Diabetic Macular Edema and Diode Subthreshold Micropulse Laser: A Randomized Double-Masked Noninferiority Clinical Trial.

PURPOSE: To determine clinical effectiveness, safety, and cost-effectiveness of subthreshold micropulse laser (SML), compared with standard laser (SL), for diabetic macular edema (DME) with central retinal thickness (CRT) < 400 µm. DESIGN: Pragmatic, multicenter, allocation-concealed, double-masked, randomized, noninferiority trial. PARTICIPANTS: Adults with center-involved DME < 400 µm and best-corrected visual acuity (BCVA) of > 24 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in one/both eyes. METHODS: Randomization 1:1 to 577 nm SML or SL treatment. Retreatments were allowed. Rescue with intravitreal anti-vascular endothelial growth factor therapies or steroids was permitted if 10 or more ETDRS letter loss occurred, CRT increased > 400 µm, or both. MAIN OUTCOME MEASURES: Primary outcome was mean change in BCVA in the study eye at 24 months (noninferiority margin 5 ETDRS letters). Secondary outcomes were mean change from baseline to month 24 in binocular BCVA; CRT and mean deviation of Humphrey 10-2 visual field in the study eye; percentage meeting driving standards; EuroQoL EQ-5D-5L, 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25), and Vision and Quality of Life Index (VisQoL) scores; cost per quality-adjusted life-years (QALYs) gained; adverse effects; and number of laser and rescue treatments. RESULTS: The study recruited fully (n = 266); 87% of SML-treated and 86% of SL-treated patients had primary outcome data. Mean ± standard deviation BCVA change from baseline to month 24 was -2.43 ± 8.20 letters and -0.45 ± 6.72 letters in the SML and SL groups, respectively. Subthreshold micropulse laser therapy was deemed not only noninferior but also equivalent to SL therapy because the 95% confidence interval (CI; -3.9 to -0.04 letters) lay wholly within both upper and lower margins of the permitted maximum difference (5 ETDRS letters). No statistically significant difference was found in binocular BCVA (0.32 ETDRS letters; 95% CI, -0.99 to 1.64 ETDRS letters; P = 0.63); CRT (-0.64 µm; 95% CI, -14.25 to 12.98 µm; P = 0.93); mean deviation of the visual field (0.39 decibels (dB); 95% CI, -0.23 to 1.02 dB; P = 0.21); meeting driving standards (percentage point difference, 1.6%; 95% CI, -25.3% to 28.5%; P = 0.91); adverse effects (risk ratio, 0.28; 95% CI, 0.06-1.34; P = 0.11); rescue treatments (percentage point difference, -2.8%; 95% CI, -13.1% to 7.5%; P = 0.59); or EQ-5D, NEI-VFQ-25, or VisQoL scores. Number of laser treatments was higher in the SML group (0.48; 95% CI, 0.18-0.79; P = 0.002). Base-case analysis indicated no differences in costs or QALYs. CONCLUSIONS: Subthreshold micropulse laser therapy was equivalent to SL therapy, requiring slightly higher laser treatments.

Standard threshold laser versus subthreshold micropulse laser for adults with diabetic macular oedema: the DIAMONDS non-inferiority RCT.

BACKGROUND: The National Institute for Health and Care Excellence recommends macular laser to treat diabetic macular oedema with a central retinal subfield thickness of < 400 µm on optical coherence tomography. The DIAMONDS (DIAbetic Macular Oedema aNd Diode Subthreshold micropulse laser) trial compared standard threshold macular laser with subthreshold micropulse laser to treat diabetic macular oedema suitable for macular laser. OBJECTIVES: Determining the clinical effectiveness, safety and cost-effectiveness of subthreshold micropulse laser compared with standard threshold macular laser to treat diabetic macular oedema with a central retinal subfield thickness of < 400 µm. DESIGN: A pragmatic, multicentre, allocation-concealed, double-masked, randomised, non-inferiority, clinical trial. SETTING: Hospital eye services in the UK. PARTICIPANTS: Adults with diabetes and centre-involving diabetic macular oedema with a central retinal subfield thickness of < 400 µm, and a visual acuity of > 24 Early Treatment Diabetic Retinopathy Study letters (Snellen equivalent > 20/320) in one/both eyes. INTERVENTIONS: Participants were randomised 1 : 1 to receive 577 nm subthreshold micropulse laser or standard threshold macular laser (e.g. argon laser, frequency-doubled neodymium-doped yttrium aluminium garnet 532 nm laser); laser treatments could be repeated as needed. Rescue therapy with intravitreal anti-vascular endothelial growth factor therapies or steroids was allowed if a loss of ≥ 10 Early Treatment Diabetic Retinopathy Study letters between visits occurred and/or central retinal subfield thickness increased to > 400 µm. MAIN OUTCOME MEASURES: The primary outcome was the mean change in best-corrected visual acuity in the study eye at 24 months (non-inferiority margin 5 Early Treatment Diabetic Retinopathy Study letters). Secondary outcomes included the mean change from baseline to 24 months in the following: binocular best-corrected visual acuity; central retinal subfield thickness; the mean deviation of the Humphrey 10-2 visual field in the study eye; the percentage of people meeting driving standards; and the EuroQol-5 Dimensions, five-level version, National Eye Institute Visual Function Questionnaire - 25 and Vision and Quality of Life Index scores. Other secondary outcomes were the cost per quality-adjusted life-years gained, adverse effects, number of laser treatments and additional rescue treatments. RESULTS: The DIAMONDS trial recruited fully (n = 266); 87% of participants in the subthreshold micropulse laser group and 86% of participants in the standard threshold macular laser group had primary outcome data. Groups were balanced regarding baseline characteristics. Mean best-corrected visual acuity change in the study eye from baseline to month 24 was -2.43 letters (standard deviation 8.20 letters) in the subthreshold micropulse laser group and -0.45 letters (standard deviation 6.72 letters) in the standard threshold macular laser group. Subthreshold micropulse laser was deemed to be not only non-inferior but also equivalent to standard threshold macular laser as the 95% confidence interval (-3.9 to -0.04 letters) lay wholly within both the upper and lower margins of the permitted maximum difference (5 Early Treatment Diabetic Retinopathy Study letters). There was no statistically significant difference between groups in any of the secondary outcomes investigated with the exception of the number of laser treatments performed, which was slightly higher in the subthreshold micropulse laser group (mean difference 0.48, 95% confidence interval 0.18 to 0.79; p = 0.002). Base-case analysis indicated no significant difference in the cost per quality-adjusted life-years between groups. FUTURE WORK: A trial in people with ≥ 400 µm diabetic macular oedema comparing anti-vascular endothelial growth factor therapy alone with anti-vascular endothelial growth factor therapy and macular laser applied at the time when central retinal subfield thickness has decreased to < 400 µm following anti-vascular endothelial growth factor injections would be of value because it could reduce the number of injections and, subsequently, costs and risks and inconvenience to patients. LIMITATIONS: The majority of participants enrolled had poorly controlled diabetes. CONCLUSIONS: Subthreshold micropulse laser was equivalent to standard threshold macular laser but required a slightly higher number of laser treatments. TRIAL REGISTRATION: This trial is registered as EudraCT 2015-001940-12, ISRCTN17742985 and NCT03690050. FUNDING: This project was funded by the National Institute for Health and Care Research ( NIHR ) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 50. See the NIHR Journals Library website for further project information.

The retina is a layer at the back of the eye. Its centre is called the macula and is responsible for central vision. Some people with diabetes develop diabetic macular oedema. In diabetic macular oedema fluid leaks from retinal blood vessels and builds up at the macula, resulting in sight loss. Diabetic macular oedema can be mild or severe; this can be determined measuring the thickness of the macula, which is measured in micrometres (µm). One micrometre is one thousandth of a millimetre. In mild diabetic macular oedema, the thickness of the macula increases, but is less than 400 µm. Patients with mild diabetic macular oedema can be treated with a laser and there are two laser types. The standard threshold macular laser has been available for many years. It clears the diabetic macular oedema but produces a 'burn' in the retina. The subthreshold micropulse laser is newer. It does not produce a burn but also clears the diabetic macular oedema. The lack of a burn, however, has led to doubts about whether or not this laser works as well as the standard threshold macular laser because 'no burn' was taken to mean 'less benefit'. These doubts led to our establishing the DIAMONDS (DIAbetic Macular Oedema aNd Diode Subthreshold micropulse laser) trial, which compared these two lasers for people with mild diabetic macular oedema. A total of 266 people suitable for either laser joined the study at 16 NHS hospitals across the UK; 133 received standard threshold macular laser and 133 received subthreshold micropulse laser. The choice of laser was determined by chance. The DIAMONDS trial found that the subthreshold micropulse laser was as good as the standard threshold macular laser (i.e. 'clinically equivalent') in terms of improving people's vision, reducing macula thickness, allowing people to meet driving standards and maintaining their quality of life, both in general terms and for vision in particular. There was a small increase (less than one session on average per person) in the number of laser treatment sessions needed with subthreshold micropulse laser. The costs of both laser treatments were about the same.

Importance of Anatomical Efficacy for Disease Control in Neovascular AMD: An Expert Opinion.

BACKGROUND: Neovascular age-related macular degeneration (nAMD) presents a significant treatment burden for patients, carers and medical retina services. However, significant debate remains regarding how best to manage nAMD when assessing disease activity by optical coherence tomography (OCT), and particularly the significance of different types of fluid and how the understanding of anatomical efficacy can influence treatment strategies. This article provides opinion on the practical implications of anatomical efficacy and significance of fluid in the management of nAMD and proposes recommendations for healthcare professionals (HCPs) to improve understanding and promote best practice to achieve disease control. METHODS: An evidence-based review was performed and an expert panel debate from the Retina Outcomes Group (ROG), a forum of retinal specialists, provided insights and recommendations on the definition, role and practical implications of anatomical efficacy and the significance of fluid at the macula in the management of nAMD. RESULTS: The ROG has developed recommendations for achieving disease control through a zero-tolerance approach to the presence of fluid in nAMD as patients who avoid fluctuations in fluid at the macula have better visual outcomes. Recommendations cover five key areas: service protocol, training, regimen, multidisciplinary teams and engagement. This approach facilitates more standardised protocol-based treatment strategies. CONCLUSIONS: Targeting a fluid-free macula and aiming for disease control are essential to improve outcomes. As new therapies and technologies become available, drying the macula and maintaining disease control will become even more achievable. The outlined recommendations aim to promote best practice among HCPs and medical retina services to improve patient outcomes.

Restructuring Wet Age-Related Macular Degeneration Services During the COVID-19 Pandemic to Allow Social Distancing Outpatient Clinics (SDOC).

BACKGROUND: COVID-19 has had a major impact on health-care provision. Social distancing will impact the organization of outpatient clinics (OCs) and require general restructuring of health care. METHODS: Our retinal team participated in a structured fact-finding session to implement social distancing of patients and staff in wet age-related macular degeneration (wAMD) clinics. Clinic flow and performance were continually reviewed and improved. A retrospective audit of all wAMD follow-up appointments was conducted for 4 weeks from the start of the UK lockdown. A search for clinical guidance regarding retinal services was performed on the homepages of international professional bodies. The guidelines were compared to the implemented changes in our wAMD social distancing OCs (SDOCs) and potential risk examined. RESULTS: The changes in clinic setup to achieve SDOCs are described. The average total time spent in the clinic area by each patient has reduced by 27%. The audit concluded that 65% of patients needed a treatment interval of 4-7 weeks after their appointment, 17% at either 8 or 9 weeks, and 18% at 10 weeks or beyond. The UK, Australian-New Zealand, US, and German professional ophthalmology bodies have published divergent guidelines, but all recommended a continuation of anti-VEGF injections. CONCLUSION: Health-care provision will change and hospitals and outpatient facilities will have to adapt to the COVID-19 epidemic. We describe a clinic setup (SDOCs) that minimizes risk to patients and staff, while maintaining the ability to treat each patient and their disease individually.

Binocular Visual Function in a Pre-Presbyopic Patient with Uniocular Cataract Undergoing Cataract Surgery with a Multifocal Intraocular Lens.

BACKGROUND/AIM: An increasing number of pre-presbyopic patients are undergoing uniocular cataract extraction. We aim to compare the binocular status of subjects with uniocular cataracts, implanted either with a multifocal or a monofocal intraocular lens (IOL). MATERIALS AND METHODS: Subjects were recruited from outpatient ophthalmology clinics and randomized to an IOL type. Corrected and uncorrected LogMAR distance visual acuity (VA) and near and intermediate VA using the Radner reading test were completed. The binocular tests included the Worth Four Dot Test, fixation disparity, TNO stereoacuity and foveal suppression assessment. In addition to the near activity vision questionnaire. The trial was closed early because the chosen multifocal lens had been superseded by newer models. We report two subjects, one receiving the multifocal IOL and a monofocal IOL control with the most comparable baseline characteristics. RESULTS: Both subjects experienced uncomplicated cataract surgery, showing clinically significant improved corrected distance VA, 0.06 LogMAR and -0.16 LogMAR in the monofocal and multifocal IOL, respectively. The multifocal subject had 30 seconds of arc stereoacuity indicating normal binocular vision. Only gross binocular single vision with no stereopsis was found in the monofocal IOL subject. The latter subject also had reduced near vision quality-of-life questionnaire results. CONCLUSION: This two-patient case series demonstrates greater binocular near ability, with the multifocal IOL, in the pre-presbyopic patient undergoing uniocular cataract surgery. The case series highlights the need, and methodology for investigating further the functional and quality-of-life benefits of implanting multifocal IOLs in pre-presbyopic patients, those in their twenties and thirties, undergoing uniocular cataract surgery.

Diabetic macular oedema and diode subthreshold micropulse laser (DIAMONDS): study protocol for a randomised controlled trial.

BACKGROUND: In the UK, macular laser is the treatment of choice for people with diabetic macular oedema with central retinal subfield thickness (CST) < 400 µm, as per National Institute for Health and Care Excellence guidelines. It remains unclear whether subthreshold micropulse laser is superior and should replace standard threshold laser for the treatment of eligible patients. METHODS: DIAMONDS is a pragmatic, multicentre, allocation-concealed, randomised, equivalence, double-masked clinical trial that aims to determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser compared with standard threshold laser, for the treatment of diabetic macular oedema with CST < 400 µm. The primary outcome is the mean change in best-corrected visual acuity in the study eye from baseline to month 24 post treatment. Secondary outcomes (at 24 months) include change in binocular best corrected visual acuity; CST; mean deviation of the Humphrey 10-2 visual field; change in percentage of people meeting driving standards; European Quality of Life-5 Dimensions, National Eye Institute Visual Functioning Questionnaire-25 and VisQoL scores; incremental cost per quality-adjusted life year gained; side effects; number of laser treatments and use of additional therapies. The primary statistical analysis will be per protocol rather than intention-to-treat analysis because the latter increases type I error in non-inferiority or equivalence trials. The difference between lasers for change in best-corrected visual acuity (using 95% CI) will be compared to the permitted maximum difference of five Early Treatment Diabetic Retinopathy Study (ETDRS) letters. Linear and logistic regression models will be used to compare outcomes between treatment groups. A Markov-model-based cost-utility analysis will extend beyond the trial period to estimate longer-term cost-effectiveness. DISCUSSION: This trial will determine the clinical effectiveness and cost-effectiveness of subthreshold micropulse laser, when compared with standard threshold laser, for the treatment of diabetic macular oedema, the main cause of sight loss in people with diabetes mellitus. TRIAL REGISTRATION: International Standard Randomised Controlled Trials, ISRCTN17742985 . Registered on 19 May 2017 (retrospectively registered).

Beneficial effects on vision in patients undergoing retinal gene therapy for choroideremia.

Retinal gene therapy is increasingly recognized as a novel molecular intervention that has huge potential in treating common causes of blindness, the majority of which have a genetic aetiology1-5. Choroideremia is a chronic X-linked retinal degeneration that was first described in 18726. It leads to progressive blindness due to deficiency of Rab-escort protein 1 (REP1). We designed an adeno-associated viral vector to express REP1 and assessed it in a gene therapy clinical trial by subretinal injection in 14 patients with choroideremia. The primary endpoint was vision change in treated eyes 2 years after surgery compared to unoperated fellow eyes. Despite complications in two patients, visual acuity improved in the 14 treated eyes over controls (median 4.5 letter gain, versus 1.5 letter loss, P = 0.04), with 6 treated eyes gaining more than one line of vision (>5 letters). The results suggest that retinal gene therapy can sustain and improve visual acuity in a cohort of predominantly late-stage choroideremia patients in whom rapid visual acuity loss would ordinarily be predicted.

Initiation and maintenance of a Treat-and-Extend regimen for ranibizumab therapy in wet age-related macular degeneration: recommendations from the UK Retinal Outcomes Group.

The treatment of neovascular (wet) age-related macular degeneration (AMD) with ranibizumab is now very well established in terms of efficacy and safety. Recent clinical trials and real-world studies have demonstrated the advantages of a Treat-and-Extend (T&E) regimen, and many hospital departments are now in the process of adopting this new regimen in favor of the pro re nata regimen for initiating and continuing ranibizumab therapy for patients with wet AMD. The comprehensive spectrum of issues related to implementation of the regimen is covered qualitatively in ten didactic topics provided by a group of clinicians with direct experience of this regimen in their department. The topics include definition, new and previously treated eyes, management of high-frequency injections, maximum extensions, discontinuing T&E, bilateral cases, clerical, audit, and patient counseling. This article aims to provide a useful resource for the implementation of the T&E regimen. A quantitative summary of the visual outcomes in key publications is also provided in this article. This article should be a valuable resource for staff training.

Optical Coherence Tomography in Patients With the Subretinal Implant Retina Implant Alpha IMS.

BACKGROUND AND OBJECTIVE: The aim of this study was to assess changes in retinal structure and thickness after subretinal implantation of the Retina Implant Alpha IMS (Retina Implant AG, Reutlingen, Germany). PATIENTS AND METHODS: Spectral-domain optical coherence tomography (SD-OCT) imaging was performed to assess the structure and thickness of the retina anterior to the microphotodiode array preoperatively, within 6 weeks and 6 months ± 1 month after implantation. Thickness measurements were performed using the distance tool of the built-in software. Three thickness measurements were performed in each of the four quadrants of the retina on the microchip within 6 weeks and 6 months ± 1 month after implantation. RESULTS: The mean ± standard deviation change in retinal thickness from within 6 weeks to 6 months ± 1 month after implantation in all four quadrants combined was 24 µm ± 68 µm. None of the tested variables (location, time, or their interaction) had a statistically significant effect on the mean retinal thickness (P = .961, P = .131, and P = .182, respectively; n = 19). CONCLUSION: The authors report on qualitative and quantitative findings in retinal structure in 27 patients after subretinal implantation of the Retina Implant Alpha IMS using OCT technology. No significant changes of retinal thickness could be observed in a period of 6 months after surgery. With more patients receiving subretinal implants and with advanced OCT technology, the data set will be extended to study possible changes in retinal structure in finer detail. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:993-999.].

Characterizing the Natural History of Visual Function in Choroideremia Using Microperimetry and Multimodal Retinal Imaging.

Purpose: Centripetal retinal degeneration in choroideremia (CHM) leads to early visual field restriction and late central vision loss. The latter marks an acute decline in quality of life but visual prognostication remains challenging. We investigated visual function in CHM by correlating best-corrected visual acuity (BCVA), microperimetry and multimodal imaging. Methods: Fifty-six consecutive CHM patients attending Oxford Eye Hospital were examined with BCVA, 10-2 microperimetry, optical coherence tomography, and fundus autofluorescence (AF). Microperimetry was repeated in 21 eyes and analyzed with Bland-Altman. Kaplan-Meier survival plots of eyes retaining 20/20 BCVA were created. Intereye symmetry was assessed. Results: Microperimetry coefficient of repeatability was 1.45 dB. Survival analysis showed an indistinguishable pattern between eyes (median survival 39 years). Macular sensitivity showed a similar decline in right and left eyes, with half-lives of 13.6 years. Zonal analysis showed faster decline nasal to the fovea. Intereye symmetry was more consistent for microperimetry sensitivity (r = 0.95, P < 0.001) than BCVA (r = 0.42, P = 0.0006). Near normal foveal sensitivity was maintained when the fovea was at least 2500 µm from the advancing edge of AF. Conclusions: BCVA is a marker of central degeneration and can provide valuable information about the position of the remaining retina as well as a measure of the impact on daily living. Microperimetry represents the global macular region. Both visual functions showed a high degree of intereye symmetry, particularly in early stages, indicating the fellow eye can provide a suitable control for assessing interventions to one eye. The findings may help to tailor visual prognosis and interpret outcomes of trials.

The Spectrum of CHM Gene Mutations in Choroideremia and Their Relationship to Clinical Phenotype.

PURPOSE: We report the underlying genotype and explore possible genotypic-phenotypic correlations in a large cohort of choroideremia patients. METHODS: We studied prospectively a cohort of 79 patients diagnosed within a tertiary referral service for patients with retinal dystrophies. Phenotypic evaluation consisted of clinical examination, including visual acuity and residual retinal area by fundus autofluorescence (FAF). Genotype was established by sequencing. We also investigated whether particular genotypes were associated with more severe phenotypes by performing analysis of covariance (ANCOVA), with visual acuity and FAF as the dependent variables and age as the covariant. RESULTS: A total of 74 (94%) of patients in our cohort had causative mutations by sequencing, the majority of which were anticipated to be null. Of these, 35 (47%) had insertions and deletions, 13 (18%) had mutations predicted to affect splicing, and 26 (35%) had single point mutations. In the latter case, 13 of 21 (62%) pedigrees with single point mutations were C to T transitions at C-phosphate-G (CpG) dinucleotides. These mutations were spread across 5 of only 24 CpG dinucleotides in the entire CHM cDNA. Furthermore, these 5 locations are the only sites at which C to T transitions result in a stop codon. No clear evidence was found for genotype-phenotype correlation except in the instance of a patient with a large deletion involving neighbouring sequences. CONCLUSIONS: In patients with a diagnosis of choroideremia made by a specialty service, there is a high likelihood of establishing a genetic diagnosis. The majority of causative mutations appear to be null and, therefore, may benefit from gene replacement therapy. A disproportionate number of single point mutations observed were C to T transitions, consistent with the evolutionary decay of CpG dinucleotides through methylation and subsequent deamination. Hence, the development of choroideremia in such patients may represent the unwanted consequence of human evolution; de novo mutations are predicted to arise at these sites in future generations. (ClinicalTrials.gov number, NCT01461213.).

A Qualitative and Quantitative Assessment of Fundus Autofluorescence Patterns in Patients With Choroideremia.

PURPOSE: We set out to characterize the pattern of fundus autofluorescence (AF) loss in choroideremia (CHM) patients of varying ages and disease severity in order to determine the average rate of progression of this potential disease biomarker. METHODS: Fifty consecutive CHM patients (100 eyes) attending outpatient clinics at Oxford Eye Hospital underwent analysis with the Heidelberg OCT Spectralis with autofluorescence capabilities. The area of residual AF was traced using Heidelberg Eye Explorer. Bland-Altman analysis was used to calculate the coefficient of repeatability (CR). The degree of AF loss was correlated to different ages and the pattern of residual AF constructed into color-coded maps in order to gain insight into the mechanism of disease progression. RESULTS: The CR for measurement of AF area is <1%, indicating that a small change is likely to be significant. Correlation of patient age and area of residual AF produced a clinically relevant index of expected anatomic disease. Progression is 7.7% of the residual area each year (95% confidence intervals 7.0%-8.2%) and follows a logarithmic pattern with age (r = 0.95, P < 0.001). From this we derived the mean half-life of AF as 9 years. Qualitatively, the pattern of remaining AF centered on a point temporal to the fovea. CONCLUSIONS: The area of residual AF in CHM can be measured reproducibly and shows a distinct pattern of loss. The measured residual area is inversely correlated to age. The ratio of the two variables may provide useful information regarding the rate of progression for any one individual at a given point in time.

Correlation of Optical Coherence Tomography and Autofluorescence in the Outer Retina and Choroid of Patients With Choroideremia.

PURPOSE: To evaluate the relationships between RPE, photoreceptor, and choroidal degeneration in choroideremia. METHODS: Enhanced-depth imaging optical coherence tomography (EDI-OCT), scanning laser ophthalmoscopy (SLO), and autofluorescence (AF) were performed on 39 patients (78 eyes) with choroideremia. The edges of surviving outer retina on OCT and residual AF were aligned. The distribution of outer retinal tubulations was mapped over a range of ages (16-71 years), and comparison made between pre- and postsubretinal gene therapy. Subfoveal choroidal thickness (SFCT) was compared between 23 choroideremia patients (42 eyes) and 20 age- and refraction-matched male controls (40 eyes). RESULTS: The edges of RPE AF aligned with a reduction in outer nuclear layer thickness (Spearman's rho = 0.9992). Correlation was also found between the quality of AF and integrity of ellipsoid zone within islands of surviving retina. Tubulations existed in 71 of 78 (91%) eyes with choroideremia and remained stable following gene therapy. Subfoveal choroidal thickness was reduced at baseline in choroideremia (179.7 ± 17.2 µm) compared with controls (302.0 ± 4.8 µm; P < 0.0001), but did not undergo significant thinning until end-stage retinal degeneration (43.1 ± 6.5 µm). CONCLUSIONS: The data suggest that RPE loss is the primary cause of photoreceptor degeneration in choroideremia. The choroid is thinner than controls from early stages, in keeping with a mild developmental defect. Photoreceptors appear to lose outer segments following loss of underlying RPE and form tubulations at the edges of degeneration. The preservation of tubulations over time and after subretinal injection would be consistent with these structures maintaining attachment to the inner retina and hence being potentially light responsive (ClinicalTrials.gov, NCT01461213).

Functional Defects in Color Vision in Patients With Choroideremia.

PURPOSE: To characterize defects in color vision in patients with choroideremia. DESIGN: Prospective cohort study. METHODS: Thirty patients with choroideremia (41 eyes) and 10 age-matched male controls (19 eyes) with visual acuity of ≥6/36 attending outpatient clinics in Oxford Eye Hospital underwent color vision testing with the Farnsworth-Munsell 100 hue test, visual acuity testing, and autofluorescence imaging. To exclude changes caused by degeneration of the fovea, a subgroup of 14 patients with a visual acuity ≥6/6 was analyzed. Calculated color vision total error scores were compared between the groups and related to a range of factors using a random-effects model. RESULTS: Mean color vision total error scores were 120 (95% confidence interval [CI] 92, 156) in the ≥6/6 choroideremia group, 206 (95% CI 161, 266) in the <6/6 visual acuity choroideremia group, and 47 (95% CI 32, 69) in the control group. Covariate analysis showed a significant difference in color vision total error score between the groups (P < .001 between each group). CONCLUSIONS: Patients with choroideremia have a functional defect in color vision compared with age-matched controls. The color vision defect deteriorates as the degeneration encroaches on the fovea. The presence of an early functional defect in color vision provides a useful biomarker against which to assess successful gene transfer in gene therapy trials.

Subretinal Visual Implant Alpha IMS--Clinical trial interim report.

A subretinal visual implant (Alpha IMS, Retina Implant AG, Reutlingen, Germany) was implanted in 29 blind participants with outer retinal degeneration in an international multicenter clinical trial. Primary efficacy endpoints of the study protocol were a significant improvement of activities of daily living and mobility to be assessed by activities of daily living tasks, recognition tasks, mobility, or a combination thereof. Secondary efficacy endpoints were a significant improvement of visual acuity/light perception and/or object recognition (clinicaltrials.gov, NCT01024803). During up to 12 months observation time twenty-one participants (72%) reached the primary endpoints, of which thirteen participants (45%) reported restoration of visual function which they use in daily life. Additionally, detection, localization, and identification of objects were significantly better with the implant power switched on in the first 3 months. Twenty-five participants (86%) reached the secondary endpoints. Measurable grating acuity was up to 3.3 cycles per degree, visual acuities using standardized Landolt C-rings were 20/2000, 20/2000, 20/606 and 20/546. Maximal correct motion perception ranged from 3 to 35 degrees per second. These results show that subretinal implants can restore very-low-vision or low vision in blind (light perception or less) patients with end-stage hereditary retinal degenerations.

Gene therapy for choroideremia using an adeno-associated viral (AAV) vector.

Choroideremia is an outer retinal degeneration with a characteristic clinical appearance that was first described in the nineteenth century. The disorder begins with reduction of night vision and gradually progresses to blindness by middle age. The appearance of the fundus in sufferers is recognizable by the characteristic pale color caused by the loss of the outer retina, retinal-pigmented epithelium, and choroidal vessels, leading to exposure of the underlying sclera. Choroideremia shows X-linked recessive inheritance and the choroideremia gene (CHM) was one of the first to be identified by positional cloning in 1990. Subsequent identification and characterization of the CHM gene, which encodes Rab escort protein 1 (REP1), has led to better comprehension of the disease and enabled advances in genetic diagnosis. Despite several decades of work to understand the exact pathogenesis, no established treatments currently exist to stop or even slow the progression of retinal degeneration in choroideremia. Encouragingly, several specific molecular and clinical features make choroideremia an ideal candidate for treatment with gene therapy. This work describes the considerations and challenges in the development of a new clinical trial using adeno-associated virus (AAV) encoding the CHM gene.

Retinal gene therapy in patients with choroideremia: initial findings from a phase 1/2 clinical trial.

BACKGROUND: Choroideremia is an X-linked recessive disease that leads to blindness due to mutations in the CHM gene, which encodes the Rab escort protein 1 (REP1). We assessed the effects of retinal gene therapy with an adeno-associated viral (AAV) vector encoding REP1 (AAV.REP1) in patients with this disease. METHODS: In a multicentre clinical trial, six male patients (aged 35-63 years) with choroideremia were administered AAV.REP1 (0·6-1·0×10(10) genome particles, subfoveal injection). Visual function tests included best corrected visual acuity, microperimetry, and retinal sensitivity tests for comparison of baseline values with 6 months after surgery. This study is registered with ClinicalTrials.gov, number NCT01461213. FINDINGS: Despite undergoing retinal detachment, which normally reduces vision, two patients with advanced choroideremia who had low baseline best corrected visual acuity gained 21 letters and 11 letters (more than two and four lines of vision). Four other patients with near normal best corrected visual acuity at baseline recovered to within one to three letters. Mean gain in visual acuity overall was 3·8 letters (SE 4·1). Maximal sensitivity measured with dark-adapted microperimetry increased in the treated eyes from 23·0 dB (SE 1·1) at baseline to 25·3 dB (1·3) after treatment (increase 2·3 dB [95% CI 0·8-3·8]). In all patients, over the 6 months, the increase in retinal sensitivity in the treated eyes (mean 1·7 [SE 1·0]) was correlated with the vector dose administered per mm(2) of surviving retina (r=0·82, p=0·04). By contrast, small non-significant reductions (p>0·05) were noted in the control eyes in both maximal sensitivity (-0·8 dB [1·5]) and mean sensitivity (-1·6 dB [0·9]). One patient in whom the vector was not administered to the fovea re-established variable eccentric fixation that included the ectopic island of surviving retinal pigment epithelium that had been exposed to vector. INTERPRETATION: The initial results of this retinal gene therapy trial are consistent with improved rod and cone function that overcome any negative effects of retinal detachment. These findings lend support to further assessment of gene therapy in the treatment of choroideremia and other diseases, such as age-related macular degeneration, for which intervention should ideally be applied before the onset of retinal thinning. FUNDING: UK Department of Health and Wellcome Trust.

Macular hole surgery in patients with end-stage choroideremia.

OBJECTIVE: To assess macular hole surgery in patients with end-stage choroideremia with regard to anatomic closure and visual outcome. DESIGN: Retrospective, interventional case series. PARTICIPANTS: Thirty adult male patients with a diagnosis of advanced choroideremia were reviewed and underwent spectral domain optical coherence tomography (OCT) as part of the screening process for a gene therapy clinical trial. From within that cohort, 3 were identified as having a full-thickness macular hole (FTMH). METHODS: A 23-gauge pars plana vitrectomy was performed with peeling of the inner limiting membrane and gas tamponade. Preoperative best-corrected visual acuity ranged from perception of light to 6/24. MAIN OUTCOME MEASURES: Prevalence of FTMH in advanced choroideremia, morphologic phenotype characteristics of FTMH in OCT, pre- and postoperative best-corrected visual acuity, and closure rate after surgery. RESULTS: The prevalence of FTMH in advanced choroideremia in our cohort was 10%. One hole was associated with significant macular schisis, presumed to be attributable to degeneration of outer retinal layers. Anatomic closure was achieved in all 3 patients and confirmed with spectral domain OCT. Gas tamponade lasted approximately twice as long as might be expected compared with standard FTMH surgery. Objective visual acuity did not improve; however, perceived vision improved in all patients. CONCLUSIONS: Although FTMH in choroideremia is a rare finding, it could potentially mask central progression of the disease. Regular screening may help to diagnose holes at an earlier stage when the visual prognosis after surgery may be better. Standard macular hole surgery seems to be effective in gaining anatomic closure, which would be significant for patients who subsequently require macula detachment for subretinal gene therapy. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.