Poster Session: Experimental assessment of scleral anisotropy using multi-meridian air-coupled ultrasonic optical coherence elastography.

Scleral biomechanics plays a key role in the understanding of myopia progression. In this study, we characterized the elastic properties of sclera using an air-coupled ultrasonic (ACUS) optical coherence elastography (OCE) system. New Zealand rabbit eyes (n=7) were measured (<24hr postmortem) in four scleral locations: superior/inferior temporal (ST, IT), and superior/inferior nasal (SN, IN) maintaining an intraocular pressure of 15 mmHg. Elastic waves were induced in the sclera, and wave propagation velocity and shear modulus were measured along two directions: circumferential (superior-inferior) and meridional (nasal-temporal). Wave velocity in scleral tissue ranged from 6 to 24 m/s and shear modulus from 11 to 150 kPa. Velocity was significantly higher (p<.001) in the circumferential vs. meridional directions in the following locations: ST:15.83±2.85 vs 9.43±1.68 m/s, IT:15.00±3.98 vs 8.93±1.53 m/s; SN:16.79±4.30 vs 9.27±1.47 m/s; and IN:13.92±3.85 vs 8.57±1.46 m/s. The average shear modulus in the circumferential was also significantly higher (p<.001) than in the meridional direction for all locations: 65.37±6.04 vs 22.55±1.36 kPa. These results show that the rabbit sclera is mechanically anisotropic with higher rigidity in the circumferential direction compared to the meridional direction. ACUS-OCE is a promising non-invasive method to quantify the biomechanical changes in scleral tissue for future studies involving myopia treatments.

Evaluation of the optic nerve and scleral-choroidal-retinal layer with ultrasound elastography in glaucoma and physiological optic nerve head cupping.

AIM: To evaluate the strain ratio of the optic nerve and retina-choroid-sclera (RCS) layers in individuals with physiological optic disc cupping (PC) and glaucoma patients using strain elastography. MATERIAL AND METHODS: We evaluated 56 eyes of 56 subjects (20 eyes with glaucoma, 19 eyes with PC, and 17 normal eyes). The strain ratio of orbital fat to optic nerve (SROFON) was calculated as the ratio of the optic nerve to intraconal fat tissue and the strain ratio of orbital fat to retina-choroid-sclera (SROFRCS) was calculated as the ratio of RCS layers to intraconal fat tissue. RESULTS: SROFON was 0.92 in the control group, 1.07 in the PC group and 1.6 in the glaucoma group and a statistically significant difference was present between the three groups (p<0.05). SROFRCS had no statistically significant difference between the three groups. CONCLUSIONS:  SROFON values could contribute to the differentiation of the patients with glaucoma and PC.

[Combined deep sclerectomy and trabeculotomy in congenital glaucoma with complications]. / Kombinierte tiefe Sklerektomie und Trabekulotomie beim komplizierten kongenitalen Glaukom.

BACKGROUND: Lately there has been growing interest in deep sclerectomy as a therapeutic approach for the management of congenital glaucoma.In theory, its pressure-lowering effect is independent of external filtration, which minimizes the risk of failure due to conjunctival or episcleral scarring. In patients who have failed to benefit from previous filtering procedures and have refractory congenital glaucoma,deep sclerectomy could become an alternative. PATIENTS AND METHODS: A 3-year-old girl with refractory congenital glaucoma underwent deep sclerectomy in her left eye. Intraoperatively, percolation through the trabeculodescemetic window was weak, so that the procedure was supplemented by a trabeculotomy. RESULTS: By now, throughout a follow-up period of 20 months, stabilisation of disc cupping and ocular axial length has been achieved without additional glaucoma surgery or medications. CONCLUSIONS: In patients with congenital glaucoma,the combination of deep sclerectomy with trabeculotomy may provide an additional therapeutic approach whenever the prospect of success appears to be limited with deep sclerectomy alone.