substantial contribution to the organisation of the functional retina. There is emerging evidence of specific epigenetic mechanisms associated with AMD. This ‘AMD epigenome’ may offer the chance to develop novel AMD treatments.

A systematic review to assess the 'treat-and-extend' dosing regimen for neovascular age-related macular degeneration using ranibizumab

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the developed world. Monthly or as-needed (PRN) dosing strategies of intravitreal ranibizumab have been established as efficacious treatment options for neovascular AMD. More recently, the 'treat-and-extend' dosing regimen (TREX) is being adopted in clinical practice as it represents a patient-centric and economical option, reducing treatment burden by extending injection intervals when possible. However, the efficacy of TREX using ranibizumab monotherapy remains to be defined. Therefore, we performed a systematic review to assess the current evidence for TREX using ranibizumab by searching MEDLINE, Embase and PubMed. Of the 1733 articles identified, nine TREX studies were included in our analysis (n=748 eyes). Average patient age was 79.25 (range: 77.34-82.00; SD: 7.27). Baseline BCVA ranged from 48.5-68.9 ETDRS letters. BCVA improvement was 8.92 letters at 1 year (range: 6.5-11.5; SD: 7.54), as a weighted mean accounting for numbers of study eyes. The weighted mean number of injections at one year was 8.60 (range: 7.3-12.0; SD: 1.73). Previously, the landmark ANCHOR and MARINA trials reported gains of 11.3 and 7.2 letters, respectively, using monthly ranibizumab. Chin-Yee et al reported a gain of 3.5 ETDRS letters with 5.3 (S.D. 0.66) PRN ranibizumab injections as weighted means at 1 year in their recent systematic review. Our analysis suggests that TREX delivers visual outcomes superior to PRN and approaches similar efficacy to monthly injections. Further RCTs are needed to fully evaluate the efficacy and economy of TREX in the long-term.

One-year real-world outcomes in patients receiving fixed-dosing aflibercept for neovascular age-related macular degeneration

PurposeTo investigate 1-year visual and anatomic outcomes of intravitreal aflibercept for neovascular age-related macular degeneration (nAMD) given at a fixed 8-weekly interval.MethodsRetrospective, single-practice data analysis from an electronic medical record system of 255 eyes (223 patients) with treatment-naïve nAMD receiving 8-weekly aflibercept.ResultsMean logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) improved from 0.66 at baseline to 0.50 at month 11 (P<0.0001). Mean central retinal thickness (CRT) decreased from 311 μm at baseline to 211 μm at month 11 (P<0.0001). Our mean VA gain of eight ETDRS letters was comparable to the VIEW 1 and VIEW 2 Trials' results at the end of year 1. After loading at month 5, mean BCVA was 0.48 (P<0.0001), and mean CRT was 235 μm. At month 5, 143 eyes (56%) were inactive defined by the absence of macular haemorrhage and intraretinal fluid (IRF) and subretinal fluid (SRF) on optical coherence tomography, and 112 eyes (44%) remained active. At month 11, 136 eyes (53%) were inactive, and 119 eyes (47%) remained active. At month 11, 77% of inactive eyes after loading remained inactive, and 77% of the active eyes after loading remained active. At month 11, mean BCVA of the inactive group was 0.51, and mean BCVA of the active group was 0.48 (P=0.54).ConclusionsAflibercept administered by fixed dosing over 1 year improved VA and macular morphology in treatment-naïve eyes. Active lesions at month 11 do not have worse VA outcomes compared with inactive lesions. The macular status after loading is a reliable indicator of disease activity at the end of year 1.

Risk of geographic atrophy in age-related macular degeneration patients treated with intravitreal anti-VEGF agents

Anti-vascular endothelial growth factor (VEGF) intravitreal agents are the only successful treatment for wet age-related macular degeneration (AMD). However, there are emerging signals that anti-VEGF treatment can potentially increase development of geographic atrophy (GA). Histopathologic, animal, and clinical studies support this hypothesis although direct proof of a relationship between GA and use of anti-VEGF agents in neovascular AMD is not yet established. This review presents current evidence supporting an association between anti-VEGF therapy and progression of geographic atrophy. The need of exploring alternative methods of treating AMD is indirectly but clearly emphasized.

Multicolor imaging in the diagnosis and follow up of type 2 acute macular neuroretinopathy

PurposeTo study the usefulness of multicolor imaging (MC) photographs in addition to near infrared reflectance (NIR) and spectral domain optical coherence tomography (SD-OCT) in the detection and follow up of acute macular neuroretinopathy (AMN).Patients and methodsSix patients with a complaint of paracentral scotomas in at least one eye due to AMN were included. They underwent full ophthalmic examination and multimodal imaging including color fundus photographs, (SD-OCT), NIR, and MC at baseline and follow up.ResultsFour females and two males, aged 19-64 years, and eight eyes affected by AMN, were included. Acute phase SD-OCT in all patients confirmed the diagnosis of type 2 AMN with partial recovery of the outer retina in the convalescent phase. NIR and MC elicited in all cases hypo-reflective AMN lesions pointing toward the fovea. MC exhibited a higher contrast between the affected and the physiologic retina that slowly attenuated during the follow up showing a decrease in the hypo-reflectance of the lesions.ConclusionMC imaging was more detailed than fundus color photographs and as detailed as NIR in the detection of AMN. When available, MC imaging should complement SD-OCT and NIR in the diagnosis and follow up of this rare inflammatory condition that may be underdiagnosed.

Retinal pigment epithelium transplantation: concepts, challenges, and future prospects

The retinal pigment epithelium (RPE) is a single layer of cells that supports the light-sensitive photoreceptor cells that are essential for retinal function. Age-related macular degeneration (AMD) is a leading cause of visual impairment, and the primary pathogenic mechanism is thought to arise in the RPE layer. RPE cell structure and function are well understood, the cells are readily sustainable in laboratory culture and, unlike other cell types within the retina, RPE cells do not require synaptic connections to perform their role. These factors, together with the relative ease of outer retinal imaging, make RPE cells an attractive target for cell transplantation compared with other cell types in the retina or central nervous system. Seminal experiments in rats with an inherited RPE dystrophy have demonstrated that RPE transplantation can prevent photoreceptor loss and maintain visual function. This review provides an update on the progress made so far on RPE transplantation in human eyes, outlines potential sources of donor cells, and describes the technical and surgical challenges faced by the transplanting surgeon. Recent advances in the understanding of pluripotent stem cells, combined with novel surgical instrumentation, hold considerable promise, and support the concept of RPE transplantation as a regenerative strategy in AMD.

Dementia of the eye: the role of amyloid beta in retinal degeneration

Age-related macular degeneration (AMD) is one of the most common causes of irreversible blindness affecting nearly 50 million individuals globally. The disease is characterised by progressive loss of central vision, which has significant implications for quality of life concerns in an increasingly ageing population. AMD pathology manifests in the macula, a specialised region of the retina, which is responsible for central vision and perception of fine details. The underlying pathology of this complex degenerative disease is incompletely understood but includes both genetic as well as epigenetic risk factors. The recent discovery that amyloid beta (Aβ), a highly toxic and aggregate-prone family of peptides, is elevated in the ageing retina and is associated with AMD has opened up new perspectives on the aetiology of this debilitating blinding disease. Multiple studies now link Aβ with key stages of AMD progression, which is both exciting and potentially insightful, as this identifies a well-established toxic agent that aggressively targets cells in degenerative brains. Here, we review the most recent findings supporting the hypothesis that Aβ may be a key factor in AMD pathology. We describe how multiple Aβ reservoirs, now reported in the ageing eye, may target the cellular physiology of the retina as well as associated layers, and propose a mechanistic pathway of Aβ-mediated degenerative change leading to AMD.

Optical coherence tomography for the diagnosis of neovascular age-related macular degeneration: a systematic review

The purpose is to study the diagnostic performance of optical coherence tomography (OCT) and alternative diagnostic tests for neovascular age-related macular degeneration (nAMD). Methods employed are as follows:systematic review and meta-analysis;

INDEX TEST

OCT including time-domain (TD-OCT) and the most recently developed spectral domain (SD-OCT); comparator tests: visual acuity, clinical evaluation (slit lamp), Amsler chart, colour fundus photographs, infra-red reflectance, red-free images/blue reflectance, fundus autofluorescence imaging (FAF), indocyanine green angiography (ICGA), preferential hyperacuity perimetry (PHP), and microperimetry; reference standard: fundus fluorescein angiography. Databases searched included MEDLINE, MEDLINE In Process, EMBASE, Biosis, SCI, the Cochrane Library, DARE, MEDION, and HTA database. Last literature searches: March 2013. Risk of bias assessed using QUADAS-2. Meta-analysis models were fitted using hierarchical summary receiver operating characteristic (HSROC) curves. Twenty-two studies (2 abstracts and 20 articles) enrolling 2124 participants were identified, reporting TD-OCT (12 studies), SD-OCT (1 study), ICGA (8 studies), PHP (3 studies), Amsler grid, colour fundus photography and FAF (1 study each). Most studies were considered to have a high risk of bias in the patient selection (55%, 11/20), and flow and timing (40%, 8/20) domains. In a meta-analysis of TD-OCT studies, sensitivity and specificity (95% CI) were 88% (46-98%) and 78% (64-88%), respectively. There was insufficient information to undertake meta-analysis for other tests. TD-OCT is a sensitive test for detecting nAMD, although specificity was only moderate. Data on SD-OCT are sparse. Diagnosis of nAMD should not rely solely on OCT.

The role of epigenetics in age-related macular degeneration

It is becoming increasingly evident that epigenetic mechanisms influence gene expression and can explain how interactions between genetics and the environment result in particular phenotypes during development. The extent to which this epigenetic effect contributes to phenotype heritability in age-related macular degeneration (AMD) is currently ill defined. However, emerging evidence suggests that epigenetic changes are relevant to AMD and as such provide an exciting new avenue of research for AMD. This review addresses information on the impact of posttranslational modification of the genome on the pathogenesis of AMD, such as DNA methylation changes affecting antioxidant gene expression, hypoxia-regulated alterations in chromatin structure, and histone acetylation status in relation to angiogenesis and inflammation. It also contains information on the role of non-coding RNA-mediated gene regulation in AMD at a posttranscriptional (before translation) level. Our aim was to review the epigenetic mechanisms that cause heritable changes in gene activity without changing the DNA sequence. We also describe some long-term alterations in the transcriptional potential of a cell, which are not necessarily heritable but remains to be defined in the future. Increasing understanding of the significance of common and rare genetic variants and their relationship to epigenetics and environmental influences may help in establishing methods to assess the risk of AMD. This in turn may allow new therapeutic interventions for the leading cause of central vision impairment in patients over the age of 50 years in developed countries. Search strategy We searched the MEDLINE/PubMed database following MeSH suggestions for articles including the terms: 'ocular epigenetic mechanisms', 'human disease epigenetics', and 'age-related macular degeneration genetics'. The headline used to locate related articles in PubMed was 'epigenetics in ocular disease', and to restrict search, we used the headlines 'DNA methylation in age related macular degeneration', 'altered gene expression in AMD pathogenesis'. A manual search was also based on references from these articles as well as review articles.

Phenotype/genotype correlation in a case series of Stargardt's patients identifies novel mutations in the ABCA4 gene

PURPOSE

To investigate phenotypic variability in terms of best-corrected visual acuity (BCVA) in patients with Stargardt disease (STGD) and confirmed ABCA4 mutations.

METHODS

Entire coding region analysis of the ABCA4 gene by direct sequencing of seven patients with clinical findings of STGD seen in the Retina Clinics of Southampton Eye Unit between 2002 and 2011.Phenotypic variables recorded were BCVA, fluorescein angiographic appearance, electrophysiology, and visual fields.

RESULTS

All patients had heterozygous amino acid-changing variants (missense mutations) in the ABCA4 gene. A splice sequence change was found in a 30-year-old patient with severly affected vision. Two novel sequence changes were identified: a missense mutation in a mildly affected 44-year-old patient and a frameshift mutation in a severly affected 34-year-old patient.

CONCLUSION

The identified ABCA4 mutations were compatible with the resulting phenotypes in terms of BCVA. Higher BCVAs were recorded in patients with missense mutations. Sequence changes, predicted to have more deleterious effect on protein function, resulted in a more severe phenotype. This case series of STGD patients demonstrates novel genotype/phenotype correlations, which may be useful to counselling of patients. This information may prove useful in selection of candidates for clinical trials in ABCA4 disease.

Ranibizumab for the treatment of choroidal neovascularisation secondary to pathological myopia: interim analysis of the REPAIR study

AIMS

To evaluate the efficacy and safety of intravitreal ranibizumab in patients with choroidal neovascularisation secondary to pathological myopia (myopic CNV). Data are from a pre-planned, 6-month interim analysis.

METHODS

Phase II, open-label, single arm, multicentre, 12-month study, recruiting patients (aged ≥18 years) with active primary or recurrent subfoveal or juxtafoveal myopic CNV, with a best-corrected visual acuity (BCVA) score of 24-78 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in the study eye and a diagnosis of high myopia of at least -6 dioptres. Patients received 0.5 mg ranibizumab administered intravitreally to the study eye, followed by monthly injections given as needed (based on a predefined algorithm) for up to 11 months.

RESULTS

At 6 months, mean BCVA improved from baseline by 12.2 letters, as did central macular thickness (in this interim analysis defined as a measure of either central subfield macular thickness or centre point macular thickness) from baseline by 108 μm in the 48 study eyes of 48 patients. Fewer patients had centre-involving intraretinal oedema (13.0% vs 91.5%), intraretinal cysts (10.9% vs 57.4%), or subretinal fluid (13.0% vs 66.0%) at 6 months than at baseline. Patients received a mean of 1.9 retreatments, were satisfied with ranibizumab treatment, and well being was maintained. No new safety signals were identified.

CONCLUSIONS

Results from the planned interim analysis support the role of ranibizumab in the treatment of myopic CNV, with excellent efficacy achieved with a low number of injections and few serious adverse events.

Ranibizumab for the treatment of choroidal neovascularisation secondary to pathological myopia: interim analysis of the REPAIR study

AIMS

To evaluate the efficacy and safety of intravitreal ranibizumab in patients with choroidal neovascularisation secondary to pathological myopia (myopic CNV). Data are from a pre-planned, 6-month interim analysis.

METHODS

Phase II, open-label, single arm, multicentre, 12-month study, recruiting patients (aged ≥18 years) with active primary or recurrent subfoveal or juxtafoveal myopic CNV, with a best-corrected visual acuity (BCVA) score of 24-78 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in the study eye and a diagnosis of high myopia of at least -6 dioptres. Patients received 0.5 mg ranibizumab administered intravitreally to the study eye, followed by monthly injections given as needed (based on a predefined algorithm) for up to 11 months.

RESULTS

At 6 months, mean BCVA improved from baseline by 12.2 letters, as did central macular thickness (in this interim analysis defined as a measure of either central subfield macular thickness or centre point macular thickness) from baseline by 108 μm in the 48 study eyes of 48 patients. Fewer patients had centre-involving intraretinal oedema (13.0% vs 91.5%), intraretinal cysts (10.9% vs 57.4%), or subretinal fluid (13.0% vs 66.0%) at 6 months than at baseline. Patients received a mean of 1.9 retreatments, were satisfied with ranibizumab treatment, and well being was maintained. No new safety signals were identified.

CONCLUSIONS

Results from the planned interim analysis support the role of ranibizumab in the treatment of myopic CNV, with excellent efficacy achieved with a low number of injections and few serious adverse events.

Retinal angiomatous proliferation occurring after radiotherapy

PURPOSE

To describe two cases of retinal angiomatous proliferation (RAP)-like lesion following radiation therapy for primary tumor.

PATIENTS AND METHODS

Retrospective evaluation of two patients with previous irradiation treatment for a pleomorphic adenoma of the lacrimal gland and a vocal cord carcinoma, respectively. Visual acuity (VA), fluorescein angiography and optical coherence tomography were performed and demonstrated a RAP-like lesion in both cases. Treatment with intravitreal injections of Ranibizumab was performed with a follow-up of 19 and 10 months, respectively.

RESULTS

Both the patients had a positive response to the treatment with improvement in VA and reduction of intraretinal fluid.

CONCLUSION

RAP-like lesions can develop following radiation treatment for a primary tumor. In patients presenting with idiopathic RAP, a history of prior radiotherapy should be considered.

Photodynamic therapy for retinal capillary hemangioma

PURPOSE

To describe the results of photodynamic therapy (PDT) for juxtapapillary and peripheral retinal capillary hemangioma (RCH).

PATIENTS AND METHODS

Interventional case series of four eyes (four patients) with juxtapapillary RCH and one eye (one patient) with peripheral RCH. Two eyes with juxtapapillary RCH had received two sessions of full-fluence, double-duration PDT; whereas other two eyes had received single session of half-fluence, single-duration PDT. The peripheral RCH was treated with a single session of full-fluence, single-duration PDT.

RESULTS

Two patients had von Hippel-Lindau disease. Follow-up duration ranged from 4 months to 1 year. Pre-PDT visual acuity (VA) ranged from 20/200 to HM (juxtapapillary RCH) and 20/100 (peripheral RCH). Among the eyes with juxtapapillary RCH, tumor regression with partial resolution of macular edema was noted in two eyes (one eye each with half-fluence and full-fluence PDT), whereas two eyes had no change in tumor size with persistent macular edema. VA remained stable in three eyes and declined in one eye. In an eye with peripheral RCH, regression of tumor and macular edema with VA improvement was noted. Post-PDT complications included epiretinal membrane (one eye) and transient exudative retinal detachment (one eye).

CONCLUSION

PDT can be effective in reducing macular edema associated with RCH but this does not always correspond with an improvement in VA especially for juxtapapillary tumors.

Can genetic risk information for age-related macular degeneration influence motivation to stop smoking? A pilot study

AIMS

Smoking can increase the risk of macular degeneration and this is more than additive if a person also has a genetic risk. The purpose of this study was to examine whether knowledge of genetic risk for age-related macular degeneration (AMD) could influence motivation to quit smoking.

METHODS

A questionnaire-based study of hypothetical case scenarios given to 49 smokers without AMD. Participants were randomly allocated to a generic risk, high genetic risk, or low genetic risk of developing AMD scenario.

RESULTS

Forty-seven percent knew of the link between smoking and eye disease. In all, 76%, 67%, and 46% for the high risk, generic, and low risk groups, respectively, would rethink quitting (P for trend = 0.082). In all, 67%, 40%, and 38.5%, respectively, would be likely, very likely, or would definitely quit in the following month (P for trend = 0.023). Few participants (<16% of any group) were very likely to or would definitely attend a quit smoking session with no difference across groups. In all, 75.5% of participants would consider taking a genetic test for AMD.

CONCLUSION

In this pilot study, a trend was seen for the group given high genetic risk information to be more likely to quit than the generic or low genetic risk groups. Participants were willing to take a genetic test but further work is needed to address the cost benefits of routine genetic testing for risk of AMD. More generic risk information should be given to the public, and health warnings on cigarette packets that 'smoking causes blindness' is a good way to achieve this.

A study of a family with the skeletal muscle RYR1 mutation (c.7354C>T) associated with central core myopathy and malignant hyperthermia susceptibility

Congenital myopathies are early onset hereditary muscle disorders. A sub-group of these is associated with malignant hyperthermia susceptibility. Mutations in the skeletal muscle ryanodine receptor (RYR1) gene have been associated with various congenital myopathy phenotypes and may also cause malignant hyperthermia susceptibility. We describe nine affected members of an extended family presenting with a myopathy typically manifesting as upper eye lid ptosis, quadriceps atrophy and patellar dislocation. Three affected members underwent extensive genetic testing and have a RYR1 exon 46 c.7354C>T gene mutation; two of whom had muscle biopsies--both demonstrated central core myopathy. The only affected family member who underwent testing for malignant hyperthermia susceptibility was shown to be positive. The clinical phenotypes seen among affected family members varies widely in severity, and have features in common with those congenital myopathies associated with malignant hyperthermia susceptibility, raising the possibility that these conditions represent a spectrum of disease.

Variation in complement component C1 inhibitor in age-related macular degeneration

This study assessed variation in plasma levels of the complement regulatorC1 inhibitor (C1inh) in patients with age related macular degeneration (AMD) and controls. Plasma from391 AMD cases and 370 controls was assayed by rate nephelometry to determine C1inh protein levels. Protein levels were analysed for relationships with age, gender, smoking, AMD disease status and genetic variation in the SERPING1 gene, which encodes C1inh, using a multivariate analysis. t-Tests show a significant difference in C1inh levels in AMD cases compared with controls (p=2.340E-6), smokers compared to non-smokers (p=1.022E-4) and females compared to males (p=1.661E-7). Multivariate analysis shows that after accounting for gender and smoking AMD status remained significant. Age was included in the model but was not significant. Including genetic variation in the model shows that one significant SNP (rs2649663) 5' of the SERPING1 gene is associated with C1inh levels though this SNP is not associated with AMD. This suggests that genetic variation in the promoter region of the SERPING1 gene may influence expression of the gene.

Age-related macular degeneration and the complement system

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. It is a complex multifactorial disease, and despite new advances in treatment, many patients still succumb to visual impairment. The complement pathway has been implicated in the pathogenesis of many diseases, and recently variants in several genes encoding complement pathway proteins have been associated with AMD. Complement proteins have been found in histological specimens of eyes with AMD. Altered levels of both intrinsic complement proteins and activated products have been found in the circulation of patients with AMD. Complement activation may be triggered by oxidative stress, resulting from retinal exposure to incoming light; indeed an inter-play between these two pathological processes seems to exist. Finally, complement inhibitors are currently being evaluated in clinical trials. This article reviews the role of the complement system in AMD, and the potential of complement inhibition in preventing the devastating blindness resulting from this disease.

X-linked retinoschisis maculopathy treated with topical dorzolamide, and relationship to genotype

PURPOSE

To correlate the response of topical dorzolamide (Trusopt; Merck) in patients with X-linked retinoschisis (XLRS) with genotype.

METHODS

We carried out a retrospective evaluation of four patients (seven eyes) with XLRS, treated with topical dorzolamide. The change in best-corrected visual acuity (VA) and central macular thickness (CMT; central 1 mm subfield thickness) from optical coherence tomography (OCT) was analysed over the follow-up period, using Student's t-test. Each patient also had genetic analysis for mutations in the retinoschisisgene (RS1).

RESULTS

The mean age at the start of treatment was 14.7±11 years, and mean follow-up duration was 21.7±7.7 months. Mean CMT at the final follow-up was significantly better than at baseline (291±123 vs 352±119 μm, P=0.007); however, mean VA was worse (0.38±0.25 vs 0.31±0.24 logMAR score, P=0.041). All four patients had a mutation in the RS1gene; there was no apparent association between the type of mutation and the response to topical dorzolamide.

CONCLUSION

Topical dorzolamide may have some effect in reducing central macular thickness in patients with XLRS, but this does not necessarily correlate with improvement in VA. In our case series, genotypic information did not predict the response to this treatment.

Interleukin-8 promoter polymorphism -251A/T is a risk factor for age-related macular degeneration

BACKGROUND/AIMS

To determine whether four expression-related cytokine polymorphisms are associated with age-related macular degeneration (AMD).

METHODS

DNA from 478 cases with AMD and 555 normal controls was genotyped for the pro-inflammatory IL1beta -511C/T, IL6 -174C/G, IL8 -251A/T and anti-inflammatory IL10 -1082G/A cytokine polymorphisms using the 5' nuclease TaqMan(R) assay for allelic discrimination. Associations with AMD were analysed using allelic frequencies.

RESULTS

The -251A allele of the IL8 promoter gene polymorphism was more prevalent in AMD patients than controls (p = 0.037, OR = 1.21, 95% CI = 1.01 to 1.44). Adjusting for age, sex, body mass index (BMI), current smoking and past smoking status did not alter the AMD association significantly (corrected p value = 0.043, OR = 1.23, 95% CI = 1.0 to 1.50).

CONCLUSION

The pro-inflammatory homozygous IL8 -251AA genotype is an important risk factor for AMD. This may have implications for future therapy with biological agents that could target this cytokine.

An analysis of the CFH Y402H genotype in AMD patients and controls from the UK, and response to PDT treatment

AIM

Mutation in the complement factor H (CFH) gene is an important risk factor for age-related macular degeneration (AMD). In this study, we identified the strength of the CFH Y402H gene variant association in a UK AMD cohort and tested the hypothesis that this variant may influence the biological response of choroidal neovascularisation (CNV) following photodynamic therapy (PDT) for CNV.

METHODS

A total of 557 cases with AMD and 551 normal controls were genotyped for the CFH Y402H (1277 C/T) variant using the 5' nuclease TaqMan assay for allelic discrimination. The CFH gene association for AMD, for the different CNV subtypes and for patients needing PDT was estimated. Twenty-seven PDT-treated patients were followed up for 15 months with ETDRS-derived vision, clinical examination, and fundus angiography. Individuals with different CFH genotypes were then analysed for any association with visual change following PDT.

RESULTS

The risk association for AMD with the CFH CC genotype (odd ratio (OR)=3.62, Pc<0.0001) was similar to that reported in other Caucasian cohorts. The magnitude and strength of this association was stronger in AREDS stages 2-4 (ORs=4.48, 2.69, and 5.17). ORs for the risk of predominantly classic CNV were significantly raised for both the CC (OR=17.87, P<0.0001) and CT (OR=9.06, P=0.0002) genotypes. The number of patients carrying the high-risk C allele was 70.4% in those requiring PDT as compared to 52.3% in the non-PDT group (OR=2.16, P=0.011), and presence of the CC genotype significantly increased the risk of PDT (OR=5.48, P=0.015). The degree of visual loss following PDT was significantly higher in the CFH CC genotype group (P=0.038); 50% of CC cases (n=13) and 45% of the CT cases (n=12) lost 15 or more ETDRS letters at final follow-up.

CONCLUSION

In this UK cohort of AMD patients, the CFH Y402H variant was significantly enriched in patients with predominantly classic CNV. Patients homozygous for the CFH Y402H genotype seem to have worse visual acuity after PDT.

HLA and eye disease: a synopsis

Human leukocyte antigen (HLA) gene products have been implicated in the pathogenesis of an increasing number of eye diseases, mainly inflammatory in nature. This perspective reviews the current hypotheses for why HLA polymorphisms are associated with specific eye diseases. Statistical problems in studies involving HLA associations are discussed, and possible solutions outlined. The relevance of HLA testing in routine ophthalmic practice, its practical and cost implications is also assessed.

CRB1 mutations may result in retinitis pigmentosa without para-arteriolar RPE preservation

PURPOSE

To report a new phenotype in retinitis pigmentosa (RP) patients with CRB1 mutations at the RP12 locus.

PATIENTS

Thirty-seven patients from two Pakistani families with severe retinitis pigmentosa.

METHODS

Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of the coding sequence of the CRB1 gene.

RESULTS

Two novel CRB1 mutations were discovered. No patients had evidence of preservation of the para-arteriolar retinal pigment epithelium (PPRPE) that has been previously reported in all cases of RP associated with CRB1 mutations.

CONCLUSIONS

Patients with severe autosomal recessive (or simplex) RP who lack the finding of PPRPE should not be excluded from molecular analysis of CRB1 purely because they lack the clinical feature of PPRPE. This report illustrates that RP at the RP12 locus is not clinically uniform. The absence of PPRPE cannot be used to exclude CRB1 as a potential molecular explanation for RP.

Variation of codons 1961 and 2177 of the Stargardt disease gene is not associated with age-related macular degeneration

OBJECTIVES

To investigate the role of 2 specific alleles of the Stargardt disease gene (ABCA4) in the pathogenesis of age-related macular degeneration (AMD). Secondary objectives were to investigate differences in frequency of the G1961E allele in selected ethnic groups as well as to examine the segregation of both G1961E and D2177N alleles in 5 multiplex families with AMD.

METHODS

Five hundred forty-four patients with AMD and 689 controls were ascertained from 3 continents. Blood samples from 62 normal individuals of Somalian ancestry were also obtained. Participants were screened for the presence of these ABCA4 alleles with a combination of restriction digestion and single-strand conformation polymorphism analysis of polymerase chain reaction amplification products. Detected alleles were confirmed by DNA sequencing. The number of subjects exhibiting the G1961E or D2177N variants were compared between AMD and control groups using a 2-tailed Fisher exact test.

RESULTS

There was no significant difference (P >.1) in the frequency of the G1961E and D2177N alleles in patients with AMD (2.2%) vs controls (1.0%). In contrast, there was a significant difference (P< .001) in the frequency of the G1961E alleles between normal individuals of Somali ancestry (11.3%) and normal individuals from other populations (0.4%). There was no evidence of cosegregation of these alleles and the AMD phenotype in the 5 multiplex families with AMD examined. These two ABCA4 alleles were slightly more frequent in patients with AMD with choroidal neovascularization (2.7%) than those without this complication (2.5%).

CONCLUSIONS

Somali ancestry is more than 100 times more strongly associated with presence of the G1961E allele than the AMD phenotype. This study did not find any statistically significant evidence for involvement of the G1961E or D2177N alleles of the ABCA4 gene in AMD.

CLINICAL RELEVANCE

The ABCA4 gene is definitively involved in the pathogenesis of Stargardt disease and some cases of photoreceptor degeneration. However, it does not seem to be involved in a statistically significant fraction of AMD cases.

An analysis of allelic variation in the ABCA4 gene

PURPOSE

To assess the allelic variation of the ATP-binding transporter protein (ABCA4).

METHODS

A combination of single-strand conformation polymorphism (SSCP) and automated DNA sequencing was used to systematically screen this gene for sequence variations in 374 unrelated probands with a clinical diagnosis of Stargardt disease, 182 patients with age-related macular degeneration (AMD), and 96 normal subjects.

RESULTS

There was no significant difference in the proportion of any single variant or class of variant between the control and AMD groups. In contrast, truncating variants, amino acid substitutions, synonymous codon changes, and intronic variants were significantly enriched in patients with Stargardt disease when compared with their presence in subjects without Stargardt disease (Kruskal-Wallis P < 0.0001 for each variant group). Overall, there were 2480 instances of 213 different variants in the ABCA4 gene, including 589 instances of 97 amino acid substitutions, and 45 instances of 33 truncating variants.

CONCLUSIONS

Of the 97 amino acid substitutions, 11 occurred at a frequency that made them unlikely to be high-penetrance recessive disease-causing variants (HPRDCV). After accounting for variants in cis, one or more changes that were compatible with HPRDCV were found on 35% of all Stargardt-associated alleles overall. The nucleotide diversity of the ABCA4 coding region, a collective measure of the number and prevalence of polymorphic sites in a region of DNA, was found to be 1.28, a value that is 9 to 400 times greater than that of two other macular disease genes that were examined in a similar fashion (VMD2 and EFEMP1).

Mutations in the CRB1 gene cause Leber congenital amaurosis

OBJECTIVES

To test the hypothesis that mutations in the CRB1 gene cause Leber congenital amaurosis (LCA) and, if so, to describe the ocular phenotype of patients with LCA who harbor CRB1 sequence variations.

PATIENTS

One hundred ninety probands with a clinical diagnosis of LCA were selected from a cohort of 233 probands ascertained in 5 different countries. The remaining 43 probands (18%) were excluded because they harbored sequence variations in previously identified LCA genes.

METHODS

One hundred ninety unrelated individuals with LCA were screened for coding sequence mutations in the CRB1 gene with single-strand conformation polymorphism analysis followed by automated DNA sequencing.

RESULTS

Twenty-one of the 190 probands (9% of the total cohort of 233) and 2 (1.4%) of 140 controls harbored amino acid-altering sequence variations in the CRB1 gene (P =.003).

CONCLUSIONS

In our cohort of patients with LCA, coding sequence variations were observed in the CRB1 gene more frequently than in any of the other 5 known LCA-associated genes. Likely disease-causing sequence variations have now been identified in 64 (28%) of 233 subjects in this cohort.

CLINICAL RELEVANCE

Molecular diagnosis can confirm and clarify the diagnosis in an increasing fraction of patients with LCA. As genotype data accumulate, clinical phenotypes associated with specific mutations may be established. This will facilitate the counseling of patients regarding their visual prognosis and the likelihood of associated systemic anomalies.

Electrophysiology findings in a large family with central areolar choroidal dystrophy

PURPOSE

To perform an electrophysiological study of central areolar choroidal dystrophy (CACD) in the affected members of a four generation family.

METHODS

Eight affected family members from the last three generations of a family affected by CACD were assessed by full-field electroretinograms (rod response, maximal combined response, oscillatory potentials, single-flash cone response and 30 Hz flicker responses) and electro-oculograms. In addition three members of the youngest generation, who were visually asymptomatic, had pattern visual evoked potentials (PVEPs) and pattern electroretinograms (PERGs) performed. Affected status had been determined previously by genetic analysis.

RESULTS

Three youngest generation family members, who were considered affected by genetic haplotype analysis, had no visible optic nerve or retinal abnormalities. All of these subjects had abnormal PVEPs and PERGs in both eyes. Abnormalities were also detected in two of these subject's Rod ERGs, Cone ERGs and one of these subject's Maximal ERGs and 30 Hz ERGs. Electrophysiological examination in the older generations demonstrated a similar, more advanced, cone and rod dysfunction.

CONCLUSIONS

All affected, but clinically normal, youngest generation patients had bilaterally abnormal PVEPs and PERGs. In CACD the PVEP and PERG proved to be the most sensitive electrophysiological tests of preclincial macular dysfunction, 3/3 subjects abnormal. ERG recording to ISCEV guidelines were very useful in these cases; 7/8 subjects abnormal. The EOG was less useful; 4/8 subjects abnormal. CACD produces a widespread photoreceptor dysfunction in its later stages.

Correctable visual impairment in stroke rehabilitation patients

BACKGROUND

after stroke, visual impairment may exacerbate the impact of other impairments on overall disability and negatively influence rehabilitation.

OBJECTIVE

to examine the visual status of patients after stroke and determine whether this can be improved by simple interventions.

DESIGN

prospective study.

SETTINGS

stroke rehabilitation unit in a Belfast teaching hospital.

SUBJECTS

77 consecutive patients admitted for rehabilitation after acute stroke.

METHODS

full optometric and ophthalmic assessment within 2 weeks of admission.

RESULTS

of 70 patients with glasses, 19 did not have their glasses in hospital before prompting and 18 had glasses in unacceptable condition. Twenty patients had impaired visual acuity (6/12 or worse) with existing glasses (if helpful); 11 of these improved to better than 6/12 with refractive correction.

CONCLUSIONS

stroke professionals need to enquire about patients' spectacles and assess their condition. Patients with reduced visual acuity in the absence of significant non-refractive disease should be referred to an optometrist: in this series 14% of patients had visual impairment which benefited from refractive correction.

Allelic variation in the VMD2 gene in best disease and age-related macular degeneration

PURPOSE

To assess the allelic variation of the VMD2 gene in patients with Best disease and age-related macular degeneration (AMD).

METHODS

Three hundred twenty-one AMD patients, 192 ethnically similar control subjects, 39 unrelated probands with familial Best disease, and 57 unrelated probands with the ophthalmoscopic findings of Best disease but no family history were screened for sequence variations in the VMD2 gene by single-strand conformation polymorphism (SSCP) analysis. Amplimers showing a bandshift were reamplified and sequenced bidirectionally. In addition, the coding regions of the VMD2 gene were completely sequenced in six probands with familial Best disease who showed no SSCP shift.

RESULTS

Forty different probable or possible disease-causing mutations were found in one or more Best disease or AMD patients. Twenty-nine of these variations are novel. Of the 39 probands with familial Best disease, mutations were detected in all 39 (33 by SSCP and 6 by DNA sequencing). SSCP screening of the 57 probands with a clinical diagnosis of Best disease but no family history revealed 16 with mutations. Mutations were found in 5 of 321 AMD patients (1.5%), a fraction that was not significantly greater than in control individuals (0/192, 0%).

CONCLUSIONS

Patients with the clinical diagnosis of Best disease are significantly more likely to have a mutation in the VMD2 gene if they also have a positive family history. These findings suggest that a small fraction of patients with the clinical diagnosis of AMD may actually have a late-onset variant of Best disease, whereas at the same time, a considerable fraction of isolated patients with the ophthalmoscopic features of Best disease are probably affected with some other macular disease.

Mutation analysis of 3 genes in patients with Leber congenital amaurosis

OBJECTIVE

To assess the frequency of mutations in the CRX, GUCY2D, and RPE65 genes in patients with Leber congenital amaurosis (LCA).

PATIENTS

One hundred seventy-six probands with a clinical diagnosis of LCA were from 9 countries, with the largest subgroup being 39 probands from India.

METHODS

Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of 3 genes (CRX, GUCY2D, and RPE65) known to be associated with LCA.

RESULTS

Of the 176 probands, 28 (15.9%) harbored possible disease-causing mutations. The relative contribution of each gene to the total number of mutations was as follows: CRX, 2.8%; GUCY2D, 6.3%; and RPE65, 6.8%. No patients who harbored mutations in these genes had associated systemic abnormalities. Molecular diagnosis allowed definitive genetic counseling in a family affected with Best disease and LCA.

CONCLUSIONS

Molecular diagnosis may be of benefit to patients affected with LCA. The relative paucity of mutations found in this study suggests that more LCA-associated genes remain to be discovered.

CLINICAL RELEVANCE

Molecular diagnosis can confirm and clarify the diagnosis of LCA. As genotype data accumulate, clinical phenotypes associated with specific mutations will be established. This will facilitate the counseling of patients on their visual prognosis and the likelihood of associated systemic anomalies.