Corneal Biomechanics

Corneal opacities are the fourth cause of blindness (i.e., 5.1%) after cataract, glaucoma, and age-related macular degeneration. Corneal opacities include keratoconus, corneal dystrophies, corneal injuries, etc. Penetrating keratoplasty (PK) has been an effective procedure in treating these corneal disorders. Worldwide, approximately 12.7 million people, and in India 1.2 million are still waiting for the transplantation. To overcome the shortage of donor corneas demands the need for an alternative such as bio-synthetic corneas. Over the last decade, several researchers have been exploring the Biosynthetic Cornea. However, the properties of long-term stability and toughness of the bio-synthetic cornea remain a challenge. The mechanical and surgical stability and ability to maintain its functionality during and after the transplant are desirable in corneal transplants. After the transplant, numerous factors such as suture tension, intra-ocular pressure (IOP), and the anisotropic nature of the material result in distortion of the cornea. This thesis brings out some key mechanical parameters of the human cornea needed for PK that would address the long-term in-vivo stability of the bio-synthetic cornea.

Team

Corneal Optomechanics

The interaction of alteration in corneal microstructure and physiological forces contributes to the optical outcomes of any refractive correction procedure. The current clinical paradigm involves a topographic assessment of the cornea, which does not take into account the biomechanical parameters of the cornea. Multiple techniques such as PSOCT, ocular response analyzer, etc have been devised so far to assess the biomechanical aspect of the cornea to obtain more reliable outcomes of refractive surgeries. This research is dedicated towards exploring the microstructural features of the cornea by its measuring birefringence property using the technique of digital photoelasticity and translate its abilities to help identify structural abnormalities of the cornea. This will aid to bring in patient specificity in a clinical setting and help in planning customized surgeries. We are trying to explore the applicability of digital photoelasticity in various surgical scenarios such as penetrating keratoplasty, collagen cross-linking, corneal ectasia, etc. Additionally, this work is also focused on developing finite element models of the human cornea and characterizing its biomechanical behavior. 

Team

Analysis of Glacouma Drain Devices

Implantation of a glaucoma drainage device (GDD) is a procedure of choice in the management of refractory glaucoma. The two most commonly implanted glaucoma drainage devices are the Ahmed glaucoma valve (AGV) and the Baerveldt implant. The initial study was designed to critically investigate the mechanism of valve action and the consistency in the flow characteristics of the AGV under simulated physiological conditions in vitro. The initial study was also designed to evaluate if the magnitude of the resistance offered during priming has any effect on the performance of the device. An experimental setup was developed in the initial study to analyze the flow characteristics and later it was used for analyzing the faulty GDD.  A blade was designed that can be used for slicing of the AGV leaflets helped to convert the flow-restrictive AGV into a non–flow-restrictive device. Flow characteristics by our in-vitro study confirmed the loss of resistance of AGV valve leaflets. This blade can revive the drainage through the same implant, by converting the flow-restrictive implant into a non– flow-restrictive device, which could avoid the second implant and its economic and surgical implications.

Team