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Kimberly Metzler, Ashraf M. Mahmoud, Jun Liu, David Lee, Sue J. Shiao, Cynthia J. Roberts; Biomechanical Response of Paired Donor Corneas to An Air Puff: Isolated Cornea vs Intact Whole Globe. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6793.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the deformation characteristics of human donor corneas mounted in an artificial anterior chamber and as a whole globe, in response to an air puff.
Human donor eyes were obtained in matched pairs for a total of 10 eyes of 5 donors. One eye of each pair was secured in a custom-designed whole globe (WG) mount using shallow sutures in the sclera. Two 25-gauge needles were inserted through the sclera into the anterior chamber of the eye, one to manipulate pressure and one to monitor output. The cornea of the fellow eye was removed with a 16mm trephine and placed in a Barron disposable artificial anterior chamber (AC). WG and AC corneas were mounted sequentially onto a tripod and connected to a GE Dash 4000 Patient Monitor. Deformation data were acquired using the CorVis ST (Oculus, Wetzlar, Germany), a new device which captures a series of approximately 140 Scheimpflug images of a single horizontal meridian during a 30ms air puff. Internal pressure was set to 10, 20, 30, 40 and 50mmHg and a minimum of 4 exams were performed at each pressure level. Deformation data were analyzed using a paired t-test.
WG had 3 OS, 2 OD and AC had 2 OS, 3 OD. Significantly higher maximum deformation amplitude was observed with WG than AC at all pressures (the mean differences in amplitudes are 0.917 ± 0.207mm, 0.577 ± 0.141mm, 0.396 ± 0.097mm, 0.270 ± 0.0574mm, and 0.130 ± 0.093mm at pressures 10, 20, 30, 40, and 50 mmHg, respectively); p-values obtained from a paired t-test for pressures of 10, 20, 30, 40, and 50 mmHg were 0.0006, 0.0008, 0.0008, 0.0005, and 0.0348, respectively. Furthermore, linear regression of the difference in deformation amplitude between WG and AC demonstrated a significant decrease with increasing pressure (p < 0.001, R2 = 0.8434).
Corneal deformation response to an air puff is affected by the type of mount used. This has implications on interpretation of in vivo readings from air puff examinations which may be affected by other ocular structures in addition to the cornea. Future studies will include a larger sample size, and evaluate other deformation parameters, including hysteresis.
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