age-related macular degeneration

age-related macular degeneration
Name	age-related macular degeneration
Caption	A fundus photograph showing advanced age-related macular degeneration.
Field	Ophthalmology
Symptoms	Blurred or reduced central vision
Complications	Legal blindness
Onset	Older age
Duration	Chronic
Types	Dry (atrophic), Wet (neovascular)
Causes	Damage to the macula
Risks	Smoking, Hypertension, Family history, Caucasian race
Diagnosis	Dilated eye examination, Fundus photography, Optical coherence tomography
Prevention	AREDS supplements, not smoking
Treatment	Anti-VEGF injections, Photodynamic therapy, Laser photocoagulation
Medication	Aflibercept, Ranibizumab, Bevacizumab
Prognosis	Variable; central vision loss often progresses
Frequency	Leading cause of vision loss in the developed world

age-related macular degeneration is a medical condition which may result in blurred or no vision in the center of the visual field. It is a leading cause of severe vision impairment and legal blindness among older adults in the developed world. The disease involves the progressive deterioration of the macula, the central part of the retina responsible for sharp, detailed vision.

Signs and symptoms

Early stages are often asymptomatic, but as it progresses, individuals may notice blurred or distorted central vision. A common early sign is difficulty with tasks like reading or recognizing faces. In the dry form, symptoms typically worsen gradually, while the wet form can cause rapid and severe vision loss. Patients may also perceive straight lines as wavy, a symptom known as metamorphopsia, which can be detected using an Amsler grid. Advanced cases can lead to central scotoma, a blind spot that significantly impairs activities like driving.

Causes and risk factors

The exact cause is complex and multifactorial, involving a combination of genetic, environmental, and lifestyle factors. The most significant non-modifiable risk factor is advanced age. A strong family history and genetic predispositions, such as variants in the CFH and ARMS2 genes, increase risk. Modifiable risk factors include smoking, which doubles the risk, and hypertension. Other factors include obesity, a diet low in antioxidants, and prolonged exposure to ultraviolet light. Individuals of Caucasian race are at higher risk compared to those of African descent.

Pathophysiology

The disease is characterized by degenerative changes in the retinal pigment epithelium and the choroid. In the dry form, also known as atrophic, cellular debris called drusen accumulate between the retina and the choroid, leading to geographic atrophy of the retinal pigment epithelium and photoreceptors. The wet form, or neovascular, is marked by the abnormal growth of new blood vessels from the choroid into the subretinal space, a process called choroidal neovascularization. These fragile vessels leak fluid and blood, causing rapid damage to the macula and photoreceptor cells.

Diagnosis

Diagnosis is primarily made through a comprehensive dilated eye examination performed by an ophthalmologist. Fundus photography is used to document the appearance of the retina and the presence of drusen or hemorrhage. Optical coherence tomography provides high-resolution cross-sectional images to assess retinal thickness and detect fluid from neovascularization. Fluorescein angiography involves injecting a dye to visualize leaking blood vessels in the wet form. The Amsler grid is a simple tool for patients to self-monitor for metamorphopsia.

Management

There is no cure, but management aims to slow progression and preserve vision. For the dry form, the AREDS and AREDS2 studies formulated specific dietary supplements containing high doses of vitamin C, vitamin E, zinc, copper, lutein, and zeaxanthin. For wet age-related macular degeneration, the standard treatment is intravitreal injections of anti-VEGF drugs such as aflibercept, ranibizumab, and bevacizumab to inhibit abnormal blood vessel growth. Other therapies include photodynamic therapy with verteporfin and, less commonly, laser photocoagulation. Low vision rehabilitation is critical for advanced cases.

Epidemiology

It is the most common cause of irreversible vision loss in individuals over 50 in the developed world. Prevalence increases dramatically with age, affecting about 2% of people aged 50-59 and nearly 30% of those over 75. Global estimates from the World Health Organization indicate it affects millions. Incidence is highest in populations of European ancestry, with lower rates reported in Asia and Africa. With aging populations in countries like the United States and those in the European Union, the number of affected individuals is projected to rise significantly.

Category:Ophthalmology Category:Geriatrics Category:Blindness