The eye is one of the most commonly injured organs in our body at a rate of 10%. 1% of all humans experience at least one eye injury in their lifetime.
Picture 1: A severe retinal injury after the accident (scar development)
WHAT ARE THE TYPES OF EYE INJURIES?
A closed globe injury is when the eye wall is intact but the intraocular tissues are harmed depending on the severity of the impact. An open globe injury happens when the ocular integrity is disrupted by a sharp object and a rupture occurs.
WHAT KIND OF DAMAGES MAY HAPPEN IN CLOSED GLOBE INJURIES?
Big objects that firmly hit the eye may cause serious damages without rupturing the eye. In such cases, contractions in the anterior-posterior axis and enlargement in the equator may happen. Then, the eye reverts back to its normal shape. These sudden changes in shape may cause serious damages in the eye. Combined with the movement of intraocular fluid, a series of pathological disorders such as retinal edema, retinal pigment epithelium, intraocular hemorrhage, retinal tears and dialysis may occur at the front and back of the eye, outside the direct area of trauma.
HOW DOES RETINAL EDEMA HAPPEN?
Retinal edema happens in both the area of impact and also the back of the eye. The affected portion of the retina will appear white due to the accumulation of fluid between the tissues. At the beginning, the vision is significantly affected because of the edema at the back of the eye. Depending on the severity of the edema, everything may go back to normal in a few days, or in more severe cases permanent loss of vision may take place. Edema at the back of the eye may cause a late-term rupture which is called a macular hole and causes severe loss of vision.
HOW DOES INTRAOCULAR HEMORRHAGE HAPPEN?
Hemorrhage due to a closed globe trauma at the rich vascular structure of the eye fills the vitreous cavity. The coagulation it creates there takes sometimes months to clear. A hemorrhage that fails to clear for a long time is followed up by ultrasonography. If a retinal tear appears on ultrasound, then an emergency vitrectomy is performed.
DO CLOSE GLOBE TRAUMAS CAUSE RETINAL DETACHMENT?
Thirty-five percent of retinal detachments with a tear are trauma-based whereas about 50% of traumatic retinal detachments are due to blunt traumas. Two kinds of retinal tears form as a result of an impact on the eye:
1-) The retinal damage at the site of impact first creates a sudden retinal edema. In some cases, after the formation of retinal edema, the retinal tissue dies and a quite large tear appears. Such tears are usually observed at the lower and outer side of the eye where the eye most frequently gets an impact.
2-) Another type of retinal tear formation is indirect retinal tear. The trauma causes the flexible eye globe to change its shape resulting in varying types and sizes of retinal detachments such as dialysis or giant retinal tear.
Following the formation of the retinal tear, a retinal detachment may occur by the introduction of vitreous fluid in the subretinal space. However, the majority of eye traumas happen to young people in whom the vitreous maintains its gel-like features, therefore at the beginning, there is usually no vitreous fluid that would pass behind the retinal tear. Thus, in young people, retinal detachment develops at a longer period of time than in advanced age. All traumatized cases should be given an early-stage detailed retinal examination by dilating the pupil in order to detect retinal tears and dialyses that precede the development of retinal detachment and to have the opportunity to perform preventive treatment such as laser or cryopexy (freezing treatment). If retinal detachment has already formed, depending on the condition of the tear, scleral buckling surgery or vitrectomy is performed.
HOW DO OPEN GLOBE INJURIES FORM?
For an open globe injury to happen, the integrity of the eye wall must be disrupted by a sharp object. Open globe injuries are usually caused by sharp objects which disrupt the integrity of the eye wall and let the intraocular tissues contact with the extraocular area. Some open globe injuries are hard to identify as they are covered with a thin membrane called the conjunctiva. Low intraocular pressure, subconjunctival edema and hemorrhage may be the symptoms of a concealed open globe injury. Some extremely fast objects strike the eye and then exit at the back of the eye. Such accidents called perforating traumas are more severe. In open globe injuries, the risk of retinal detachment and proliferative vitreoretinopathy (PVR) is almost always present. In PVR, the front part of the retina and the subretinal area are covered with a very intense membrane that prevents the retina from remaining attached. The retina gradually breaks and the injured patient may lose his/her vision completely.
IN WHICH DISEASES IS RETINAL DETACHMENT A BIGGER RISK?
The risk of formation and recurrence of retinal detachment is higher in eye injuries that extend towards the back of the eye globe, in intraocular infections, perforating eye injuries and concealed injuries that extend to the back of the eye.
In most of such cases, vitrectomy is required in order to remove all the membranes at the back and front of the eye. There are different views as to when vitrectomy should be performed but the most common view denotes the first two weeks after the trauma. Such timing will prevent PVR, i.e. complete formation of membranes at the front part of the retina and in the subretinal area, and enable safer surgery. As the time passes, the risk of membrane formation will be higher.
DOES RETINAL DETACHMENT RECUR?
The detachment recurrence rate is very high in open globe injuries. The membranes removed in the first operation may recur in the upcoming weeks. The risk of retinal detachment recurrence is much higher in trauma patients than non-trauma ones. In some cases, the treatment lasts for years. There are patients who have gone through up to 10 operations.
DOES OCULAR INFECTION HAPPEN IN OPEN INJURIES?
After eye injuries, a severe intraocular infection called endophthalmitis in which all ocular tissues are infected by microorganisms, may develop at a rate of 3 to 30%. The risk of endophthalmitis increases in parallel to the contamination level of the object causing the injury.
The power of the bacteria causing the infection determines the onset and the severity of the infection. The worst infections are observed in injuries that happen in rural settings. Injuries caused by objects mixed with wood and soil may cause very powerful microbes to settle in the eye. In such cases, the expedited closure of the open globe wound and the use of antibiotics for the prevention of microbial reproduction are crucial. Very strong antibiotics are currently available that can prevent microbial reproduction when intraocularly injected.
However, in some cases, despite preventive treatment, microorganisms continue to reproduce and a very severe intraocular infection called endophthalmitis begins. The key treatment method in severe endophthalmitis cases is vitrectomy in which the microorganisms and toxins that cause the infection are washed out from the vitreous cavity. Prompt vitrectomy is an effective treatment of endophthalmitis in many cases.
WHAT SHOULD BE DONE WHEN A FOREIGN BODY ENTERS THE EYE?
The majority of the foreign bodies (FBs) entering the intraocular space are metallic or magnetic. FBs that stay in the eye for a certain period of time may create significant side effects. Especially organic FBs may cause infection and even endophthalmitis.
The likelihood of developing intraocular reactions against FBs involving iron and copper is very high, therefore such FBs must be immediately removed after soothing the eye. Copper-involving FBs may cause very intense infections that might create suspicions of endophthalmitis. At the chronic term, a situation called chalcosis is formed which is characterized by the deposition of copper into the cornea (Kayser-Fleischer Ring), the lens (sunflower cataract) and other tissues. The chronic toxicity in ocular tissues caused by iron and its alloys is called siderosis. Iron affects almost all the tissues in the eye. A situation characterized by color change in the iris, glaucoma, iron deposits at the anterior lens capsule and retinal pigmentary retinopathy may develop. In ERG tests, a distinct reduction in the a-waves and b-waves is observed. The treatment approach is determined after the accurate identification of the typical shape, localization and size of the FB.
ARE ALL KINDS OF FOREIGN BODIES REMOVED FROM THE EYE?
It is not absolutely necessary to remove an FB from the eye. Inert FBs not causing secondary effects may be left in the eye as long as an intervention is not required for another reason. Such patients should be under lifelong ophthalmologic follow-up. However, dangerous FBs such as iron or copper must be removed in order to prevent related reactions.
HOW TO REMOVE A FOREIGN BODY
In general, if an FB is to be removed, the process will be performed either during the course of the first repair or after the repair. An FB will be immediately removed if endophthalmitis exists which may cause the loss of the eye. Other FBs may be removed after a while. FBs at the back of the eye are removed through vitrectomy. Removal of large FBs is very difficult as the probability of developing retinal detachment is very high.