Ultrasound Measures of Vitreous Chamber Depth during Ocular Accommodation

Analysis of human crystalline lens accommodation

“…As predicted by the analysis (Fig. 6, d=a % 0:02), during in vivo accommodation the displacement of the posterior lens surface accounts for approximately 30% of the increase in central thickness (Beauchamp and Mitchell, 1985;Drexler et al, 1997).…”

“…The lens is located between the aqueous humor and vitreous; however, the vitreous does not affect accommodative amplitude (Fisher, 1983;Beauchamp and Mitchell, 1985) and therefore is not included in this analysis.…”

Predicting the performance of accommodating intraocular lenses using ray tracing

“…This may be achieved using a variety of mechanical arrangements, some of which may be more efficacious than others. In practice, the actions of the ciliary body and zonules, accompanied by hydraulic and mechanical influences from the vitreous and iris, 27,28 would cause both the front and back elements of the 2E-IOL to shift axially relative to the other components of the eye, as the natural lens does during accommodation, [29][30][31] and the amount of axial shift of each element would differ. The relative amounts of axial shift between the front and back element would be expected to differ from patient to patient 29,31 and also on how closely the back element of the IOL abuts with the anterior vitreous, which in turn would be dependent on the design of the IOL as well as the implantation method and positioning.…”

The relationship between refractive and biometric changes during Edinger–Westphal stimulated accommodation in rhesus monkeys

“…When accommodation occurs, lens equatorial diameter decreases (Storey and Rabie, 1987;Wilson, 1997;Glasser and Kaufman, 1999;Strenk et al, 1999), the lens anterior and posterior surface curvatures steepen (Brown, 1973;Koretz et al, 1984Koretz et al, , 1987Garner and Yap, 1997), anterior chamber depth decreases, lens axial thickness increases (Storey and Rabie, 1983;Koretz et al, 1987;Beers and Van der Heijde, 1996) and the posterior lens surface generally moves posteriorly (Brown, 1973;Beauchamp and Mitchell, 1985;Drexler et al, 1997). The accommodative change in shape of the young lens is brought about by the force the capsule exerts on the lens (Fincham, 1925(Fincham, , 1937Campbell, 1998, 1999;Glasser et al, 2001).…”

“…Axial biometric accommodative changes that can be measured with A-scan ultrasonography are lens thickness (LT) and associated changes in anterior chamber depth (ACD) and vitreous chamber depth (VCD) (Storey and Rabie, 1983;Beauchamp and Mitchell, 1985;Koretz et al, 1997). Anterior segment length (ASL=ACD+LT) can also be determined as an indication of the extent of movement of the posterior lens surface.…”