目的：不同距离观看3D影像后调节幅度、集合近点(NPC)及近隐斜视和视力疲劳的症状分析。

方法：前瞻性研究，包括30例青年。每人每天三次分别在特定距离和不同距离观看3D影像，并连续三天进行观察，每一距离使用相同视频，相同的时间和不同的屏幕大小。使用 K-multimedia player 3D播放器。观看3D影响后立即记录立体视觉、调节幅度、调节近点及近隐斜视和视力疲劳症状等相关变量。分别使用TNO测量视功能，RAF尺测量调节幅度和集合近点，棱镜杆测量近隐斜视，封闭式问卷调查视力疲劳症状的发生情况。用描述性统计和配对t检验进行数据分析，定性数据采用卡方检测。

结果：在40 cm，3 m和6 m处调节幅度分别减少了0.66 D，1.12 D和1.44 D，集合近点显著降低了0.63 cm，0.93 cm和1.23 cm，近隐斜视分别增加了0.87，2.74和2.2棱镜度。结果发现，大多数受试者在每一距离处都出现眼周疼痛，头痛和刺激等反应。在家庭环境中，头痛、盗汗、疲劳、刺激和恶心等症状会显著增加，此外，通过使用笔记本电脑观看3D可能会引起头痛和盗汗等相关不适症状。

结论：观看3D前后、在三种不同距离处，调节幅度、集合近点及近隐斜视和视力疲劳的症状显著不同。在不同距离观看3D影像后，视力疲劳为主要症状。

METHODS: A prospective study. Thirty young adults were randomly selected. Each individual was exposed to 3D viewing thrice in a day for a fixed distance and the distance was varied on three consecutive days. Same video of equal duration and different screen sizes were used for every distance. Cyclic 3D mode of K-multimedia(KM)player was used for projecting the 3D video. Different variables like stereopsis, amplitude of accommodation, near point of accommodation, near phoria and asthenopic symptoms were recorded immediately after 3D video viewing. Stereopsis was measured with “Toegepast Natuurwetenschappelijk Onderzoek” or “Netherlands Organisation for Applied Scientific Research”(TNO test), amplitude of accommodation and NPC were measured using RAF ruler, near phoria was measured using prism bar and a closed ended sample questionnaire was used to know the occurrence of asthenopic symptoms. Statistical analyses were performed using descriptive statistics, paired t-test etc. Qualitative data was analyzed using Chi-square test.

RESULTS: For every distance of 40 cm, 3 m and 6 m, amplitude of accommodation was significantly reduced by 0.66 D, 1.12 D and 1.44 D. NPC got significantly receded by 0.63 cm, 0.93 cm and 1.23 cm, and the near phoria was significantly increased by 0.87, and 2.2 prism dioptres(PD)base-in respectively. It was found that most of the subjects got pain around the eyes, headache and irritation for each viewing distance. This study also revealed that 3D video viewing in theaters may increase the symptoms of headache, watering and irritation. Symptoms like headache, watering, fatigue, irritation and nausea may increase considerably at home environment and symptoms such as headache and watering may cause significant discomfort by 3D viewing using a laptop.

CONCLUSION: There was a significant difference in amplitude of accommodation, NPC, near phoria and asthenopic symptoms before and after viewing a 3D video and also at three viewing distances. There was a predominant occurrence of asthenopic symptoms after 3D video viewing at different distances.