Persistent visual changes following hashish consumption.

Abstract

A rare cause ofvisual loss in AIDS patients: central retinal vein occlusion vision in the right eye to only hand movement at 3 feet, but the corrected vision in the left eye was 20/30. There was no anterior segment neovascularisation and the anterior chamber angle was grade IV open. The intraocular pressures were normal in both eyes. Funduscopic examination revealed typical finding of ischaemic CRVO, which was supported by fluorescein angiography as shown in Figure 1. Laboratory investigations at the time of the diagnosis showed haemoglobin of 7-9 g/l, haematocrit of 26-4%, WBC of 800x 106/1, and platelets of 30x 101/l. Extensive coagulation investigation including antithrombin III, heparin-cofactor II and protein S, protein C, antiphospholipid antibodies, and circulating immune complexes (CIC), did not show any abnormalities.The patient was followed without treatment for 1 year, her vision remained unchanged in the left eye, but showed some improvement in the right eye; she was able to count fingers at 1 foot. Comment This is the second case in the literature of CRVO causing visual loss in a patient with AIDS. CMV retinitis remains the most common cause of loss of vision in AIDS patients.' The prognosis and the treatment of CRVO and CMV retinitis are quite different.'" The diagnosis in our patient was suspected on funduscopic examination and supported by fluorescein angiography (Fig 1). CRVO occurred in this patient in the absence of underlying cardiovascular disease or any significant coagulation defects that can lead to thrombosis.24 As in the previously reported case, our patient developed CRVO in conjunction with the treatment ofthe anaemia. In the present case, the anaemia was treated with r- HuEPO

Cannabinoid Receptor Activation Differentially Modulates Ion Channels in Photoreceptors of the Tiger Salamander

“…Numerous visual effects have been reported for marijuana and hashish consumption, many of them involving an alteration-generally enhancement-of light sensitivity (Brown 1974;Dawson et al 1977;Gregg et al 1976a,b;Hepler and Frank 1971;Hollister 1971a,b;Hollister and Gillespie 1973;Laffi and Safran 1993;Shapiro 1974). Recent description of a cannabinoid signaling system in the vertebrate retina has raised the question of whether some of these visual effects may be due to a retinal site of action.…”

Ophthalmological assessment of cannabis-induced persisting perception disorder: Is there a direct retinal effect?

“…Some case reports mention normal retinal function in patients with HPPD [5,6]; however, in none of them an extended electrophysiological evaluation was carried out. We hereby report detailed results observed in a patient, who claimed of cannabis-induced persisting perception disorder even after long period of marijuana abstinence.…”

“…It is generally recommended that patients should discontinue taking drugs and should also avoid caffeine and alcohol, which might have a negative effect on HPPD [13]. In most of the cases, HPPD disappears spontaneously, but the duration can vary between individuals: Some patients have symptoms for months, but these can also last for years [5,13]. Disturbances of visual perception following drug consumption are often unexplained, or symptoms can be misinterpreted [14].…”

“…Although short-term effects on the visual system are well known [4], there is only little information on persisting visual disturbances [5,6].…”

“…Hallucinogen persisting perception disorder (HPPD) is a temporary recurrence of disturbances in perception that are reminiscent of those experienced during one or more earlier intoxications with hallucinogens and includes many types of visual disturbances [1][2][3][4][5][6][7][8][9][10][11][12][13]. These perceptual changes can be halos around objects, difficulty in distinguishing between colors, alterations in color perception, geometric hallucinations, illusions that objects are moving or changing in size, ''visual snow,'' or floaters [8,9].…”