Mechanism of the Formation of X-Ray-Induced Phosphenes: I. Electrophysiological Investigations

Doly, M.; Isabelle, Didier B.; Vincent, Patrick; Gaillard, G; Meyniel, G

doi:10.2307/3575240

Cited by 22 publications

(10 citation statements)

References 25 publications

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“…Phosphenes can result from a photochemical breakdown in the rods and cones by Photons X and Gamma [ 63 , 64 ] and there is a relation between amplitude on the electroretinogram and surface of exposed retina [ 65 , 66 ]. The importance of photopigment bleaching has also been linked to energy transfer from the opsin to the attachment site of the chromophoric group [ 65 , 66 ]. Patients undergoing ocular proton therapy experience colored phosphenes that correlate with proximity to the macula and exhibit strikingly blue predominance in a mesopic ambience.…”

Section: Mechanisms Of Phosphenesmentioning

confidence: 99%

Mechanisms of phosphenes in irradiated patients

et al. 2017

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Anomalous visual perceptions have been reported in various diseases of the retina and visual pathways or can be experienced under specific conditions in healthy individuals. Phosphenes are perceptions of light in the absence of ambient light, occurring independently of the physiological and classical photonic stimulation of the retina. They are a frequent symptom in patients irradiated in the region of the central nervous system (CNS), head and neck and the eyes. Phosphenes have historically been attributed to complex physical phenomena such as Cherenkov radiation. While phosphenes are related to Cherenkov radiation under high energy photon/electron irradiation conditions, physical phenomena are unlikely to be responsible for light flashes at energies used for ocular proton therapy. Phosphenes may involve a direct role for ocular photoreceptors and possible interactions between cones and rods. Other mechanisms involving the retinal ganglion cells or ultraweak biophoton emission and rhodopsin bleaching after exposure to free radicals are also likely to be involved. Despite their frequency as shown in our preliminary observations, phosphenes have been underreported probably because their mechanism and impact are poorly understood. Recently, phosphenes have been used to restore the vision and whether they might predict vision loss after therapeutic irradiation is a current field of investigation. We have reviewed and also investigated here the mechanisms related to the occurrence of phosphenes in irradiated patients and especially in patients irradiated by proton therapy for ocular tumors.

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Section: Mechanisms Of Phosphenesmentioning

confidence: 99%

Mechanisms of phosphenes in irradiated patients

et al. 2017

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“…The curves obtained by tracing the ERG amplitude as a function of time -known as survival curves -all have the same general trend [5] the survival conditions; then, there is an equilibrium phase during which the amplitude of the b wave varies little, fol lowed finally by a progressive decrease in amplitude indicating the end of survival (b wave < 10 pV). For this reason induction of lipid peroxidation was not started until the retina had reached its stationary phaseapproximatively 1 h after the beginning of the perfusion.…”

Section: Resultsmentioning

confidence: 99%

“…In the perfusion liquid the retina was prog ressively detached from the retinal epithelium and finally freed by cutting the optical nerve. The retina was then mounted as a membrane in a perfusion cell described in a previous paper [5]. The perfusion liquid had the following composition: NaCl, 121.5 mAf; KC1, 3.1 mAf; CaCL.…”

Section: Methodsmentioning

confidence: 99%

Effects of Lipid Peroxidation on the Isolated Rat Retina

et al. 1984

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The effects of membrane lipid peroxidation are determined in isolated albino rat retina. Lipoperoxidation induced by addition of Fe²⁺ + ascorbate to the perfusion liquid leads to an irreversible decrease of amplitude in the electroretinogram. The experimental model proposed here provides the possibility to monitor the survival of the retina and demonstrates that ocular lipid peroxidation very notably shortens the survival time. The specific role of the rod membranes for the excitation mechanism in the retina as revealed by these experiments is discussed.

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“…The retina, composed essentially of rods, gives a purely scotopic ERG. After two hours of dark adaptation, the rat was sacrificed by cervical dislocation, and the retina was dissected out and mounted as a membrane in a perfusion system as described previously (4). The solution was constantly bubbled with a mixture of 95% 02and 5% C02 and maintained at 37°C.…”

Section: Ex Vivo Model Of Retinal Ischemia By Interruption Of Perfusionmentioning

confidence: 99%

Experimental Electroretinographic Exploration of Retinal Ischemia: Preventive Use of Free Radical Scavengers and Anti-PAF Agents

Cluzel²,

Mt³

et al. 1997

Journal of Ocular Pharmacology and Therapeutics

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Electroretinographic exploration is an effective approach to evaluate retinal function. In order to investigate physiopathological mechanisms and evaluate potentially protective therapies for retinal ischemia, we developed three experimental models: the first two on isolated retina, with ischemia induced by either stopping perfusion or clamping the ophthalmic artery, and the third, in vivo, with ischemia induced by ocular hypertonia. Since free radicals are implicated in the formation of postischemic lesions, we evaluated the protective effects of drugs known to be free radical scavengers and of an immunomediator antagonist, an anti-PAF (platelet activating factor) agent.

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Mechanism of the Formation of X-Ray-Induced Phosphenes: I. Electrophysiological Investigations

Cited by 22 publications

References 25 publications

Mechanisms of phosphenes in irradiated patients

Mechanisms of phosphenes in irradiated patients

Effects of Lipid Peroxidation on the Isolated Rat Retina

Experimental Electroretinographic Exploration of Retinal Ischemia: Preventive Use of Free Radical Scavengers and Anti-PAF Agents

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