Peripapillary atrophy (PPA) is a condition where tissues surrounding the optic nerve at the back of the eye thin and degenerate. This area, normally a healthy pink or red, can change in appearance when these layers are affected. The change is like soil eroding from the base of a plant; the structure is there, but its supporting ground has worn away. PPA is not a disease, but a clinical finding an eye doctor might observe during an examination, and is often found in healthy eyes.
The Two Types of Peripapillary Atrophy
Clinicians recognize two distinct zones of peripapillary atrophy, the Alpha zone and the Beta zone, distinguished by their appearance and location. The Alpha zone is the outermost area and is characterized by changes in pigmentation within the retinal pigment epithelium (RPE), a layer of cells that nourishes the retina. This zone may appear as an area of irregular light and dark spots.
The Beta zone is located closer to the optic nerve, between the nerve itself and the Alpha zone. This area represents a more significant degree of tissue thinning, where both the RPE and the underlying choroid have atrophied. This thinning makes the white, underlying sclera and larger choroidal blood vessels more visible. The Beta zone is considered more clinically significant, as its presence and size are more strongly correlated with damage associated with certain eye conditions.
Underlying Causes and Associated Conditions
Peripapillary atrophy can develop due to a few different factors, ranging from normal physiological changes to signs of an underlying ocular condition. One of the most common associations is with the natural aging process, where tissues in the eye can gradually thin over time. Another frequent cause is high myopia (severe nearsightedness), where the eyeball is elongated, causing retinal layers at the back of the eye to stretch and thin. It is estimated that PPA is present in about 20% of individuals with high myopia.
The most significant association of PPA is with glaucoma, a disease that damages the optic nerve and can lead to vision loss. The presence of PPA, particularly the Beta zone, is an indicator of glaucomatous damage or a heightened risk for the disease’s progression. The tissue thinning in PPA corresponds with the nerve fiber layer loss and visual field defects characteristic of glaucoma.
Diagnosis and Monitoring
An eye doctor identifies peripapillary atrophy during a dilated fundus examination, which involves using a special lens and a bright light for a clear view of the back of the eye. This direct visualization, also known as ophthalmoscopy, allows the doctor to see the optic nerve and surrounding retinal tissue, noting any changes that suggest PPA. To create a baseline record and track changes, fundus photography is used to take detailed pictures of the optic nerve area.
For a more precise analysis, Optical Coherence Tomography (OCT) is invaluable. An OCT scan is a non-invasive imaging test that uses light waves to take cross-section pictures of the retina. This allows for the exact measurement of the thickness of the retinal layers in the peripapillary region.
Monitoring PPA involves comparing fundus photographs and OCT scans from different appointments to detect progression in the atrophic zones. This tracking is important when PPA is associated with glaucoma, as an increase in atrophy can signal that the underlying disease is worsening.
Impact on Vision and Management
The presence of peripapillary atrophy itself does not directly cause vision loss; any changes to sight result from the underlying condition. For instance, if glaucoma is the cause, vision loss is due to optic nerve damage from eye pressure, not from the PPA. In cases of high myopia, vision problems are related to the eye’s shape and other myopic changes.
There is no treatment for peripapillary atrophy because it is a physical change in the tissue, much like a scar. The focus of any medical intervention is directed at managing the associated primary condition. If an examination reveals PPA linked to glaucoma, an ophthalmologist will initiate treatment to lower intraocular pressure, using medicated eye drops or laser procedures to prevent further optic nerve damage.
The discovery of PPA serves as an important clue for the eye doctor, guiding them to manage potentially serious eye diseases. Management, therefore, is not about reversing the atrophy but about controlling the condition that led to it. For patients, this means that addressing the root cause is the way to protect overall vision and eye health.