bubble_chart Overview

Senile macular degeneration, also known as age-related macular degeneration or aging macular degeneration, typically begins around the age of 50, with prevalence increasing with age. There is no significant correlation between the disease and gender or race. Both eyes may be affected simultaneously or sequentially. Based on clinical manifestations, it is classified into atrophic and exudative types, with the former being more common and the latter accounting for only 1/10 to 1/15 of the former.

bubble_chart Etiology

The cause of the disease has not yet been determined and may be related to genetics, chronic light damage, nutritional disorders, poisoning, immune diseases, systemic diseases such as the {|###|}heart blood{###|} vascular system and respiratory system, among others. It could also be the result of a combination of multiple factors.

This disease is an aging change in the structure of the macula. The main manifestation is the reduced ability of retinal {|###|}membrane{###|} pigment epithelial cells to phagocytose and digest the outer segment discs of photoreceptor cells. As a result, incompletely digested disc {|###|}membrane{###|} remnants (residual bodies) accumulate in the cytoplasm of basal cells and are excreted extracellularly, depositing in Bruch's {|###|}membrane{###|}, forming drusen. Due to the structural and functional specificity of the macula, this change is more pronounced. Drusen are classified into four types: hard, soft, confluent, and calcified. Drusen are also found in elderly individuals with normal vision, but when followed by various pathological changes, they lead to macular degeneration.

bubble_chart Clinical Manifestations

The disease is divided into atrophic and exudative types as mentioned earlier. Some have observed that the atrophic type can transform into the exudative type, hence the necessity for classification. However, for the majority of cases, the clinical manifestations and prognosis differ markedly between the two types.

1. Atrophic Senile Macular Degeneration (Atrophic Senile Macular Degeneration) The atrophic type is also known as the dry or non-exudative type. Both eyes often develop the disease simultaneously and progress in sync. Its clinical course and manifestations are identical to those of senile hereditary macular degeneration (i.e., Haab's disease). Whether they are the same condition is difficult to determine due to both occurring in the elderly and the challenges in conducting family lineage investigations. The hallmark of this type is progressive pigment epithelial atrophy, clinically divided into two stages:

⑴ Early Stage (Preatrophic Stage): Central vision is grade I impaired, and it may remain normal or near-normal for a considerable period. A central disc-shaped scotoma of 5–10º can be detected in the visual field, more easily with blue or yellow targets. Static perimetry along the 180º line shows reduced sensitivity 5–10º on either side of 0º. The Amsler grid test is often positive. Occasionally, macropsia or micropsia may occur.

On ophthalmoscopy, the macula exhibits relatively dense hard drusen of varying sizes, some merging into small patches. Between the drusen, there are scattered areas of depigmentation and pigment clumping, giving a salt-and-pepper appearance. This lesion centers on the fovea and gradually extends outward without clear boundaries. In some cases, the entire macula appears dark and murky. Slit-lamp microscopy with a precorneal lens reveals slight elevation with a surrounding red halo (lantern phenomenon), suggesting shallow detachment of the pigment epithelium. In this stage, fluorescent spots intensify quickly, peaking within the first minute of the venous phase, then fading to match the background fluorescence and gradually disappearing. In a few cases, fluorescent masking persists after the background fluorescence fades. Cases with shallow pigment epithelial detachment show round or oval fluorescent spots in the initial stage [first stage], which intensify in the intermediate stage [second stage] and gradually fade in the advanced stage. The absence of fluorescent spot enlargement indicates no neovascularization beneath the pigment epithelium or the presence of only fine, undetectable vessels (occult neovascularization).

⑵ Advanced Stage (Atrophic Stage): Central vision is severely impaired, with an absolute central scotoma. Ophthalmoscopy reveals dense or confluent drusen and large, pale gray atrophic areas with well-defined borders, scattered with salt-and-pepper spots and metallic reflections (beaten bronze appearance).

Fluorescein angiography shows intense fluorescence in the atrophic area early on, fading synchronously with the background fluorescence. The absence of fluorescent spot enlargement throughout the process suggests window defects due to pigment epithelial atrophy. However, some cases exhibit both hyperfluorescent and hypofluorescent spots within the atrophic area, indicating atrophy and occlusion of the choriocapillaris in addition to pigment epithelial atrophy.

Atrophic degeneration progresses slowly, with a protracted course. The transition between early and advanced stages is gradual and indistinct. Due to significant individual variability, the time from early to advanced stage varies, but the degree of fundus lesions is generally symmetrical in both eyes.

2. Exudative senile macular degeneration (exudative senile macular degeneration) Exudative, also known as wet, is what Kuhnt-Junius referred to as senile disciform macular degeneration (senile disciform macular degeneration). The hallmark of this type is the presence of active neovascularization beneath the retinal pigment epithelium, leading to a series of exudative, hemorrhagic, and scarring changes. Clinically, it is classified into the late stage [third stage].

⑴ Early stage (predisciform stage): Central vision is significantly impaired, with the degree varying depending on whether the fovea is involved. Amsler grid test is positive. A central relative scotoma can be detected corresponding to the lesion.

On funduscopy, the macular area shows dense, variably sized drusen, predominantly soft and confluent. Pigmentary changes and depigmented spots may also be observed irregularly, with some pigment spots surrounding the drusen in a halo pattern. The foveal reflex is dim or absent. Fluorescein angiography at this stage reveals early fluorescence in areas of drusen and pigment loss, with enhancement, weakening, and disappearance synchronized with background fluorescence. In some cases, strong fluorescent spots persist after the background fluorescence fades, indicating two possibilities: drusen staining or the presence of subretinal neovascularization. The distinction lies in the fact that the former shows expanding fluorescent spots throughout the process, while the latter does not.

⑵ Intermediate stage [second stage] (evolutionary stage): The hallmark of this stage is the formation of serous or hemorrhagic detachment of the retinal pigment epithelium and/or neurosensory retina due to neovascular leakage. Vision declines sharply. Funduscopy reveals, in addition to the early changes described above, larger, dull-colored, round or oval lesions with slight elevation, giving the affected area a mottled gray appearance. Some cases may also exhibit dark red hemorrhagic spots. Slit-lamp biomicroscopy with a contact lens shows serous exudation beneath the pigment epithelium and/or neurosensory retina, with hemorrhages in similar locations. As the condition progresses, yellowish-white exudates appear in the deeper retinal layers. These exudates may present as uniform patches, clusters of varying density, or irregular rings or crescents (Coats reaction) around the lesion margins. Severe hemorrhage can lead to dark red or gray-brown hematomas beneath the pigment epithelium or neurosensory retina. In some cases, flame-shaped hemorrhages may extend into the nerve fiber layer, or blood may breach the internal limiting membrane into the vitreous, causing vitreous hemorrhage. Early fluorescein angiography shows mottled fluorescence in the lesion area, quickly followed by lace-like or cartwheel patterns, indicating active neovascularization. Subsequently, fluorescence spreads and intensifies, filling the detachment cavity by the venous phase or slightly later. Well-defined fluorescence suggests pigment epithelial detachment, while poorly defined fluorescence indicates neurosensory detachment. The strong fluorescence within the detachment cavity persists after background fluorescence fades. The fluorescence is usually uniform, but areas of pigment hyperplasia or hemorrhage may block fluorescence. In cases of severe neovascular rupture leading to hematomas, large areas of fluorescence blockage are observed. In late angiography phases, one or two gradually intensifying and expanding fluorescent spots (hot spots) may appear within these blocked areas, confirming the presence of subretinal neovascularization.

(3) Advanced stage (reparative stage): Exudation and hemorrhage gradually subside and are replaced by scar tissue. At this stage, vision is further impaired. Fundus examination reveals slightly elevated, clustered or irregular white patches (appearing reddish-yellow during hematoma absorption). These patches are located beneath the retinal blood vessels. On the surface or edges of the patches, hemorrhagic spots and pigment spots are often visible. In some cases, after the hemorrhage and exudation are replaced by scars, the lesion does not end there. Instead, new neovascularization appears at the edges of the scars, undergoing the cycle of exudation, hemorrhage, absorption, and scarring again. This repetition leads to further expansion of the scar tissue. Therefore, long-term follow-up observation is essential for such patients. Fluorescein angiography findings at this stage show light-colored scars exhibiting pseudofluorescence; areas of pigment hyperplasia show fluorescence blockage. If there is neovascularization along with exudation and hemorrhage at the edges or within the scars, gradually expanding and intensifying fluorescent spots are observed. Exudative age-related macular degeneration typically affects both eyes sequentially, with an interval generally not exceeding five years.

bubble_chart Treatment Measures

Since the cause of this disease is still unclear, there is currently no effective treatment or fundamental preventive measures. In recent years, most scholars advocate that for exudative cases, laser photocoagulation of neovascularization should be performed as early as possible to prevent the condition from worsening. Argon laser can effectively seal subretinal neovascularization, so it is currently widely used. However, it causes some damage to the neuroepithelial layer, so it should be avoided for neovascularization within 200μ near the fovea or between the optic disc and macula. In addition to argon laser, there are also krypton laser, Nd:YAG laser, and dye laser, which can be selected based on the location of neovascularization, the amount of nearby pigment, and whether there is bleeding obscuring the area. Laser photocoagulation is only intended to seal existing neovascularization and cannot prevent the formation of new neovascularization; it is a symptomatic treatment. At the same time, even slight excess laser energy can itself induce choroidal neovascularization, so caution is necessary.

Anti-aging and circulation-improving Chinese medicinals have shown good efficacy for the atrophic type of this disease. They also play a certain role in preventing recurrence after scar repair in exudative cases and in halting the progression of the disease in the other eye.

In recent years, the relationship between the trace element zinc and retinal diseases has gained attention. Zinc is highly concentrated in ocular tissues, particularly in the retinal pigment epithelium and choroid, and is involved in the activity of many enzymes such as vitamin A₁ dehydrogenase and catalase. Newsonc et al. suggest that oral zinc supplements may prevent the progression of macular degeneration. Additionally, vitamin C and E, as hydroxyl scavengers, can be tried to protect photoreceptor cells from free radical damage.

bubble_chart Differentiation

When the aforementioned various clinical manifestations become evident, diagnosis is not difficult. However, in the early stages of the disease, particularly the atrophic type, it should be differentiated from senile drusen occurring in individuals with normal vision. The main differences, apart from visual function, are that in the former, the drusen vary in size, are quite densely distributed, and have relatively indistinct borders, with pigmentary disturbances such as pigment spots and depigmented patches interspersed among the drusen. In the latter, the drusen are sparse, similar in size, and show no pigmentary disturbances.

In the exudative type, when a hematoma occurs beneath the pigment epithelial layer, it should be differentiated from choroidal melanoma. The most reliable method is fluorescein angiography, where the hematoma appears as a large non-fluorescent area due to blocked background fluorescence. In melanoma, neovascularization within the lesion leads to leakage and the appearance of multiple lake-like hyperfluorescent spots.

For the exudative type in the sudden-onset phase, with exudation and hemorrhage in the macula, especially in younger patients, it should also be differentiated from central exudative choroiditis. The latter does not present with drusen in the fellow eye, and inflammatory cellular opacities can be observed in the posterior vitreous of the affected eye. The former, however, shows antagonism. Additionally, systemic etiological examinations may also provide reference.