Kim Dong Myung, Seo Je Hyun, Kim Seok Hwan, Hwang Seung-Sik
Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea.
J Glaucoma. 2007 May;16(3):293-6. doi: 10.1097/IJG.0b013e31803bda3d.
To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients.
Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of <or=15 mm Hg (group A) and a high-teen group had lowest IOP of >15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups.
Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07).
Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.
比较正常眼压性青光眼（NTG）患者中低青少年眼压组和高青少年眼压组局限性视网膜神经纤维层（RNFL）缺损的特征。
本研究选取了77例NTG患者的77只眼，这些患者在初次就诊于青光眼专科医生时，RNFL照片显示有局限性RNFL缺损且伴有相应的视野缺损。纳入双眼日间眼压范围在低青少年或高青少年的患者。所有参与者均完成了验光、日间眼压测量、中央角膜厚度（CCT）测量、立体视盘照相、RNFL照相和自动视野检查。在RNFL照片上，测量缺损与黄斑的接近程度（α角）和缺损宽度（β角）以代表RNFL缺损。根据眼压水平将患者分为2组。低青少年组最高眼压≤15 mmHg（A组），高青少年组最低眼压>15 mmHg（B组）。比较两组之间的诊断年龄、男性患者百分比、全身疾病、验光、CCT、最高眼压、α角、β角以及视野的平均偏差和模式标准偏差。
两组之间NTG的诊断年龄、年龄分布、男性患者百分比、全身疾病、等效球镜度、CCT、平均偏差和模式标准偏差无差异。A组最高眼压为13.8±1.2 mmHg，B组为19.2±1.4 mmHg（P<0.001）。A组的α角明显小于B组（37.0±14.0对56.5±21.2度，P<0.001），而两组之间的β角无差异（39.9±17.9对37.5±15.9度，P=0.54）。等效球镜度与α角之间（r=-0.03，P=0.82）、等效球镜度与β角之间（r=-0.04，P=0.74）以及α角与β角之间（r=-0.21，P=0.07）均无显著相关性。
A组局限性RNFL缺损比B组更靠近黄斑中心，而两组之间的缺损宽度无差异。这些发现提供了间接证据，表明NTG中RNFL缺损的发生可能存在多种致病机制。
