[Experimental study of changes in the pressure of the posterior segment of the eye under general anesthesia. Consequences for surgery of the anterior segment].
Animal studies were conducted to compare variations in intraocular (IOP) and posterior segment pressure (PSP) during general anesthesia to assess the role of PSP in the development of anesthesia for ophthalmological procedures. Anesthetic agents appear to have a marked effect on IOP during operations involving opening of hypertonic globe or examinations of children under general anesthesia, but their action on IOP has no significance during procedures requiring opening of the anterior chamber because of alteration of aqueous humor physiology. The PSP, defined as pressure in the posterior segment when the anterior segment is at atmospheric pressure, is the main factor affecting surgical conditions, a rise in PSP possibly resulting in typical complications of cataract surgery but having beneficial effects in corneal grafts for example. Posterior segment pressure cannot be studied in humans and an experimental model using rabbits under artificial ventilation following tracheotomy after general anesthesia was developed. Pressure gauges recorded arterial and central venous pressures and were connected to needles inserted in both eyes to monitor IOP and PSP, the latter from a needle passed into the anterior chamber through the cornea, which was incised over the needle to enable permanent drainage of aqueous humor. All pressures were recorded simultaneously and no correlations were observed between IOP and PSP after pentobarbitone, neosynephrine, succinylcholine, or asphyxia (interruption of ventilation and curarization). These findings suggest that IOP is not a valid measurement for assessment of anesthetic techniques, whereas PSP provides a better guideline for development of ophthalmological anesthesia.
D000768:Anesthesia, General / Q000379:methods; D000818:Animals; D002829:Choroid / Q000098:blood supply; D007429:Intraocular Pressure / Q000187:drug effects*; D008833:Microcirculation / Q000187:drug effects; D013508:Ophthalmologic Surgical Procedures; D010424:Pentobarbital / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011817:Rabbits; D012121:Respiration, Artificial; D014065:Tonometry, Ocular; D014822:Vitreous Body / Q000502:physiology
D010656:Phenylephrine; D010424:Pentobarbital
Etude expérimentale des variations de la pression du segment postérieur de l'oeil sous anesthésie générale. Conséquence pour la chirurgie du segment antérieur.