Retina

Retina Publications

Tian B, Al-Moujahed A, Bouzika P, Hu Y, Notomi S, Tsoka P, Miller JW, Lin H, Vavvas DG. Atorvastatin Promotes Phagocytosis and Attenuates Pro-Inflammatory Response in Human Retinal Pigment Epithelial Cells. Sci Rep 2017;7(1):2329.Abstract
Phagocytosis of daily shed photoreceptor outer segments is an important function of the retinal pigment epithelium (RPE) and it is essential for retinal homeostasis. RPE dysfunction, especially impairment of its phagocytic ability, plays an essential role in the pathogenesis of age-related macular degeneration (AMD). Statins, or HMG CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors, are drugs with multiple properties that have been extensively used to treat hyperlipidemia. However, their effect on RPE cells has not been fully elucidated. Here we report that high dose atorvastatin increased the phagocytic function of ARPE-19 cells, as well as rescue the cells from the phagocytic dysfunction induced by cholesterol crystals and oxidized low-density lipoproteins (ox-LDL), potentially by increasing the cellular membrane fluidity. Similar effects were observed when evaluating two other hydrophobic statins, lovastatin and simvastatin. Furthermore, atorvastatin was able to block the induction of interleukins IL-6 and IL-8 triggered by pathologic stimuli relevant to AMD, such as cholesterol crystals and ox-LDL. Our study shows that statins, a well-tolerated class of drugs with rare serious adverse effects, help preserve the phagocytic function of the RPE while also exhibiting anti-inflammatory properties. Both characteristics make statins a potential effective medication for the prevention and treatment of AMD.
Yonekawa Y, Wu W-C, Nitulescu CE, Chan PRV, Thanos A, Thomas BJ, Todorich B, Drenser KA, Trese MT, Capone A. PROGRESSIVE RETINAL DETACHMENT IN INFANTS WITH RETINOPATHY OF PREMATURITY TREATED WITH INTRAVITREAL BEVACIZUMAB OR RANIBIZUMAB. Retina 2017;Abstract
PURPOSE: Fibrovascular contraction and tractional retinal detachment (TRD) are recognized complications associated with the use of anti-vascular endothelial growth factor agents in vasoproliferative vitreoretinopathies. The authors characterize TRDs that developed after intravitreal bevacizumab or ranibizumab therapy for vascularly active retinopathy of prematurity. METHODS: This is an international, multicenter, interventional, retrospective, case series. Thirty-five eyes from 23 infants were included. Inclusion required anti-vascular endothelial growth factor treatment of Type 1 retinopathy of prematurity with progression to TRD. RESULTS: Mean gestational age was 26 ± 2 weeks, and mean birth weight was 873 ± 341 g. Mean postmenstrual age on the day of injection was 35 ± 2 weeks. Retinal detachment was noted a mean of 70 days (median, 34; range, 4-335) after injection. Eleven percent detached within 1 week, 23% within 2 weeks, and 49% within 4 weeks. The highest stage of retinopathy of prematurity noted was 4A in 29%, 4B in 37%, and 5 in 34% of eyes. Time to RD negatively correlated with postmenstrual age at the time of injection (Rho = -0.54; P < 0.01). Three TRD configurations were observed: 1) conventional peripheral elevated ridge or volcano-shaped Stage 5 detachment, 2) midperipheral detachment with tight circumferential vectors, and 3) very posterior detachment with prepapillary contraction. Full or partial reattachment was achieved with surgical intervention in 86% of eyes. CONCLUSION: Progressive atypical TRD may occur after anti-vascular endothelial growth factor injections for retinopathy of prematurity. The configuration of the detachment varies with the extent of primary retinal vascularization present at the time of treatment.
Olivares AM, Han Y, Soto D, Flattery K, Marini J, Molemma N, Haider A, Escher P, Deangelis MM, Haider NB. The Nuclear Hormone Receptor Gene Nr2c1 (Tr2) is a Critical Regulator of Early Retina Cell Patterning. Dev Biol 2017;Abstract
Nuclear hormone receptors play a major role in the development of many tissues. This study uncovers a novel role for testicular receptor 2 (Tr2, Nr2c1) in defining the early phase of retinal development and regulating normal retinal cell patterning and topography. The mammalian retina undergoes an overlapping yet biphasic period of development to generate all seven retinal cell types. We discovered that Nr2c1 expression coincides with development of the early retinal cells. Loss of Nr2c1 causes a severe vision deficit and impacts early, but not late retina cell types. Retinal cone cell topography is disrupted with an increase in displaced amacrine cells. Additionally, genetic background significantly impacts phenotypic outcome of cone photoreceptor cells but not amacrine cells. Chromatin-IP experiments reveal NR2C1 regulates early cell transcription factors that regulate retinal progenitor cells during development, including amacrine (Satb2) and cone photoreceptor regulators thyroid and retinoic acid receptors. This study supports a role for Nr2c1 in defining the biphasic period of retinal development and specifically influencing the early phase of retinal cell fate.
Gong Y, Fu Z, Liegl R, Chen J, Hellström A, Smith LEH. ω-3 and ω-6 long-chain PUFAs and their enzymatic metabolites in neovascular eye diseases. Am J Clin Nutr 2017;Abstract
Neovascular eye diseases, including retinopathy of prematurity, diabetic retinopathy, and age-related macular degeneration, threaten the visual health of children and adults. Current treatment options, including anti-vascular endothelial growth factor therapy and laser retinal photocoagulation, have limitations and are associated with adverse effects; therefore, the identification of additional therapies is highly desirable. Both clinical and experimental studies show that dietary ω-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs) reduce retinal and choroidal angiogenesis. The ω-3 LC-PUFA metabolites from 2 groups of enzymes, cyclooxygenases and lipoxygenases, inhibit [and the ω-6 (n-6) LC-PUFA metabolites promote] inflammation and angiogenesis. However, both of the ω-3 and the ω-6 lipid products of cytochrome P450 oxidase 2C promote neovascularization in both the retina and choroid, which suggests that inhibition of this pathway might be beneficial. This review summarizes our current understanding of the roles of ω-3 and ω-6 LC-PUFAs and their enzymatic metabolites in neovascular eye diseases.
Butler NJ, Moradi A, Salek SS, Burkholder BM, Leung TG, Dunn JP, Thorne JE. Acute retinal necrosis: presenting characteristics and clinical outcomes in a cohort of polymerase chain reaction-positive patients. Am J Ophthalmol 2017;Abstract
PURPOSE: To identify determinants of adverse outcomes in acute retinal necrosis (ARN), presenting characteristics and incidence rates of vision loss and ocular complications in a cohort of polymerase chain reaction (PCR)-positive eyes were analyzed. DESIGN: Retrospective, observational cohort study. METHODS: Forty-one eyes of 36 patients with clinically-diagnosed ARN, PCR-positive for herpes simplex virus or varicella zoster virus and evaluated between January 2002 and June 2013, were included. Main outcome measures included incidence rates of vision loss and retinal detachment (RD). RESULTS: Presenting visual acuity was generally poor (20/50 to >20/200 in 27%; 20/200 or worse in 56%). The incidence rate of ≤20/200 was 0.66/eye-year (EY), (95% CI, 0.32/EY - 1.22/EY); the rate of light perception or no light perception vision was 0.07/EY (95% CI, 0.02/EY - 0.16/EY). During follow-up, 59% of eyes developed at least one RD (rate = 0.40/EY, 95% CI, 0.19/EY - 0.58/EY). Eyes with retinitis involving ≥25% of the retina at presentation detached at nearly 12 times the rate, as compared to those with <25% retinal involvement (0.70/EY vs. 0.06/EY; p=0.001). Development of an RD was the greatest determinant of adverse visual outcomes, with 4% of eyes, that had experienced at least one RD, achieving a best-corrected visual acuity of ≥20/40 compared to 53% of eyes that never detached (p=0.0003). CONCLUSIONS: Poor outcomes in ARN were common in this cohort. RD confers the greatest risk of incident vision loss, and once 25% or more of the retina is involved the risk of RD and visual loss increases significantly.
Davoudi S, Ebrahimiadib N, Yasa C, Sevgi DD, Roohipoor R, Papavasilieou E, Comander J, Sobrin L. Outcomes in Autoimmune Retinopathy Patients Treated With Rituximab. Am J Ophthalmol 2017;Abstract
PURPOSE: To evaluate clinical and ancillary testing, including adaptive optics, outcomes in autoimmune retinopathy (AIR) patients treated with rituximab. DESIGN: Retrospective, interventional case series. METHODS: patients: Sixteen AIR patients treated with rituximab. OBSERVATION PROCEDURES: All patients were treated with a loading and maintenance dose schedule of intravenous rituximab. Visual acuity (VA), electroretinography (ERG), and spectral-domain optical coherence tomography (SDOCT) and visual field (VF) results were recorded. A subset of patients was also imaged using adaptive optics scanning laser ophthalmoscopy (AO-SLO). MAIN OUTCOME MEASURES: Rates of VA change before vs after rituximab initiation were compared with mixed-model linear regression. RESULTS: The rate of visual decline was significantly less after rituximab initiation compared with the rate of visual decline prior to rituximab initiation (P = .005). Seventy-seven percent of eyes had stable or improved VA 6 months after rituximab initiation. Amplitudes and implicit times on ERG, mean deviation on VF, central subfield mean thickness, and total macular volume did not decrease to a significant degree over the rituximab treatment period. Six eyes had serial AO-SLO imaging. Cone densities did not change significantly over the treatment period. CONCLUSION: VA was stable or improved in a majority of AIR patients while they were being treated with rituximab. OCT and ERG parameters, as well as AO-SLO cone densities, were stable during treatment. Studies with additional patients and longer follow-up periods are needed to further explore the utility of rituximab in the management of AIR.
Wallace DK, Kraker RT, Freedman SF, Crouch ER, Hutchinson AK, Bhatt AR, Rogers DL, Yang MB, Haider KM, VanderVeen DK, Siatkowski MR, Dean TW, Beck RW, Repka MX, Smith LE, Good WV, Hartnett ME, Kong L, Holmes JM, Holmes JM. Assessment of Lower Doses of Intravitreous Bevacizumab for Retinopathy of Prematurity: A Phase 1 Dosing Study. JAMA Ophthalmol 2017;Abstract

Importance: Intravitreous bevacizumab (0.25 to 0.625 mg) is increasingly used to treat type 1 retinopathy of prematurity (ROP), but there remain concerns about systemic toxicity. A much lower dose may be effective while reducing systemic risk. Objective: To find a dose of intravitreous bevacizumab that was lower than previously used for severe ROP, was effective in this study, and could be tested in future larger studies. Design, Setting, and Participants: Between May 2015 and September 2016, 61 premature infants with type 1 ROP in 1 or both eyes were enrolled in a masked, multicenter, phase 1 dose de-escalation study. One eye of 10 to 14 infants received 0.25 mg of intravitreous bevacizumab. If successful, the dose was reduced for the next group of infants (to 0.125 mg, then 0.063 mg, and finally 0.031 mg). Diluted bevacizumab was delivered using 300 µL syringes with 5/16-inch, 30-gauge fixed needles. Interventions: Bevacizumab injections at 0.25 mg, 0.125 mg, 0.063 mg, and 0.031 mg. Main Outcomes and Measures: Success was defined as improvement in preinjection plus disease or zone I stage 3 ROP by 5 days after injection or sooner, and no recurrence of type 1 ROP or severe neovascularization requiring additional treatment within 4 weeks. Results: Fifty-eight of 61 enrolled infants had 4-week outcomes completed; mean birth weight was 709 g and mean gestational age was 24.9 weeks. Success was achieved in 11 of 11 eyes at 0.25 mg, 14 of 14 eyes at 0.125 mg, 21 of 24 eyes at 0.063 mg, and 9 of 9 eyes at 0.031 mg. Conclusions and Relevance: A dose of bevacizumab as low as 0.031 mg was effective in 9 of 9 eyes in this phase 1 study and warrants further investigation. Identifying a lower effective dose of bevacizumab may reduce the risk for neurodevelopmental disability or detrimental effects on other organs.

Brodowska K, Stryjewski TP, Papavasileiou E, Chee YE, Eliott D. Validation of the Retinal Detachment after Open Globe Injury (RD-OGI) Score as an Effective Tool for Predicting Retinal Detachment. Ophthalmology 2017;124(5):674-678.Abstract

PURPOSE: The Retinal Detachment after Open Globe Injury (RD-OGI) Score is a clinical prediction model that was developed at the Massachusetts Eye and Ear Infirmary to predict the risk of retinal detachment (RD) after open globe injury (OGI). This study sought to validate the RD-OGI Score in an independent cohort of patients. DESIGN: Retrospective cohort study. PARTICIPANTS: The predictive value of the RD-OGI Score was evaluated by comparing the original RD-OGI Scores of 893 eyes with OGI that presented between 1999 and 2011 (the derivation cohort) with 184 eyes with OGI that presented from January 1, 2012, to January 31, 2014 (the validation cohort). METHODS: Three risk classes (low, moderate, and high) were created and logistic regression was undertaken to evaluate the optimal predictive value of the RD-OGI Score. A Kaplan-Meier survival analysis evaluated survival experience between the risk classes. MAIN OUTCOME MEASURES: Time to RD. RESULTS: At 1 year after OGI, 255 eyes (29%) in the derivation cohort and 66 eyes (36%) in the validation cohort were diagnosed with an RD. At 1 year, the low risk class (RD-OGI Scores 0-2) had a 3% detachment rate in the derivation cohort and a 0% detachment rate in the validation cohort, the moderate risk class (RD-OGI Scores 2.5-4.5) had a 29% detachment rate in the derivation cohort and a 35% detachment rate in the validation cohort, and the high risk class (RD-OGI scores 5-7.5) had a 73% detachment rate in the derivation cohort and an 86% detachment rate in the validation cohort. Regression modeling revealed the RD-OGI to be highly discriminative, especially 30 days after injury, with an area under the receiver operating characteristic curve of 0.939 in the validation cohort. Survival experience was significantly different depending upon the risk class (P < 0.0001, log-rank chi-square). CONCLUSIONS: The RD-OGI Score can reliably predict the future risk of developing an RD based on clinical variables that are present at the time of the initial evaluation after OGI.

Spencer C, Abend S, McHugh KJ, Saint-Geniez M. Identification of a synergistic interaction between endothelial cells and retinal pigment epithelium. J Cell Mol Med 2017;Abstract

The retinal pigment epithelium located between the neurosensory retina and the choroidal vasculature is critical for the function and maintenance of both the photoreceptors and underlying capillary endothelium. While the trophic role of retinal pigment epithelium on choroidal endothelial cells is well recognized, the existence of a reciprocal regulatory function of endothelial cells on retinal pigment epithelium cells remained to be fully characterized. Using a physiological long-term co-culture system, we determined the effect of retinal pigment epithelium-endothelial cell heterotypic interactions on cell survival, behaviour and matrix deposition. Human retinal pigment epithelium and endothelial cells were cultured on opposite sides of polyester transwells for up to 4 weeks in low serum conditions. Cell viability was quantified using a trypan blue assay. Cellular morphology was evaluated by H&E staining, S.E.M. and immunohistochemistry. Retinal pigment epithelium phagocytic function was examined using a fluorescent bead assay. Gene expression analysis was performed on both retinal pigment epithelium and endothelial cells by quantitative PCR. Quantification of extracellular matrix deposition was performed on decellularized transwells stained for collagen IV, fibronectin and fibrillin. Our results showed that presence of endothelial cells significantly improves retinal pigment epithelium maturation and function as indicated by the induction of visual cycle-associated genes, accumulation of a Bruch's membrane-like matrix and increase in retinal pigment epithelium phagocytic activity. Co-culture conditions led to increased expression of anti-angiogenic growth factors and receptors in both retinal pigment epithelium and endothelial cells compared to monoculture. Tube-formation assays confirmed that co-culture with retinal pigment epithelium significantly decreased the angiogenic phenotype of endothelial cells. These findings provide evidence of critical interdependent interactions between retinal pigment epithelium and endothelial cell involved in the maintenance of retinal homeostasis.

Olivares AM, Jelcick AS, Reinecke J, Leehy B, Haider A, Morrison MA, Cheng L, Chen DF, DeAngelis MM, Haider NB. Multimodal Regulation Orchestrates Normal and Complex Disease States in the Retina. Sci Rep 2017;7(1):690.Abstract

Regulation of biological processes occurs through complex, synergistic mechanisms. In this study, we discovered the synergistic orchestration of multiple mechanisms regulating the normal and diseased state (age related macular degeneration, AMD) in the retina. We uncovered gene networks with overlapping feedback loops that are modulated by nuclear hormone receptors (NHR), miRNAs, and epigenetic factors. We utilized a comprehensive filtering and pathway analysis strategy comparing miRNA and microarray data between three mouse models and human donor eyes (normal and AMD). The mouse models lack key NHRS (Nr2e3, RORA) or epigenetic (Ezh2) factors. Fifty-four total miRNAs were differentially expressed, potentially targeting over 150 genes in 18 major representative networks including angiogenesis, metabolism, and immunity. We identified sixty-eight genes and 5 miRNAS directly regulated by NR2E3 and/or RORA. After a comprehensive analysis, we discovered multimodal regulation by miRNA, NHRs, and epigenetic factors of three miRNAs (miR-466, miR1187, and miR-710) and two genes (Ell2 and Entpd1) that are also associated with AMD. These studies provide insight into the complex, dynamic modulation of gene networks as well as their impact on human disease, and provide novel data for the development of innovative and more effective therapeutics.

Veronese C, Staurenghi G, Pellegrini M, Maiolo C, Primavera L, Morara M, Armstrong GW, Ciardella AP. MULTIMODAL IMAGING IN VORTEX VEIN VARICES. Retin Cases Brief Rep 2017;Abstract

PURPOSE: The aim of this study is to describe the clinical presentation of vortex vein varices with multimodal imaging. METHODS: The authors carried out a retrospective case series of eight patients (7 female, 1 male) with an average age of 60.2 years (min 8, max 84, median 68.5) presenting with vortex vein varices. All patients were evaluated at the Sant'Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy and at Luigi Sacco Hospital, University of Milan, Milan, Italy. Patients underwent complete ophthalmologic examinations, including best corrected visual acuity, intraocular pressure, anterior segment, and fundus examination. Imaging studies, including fundus color photography, near-infrared reflectance imaging, fundus autofluorescence, fluorescein angiography, indocyanine green angiography, and spectral-domain enhanced depth imaging optical coherence tomography were also performed. Ultra-widefield fluorescein angiography and ultra-widefield indocyanine angiography using the Heidelberg Retina Angiograph and the Staurenghi 230 SLO Retina Lens were used to demonstrate the disappearance of all retinal lesions when pressure was applied to the globe. RESULTS: All eight cases initially presented to the emergency room. One patient presented secondary to trauma, two patients presented for suspected hemangioma, whereas the other five were referred to the authors' hospitals for suspected retinal lesions. On examination, retinal abnormalities were identified in all 8 patients, with 7 (87.5%) oculus dexter and 1 (12.5%) oculus sinister, and with 1 (12.5%) inferotemporally, 3 (37.5%) superonasally, 3 (37.5%) inferonasally, and 1 (12.5%) inferiorly. Fundus color photography showed an elevated lesion in seven patients and a nonelevated red lesion in one patient. In all patients, near-infrared reflectance imaging showed a hyporeflective lesion in the periphery of the retina. Fundus autofluorescence identified round hypofluorescent rings surrounding weakly hyperfluorescent lesions in all patients. On fluorescein angiography, all lesions were initially hyperfluorescent with a hypofluorescent ring, with the lesion becoming hyperfluorescent after injection of dye. Indocyanine green angiography demonstrated dilation of the vortex vein ampullae in all patients. Spectral-domain enhanced depth imaging optical coherence tomography demonstrated dilated choroidal vessels and a hyporeflective cavity without subretinal fluid in all patients. Ultra-widefield fluorescein angiography and ultra-widefield indocyanine angiography demonstrated disappearance of all retinal lesions when pressure was applied to the globe. Findings are consistent with the diagnosis of vortex vein varix in all eight patients, with six patients (75%) exhibiting a single varix and two patients (25%) exhibiting a double varix. CONCLUSION: The diagnosis of vortex vein varices can be confirmed through clinical examination through the use of digital pressure to the globe during ophthalmoscopic examination. Adjunctive multimodal imaging (fundus color photography, near-infrared reflectance imaging, fundus autofluorescence, fluorescein angiography, indocyanine angiography, and spectral-domain enhanced depth imaging optical coherence tomography) was useful in the diagnosis of vortex vein varices in the authors' clinical cases. However, in more challenging clinical cases, the authors' novel use of the ultra-widefield contact lens for application of ocular pressure with a resulting resolution of the varix proved to be a useful and easy diagnostic imaging method for confirming the presence of vortex vein varices.

VanderVeen DK, Melia M, Yang MB, Hutchinson AK, Wilson LB, Lambert SR. Anti-Vascular Endothelial Growth Factor Therapy for Primary Treatment of Type 1 Retinopathy of Prematurity: A Report by the American Academy of Ophthalmology. Ophthalmology 2017;124(5):619-633.Abstract

PURPOSE: To review the available evidence on the ocular safety and efficacy of anti-vascular endothelial growth factor (VEGF) agents for the treatment of retinopathy of prematurity (ROP) compared with laser photocoagulation therapy. METHODS: A literature search of the PubMed and Cochrane Library databases was conducted last on September 6, 2016, with no date restrictions and limited to articles published in English. This search yielded 311 citations, of which 37 were deemed clinically relevant for full-text review. Thirteen of these were selected for inclusion in this assessment. The panel methodologist assigned ratings to the selected articles according to the level of evidence. RESULTS: Of the 13 citations, 6 articles on 5 randomized clinical trials provided level II evidence supporting the use of anti-VEGF agents, either as monotherapy or in combination with laser therapy. The primary outcome for these articles included recurrence of ROP and the need for retreatment (3 articles), retinal structure (2 articles), and refractive outcome (1 article). Seven articles were comparative case series that provided level III evidence. The primary outcomes included the effects of anti-VEGF treatment on development of peripheral retinal vessels (1 article), refractive outcomes (1 article), or both structural and refractive or visual outcomes (5 articles). CONCLUSIONS: Current level II and III evidence indicates that intravitreal anti-VEGF therapy is as effective as laser photocoagulation for achieving regression of acute ROP. Although there are distinct ocular advantages to anti-VEGF pharmacotherapy for some cases (such as eyes with zone I disease or aggressive posterior ROP), the disadvantages are that the ROP recurrence rate is higher, and vigilant and extended follow-up is needed because retinal vascularization is usually incomplete. After intravitreal injection, bevacizumab can be detected in serum within 1 day, and serum VEGF levels are suppressed for at least 8 to 12 weeks. The effects of lowering systemic VEGF levels on the developing organ systems of premature infants are unknown, and there are limited long-term data on potential systemic and neurodevelopmental effects after anti-VEGF use for ROP treatment. Anti-VEGF agents should be used judiciously and with awareness of the known and unknown or potential side effects.

Schuerch K, Woods RL, Lee W, Duncker T, Delori FC, Allikmets R, Tsang SH, Sparrow JR. Quantifying Fundus Autofluorescence in Patients With Retinitis Pigmentosa. Invest Ophthalmol Vis Sci 2017;58(3):1843-1855.Abstract

Purpose: Using quantitative fundus autofluorescence (qAF), we analyzed short-wavelength autofluorescent (SW-AF) rings in RP. Methods: Short-wavelength autofluorescent images (486 nm excitation) of 40 patients with RP (69 eyes) were acquired with a confocal scanning laser ophthalmoscope equipped with an internal fluorescent reference. Mean qAF was measured in eight preset segments (qAF8) and in region of interest (ROI)-qAF (200-700 μm) within and external to the borders of the rings at superior, temporal, and inferior sites relative to the ring. For both groups, qAF in patients with RP was compared to age-similar and race/ethnicity-matched healthy eyes at equivalent retinal locations. Results: In 71% of eyes of RP patients, qAF8 acquired internal to the inner border of the ring, was within the 95% confidence interval (CI) for healthy eyes, while in the remaining RP eyes qAF8 was either higher or lower than the CI. Measured external to the ring, qAF8 values were within the CI in 47% of RP eyes with the other eyes being higher or lower. In 28% of sites measured by ROI-qAF within the SW-AF ring, values were above the 95% CI of healthy controls. Region of interest-qAF measured just external to the ring was within the CI of healthy eyes in 74% of locations. The average local elevation in qAF within the ring was approximately 15%. In SD-OCT scans, photoreceptor-attributable reflectivity bands were thinned within and external to the ring. Conclusions: Increased fluorophore production may be a factor in the formation of the SW-AF rings in RP.

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