- Email: [email protected]
Studies on retinal acid-base behaviour with glass pH sensitive microelectrode in the intact mammalian eye
9Y3
ABSTRACTS
higher at the beginning, later significantly lower, than those of controls. Towards the end of the test period values were approximately the same in both groups. A significant decrease of artivity (compared to controls) could only be found with SDH and especially with GOT.
The Ophthalmic ,J. STEPANIK,
Artery-Tonography
F’ienna
Based on investigations performed within the past few years a new equipment was developed which records the intraocular pressure at the time of biomicroscopically observed collapse phenomenon of the central retinal artery on the disc. It consists of a pressure-sensitive probe (specially developed for this purpose) which, built into a contact lens and adapted to the patient’s eye, allows exact observation of the optic disc on the slit lamp, whilst the foot plate of the probe perceives the intraocular pressure through the cornea. The output of the probe is transferred by an electronic device to a 100 mm recording strip. The standard deviation of a single measurement as derived from 12 readings on the diastolic pressure level of the same eye is impressively small : S.D. = *1.5 mmHg. Clinical results achieved by this equipment will be demonstrated and discussed.
Studies on Retinal Acid-Base Mammalian Eye 11. TSACOPCKLOS
AND
S. LEVY,
Behaviour
with Glass pH Sensitive Microelectrode
in the Intact
Genera
The development of pH microelectrodes (1 pm tip diameter) and of a micromanipulatorillumination system for their safe introduction into the intact eye has made possible the investigation of retinal interstitial (cellular) and preretinal vitreous (extracellular) acid-base status. The following resuhs were obtained: (1) The retinal pH was 7.23 and vibreous pH 7.32; both are more acidic than plasma or aqueous humour pH. (2) Arterial PCO, (PaCO,) changes affect both retinal and vitreous pH but the time response t,o CO, in vitreous was much slower t’han in the inner retina. (3) Neither sodium bicarbonate (NaHCO,) nor NH&l injected intravenously affect retinal or pm-retinal vitreous pH because t,hey do not cross the blood-retina.1 barrier. (4) Acetazolamide (50 mg/kg) provoked retinal acidosis in relation to the increase of PaCO,. (5) Systemic< hypoxia provoked a marked retinal acidosis, presumably because of the lactic acid accumulation in the retina under this condition. Based on retinal and pre-retinal vitreous acid-base behaviour and prior blood flow data. a working hypothesis on the metabolic regulat)ion of retinal blood flow is briefly discussed.
Cineangiographic D. \2'. HILL
Inflow Studies of the Retina
AND L. LAATIKAINEK.
Lowion
-1 modified Zeiss fundus camera (exhibit) indocyanine green (ICG) given by regional Background studies show:
has been used arterial injection
to record the in the pat.
inflow
(1) Variable bolus profiles determined by external factors. (2) Only a peripheral annulus of fluorescein is visible in the larger arterioles, strat,es faster axial inflow. (3) Inflow shows a slight increase during the systolic phase of the pulse with is a phase difference, ICG leading. These points will be illustrated by a tine film and quantitative data. Studies of regional inflow in concentric zones around the disc show:
of fluorescein
but both
ICG dyes.
or
demonthere
(I) Progressive decrease of linear inflow rate along arterioles from disc to periphery; branches of similar calibre showing slower inflow peripherally. (2) Arterioles with similar volume inflow supply much smaller retinal areas around the disc than peripherally. (3) Dye passage from precapillary arteriole to collect,or venule is also slower in the periphery.
ABSTRACTS
higher at the beginning, later significantly lower, than those of controls. Towards the end of the test period values were approximately the same in both groups. A significant decrease of artivity (compared to controls) could only be found with SDH and especially with GOT.
The Ophthalmic ,J. STEPANIK,
Artery-Tonography
F’ienna
Based on investigations performed within the past few years a new equipment was developed which records the intraocular pressure at the time of biomicroscopically observed collapse phenomenon of the central retinal artery on the disc. It consists of a pressure-sensitive probe (specially developed for this purpose) which, built into a contact lens and adapted to the patient’s eye, allows exact observation of the optic disc on the slit lamp, whilst the foot plate of the probe perceives the intraocular pressure through the cornea. The output of the probe is transferred by an electronic device to a 100 mm recording strip. The standard deviation of a single measurement as derived from 12 readings on the diastolic pressure level of the same eye is impressively small : S.D. = *1.5 mmHg. Clinical results achieved by this equipment will be demonstrated and discussed.
Studies on Retinal Acid-Base Mammalian Eye 11. TSACOPCKLOS
AND
S. LEVY,
Behaviour
with Glass pH Sensitive Microelectrode
in the Intact
Genera
The development of pH microelectrodes (1 pm tip diameter) and of a micromanipulatorillumination system for their safe introduction into the intact eye has made possible the investigation of retinal interstitial (cellular) and preretinal vitreous (extracellular) acid-base status. The following resuhs were obtained: (1) The retinal pH was 7.23 and vibreous pH 7.32; both are more acidic than plasma or aqueous humour pH. (2) Arterial PCO, (PaCO,) changes affect both retinal and vitreous pH but the time response t,o CO, in vitreous was much slower t’han in the inner retina. (3) Neither sodium bicarbonate (NaHCO,) nor NH&l injected intravenously affect retinal or pm-retinal vitreous pH because t,hey do not cross the blood-retina.1 barrier. (4) Acetazolamide (50 mg/kg) provoked retinal acidosis in relation to the increase of PaCO,. (5) Systemic< hypoxia provoked a marked retinal acidosis, presumably because of the lactic acid accumulation in the retina under this condition. Based on retinal and pre-retinal vitreous acid-base behaviour and prior blood flow data. a working hypothesis on the metabolic regulat)ion of retinal blood flow is briefly discussed.
Cineangiographic D. \2'. HILL
Inflow Studies of the Retina
AND L. LAATIKAINEK.
Lowion
-1 modified Zeiss fundus camera (exhibit) indocyanine green (ICG) given by regional Background studies show:
has been used arterial injection
to record the in the pat.
inflow
(1) Variable bolus profiles determined by external factors. (2) Only a peripheral annulus of fluorescein is visible in the larger arterioles, strat,es faster axial inflow. (3) Inflow shows a slight increase during the systolic phase of the pulse with is a phase difference, ICG leading. These points will be illustrated by a tine film and quantitative data. Studies of regional inflow in concentric zones around the disc show:
of fluorescein
but both
ICG dyes.
or
demonthere
(I) Progressive decrease of linear inflow rate along arterioles from disc to periphery; branches of similar calibre showing slower inflow peripherally. (2) Arterioles with similar volume inflow supply much smaller retinal areas around the disc than peripherally. (3) Dye passage from precapillary arteriole to collect,or venule is also slower in the periphery.