Intraocular Foreign Body

What is Intraocular Foreign Body?

Ocular injuries, which are injuries to the eye, are a major cause of blindness and continue to be a global health concern. One common eye injury is the intraocular foreign body (IOFB), which usually occurs in young adults. An IOFB is most often a metallic object that enters the eye due to activities like hammering, drilling, or in extreme cases, gunshots and bomb explosions. These injuries are especially common among manual laborers.

These foreign objects can get stuck anywhere within the eye, either in the front or the back. Because they’re usually sharp and move with high speed, they’re mostly found lodged in the back of the eye. A study found that about two-thirds of IOFBs were located in the back of the eye. Thanks to advancements in surgical techniques, many of these injuries can be treated successfully, and good vision can be restored.

However, how well someone can see after the injury depends on several factors. These include the size and location of the foreign object, what the foreign object is made of, how much damage it has caused, how long it’s been since the injury, and whether there are any related complications like inflammation or detachment of the retina.

What Causes Intraocular Foreign Body?

Hammering is the activity that most commonly leads to injury. One study found that hammer-related incidents accounted for 43% of injuries, while metal cutting was responsible for 19%. Additionally, chiseling and drilling incidents made up 10% of injuries, gardening was the cause of 5%, falling from a height accounted for another 5%, and the cause was unknown for 14% of injuries. In regions affected by conflict, injuries from firearms and blasts are also common.

Risk Factors and Frequency for Intraocular Foreign Body

In the United States, about 2.4 million people experience eye injuries every year. Injuries involving foreign bodies inside the eye (IOFBs) make up 17 to 41% of serious eye injuries, known as open globe injuries. These injuries are most common amongst young men who work at home, although these only comprise a small portion (13%) of all such injuries. The jobs that see these types of injuries occur most frequently are among workers and farmers; this is because they’re involved in activities such as hammering, drilling, chiseling, and shoveling that tend to kick up foreign bodies.

In the United Kingdom, the yearly rate of IOFBs is roughly 0.16 per 100,000 people. Shockingly, only 0.77 to 6% of those with an IOFB were wearing protective eyewear at the time of injury. This emphasizes the importance of implementing and following proper safety measures at work.

Signs and Symptoms of Intraocular Foreign Body

When a foreign object gets into the eye, the patient might not always feel pain or discomfort immediately. They might just feel like something’s hit the eye, followed by a blurry vision, or in some cases, no symptoms at all. If you’ve suffered a blow to the eye, especially through blasts or firearms which may result in tiny splinter-like injuries, it’s essential to get a checkup. It’s also important to report if only one or both eyes were impacted, due to the legalities and possible financial compensation if any foreign bodies are missed during the evaluation.

A thorough eye exam will help find any external injuries or foreign bodies that might have affected the eye. They will assess your eyesight, looking for any changes between your initial eye sight and after correction. An examination instrument called a slit-lamp will be used, which can help find abnormalities like cuts in the eye tissues, bleeding, and the foreign body’s entry site. If present, some pigment under the conjunctival membrane (covering the front of the eye) could point towards a risk of the deeper eye layers being pushed out through a breach, and show the possible site of the foreign object entering the eye. They will also check if the cornea (outer surface of the eye) has been punctured.

They will also carry out tests to check the nature and size of damage, and if the iris (coloured part of your eye) is affected or not. Any changes in the colour of your iris could mean a longstanding issue. The examination will help find the location of the foreign body, as well as check for any damage or changes to the lens of your eye. This could include presence of pigment, cloudy patches, signs of cataract, a torn lens covering, or any unusual movement of the lens.

They will also perform gonioscopy, which will check for any pigmentation or scarring in the anterior chambers (front part) of the eye, and the location of the foreign body, especially in the lower corner. The eye pressure will be measured but in cases with a clear eye injury, applying pressure on the eye will be avoided as it may push out the inner eye contents. Most foreign bodies preferentially end up in the posterior segment (back part) of the eye.

Finally, with the help of dilation, the back of your eye will be checked for signs like the foreign body’s site of impact and presence of fibrous cover over it, which is often formed around it, and any pigment changes in the surrounding area. Long-term issues can also lead to optic nerve damage. In cases where your eye’s inner parts are not clear due to clouding of the lens, bleeding inside the eye or inflammation, an ultrasound will be done to find the location and size of the foreign body.

Testing for Intraocular Foreign Body

Finding and pinpointing foreign objects within the eye is incredibly important. Things like taking detailed pictures of the eye using a specialized medical camera can be useful in understanding the problem and explaining the situation to the patient.

X-rays of the eye from different angles can detect metallic objects but may not see things like wood or glass. If there are multiple metallic objects, X-rays can identify them. X-ray pictures can also be used to figure out where these are in the eye through various methods of calculation and techniques, which involve the person moving their eyes in certain ways and noticing how the objects inside move too. For example, if the object moves in the same direction as the eye, it’s likely in the front part of the eye. If it moves in the opposite direction, it’s probably in the back part.

An ultrasound scan of the back part of the eye (B scan) is affordable and helpful to identify metallic objects. Different materials will appear differently on the ultrasound scan. For example, metallic bodies appear as bright structures with specific patterns on the ultrasound, while glass and plastic objects may appear different depending on their optical properties. However, an ultrasound B scan should be avoided if the eye is already damaged as it could potentially make things worse.

A CT scan can accurately figure out the number, size, shape, and location of a foreign body in the eye. The type of foreign object can be identified based on its appearance in the CT scan. For example, wooden objects have a low intensity with no artifact, plastic has moderate intensity with no artifact, and metallic objects have high intensity with specific artifacts.

An MRI scan is highly sensitive and can find organic and glass objects more effectively. However, it’s not safe to use an MRI if the foreign object is made of metal as it could potentially cause it to move and further harm the eye.

There are other imaging techniques that can be used to find a foreign body in the eye, such as Ultrasound Biomicroscopy (UBM) and Anterior Segment Optical Coherence Tomography (AS-OCT). However, each technique has its limitations and should be used with caution in certain cases like open eye injuries.

Patients who have had a metallic foreign object in their eye for a long period might show changes in their eye function tests. For example, patients with iron objects could eventually show reduced photoreceptor function. Therefore, preoperative eye function tests are necessary to predict the patient’s chances of visual recovery after surgery to remove the foreign object from the eye.

Treatment Options for Intraocular Foreign Body

Surgery for an eye injury aims to repair the damage and restore the eye’s structure as much as possible. If the retina is detached or there is an infection within the eye, the chances of recovering sight are often low. Before surgery, a CT scan should be performed to find the location of the foreign body within or outside the eye.

The injured eye should be carefully protected and handled, avoiding any pressure that could force the internal parts of the eye out. It’s essential to give a tetanus shot and clean the affected area with a sterile solution. If the wound is on the surface and there is no serious eye damage, small foreign bodies could be removed. It is also advisable to consider giving antibiotics to prevent infection within the eye, which is a common complication.

Foreign bodies made of iron and copper need to be removed as quickly as possible since they react easily with eye tissues. Stainless steel and aluminum foreign bodies are more tolerable, while organic matter and stones often carry a high risk of infection, so it’s crucial to remove them right away.

Before the operation, the position of the foreign body should be determined. The surgery begins with fixing the damaged part of the cornea and/or the white part of the eye called the sclera. The focus is to ensure that the repaired part doesn’t leak at the end of the surgery.

Different strategies are used depending on the foreign body’s location. If it’s in the front part of the eye, the damaged cornea or sclera is sealed, and any debris or blood clotting in this area is washed away. Small, mobile foreign bodies can be removed with specialized tools. A separate cut is made for its removal, not using the original injury site.

If the foreign body is stuck within the lens of the eye, and the lens is damaged, the entire lens might need to be removed along with the foreign body. In cases where there’s a chance the lens or foreign body may fall into the jelly part of the eye, it’s always best to approach this with caution and with proper preparation.

If the foreign body is found in the angle of the front part of the eye, a procedure called gonioscopy is done to remove it. If the foreign body is in the back part of the eye, surgery will allow for clear visualization and removal.

After removing the foreign body, preventive treatment should be done at the site of impact. If a retinal detachment is present, further surgery should be done to reattach it. All loose ends of the surgery incision should be closed tightly.

What else can Intraocular Foreign Body be?

A foreign body in the eye, also known as an IOFB, is typically identified based on symptoms and medical history. Sometimes, minor incidents causing the injury might not be remembered or mentioned by the patient. Years later, they may show signs of siderosis, a condition that can look similar to certain eye diseases like retinitis pigmentosa. This disease causes discoloration of the eye disc and degradation of the retinal pigment.

Chalcosis, a condition caused by copper deposits in the eye, can also occur in some cases. These deposits can be seen around the circumference of the cornea, in the eye’s protective membrane. This may result in a visible ring around the cornea, similar to what happens in Wilson’s disease. Sometimes, patients may develop so-called sunflower cataracts. The interior of the eye, called the vitreous, may also appear clouded due to tiny, dust-like particles. A CT scan can help detect a small foreign body in such instances. But if it’s retinitis pigmentosa, these signs won’t be present.

In some cases, the patient might have an old IOFB wrapped in fibrous tissue in the peripheral area of the retina, making it look like an eye condition called Toxocariasis granuloma. Toxocariasis mainly affects young children who’ve been in close contact with puppies. But a thorough conversation about the patient’s past injuries can often help rule out this possibility.

What to expect with Intraocular Foreign Body

The future outlook or prognosis of a condition called intraocular foreign body (IOFB) relies on several factors. These include the timing of treatment, the initial vision when treated, the extent of the injury, the location of the foreign body, the type of injury, and certain accompanying features.

Patients who seek help early usually have a better chance of retaining their vision. However, late treatment, especially in cases where the foreign body is iron, can result in a condition called siderosis and a poor prognosis. Also, if a patient’s vision is good at the time of treatment, they generally have a brighter future outlook.

The severity of the injury also matters. For example, a small hole in the sclera, which is the white part of the eye, leads to a good prognosis. But if there’s a hole in the center of the cornea, it could result in scarring, impaired vision, and a poor prognosis.

The location of the foreign body is important too. If it’s in the front part of the eye, the prognosis is generally better compared to foreign bodies located in the back of the eye. Damage such as a ruptured eye globe and penetrating injuries generally give a worse prognosis. The presence of certain conditions, like defective pupil reaction to light, bleeding in the front chamber of the eye, bleeding in the jelly-like substance inside the eye, retinal detachment, and infection inside the eye also imply a poorer visual outcome.

An Ocular Trauma Score (OTS), a system developed in the early 2000s, can help predict the final vision of an injured eye. It uses initial vision and eye conditions (like eye globe rupture, penetrating injury, retinal detachment, and defective pupil reaction to light) to score the severity of injury. After gathering scores for each condition, a total raw score is calculated which can help foresee the patient’s final vision.

Possible Complications When Diagnosed with Intraocular Foreign Body

Injuries to the front part of the eye can result in various problems like corneal scarring, traumatic cataract, iris defect, hypopyon, hyphema, and open-angle glaucoma. Also, foreign bodies inside the back section of the eye can lead to serious ailments like inflammation within the eye (endophthalmitis), retinal detachment, abnormal growth inside the eye (proliferative vitreoretinopathy), and shrunken, non-functional eye (phthisis bulbi). Damage to the optic nerve or siderosis can manifest in optic neuropathy. In 0.5% to 2.0% of cases, a condition known as sympathetic ophthalmitis has been detected.

The presence of foreign bodies inside the eye results in infectious endophthalmitis in 7 to 13% of the cases on an average. If treatment is delayed for more than 24 hours, the risk of getting infectious endophthalmitis becomes even higher. Aging has also been linked to an increased risk of endophthalmitis in cases of intraocular foreign bodies. Early surgical intervention to remove gel-like substance from the eye (vitrectomy) improves functional vision in 25 to 51% of patients. Even in other cases, it can help to save the eye, though may not improve vision. Patients should be made aware of the risks connected with IOFB, including potential phthisis.

Potential Eye Problems:

• Corneal scarring
• Traumatic cataract
• Iris defect
• Hypopyon
• Hyphema
• Open-angle glaucoma
• Endophthalmitis
• Retinal detachment
• Proliferative vitreoretinopathy
• Phthisis bulbi
• Optic neuropathy
• Sympathetic ophthalmitis
• Infectious endophthalmitis (in case of foreign bodies)

Preventing Intraocular Foreign Body

An Intraocular Foreign Body (IOFB) is capable of causing loss of vision that cannot be restored, so patients need to take steps to protect themselves. Patients need to be properly advised about what IOFB could mean for them in the long run and why it’s so crucial to keep having regular check-ups.