Analysis of the intraocular jet flows and pressure gradients induced by air and fluid infusion: mechanism of focal chorioretinal damage.
OBJECTIVE
To comprehend the mechanism of focal chorioretinal damage by analysis of the pressure distribution and dynamic pressure induced by infused air during fluid-air exchange.


METHODS
A precise simulation featuring a model eye and a fluid circuit was designed to analyze fluid-air exchange. The pressure distribution, flow velocity, and dynamic pressure induced by infusion of air into an air-filled eye were analyzed using an approach based on fluid dynamics. The size of the port and the infusion pressure were varied during simulated iterations. We simulated infusion of an air-filled eye with balanced salt solution (BSS) to better understand the mechanism of chorioretinal damage induced by infused air.


RESULTS
Infused air was projected straight toward a point on the retina contralateral to the infusion port (the "vulnerable point"). The highest pressure was evident at the vulnerable point, and the lowest pressure was recorded on most retinal areas. Simulations using greater infusion pressure and a port of larger size were associated with elevations in dynamic pressure and the pressure gradient. The pressure gradients were 2.8 and 5.1 mm Hg, respectively, when infusion pressures of 30 and 50 mm Hg were delivered through a 20-gauge port. The pressure gradient associated with BSS infusion was greater than that created by air, but lasted for only a moment.


CONCLUSIONS
Our simulation explains the mechanism of focal chorioretinal damage in numerical terms. Infused air induces a prolonged increase in focal pressure on the vulnerable point, and this may be responsible for visual field defects arising after fluid-air exchange.
Department of Ophthalmology, Soonchunhyang University College of Medicine, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea.
Yong Joon
YJ
Kim
Department of Mechanical Engineering, Soonchunhyang University, Asan, Republic of Korea.
Sungkil
S
Jo
Nune Eye Hospital, Seoul, Republic of Korea.
Daruchi
D
Moon
Department of Mechanical Engineering, Soonchunhyang University, Asan, Republic of Korea.
Youngcheol
Y
Joo
Department of Ophthalmology, Soonchunhyang University College of Medicine, Soonchunhyang University Seoul Hospital, Seoul, Republic of Korea.
Kyung Seek
KS
Choi
D000388:Air; D002829:Choroid / Q000293:injuries* / Q000473:pathology; D003198:Computer Simulation; D005131:Eye Injuries / Q000150:complications / Q000175:diagnosis*; D006801:Humans; D021621:Imaging, Three-Dimensional; D011312:Pressure / Q000009:adverse effects; D012160:Retina / Q000293:injuries* / Q000473:pathology; D012607:Scotoma / Q000175:diagnosis* / Q000209:etiology
chorioretinal damage; fluid-air exchange; pressure gradient; visual field defect