Zobor Ditta, Strasser Torsten, Zobor Gergely, Schober Franziska, Messias Andre, Strauss Olaf, Batra Anil, Zrenner Eberhart
Institute for Ophthalmic Research, University of Tübingen, Schleichstr 12-16, 72076, Tübingen, Germany,
Doc Ophthalmol. 2015 Apr;130(2):121-30. doi: 10.1007/s10633-015-9481-2. Epub 2015 Jan 23.
Cannabis is a psychotomimetic agent that induces impairment of sensory perception. We present detailed clinical and electrophysiological data of patients with hallucinogen persisting perception disorder (HPPD) after marijuana consumption.
A HPPD patient and four heavy cannabis smokers with no visual disturbances (controls) underwent complete ophthalmological examination including psychophysical tests (visual acuity, color vision, visual field, and dark adaptation) and detailed electrophysiological examinations, including extended Ganzfeld ERG, multifocal ERG, and electrooculography (EOG). Furthermore, electrically evoked phosphene thresholds (EPTs) were measured to further evaluate retinal function.
Ophthalmological and most electrophysiological examinations were within normal limits for the HPPD patient and for all control subjects. Interestingly, EOG results of the HPPD patient showed a slightly reduced fast oscillation ratio, diminished standing potentials of the slow oscillations, and a light peak within normal range resulting in higher Arden ratios. The EPTs of the patient were reduced, in particular for pulses with long durations (50 ms) causing visual sensations even at lowest possible currents of the neurostimulator. The control subjects did not reveal such alterations.
Our findings suggest a direct effect of cannabinoids on the retina and retinal pigment epithelium function, which may be involved in disturbances of the visual function experienced after drug consumption. The observations presented here may contribute to the elucidation of the detailed mechanism. Furthermore, EOG and EPT measurements may be useful tools to demonstrate long-term retinal alterations in cannabis-induced HPPD in patients.
大麻是一种致幻剂，可导致感觉知觉受损。我们展示了吸食大麻后致幻剂持续性感知障碍（HPPD）患者的详细临床和电生理数据。
一名HPPD患者和四名无视觉障碍的重度大麻吸烟者（对照组）接受了全面的眼科检查，包括心理物理学测试（视力、色觉、视野和暗适应）以及详细的电生理检查，包括扩展全视野视网膜电图（ERG）、多焦ERG和眼电图（EOG）。此外，测量了电诱发光幻视阈值（EPT）以进一步评估视网膜功能。
HPPD患者和所有对照受试者的眼科及大多数电生理检查均在正常范围内。有趣的是，HPPD患者的EOG结果显示快振荡比率略有降低，慢振荡的静息电位减弱，光峰在正常范围内，导致Arden比率升高。患者的EPT降低，特别是对于持续时间长（50毫秒）的脉冲，即使在神经刺激器的最低可能电流下也会引起视觉感觉。对照受试者未发现此类改变。
我们的研究结果表明大麻素对视网膜和视网膜色素上皮功能有直接影响，这可能与药物摄入后出现的视觉功能障碍有关。此处呈现的观察结果可能有助于阐明详细机制。此外，EOG和EPT测量可能是证明大麻诱导的HPPD患者长期视网膜改变的有用工具。
