What is Asteroid Hyalosis?
Asteroid hyalosis (AH) is a condition characterized by the presence of shiny yellow-white particles, known as asteroid bodies (ABs), within the clear gel (vitreous) that fills the eye. Originally named “asteroid hyalitis” by Benson in 1894, it was later renamed asteroid hyalosis as there’s no inflammation involved. Another term used to describe it is “Scintillatio albescens or ‘nivea”, introduced by Wiegmann in 1918.
These asteroid bodies look like stars (asteroids) in the night sky, hence their name. Generally, AH doesn’t require treatment, as it’s a harmless clouding of the vitreous. Yet, it’s still important for an accurate diagnosis to be made. Studying the eye-related and whole-body features associated with AH, as well as understanding how it develops, and its biochemical composition, are also worth discussing.
What Causes Asteroid Hyalosis?
The exact cause of a condition known as asteroid hyalosis is currently not known.
echoes in the vitreous cavity and a clear zone between the dot echoes and the
retina.
Risk Factors and Frequency for Asteroid Hyalosis
Asteroid hyalosis is a condition found in about 0.8% to 2.0% of adults, according to various studies. The rate tends to increase with age. In fact, autopsy studies have found it present in 3.2% of individuals aged 61 to 70 years, and in 6.6% of those aged over 91 years. Most of the time (in 75 to 90% of cases), the condition affects only one eye. There is no evidence to suggest that any particular race is more prone to it. While some research suggests more men have it than women (a 2 to 1 ratio), other studies have found no difference between genders. It’s worth noting that Asteroid hyalosis is not inherited, and cases within families are rare.
- Asteroid hyalosis affects 0.8% to 2.0% of adults.
- The incidence increases with age. It’s seen in 3.2% of people aged 61 to 70 years, and 6.6% of those over 91.
- A majority of cases (75 to 90%) affect one eye.
- There’s no race that is more prone to the condition.
- Some studies suggest it’s more common in men, but others found no gender difference.
- Asteroid hyalosis is not passed down through families, and cases in the same family are rare.
Signs and Symptoms of Asteroid Hyalosis
Asteroid hyalosis (AH) is a condition that some research suggests might be related to systemic diseases like diabetes mellitus (DM), high blood pressure, and high cholesterol, but the evidence so far has been mixed and conclusive results are yet to be confirmed. For instance, a study by Smith and colleagues found that 70% of patients with AH also had diabetes, but their study didn’t include a control group for comparison.
Moreover, another study by Luxenberg and Sime found no significant difference in AH occurrence between diabetes patients and a control group. In a larger study by Bergren and co-authors comprising 12,205 participants, around 29% of the 101 patients with AH had a history of diabetes, a rate significantly higher than the 10% prevalence in the control group. The difference was statistically significant.
However, Fawzi and colleagues, in their study that revolved around examining 10,801 human eyes after death, found no significant association between DM and AH. Additionally, the fact that AH often occurs in one eye despite being a systemic disease such as DM provokes questions about how strongly these conditions are associated.
Links between AH and other conditions like high blood pressure, atherosclerosis, and high cholesterol have not been consistently proven in large-scale studies, although smaller studies have also suggested possible links with high cholesterol, high levels of calcium in the blood, and gout.
Testing for Asteroid Hyalosis
Patients suffering from asteroid hyalosis often don’t show symptoms and are generally diagnosed during routine eye check-ups. Although the tiny lumps in these patients’ eyes can disrupt some light, they typically scatter only a little because of their smooth surface. Only when such particles come very close to the macula (the small area in our retina that helps see details), or if they bunch up behind the lens due to posterior vitreous detachment, they might cause vision problems. In such rare cases, surgery might be required to remove the vitreous—a jelly-like substance filling the space in the middle of the eye.
When looked at using an ophthalmoscope, these lumps appear to be attached to strands in the vitreous and move with the eye movements, only to return to their original position once the eye is still. When observed, these small particles range from 3 to 100 microns in size, and they can make it challenging for the observer to get a clear view. In order to get a better view, a technique called direct ophthalmoscopy is used, as it reflects less light compared to other methods.
Moreover, if a patient suffers from asteroid hyalosis as well as diabetes-related eye issues, they might need a specific medical imaging test to detect any new blood vessels in their eyes. Current technology allows for a wider scope of these tests that can also identify even peripheral lesions, such as tumors. There are safer techniques being developed with the same purpose. Optical coherence tomography angiography is one such test that has proven helpful in the detection of diabetes-related eye issues. Furthermore, optical coherence tomography is also useful in studying the vitreoretinal interface—where the vitreous gel and the retina touch—in these patients. However, Swept source-OCT is a preferred method due to its superior diagnostic abilities in such cases.
Patients with asteroid hyalosis are also found to have undetached vitreoretinal interfaces more frequently. Some studies suggest that this attachment might be the cause of the lumps. Additionally, asteroid hyalosis is less commonly observed in nearsighted eyes compared to farsighted ones. Infrequent incidents of retinal detachment are reported in the case of asteroid hyalosis. Other less reported eye issues related to asteroid hyalosis include retinitis pigmentosa, uveal melanoma, and pre-Descemet dystrophy.
Treatment Options for Asteroid Hyalosis
Asteroid hyalosis, a condition that affects the eye, usually doesn’t cause any symptoms and only requires monitoring. However, it’s important not to overlook other potential eye problems when examining the back of the eye, which may be challenging due to this condition. Certain special eye scans like fluorescein angiography can help identify new blood vessels in the eye, which can occur with asteroid hyalosis and diabetic retinopathy. Other detailed eye scans such as optical coherence tomography and B scan ultrasound can help identify any irregularities on the surface of the retina or detect any hidden growths.
Cataract surgery can be more challenging if you also have asteroid hyalosis. Surgeons should be aware of the following potential issues. First, the eye scan may mistakenly show that the length of the eye is shorter than it actually is due to echoes from asteroid hyalosis. Comparing this with the length of the other eye can be useful. Second, the reflections caused by asteroid hyalosis can make it difficult to see the back of the lens capsule during surgery. Finally, surgeons should avoid using a silicone lens implant in these cases because the material can cause buildup of calcium and phosphorus from asteroid hyalosis on the back surface of the lens. While these deposits can be successfully removed using laser surgery and a special eye surgery called pars plana vitrectomy, replacing the lens implant is usually the preferred treatment option in these scenarios.
There are some circumstances where a surgery to remove the vitreous, the jelly-like substance in the middle of your eye (vitrectomy), may be needed when you have asteroid hyalosis. These include difficulty in seeing the back of the eye and the failure of special eye scans to identify the cause of vision symptoms, inability to perform laser treatment for diabetic retinopathy, difficulty finding tears in the retina in the presence of a detached retina, and in rare cases, vision symptoms such as floaters or decrease in visual acuity.
What else can Asteroid Hyalosis be?
When medical professionals diagnose Asteroid Hyalosis, a condition affecting the eye, they also need to consider look-alike conditions, including:
- Synchysis Scintillans, which typically happens in eyes affected by advanced or degenerative disease and is marked by cholesterol crystals moving freely and settling in the jelly-like substance in the eye (the vitreous).
- Amyloidosis of the eye, usually affecting both eyes, causing noticeable problems with vision. The only way to confirm this condition is through a laboratory examination of an eye tissue sample.
- Vitritis, a condition characterized by inflammation inside the eye. It is mostly associated with blurry vision and other symptoms such as pain, redness, and a history of similar issues.
- Old vitreous hemorrhages, which are a result of bleeding into the vitreous. This needs a thorough examination to identify possible causes like injuries to the eye, problems with blood vessels in the retina, or retinal tear.
- Eye malignancies such as lymphoma, which can be identified through laboratory examination of an eye tissue sample.
This is particularly important when diagnosing other conditions that Asteroid Hyalosis can mimic, like retinoblastoma, a type of eye cancer that usually affects children. When such complication arise, a specific set of procedures for managing retinoblastoma should be executed.
What to expect with Asteroid Hyalosis
Asteroid hyalosis typically doesn’t cause symptoms and therefore usually has a good prognosis. However, if other eye diseases like diabetic retinopathy are present, the outcome depends on these associated conditions. Similarly, if asteroid hyalosis is concurrent with conditions like retinal detachment without a noticeable break, or bothersome floaters – small moving spots that appear in the field of vision – it may require a procedure called vitrectomy.
The prognosis in such cases would then depend on these added conditions. When it comes to cataract surgery, thorough and careful biometry – the measurement of the eye – is essential. Accurately estimating the power of the intraocular lens prior to surgery can lead to better outcomes for patients with asteroid hyalosis undergoing cataract surgery.
Possible Complications When Diagnosed with Asteroid Hyalosis
Asteroid hyalosis is a condition that doesn’t usually lead to any complications. Nevertheless, some individuals might have denser than usual asteroid hyalosis, which can result in bothersome specks or ‘floaters’ in their field of vision. In such instances, a medical procedure known as vitrectomy might be necessary. Additionally, asteroid hyalosis located in the front part of the vitreous – a jelly-like substance that fills the back part of the eye, can lead to reflections during cataract surgery. Being aware of this potential issue can help surgeons prevent complications during the procedure.
Preventing Asteroid Hyalosis
Patients who have diabetes and a condition known as asteroid hyalosis need to be aware of the importance of a special eye test called fundus fluorescein angiography. This test is particularly necessary in cases where there might be new blood vessels growing abnormally in the retina, which could signal an advanced type of diabetic eye disease called proliferative diabetic retinopathy. Early detection and treatment of this condition is crucial to manage its progression.
