Evaluation of Iridociliary and Lenticular Elasticity Using Shear-Wave Elastography in Rabbit Eyes

Abstract

Summary:Introduction: A previous study has employed shear-wave ultrasound elastographic imaging to assess corneal rigidity in an ex-vivo porcine eye model. This study employs the same modality in vivo in a rabbit eye model in order to assess lens, ciliary body and total ocular rigidity changes following the instillation of atropine and pilocarpine. Methods: Ten non-pigmented female rabbits were examined. Measurements of the lens, ciliary body and total ocular rigidity as well as lens thickness and anterior chamber depth were taken with the Aixplorer system (SuperSonic Imagine, Aix-en-Provence, France) with the SuperLinear™ SL 15-4 transducer in both eyes at baseline as well as after pilocarpine and atropine instillation. The IOP was also measured with the TonoPen tonometer. Results: Changes in rigidity in the examined areas following atropine instillation were statistically not significant. Ciliary body rigidity was significantly increased whereas lens and total ocular rigidity were significantly reduced following pilocarpine instillation. The decrease in lens rigidity following pilocarpine was significantly associated with the respective increase in ciliary body rigidity. Conclusions: Shear-wave ultrasound elastography can detect in vivo rigidity changes in the anterior segment of the rabbit eye model and may potentially be applied in human eyes, providing useful clinical information on conditions in which rigidity changes play an important role, such as glaucoma, pseudoexfoliation syndrome or presbyopia.

Optical coherence elastography of cold cataract in porcine lens

“… 30 Ultrasound-based shear wave elastography techniques have been used to evaluate the biomechanical properties of various animal lenses. 25 , 31 , 32 However, the low resolution, poor contrast, and large excitation forces of ultrasound-based techniques may not be suitable for in vivo applications. Thus, we propose the use of OCE to detect elastic waves in the lens to characterize lenticular biomechanical properties.…”

The contribution of laboratory animals to diagnostic imaging research in Greece

“…Studies where new user friendly computed models of digital subtraction angiography in the University of Patras have been accomplished and their outcomes are ready to be further used in other experimental and clinical trials (Kagadis et al, 2008). Furthermore, new diagnostic imaging techniques of the eye (Shear-wave ultrasound elastography) are expected to contribute to the precise and early diagnosis of its anatomical abnormalities (Detorakis et al, 2014), whereas original techniques have been used at the last stage of invasive technique studies such as stenting (Kitrou et al, 2014), (Kasapas et al, 2014).…”

The safety and feasibility of diagnostic acoustic radiation force impulse elastography used for eyes. A preliminary in vivo study

“…In recent years the eye elastic properties have been studied using ultrasound elastography (strain or shear wave type), such as corneal elasticity in an ex-vivo porcine eye model [19], iridociliary and lenticular elasticity in an ex-vivo rabbit eye model [20], or vitreous cavity elastic properties in human's blind eyes [21]. The authors pointed out that this modality may potentially be applied in human eyes.…”

“…In ophthalmology the mechanical properties of cornea [19], lens [20], and eye [21,22] have also been studied using elastography. The ocular tissues are particularly susceptible to mechanical and thermal injury associated with excessive ultrasound energy, so that the Food and Drug Administration (FDA) and World Federation for Ultrasound in Medicine and Biology have imposed strict thermal index (TI) and mechanical index (MI) limits for diagnostic ocular ultrasound applications (TI <1.0, MI <0.23) [23].…”