RESUMEN
PURPOSE: To investigate the effects of oral cannabinoids on retinal hemodynamics assessed by video fluorescein angiography in healthy subjects. DESIGN: Interventional study. METHODS: In a self-experiment, the cannabinoid dronabinol (delta-9-tetrahydrocannabinol [THC]) was administered orally to eight healthy medical doctors (7.5 mg Marinol; Unimed Pharmaceuticals, Chicago, Illinois, USA). At baseline and two hours after dronabinol intake, intraocular pressure (IOP) was measured and retinal hemodynamics were assessed by fluorescein angiography. The retinal arteriovenous passage time was determined on the basis of dye dilution curves by means of digital image analysis in a masked fashion. RESULTS: Dronabinol resulted in a significant IOP reduction from 13.2 +/- 1.9 mm Hg to 11.8 +/- 2.0 mm Hg (P = .038). The retinal arteriovenous passage time decreased from 1.77 +/- 0.35 seconds to 1.57 +/- 0.31 seconds (P = .028). Systemic blood pressure and heart rate were not statistically significantly altered. CONCLUSIONS: Cannabinoids, already known for their ability to reduce IOP, may result in increased retinal hemodynamics. This may be beneficial in ocular circulatory disorders, including glaucoma.
Asunto(s)
Dronabinol/administración & dosificación , Psicotrópicos/administración & dosificación , Vasos Retinianos/fisiología , Administración Oral , Adulto , Circulación Sanguínea/efectos de los fármacos , Presión Sanguínea , Femenino , Angiografía con Fluoresceína , Frecuencia Cardíaca , Humanos , Presión Intraocular/fisiología , Masculino , Estudios Prospectivos , Tonometría OcularRESUMEN
BACKGROUND: Our aim was to identify different states of energy metabolism in the perfused isolated vertebrate retina by simultaneous recordings of light-evoked changes of transretinal potential (TRP) and spectroscopic changes related to oxidation of pyridine nucleotides. METHODS: Isolated retinas were obtained from R.esc. and superfused. For each setting, three experiments were performed. Eighteen retinas were used. TRP as a response to light stimulation was recorded simultaneously with stimulus-induced transmission shift at 350 nm. These responses were recorded under normal conditions, under withdrawal of oxygen and glucose, and after addition of electron transport inhibitors and uncouplers of oxidative phosphorylation. RESULTS: Under normal conditions, TRP was strongly correlated with transmission shift after light stimulation. Without oxygen, amplitudes of stimulus-related TRP decreased and response related increase of transmission at 350 nm was reduced. The retina showed a much higher general absorption of the analyzing light. During glucose lack, an overall increase in transmission at 350 nm could be observed. The addition of Amytal yielded a specific reduction of the OFF components. Cyanide attenuated the ON and OFF components. Dinitrophenol yielded a considerable loss of the electrical ON response. Transmission change was affected less than electrical signal. Chlorophenylhydrazine induced a reproducible reduction of electrical responses, with a relative increase of transmission shift at 350 nm. CONCLUSION: In the isolated perfused retina, different states of energy metabolism and their specific impact on neuroretinal responses can be examined by simultaneous recordings of stimulus-related neuronal activity and spectroscopic changes.
Asunto(s)
Metabolismo Energético/fisiología , Retina/metabolismo , Retina/efectos de la radiación , Rayos Ultravioleta , Amobarbital/farmacología , Animales , Transporte de Electrón/efectos de los fármacos , Electrorretinografía , Glucosa/fisiología , Hipoxia/metabolismo , Luz , Potenciales de la Membrana , Oxidación-Reducción , Fosforilación Oxidativa , Rana esculenta , Cianuro de Sodio/farmacología , Desacopladores/farmacologíaRESUMEN
PURPOSE: To analyze the occurrence of near infrared (NIR) fluorescence in relation to NIR reflectance, blue-light-excited autofluorescence, angiograms, and funduscopy. METHODS: Observational consecutive case series in patients with macular diseases. Imaging was performed with a confocal scanning laser ophthalmoscope for NIR reflectance, blue-light-excited autofluorescence, NIR fluorescence, and fluorescein and indocyanine green (ICG) angiograms. In cases in which NIR fluorescence was observed, five to nine images were averaged. The leakage of the scanning laser ophthalmoscope was analyzed. RESULTS: In the 291 eyes analyzed, NIR fluorescence was observed in 51 and was graded weak in 27 with wet age-related macular degeneration (AMD, 10 cases), dry AMD with pigment clumping (n=7), chronic central serous choroidopathy (CSC; n=5), choroidal nevi (n=2), subretinal hemorrhages (n=2), and chloroquine maculopathy (n=1). Strong NIR fluorescence was found in 24 eyes, with wet AMD (n=14), subretinal hemorrhages (n=8), and choroidal nevi (n=2). Except for four eyes, we observed a strong correlation of NIR fluorescence and increased NIR reflectance at identical fundus location (92.2%). NIR fluorescence corresponded with increased blue-light-excited autofluorescence in 21 of 31 patients with AMD and in 4 of 5 patients with chronic CSC, but in none of the 4 patients with nevi. Funduscopy showed that structures with NIR fluorescence were pigmented or consisted of degraded blood. Barrier filter leakage of the imaging system was 6.2x10(-6). CONCLUSIONS: The high correlation of NIR fluorescence and reflectance indicated that part of the observed NIR fluorescence is pseudofluorescence, whereas gray-scale analysis indicated that both NIR autofluorescence and pseudofluorescence contribute to the NIR fluorescence images. Quantification of leakage of the imaging system indicated a significant part of the observed NIR fluorescence is NIR autofluorescence. As NIR fluorescence derives from pigmented lesions, melanin is a possible source if NIR reflectance is also increased. Comparison with blue-light-excited autofluorescence showed differences between AMD and patients with nevi. NIR autofluorescence was also detected in single cases of maculopathy without corresponding NIR reflectance.