Linkage studies and mutation analysis of the PDEB gene in 23 families with Leber congenital amaurosis.

The phenotype in the rd mouse is similar to the clinical presentation of Leber congenital amaurosis (LCA) in humans. Recently a nonsense mutation in the beta subunit of the cGMP phosphodiesterase (Pdeb) gene has been defined as the cause for the rd phenotype in the mouse and has raised the question as to whether mutations in the human PDEB gene might cause LCA. We have previously cloned and characterized the human homologue of the mouse Pdeb gene and have mapped it to chromosome 4p16.3. In this study, a total of 23 LCA families of various ethnic backgrounds have been investigated. Linkage analysis using highly polymorphic (CA)n microsatellites has excluded the PDEB gene as a cause for LCA in 6 families. In the remaining 17 families, we have searched for mutations in the 22 exons of the PDEB gene using single-strand gel electrophoresis (SSGE). Multiple exonic polymorphisms have been determined. However, no DNA changes in the PDEB gene have been identified in our study population which could be causative for the LCA phenotype.     

Retinal specificity in eye fragments: investigations on the retinotectal projections of different quarter-eyes in Xenopus laevis

According to Sperry's chemoaffinity hypothesis, the projection of a small eye fragment with a reduced amount of optic fibres should be restricted to that position in the optic tectum corresponding to its own specificity. However, previous investigations on different types of quarter-eyes in Xenopus laevis have revealed that their retinal projection was always restricted to the rostral part of the tectum, no matter what the origin of the remaining retinal quadrant. To get an indication of the state of specificity in such eye fragments, we investigated by electrophysiological and histological methods several features of the retinal projections of temporoventral (TV), naso-ventral (NV) and ventral (V) quarter-eyes which referred to their positional identity. Irrespective of their different origins, the projections were always located in the rostral part of the tectum, the size of the innervated tectal area depending for all fragment types on the size of the quarter-eyes, i.e. number of optic fibres. However, quantitative analyses revealed that with increasing eye size the various fragments expand their projections preferentially into those tectal areas that match their original specificity: TV projection is more concentrated in the rostral tectum, NV eyes expand their projections mainly to the caudal tectum, and V eyes enlarge their projections equally into the medial and caudal tectum. In addition, fibre-tracing experiments with cobaltic lysine showed that, according to the different origins of the quarter-eyes, retinal fibres follow the appropriate branch of the optic tract selectively: fibres of NV and V eyes pass mainly through the medial tract, and most fibres of TV eyes innervate the rostral tectum directly from a central position between the two side branches. All these findings suggest that the different types of quarter-eyes retain their original positional identity. Thus, their rostrally located retinotectal projections are not in register with their retinal specificity. We conclude that in X. laevis local positional markers in the tectum, if present at all, do not influence the development of the retinotectal projection. Instead we suggest a concept of self-sorting of the optic fibres, which can account for the partial innervation of the rostral tectum in different types of quarter-eyes.     

143例孔源性视网膜脱离临床分析

本文分析了１４３例（１４７眼）孔源性视网膜脱离的一般临床资料、眼部情况、手术类型及治疗结果。本组出院时１３６眼痊愈（９２．５％）；随访２月至６年的４３眼中３４眼痊愈（７９．０％）。讨论了视网膜脱离的易发因素、术式选择、手术注意事项和预后。     

玻璃体腔内注气治疗黄斑裂孔视网膜脱离

采用玻璃体腔内注气治疗黄斑裂孔视网膜脱离４９例（５３只眼），视风膜复位４２只眼（７９．２％），其中术后视力增进２９只眼（６９％），讨论了注气的适应征和影响视网膜复位的因素。     

环扎加压术治疗大裂孔视网膜脱离

目的：探讨环扎加压术对大裂孔视网膜脱离的疗效。方法：回顾分析1998年12月至2001年12月进行环扎加压术的大裂孔视网膜脱离病例33例33眼。结果：环扎加压术1次手术成功率78．79％，未愈7例中3例再行环扎加压术治愈，总治愈率达87．88％。结论：环扎加压术对于单纯型大裂孔视网膜脱离实为一种有效的治疗方法。眼内气体填充是治疗有翻转后瓣的大裂孔网脱的有效手段。     

玻璃体切除术联合眼内填充治疗复杂性视网膜脱离

目的：讨论玻璃体切除术联合眼内C3F8或硅油填充治疗复杂性视网膜脱离的效果。方法：对61例(61眼)复杂性视网膜脱离患行玻璃体切除联合冷冻、惰性气体C3F8或硅油眼内充填治疗，术后密切观察随访6个月．结果；玻璃体切除联合冷冻、惰性气体C3F8或硅油眼内充填治疗术后视网膜解剖复位49例，其中行最后随访时的视网膜复位率80．3％。视网膜复位眼最后视力均有不同程度的提高。结论：玻璃体切除术联合眼内填充治疗复杂性视网膜脱离有良好的疗效，解除视网膜牵引及合理选择充填物是手术成功的关键。     

Retinal photoreceptor fine structure in the velvet cichlid (Astronotus ocellatus).

Summary The structure and arrangement of the retinal photoreceptors of the velvet cichlid fish (Astronotus ocellatus) have been studied by light and electron microscopy. Rods, single cones and double (twin) cones are present. In the light-adapted state, rods are very tall cells that reach deep into the retinal epithelial (RPE) layer. The long outer segment is composed of discs of uniform diameter displaying one or two incisures. The rod inner segment shows a distal ellipsoid of mitochondria, and then narrows dramatically in the myoid region. Rod nuclei are electron dense and located deep in the outer nuclear layer. Rod synaptic spherules are small and show two to three invaginated synaptic sites as well as superficial synapses. Single cones are similar to the individual members of a double cone and all display a short tapering outer segment, a large ellipsoid of mitochondria and a myoid rich in rough endoplasmic reticulum, polysomes, Golgi zones and autophagic vacuoles. Double cones have extensive subsurface cisternae along their entire contiguous surfaces. Cone nuclei are large and vesicular and located close to or through the external limiting membrane. The synaptic pedicles of cones are larger, more electron lucent, and display more invaginated (ribbon) synapses as well as conventional (superficial) synaptic sites than do the rod spherules. Rod photoreceptors certainly undergo retinomotor movements and it is probable that cones do as well. In the light-adapted state the cone photoreceptors are arranged in a repeating square mosaic pattern with one single cone surrounded by four double (twin) cones.     

7岁以下儿童视网膜脱离

分析了7岁以下儿童视网膜脱离(RD)21例。儿童裂孔源性RD主要由外伤引起,非裂孔源性RD多与遗传、发育异常、Coat's病、眼内感染等因素有关。本文还讨论了儿童外伤性RD的临床特点和预防措施,强调了孕产期妇女保健对预防儿童非外伤性RD的意义。     

急进性后极部早产儿视网膜病变的临床进程及疗效观察

目的 描述急进性后极部早产儿视网膜病变(AP-ROP)的临床进程及特征,评价视网膜光凝及冷凝对急进性后极部早产儿视网膜病变的治疗效果.方法 前瞻性、非对比性、连续性病例.2006年1月至2008年6月经检查确诊为急进性后极部ROP的患儿8例16只眼.确诊后24h内行间接眼底镜下行视网膜光凝治疗联合或不联合直视下冷凝治疗.结果 急进性后极部早产儿视网膜病变以病变大部分位于后极部1区,所有象限视网膜血管扩张迂曲,病程进展快,若不及时治疗,迅速发生视网膜漏斗状全脱离为临床特征.本组8例16只眼视网膜光凝和(或)冷凝治疗后,9只眼病变完全退化或控制,占56.2%.7只眼病情未能控制,最终发展为4b至5期视网膜病变.结论 AP-ROP进展快,预后不良,部分患儿虽经严密观察和治疗,病情仍进展.视网膜光凝和(或)冷凝治疗能控制大部分AP-ROP患儿视网膜病变的发展,挽救患儿视功能.临床上需要加强观察和随访,早发现、早诊断、早治疗是减低该病致盲率的惟一方法.