NU 606 Week 9 Discussion 1: Question-Based Discussion—Team A (Sensory Disorders) Infection and trauma can happen to both the cornea and the conjunctiva. Which is more serious? Using pathophysiology, explain why.

Conjunctiva eye injuries are more serious than those to the cornea. Cornea scratches can usually heal on their own. While mechanisms of injury to the conjunctiva include thermal or chemical burns and blunt or penetrating trauma. Some of the time injuries will be isolated to the conjunctiva, conjunctiva injury can be the presenting sign of underlying intraocular trauma, including open globe injury.

1. Compare wide-angle and narrow-angle glaucoma, including the pathophysiology and signs of each.

Glaucoma involves damage to the structures that allow the aqueous humor to drain out. The two outlets for the draining are trabecular meshwork and uveoscleral outflow. Both of these structures are near the front of the eye, behind the cornea.

Wide-angle glaucoma is the most common form of glaucoma, accounting for 90% of all glaucoma cases. This is caused by the slow clogging of drainage canals than then results in increased pressure in the eye. This was the wide-angle or open-angle between the iris and cornea. The clog is found in the trabecular meshwork. This type of glaucoma can develop slowly and will be a lifelong condition. Many times this the symptoms and damage that occur are not recognized. Sometimes no symptoms are seen before vision is damaged. This is why having regular eye exams is important.

Narrow-angle glaucoma is a less common form of glaucoma. It is a closed or narrow-angle between the iris and cornea. This is found in both the uvesoscleral and trabecular meshwork. This develops very quickly and the symptoms that appear are very noticeable. This demands immediate medical attention.

1. Describe the two types of macular degeneration and current treatments.

The two types of macular degeneration are wet and dry. Dry macular degeneration is the most common, about 90% of cases. In this type, the photosensitive cells of the macular slowly break down. Yellow protein deposits called drusen, extracellular waste products from metabolism, form and accumulate under the retina between the retinal pigmented epithelium (RPE) layer and the Bruch’s membrane. Drusen are often seen in the elderly, but an increase in size and number is an indication of macular degeneration. The drusen leads to the deterioration of the macula and the death of the RPE and photoreceptor cells. This then causes blurring or spotty loss of vision but does not cause pain.

Wet macular degeneration is only seen in about 10% of patients and is considered advanced. This is when abnormal blood vessels grow behind the macula as retinal pigment epithelial cells and photoreceptor cells die. The Bruch’s membrane begins to break down and new blood vessels grow. This is called neovascularization, and are very fragile and clean leak both fluid and blood. This causes scarring of the macula and the potential for rapid, severe damage. Straight vision can become distorted or lost entirely in a short period, sometimes even days.