Retinal Pigment Epithelial Detachment - Causes, Symptoms, Diagnosis, and Management

What Is Retinal Pigment Epithelium?

Retinal pigment epithelium is a uni-layer formation of polygonal cells located in the outer layer of the retina. The retinal pigment epithelium’s outside is connected with Bruch’s membrane, and the inner side is connected with the photoreceptor cell’s inner part. The basal folding of the outer layer increases the surface area, which expedites the swapping of substances. The basal fold is tightly connected to the basement membrane. This tight junction is the reason for the choroid-blood-retinal barrier with Bruch’s membrane and choroid at the lateral side of the retina. Moreover, the retina-pigment epithelium also plays an important role in the reduction of excessive accumulation of reactive oxygen and oxidative damage. This makes retinal pigment epithelium a very important structure in maintaining vision.

Choroidal neovascularization (CNV) and central serous chorioretinopathy are usually associated with retinal pigment epithelial detachment. This condition is typically the result of age-related macular degeneration. However, there are some documented cases related to other conditions causing retinal pigment epithelial detachment.

What Are the Functions of Retinal Pigment Epithelium?

There are the following functions of retinal pigment epithelium:

• To Maintain Visual Cycle and Phagocytosis: Retinal pigment epithelium is an essential structure in maintaining the visual cycle and its functions. This is only possible with the regular renewal of visual cells. Phagocytosis consists of three main steps: binding, endocytosis, and elimination. The binding step is combining the inner microvilli cell membrane with the outer layer of the visual cell. Endocytosis is the procedure where the substances are pushed into the cell. Finally, the elimination process defines the transportation of cytoskeleton and vesicles into lysosomes.

• Protection and Anti-oxidative Functions: Before birth, the pigment particles such as melanin and lipofuscin are produced in utero. These pigment particles play an essential role in the protection of neural parts of the retina from light. As the retina is exposed to many different light stimuli, there is the possibility of photooxidation and oxidative damage. However, the antioxidants that retinal pigment epithelium carries provide protection.

• Barrier and Substance Transport Functions: Retinal pigment epithelium plays a barrier between substance transportation and protects the retina. The substances such as electrolytes, nutrients, and water are transported, and the mechanisms used are endocytosis, passive diffusion, and membrane pump.

How Is the Retinal Pigment Epithelial Detachment Classified?

Retinal pigment detachment is classified into the following types:

• Drusenoid Pigment Epithelial Detachment (PED): The drusenoid PED carries the major risk of dry age-related macular degeneration. Due to stressed retinal pigment epithelium, the debris and fluid are unable to be flushed out, and causes enlargement of subretinal pigment epithelium space.

• Serous Pigment Epithelial Detachment: This type of pigment epithelium detachment is caused by an accumulation of fluid between the Bruch membrane and retinal pigment epithelium. This leads to leakage of the choriocapillaris and reduces the function of the retinal pigment epithelium pump.

• Vascularized Pigment Epithelial Detachment: Vascularized PED is commonly seen as associated with occult choroidal neovascularization (CNV) or subfoveal pathologies. Among many complications associated with this type, progressive visual loss due to hemorrhage or RPE tear is a very common natural course.

What Are the Causes of Retinal Pigment Epithelial Detachment?

The following are the etiological factors associated with retinal pigment epithelial detachment:

• Age: Retinal pigment epithelial detachment is usually seen as associated with age-related macular degeneration.

• Choroidal Neovascularization (CNV): It is the condition that causes abnormal growth of vessels from choroidal vascularization. It is the most commonly associated with age-related macular degeneration.

• Retinal Angiomatous Proliferation: The condition is caused by age-related macular degeneration.

• Polypoidal Choroidal Vasculopathy: It is the condition that causes abnormally shaped vessels that are located in the choroid.

• Association With Treatments: The treatments such as photodynamic therapy, laser photocoagulation, and transpupillary thermotherapy can also be one of the factors causing this condition.

What Are the Signs and Symptoms of Retinal Pigment Epithelial Detachment?

The following are the signs and symptoms associated with retinal pigment epithelial detachment:

• Reduced vision.

• Metamorphosis (a condition where the vision is distorted and the person visualizes straight grid lines).

• Light sensitivity.

How to Diagnose Retinal Pigment Epithelial Detachment?

There are the following diagnostic methods used for retinal pigment epithelial detachment:

• Color Fundus Photography: It is the diagnostic method used to evaluate the retinal pigment epithelium. During this examination, the ophthalmologist looked for the presence of subretinal blood, a sharp and well-defined hyperpigmented line, and the depigmented area of the choroid.

• Fundus Autofluorescence: It is a very good evaluation method used to look for very minor retinal pigment epithelium tears. The hypo-autofluorescence areas with a high level of contrast with the retina give well-defined lesion boundaries.

• Fluorescence Angiography: With this diagnostic method the exposed choroid and rolled retinal pigment epithelium are diagnosed.

• Spectral-Domain Optical Coherence Tomography: There are three parts of this image that shows classic retinal pigment epithelium tear. The first part shows the normal architecture. The second part shows the dome-shaped retinal detachment. The third part shows a neurosensory retina along with no retinal pigment epithelium.

What Are the Complications Associated With Retinal Pigment Epithelial Detachment?

The following are the complications associated with retinal pigment epithelial detachment:

• Choroidal Neovascularization (CNV): It is the condition that is a part of age-related macular degeneration, where there is abnormal vessel growth seen.

• Geographic Atrophy: It is part of age-related macular degeneration, where there is atrophy of outer retinal tissue.

• Visual Impairment: When due to visual acuity, a person’s eyesight is affected and cannot be corrected, it is called visual impairment.

How to Manage Retinal Pigment Epithelial Detachment?

Currently, there is no treatment available for retinal pigment epithelial detachment. However, there are a few management options available for vascularized retinal pigment epithelial detachment:

• Cell Therapy: The stem cell that is derived from an embryo, induced pluripotent, and nuclear transfer is used for the treatment of this condition. Few cases support the local delivery of the cells, whereas the other cases are documented with systemic delivery. Some successful cases suggest that the systemic delivery of the cells provides targeted neovascularization and helps in the treatment.

• Gene Therapy: Gene therapy can be done by the replacement of a particular gene. This is the best-suited therapy for recessive conditions. Angiogenesis causes vision loss and blindness in many people, and vascular endothelial growth factor has proved to be the major factor affecting it. Regular intravitreal injections of humanized anti-vascular endothelial growth factor have proved to be the most effective treatment option.

Conclusion

Retinal pigment epithelium detachment is a condition that usually occurs along with other eye-related complications. No matter its association with CNV, the vision is affected. Although there are no treatment options yet available, it is essential to visit an ophthalmologist at the very first sign of it. With the guidance of a doctor, the symptoms can be managed.