Monday, January 23, 2017,  12:00 – 1:30 pm, in 489 Minor Hall

Graduate Student Seminar

presented by

Stella Kang, PhD Candidate (Chen Lab)

Corneal lymphangiogenesis and valvulogenesis after transplantation

Corneal transplantation is the last hope for vision restoration for patients who are blind from corneal diseases. Using our recently developed live imaging system, we have shown that corneal transplantation induces progressive lymphangiogenesis (LG), which is complicated with valvulogenesis (VG) as LG proceeds. We have also shown that the lymphatic valves express integrin alpha 9 (Itga-9), and they serve to direct the lymph flow insides the vessels. Using an allogeneic transplantation model, we further demonstrate that anti-Itga-9 treatment can effectively reduce the number of valves formed inside the lymphatic vessels and thereby promotes graft survival. Our results not only reveal a critical role of lymphatic VG in transplant rejection, but also offer a novel strategy to treat lymphatic- and immune-related diseases in the body.

 and

Sowmya Ravikumar, PhD

Effect of marginally induced astigmatism on refractive error development in chicks

Purpose: We investigated the effect of marginally induced astigmatism on refractive error development and eye growth in chicks.

Methods: Four groups of chicks were fitted with custom-made two-zone spectacle lenses on one eye, the other serving as control, one week after hatching. Lenses for two treatment groups were Plano in the center and +15D cylinder at axis 90 in the periphery. The other two groups wore lenses that were Plano in the center and +15D sphere in the periphery. One sphere and one cylinder group were fitted with lenses that had 5.5mm central zone diameter (CZD) and the other sphere and cylinder group, with 4.5mm CZD. Each group had 10 chicks. The White-Leghorn chicks were raised with normal diurnal lighting (12 hours off/on). All animal care and treatments conformed to the ARVO statement for the Use of Animals in Ophthalmic and Vision Research. Retinoscopy and A-scan ultrasound
were performed before, 3, 6 & 9 days after, lens insertion. Refraction, Axial Length and other biometric parameters were compared across the groups.

Results: At 9 days of treatment, mean Inter-Ocular Difference (IOD = Treatment eye – Control eye) in spherical equivalent refractive error was -7.53+/-1.81D, for the +15DS periphery 5.5mm CZD; -3.78+/-0.91D, for the +15DCX90 periphery 5.5mm CZD; -11.5+/-1.95D for the +15DS periphery 4.5mm CZD and -4.15+/-2.68D for the +15DCX90 periphery 4.5mm CZD. Optical axial length of treated eyes was shorter than control eyes in both spherical periphery groups (mean IOD of -0.371mm). The Vitreous Chamber Depths of treated eyes were shorter than the control eyes (mean IOD of -0.24mm), the IO differences increasing with duration of lens wear. No statistically significant change was observed either in axial length or vitreous chamber depth for either of the cylindrical groups. Statistically significant choroidal thickening was observed in all four groups, although the change was larger in the spherical compared to cylindrical group.

Conclusions: Whereas with induced positive spherical defocus, the resultant hyperopic change continued to happen monotonically over the course of treatment, with induced positive cylindrical defocus there is an initial shift to hyperopia, followed by a plateau. Nonetheless, when marginal light rays were astigmatically defocused, they had a measurable impact on central refraction. Contrary to some previous studies, we found the end-point of emmetropization to be biased toward the plane of best paraxial focus, not the most myopic plane of best focus for any meridian.

 

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