Peripapillary Atrophy: Causes, Types, and Eye Health

Peripapillary atrophy (PPA) is a thinning or loss of tissue in the ring-shaped zone surrounding the optic nerve head at the back of the eye. It shows up on a retinal exam as a crescent or halo of lighter or darker discoloration around the optic disc, and it is remarkably common, appearing in healthy eyes as well as in eyes affected by nearsightedness or glaucoma. What makes PPA clinically interesting is not just that it exists but what its size, shape, and structure can reveal about the health of the optic nerve and the trajectory of certain eye diseases.

What PPA Actually Looks Like Under the Microscope

When an eye doctor spots PPA during a fundus exam, the visible change is a pale or mottled ring at the edge of the optic disc. What is happening at the tissue level is more involved. The retinal pigment epithelium (RPE), a single layer of cells that supports and nourishes the light-sensing photoreceptors, becomes irregular or disappears altogether in the affected zone. In the area closest to the disc edge, Bruch’s membrane (the thin tissue layer beneath the RPE) can be completely stripped of its pigment cells, and the photoreceptors above it are severely reduced or gone entirely.¹ Farther out from the disc, the RPE cells are still present but disorganized, with uneven pigment distribution and partial cell loss.

Beneath these surface-level changes, deeper structures are also affected. The inner portion of Bruch’s membrane thickens, and the tiny blood vessels of the choriocapillaris (the capillary bed that feeds the outer retina) shrink or vanish. One histological study found that rod photoreceptors degenerate and disappear at the point where Bruch’s membrane terminates near the disc, while cone photoreceptors are relatively spared. Complete loss of the choriocapillaris tracked closely with full RPE atrophy, suggesting a vicious cycle: as the blood supply dwindles, the pigment cells die, and as the pigment cells die, the photoreceptors lose their metabolic support.²

The Zone System for Classifying PPA

For decades, clinicians divided PPA into two concentric bands. Zone alpha sits at the outer edge, where the RPE is irregular but still present. Zone beta lies closer to the disc and represents the more severe form, where the RPE and choriocapillaris are largely absent and the underlying sclera or choroid becomes visible as a pale crescent. This classic two-zone scheme has been the workhorse of clinical research linking PPA to glaucoma.

More recently, researchers introduced two additional labels, zone gamma and zone delta, to capture features seen especially in highly nearsighted eyes.³ Zone gamma refers to a region where Bruch’s membrane itself is absent, exposing the elongated scleral flange that forms when the eyeball stretches in myopia. Zone delta sits between gamma and the disc border and is associated with the optic nerve itself being displaced or tilted. In a study of 600 highly myopic eyes, larger gamma zones correlated strongly with wider delta zones, longer distances between the disc and the fovea, and more chorioretinal atrophic lesions, all markers of the mechanical stretching that high myopia inflicts on the back of the eye.⁴

The practical point of splitting PPA into finer categories is that not all peripapillary tissue loss means the same thing. A wide gamma zone in a very nearsighted person tells a different story than an irregular beta zone in someone with normal eye length and rising eye pressure. The zone system helps clinicians separate the mechanical footprint of myopia from the damage pattern of glaucoma, a distinction that matters for treatment decisions.

Causes and Driving Mechanisms

PPA does not have a single cause. Several processes can produce it, sometimes working together in the same eye.

Aging: Some degree of peripapillary tissue thinning develops with normal aging, much as skin thins over time. The RPE loses pigment, Bruch’s membrane stiffens, and the choriocapillaris gradually thins. This age-related form is typically mild and stable.
Myopia: As a nearsighted eye grows longer, the sclera stretches, pulling the surrounding tissue with it. The zone of bare Bruch’s membrane (or absent Bruch’s membrane entirely, in extreme cases) expands. Research in young school children found that the width of beta-zone PPA could serve as a predictor of further myopia progression, suggesting that PPA enlargement is both a consequence and a marker of ongoing scleral stretching.⁵
Glaucoma: In glaucomatous eyes, damage to the optic nerve head and surrounding tissue leads to progressive enlargement of beta-zone PPA. The tissue loss is thought to reflect both mechanical strain from elevated or fluctuating intraocular pressure and ischemic damage from inadequate blood flow.
Vascular insufficiency: Poor blood supply to the peripapillary region can contribute to tissue atrophy even outside of glaucoma. Microvascular dropout, detectable with advanced imaging, has been linked to worse outcomes in conditions like optic neuritis, where eyes with peripapillary microvascular dropout showed significantly thinner ganglion cell layers at six months compared to eyes without it.⁶

The Glaucoma Connection

The relationship between PPA and glaucoma is the most clinically studied aspect of peripapillary atrophy, and it is genuinely useful even though it is not a simple “PPA means glaucoma” equation. Beta-zone PPA is found more often and is larger in glaucomatous eyes than in healthy ones, and it tends to enlarge over time as glaucoma progresses. A longitudinal study following patients for an average of about twelve years found that beta-zone PPA expanded in roughly two-thirds of eyes with primary open-angle glaucoma, compared with about a quarter of normal eyes. The odds of PPA widening were about two and a half times higher in glaucoma eyes even after accounting for age.⁷

The location and shape of PPA carry prognostic weight. In patients with normal-tension glaucoma, the position of the atrophic zone around the disc correlates with where visual field defects appear.⁸ A separate study in treated open-angle glaucoma found that the hemifield containing the largest area of beta-zone PPA predicted where visual field loss would progress fastest in about seven out of ten patients.⁹ In other words, PPA is not just a passive marker. Its geography around the disc can tell a clinician which part of the visual field is most vulnerable.

Even the border shape matters. Research comparing glaucoma patients who progressed in visual field testing with those who remained stable over about ten years found that the total area of beta-zone PPA was similar between the two groups at baseline. What differed was the irregularity of the PPA border: patients whose PPA margins were more ragged and uneven were significantly more likely to progress. An irregular PPA border, along with optic disc hemorrhage, was an independent predictor of future visual field loss.¹⁰ This finding is clinically handy because it means that clinicians should look not just at how much PPA a patient has but at the character of its margins.

On a structural level, wider PPA that includes loss of Bruch’s membrane has been associated with faster visual field decline in open-angle glaucoma, including in highly myopic eyes where separating glaucoma damage from myopic stretching is already difficult.¹¹ Larger PPA area also tracks with worse visual field scores and thinner ganglion cell layers over time, making it a useful structural surrogate when following glaucoma progression alongside the standard visual field and nerve fiber measurements.¹²

Microvascular Dropout and Blood Pressure Patterns

One of the more active research areas around PPA involves the tiny blood vessels of the choroid that supply the peripapillary region. Using optical coherence tomography angiography (OCTA), a noninvasive imaging method that maps blood flow without dye injection, researchers can now visualize focal areas where the choroidal microvasculature simply drops out. These microvascular dropouts appear disproportionately in glaucomatous eyes and are linked to central visual field damage. In one study of open-angle glaucoma patients with central field loss, microvascular dropout was present in about 78% of affected eyes, compared with only about 2% of eyes with intact central fields. Systemic factors including cold extremities, migraine, lower mean arterial pressure, and lower ocular perfusion pressure were all associated with the presence of dropout.¹³

The blood pressure connection goes deeper than what happens during the day. In patients with normal-tension glaucoma, researchers have examined how nighttime blood pressure dipping relates to choroidal vessel density in the beta-zone PPA area. Patients whose blood pressure dropped excessively at night (“over-dippers”) had lower peripapillary choroidal vessel density than those with normal or absent dipping. Choroidal vessel density was a consistent predictor of excessive nocturnal blood pressure dipping across multiple statistical models.¹⁴ This suggests that in at least some glaucoma patients, the health of the peripapillary circulation is tangled up with systemic cardiovascular regulation, an insight that is slowly broadening how clinicians think about glaucoma risk beyond eye pressure alone.

Separating Myopic PPA From Glaucomatous PPA

High myopia and glaucoma both produce beta-zone PPA, and a large percentage of highly nearsighted people develop glaucoma at some point, which means the two causes frequently overlap in the same eye. Telling them apart matters because the prognosis and management are different.

Histological work comparing eyes with chronic angle-closure glaucoma to eyes with high myopia alone found distinct tissue signatures. Glaucomatous beta zones were accompanied by a recognizable alpha zone, drusen-like deposits along the RPE near the disc, thickened Bruch’s membrane, and higher RPE cell counts at the border. Myopic beta zones lacked these features: no distinct alpha zone, no parapapillary drusen, unremarkable Bruch’s membrane thickness, and unremarkable RPE density at the margins.¹⁵ These differences suggest that the two types of beta zone arise from fundamentally different processes: mechanical stretching in myopia versus inflammatory and pressure-related damage in glaucoma.

In clinical practice, this distinction plays out through imaging. An eye with a huge gamma zone and a tilted disc but a regular beta-zone border is more likely showing the effects of extreme axial elongation. An eye with a smaller but irregular beta zone, disc hemorrhages, and progressive nerve fiber thinning is raising glaucoma alarms. The expanded zone classification system described earlier helps clinicians mentally separate these patterns, though the judgment call can still be difficult in borderline cases.

When PPA Fools the Imaging Equipment

PPA can create practical headaches in the clinic, especially when it interferes with the automated measurements that eye doctors rely on to track glaucoma. Optical coherence tomography (OCT) measures the thickness of the retinal nerve fiber layer (RNFL) by scanning a circle around the optic disc. That scan circle is designed to sit outside the typical PPA zone, but when PPA is large, the scan path can cross into atrophic tissue. The result is an artificially thin RNFL reading that mimics glaucoma damage even if the nerve fibers are intact farther out.

A study of imaging artifacts on the Spectralis OCT platform found that PPA was consistently associated with poor scan quality and inaccurate RNFL measurements. Most affected scans showed artifactually thinner readings, meaning the machine reported worse nerve fiber health than actually existed.¹⁶ For patients with large PPA, clinicians need to check that the scan circle did not cross into the atrophic zone and, if it did, interpret the numbers with appropriate skepticism. This is one of those situations where the automated printout can mislead if it is taken at face value without looking at the raw scan images.

OCTA has added a complementary dimension by mapping peripapillary vessel density. In primary angle-closure glaucoma, the inferior quadrant vessel density had the highest diagnostic accuracy for distinguishing glaucomatous from healthy eyes, and in some clock-hour sectors, vessel density outperformed RNFL thickness as a diagnostic marker.¹⁷ Combining structural thickness measurements with blood flow maps gives clinicians more information to work with, particularly when PPA is muddying the structural data.

AI-Assisted PPA Detection

PPA segmentation, the process of outlining the atrophic area on a retinal image, has traditionally been done by hand or with semi-automated tools. It is time-consuming and subject to variability between graders. This has made PPA a natural target for deep learning algorithms, which can process fundus photographs at scale.

One approach transformed the irregularly shaped PPA region into two more regularly shaped sub-regions and used a multi-task convolutional neural network to extract them jointly, achieving an average precision of about 0.89 against expert-labeled images.¹⁸ Another deep learning model trained to classify PPA for glaucoma screening achieved area-under-the-curve scores ranging from 0.83 to 0.89 across local and public datasets.¹⁹ These numbers are promising for a screening tool, though they reflect performance against curated image sets rather than messy real-world clinical photos with variable lighting and camera angles.

The potential payoff is large. If algorithms can reliably measure PPA area and border irregularity from standard fundus photos, the prognostic information currently locked in specialist interpretation could become available at the primary care level or in teleophthalmology programs serving areas without glaucoma specialists. Review articles cataloging the various segmentation and classification methods published so far note a steady march from traditional feature-extraction techniques toward end-to-end deep learning, with performance improving at each step.²⁰ The gap between research performance and clinic-ready deployment is still real, but the direction of travel is clear.

What PPA Means if You Have Been Told You Have It

If your eye doctor mentions peripapillary atrophy, the first thing to understand is that having some PPA does not automatically mean you have glaucoma or that you are going blind. Mild alpha-zone changes are common in the general population and increase with age. The finding becomes more clinically meaningful if the PPA is large, if it is in the beta zone (visible as a clearly pale crescent where the pigment cells and blood vessels are gone), if its borders are irregular, or if it is enlarging over time.

For people with myopia, PPA is part of the structural package that comes with a longer eyeball. Your doctor will likely monitor it alongside your prescription changes and retinal health, particularly if you are in the moderate-to-high myopia range. For glaucoma patients or suspects, PPA is one more data point in the constellation of findings, alongside eye pressure, nerve fiber thickness, visual field tests, and disc appearance, that guides how aggressively treatment needs to be pursued. The location and shape of your PPA may even help your doctor anticipate which part of your peripheral vision is most at risk, which can influence how closely particular sectors of your visual field are watched.

People whose blood pressure drops steeply at night or who have vascular symptoms like cold hands or migraines should be aware that these systemic factors have been linked to worse peripapillary blood flow in glaucoma. If you fall into that group, your ophthalmologist and primary care doctor may want to coordinate, especially if you are on blood pressure medications that could be amplifying nighttime dips. None of this is cause for alarm on its own, but it underscores that the health of the tissue around the optic disc is not purely an eye issue.