Abstract
Purpose :
To assess the impact of the IOP on the biometric parameters of the eye. To investigate in vivo the dynamic behavior of ocular components and media of human eyes during air-puff stimulation for different IOP levels.
Methods :
Long-range air-puff SS-OCT instrument operated at 1 μm and the speed of 30,000 A-scans/s enabled in vivo full-eye-length imaging. High spatial and temporal resolution of the system allowed to measure the reaction of all ocular components to the air pulse stimulus (Fig. 1a).
The IOP of 20 healthy eyes (mean age: 28±4 years) was determined using Goldmann applanation tonometer (GAT) and rebound tonometer (RT, Icare)). The OCT data sets consisted of 4000 A-scans acquired along the entire visual axis during 130 ms. The measurements were performed before, 1 hour and 2 hours after administration of IOP-reducing drops (Alphagan).
From OCT data ocular components were segmented to measure temporal deformation profiles of the cornea, the crystalline lens and the retina as well as all intraocular distances (central corneal thickness – CCT, anterior chamber depth – ACD, lens thickness – LT, vitreous depth – VD, axial length - AL) (Fig. 1b).
Results :
The IOP decreased significantly after two hours after Alphagan eye drops’ administration (before: 15.8±4.0 mmHg, 2hrs after: 13.0±2.9 mmHg). Statistically significant correlations were found between intraocular distances (apart from AD and LT) and the IOP measured by RT and GAT (Fig. 2a).
Average deformations for the cornea, the lens and the retina before the IOP reduction were: 1102±88 μm, 249±35 μm and 183±53 μm, respectively. Deformations of the cornea and the lens became higher for lower IOP levels (2 hrs after eye drops: 1240±113 μm, and 265±38 μm). Statistical significance of correlation between corneal / lenticular deformations and the IOP from RT and GAT were found (Fig. 2b).
The comparison of intraocular biometric parameters before and during air-puff showed that the changes in AD and AL correlated significantly with the IOP (Fig. 2c).
Conclusions :
Full-eye-length air-puff SS-OCT enabled complete in vivo characterization of the IOP-related changes of eye’s biometric parameters as well as the impact of the IOP on eye reaction to non-contact air-pulse mechanical stimulation.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.