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Keyton Clayson, Yanhui Ma, Xueliang Pan, Elias Pavlatos, Jun Liu; Corneal hydration control and effect on whole eye inflation. Invest. Ophthalmol. Vis. Sci. 2019;60(9):6804.
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© ARVO (1962-2015); The Authors (2016-present)
To develop an effective method to restore and maintain physiological hydration in ex vivo porcine and human corneas during whole globe experimentation and to investigate the effect of hydration on corneal inflation response.
Porcine and human whole globes were obtained and tested within 72 hrs postmortem. Thirty porcine buttons with a scleral ring were treated for 24 hrs in one of 5 concentrations (0% [untreated], 2.5%, 3.0%, 3.5%, or 4.0%, n=6 per group) of poloxamer-188 in 0.9% saline (P188), a surfactant shown to deswell corneas. Corneal hydration H was obtained as (wet weight-dry weight)/dry weight. Whole porcine globes were subjected to inflation testing from 5-30 mmHg either without treatment (n=6, control) or after deswelling at 4oC via immersion in 3.25% P188 until CCT stabilized as measured by ultrasound pachymetry (n=6). Axial (i.e. through-thickness) strains were obtained using high-resolution ultrasound imaging (50MHz, MS700, VisualSonics) and a speckle-tracking technique (Tang & Liu, JBME 2012). These studies were repeated in human corneal buttons (n=4 per group in 3.5% or 4.25% P188) and whole globes (n=4 per group in 3.5% or 4.25% P188) to estimate corneal hydration H and its effect on corneal inflation response.
Near physiological hydration (i.e. H=3.2) was obtained with 3.0%-3.5% P188 treatment in porcine cornea (Fig. 1A) and 4.25% P188 treatment in human cornea (Fig. 2A). P188 treatment of human donor whole globes reduced posterior stromal folding (Fig. 2B). CCT was stabilized after 18-24 hrs of treatment, returning to near physiological levels with 3.25% P188 in porcine (891±66 µm) and 4.25% P188 in human (574±34 µm) eyes (Figs. 1C,2C). Corneal axial strains at 30 mmHg were larger at physiological hydration than in swollen cornea in both porcine (-6.42%±1.50% vs. -3.64%±1.05%, Fig. 1D) and human (-2.85%±0.09% in vs. -1.53%±0.27%, Fig. 2D) eyes.
P188 treatment was effective in restoring and maintaining near physiological corneal hydration during ex vivo testing. Hydration appeared to significantly impact through-thickness corneal inflation response in both porcine and human eyes.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Fig. 1. Hydration H in porcine corneas (A), and representative ultrasound images (B), CCT (C), and axial strains (D) before and after P188 treatment.
Fig. 2. Hydration H in human corneas (A), and representative ultrasound images (B), CCT (C), and axial strains (D) before and after P188 treatment.
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