When your optic nerve doesn’t develop all the way, you may not be able to see through that area of your eye. This congenital condition is most often experienced by people who have mothers with diabetes. There’s no treatment or cure.

Superior segmental optic nerve hypoplasia (SSOH), or topless disc syndrome, is a congenital eye condition where a part of the optic nerve is underdeveloped. Your optic nerve is the bundle of nerve fibers that connects your eye to your brain.

Most people with SSOH have mild or no symptoms. The condition is rare, and it’s most often diagnosed in people who have mothers with diabetes. It doesn’t get worse over time, and it’s often discovered at the time of an eye exam for unrelated eye conditions. Normally, this blind spot isn’t noticeable unless you only have vision in one eye or have one eye closed.

Read on to learn more about SSOH including causes, risk factors, and how it may affect your vision.

Your retina is the layer of special cells at the back of your eye that converts light signals into electrical information. This electrical information is carried through a large bundle of nerve fibers called your optic nerve to your brain.

People with SSOH have abnormal development involving one part of the group of nerve fibers missing from the retina. Normally, these fibers would leave the eye through the optic nerve en route to the brain. But that’s not the case with SSOH. No visual signal is transmitted from that affected area — meaning you have a loss of vision in that part of your visual field.

Normally, this blind spot isn’t noticeable unless you only have vision in one eye or have one eye closed.

SSOH was first reported in 1977 when researchers identified 17 cases in children born to mothers with diabetes.

It’s difficult to estimate how often it occurs in a population due to its rarity, and because there’s often a lack of symptoms. It’s usually found during eye exams for unrelated reasons.

The largest studies available estimating its prevalence are from Japan and Korea. In the study from Japan, researchers tested 14,431 people and estimated 0.3% of the study group had SSOH. In the Korean study, researchers tested 5,612 people and estimated 0.24% of them had SSOH.

A type of imaging called optical coherence tomography can help eye doctors look for characteristic signs of SSOH and distinguish it from other conditions such as glaucoma. This imaging test uses waves of light to examine your retina.

SSOH has four characteristic signs:

  1. entrance of the central retinal artery to the upper part of your disc, which is or the beginning of the optic nerve (superior central retinal artery entrance)
  2. paleness in the upper part of your optic disc (superior disc pallor)
  3. halo around the upper part of your optic disc (superior peripapillary halo)
  4. thinning of nerve fibers in the upper part of your disc (superior peripapillary nerve fiber thinning)

People with SSOH may not have any of these features, but their presence helps differentiate SSOH from other eye disorders.

SSOH often causes mild symptoms that don’t affect daily function.

Since your optic nerve carries information between your eye and brain, you won’t receive any visual information to your brain if the nerve fibers are damaged in your optic nerve.

With SSOH, most of your visual field remains intact. But some people with SSOH have impairment of the bottom half of their visual field, since the upper part of the optic nerve can’t transmit information from their retina to their brain.

The effect on vision is often minor and doesn’t affect daily function. This blind spot usually isn’t noticeable unless you only have vision in one eye or have the other eye closed.

People often aren’t aware that they have problems with their visual field, but they may have a history of stumbling or other habits that may suggest problems with their lower vision.

SSOH can occur in one or both eyes.

The condition develops from birth, so if you have it in one eye it won’t spread to the other later in life.

When you’re developing in the womb, your optic nerve contains about 3.7 million nerve fibers. That number drops to 1.1 million by birth through the controlled destruction of unneeded cells. It’s thought that excessive destruction of optic nerve cells may lead to the development of SSOH.

It’s unclear why this reaction is triggered in some people or why only the upper fibers are destroyed.

The strongest risk factor for SSOH is diabetes in the mother. Children of mothers with diabetes are more likely to develop optic nerve hypoplasia.

Optic nerve hypoplasia may also be linked to low birth weight and a history of ischemic heart disease in the father. Some studies report SSOH as more common in people assigned female at birth, but other studies don’t report a sex difference.

You’ll notice that the language used to share stats and other data points is pretty binary, fluctuating between the use of “male” and “female” or “men” and “women.”

Although we typically avoid language like this, specificity is key when reporting on research participants and clinical findings.

Unfortunately, the studies and surveys referenced in this article didn’t report data on, or include, participants who were transgender, nonbinary, gender nonconforming, genderqueer, agender, or genderless.

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Diabetes in the mother, or maternal diabetes, is linked to many issues at birth, including SSOH. Although SSOH is highly associated with maternal diabetes, it can also occur in the absence of diabetes.

Other birth-related issues associated with maternal diabetes include:

  • sacral hypoplasia, where there’s abnormal development of the end of the spine
  • situs invesus, where the organs in the chest and abdomen are mirrored compared with their usual position
  • duplex ureters, where each of the kidneys have an extra tube draining to the bladder
  • renal agenesis, where a person is born with one or no kidneys
  • heart irregularities
  • anencephaly, where a person is born without parts of the brain and skull

SSOH is a congenital condition that’s present from the time of birth and doesn’t get worse with time.

Most people don’t know they have it until they receive imaging for another reason. This is especially true if it only occurs in one eye.

There’s no specific cure or treatment to fix this eye issue. For those who experience SSOH in both eyes, adjusting one’s sightline to see the lower half of the visual field is a workaround.

Some evidence suggests that people with this condition may be more prone to glaucoma, which is damage to your optic nerve and is often associated with chronically elevated eye pressure.

Taking precautions to prevent glaucoma is generally helpful, including getting regular eye exams, controlling your blood pressure, and staying physically active.

SSOH is a congenital condition that causes defects in the upper part of your optic nerve that’s normally occupied by retinal nerve fibers. It’s a nonprogressive condition, meaning it doesn’t get worse over time, and it often doesn’t impact daily function.

SSOH doesn’t require treatment, but it may increase your risk of developing glaucoma. Taking precautions to avoid glaucoma such as controlling your blood pressure and maintaining a moderate weight may help you avoid glaucoma.