Purpose: To report vitreous oxygen tension before, immediately after, and at longer times after vitrectomy. Design: A prospective, interventional consecutive case series. Methods: Oxygen was measured using an optical ...Purpose: To report vitreous oxygen tension before, immediately after, and at longer times after vitrectomy. Design: A prospective, interventional consecutive case series. Methods: Oxygen was measured using an optical oxygen sensor in patients undergoing vitrectomy. Intraoperatively, oxygen measurements were taken before and after vitrectomy in two intraocular locations: adjacent to the lens and in the mid- vitreous. Results: Sixty- nine eyes underwent oxygen tension measurements at the time of vitrectomy. In baseline eyes, oxygen tension in the vitreous was low, measuring 8.7± 0.6 mm Hg adjacent to the lens and 7.1± 0.5 mm Hg in the mid- vitreous. The difference between the two locations was statistically significant (P< .003), indicating that vitreous gel maintains an intraocular oxygen gradient. Immediately after vitrectomy, oxygen tension in the fluid- filled eye was higher, measuring 69.6± 4.8 mm Hg adjacent to the lens and 75.6± 4.1 mm Hg in the mid- vitreous. There was no statistically significant oxygen gradient between the two locations. The difference in oxygen tension pre- and postvitrectomy is highly statistically signifi- cant (P < .0001 lens, P < .0001 mid- vitreous). In eyes with a history of vitrectomy and previous removal of the vitreous gel, the intraocular oxygen tension was significantly higher than in eyes with a formed vitreous gel undergoing a first vitrectomy (P< .02 lens, P< .003 mid- vitreous).Conclusion: Vitrectomy surgery significantly increases intraocular oxygen tension during and for prolonged periods after surgery. This exposes the crystalline lens to abnormally high oxygen and may lead to nuclear cataract formation.展开更多
Purpose: To evaluate the correlations between office- hour intraocular pressures (IOP) and peak nocturnal IOP in healthy and glaucomatous eyes. Design: Retrospective review of laboratory records. Methods: We reviewed ...Purpose: To evaluate the correlations between office- hour intraocular pressures (IOP) and peak nocturnal IOP in healthy and glaucomatous eyes. Design: Retrospective review of laboratory records. Methods: We reviewed 24- hour data of IOP collected from 33 younger healthy subjects (aged 18 to 25 years), 35 older healthy subjects (aged40 to 74 years), and 35 untreated older glaucoma patients (aged40 to 79 years) housed in a sleep laboratory. Measurements of IOP were taken every 2 hours using a pneumatonometer in the sitting and supine positions during the diurnal/wake period (7 am to 11 pm) and in the supine position during the nocturnal/sleep period. Correlations between average sitting or supine IOP in the right eye between 9:30 am and 3:30 pm (office hours) and peak right eye IOP during the nocturnal hours were analyzed. Results: The average values of supine IOP during office hours were found to have the strongest correlation with peak nocturnal IOP in older glaucoma subjects (r=.713, P < .001), whereas the correlation was less in older healthy subjects (r =.523, P< .01) and was absent in younger healthy subjects (r=.224, P=.21). The correlation between average sitting IOP values during office hours and peak nocturnal IOP was also strong in older glaucoma subjects (r=.601, P< .001) and moderate in older healthy subjects (r=.412, P< .05), but absent in younger healthy subjects (r=- .077, P=.672). Conclusion: Using a modification of the diurnal IOP curve, the magnitude of peak nocturnal IOP in untreated glaucoma patients can be estimated during routine office visits. Supine IOP measurements estimate peak nocturnal IOP better than sitting measurements. This estimation may provide the clinician with valuable information regarding the nocturnal IOP peak in glaucoma patients.展开更多
文摘Purpose: To report vitreous oxygen tension before, immediately after, and at longer times after vitrectomy. Design: A prospective, interventional consecutive case series. Methods: Oxygen was measured using an optical oxygen sensor in patients undergoing vitrectomy. Intraoperatively, oxygen measurements were taken before and after vitrectomy in two intraocular locations: adjacent to the lens and in the mid- vitreous. Results: Sixty- nine eyes underwent oxygen tension measurements at the time of vitrectomy. In baseline eyes, oxygen tension in the vitreous was low, measuring 8.7± 0.6 mm Hg adjacent to the lens and 7.1± 0.5 mm Hg in the mid- vitreous. The difference between the two locations was statistically significant (P< .003), indicating that vitreous gel maintains an intraocular oxygen gradient. Immediately after vitrectomy, oxygen tension in the fluid- filled eye was higher, measuring 69.6± 4.8 mm Hg adjacent to the lens and 75.6± 4.1 mm Hg in the mid- vitreous. There was no statistically significant oxygen gradient between the two locations. The difference in oxygen tension pre- and postvitrectomy is highly statistically signifi- cant (P < .0001 lens, P < .0001 mid- vitreous). In eyes with a history of vitrectomy and previous removal of the vitreous gel, the intraocular oxygen tension was significantly higher than in eyes with a formed vitreous gel undergoing a first vitrectomy (P< .02 lens, P< .003 mid- vitreous).Conclusion: Vitrectomy surgery significantly increases intraocular oxygen tension during and for prolonged periods after surgery. This exposes the crystalline lens to abnormally high oxygen and may lead to nuclear cataract formation.
文摘Purpose: To evaluate the correlations between office- hour intraocular pressures (IOP) and peak nocturnal IOP in healthy and glaucomatous eyes. Design: Retrospective review of laboratory records. Methods: We reviewed 24- hour data of IOP collected from 33 younger healthy subjects (aged 18 to 25 years), 35 older healthy subjects (aged40 to 74 years), and 35 untreated older glaucoma patients (aged40 to 79 years) housed in a sleep laboratory. Measurements of IOP were taken every 2 hours using a pneumatonometer in the sitting and supine positions during the diurnal/wake period (7 am to 11 pm) and in the supine position during the nocturnal/sleep period. Correlations between average sitting or supine IOP in the right eye between 9:30 am and 3:30 pm (office hours) and peak right eye IOP during the nocturnal hours were analyzed. Results: The average values of supine IOP during office hours were found to have the strongest correlation with peak nocturnal IOP in older glaucoma subjects (r=.713, P < .001), whereas the correlation was less in older healthy subjects (r =.523, P< .01) and was absent in younger healthy subjects (r=.224, P=.21). The correlation between average sitting IOP values during office hours and peak nocturnal IOP was also strong in older glaucoma subjects (r=.601, P< .001) and moderate in older healthy subjects (r=.412, P< .05), but absent in younger healthy subjects (r=- .077, P=.672). Conclusion: Using a modification of the diurnal IOP curve, the magnitude of peak nocturnal IOP in untreated glaucoma patients can be estimated during routine office visits. Supine IOP measurements estimate peak nocturnal IOP better than sitting measurements. This estimation may provide the clinician with valuable information regarding the nocturnal IOP peak in glaucoma patients.
