A cataract is an opacity or cloudiness in the natural lens of the eye. It is still the leading cause of blindness worldwide and represents an important cause of visual impairment in the United States. The development of cataracts in the adult is related to aging, sunlight exposure, smoking, poor nutrition, eye trauma, systemic diseases, and certain medications such as steroids.

Cataract

Clear Lens

The progression of cataracts is highly variable, however, they will invariably worsen in severity. Changing glasses may sometimes be useful in improving vision as the cataract progresses. For most patients, however, changing glasses has minimal impact on overall visual quality. Besides changing glasses, the only other option for treatment of cataracts is cataract surgery.

The decision for cataract surgery is reached only between the EyeMD and the patient. In general, this decision is based on the degree to which the patient's vision is impaired, and the impact that impairment has on his or her quality of life. When a patient is significantly bothered by symptoms of cataract, cataract surgery is usually offered.

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Diabetic retinopathy is the leading cause of acquired blindness among Americans under the age of 65. The great majority of this blindness can be prevented with proper examination and treatment. Unfortunately, patients who are not properly referred for evaluation and management or those who, for any reason, fail to get proper eye care are at the greatest risk of vision loss.

Background diabetic retinopathy (BDR) may occur at any point in time after the onset of diabetes. In general, this is the first "stage" of diabetic retinopathy and, therefore, the least concerning. This condition is often present without any visual symptoms. Findings in the retina include dot and blot hemorrhages (tiny hemorrhages in the retina itself), microaneurysms (out-pouchings of capillaries), and exudates (retinal deposits occurring as a result of leaky vessels). The development of this condition in type I (juvenile-onset) diabetics is rarely present prior to three or four years following the onset of diabetes. In type II (adult-onset) diabetics, background diabetic retinopathy may be present at the time of diagnosis of the condition.

Diabetic Retinopathy (Enlarged)

Diabetic Retinopathy Diagram

Clinically significant macular edema (CSME) is a condition of swelling of the macula related to the development of leaky capillaries and microaneurysms. This condition may or may not be associated with reduced or distorted vision. Ophthalmologists use rather strict criteria to determine whether a patient should be treated with focal laser photocoagulation for this condition. These criteria were set forth by the studies mentioned above.

Proliferative diabetic retinopathy (PDR) carries the greatest risk of visual loss of the conditions discussed thus far. The condition is characterized by the development of neovascularization (new, abnormal vessel growth) on or adjacent to the optic nerve and vitreous or pre-retinal hemorrhage (hemorrhage in the vitreous humor or in front of the retina). PDR usually occurs in eyes with advanced background diabetic retinopathy. Unfortunately, the neovascular vessels are abnormal and have a tendency to break and bleed into the vitreous humor of the eye.

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Glaucoma is a disorder associated with pressure in the eye, and is characterized by damage to the optic nerve, with consequent visual loss, initially peripheral, but potentially blinding if relentlessly progressive. Unfortunately, glaucoma is usually a disease in which the patient is entirely asymptomatic (without symptoms) until late in the disease.

Glaucoma affects 2 million Americans, and half of those people are unaware they have the disease. Approximately 5 to 10 million Americans have elevated eye pressure, which places them at risk for the development of glaucoma. Eighty thousand Americans are already blind from the disease. African-Americans have a five-fold greater risk of developing glaucoma and, in this population; it is the single most common cause of irreversible blindness.

Glaucoma

In recent years, it has been shown that at least one-third of glaucoma patients have eye pressures in the "normal range", which is 10 to 21mm Hg. This information has challenged traditional thought that glaucoma is a disorder of high eye pressure. There are consequently multiple theories regarding the cause of glaucoma. Suffice it to say that besides eye pressure, perfusion (blood flow) of the optic nerve, mechanical factors in and around the optic nerve itself, and biochemical factors also probably play a role. Studies have shown that elevated eye pressure may lead to the development of glaucoma if left untreated.

There are many risk factors for glaucoma, and these must be taken into account in the management of patients with suspected or manifest glaucoma. The strongest risk factors include elevated intraocular (eye) pressure, family history of glaucoma, advanced age, and being of African-American descent. Other risk factors include cardiovascular disease (e.g., history of heart attack or stroke), diabetes mellitus (sugar diabetes), myopia (nearsightedness) and high blood pressure.

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Age related macular degeneration (AMD) is the leading cause of legal blindness in the elderly Caucasian population, but is relatively rare in other races. The degenerative condition of the central retina (macula) only affects central vision, leaving peripheral vision intact. AMD affects approximately 30% or more of the Caucasian population age 75 and greater and, while no one knows the exact cause of this disorder, a genetic link has been made. The primary lesion appears to occur deep to the central retina with deposits known as drusen. Drusen are thought to be metabolic by-products, the increasing deposition of which may further interfere with the high metabolic activity of the macula.

Risk factors for vision loss with AMD include advancing age, hyperopia (farsightedness), family history of AMD, exposure to ultraviolet (UV) light, smoking, and high blood pressure. There are two basic forms of AMD: "dry" AMD and "wet" AMD. The latter of these is the more visually debilitating form.

"Dry" AMD

The deposition of drusen typically begins in the middle-aged and progressively worsens over a period of many years, perhaps several decades.

This is associated with increasing macular destruction and gradual reduction in central vision.

"Dry " AMD accounts for 90% of cases and, fortunately, does not usually cause total loss of reading vision. Patients with this form of AMD must be monitored quite closely, as the condition may deteriorate into "wet" AMD.

"Wet" AMD

The "wet" form of AMD accounts for only 10% of all cases, and is more visually debilitating. This form of the disease occurs when a tiny frond of vessels (capillaries) breaks through the lowest layer of the retina, and grows beneath the macula.

This is known as a choroidal neovascular membrane (CNVM). The abnormal vessels of the CNVM may leak fluid causing a localized swelling, or worse, result in a localized bleed.

This is the condition most likely to result in legal blindness. It is important to realize, however, that even "wet" AMD doesn't lead to complete blindness, given that peripheral vision remains intact.

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Treatment of AMD

There is no specific treatment for "dry" AMD, though a multitude of studies is in progress in search of prevention or a cure. Studies have shown that certain vitamins and anti-oxidants help slow down the progression of "dry" AMD. As stated earlier, patients with "dry" AMD should be carefully monitored for development of "wet" AMD. Treatment for the "wet" form of AMD is aimed at minimizing visual loss and/or minimizing the size of the resulting central "blind spot". Different kinds of laser treatments have been used to slow down or eliminate the progression of the CNVMs that can form under or around the macula.
Over the last two or three years there have been large advances in the treatment of "wet" AMD. These treatment methods have mostly gone away from the use of lasers to treat the CNVM and use different medications to slow the progression.

In 2004, Pegaptanib (Macugen), was introduced as a new way of treating "wet" AMD. It was the first approved treatment that targeted the proteins that are responsible for the growth of a CNVM. Different studies published in the New England Journal of Medicine have shown that Macugen was able to prevent the growth of the abnormal blood vessels that cause CNVMs and preserve vision.

Over the last year, there has been a large breakthrough in the treatment of "wet" AMD with the use of Bevacizumab (Avastin) and more recently (approved on June 30, 2006 by the FDA) Ranabizumab (Lucentis). Both of these drugs have not only been shown to slow down, and in some cases stop, the deterioration in vision from "wet" AMD, but, in some cases, bring about significant improvements in vision. Both of these drugs can improve visual acuity with 35% of patients experiencing significant improvement. Clinical trials are still being run with both of these medications, but early results have shown remarkable results with improved visual acuity.

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