Abstract
Purpose :
The lamina cribrosa (LC) posterior displacement in glaucoma is known to be dependent on the interplay of IOP and CSF pressure as well as tissue material properties. By performing Valsalva maneuver, the LC can displace as the dynamics of IOP and CSF pressure change. This study tested whether the degree of LC displacement during Valsalva maneuver varied according to the age in healthy subjects.
Methods :
Thirty-four eyes of 34 healthy volunteers (age range: 20–76 years) underwent IOP measurement and Cirrus HD-OCT optic disc scans before and during standardized Valsalva maneuver. The subjects were asked to exhale into a mouthpiece and instructed to maintain the expiratory pressure at a minimal level of 30 mmHg for over 15 seconds. The subjects had a five-minute break after each standardized Valsalva maneuver. The optic nerve head (ONH) parameters (average retinal nerve fiber layer thickness, rim area, disc area, average cup-to-disc ratio, cup volume), anterior LC depth (LCD), Bruch’s membrane opening (BMO) distance, and peripapillary vessel density were measured and compared during Valsalva challenge. Factors associated with the degree of LC displacement were analyzed.
Results :
During the standardized Valsalva maneuver, the IOP significantly increased from 13.3±2.6 mmHg to 19.5±4.9 mmHg (P<0.001), while the LCD decreased from 451.9±103.2 μm to 429.9±104.4 μm (P<0.001). The LCD change revealed significant positive correlation with age (younger eyes tended to displace more anteriorly during Valsalva challenge). The ONH parameters, BMO distance, and peripapillary vessel density did not change significantly (all P>0.05). Younger age (P=0.017) and smaller increase of IOP during Valsalva maneuver (P=0.006) were associated with the more anterior displacement of LC during Valsalva maneuver.
Conclusions :
The LC displacement during Valsalva maneuver varied with the age and IOP change. This is consistent with the previous experimental animal studies and biomechanical models based on finite element analysis. By performing Valsalva maneuver, we may judge the stiffness of LC in noninvasive manner.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.