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Wood EH, Kreymerman A, Kowal T, Buickians D, Sun Y, Muscat S, Mercola M, Moshfeghi DM, Goldberg JL. Cellular and subcellular optogenetic approaches towards neuroprotection and vision restoration. Prog Retin Eye Res 2023; 96:101153. [PMID: 36503723 PMCID: PMC10247900 DOI: 10.1016/j.preteyeres.2022.101153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/27/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022]
Abstract
Optogenetics is defined as the combination of genetic and optical methods to induce or inhibit well-defined events in isolated cells, tissues, or animals. While optogenetics within ophthalmology has been primarily applied towards treating inherited retinal disease, there are a myriad of other applications that hold great promise for a variety of eye diseases including cellular regeneration, modulation of mitochondria and metabolism, regulation of intraocular pressure, and pain control. Supported by primary data from the authors' work with in vitro and in vivo applications, we introduce a novel approach to metabolic regulation, Opsins to Restore Cellular ATP (ORCA). We review the fundamental constructs for ophthalmic optogenetics, present current therapeutic approaches and clinical trials, and discuss the future of subcellular and signaling pathway applications for neuroprotection and vision restoration.
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Affiliation(s)
- Edward H Wood
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Alexander Kreymerman
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Tia Kowal
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - David Buickians
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Yang Sun
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Stephanie Muscat
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Mark Mercola
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Darius M Moshfeghi
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA.
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Chen Z, Chen B, Hu P, Liu H, Zheng D. A preliminary observation on rod cell photobiomodulation in treating diabetic macular edema. ADVANCES IN OPHTHALMOLOGY PRACTICE AND RESEARCH 2022; 2:100051. [PMID: 37846386 PMCID: PMC10577862 DOI: 10.1016/j.aopr.2022.100051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 03/25/2022] [Accepted: 04/21/2022] [Indexed: 10/18/2023]
Abstract
Purpose To evaluate the safety and effectiveness of photobiomodulation (PBM) in the treatment of diabetic macular edema (DME). Methods It was a single-center, self-controlled prospective study. The clinical records of 12 diabetic retinopathy patients (5 males and 7 females, 20 eyes in total) who were treated with PBM for DME at the Second Affiliated Hospital, Zhejiang University School of Medicine, were analyzed. The mean age was 56 (26-68) years. All the participants received PBM treatment during darkness at night in no less than 5 days per week and no less than 8 h per day. In the baseline check and follow-up checks (1, 2, 6, 10, and 12 months after the start of treatment), the best-corrected visual acuity, the thickness of the retina in the macula, and the changes of the fundus lesions were observed. Wilcoxon signed rank test was used to compare the results before and after treatment. P < 0.05 was considered statistically significant. Results No fundus complication was observed during follow-up checks. In baseline and 12-month follow-up checks, the best-corrected visual acuity was 71.75 ± 12.47 and 79.50 ± 10.85, maximal retinal thickness in macular area was 390.95 ± 77.12 μm and 354.13 ± 55.03 μm, average retinal thickness in macular area was 334.25 ± 36.45 μm and 314.31 ± 33.28 μm, foveal thickness was 287.00 ± 46.79 μm and 265.63 ± 67.14 μm. The best-corrected visual acuity, average retinal thickness in macular area in consecutive follow-up results except that in the 1st month showed significant difference compared with baseline results. There were significant difference between every follow-up result and baseline result of maximal retinal thickness in macular area (P < 0.05). All follow-up results of foveal thickness were not significantly different (P > 0.05) from the baseline result, except that in the 6th month (P = 0.049). Obvious improvement could be observed in retinal fundus fluorescein angiography images. Conclusions PBM is a safe and effective treatment of DME, which deserves further investigation.
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Affiliation(s)
- Zhiqing Chen
- Eye Centre, The Second Affiliated Hospital of the School of Medicine, Zhejiang University, Hangzhou, China
| | - Binbin Chen
- Eye Centre, The Second Affiliated Hospital of the School of Medicine, Zhejiang University, Hangzhou, China
| | - Peike Hu
- Eye Centre, The Second Affiliated Hospital of the School of Medicine, Zhejiang University, Hangzhou, China
| | - Haipeng Liu
- Research Centre for Intelligent Healthcare, University of Coventry, Coventry, UK
| | - Dingchang Zheng
- Research Centre for Intelligent Healthcare, University of Coventry, Coventry, UK
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Tonade D, Kern TS. Photoreceptor cells and RPE contribute to the development of diabetic retinopathy. Prog Retin Eye Res 2021; 83:100919. [PMID: 33188897 PMCID: PMC8113320 DOI: 10.1016/j.preteyeres.2020.100919] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 10/27/2020] [Accepted: 10/31/2020] [Indexed: 12/26/2022]
Abstract
Diabetic retinopathy (DR) is a leading cause of blindness. It has long been regarded as vascular disease, but work in the past years has shown abnormalities also in the neural retina. Unfortunately, research on the vascular and neural abnormalities have remained largely separate, instead of being integrated into a comprehensive view of DR that includes both the neural and vascular components. Recent evidence suggests that the most predominant neural cell in the retina (photoreceptors) and the adjacent retinal pigment epithelium (RPE) play an important role in the development of vascular lesions characteristic of DR. This review summarizes evidence that the outer retina is altered in diabetes, and that photoreceptors and RPE contribute to retinal vascular alterations in the early stages of the retinopathy. The possible molecular mechanisms by which cells of the outer retina might contribute to retinal vascular damage in diabetes also are discussed. Diabetes-induced alterations in the outer retina represent a novel therapeutic target to inhibit DR.
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Affiliation(s)
- Deoye Tonade
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA
| | - Timothy S Kern
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH, USA; Veterans Administration Medical Center Research Service, Cleveland, OH, USA; Gavin Herbert Eye Institute, University of California Irvine, Irvine, CA, USA; Veterans Administration Medical Center Research Service, Long Beach, CA, USA.
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Abstract
BACKGROUND Age-related macular degeneration (AMD) is one of the leading causes of blindness in high-income countries. The majority of cases of AMD are of the non-exudative type. Experts have proposed photobiomodulation (PBM) therapy as a non-invasive procedure to restore mitochondrial function, upregulate cytoprotective factors and prevent apoptotic cell death in retinal tissue affected by AMD. OBJECTIVES To assess the effectiveness and safety of PBM compared to standard care, no treatment or sham treatment for people with non-exudative AMD. SEARCH METHODS We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (Issue 5, 2020), Ovid MEDLINE, Embase, ISRCTN, ClinicalTrials.gov and the WHO ICTRP to 11 May 2020 with no language restrictions. SELECTION CRITERIA The review included randomised controlled trials (RCTs) on participants receiving any type of PBM therapy for non-exudative AMD compared to standard care, sham treatment or no treatment. DATA COLLECTION AND ANALYSIS We used standard methodological procedures expected by Cochrane. We considered the following outcome measures at 12 months: best-corrected visual acuity (BCVA) ; contrast sensitivity; near vision; low luminance density score; reading speed; vision-related quality of life score; and adverse events such as progression of AMD and conversion to exudative AMD. We graded the certainty of the evidence using GRADE. MAIN RESULTS We included two published RCTs from single centres in the UK and Canada, which recruited 60 participants (60 eyes) and 30 participants (46 eyes) respectively. Participants in these trials were people with non-exudative AMD with Age-Related Eye Disease Study (AREDS) categories 2 to 4. One study compared single wavelength PBM with no treatment. This study was at risk of performance bias because the study was not masked, and there was attrition bias. One study compared multi-wavelength PBM with sham treatment and conflicts of interest were reported by study investigators. We also identified three eligible ongoing RCTs from searching the clinical trials database. When comparing PBM with sham treatment or no treatment for non-exudative AMD, there was no evidence of any meaningful clinical difference in BCVA at 12 months (mean difference (MD) 0.02 logMAR, 95% confidence interval (CI) -0.02 to 0.05; 2 RCTs, 90 eyes; low-certainty evidence). One study comparing multi-wavelength PBM with sham treatment showed an improvement in contrast sensitivity at Level E (18 cycles/degree) at 12 months (MD 0.29 LogCS, 95% CI 0.23 to 0.35; 1 RCT, 46 eyes; low-certainty evidence). Visual function and health-related quality of life scores were comparable between single wavelength PBM and no treatment groups at 12 months (VFQ-48 score MD 0.43, 95% CI -0.17 to 1.03; P = 0.16; 1 RCT, 47 eyes; low-certainty evidence). When comparing PBM with sham treatment or no treatment for non-exudative AMD, there was no evidence of any meaningful clinical difference in conversion to exudative AMD (risk ratio (RR) 0.97, 95% CI 0.17 to 5.44; 2 RCTs, 96 eyes; very low-certainty evidence) at 12 months. There was inconclusive evidence that single wavelength PBM prevents the progression of AMD (RR 0.79, 95% CI 0.41 to 1.53; P = 0.48; 1 RCT, 50 eyes; low-certainty evidence). Disease progression was defined as the development of advanced AMD or significant increase in drusen volume. No included study reported near vision, low luminance vision or reading speed outcomes. AUTHORS' CONCLUSIONS Currently there remains uncertainty whether PBM treatment is beneficial in slowing progression of non-exudative macular degeneration. There is a need for further well-designed controlled trials assessing dosimetry, powered for both effectiveness and safety outcomes. Consideration should be given to the adoption of agreed clinical outcome measures and patient-based outcome measures for AMD.
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Affiliation(s)
- Christin Henein
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
- NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
| | - David Hw Steel
- Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
- Sunderland Eye Infirmary, Sunderland, UK
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Effects of emixustat hydrochloride in patients with proliferative diabetic retinopathy: a randomized, placebo-controlled phase 2 study. Graefes Arch Clin Exp Ophthalmol 2021; 259:369-378. [PMID: 32852613 PMCID: PMC7843479 DOI: 10.1007/s00417-020-04899-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/29/2020] [Accepted: 08/16/2020] [Indexed: 01/18/2023] Open
Abstract
PURPOSE To evaluate the effects of oral emixustat hydrochloride on pro-angiogenic and inflammatory cytokines in the aqueous humor, as well as other ophthalmic parameters, in subjects with proliferative diabetic retinopathy (PDR). METHODS Twenty-three patients with PDR, with or without diabetic macular edema (DME), were assigned to emixustat or placebo in daily oral doses ranging from 5 to 40 mg over a step-up titration period, for 84 days. The main outcome measures included levels of IL-1β, IL-6, IL-8, TGFβ-1, and VEGF in the aqueous humor. RESULTS Seven of 12 subjects (58%) who were randomized to emixustat and 11 of 12 subjects (92%) who were randomized to placebo completed the study. No statistically significant differences between treatment groups were observed for changes in any of the aqueous humor cytokines tested. However, median VEGF levels were slightly reduced in the emixustat but not the placebo group (- 70.0 pg/mL versus + 42.7 pg/mL, or - 11.8% versus + 6.7%). In a post hoc analysis of all subjects (with or without DME), statistically significant differences between treatment arms in mean changes from baseline in central subfield thickness (CST; emixustat - 11.9 μm, placebo + 36.2 μm; P = 0.076) and total macular volume (TMV; emixustat - 0.13 mm3, placebo + 0.23 mm3; P = 0.026) were observed, both favoring emixustat. Emixustat's safety profile was consistent with prior studies (i.e., the adverse events of delayed dark adaptation and visual impairment were more common in subjects treated with emixustat). CONCLUSION Although this pilot study did not demonstrate statistically significant differences in changes in aqueous humor cytokine levels between the emixustat and placebo groups, VEGF levels were slightly reduced in the emixustat but not in the placebo group. In addition, statistically significant differences favoring the emixustat group were observed in CST and TMV among all subjects. These data warrant further investigation of emixustat's potential therapeutic effects in diabetic retinopathy. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02753400 (April 2016).
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Abstract
Vision loss, among the most feared complications of diabetes, is primarily caused by diabetic retinopathy, a disease that manifests in well-recognized, characteristic microvascular lesions. The reasons for retinal susceptibility to damage in diabetes are unclear, especially considering that microvascular networks are found in all tissues. However, the unique metabolic demands of retinal neurons could account for their vulnerability in diabetes. Photoreceptors are the first neurons in the visual circuit and are also the most energy-demanding cells of the retina. Here, we review experimental and clinical evidence linking photoreceptors to the development of diabetic retinopathy. We then describe the influence of retinal illumination on photoreceptor metabolism, effects of light modulation on the severity of diabetic retinopathy, and recent clinical trials testing the treatment of diabetic retinopathy with interventions that impact photoreceptor metabolism. Finally, we introduce several possible mechanisms that could link photoreceptor responses to light and the development of retinal vascular disease in diabetes. Collectively, these concepts form the basis for a growing body of investigative efforts aimed at developing novel pharmacologic and nonpharmacologic tools that target photoreceptor physiology to treat a very common cause of blindness across the world.
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Rubinstein Y, Weiner C, Chetrit N, Newman H, Hecht I, Shoshany N, Pras E. Effect of light and diurnal variation on macular thickness in X-linked retinoschisis: a case series. Graefes Arch Clin Exp Ophthalmol 2020; 258:529-536. [PMID: 31897705 DOI: 10.1007/s00417-019-04578-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/07/2019] [Accepted: 12/18/2019] [Indexed: 10/25/2022] Open
Abstract
BACKGROUND Diurnal variations in foveal thickness have been reported in several ocular pathologies including X-linked retinoschisis (XLRS), but its underlying mechanism is poorly understood. Rods are active under scotopic conditions with high metabolic demand, and its decrease may have positive effect on metabolic activity and macular thickness. The purpose of this study is to evaluate whether exposure to light and diurnal variation influence macular thickness in XLRS patients. METHODS Five patients with clinical suspicion of XLRS underwent RS1 gene sequencing and optical coherence tomography measurements at three consecutive times: morning following sleep in a dark room, morning following sleep in an illuminated room, and late afternoon following sleep in an illuminated room. Central macular thickness (CMT) was compared between measurements, and molecular analysis was performed. RESULTS Five RS1 mutations were identified: p.Gly140Arg, p.Arg141Cys, p.Gly109Glu, p.Pro193Leu, and p.Arg200His in patients 1-5, respectively. Two patients (4-5) had atrophied macula and were excluded from macular thickness variation analysis. A significant decrease in CMT between morning and afternoon measurements was observed in all patients (1-3: mean: 455.0 ± 32 μm to 342.17 ± 39 μm, 25%). Morning measurements following sleep in an illuminated room show a CMT reduction in all eyes of all patients with a mean reduction of 113 μm (mean: 547.17 ± 105 μm to 455.0 ± 32 μm, 17%). CONCLUSIONS Among XLRS patients, CMT decreased at the afternoon compared to the morning of the same day and may be reduced following sleep in an illuminated room. These results help shed light on the pathophysiologic process underlying intraretinal fluid accumulation involved with the disease.
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Affiliation(s)
- Yair Rubinstein
- Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel.,Matlow's Ophthalmogenetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Chen Weiner
- Matlow's Ophthalmogenetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel.,Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Noa Chetrit
- Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Hadas Newman
- Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.,Department of Ophthalmology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Idan Hecht
- Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel. .,Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
| | - Nadav Shoshany
- Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel.,Matlow's Ophthalmogenetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel
| | - Eran Pras
- Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel.,Matlow's Ophthalmogenetic Laboratory, Department of Ophthalmology, Shamir Medical Center (formerly Assaf Harofeh Medical Center), Zerifin, Israel.,Sackler faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Abstract
PURPOSE OF REVIEW To introduce recent advances in the understanding of diabetic retinopathy and to summarize current and emerging strategies to treat this common and complex cause of vision loss. RECENT FINDINGS Advances in retinal imaging and functional analysis indicate that retinal vascular and neural pathologies exist long before the development of clinically visible retinopathy. Such diagnostics could facilitate risk stratification and selective early intervention in high-risk patients. Antagonists of the vascular endothelial growth factor pathway effectively reduce vision loss in diabetes and promote regression of disease severity. Promising new strategies to treat diabetic retinopathy involve novel systemic diabetes therapy and ocular therapies that antagonize angiogenic growth factor signaling, improve blood-retina barrier function and neurovascular coupling, modulate neuroretinal metabolism, or provide neuroprotection. Long considered a pure microvasculopathy, diabetic retinopathy in fact affects the neural and vascular retina as well as neurovascular communication. Emerging therapies include those that target neuroretinal dysfunction in addition to those modulating vascular biology.
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Affiliation(s)
- Avinash Honasoge
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave. 8096, St. Louis, MO, 63108, USA
| | - Eric Nudleman
- Shiley Eye Institute, University of California, San Diego, La Jolla, CA, USA
| | - Morton Smith
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave. 8096, St. Louis, MO, 63108, USA
| | - Rithwick Rajagopal
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 S. Euclid Ave. 8096, St. Louis, MO, 63108, USA.
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Hsiao CC, Hsu HM, Yang CM, Yang CH. Correlation of retinal vascular perfusion density with dark adaptation in diabetic retinopathy. Graefes Arch Clin Exp Ophthalmol 2019; 257:1401-1410. [PMID: 31001668 DOI: 10.1007/s00417-019-04321-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 03/20/2019] [Accepted: 04/06/2019] [Indexed: 11/30/2022] Open
Abstract
PURPOSE To evaluate the anatomic versus functional changes in diabetic retinopathy (DR) by studying the correlation of retinal vascular perfusion density and dark adaptation (DA). METHODS Optical coherence tomography angiography (OCTA) and DA tests were performed in diabetic patients and nondiabetic controls. DA was measured using AdaptDx dark adaptometer and the rod intercept was recorded. Macular OCTA images were acquired using the RTVue XR Avanti with AngioVue. RESULTS Eighty-six eyes from 57 patients with diabetes (19 with no DR, 19 with non-proliferative DR [NPDR], and 19 with proliferative DR [PDR] who had undergone photocoagulation) and 10 eyes from 10 patients without diabetes were recruited. A significant decrease in vascular density and a prolonged rod intercept were found as DR progressed (P < .01). A negative trend was found between vascular density and the rod intercept. The negative trend in the deep layer (R2 = 0.28) was more substantial than that in the superficial layer (R2 = 0.14). A prolonged rod intercept was associated with elevated HbA1c (R2 = 0.08). CONCLUSIONS The vascular density of the macula could be assessed by OCTA and the functional change in the outer retina could be measured non-invasively by DA. The severity of decreasing vascular density and prolongation of DA are proportional to progression of DR. Decreased deep retinal vascular perfusion density and impaired DA response are correlated and show a negative trend according to the severity of DR.
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Affiliation(s)
- Chia-Chieh Hsiao
- Department of Ophthalmology, National Taiwan University Hospital, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan
| | - Hsueh-Min Hsu
- Department of Ophthalmology, National Taiwan University College of Medicine, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan
| | - Chung-May Yang
- Department of Ophthalmology, National Taiwan University Hospital, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan.,Department of Ophthalmology, National Taiwan University College of Medicine, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan
| | - Chang-Hao Yang
- Department of Ophthalmology, National Taiwan University Hospital, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan. .,Department of Ophthalmology, National Taiwan University College of Medicine, No. 7, Chun-Shan S. Rd., Taipei City, 100, Taiwan.
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Liu H, Tang J, Du Y, Saadane A, Samuels I, Veenstra A, Kiser JZ, Palczewski K, Kern TS. Transducin1, Phototransduction and the Development of Early Diabetic Retinopathy. Invest Ophthalmol Vis Sci 2019; 60:1538-1546. [PMID: 30994864 PMCID: PMC6736377 DOI: 10.1167/iovs.18-26433] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 03/14/2019] [Indexed: 12/31/2022] Open
Abstract
Purpose Recent evidence suggests that retinal photoreceptor cells have an important role in the pathogenesis of retinal microvascular lesions in diabetes. We investigated the role of rod cell phototransduction on the pathogenesis of early diabetic retinopathy (DR) using Gnat1-/- mice (which causes permanent inhibition of phototransduction in rod cells without degeneration). Methods Retinal thickness, oxidative stress, expression of inflammatory proteins, electroretinograms (ERG) and optokinetic responses, and capillary permeability and degeneration were evaluated at up to 8 months of diabetes. Results The diabetes-induced degeneration of retinal capillaries was significantly inhibited in the Gnat1-/- diabetics. The effect of the Gnat1 deletion on the diabetes-induced increase in permeability showed a nonuniform accumulation of albumin in the neural retina; the defect was inhibited in diabetic Gnat1-/- mice in the inner plexiform layer (IPL), but neither in the outer plexiform (OPL) nor inner nuclear (INL) layers. In Gnat1-deficient animals, the diabetes-induced increase in expression of inflammatory associated proteins (iNOS and ICAM-1, and phosphorylation of IĸB) in the retina, and the leukocyte mediated killing of retinal endothelial cells were inhibited, however the diabetes-mediated induction of oxidative stress was not inhibited. Conclusions In conclusion, deletion of transducin1 (and the resulting inhibition of phototransduction in rod cells) inhibits the development of retinal vascular pathology in early DR.
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Affiliation(s)
- Haitao Liu
- Department of Biology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jie Tang
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Yunpeng Du
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Aicha Saadane
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Ivy Samuels
- Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, United States
- Department of Ophthalmic Research, Cleveland Clinic, Cleveland, Ohio, United States
| | - Alex Veenstra
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Jianying Z. Kiser
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
- Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, United States
| | - Timothy S. Kern
- Department of Pharmacology, Case Western Reserve University, Cleveland, Ohio, United States
- Veterans Administration Medical Center Research Service 151, Cleveland, Ohio, United States
- Gavin Herbert Eye Institute, University of California Irvine, Irvine, California, United States
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Okada M, Chhablani J. Out of darkness comes light-is there a role for light masks in treatment of diabetic macular oedema? ANNALS OF TRANSLATIONAL MEDICINE 2018; 6:S73. [PMID: 30613648 DOI: 10.21037/atm.2018.10.50] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Mali Okada
- Department of Ophthalmology, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Jay Chhablani
- Smt Kanuri Santhamma Center for Vitreoretinal Diseases, LV Prasad Eye Institute, Hyderabad, India
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Retinal Vessel Diameter Changes in Relation to Dark Adaptation and Acute Hyperglycemia. J Ophthalmol 2018; 2018:7064359. [PMID: 30319819 PMCID: PMC6167562 DOI: 10.1155/2018/7064359] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 08/16/2018] [Indexed: 11/17/2022] Open
Abstract
The purpose of this experimental clinical study was to assess the effects of dark adaptation and acute changes in glycemia on retinal vessel diameters in men. The study included 14 patients (mean age 63 years, range 48–74 years) with type 2 diabetes mellitus and minimal or no diabetic retinopathy. Retinal vessel diameters were assessed using infrared photography before and after dark adaptation, first while fasting and then at peak hyperglycemia during an oral glucose tolerance test (OGTT). Dark adaptation was accompanied by retinal vasodilatation, both during fasting (mean glycemia 7.6 ± 1.7 mM) and postprandial hyperglycemia (15.7 ± 4.2 mM). When fasting, the increase in vein diameter during dark adaptation was 2.0% after 20 min (P=0.018) and 2.9% after 40 min (P=0.010). When subjects were hyperglycemic, the increase during dark adaptation was 2.8% for retinal vein diameters (P=0.027) and 2.0% for retinal artery diameters after 20 min (P=0.002) and 1.7% for retinal artery diameters after 40 min (P=0.022). For identical conditions of light/dark adaptation, retinal vessels were dilated when subjects were fasting compared to postprandial hyperglycemia. Thus, darkness and fasting were both associated with retinal vasodilation in this short-term experiment in patients with type 2 diabetes. Future studies should determine whether both the stimuli of vasodilation lead to retinal hyperperfusion, which would support that they may be involved in the aggravation of diabetic retinopathy.
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Robinson DG, Margrain TH, Dunn MJ, Bailey C, Binns AM. Low-Level Nighttime Light Therapy for Age-Related Macular Degeneration: A Randomized Clinical Trial. ACTA ACUST UNITED AC 2018; 59:4531-4541. [DOI: 10.1167/iovs.18-24284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- D. Grant Robinson
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Tom H. Margrain
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Matt J. Dunn
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Clare Bailey
- Bristol Eye Hospital, Lower Maudlin Street, Bristol, United Kingdom
| | - Alison M. Binns
- Division of Optometry and Visual Science, School of Health Sciences, City, University of London, United Kingdom
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14
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Wong TY. Are light masks useful for early diabetic macular oedema? Lancet Diabetes Endocrinol 2018. [PMID: 29519745 DOI: 10.1016/s2213-8587(18)30068-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Tien Yin Wong
- Singapore Eye Research Institute, Singapore National Eye Centre, 168751 Singapore; Duke-NUS Medical School, National University of Singapore, Singapore.
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15
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Sivaprasad S, Vasconcelos JC, Prevost AT, Holmes H, Hykin P, George S, Murphy C, Kelly J, Arden GB. Clinical efficacy and safety of a light mask for prevention of dark adaptation in treating and preventing progression of early diabetic macular oedema at 24 months (CLEOPATRA): a multicentre, phase 3, randomised controlled trial. Lancet Diabetes Endocrinol 2018; 6. [PMID: 29519744 PMCID: PMC5908782 DOI: 10.1016/s2213-8587(18)30036-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND We aimed to assess 24-month outcomes of wearing an organic light-emitting sleep mask as an intervention to treat and prevent progression of non-central diabetic macular oedema. METHODS CLEOPATRA was a phase 3, single-blind, parallel-group, randomised controlled trial undertaken at 15 ophthalmic centres in the UK. Adults with non-centre-involving diabetic macular oedema were randomly assigned (1:1) to wearing either a light mask during sleep (Noctura 400 Sleep Mask, PolyPhotonix Medical, Sedgefield, UK) or a sham (non-light) mask, for 24 months. Randomisation was by minimisation generated by a central web-based computer system. Outcome assessors were masked technicians and optometrists. The primary outcome was the change in maximum retinal thickness on optical coherence tomography (OCT) at 24 months, analysed using a linear mixed-effects model incorporating 4-monthly measurements and baseline adjustment. Analysis was done using the intention-to-treat principle in all randomised patients with OCT data. Safety was assessed in all patients. This trial is registered with Controlled-Trials.com, number ISRCTN85596558. FINDINGS Between April 10, 2014, and June 15, 2015, 308 patients were randomly assigned to wearing the light mask (n=155) or a sham mask (n=153). 277 patients (144 assigned the light mask and 133 the sham mask) contributed to the mixed-effects model over time, including 246 patients with OCT data at 24 months. The change in maximum retinal thickness at 24 months did not differ between treatment groups (mean change -9·2 μm [SE 2·5] for the light mask vs -12·9 μm [SE 2·9] for the sham mask; adjusted mean difference -0·65 μm, 95% CI -6·90 to 5·59; p=0·84). Median compliance with wearing the light mask at 24 months was 19·5% (IQR 1·9-51·6). No serious adverse events were related to either mask. The most frequent adverse events related to the assigned treatment were discomfort on the eyes (14 with the light mask vs seven with the sham mask), painful, sticky, or watery eyes (14 vs six), and sleep disturbance (seven vs one). INTERPRETATION The light mask as used in this study did not confer long-term therapeutic benefit on non-centre-involving diabetic macular oedema and the study does not support its use for this indication. FUNDING The Efficacy and Mechanism Evaluation Programme, a Medical Research Council and National Institute for Health Research partnership.
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Affiliation(s)
- Sobha Sivaprasad
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK.
| | - Joana C Vasconcelos
- Imperial Clinical Trials Unit, School of Public Health, Imperial College London, London, UK
| | - A Toby Prevost
- Imperial Clinical Trials Unit, School of Public Health, Imperial College London, London, UK
| | - Helen Holmes
- King's Clinical Trials Unit at King's Health Partners, King's College London, London, UK
| | - Philip Hykin
- National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
| | - Sheena George
- Hillingdon Hospital, Hillingdon Hospitals National Health Service Foundation Trust, Uxbridge, UK
| | - Caroline Murphy
- King's Clinical Trials Unit at King's Health Partners, King's College London, London, UK
| | - Joanna Kelly
- King's Clinical Trials Unit at King's Health Partners, King's College London, London, UK
| | - Geoffrey B Arden
- Institute of Ophthalmology and Moorfields Eye Hospital, London, UK
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16
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Loss of CD40 attenuates experimental diabetes-induced retinal inflammation but does not protect mice from electroretinogram defects. Vis Neurosci 2018; 34:E009. [PMID: 28965505 DOI: 10.1017/s0952523817000074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Chronic low grade inflammation is considered to contribute to the development of experimental diabetic retinopathy (DR). We recently demonstrated that lack of CD40 in mice ameliorates the upregulation of inflammatory molecules in the diabetic retina and prevented capillary degeneration, a hallmark of experimental diabetic retinopathy. Herein, we investigated the contribution of CD40 to diabetes-induced reductions in retinal function via the electroretinogram (ERG) to determine if inflammation plays a role in the development of ERG defects associated with diabetes. We demonstrate that diabetic CD40-/- mice are not protected from reduction to the ERG b-wave despite failing to upregulate inflammatory molecules in the retina. Our data therefore supports the hypothesis that retinal dysfunction found in diabetics occurs independent of the induction of inflammatory processes.
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17
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Do photoreceptor cells cause the development of retinal vascular disease? Vision Res 2017; 139:65-71. [PMID: 28438678 DOI: 10.1016/j.visres.2017.03.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/29/2017] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
Abstract
The retinal vasculature is affected in a number of clinically important retinopathies, including diabetic retinopathy. There has been a considerable amount of research into the pathogenesis of retinal microvascular diseases, but the potential contribution of the most abundant cell population in the retina, photoreceptor cells, has been largely overlooked. This review summarizes ongoing research suggesting that photoreceptor cells play a critical role in the development of retinal vascular disease in diabetic retinopathy and other retinopathies.
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18
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Linsenmeier RA, Zhang HF. Retinal oxygen: from animals to humans. Prog Retin Eye Res 2017; 58:115-151. [PMID: 28109737 DOI: 10.1016/j.preteyeres.2017.01.003] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 10/20/2022]
Abstract
This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.
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Affiliation(s)
- Robert A Linsenmeier
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Neurobiology Department, Northwestern University, 2205 Tech Drive, Evanston 60208-3520, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
| | - Hao F Zhang
- Biomedical Engineering Department, Northwestern University, 2145 Sheridan Road, Evanston 60208-3107, IL, USA; Ophthalmology Department, Northwestern University, 645 N. Michigan Ave, Suite 440, Chicago 60611, IL, USA.
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19
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Sahni JN, Czanner G, Gutu T, Taylor SA, Bennett KM, Wuerger SM, Grierson I, Murray-Dunning C, Holland MN, Harding SP. Safety and acceptability of an organic light-emitting diode sleep mask as a potential therapy for retinal disease. Eye (Lond) 2016; 31:97-106. [PMID: 27983728 DOI: 10.1038/eye.2016.259] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 09/13/2016] [Indexed: 11/09/2022] Open
Abstract
PurposeThe purpose of the study was to study the effect of an organic light-emitting diode sleep mask on daytime alertness, wellbeing, and retinal structure/function in healthy volunteers and in diabetic macular oedema (DMO).Patients and methodsHealthy volunteers in two groups, 18-30 yrs (A), 50-70 yrs (B) and people with DMO (C) wore masks (504 nm wavelength; 80 cd/m2 luminance; ≤8 h) nightly for 3 months followed by a 1-month recovery period. Changes from baseline were measured for (means): psychomotor vigilance task (PVT) (number of lapses (NL), response time (RT)), sleep, depression, psychological wellbeing (PW), visual acuity, contrast sensitivity, colour, electrophysiology, microperimetry, and retinal thickness on OCT.ResultsOf 60 participants, 16 (27%) withdrew, 8 (13%) before month 1, due to sleep disturbances and mask intolerance. About 36/55 (65%) who continued beyond month 1 reported ≥1 adverse event. At month 3 mean PVT worsened in Group A (RT (7.65%, P<0.001), NL (43.3%, P=0.005)) and mean PW worsened in all groups (A 28.0%, P=0.01, B 21.2%, P=0.03, C 12.8%, P<0.05). No other clinically significant safety signal was detected. Cysts reduced/resolved in the OCT subfield of maximal pathology in 67% Group C eyes. Thinning was greater at 3 and 4 months for greater baseline thickness (central subfield P<0.001, maximal P<0.05).ConclusionSleep masks showed no major safety signal apart from a small impairment of daytime alertness and a moderate effect on wellbeing. Masks were acceptable apart from in some healthy participants. Preliminary data suggest a beneficial effect on retinal thickness in DMO. This novel therapeutic approach is ready for large clinical trials.
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Affiliation(s)
- J N Sahni
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK.,Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - G Czanner
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK.,Department of Biostatistics, Institute of Translational Medicine, University of Liverpool, Liverpool, UK
| | - T Gutu
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK
| | - S A Taylor
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK
| | - K M Bennett
- Department of Psychological Sciences, Institute of Psychology, Health and Society, Liverpool, UK
| | - S M Wuerger
- Department of Psychological Sciences, Institute of Psychology, Health and Society, Liverpool, UK
| | - I Grierson
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | - C Murray-Dunning
- Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
| | | | - S P Harding
- St Paul's Eye Unit, Royal Liverpool University Hospitals NHS Trust, Liverpool, UK.,Department of Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
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20
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Roy S, Kern TS, Song B, Stuebe C. Mechanistic Insights into Pathological Changes in the Diabetic Retina: Implications for Targeting Diabetic Retinopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 187:9-19. [PMID: 27846381 DOI: 10.1016/j.ajpath.2016.08.022] [Citation(s) in RCA: 145] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 07/27/2016] [Accepted: 08/04/2016] [Indexed: 12/16/2022]
Abstract
Increasing evidence points to inflammation as one of the key players in diabetes-mediating adverse effects to the neuronal and vascular components of the retina. Sustained inflammation induces biochemical and molecular changes, ultimately contributing to retinal complications and vision loss in diabetic retinopathy. In this review, we describe changes involving metabolic abnormalities secondary to hyperglycemia, oxidative stress, and activation of transcription factors, together with neuroglial alterations in the diabetic retina. Changes in biochemical pathways and how they promote pathophysiologic developments involving proinflammatory cytokines, chemokines, and adhesion molecules are discussed. Inflammation-mediated leukostasis, retinal ischemia, and neovascularization and their contribution to pathological and clinical stages leading to vision loss in diabetic retinopathy (DR) are highlighted. In addition, potential treatment strategies involving fibrates, connexins, neuroprotectants, photobiomodulation, and anti-inflammatory agents against the development and progression of DR lesions are reviewed. The importance of appropriate animal models for testing novel strategies against DR lesions is discussed; in particular, a novel nonhuman primate model of DR and the suitability of rodent models are weighed. The purpose of this review is to highlight our current understanding of the pathogenesis of DR and to summarize recent advances using novel approaches or targets to investigate and inhibit the retinopathy.
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Affiliation(s)
- Sayon Roy
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts.
| | - Timothy S Kern
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio; Department of Clinical and Molecular Endocrinology, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - Brian Song
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts
| | - Caren Stuebe
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts; Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts
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21
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Light adaptation does not prevent early retinal abnormalities in diabetic rats. Sci Rep 2016; 6:21075. [PMID: 26852722 PMCID: PMC4745072 DOI: 10.1038/srep21075] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Accepted: 01/18/2016] [Indexed: 11/23/2022] Open
Abstract
The aetiology of diabetic retinopathy (DR), the leading cause of blindness in the developed world, remains controversial. One hypothesis holds that retinal hypoxia, exacerbated by the high O2 consumption of rod photoreceptors in the dark, is a primary cause of DR. Based on this prediction we investigated whether early retinal abnormalities in streptozotocin-induced diabetic rats are alleviated by preventing the rods from dark adapting. Diabetic rats and their non-diabetic littermates were housed in a 12:12 hour light-dim light photocycle (30 lux during the day and 3 lux at night). Progression of early retinal abnormalities in diabetic rats was assessed by monitoring the ERG b-wave and oscillatory potentials, Müller cell reactive gliosis, and neuronal cell death, as assayed by TUNEL staining and retinal thickness at 6 and 12 weeks after diabetes induction. Maintaining diabetic animals in a dim-adapting light did not slow the progression of these neuronal and glial changes when compared to diabetic rats maintained in a standard 12:12 hour light-dark photocycle (30 lux during the day and 0 lux at night). Our results indicate that neuronal and glial abnormalities in early stages of diabetes are not exacerbated by rod photoreceptor O2 consumption in the dark.
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22
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Sivaprasad S, Arden G. Spare the rods and spoil the retina: revisited. Eye (Lond) 2016; 30:189-92. [PMID: 26656085 PMCID: PMC4763134 DOI: 10.1038/eye.2015.254] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 11/10/2015] [Indexed: 01/23/2023] Open
Abstract
Visual function improves with oxygen inhalation in people with diabetes even in the absence of visible retinopathy. Rods consume the most oxygen in the retina due to the high metabolic activity required to maintain the dark current. Therefore, Arden hypothesized that in diabetes where oxygen supply may also be affected due to the changes in retinal vasculature, prevention of dark adaptation may be a viable option to prevent or decrease the rate of progression of diabetic retinopathy. Animal experiments have proven that the absence of rods decreases the development of retinal neovascularisation. The same principle applies to panretinal photocoagulation, an established treatment for proliferative diabetic retinopathy. Recently, a few clinical studies have also shown that preventing dark adaptation by suppressing rods with 500-nm light source at night decreases the rate of progression of early diabetic retinopathy and maculopathy in the short-term. We await the results of a large two-year multi-centre trial (CLEOPATRA trial) to evaluate the long-term effects of decreasing dark adaptation by applying a 500nm light source as a mask over eyes with non-central diabetic macular oedema.
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Affiliation(s)
- S Sivaprasad
- NIHR Moorfields Biomedical Research Centre, London, UK
| | - G Arden
- NIHR Moorfields Biomedical Research Centre, London, UK
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23
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Abstract
In diabetes, retinal blood flow is compromised, and retinal hypoxia is likely to be further intensified during periods of darkness. During dark adaptation, rod photoreceptors in the outer retina are maximally depolarized and continuously release large amounts of the neurotransmitter glutamate-an energetically demanding process that requires the highest oxygen consumption per unit volume of any tissue of the body. In complete darkness, even more oxygen is consumed by the outer retina, producing a steep fall in the retinal oxygen tension curve which reaches a nadir at the depth of the mitochondrial-rich rod inner segments. In contrast to the normal retina, the diabetic retina cannot meet the added metabolic load imposed by the dark-adapted rod photoreceptors; this exacerbates retinal hypoxia and stimulates the overproduction of vascular endothelial growth factor (VEGF). The use of nocturnal illumination to prevent dark adaptation, specifically reducing the rod photoreceptor dark current, should ameliorate diabetic retinopathy.
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Affiliation(s)
- David J Ramsey
- Department of Ophthalmology, Lahey Hospital & Medical Center, Tufts University School of Medicine, 41 Mall Road, Burlington, MA, 01805, USA.
| | - G B Arden
- University College London, London, UK.
- Moorfields Eye Hospital NHS Foundation Trust, London, UK.
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24
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Lin MK, Kim SH, Zhang L, Tsai YT, Tsang SH. Rod metabolic demand drives progression in retinopathies. Taiwan J Ophthalmol 2015; 5:105-108. [PMID: 29018679 PMCID: PMC5602704 DOI: 10.1016/j.tjo.2015.06.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 06/30/2015] [Indexed: 12/21/2022] Open
Abstract
Various factors are thought to cause the development and progression of disease in macular degeneration, diabetic retinopathy, and retinitis pigmentosa. Some of the deleterious processes include oxidative stress, hypoxia, metabolic derangement, genetics, and vasculopathy. In this review, we present a unified theory for the pathophysiology of several retinopathies based on the unique and intense metabolism of rod photoreceptors.
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Affiliation(s)
- Michael K Lin
- College of Physicians & Surgeons, Columbia University, New York, NY, USA
| | - Soo Hyun Kim
- Columbia College, Columbia University, New York, NY, USA
| | - Lijuan Zhang
- Bernard & Shirlee Brown Glaucoma Laboratory and Barbara & Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Yi-Ting Tsai
- Bernard & Shirlee Brown Glaucoma Laboratory and Barbara & Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Stephen H Tsang
- Bernard & Shirlee Brown Glaucoma Laboratory and Barbara & Donald Jonas Stem Cell Laboratory, Department of Ophthalmology, Columbia University, New York, NY, USA.,Department of Pathology and Cell Biology and Institute of Human Nutrition, Columbia University, New York, NY, USA
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25
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Sivaprasad S, Arden G, Prevost AT, Crosby-Nwaobi R, Holmes H, Kelly J, Murphy C, Rubin G, Vasconcelos J, Hykin P. A multicentre phase III randomised controlled single-masked clinical trial evaluating the clinical efficacy and safety of light-masks at preventing dark-adaptation in the treatment of early diabetic macular oedema (CLEOPATRA): study protocol for a randomised controlled trial. Trials 2014; 15:458. [PMID: 25417120 PMCID: PMC4255925 DOI: 10.1186/1745-6215-15-458] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Accepted: 11/05/2014] [Indexed: 11/30/2022] Open
Abstract
Background This study will evaluate hypoxia, as a novel concept in the pathogenesis of diabetic macular oedema (DMO). As the oxygen demand of the eye is maximum during dark-adaptation, we hypothesize that wearing light-masks during sleep will cause regression and prevent the development and progression of DMO. The study protocol comprises both an efficacy and mechanistic evaluation to test this hypothesis. Method/Design This is a phase III randomised controlled single-masked multicentre clinical trial to test the clinical efficacy of light-masks at preventing dark-adaptation in the treatment of non-central DMO. Three hundred patients with non-centre-involving DMO in at least one eye will be randomised 1:1 to light-masks and control masks (with no light) to be used during sleep at night for a period of 24 months. The primary outcome is regression of non-central oedema by assessing change in the zone of maximal retinal thickness at baseline on optical coherence tomography (SD-OCT). Secondary outcomes will evaluate the prevention of development and progression of DMO by assessing changes in retinal thickness in different regions of the macula, macular volume, refracted visual acuity and level of retinopathy. Safety parameters will include sleep disturbance. Adverse events and measures of compliance will be assessed over 24 months. Participants recruited to the mechanistic sub-study will have additional retinal oximetry, multifocal electroretinography (ERG) and microperimetry to evaluate the role of hypoxia by assessing and comparing changes induced by supplemental oxygen and the light-masks at 12 months. Discussion The outcomes of this study will provide insight into the pathogenesis of DMO and provide evidence on whether a simple, non-invasive device in the form of a light-mask can help prevent the progression to centre-involving DMO and visual impairment in people with diabetes.
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Affiliation(s)
- Sobha Sivaprasad
- NIHR Moorfields Biomedical Research Centre, 162, City Road, London EC1V 2PD, England.
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26
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McKeague C, Margrain TH, Bailey C, Binns AM. Low-level night-time light therapy for age-related macular degeneration (ALight): study protocol for a randomized controlled trial. Trials 2014; 15:246. [PMID: 24965385 PMCID: PMC4227140 DOI: 10.1186/1745-6215-15-246] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2013] [Accepted: 05/23/2014] [Indexed: 12/11/2022] Open
Abstract
Background Age-related macular degeneration (AMD) is the leading cause of blindness among older adults in the developed world. The only treatments currently available, such as ranibizumab injections, are for neovascular AMD, which accounts for only 10 to 15% of people with the condition. Hypoxia has been implicated as one of the primary causes of AMD, and is most acute at night when the retina is most metabolically active. By increasing light levels at night, the metabolic requirements of the retina and hence the hypoxia will be considerably reduced. This trial seeks to determine whether wearing a light mask that emits a dim, green light during the night can prevent the progression of early AMD. Methods/design ALight is a Phase I/IIa, multicentre, randomized controlled trial. Sixty participants (55 to 88 years old) with early AMD in one eye and neovascular AMD (nAMD) in the fellow eye will be recruited from nAMD clinics. They will be randomized (in the ratio 1:1), either to receive the intervention or to be in the untreated control group, stratified according to risk of disease progression. An additional 40 participants with healthy retinal appearance, or early AMD only, will be recruited for a baseline cross-sectional analysis. The intervention is an eye mask that emits a dim green light to illuminate the retina through closed eyelids at night. This is designed to reduce the metabolic activity of the retina, thereby reducing the potential risk of hypoxia. Participants will wear the mask every night for 12 months. Ophthalmologists carrying out monthly assessments will be masked to the treatment group, but participants will be aware of their treatment group. The primary outcome measure is the proportion of people who show disease progression during the trial period in the eye with early AMD. A co-primary outcome measure is the rate of retinal adaptation. As this is a trial of a CE-marked device for an off-label indication, a further main aim of this trial is to assess safety of the mask in the cohort of participants with AMD. Trial registration International Standard Randomised Controlled Trials Register: ISRCTN82148651
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Affiliation(s)
| | | | | | - Alison M Binns
- School of Optometry and Vision Sciences, Cardiff University, Cardiff CF24 4 LU, UK.
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27
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Abstract
For years, diabetic retinopathy has been defined based on vascular lesions, and neural abnormalities were not regarded as important. This review summarizes evidence that the neural retina has important effects on the retinal vasculature under normal conditions, and the interaction between the retinal neuroglial cells and vascular function is altered in diabetes. Importantly, new evidence raises a possibility that abnormalities within retinal neuroglial cells (notably photoreceptors) might actually be causing or initiating the vascular disease in diabetic retinopathy.
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Affiliation(s)
- Timothy S. Kern
- Department of Medicine, Case Western Reserve University Medicine, Cleveland, OH, USA
- Department of Medicine, Louis Stokes Cleveland Veterans Administration Medical Center, Cleveland, OH, USA
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28
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Barbur JL, Connolly DM. Effects of hypoxia on color vision with emphasis on the mesopic range. EXPERT REVIEW OF OPHTHALMOLOGY 2014. [DOI: 10.1586/eop.11.32] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Photoreceptor cells are major contributors to diabetes-induced oxidative stress and local inflammation in the retina. Proc Natl Acad Sci U S A 2013; 110:16586-91. [PMID: 24067647 DOI: 10.1073/pnas.1314575110] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Accumulating evidence suggests that photoreceptor cells play a previously unappreciated role in the development of early stages of diabetic retinopathy, but the mechanism by which this occurs is not clear. Inhibition of oxidative stress is known to inhibit the vascular lesions of early diabetic retinopathy, and we investigated whether the diabetes-induced oxidative stress in the retina emanates from photoreceptors. Superoxide generation was assessed in retinas of male C57BL/6J mice made diabetic for 2 mo (4 mo of age when killed) using histochemical (dichlorofluorescein and dihydroethidine) and bioluminescence (lucigenin) methods. Photoreceptors were eliminated in vivo by genetic (opsin(-/-)) and chemical (iodoacetic acid) techniques. Immunoblots were used to measure expression of intercellular adhesion molecule 1 and the inducible form of nitric oxide synthase. Diabetes increased the generation of superoxide by diabetic mouse retina more at night than during the day. Photoreceptors were the major source of reactive oxygen species in the retina, and their deletion (either genetically in opsin(-/-) mice or acutely with iodoacetic acid) inhibited the expected diabetes-induced increase in superoxide and inflammatory proteins in the remaining retina. Both mitochondria and NADPH oxidase contributed to the observed retinal superoxide generation, which could be inhibited in vivo with either methylene blue or apocynin. Photoreceptors are the major source of superoxide generated by retinas of diabetic mice. Pharmaceuticals targeting photoreceptor oxidative stress could offer a unique therapy for diabetic retinopathy.
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30
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Arden GB, Sivaprasad S. The pathogenesis of early retinal changes of diabetic retinopathy. Doc Ophthalmol 2012; 124:15-26. [PMID: 22302291 DOI: 10.1007/s10633-011-9305-y] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Accepted: 12/14/2011] [Indexed: 01/04/2023]
Abstract
Recent successful trials of antibodies to vascular endothelial growth factor (VEGF) in diabetic retinopathy implicate this cytokine as a major cause of diabetic retinopathy (DR) and diabetic macular oedema (DME). The mechanisms which cause VEGF to be over-expressed to cause the vasculopathy are not entirely clear. This review explores the earliest changes to the retina in DR and the factors that predispose or prevent DR, including sleep apnoea, receptor degenerations laser treatment and VEGF polymorphism. The review also presents the evidence that retinal hypoxia, existing in the earliest stages, causes DR. This hypoxia is much increased by dark adaptation, indicating a new and possibly superior therapy.
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Lung JCY, Swann PG, Chan HHL. Early local functional changes in the human diabetic retina: a global flash multifocal electroretinogram study. Graefes Arch Clin Exp Ophthalmol 2012; 250:1745-54. [PMID: 22527315 DOI: 10.1007/s00417-012-2010-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/15/2012] [Accepted: 03/19/2012] [Indexed: 01/04/2023] Open
Abstract
PURPOSE To investigate early functional changes of local retinal defects in type II diabetic patients using the global flash multifocal electroretinogram (MOFO mfERG). METHODS Thirty-eight diabetic patients and 14 age-matched controls were recruited. Nine of the diabetics were free from diabetic retinopathy (DR), while the remainder had mild to moderate non-proliferative diabetic retinopathy. The MOFO mfERG was performed at high (98 %) and low (46 %) contrast levels. MfERG responses were grouped into 35 regions for comparison with DR classification at those locations. Z-scores of the regional mfERG responses were compared across different types of DR defects. RESULTS The mfERG waveform consisted of the direct component (DC) and the induced component (IC). Local reduction in DC and IC amplitudes were found in diabetic patients with and without DR. With increasing severity of retinopathy, there was a further deterioration in amplitude of both components. Under MOFO mfERG paradigm, amplitude was a useful screening parameter. CONCLUSION The MOFO mfERG can help in detecting early functional anomalies before the appearance of visible signs, and may assist in monitoring further functional deterioration in diabetic patients.
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Affiliation(s)
- Jenny C Y Lung
- Laboratory of Experimental Optometry (Neuroscience), School of Optometry, The Hong Kong Polytechnic University, Hong Kong SAR, China
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Crosby-Nwaobi R, Heng LZ, Sivaprasad S. Retinal Vascular Calibre, Geometry and Progression of Diabetic Retinopathy in Type 2 Diabetes Mellitus. Ophthalmologica 2012; 228:84-92. [DOI: 10.1159/000337252] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 02/02/2012] [Indexed: 11/19/2022]
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Lange CA, Bainbridge JW. Oxygen Sensing in Retinal Health and Disease. Ophthalmologica 2012; 227:115-31. [DOI: 10.1159/000331418] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 07/29/2011] [Indexed: 12/24/2022]
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Arden GB, Jyothi S, Hogg CH, Lee YF, Sivaprasad S. Regression of early diabetic macular oedema is associated with prevention of dark adaptation. Eye (Lond) 2011; 25:1546-54. [PMID: 22020171 DOI: 10.1038/eye.2011.264] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
HYPOTHESIS Dark-adapted rods consume oxygen at high rates and light adaptation decreases this oxygen burden and can have therapeutic effects on diabetic macular oedema (DMO). METHODS Patients with mild non-proliferative diabetic retinopathy (DR) and early, untreated non-sight-threatening DMO slept for 6 months wearing masks that illuminated the eyelid of one closed eye by 505 nm light. Exclusion criteria were any concomitant eye disease, DR >ETDRS grade 35, and other systemic diseases. PRIMARY OUTCOME change of OCT retinal thickness in the local region where oedema was present. RESULTS A total of 34 out of 40 patients completed the study. Mean baseline OCT macular cube thickness was equivalent for study and fellow eyes. But study eyes had a greater mean thickness in the central subfield zone 1 (282±53 μm) vs (256±19 μm) the fellow eyes. Twenty-eight study eyes showed intraretinal cysts compared with nine in the fellow eyes. At 6 months, only 19 study eyes had cysts while cysts were seen in 20 fellow eyes. After 6 months, the worst affected ETDRS zone and the central subfield zone 1 reduced in thickness in study eyes only by 12 μm (95% CI 20 to -7, P=0.01). The secondary outcomes of change in visual acuity, achromatic contrast sensitivity, and microperimetric thresholds improved significantly in study eyes and deteriorated in fellow eyes. CONCLUSIONS Sleeping in dim light that can keep rods light adapted may reverse the changes of DMO.
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Affiliation(s)
- G B Arden
- School of Community and Health Sciences, City University, London, UK.
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