Intereye comparison of ocular factors in normal tension glaucoma with asymmetric visual field loss in Korean population

PurposeTo identify ocular parameters corresponding to asymmetric visual field (VF) loss in normal tension glaucoma (NTG) through intereye comparisons.Patients and methodsMedical records of NTG patients with asymmetric and symmetric VF losses were retrospectively reviewed. The criterion for asymmetry in VF was 6 dB difference of mean deviation. Refractive error, intraocular pressure (IOP), central corneal thickness, ovality index, and peripapillary atrophy (PPA)/disc area ratio were obtained from each patient. Intereye comparison was performed for asymmetric group, symmetric group, and myopic and nonmyopic asymmetric subgroups.ResultsWe included 155 patients; 110 patients in asymmetric group and 45 patients in symmetric group. In intereye comparison for total asymmetric group, refractive error (P = 0.006), initial IOP (P = 0.001), ovality index (P = 0.008), and PPA (P P = 0.004), ovality index (P = 0.001), and PPA (P = 0.003) were significant factors. For nonmyopic subgroup, initial IOP (P = 0.003) and PPA (P = 0.007) were significant factors. Symmetric group showed no significant difference between the eyes. Multivariate analysis demonstrated that refractive error (P = 0.002) and PPA (P = 0.028) were significant factors in myopic subgroup, and initial IOP (P = 0.022) and PPA (P = 0.002) were significant factors in nonmyopic subgroup.ConclusionsIn this intereye comparison, the more myopic eye in myopic NTG patient, and the more pressured eye in nonmyopic NTG patient demonstrated more severe VF loss. Myopic and nonmyopic patients may follow different pathophysiologic processes. Discriminative attentions should be paid to NTG patients by subtypes.研究目的：通过双眼对比分析，识别与正常眼压性青光眼（Normal Tension Glaucoma, NTG）患者不对称性视野（Visual Field, VF）丢失相关的眼部参数。 研究对象与方法：回顾性分析存在不对称及对称性视野丢失的正常眼压性青光眼患者的临床病历资料。视野不对称的判定标准为双眼平均偏差差值达6 dB。收集所有患者的屈光不正度数、眼压（Intraocular Pressure, IOP）、中央角膜厚度、椭圆指数以及视盘周围萎缩（Peripapillary Atrophy, PPA）/视盘面积比值。分别对不对称组、对称组，以及近视与非近视不对称亚组开展双眼对比研究。 研究结果：本研究共纳入155例患者，其中不对称组110例，对称组45例。针对整体不对称组的双眼对比分析显示，屈光不正度数（P=0.006）、初始眼压（P=0.001）、椭圆指数（P=0.008）及视盘周围萎缩（P=0.004）为显著相关因素；近视不对称亚组分析显示，椭圆指数（P=0.001）与视盘周围萎缩（P=0.003）为显著影响因素。非近视亚组中，初始眼压（P=0.003）与视盘周围萎缩（P=0.007）为显著相关因素。对称组双眼间未观察到显著差异。多因素分析结果表明，在近视亚组中，屈光不正度数（P=0.002）与视盘周围萎缩（P=0.028）为独立显著影响因素；在非近视亚组中，初始眼压（P=0.022）与视盘周围萎缩（P=0.002）为独立显著影响因素。 研究结论：本项双眼对比研究显示，在近视型正常眼压性青光眼患者中，近视程度更高的患眼视野丢失更为严重；而非近视型患者中，眼压水平更高的患眼视野丢失更显著。近视与非近视患者的病理生理过程可能存在差异，临床需针对不同亚型的正常眼压性青光眼患者予以差异化关注。