According to the American Diabetes Association, (ADA, 2014) diabetes mellitus can be defined as a metabolic disorder characterized by high blood sugar which is known as hyperglycemia. It can be categorized into three classes; diabetes type 1, diabetes type 2 and gestational diabetes. Type 2 is the most common one. It is mainly caused by resistance of body cells to insulin, which is involved in regulation of blood sugar. This results in abnormally high levels of sugar, a conditioned known as hyperglycemia. Diabetes eye diseases occur as a complication associated with the high blood sugar. These diseases are: diabetes retinopathy, diabetes macular edema, cataracts and glaucoma. Diabetes retinopathy is the most common one. Diabetes macular edema is associated with diabetes retinopathy. Glaucoma and cataracts can develop secondarily after development of retinopathy. These diseases may cause difficulty in seeing and may ultimately result in blindness. In the discussion below, the anatomy of the eye has been explained to detail and the circumstances that would lead to retinopathy, the stages in retinopathy, and the way this can be handled in order to spare Mr. Smith’s eyesight.
Anatomy of the Eye
The eye is the organ involved in sight.it converts light rays into signals that are transmitted into the brain where they are interpreted. When the word eye is mentioned it sparks up three terminologies that are very relevant to the topic. According to P. Kronfeld, (2014) the anatomy of the eye can be discussed under the following categories; the eyeball, the orbit and extra ocular muscles. The gross anatomy and embryology of the eye. The orbit refers to bony structure of the skull where the eye ball is located. The eyeball is the functional part of an eye that is involved in the transduction of light rays into signals. The eyeball is surrounded by an upper and lower eyelid with eye lashes. These are a protective mechanism against physical damage of the eyeball. The outer transparent layer covering the eyeball is known as the conjunctiva. Part of the eye that appears white and surrounds a colored section is called sclera, while the colored section is known as iris. The iris has different kinds of pigmentations depending on the race which one belongs to. The central part of the iris is an aperture known as the pupil. The iris expands and constricts to alter the size of the pupil in order to focus the light rays. Behind the iris is a transparent convex lens which converge the rays on the retina. At the back of the eyeball is the retina. This is a light sensitive layer of cells involved in the transduction of light to signal. It contains rods and cone cells. The area of sharpest vision is known as fovea reticularis. The signal is transmitted through the optic disk to the optic nerve then to the brain. There is are two chambers filled with fluid; the aqueous and vitreous humor. The extra ocular muscles coordinate the movement of the eyeball upwards, downwards and sideways.
Mechanism of Vision
In view Martin J. Touvee (2013) the major function of the eye is to trap light rays and focus them on the retina (p.10). Introduction to visual systems Light rays are able to reach the retina due to the transparent nature of the eyeball structures. It first passes through the conjunctiva. The iris restricts the amount of light entering the eye. When the light is too bright, it constricts reducing the amount of light reaching the retina. If the light is too dim it relaxes widening the pupil. The iris has melanin pigment to absorb stray rays which would form multiple images. The lens converges the rays to form an image on the retina. The retina has a black pigment that prevents the light rays from bouncing back. The rods and cones transduce light energy into signal transmitted through optic nerve to the part of the brain that interprets the signal into an image that can be perceived.
This is a condition that results from high amounts of blood sugar, a characteristic of diabetes mellitus. A persistently high blood sugar leads to destruction of the blood vessels of the retina. It leads to leakage of the blood vessel contents which distorts vision. The main reasons for loss of vision in patients with diabetes mellitus are diabetic macular edema and proliferative diabetic retinopathy (M. Netwich and W. Ulbig, 2015, p.1) Diabetes retinopathy progresses in four distinct stages. The first stage is mild non proliferative retinopathy.in this stage there is only swelling of small blood vessels a condition referred to as micro aneurysms. Vision is minimally distorted. The second is moderate non proliferative retinopathy.in this case blood vessels swell and may lose their ability nourish the retina. This stage is associated with diabetes macula edema and it cause changes in retinal appearance.in the third stage, severe non proliferative retinopathy, a growth factor that promotes growth of new blood vessels is released. In the final advanced stage, proliferative diabetic retinopathy, new blood vessels grow from the retina. They are more fragile and likely to leak and bleed. As the vessels heal scar formation may cause contraction that can detach the retina. This may lead to permanent vision loss.
Diabetes retinopathy develops due to failure of proper management of the blood sugar levels. According to Kilari, E. K., & Putta, S. (2017). Taking the medication correctly and taking a healthy diet delays vision loss. Delayed Progression of Diabetic Cataract genesis and Retinopathy, Cutaneous and ocular toxicology,36 (1), 52-59. Medication includes insulin and other hyperglycemic drugs. Dilated eye exam is also necessary to monitor progression. Retinopathy in Mr. Smith can be managed through therapies and adhering to doctors’ advice on medication and diet
The American Diabetes Association. (2014). Diagnosis and Classification of Diabetes Mellitus. Diabetes care,37(Supplement 1), S81-S90.
Kronfeld. P. C. (2014). The Gross Anatomy and Embryology of the Eye. The Eye, 1(968), 1.
Martin J .Tovee (2001). Introduction to visual systems; eye and forming images.(10-17)
Nentwich, M. M., & Ulbig, M. W.(2015). Diabetic retinopathy-ocular complications of diabetes mellitus. World journal of diabetes, 6(3), 489.
American Diabetes Association. (2014). Executive summary: standards of medical care in diabetes—2014.
Kilari, E. K., & Putta, S. (2017). Delayed progression of diabetic cataractogenesis and retinopathy by Litchi chinensis in STZ-induced diabetic rats. Cutaneous and ocular toxicology, 36(1), 52-59.