A staphyloma is an abnormal bulging or outpouching of the wall of the eye, where the tissue has become so thin and weakened that it can no longer hold its normal shape. The bulge has a sharper curvature than the surrounding eye wall, creating a localized deformity. Staphylomas can form at the front or back of the eye and range from barely noticeable to severe enough to threaten vision permanently.
How a Staphyloma Forms
The eye is a pressurized sphere. Its outer wall, the sclera (the white part), provides structural support, while the uvea, a layer of tissue rich in blood vessels, sits just beneath it. When the sclera thins or weakens in a specific area, the internal pressure of the eye pushes that weakened spot outward, creating a bulge. In anterior staphylomas (those at the front of the eye), the darker uveal tissue can actually protrude through the defect, giving the area a blue-black discoloration visible on the surface of the eye, most commonly in the upper-outer region.
Posterior staphylomas, which form at the back of the eye, are far more common and more clinically significant. They involve a localized stretching of the back wall, and because this is where the retina and the nerve-rich center of vision (the macula) sit, they carry a much higher risk of vision loss.
Types Based on Location
Staphylomas are classified into five categories by where they sit on the eye: anterior (at the front, involving the cornea or nearby sclera), intercalary (at the junction between cornea and sclera), ciliary (just behind that junction), equatorial (around the widest part of the eyeball), and posterior (at the back). Posterior staphylomas are by far the most studied because of their strong link to pathologic myopia, a severe form of nearsightedness that causes progressive eye damage.
Among posterior staphylomas, a simplified classification system groups them by the shape and position of the bulge. The wide macular type, where the outpouching covers a broad area around the center of vision, accounts for about 74% of all posterior staphylomas. The narrow macular type follows at 14%, giving the eye a shape sometimes compared to a strawberry on 3D imaging. Inferior and nasal types are rare, making up just 3% and 2% respectively.
Causes and Risk Factors
The dominant cause of posterior staphyloma is pathologic myopia. In severely nearsighted eyes, the eyeball is abnormally elongated, and the sclera at the back becomes progressively thinner and weaker over time. The prevalence of posterior staphyloma in highly myopic eyes varies widely across studies, from 19% to 90%, depending on how strictly it’s defined and the population examined. Posterior staphyloma is considered the hallmark of pathologic myopia, meaning its presence is one of the defining features that separates ordinary nearsightedness from the disease form.
Anterior staphylomas typically result from different causes: severe infections, inflammatory conditions affecting the sclera (scleritis), trauma, or surgical complications that weaken the front wall of the eye. Any process that damages or thins the sclera enough can set the stage for bulging.
What It Feels Like
Posterior staphylomas don’t cause pain. The primary symptom is progressive vision loss, which can take several forms. You might notice blurred central vision that corrective lenses can’t fully fix, distorted or wavy lines when looking at straight objects, or a gradual decline in the sharpness of your best-corrected vision. These changes tend to worsen over years rather than appearing suddenly. Anterior staphylomas, by contrast, may be visible as a dark bulge on the surface of the eye and can cause discomfort or cosmetic concern in addition to visual changes.
Because posterior staphylomas develop slowly and often in eyes already affected by high myopia, many people attribute their worsening vision to their nearsightedness alone. The staphyloma itself may go undetected until imaging reveals the structural deformity.
Complications That Threaten Vision
The real danger of a posterior staphyloma lies in what it does to the delicate tissues stretched over the bulge. As the eye wall bows outward, it pulls and strains the retina, the layer of light-sensitive cells responsible for sight. This mechanical stress triggers a cascade of complications.
Research published in the American Journal of Ophthalmology found a direct linear relationship between the severity of a staphyloma and several forms of damage: breaks in the tissue beneath the retina (lacquer cracks), loss of the pigmented layer that nourishes the retina, and patches of tissue death (chorioretinal atrophy) all increased as staphylomas progressed. The staphyloma also commonly causes the retinal layers to split apart, a condition called foveoschisis, and can lead to macular holes with or without retinal detachment. These macular holes behave differently from the kind that develop in normal-length eyes, precisely because the staphyloma changes the mechanical forces at play.
One surprising finding: eyes with the shallowest staphylomas (the mildest grade) actually showed the largest drop in visual acuity and the greatest frequency of abnormal blood vessel growth and hemorrhages. This suggests that even early-stage staphylomas warrant close monitoring, not just advanced ones. In nearly all cases, the appearance of a staphyloma eventually leads to some form of macular disease, whether from tissue thinning, abnormal pulling forces, or new blood vessel growth.
How Staphylomas Are Detected
A standard eye exam with dilation can raise suspicion of a posterior staphyloma, but confirming and characterizing it requires imaging. Ultrasound (B-scan) can show the outward bulge of the eye wall. Optical coherence tomography (OCT) reveals the thinning of the retina and any splitting of its layers. More recently, 3D MRI has allowed researchers to map the full shape of the eye and detect deformities that aren’t visible on standard imaging, including bulging at the equator of the eye that may be related to the pull of the eye muscles.
Part of the diagnostic challenge is that clinicians have historically used the term “staphyloma” loosely, applying it to any abnormal shape in the back of a highly myopic eye even when there’s no true outpouching. A precise definition requires demonstrating that the curvature of the bulge is sharper than the curvature of the surrounding eye wall.
Treatment Options
There is no way to reverse a staphyloma once it has formed. Treatment focuses on two goals: slowing further progression of the underlying eye elongation and managing the complications that arise.
For slowing myopia progression (and therefore potentially limiting staphyloma worsening), atropine eye drops are the most effective conservative option, followed by specialty contact lenses designed to alter how light focuses on the peripheral retina. Standard soft contact lenses, rigid gas-permeable lenses, and undercorrected glasses have not been shown to slow progression.
The only surgical approach that directly addresses the elongation of the eye is posterior scleral reinforcement. First proposed in 1930, this procedure involves placing biological or synthetic material over the weakened back wall of the eye to physically prevent further stretching. It remains the only surgical method shown to be effective at stopping the eye from getting longer, though it cannot shrink an eye that has already elongated. It’s sometimes combined with patching therapy in young children with high myopia in one eye.
When complications like abnormal blood vessel growth develop within a staphyloma, injections that block the growth signal for those vessels can help maintain vision. A study tracking patients over four years found that eyes with this type of vessel growth maintained their vision with an average of about nine injections over that period, while eyes that developed fluid leakage without vessel growth actually lost vision spontaneously over the same timeframe. In both groups, baseline vision was the strongest predictor of where vision would end up four years later, reinforcing the importance of catching complications early.
Long-Term Outlook
Staphyloma is a progressive condition. Vision tends to decline over years to decades, and the rate of decline depends largely on which complications develop and how quickly they’re treated. Eyes with posterior staphylomas consistently show reduced best-corrected visual acuity compared to myopic eyes without them, and the staphyloma itself determines the severity of associated macular disease.
The practical takeaway is that staphyloma is not simply “bad nearsightedness.” It represents structural damage to the eye wall that changes the mechanical environment for every tissue inside the eye. People with high myopia who notice worsening vision despite updated prescriptions, or who develop distortion in their central vision, are the ones most likely to benefit from the specialized imaging that can detect a staphyloma and guide timely treatment of its complications.