Opthalmic Tissue Engineering by Kyle Pariseau

OVERVIEW

The ophthalmic organ, also known as the eye, is an important sensory organ that allows us to perceive the world we live in. In 2014 the World Health Organization (WHO) estimated that 285 million people worldwide are visually impaired [2]. The most common eye conditions are refractive errors (nearsightedness/farsightedness), cataracts, glaucoma, dry eye, macular degeneration, and diabetic retinopathy. Among these eye conditions, cataract is the leading contributor to vision impairment. The current treatment for most of the conditions is generally surgery to correct the issue. Research has been done over the years to engineer various parts of the eye to correct damages caused by diseases or physical injury.

Refractive Errors:

Refractive errors are the most frequent problems in the U.S. There are a few different types of errors; there is myopia (nearsightedness), hyperopia (farsightedness), astigmatism, and presbyopia. In general, these errors are the result of the cornea changing shape or aging of the lens. This causes light to not properly focus on the retina causing images to be blurred and distorted. Corrections can be done with eyeglasses, contacts, and laser surgery [5].

Cataracts:

Cataracts prevalence increases with age and affects nearly 17.2% of Americans age 40 and older [3]. Cataract is a clouding of the lens causing vision to blur. This cloudiness is the result of some of the proteins on the lens clumping together. As more proteins clump, the cloudier the lens becomes. The current treatment for cataracts is surgery to remove the lens and replace it with an artificial lens. [1]

Glaucoma:

Glaucoma is the result of increased fluid pressure in the eye. This increased pressure can damage the retina and optic nerve ultimately leading to vision loss. Glaucoma can be split into two categories: open angle and closed angle glaucoma. Open angle glaucoma affects vision over a long period of time whereas with closed angle glaucoma, vision loss occurs suddenly [3]. The current treatment for glaucoma is through surgery or drugs. Laser surgery is becoming more popular in open angle glaucoma due to its success rates.

Diabetic Retinopathy: Diabetic retinopathy affects more than 4.1 million Americans between the ages of 20-74 [3]. This disease is a common complication of diabetes and is the result of damage to blood vessels in the retina or the growth of abnormal blood vessels in the retina. Current treatment is with laser surgery where lasers are used to burn the vessels to cause them to shrink [4].

Current Research

Laser (Lasik) Surgery video on Youtube: https://www.youtube.com/watch?v=qoH0VHrOM9A

Cornea Regeneration:

The cornea has two main functions. The first function is to act as a protective barrier for the rest of the eye. The cornea also acts as an outer lens that focuses light to the pupil. Damage to the cornea can result in loss of vision. Studies have been conducted to help regenerate the cornea as well as create an artificial cornea.

In a recent study, scientists have found that hydrogel scaffolds are a suitable means of regenerating damaged corneas. These hydrogel scaffolds are made up of networks of recombinant human collagen type III and 2-methacryloyloxyethyl phosphorylcholine (RHCIII–MPC) [10]. The cornea is made up of collagen type I naturally. Collagen type III behaves closely to that of type I collagen, allowing for the RHCIII-MPC scaffold to promote cell regeneration on the cornea. To maximize the efficiency of cellular regeneration on the hydrogel, scientists had to figure out the appropriate concentrations of water and collagen. With the suitable concentrations of water and collagen, scientists were able to create a suitable gel that they could implant. They tested this gel on mini-pigs and found that this gel allowed for regeneration of the cornea [10]. The table below give the concentrations of each component in the hydrogel.

[10]