Expected Policy Gradient for Network Aggregative Markov Games in Continuous Space.

In this article, we investigate the Nash-seeking problem of a set of agents, playing an infinite network aggregative Markov game. In particular, we focus on a noncooperative framework where each agent selfishly aims at maximizing its long-term average reward without having explicit information on the model of the environment dynamics and its own reward function. The main contribution of this article is to develop a continuous multiagent reinforcement learning (MARL) algorithm for the Nash-seeking problem in infinite dynamic games with convergence guarantee. To this end, we propose an actor-critic MARL algorithm based on expected policy gradient (EPG) with two general function approximators to estimate the value function and the Nash policy of the agents. We consider continuous state and action spaces and adopt a newly proposed EPG to alleviate the variance of the gradient approximation. Based on such formulation and under some conventional assumptions (e.g., using linear function approximators), we prove that the policies of the agents converge to the unique Nash equilibrium (NE) of the game. Furthermore, an estimation error analysis is conducted to investigate the effects of the error arising from function approximation. As a case study, the framework is applied on a cloud radio access network (C-RAN) by modeling the remote radio heads (RRHs) as the agents and the congestion of baseband units (BBUs) as the dynamics of the environment.

Analgesic Effect of Topical Sodium Diclofenac before Retinal Photocoagulation for Diabetic Retinopathy: A Randomized Double-masked Placebo-controlled Intraindividual Crossover Clinical Trial

PURPOSE: To evaluate the analgesic effect of topical sodium diclofenac 0.1% before retinal laser photocoagulation for diabetic retinopathy. METHODS: Diabetic patients who were candidates for peripheral laser photocoagulation were included in a randomized, placebo-controlled, intraindividual, two-period, and crossover clinical trial. At the first session and based on randomization, one eye received topical sodium diclofenac 0.1% and the other eye received an artificial tear drop (as placebo) three times before laser treatment. At the second session, eyes were given the alternate drug. Patients scored their pain using visual analogue scale (max, 10 cm) at both sessions. Patients and the surgeon were blinded to the drops given. Difference of pain level was the main outcome measure. RESULTS: A total of 200 eyes of 100 patients were enrolled. Both treatments were matched regarding the applied laser. Pain sensation based on visual analogue scale was 5.6 ± 3.0 in the treated group and 5.5 ± 3.0 in the control group. The calculated treatment effect was 0.15 (95% confidence interval, −0.27 to 0.58; p = 0.486). The estimated period effect was 0.24 (p = 0.530) and the carryover effect was not significant (p = 0.283). CONCLUSIONS: Pretreatment with topical sodium diclofenac 0.1% does not have any analgesic effect during peripheral retinal laser photocoagulation in diabetic patients.

Predictors and Outcomes of Vitrectomy and Silicone Oil Injection in Advanced Diabetic Retinopathy

PURPOSE: To evaluate visual and anatomical results and identify factors that influence vitrectomy and silicone oil (SO) injection outcomes in proliferative diabetic retinopathy (PDR). METHODS: This retrospective study included 236 eyes with PDR that were undergoing vitrectomy and SO injection with >3-month follow-up. The primary outcomes were final best-corrected visual acuity (BCVA) and retinal attachment rate. RESULTS: At the final visit (mean, 88 ± 58 weeks), complete, partial, and no retinal attachment were observed in 86.9%, 10.6%, and 2.5% of patients, respectively. A total of 155 eyes had experienced SO removal, while 81 had SO in place. The mean initial BCVA was 1.9 ± 0.7 logarithm of the minimum angle of resolution (logMAR) and significantly improved to 1.7 ± 0.8 logMAR (p = 0.001). Initial macular detachment (adjusted odds ratio [AOR], 0.25), development of iatrogenic break (AOR, 0.25), and use of heavy SO (AOR, 0.13) were independently associated with a lower risk of final retinal attachment, and SO removal was associated with a higher incidence (AOR, 7.55). Better baseline BCVA was associated with a higher risk of final BCVA ≥20 / 200. CONCLUSIONS: Despite an encouraging outcome based on anatomical data in advanced PDR treated with vitrectomy and SO, the functional prognosis was not satisfying for patients. Eyes with better vision at baseline had a more favorable prognosis, whereas eyes with initial macular detachment, intraoperative iatrogenic break, or heavy SO showed more unfavorable outcomes. In selected cases, extending the time of SO use did not worsen the prognosis.

Causes of Visual Impairment among Patients Referred to a Visual Rehabilitation Clinic in Iran

PURPOSE: Epidemiologic evaluation and investigating the causes of visual impairment in any society is a matter of concern and has a direct effect on the country's health care planning. In this study we describe causes of low vision and blindness in Iranian patients referred to rehabilitation clinics for taking vision aids. METHODS: In this cross-sectional study, visual acuity was classified based on best-corrected visual acuity in the better eye according to the World Health Organization definition (blindness, visual acuity [VA] < 20 / 400; severe visual impairment, VA < 20 / 200-20 / 400; mild to moderate visual impairment, VA < 20 / 60-20 / 200). The causes of blindness and low vision were determined using the 10th version of International Classification of Diseases based on the main cause in both eyes. To describe data, we used mean +/- SD and frequency. RESULTS: The study included 432 patients, 65% male, with a mean age of 43.6 +/- 25.5 years (range, 3 to 92 years). Mild to moderate visual impairment, severe visual impairment and blindness were present in 122 (28.8%), 196 (46.4%) and 105 (24.8%) of the patients, respectively. The main causes of visual impairment were retinal and choroidal diseases (74.5%), optic nerve and optic tract diseases (9.8%), vitreous and globe disorders (5.3%), congenital cataract (3.1%), and glaucoma (2.6%). The distribution pattern of the causes was similar in all age subgroups. CONCLUSIONS: Diseases of the retina and choroid are the main cause of visual impairment among patients referred to an academic visual rehabilitation clinic in Iran.

Intravitreal Bevacizumab for Treatment of Refractory Central Serous Choroidoretinopathy

In a clinical case series, 5 patients with not-resolved central serous choroidoretinopathy (CSC) lasting more than 1 year received one intravitreal bevacizumab injection (IVB, 1.25 mg) injection. All patients underwent a through ophthalmic examination 1 day, 1 week, and 1, 2, and 6 months after the injection. Best corrected visual acuity (BCVA) and central macular thickness were compared before and after treatment by optical coherence tomography. Mean BCVA was improved significantly (p = 0.020) from 0.60 +/- 0.25 to 0.50 +/- 0.18 and 0.29 +/- 0.19 logarithm of minimum angle of resolution at 6 and 18 weeks, respectively. Central macular thickness was also decreased significantly (p = 0.010) from 370 +/- 65 to 208 +/- 23 microm at 4 months. No recurrence was occurred during follow-up. IVB injection may have beneficial effect in the treatment of refractory CSC.

Diabetic Macular Edema Before and After Intravitreal Triamcinolone Injection

PURPOSE: To compare intravitreal triamcinolone acetonide (IVT) versus natural course in refractory diabetic macular edema. METHODS: In a prospective interventional case series, twenty five eyes with refractory DME which had been allocated to the sham group of a previous clinical trial underwent new examination and optical coherence tomography about 9 months after their first enrollment. Twenty eyes that met the inclusion criteria, visual acuity (VA) 200 micrometer, were treated by 4 mg IVT. Evaluations were repeated at 2 and 4 months post-injection to imitate the similar examination intervals after sham injection. Corrected visual acuity and macular thickness changes following IVT were compared to the corresponding changes after sham injection (the natural course). RESULTS: Visual acuity changes within and between each period were not statistically significant. Visual acuity decreased 0.08 & 0.09 logMAR by 2 months and 0.06 & 0.04 logMAR by 4 months after sham and IVT injections, respectively. The changes of macular thickness after IVT and sham intervention were not meaningful either. However, the difference between thickness changes by 4 months (52+/-50 micrometer increase after sham vs. 262+/-115 micrometer reduction after IVT) was significant (P=0.014). CONCLUSIONS: Concerning macular thickness, IVT has beneficial effect on refractory diabetic macular edema as opposed to observation. However, considering visual acuity, it does not induce significant difference in comparison to the natural course of the disease.

Diabetic Macular Edema Before and After Intravitreal Triamcinolone Injection

PURPOSE: To compare intravitreal triamcinolone acetonide (IVT) versus natural course in refractory diabetic macular edema. METHODS: In a prospective interventional case series, twenty five eyes with refractory DME which had been allocated to the sham group of a previous clinical trial underwent new examination and optical coherence tomography about 9 months after their first enrollment. Twenty eyes that met the inclusion criteria, visual acuity (VA) 200 micrometer, were treated by 4 mg IVT. Evaluations were repeated at 2 and 4 months post-injection to imitate the similar examination intervals after sham injection. Corrected visual acuity and macular thickness changes following IVT were compared to the corresponding changes after sham injection (the natural course). RESULTS: Visual acuity changes within and between each period were not statistically significant. Visual acuity decreased 0.08 & 0.09 logMAR by 2 months and 0.06 & 0.04 logMAR by 4 months after sham and IVT injections, respectively. The changes of macular thickness after IVT and sham intervention were not meaningful either. However, the difference between thickness changes by 4 months (52+/-50 micrometer increase after sham vs. 262+/-115 micrometer reduction after IVT) was significant (P=0.014). CONCLUSIONS: Concerning macular thickness, IVT has beneficial effect on refractory diabetic macular edema as opposed to observation. However, considering visual acuity, it does not induce significant difference in comparison to the natural course of the disease.

Intravitreal Triamcinolone Reinjection for Refractory Diabetic Macular Edema

PURPOSE: To evaluate the effect of intravitreal triamcinolone acetonide (IVT) reinjection on clinical and optical coherence tomographic features in refractory diabetic macular edema. METHODS: In a prospective interventional case series, all IVT treated patients enrolled in a previous clinical trial were recalled to have a new ophthalmologic examination and optical coherence tomography (OCT) performed. Eyes found suitable for reinjection received 4 mg IVT. Complete clinical examination and OCT were repeated at 2 and 4 months post-injection. The changes were statistically analyzed using a paired t test and were compared to the results of the first injections. RESULTS: Of all returning patients, 12 cases with complete records were considered candidates for reinjection. Visual acuity (VA) changes were not significant after the first and second interventions, although there was a relative improvement (0.14 logMAR) 2 months after the first injection. Reductions of central macular thickness (CMT) were 43+/-69 micrometer, and 40+/-69 micrometer after the first injection and 27+/-48 micrometer, 49+/-58 micrometer after the reinjection at 2 and 4 months, respectively. None of the mentioned changes was significant. After the second injection, however, intraocular pressure was elevated at both 2 and 4 months (3.6 and 2.4 mmHg respectively, P<0.05). Two months after the first administration, intraocular pressure was found to be raised significantly (5.58 mmHg, P=0.001). CONCLUSIONS: The transient beneficial effects of IVT on diabetic macular edema are not repeated with second injections. However, IVT-related ocular hypertension is more persistent after reinjection.