Corneal foreign body: clinical guidelines

List of Abbreviations

CGI – closed globe injury

FB – foreign body

CT – computed tomography

ICD-10 – International Classification of Diseases, 10th Revision

OGI – open globe injury

OCT – optical coherence tomography

Terms and Definitions

Open globe injury is a mechanical eye injury with a full-thickness wound of the fibrous tunic (cornea and/or sclera).

Closed globe injury is a mechanical eye injury without a full-thickness wound, maintaining the integrity of at least a very thin layer of the fibrous tunic (cornea and/or sclera) of the eyeball.

Fragment is a synonym for a foreign body

Seidel test is a method for detecting anterior chamber aqueous leakage by instilling a dye into the conjunctival sac during the diagnosis of eyeball wound characteristics

Metallosis is a symptom complex characterizing changes in the eye caused by the toxic effect of a metallic foreign body located within the eyeball or its corrosion products

1. Brief information on the disease or condition

1.1 Definition of the disease or condition

A corneal foreign body is an object foreign to the body that has embedded into the tissue of the cornea. It is a traumatic injury to the cornea which, depending on the depth of the foreign body, can manifest either as a closed globe injury (CGI) if the corneal injury is partial-thickness, or an open globe injury (OGI) if the fibrous tunic of the eye is penetrated full-thickness by the foreign body [1-5]. A corneal foreign body (FB) is classified as superficial if it is located in the epithelium or anterior layers of the stroma, and deep if it is located in the deeper layers of the cornea [6,7,8].

1.2 Etiology and pathogenesis of the disease or condition (group of diseases or conditions)

The main causes of foreign bodies (FBs) entering the cornea in peacetime are accidents (working with metal and stone using various moving machinery without personal protective equipment, domestic accidents, industrial accidents, road traffic accidents, sports, injuries in children, etc.) [3,9,10,11].

If the injury is caused by an explosion (in the mining industry, in combat conditions), both eyes are typically injured with multiple particles of stone, sand, coal, gunpowder, etc. embedding into the fibrous tunic of the eye (cornea and sclera). Such injuries are often accompanied by simultaneous burns of the conjunctiva, cornea, eyelids, and facial skin, as well as ocular contusion [6,9].

The most frequent cause of single superficial foreign bodies entering the cornea is metalworking using a circular saw or an angle grinder ("angle grinder").

In the 1940s, based on a large collection of enucleated eyes containing FBs, a variety of pathogenetic reactions to FB implantation were described, differing in form and severity [10,12,13]. In some cases, an almost areactive tissue behavior in response to foreign body implantation is observed, but such cases are rare. In the majority of cases, the pathogenesis of corneal injury upon FB implantation consists of a series of standard stages: tissue alteration, an exudative phase with edema, demarcating suppuration with tissue lysis, and less frequently—even at early stages—a picture of proliferative phenomena accompanied by perifocal edema and capsule formation. There are differences between anatomical changes immediately following trauma (consisting of tissue alteration and necrosis) and secondary inflammatory reactions (expressed in various phases of inflammation and accompanied by resorption processes, infiltration around foreign bodies, purulent foci, and finally, encapsulation of the foreign body). If the foreign body is not removed from the eye within the next few hours and treatment is not prescribed, the pathological process generally follows the laws of inflammation with the development of exudative and proliferative phases, keratitis, ulceration of the ocular surface, and progression of the inflammatory process into the interior of the eyeball, potentially leading to endophthalmitis if treatment is untimely. The occurrence of a particular reaction to a foreign body is determined by the following factors: chemical activity, size and shape of the fragment, general condition of the body, local tissue reactivity of the eye, etc. [12,13].

A strong inflammatory reaction is caused by organic foreign bodies, such as wood particles, bee sting, plant awns [7,14].

Prolonged presence of a metallic FB leads to specific changes in corneal tissues in the form of metallosis [15].

1.3 Epidemiology of the Disease or Condition

According to both domestic and foreign literature, corneal injuries are frequent and account for about 10% of all initial patient visits for eye trauma [13]. According to the United States Eye Injury Registry (USEUR), the cornea is injured in more than 50% of severe eye trauma cases [16].

Corneal foreign bodies occur in both peacetime and wartime. During the Great Patriotic War, according to N.A. Vishnevsky, among non-penetrating wounds of the eyeball, which accounted for 17.1% of all eye injuries, corneal foreign bodies constituted 52.4% [12]. According to O. Heier, in one of the local wars in the Middle East, 17% of eye injuries were caused by FBs [11].

In peacetime, industrial injuries show a higher frequency of foreign bodies lodging in the cornea compared to the sclera, whereas military shrapnel injuries show the reverse statistics. Thus, according to A.B. Katsnelson and S.I. Smelyansky, the frequency of fragments lodging in the cornea and corneoscleral zone in industrial injuries was 64.6% and 13%, respectively. According to P.Y. Bolgov, in combat shrapnel injuries, the wound was localized in the cornea and corneoscleral region in 35.6% and 12% of cases, respectively [10].

A feature of wartime pathology is the multiplicity of foreign bodies, binocular involvement, combination with injuries to other body areas, and combined nature of the trauma. Such cases are characterized by greater severity and worse functional prognoses [1,5,12].

1.4 Features of Coding the Disease or Condition

T15.0 – Foreign body in cornea

S05.5 – Penetrating wound of eyeball with foreign body

S05.8 – Other injuries of eye and orbit

1.5 Classification of the disease or condition

Corneal foreign bodies can be superficial if they are located in the epithelium or anterior layers of the corneal stroma, and deep if located in the deeper layers of the cornea [8].

According to the classification by B.L. Polyak (1953) [6,7], the founder of military field ophthalmology, eye wounds are divided into non-penetrating and penetrating. Non-penetrating wounds include injuries not accompanied by a full-thickness breach of the integrity of the fibrous tunic of the eye (cornea and/or sclera). Penetrating wounds include injuries with a full-thickness breach of the integrity of the fibrous tunic of the eye. Thus, the majority of corneal foreign bodies encountered in clinical practice belong to non-penetrating corneal eye wounds, and only a small percentage of deep corneal foreign bodies fall into the category of penetrating wounds, specifically penetrating corneal wounds of the eyeball. According to the same classification, a foreign body can be magnetic, non-magnetic, and of undetermined magnetic properties [6,7].

According to the adapted international classification of mechanical eye injuries [2,3,4] as modified by domestic authors [1,5], a corneal foreign body can be classified under Type B Open Globe Injury (OGI)—provided there is a full-thickness corneal wound—while all superficial corneal foreign bodies and deep foreign bodies without full-thickness corneal perforation should be classified under Type B Closed Globe Injury (CGI).

Currently, the Russian Federation also applies the classification of visual organ trauma (including corneal wounds with FBs) by severity (Volkov V.V., Danilichev V.F., Eryukhin I.A., Shilyaev V.G., Shishkin M.M.) [8].

Globe injuries are classified by severity into mild, moderate, and severe. The severity determines the prognosis.

Mild injuries include foreign bodies in the superficial layers of the cornea, do not threaten the patient with a decrease in visual function or a persistent cosmetic defect;

Moderate injuries include foreign bodies in the deep layers of the cornea, but without full-thickness perforation, causing a moderate decrease in function or a mild cosmetic defect;

Severe injuries include foreign bodies with full-thickness corneal perforation, classified as penetrating eye injuries or open globe injuries. They threaten the patient with significant impairment of visual function due to persistent anatomical and functional disorders.

Based on quantity, corneal foreign bodies can be single or multiple.

Complications of corneal foreign bodies:

Inflammatory:

• traumatic keratitis

• traumatic iridocyclitis

• endophthalmitis

Penetration of a foreign body through the cornea into deeper intraocular structures: anterior chamber, lens, vitreous body

Long-term sequelae of corneal foreign bodies

1. Corneal opacity of varying severity, from a barely noticeable nebula to a total vascularized leukoma with pronounced impregnation of the cornea by chemically active multiple foreign bodies [8].

2. Metallosis (siderosis, corneal chalcosis) upon prolonged retention of a metallic foreign body within the corneal stroma [15].

1.6 Clinical presentation of the disease or condition

1. corneal syndrome (photophobia, lacrimation, blepharospasm);

2. superficial injection of the eyeball;

3. edema of the corneal tissues around the site of the foreign body;

4. decreased visual acuity when the foreign body is located in the pupillary area; visual functions are not impaired when the foreign body is located in the peripheral cornea;

5. a foreign body is detected in the superficial layers of the cornea, differing in color and structure from the surrounding tissues

Comments: in mild cases involving a small, chemically inert foreign body, the severity of these symptoms is minimal, and all symptoms resolve within 1-3 days after foreign body removal. If the FB is metallic, there is typically a rust-colored metal oxide ring around the corneal bed for iron foreign bodies, or a greenish ring for copper foreign bodies [6,7,14].

Clinical signs of a deep corneal FB

1. When a foreign body is located beneath the corneal epithelium, corneal syndrome is absent

2. Positive Seidel test in full-thickness corneal perforation, if the wound is not completely tamponaded by the FB;

3. Shallow anterior chamber in corneal perforation;

4. Hypotonia;

5. Hyphema in case of iris damage

Comments: if the foreign body, whether superficial or deep, is infected, delayed or untimely treatment leads to signs of keratitis: increasing edema, appearance of a corneal infiltrate, mucous, fibrinous, and purulent discharge, corneal ulceration, and the possible development of traumatic iridocyclitis, or endophthalmitis in advanced cases, which poses a threat of complete loss of the eye's visual functions [6,7,8,14].Injuries to the cornea caused by a bee sting or a plant awn are dangerous because they feature barbs on their lateral surfaces directed away from the tip. Consequently, any action, even blinking, moves the sting (awn) in only one direction—deeper into the tissue—transforming a superficial FB into a deep one [6,14].

2. Diagnostics, medical indications and contraindications for diagnostic methods

Criteria for establishing the diagnosis/condition:

1. anamnestic data,

2. physical examination

3. instrumental examination

2.1 Complaints and Anamnesis

Comments: in superficial FB, complaints include discomfort, lacrimation, photophobia, eye pain, and decreased visual acuity if localized in the pupillary optical zone. In deep FB localization, signs of corneal syndrome may be absent if the foreign body is located under the epithelium. Decreased visual acuity occurs if localized in the optical zone.

Comments: the history-taking consists of identifying the nature of the damaging agent (metallic, type of metal, wooden, glass, stone, insect sting, circumstances of the injury, scope of first aid provided).

2.2 Physical Examination

Comments: Assessment of the patient's general condition is carried out based on the analysis of appearance, behavior, breathing pattern, pulse, and blood pressure values. It is also necessary to rule out or confirm a concomitant or combined nature of the injury.

2.3 Laboratory Diagnostics

not performed

2.4 Instrumental Diagnostics

Comments: visometry in children under three years of age is performed approximately — determining whether the child has object vision. More precise measurement is possible via the preferential looking test, optokinetic nystagmus recording methods, and visual evoked potentials.

In children aged three years and older, testing is performed using charts: from 3 years of age using a children's silhouette picture chart, from 5 years of age visometry is performed using Landolt rings or "E" tests. Such results are most accurate. In adults, visual acuity is examined using Landolt rings or "E" tests. Examining visual acuity using letters and numbers in astigmatism is the least accurate. The value of visual acuity is taken as the chart row in which all symbols are correctly recognized. In the absence of object vision, light perception and light projection are determined using a direct ophthalmoscope.

Comments: in case of blepharospasm and photophobia, a single instillation of a local anesthetic is performed to facilitate the examination. After instillation, an eyelid speculum may be used for the convenience of examining the eyeball

2.5 Other Procedures

Not required.

3. Treatment, including drug and non-drug therapies, diet therapy, and pain management

3.1 Conservative Treatment

Comments: fluoroquinolones (ATX code S01AE) in drops, in combination with picloxydine - an antimicrobial agent (ATX code S01AX16).

Comments: it is necessary to keep in mind the potential development of allergic reactions: fever, pruritus, rash, arthralgia, anaphylactic shock. Before administering tetanus antitoxin**, anti-shock therapy equipment must be prepared. It is not used if the patient has hypersensitivity (allergy) to any of the components included in the drug.

Comments: topical forms of drugs are prescribed for a prolonged period until complete corneal epithelization occurs.

Comments: prescribed (if well tolerated by the patient) until complete corneal epithelization. It is strictly important to follow the care guidelines and permissible wearing times.

3.2 Surgical Treatment

Comments: superficially located foreign bodies are removed under topical instillation anesthesia. Small foreign bodies located on the epithelium can be removed using a cotton swab moistened with an antimicrobial solution (S01AX Other antimicrobials) – picloxydine (ATX S01X16). Such a procedure can be performed within the framework of primary pre-medical and primary medical care by a non-ophthalmologist.

Comments: the ophthalmologist's right hand is securely fixed on the headrest frame of the slit lamp. The patient's head is also firmly secured in a position comfortable for both the patient and the physician. An optical section makes it possible to visualize the depth of the foreign body in the cornea, allowing precise approach with an instrument while minimizing trauma to the corneal tissue. If there is a rust ring staining around the foreign body (scale) in the corneal tissue, it is carefully removed right after the foreign body, followed by instillation of antibiotic eye drops or application of an antibiotic eye ointment and a bandage. Chemically inert and non-inflammatory foreign bodies located deep in the cornea generally do not require removal. This applies to microscopic particles of coal, sand, glass, stone, gunpowder, and other materials embedded in the corneal stroma that remain without a visible inflammatory response from the eyeball. In the presence of multiple fragments in the cornea located at various depths, one should not attempt to extract too many fragments in a single session to avoid excessive trauma to the corneal tissue. It is advisable to first remove foreign bodies protruding above the corneal surface and scratching the conjunctiva, which cause the patient the most discomfort. Subsequently, a gradual spontaneous migration of deep foreign bodies to more superficial layers is often observed, at which point signs of eye irritation appear, serving as an indication for foreign body removal.

Comments: following local anesthesia (B01.003.004.001) with possible supplementation of infiltration anesthesia (B01.003.004.005), the eye is fixed with forceps or auxiliary bridle traction sutures placed under the rectus muscles or through the episclera. An incision of the corneal layers is made down to the plane of the fragment localization, after which the foreign body is carefully extracted from the incision using the tip of an injection needle. If the fragment is magnetic, it can be removed using a handheld magnet, the tip of which is brought close to the foreign body. It should be kept in mind that even a powerful magnet cannot extract a fragment firmly wedged into the corneal tissue without an incision of the tissue. Extraction is easier if the tissue around the foreign body is softened by an infiltrate. When removing a bee (wasp) sting or a cereal awn, one must remember the complex structure of these foreign bodies. First, the channel in the plane of the sting must be widened using the optical section of a slit lamp, and only then should its protruding end be grasped with pointed-jaw forceps and the foreign body extracted, making sure it slides out easily and there is no risk of it breaking.

The greatest technical difficulties are encountered when extracting a foreign body from the deep layers of the cornea if one of its ends protrudes into the anterior chamber. With such localization, one may attempt to extract it through the wound tract using a magnet without a preliminary incision, since the fragment might otherwise slip into the anterior chamber and damage deeper intraocular structures. If the fragment is non-magnetic, a more complex surgery involving opening the eyeball is required. Several methods for extracting such fragments have been proposed. In all cases, good infiltration anesthesia (B01.003.004.005) or regional block anesthesia (B01.003.004.002) and secure fixation of the eyeball are necessary. Half an hour before surgery, Pilocarpine** (ATC code N07AX01) is instilled into the eye once to constrict the pupil (in adults over 18 years of age). Local anesthesia (B01.003.004.001), infiltration anesthesia (B01.003.004.005), sub-Tenon's or retrobulbar anesthesia (B01.003.004.002 regional block anesthesia) is performed, and the eyeball is fixed with bridle sutures under the rectus muscles. An incision is made in the limbal area along the meridian of the foreign body localization, a spear-shaped knife, spatula, or other fixing instrument is introduced into the anterior chamber beneath the foreign body to prevent it from dropping into the anterior chamber. Next, the corneal tissue over the foreign body is carefully incised and the fragment is delicately extracted with forceps or an injection needle. Only after the foreign body is removed is the instrument withdrawn from the anterior chamber, after which the iris is repositioned with a spatula in case of prolapse and incarceration in the wound. If necessary, the anterior chamber is restored by injecting 0.9% sodium chloride solution**. Suturing of the corneal wound or hydro-sealing by injecting sodium chloride solution** into the thickness of the cornea in the wound area is possible [6,7,14]

4. Medical Rehabilitation and Sanatorium-Resort Treatment

4.1 Medical and Psychological Rehabilitation

As a rule, with rapid removal of a corneal foreign body, the rehabilitation process is fast and does not require the assistance of specialists other than the ophthalmologist, who provides follow-up care until complete recovery.

4.2 Surgical rehabilitation

Surgical rehabilitation of patients with the consequences of severe corneal injuries caused by foreign bodies is recommended to begin 3–6 months after the trauma. Depending on the nature of the post-traumatic corneal changes present, the following surgical interventions are performed:

5. Prevention and Dispensary Observation

Prevention of foreign bodies entering the cornea in everyday life and at work involves compliance with safety rules when operating moving machinery, using protective equipment when processing metals, stone, and wood, and wearing a helmet when riding a motorcycle or bicycle, etc. There is no prevention for criminal injuries.

6. Organization of Medical Care

For a superficial corneal foreign body:

Type of medical care provided:

primary pre-medical healthcare;

primary medical healthcare;

primary specialized healthcare.

Forms of medical care provided: emergency medical care in an urgent form.

Conditions of medical care provided: outpatient.

The procedure for the provision of medical care is regulated by Order of the Russian Ministry of Health No. 902n dated November 12, 2012, "On Approval of the Procedure for Providing Medical Care to the Adult Population for Diseases of the Eye, Its Adnexa, and Orbit."

Phase: acute disease (trauma) of the eyeball.

Average treatment duration (number of days): from 1 to 7 days

Rehabilitation measures: not required

For a deep corneal foreign body:

Type of medical care: specialized, including high-tech care.

Conditions for the provision of medical care: outpatient, inpatient.

Form of medical care: emergency medical care in an urgent form, elective.

The procedure for the provision of medical care is regulated by Order of the Russian Ministry of Health No. 902n dated November 12, 2012, "On Approval of the Procedure for Providing Medical Care to the Adult Population for Diseases of the Eye, Its Adnexa, and Orbit."

Phase: acute disease (trauma) of the eyeball.

Average treatment duration (number of days): the duration of medical care in the ophthalmology department is determined based on the clinical course of the disease and standards of medical care.

Rehabilitation measures: elimination of corneal opacities, consequences of inflammatory complications, prevention of visual function decline, cosmetic rehabilitation.

7. Additional Information

No additional information available.

Criteria for Evaluating the Quality of Medical Care

References

Appendix A1. Working Group Composition

1. Kulikov, A.N., MD, Prof., Head of the Department of Ophthalmology, S.M. Kirov Military Medical Academy of the Ministry of Defense of the Russian Federation, Chief Freelance Specialist-Ophthalmologist of St. Petersburg, Member of the Association of Ophthalmologists;

2. Ilyukhin, P.A., Cand. Med. Sci., Head of the Department of Traumatology and Reconstructive Surgery, Helmholtz National Medical Research Center of Eye Diseases, Member of the Association of Ophthalmologists;

3. Chentsova, E.V., MD, Prof., Member of the Association of Ophthalmologists;

4. Boyko, E.V., MD, Prof., Director of the St. Petersburg Branch of S.N. Fyodorov Eye Microsurgery Federal State Institution of the Russian Ministry of Health, Member of the Association of Ophthalmologists; Chairman of the St. Petersburg Branch of the OOR;

5. Kharitonova, N.N., Cand. Med. Sci., Member of the Association of Ophthalmologists;

Conflict of interest none

Appendix A2. Methodology for Developing Clinical Guidelines

Methods used for collecting/selecting evidence: search in electronic databases, library resources. Description of methods used for collecting/selecting evidence: the evidence base for the recommendations consists of publications included in the Cochrane Library, EMBASE and MEDLINE databases, as well as monographs and articles in leading specialized peer-reviewed domestic medical journals on the topic. The search depth was 10 years. Methods used for assessing the quality and strength of evidence: expert consensus, significance assessment in accordance with the rating scale.

Target audience for these clinical guidelines:

1. Ophthalmologists

2. General practitioners (family physicians);

3. Ambulance doctors

4. Nursing staff

Table 1.Levels of Evidence (LoE) grading scale for diagnostic methods (diagnostic interventions)

Table 2.Levels of Evidence (LoE) grading scale for prevention, treatment and rehabilitation methods (preventive, therapeutic, and rehabilitative interventions)

Table 3. Scale for grading grades of recommendation (GR) for prevention, diagnostic, treatment, and rehabilitation methods (preventive, diagnostic, therapeutic, and rehabilitative interventions)

Procedure for updating clinical guidelines.

The mechanism for updating clinical guidelines provides for their systematic revision — at least once every three years, as well as upon the emergence of new evidence-based medicine data regarding the diagnosis, treatment, prevention, and rehabilitation of specific diseases, or in the presence of justified additions/comments to previously approved clinical guidelines, but no more frequently than once every 6 months.

Appendix A3. Reference Materials

These clinical guidelines were developed taking into account the following regulatory legal documents:

1. Order of the Ministry of Health of the Russian Federation No. 902n dated November 12, 2012 (as amended by Orders of the Ministry of Health of the Russian Federation No. 558n dated June 9, 2020, No. 44n dated February 1, 2022) «On Approval of the Procedure for Providing Medical Care to the Adult Population for Diseases of the Eye, Its Adnexa, and Orbit».

2. Order of the Ministry of Health of the Russian Federation No. 442n dated October 25, 2012 (as amended by Orders of the Ministry of Health of the Russian Federation No. 114n dated February 21, 2020, No. 746n dated July 27, 2020) "On Approval of the Procedure for Providing Medical Care to Children with Diseases of the Eye, Its Adnexa and Orbit".

3. Order of the Ministry of Health of the Russian Federation No. 203n dated May 10, 2017, «On Approval of Criteria for Assessing the Quality of Medical Care».

4. Decree of the Government of the Russian Federation No. 2406-r dated October 12, 2019 (as amended on June 9, 2023) "On Approval of the List of Vital and Essential Medicines, as well as Lists of Medicinal Products for Medical Use and the Minimum Assortment of Medicinal Products Required for the Provision of Medical Care".

5. Order of the Ministry of Health of the Russian Federation No. 103n dated February 28, 2019, «On Approval of the Procedure and Deadlines for the Development of Clinical Guidelines, Their Revision, Template Form of Clinical Guidelines, and Requirements for Their Structure, Composition, and Scientific Validity of Information Included in Clinical Guidelines».

Appendix B. Physician Action Algorithms

Appendix C. Patient Information

Guidelines for the Prevention of Eye Trauma

- Use protective safety glasses when working with moving machinery

- Follow safety regulations

- Conduct educational work with children and adolescents

- Always wear a helmet when riding a motorcycle or bicycle

- Make sure children play in a safe area

- Ensure that children of all ages are supervised by adults

- Observe traffic rules

- Do not make sudden unpredictable movements on the road

- Do not ride a bicycle in the dark

- Use necessary protective equipment (primarily a helmet for motorcycles and bicycles, and a seatbelt in a car)

- Do not drive under the influence of alcohol and do not get into a car if you think the driver is not sober

- Use a special child safety seat when traveling with a child.

Appendix G. Assessment Scales, Questionnaires, and Other Evaluation Tools

Rating scales, questionnaires, and other assessment tools for the condition of a patient with eye burns are not used