Ph.D. Dissertation Defense Announcement
Candidate: William Ebo Annan
Date: Friday, May 30, 2025
Time: 1:00 PM (EST)
Location: Snell Hall, Room 212
Zoom Link: https://clarkson.zoom.us/j/93326272372?pwd=dMAt0b37R2Pi4V2abt2lbPyVJFmAb4.1
Dissertation Title: Modeling the Progression of Retinal Detachment and Its Effects on the Dynamics of Rod Outer Segment Renewal
Advisors: Dr. Emmanuel O. Asante-Asamani and Dr. Diana White
Modeling the progression of retinal detachment and its effects on the dynamics of rod outer segment renewal
The retina is a tissue layer lining the interior of vertebrate eyes. It is composed of two layers: the neural layer (NL) and the retinal pigmented epithelium (RPE). Retinal detachment (RD) is a medical condition in which the NL separates from the RPE, typically due to aging, trauma, injury, or inflammatory diseases such as diabetes. During detachment, photoreceptor cells in the NL are deprived of essential nutrients and metabolic support, which leads to cell death and, ultimately, irreversible vision loss. The rate at which RD progresses and the key factors influencing its progression remain poorly understood. This lack of understanding often contributes to treatment delays, which may result in permanent vision loss even after successful retinal reattachment. Photoreceptor cells, consisting of rods and cones have an outer segment (OS), a section that contains stacks of thin membranous structures called discs embedded with proteins essential for converting light energy into electrical signals. Throughout life, the OS undergo daily renewal process where new discs are added to the base while the older ones are removed from the tip to prevent accumulation of toxins that can affect the health of the cell. Although RD has been shown to disrupt this renewal mechanism, the precise effects remain unclear. Some studies suggest that disc addition at the base ceases during detachment, while others indicate that disc synthesis continues. Furthermore, the normal shedding process, which relies on the RPE to engulf and degrade OS discs, is believed to halt due to the physical separation of the NL from the RPE. Nevertheless, it has been observed that photoreceptor OS continue to degenerate or shorten following detachment.
In this study, we first develop a system of ordinary differential equations (ODEs) to model the renewal dynamics of the photoreceptor OS during RD, with the aim of predicting how detachment impacts the renewal process and leads to OS degeneration. The model also enables us to estimate the survival time of a rod cell in a detached retina.
Subsequently, we construct a Retinal Progression Fluid–Structure Interaction (RP-FSI) model to study the progression of RD. This model allows us to investigate how various factors, including fluid viscosity and density, retinal thickness, density, and elasticity, as well as the average rate of eye rotation and molecular properties of the adhesion proteins binding the NL to the RPE–influence the dynamics and extent of detachment.
Student: William Ebo Annan
Advisors: Prof. Emmanuel O. Asante-Asante & Prof. Diana White