Regional variations in the biomechanical properties of the isolated porcine retina: potential implications for subretinal injection.

PURPOSE: To determine how the biomechanical properties of the retina vary across different quadrants of the eye and how commonly used storage media affect retinal biomechanics. METHODS: A total of 130 retinal strips were dissected from 90 six-month-old pigs eyes for uniaxial tensile testing. Vertical and horizontal strips were extracted from each quadrant, with ten samples per group. Four different storage media-Ringer's solution, balanced salt solution (BSS), phosphate-buffered saline (PBS), and vitreous-were used. Strip thickness was measured using calibrated optical microscopy. Tensile testing was conducted at an extension rate of 9 mm/min. RESULTS: Ringer's solution significantly affected the mechanical properties of the retina, making the samples stiffer (25.5 ± 5.6 kPa) and stronger (12.8 ± 1.5 kPa) than the control (2.6 ± 1.3 kPa; 1.8 ± 0.7 kPa). A significant difference (p < 0.05) in tensile strength and tangent modulus was found between the blood vessel group (2.6 ± 0.5 KPa, 5.2 ± 1.6 KPa) and the temporal-horizontal group without blood vessels (1.4 ± 0.4 KPa, 3 ± 1.1 KPa). The inferior-horizontal group showed a significantly higher tensile strength than the inferior-vertical group (p = 0.019). CONCLUSION: Blood vessels significantly impact retinal biomechanics. The retina also showed anisotropic behaviour with tensile properties varying by strip orientation within the same location. The storage media used can significantly affect biomechanical properties. TRANSLATIONAL RELEVANCE: Biomechanical properties of the retina significantly impact the outcome of subretinal injections and other surgical procedures. Understanding how these properties vary across the retina could optimise strategies for subretinal bleb generation.