Ocular surface disorders such as Lid Wiper Epitheliopathy (LWE), Superior Epithelial Arcuate Lesion (SEAL), and contact lens-induced Limbal Stem Cell Deficiency (LSCD) as well as Superior Limbic Keratoconjunctivitis (SLK) affect one’s quality of life. Hence, it is imperative to investigate the underlying causes of these ocular surface disorders. During blink, the undersurface of the eyelid tends to interact with the cornea and the conjunctiva. The presence of a contact lens can add to the biomechanical frictional changes on these surfaces. To estimate these changes with and without a contact lens, a finite element model (FEM) of the eyelid wiper, eyeball, and contact lens was developed using COMSOL Multiphysics. Biomechanical properties such as von Mises stress (VMS) and displacement were calculated. Our study concluded that (a) maximum VMS was observed in the lid wiper in the absence of contact lens in the eye and (b) maximum VMS was observed in the superior 1.3 mm of the cornea in the presence of the contact lens in the eye. Thus, the development of friction-induced ocular surface disorders such as LWE, SLK, SEAL, and LSCD could be attributed to increased VMS. FEA is a useful simulation tool that helps us to understand the effect of blink on a normal eye with and without CL.

A three dimensional finite element model of the human eye is developed to evaluate the force which will be applied over the surface of cornea during tonometry and gonioscopy tests. The standard tonometers and gonioscopy experiences deformation from 0.5mm to 3mm of the cornea is adopted during both point contact and boundary contact on the surface of the cornea. The results demonstrate the maximum force experienced by the tonometer with point contact at the center of the cornea for the maximum possible deformation of the cornea during tonometry. The study also analyzes for the force experienced by the tonometer or goniolens with boundary layer contact for the defined deformation of the cornea along the direction from cornea towards the retina.

Purpose: Excess force on cornea during eye care testing procedure such as tonometry may damage the internal structure of eye or may result in erroneous results. The proposed work can be utilized or incorporated as an additional feedback mechanism in the technology innovation of design of eye care instruments. Method: This work is focused on biomechanical simulation of human eye to determine applanation force on cornea and also to find the influence of intraocular pressure (IOP) of eye on Tonometry. Results: The results summarise that force applied by the tonometer will increase linearly for increase in deformation of cornea and the junction of cornea and sclera will undergo maximum deformation and hence will experience maximum stress compared to the centre of cornea where tonometer applanates the cornea. Conclusion: The tonometry will result in deformation of cornea in vertical elongation and the maximum stress is concentrated at the tonometer periphery as well as at the junction of cornea and sclera. The investigation also report that rise in IOP of eye demands higher force of applanation to get the prescribed deformation of cornea.

Contact Lens-related Discomfort (CLD) is one of the major problems in about 50% of contact lens users. It is a symptom of a variety of conditions such as Lid Wiper Epitheliopathy (LWE), Superior Epithelial Arcuate Lesion (SEAL), Limbal Stem Cell Deficiency (LSCD), Superior Limbic Keratoconjunctivitis (SLK) and dry eye disease; which affect the quality of life. Hence, it is essential to investigate the underlying cause of CLD. During a blink, the under surface of the eyelid tends to interact with the cornea and the conjunctiva. The presence of a contact lens can add to the biomechanical changes on these surfaces. To estimate these changes with and without a contact lens, a Finite Element Model (FEM) of the eyelid wiper, eyeball and contact lens was developed using COMSOL Multiphysics®. Biomechanical properties such as von Mises stress and displacement were calculated. Our study concluded that large stress formed in the lid wiper could be the reason for the occurrence of LWE and SLK without contact lens in the eye. When the contact lens was in situ, large stress was found in the superior 1.3mm of the cornea which could be responsible for the development of SEAL and superior LSCD.

Purpose Discover the associations of force of applanation on the eye with the plunging depth of the cornea and quantify them. The results will be utilized as the feedback parameter in the new prototype development of eye care instruments as additional force may damage the internal structure of the eye or may result in erroneous output. Method A finite element-based eye model is designed utilizing the actual dimensions of the human eye. A standardized tonometer is designed and the simulation is carried out at predetermined deformation of the cornea to find the force of applanation on the cornea during tonometry. Adding on, the influence of IOP during tonometry is analyzed for a range of plunging depths of the cornea. Results The graphical results inferred the linear relation between the force of applanation with the deformation of the cornea and the results are quantified. The resulting deformation and stress plot of FEM based simulation approach is analyzed and observations regarding deformations and stress are made. Conclusion The human eye is successfully developed and also computed force on the cornea during tonometry is validated. The inference drawn from the deformation plot and stress plot is that the junction of cornea–sclera along with cornea-tonometer periphery undergo maximum deformation and experiences the highest stress compared to other areas of the eye while during tonometry.