Vajaranant Thasarat S, Fishman Gerald A, Szlyk Janet P, Grant-Jordan Patricia, Lindeman Marty, Seiple William
Department of Ophthalmology and Visual Science, University of Illinois at Chicago, Chicago, Illinois 60612, USA.
Ophthalmology. 2008 Apr;115(4):723-9. doi: 10.1016/j.ophtha.2007.07.032. Epub 2008 Jan 16.
To test whether choroideremia carriers have a mosaic pattern of retinal dysfunction, as noted in carriers of X-linked recessive retinitis pigmentosa and X-linked retinoschisis.
Prospective observational case series.
Seven obligate choroideremia carriers (age range, 18-72) with visual acuity (VA) of 20/25 or better were recruited into the study.
The carriers underwent VA testing (Snellen chart), ophthalmic examination, Humphrey visual field (VF), and multifocal electroretinographic testing. The amplitude and implicit time scales were measured by the algorithm of Hood and Li. The amplitude measures (a scales) and implicit time measures (t scales) were reported abnormal when they were >2 standard deviations above the mean of age-similar normally sighted control subjects.
Mapping of local 103 electroretinographic response amplitudes and implicit times.
Only 1 of the 7 carriers showed abnormal Humphrey VF thresholds, whereas 6 of the 7 carriers showed a mosaic pattern of retinal dysfunction measured by multifocal electroretinographic testing. All 6 carriers showed statistically significant implicit time delays, whereas 4 carriers showed statistically significant amplitude reductions and implicit time delays (P<0.05 to P<0.0006). One carrier with a normal-appearing macula and normal Humphrey VF showed a cluster of statistically significant implicit time delays within the macula (P<0.05 to P<0.0006). The overall extent of local electroretinographic abnormalities corresponded to the severity of ophthalmoscopically apparent pigmentary changes. The one carrier with mild threshold elevation on Humphrey VF testing showed the most ophthalmoscopically apparent extensive fundus pigmentary changes.
We demonstrated a mosaic pattern of retinal cone dysfunction in carriers of choroideremia. Our findings are consistent with the Lyon hypothesis of random X-chromosome inactivation. Multifocal electroretinographic testing is potentially sensitive to detect local retinal dysfunction in choroideremia carriers even in those with a normal-appearing macula and good VA.
检测无脉络膜症携带者是否具有视网膜功能障碍的镶嵌模式，正如在X连锁隐性视网膜色素变性和X连锁视网膜劈裂症携带者中所观察到的那样。
前瞻性观察病例系列。
招募了7名视力（VA）为20/25或更好的无脉络膜症携带者（年龄范围18 - 72岁）参与本研究。
携带者接受了视力测试（斯内伦视力表）、眼科检查、汉弗莱视野（VF）检查和多焦视网膜电图测试。振幅和隐含时间尺度通过胡德和李的算法进行测量。当振幅测量值（a尺度）和隐含时间测量值（t尺度）高于年龄匹配的正常视力对照受试者平均值2个标准差以上时，报告为异常。
绘制局部103个视网膜电图反应振幅和隐含时间图。
7名携带者中只有1名显示汉弗莱视野阈值异常，而7名携带者中有6名通过多焦视网膜电图测试显示出视网膜功能障碍的镶嵌模式。所有6名携带者均显示出具有统计学意义的隐含时间延迟，而4名携带者显示出具有统计学意义的振幅降低和隐含时间延迟（P<0.05至P<0.0006）。一名黄斑外观正常且汉弗莱视野正常的携带者在黄斑区内显示出一组具有统计学意义的隐含时间延迟（P<0.05至P<0.0006）。局部视网膜电图异常的总体范围与眼底镜下明显的色素变化程度相对应。在汉弗莱视野测试中阈值轻度升高的那名携带者眼底色素变化在眼底镜下最为明显且范围广泛。
我们在无脉络膜症携带者中证实了视网膜锥体细胞功能障碍的镶嵌模式。我们的发现与随机X染色体失活的莱昂假说一致。即使在黄斑外观正常且视力良好的无脉络膜症携带者中，多焦视网膜电图测试对于检测局部视网膜功能障碍可能也很敏感。
