Electrophysiological evidence for cross-modal plasticity in humans with early- and late-onset blindness

It is commonly believed that sensory deprivation can lead to cross-modal reorganization in an immature hut not in a mature brain. The results of the present study suggest, however, that plasticity between sensory modalities is possible even in adults: activity indicating involvement of parietal or occipital brain areas in pitch-change discrimination was found in individuals blinded after childhood. Event-related brain potentials of early blinded (before the age of 2 years). late-blinded (12–28 years of age), and sighted adults were recorded to stimulus sequences consisting of standard tones occasionally replaced by deviant tones. Even when participants were not attending to auditory stimuli, the deviant tones elicited the mismatch negativity (MMN) in each group. There were no significant MMN front-back scalp distribution differences among the groups. However, when participants were detecting deviant stimuli, these stimuli elicited N2 and P3 waves that were posterior in distribution in both groups of blind participants relative to those of the sighted participants. These results suggest that cross-modal reorganization may occur even in the mature human brain.     

Causes of secondary glaucoma in Paraguay

Summary Glaucoma is the third-most-frequent cause of blindness in the world, with a total of 5.2 million blind people as a result of this disease; 80 % live in developing countries. In Paraguay, after cataract it is the second-most-frequent-cause. Early detection of the risk factors and groups can help to avoid progress of this disease. Trauma, cataract and infectious uveitis represent special risks for developing secondary glaucoma, which is a more frequent cause of blindness in third-world countries than in industrialized nations. Until now there has been little data regarding the causes, disease course, and options for therapy. Therefore, secondary glaucoma was examined in Paraguay to obtain information on the situation in Latin America. The aim of the study was to explore the causes of secondary glaucoma for programs concerning prevention and therapy. From November 1996 to February 1997 patients with secondary glaucoma were examined at the University Hospital of Asunción, Paraguay. After the clinical examination the secondary glaucomas were classified. Patients with primary glaucoma were included in the same period of time as well in order to get the rate of secondary glaucoma. Altogether 293 patients were examined: 61 with secondary and 232 with primary glaucoma. The causes of secondary glaucoma in 73 eyes were: 20 (27 %) with pseudoexfoliation glaucoma, 19 (26 %) with post-traumatic glaucoma, 16 (22 %) with neovascular glaucoma, 4 (5 %) with lens-related glaucoma, 3 (4 %) with glaucoma associated with ocular surgery, 2 (3 %) with pigmentary and 2 (3 %) with corticoid-induced glaucoma. A ratio of 4:1 primary glaucomas to secondary glaucomas was found. The development of special measures for prevention and early therapy is only possible if the causes of this severe disease are explored. The results of this study represent basic information and could help to introduce of prevention programs.      

Ictal Cortical Blindness with Permanent Visual Loss

Cortical blindness is rarely an ictal manifestation. We report the case of a man who developed transient cortical blindness followed by permanent visual deficits during repeated partial seizures. Intermittent visual impairment began at age 14 years. After he had the first generalized seizure at age 28 years, neurologic, ophthalmologic, angiographic, and brain computed tomographic (CT) examinations were normal. Several EEGs showed almost continuous biposterior spike-waves. Over the next several years, frequent partial seizures were associated with transient visual loss and left body twitching or paresthesias. When he was 32, transient blindness occurred during several days of repeated occipital seizures. Permanent left homonymous hemianopia, right homonymous central scotoma, dyschromatopsia, and altered stereopsis followed these seizures. Brain CT demonstrated a new right occipital lesion. Partial seizures arising posteriorly may cause transient cortical blindness and result in permanent visual deficits.     

Diabetic Retinopathy as a Cause of Blindness in the Province of Turin,North-west Italy,in 1967–1991

Diabetes is known to be a major contributor to blindness in industrialized countries but few data are available on the situation in Italy. As an introductory step to the implementation of permanent screening for diabetic retinopathy, a search was carried out on the causes of visual loss in the provincial territory surrounding Turin, the main city of North-West Italy. The case notes of all 4549 residents in the province who were certified blind between 1967 and 1991 were examined with regard to cause, age at onset, and year of onset of visual acuity 1/20. Diabetic retinopathy was the second commonest cause of bilateral blindness (13.1 % of cases), preceded by cataract (26.7%) and followed by myopia (11.1%), optic atrophy (8.9%), glaucoma (8.9%), retinitis pigmentosa (7.2%), and senile macular degeneration (4.1%). Diabetic retinopathy was the commonest eye disease among those who became blind between the ages of 50 and 70 and remained the leading cause of visual loss when the age groups 20 to 70 were pooled together. The incidence of diabetic retinopathy-related blindness did not show any trend to decrease over the 25 years investigated. It is concluded that, in spite of widespread availability of facilities for its assessment and treatment, diabetic retinopathy remains a leading cause of blindness in North-West Italy. This fully justifies the implementation of screening programmes and efficient referral chains for the early detection and prompt treatment of this complication of diabetes.     

Unilateral esotropia after enucleation in infancy

Five patients developed esotropia in the remaining eye after unilateral enucleation in the first few weeks to months of life. Esotropia was associated with a face turn toward the opposite side and abduction nystagmus with a null point in extreme adduction. Our experience with these patients supports the reflexogenic theory for the development of a type of congenital-infantile esotropia. An intact globe-ocular muscle relationship, even in a blind eye, may have a stabilizing effect on the fellow eye in the first few weeks to months of life, and this should be considered before enucleation is done.     

南通市新城桥街道60岁及以上人群盲和低视力的现况调查

目的调查江苏省南通市城市人口中60岁及以上人群盲和低视力的患病率及其原因。方法采用随机整群抽样方法,抽取新城桥街道14个社区中的8个,并对所有60岁及以上人群进行检查。分别检查小孔视力和日常生活视力,应用裂隙灯显微镜和直接检眼镜等仪器检查受检者外眼、眼前节及眼底等情况。正式调查前先进行预试验。结果共检录3352人,受检人数为3040人,应答率90．69％。按小孔视力和世界卫生组织视力损伤标准,双眼盲和低视力患病率分别为1．35％和1．84％,其中女性分别为1．92％和2．33％,男性为0．66％和1．24％;盲和低视力患病率随着年龄的增长而增加;致盲和低视力的首要原因为白内障。按日常生活视力和视力损伤标准,双眼盲和视力损伤的患病率分别为1．58％和13．59％,其中女性分别为2．10％和15．98％,男性为0．95％和10．66％;盲和视力损伤的患病率亦随年龄的增长而增加;致双眼盲的首要原因亦为白内障。结论南通市60岁及以上城市人群盲的患病率低于华北、华南及西部地区。女性与文盲的盲和低视力患病率分别高于男性与非文盲。南通市城市人口中致盲的主要原因依次为白内障、眼底异常、屈光不正及角膜瘢痕或混浊等。     

Permanent Blindness after Endoscopic Sinus Surgery

Few cases of ophthalmic complications have been reported following sinus endoscopic surgery with current techniques. Irreversible damage to orbital structures was found in a 21-year-old patient referred to our department for evaluation after sinus endoscopic surgery and ipsilateral amaurosis.     

Cataract blindness in Paraguay – results of a national survey

PURPOSE To estimate the burden of visual loss and blindness due to cataract in people aged 50 years and over in Paraguay. METHODS Forty clusters of 60 persons each who were 50 years and older (2400 eligible persons) were selected by systematic random sampling from the entire population of Paraguay.A total of 2136 persons were examined (89% coverage). RESULTS For the population 50 years and over, the age- and gender- adjusted prevalence of bilateral blindness (VA < 3/60 with available correction) was 3.14% (95% CI: 2.2–4.4). The adjusted prevalence of bilateral cataract blindness (VA < 3/60) was 2.01% (95% CI: 1.3–3.0), making cataract the major cause of bilateral blindness in this age group (64%). The adjusted prevalence of bilateral severe visual impairment (VA < 6/60 with available correction) was 5.17% (95% CI: 3.9–6.7) and the adjusted prevalence of severe visual impairment due to bilateral cataract (VA < 6/60) was 3.09% (95% CI: 2.2–4.3). The cataract surgical coverage (persons) was 44% for bilaterally blind persons with VA < 3/60; 36% for persons with bilateral VA < 6/60; and 28% for any eye with VA < 6/60 due to cataract. With IOL implantation, 77% of the operated eyes could see 6/18, against 46% of the non-IOLs (p < 0.005), a significant better outcome. CONCLUSIONS There is a need to increase the cataract surgical coverage in Paraguay. The number of eye surgeons is adequate but the accessibility of cataract surgical services in rural areas and the affordability of surgery to large sections of society are major constraints.     

上海市艾滋病初诊患者眼部并发症及致盲原因调查分析

目的 调查上海市获得性免疫缺陷综合征(艾滋病,AIDS)初诊患者的眼部并发症的发生情况,分析其损害视力的主要因素,为防治视力损伤提供依据.方法 横断面研究.于2011年3月～2012年2月期间对上海市公共卫生临床中心就诊的AIDS初诊患者进行调查,进行一系列完整的眼科及全身检查.采用Snellen视力表检查裸眼远视力和最佳矫正远视力;采用裂隙灯和眼底镜进行眼前段和眼底检查.对录入数据按WHO视力损害标准分级,并分析肓和低视力损害的原因.对数据进行分类计数,求百分比,用卡方检验进行数据分析.结果 358例艾滋病初诊患者中,286名患者知情同意至眼科门诊参加检查,受检率79.9％.眼部并发症患病率58.4％(167/286),其中干眼症的患病率最高36.0％(103/286),其次是结膜炎19.9％(57/286)、巨细胞病毒性视网膜炎(CMVR) 8.39％ (24/286)等.致盲率据首位的是CMVR40.0％ (4/10),其次是均为30.0％(3/10)的视网膜微血管病变(HIVM)和青光眼等.致盲性眼病在CD4+F淋巴细胞水平低于250个/μl时高发.结论 上海市AIDS初诊患者眼部并发症患病率高于美国等国家,CMVR是主要损害视力的原因,建议加快建立健全CMVR的筛查和诊治网络,提高AIDS患者的生存质量.