Extent of initial corneal injury as the mechanistic basis for ocular irritation: key findings and recommendations for the development of alternative assays

Currently, there are no recognized alternative tests to eliminate the use of animals in ocular irritation testing. A major reason no replacement alternatives have been developed is that the current in vivo data set provides no perspective regarding the critical cellular and molecular changes involved in initial ocular injury, subsequent responses, and repair processes in standard in vivo tests. Without this perspective, mechanistically based replacement tests cannot be developed and validated. We have proposed that the level of ocular irritation is related to the extent of initial injury, and that regardless of the processes leading to tissue damage, the extent of initial injury is the principal factor determining the outcome of ocular irritation. This article summarizes the results from our studies of various surfactants and nonsurfactants of differing irritancy that support our hypothesis. Our findings indicate that a mechanistically based alternative to in vivo ocular irritation tests would be the microscopic or biochemical measurement of initial injury using either ex vivo or in vitro corneal equivalent systems composed of corneal epithelial, stromal keratocyte, and corneal endothelial cell layers. This work also provides a well-characterized panel of materials of varying types and irritation for use in developing and validating alternative tests.

The Ocular Trauma Score (OTS)

Only based on a standardized terminology of ocular trauma terms, and using a very large number of injuries treated by a wide variety of ophthalmologists, could a reliable method be developed so that the functional outcome of a serious eye injury can be predicted with reasonable certainty. The authors used the databases of the United States and Hungarian Eye Injury Registries and, with a grant from the National Center for Injury Prevention at the Centers for Disease Control and Prevention, designed such a system.

Birmingham Eye Trauma Terminology (BETT): terminology and classification of mechanical eye injuries

Lacking a standardized terminology of eye injury types, it is impossible to fulfill a very basic requirement in medicine: that all communications be unambiguous. Accurate interpretation of published research results, which plays an absolutely crucial role in determining how an individual patient with an eye injury is treated, becomes difficult. This article presents an internationally standardized system that finally allows accurate description of eye injuries of all types.

Concomitant ocular injuries with orbital fractures

BACKGROUND AND OBJECTIVES

The orbital floor may fracture alone, and the fracture is then defined as "pure"; when there is a rim involvement, the fracture may be defined as "impure". Controversy exists as to the pathophysiology of orbital floor fractures and the incidence of orbital rim involvement. The purpose of this retrospective review was to determine the incidence of purity in orbital floor blowout fractures and the rate of ocular injuries in pure and impure floor fractures.

METHODS AND MATERIALS

The charts of 250 patients with orbital fractures, treated at a primary trauma center between 1992 and 1996, were reviewed. All fractures had been examined by the Ophthalmology Service and confirmed by high-resolution computerized tomography scans. The average age of the patients was 45 years; more than 90% were male. Motor vehicle accidents were the most commonly documented mechanism of injury, followed by interpersonal violence and falls. Almost 50% could not be categorized for mechanism of injury.

RESULTS AND/OR CONCLUSIONS

The incidence of ocular injuries in pure fractures (n = 54; 5.6%) was higher than in impure fractures (n = 26; 2.0%) (p = 0.05). Serious visual injuries following orbital fractures occurred in 17.1% of the patients; they were more common in patients with pure fractures.

Facial trauma and ocular/orbital injury

BACKGROUND AND OBJECTIVES

Ocular injuries occur commonly in patients with facial trauma. Patients with significant eye injuries may present with grossly normal eyes and good visual acuity; however, subsequent ocular disorders may become apparent. The estimates of incidence vary considerably. Trauma is the second leading cause of blindness, and a review is, therefore, warranted.

METHODS AND MATERIALS

Several extensive studies are reviewed. Blunt and penetrating trauma are examined by their respective subdivisions. The initial assessment and ophthalmologic examination of patients with facial trauma are discussed, and the type of injury that may occur secondary to trauma is delineated. Management is reviewed and discussed, including a recently developed diagnostic scoring system. Three clinical cases illustrate the procedure.

RESULTS AND/OR CONCLUSIONS

The diagnosis of ocular injuries resulting from trauma is difficult. The recently introduced scoring system was found to improve the procedure. Based on this system, the authors have devised an algorithm to assist the clinician, with emphasis on visual acuity and the importance of visual examination.

Association between orbital fracture location and ocular injury: a retrospective study

BACKGROUND

Orbital fractures are frequently accompanied by ocular injury. Any findings that provide information for diagnosing a concurrent ocular injury should improve patient care. A greater incidence of severe ocular injury with certain fracture types was hypothesized, based on orbital wall thickness.

METHODS

A retrospective review of 87 consecutive patients (107 fractured orbits) was performed by the Ophthalmology Department of an urban Level 1 trauma center.

RESULTS AND CONCLUSIONS

Severe injuries were associated with orbital apex fractures (p = 0.00001), with lateral wall fractures (p < 0.04), and with Le Fort Type III fractures (p < 0.02). Moderate injuries were associated with isolated orbital floor fractures (p < 0.01). Apex, lateral wall, and Le Fort Type III fractures have a greater association with severe ocular injuries than other fracture types.

[Incidence of ocular trauma in Clinical Hospital Oradea between 1997-1999]

The purpose of the study is to analyse the great number of ocular injuries which were diagnosed and treated in the out-patients clinic or in the hospital in 1997-1999. Ocular trauma seems to be related to the working place or the main activities of the patients, such as agriculture or housekeeping. Ocular injuries in children are significant as number and prognosis. Blunt trauma, ocular perforations, ocular foreign bodies and burns were studied separately for children, housekeepers, unemployed, working and retired people. Due to their number and complexity, ocular trauma represent a very important part in the activity of an ophthalmology department. The conclusion of the study is the number of ocular injuries decreased over the years because of the reduced industrial activity in our town. Similar ocular injuries in retired and working people suggest that retired people are still active. The prognosis of ocular trauma is better if the patients come early to be seen by the specialist, if the treatment is adequate and if the department has a proper equipment for advanced surgery techniques.

Ocular emergencies in Kinshasa (Democratic Republic of Congo)

PURPOSE

To determine frequencies of ocular emergencies and identify their nature.

DESIGN

Observational case series.

METHODS

In a retrospective study, the records of all 118 consecutive patients seen in emergency room during an eleven-month period were reviewed.

RESULTS

Ocular emergencies represented 4% of the 2917 new patients visiting the department of Ophthalmology during this time. There was a 2.1/1 male to female preponderance and a peak age of presentation between 11 and 30 years. The mean age was 26 years +/- 17. Ocular trauma (68 patients) accounted for over two-fourths (57.6%) of the total cases. Only 16% of patients presented within 48 hours. Fifty-one percent of injuries occurred to the left eye, 38% to the right, and 10% bilaterally. The commonest ocular injury problems were eyelid laceration (13 patients, 19.1%), post-traumatic iritis (12 patients, 17.6%), and corneal laceration and penetration (10 patients, 14.7%), accounting for 51% (35 patients) of the total. Home- and work-related ocular injuries accounted for 54% of all ocular injuries. Thirty-three percent of all ocular injuries were caused by assault and fight, and 15% were related to motor vehicle accident. For the non-traumatic ocular emergencies, the main aetiological factor was inflammation (18%).

CONCLUSION

Our study showed that males account for the majority of eye injuries and this class is more prone to assault-related injuries. In our country prevention strategies must take account of these.

Mechanical eye (globe) injuries in children

PURPOSE

The epidemiology of mechanical eye injuries in children was studied to identify the agents of injury and their contribution to the severity of visual loss and to suggest preventive measures.

METHODS

The mode, type, and severity of injury were correlated with the visual acuity 6 months after the injury in all children with mechanical eye injuries between January 1994 to January 1999.

RESULTS

Of the 68 children with mechanical eye injuries, the mode of injury was host (child) related in 12 (17.65%) patients, agent related in 40 (58.82%) patients, and environment related in 16 (23.53%) patients. Mild injuries were seen in 22 (32.35%) patients, 31 (45.59%) patients had moderate injuries, and 15 (22.06%) patients had severe injuries. None of the patients with host-related injuries had a severe injury. Six (66.67%) patients with host-related injuries had a good visual outcome and none had a poor outcome. Among patients with agent-related injuries, 11 (25%) had a good outcome, 14 (40%) patients had a fair outcome, and 10 (22.5%) patients had a poor outcome. Of the patients with environment-related injuries 3 (33.33%) each had good, fair, and poor visual outcomes.

CONCLUSIONS

Agent and environment-related injuries had a far worse outcome than host-related injuries. This epidemiological classification directly suggests practical preventive measures that can be adopted at home or at school to reduce the incidence and severity of ocular injuries. The other predictors of the final visual outcome were the severity of the injury at presentation and the necessity for a secondary surgical procedure.

Ocular firework injuries at New Year's eve

PURPOSE

To prospectively study mechanisms and injury characteristics of ocular firework burns.

METHODS

A prospective analysis of all patients with firework injuries attending the Department of Ophthalmology, University of Vienna, between 1994 and 2001. We looked for classes of fireworks and mechanisms of injuries. The number of diagnoses was established and their severity classified.

RESULTS

During this period (8 years) we identified 116 eyes of 102 patients. 67/102 (66%) of all injuries were caused by class II and III fireworks. Patients ranged between 4 and 83 years. Ocular injuries occurred more frequently in males (69, 68%) and affected the right eye in 53 patients (52.5%). Ocular firework injuries to minors (under the age of 18 years) occurred in 48 (49%). The most common types of injury were skin and corneal erosions and abrasions (32/116, 28%). 11/116 eyes (10%) had severe injuries. 8 of 11 severe injuries (72%) occurred in minors (<18 years). 2 patients (1.7%) developed permanent blindness. In 32/116 patients (28%), the ocular trauma resulted in visual impairment, mainly due to corneal scars or retinal pathologies. In all patients, the severity index was 1.4 +/- 0.8. In minors the severity index was 1.6 +/- 1.0, in adults 1.2 +/- 0.5 (p = 0.013).

CONCLUSION

Injuries in minors were significantly more severe than those in adults. Possible preventive measures include legislation, education of minors and eye protection.

The management of corneal trauma: advances in the past twenty-five years

Over the past quarter century, advances in our understanding of corneal anatomy, physiology, and wound healing have all played an integral role in the management of corneal trauma. As the etiologies of corneal trauma have changed, so has our understanding of the impact of injury on corneal function as it relates to visual rehabilitation. Numerous new classes of antibiotics, antiinflammatory agents, and tissue adhesives have emerged. Occlusive therapy has advanced from simple pressure patching bandage soft contact lenses and collagen shields. Surgical instrumentation, operating microscopes, viscoelastic substances, and suture materials have all improved the outcomes of corneal trauma repair. Improved understanding of the refractive properties of the cornea through topography and alternative suture techniques has helped us restore the natural corneal curvature and visual outcomes. Consequently, in the last quarter of this century our therapeutic approaches to cornea trauma, both medical and surgical, have improved.

Epidemiology of ocular trauma in Australia

PURPOSE

To describe the prevalence and risk factors of ocular trauma in a representative sample of Australians aged 40 and over who reside in the state of Victoria.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Australians aged 40 years and older living in Victoria.

METHODS

Cluster, stratified sampling was used to identify permanent residents for a population-based study of eye disease. A standardized examination that included visual acuity and information about ocular trauma was conducted.

MAIN OUTCOME MEASURES

Self-reported history of ocular trauma and circumstances surrounding the events.

RESULTS

A total of 3271 (83% of eligible) Melbourne residents and 1473 (92% of eligible) rural residents were examined. The overall rate of eye injury history in Victoria was 21.1% (95% confidence limits [CL] 19.6%, 22.5%). Men were far more likely than women to have ever experienced an eye injury (34.2% versus 9.9%), and rural men were more likely than Melbourne men to have ever had an eye injury (42.1 % versus 30.5%). The workplace accounted for the majority of eye injuries (60%), followed by the home (24%). The location with the highest percent of people reporting the use of eye protection at the time of the injury was the workplace (18.5%); the workplace accounted for the lowest rate of hospitalization (4.9%). The industry with highest cumulative rate of eye injuries was communication (14 per 1000), whereas the highest occupation-specific cumulative rates of eye injury were recorded for tradespersons (18 per 1000).

CONCLUSIONS

Although ocular trauma is usually not associated with bilateral vision impairment, it is a major public health problem in Australia. Rural men, people engaged in hammering or sport, and those in the trades are at highest risk and require specific, targeted, prevention messages.

Evaluation and classification of pediatric ocular trauma

PURPOSE

To offer to the pediatric emergency physician consistent and unambiguous terms for the description of pediatric ocular trauma, based upon an adapted version of a standardized classification system. To show the potential effect of this reclassification system in a tertiary care emergency department.

METHODS

The authors reviewed a new classification system of ocular trauma and adapted it for use by pediatric emergency physicians. In addition, a retrospective analysis of the records of pediatric patients presenting over a 2-year period to a tertiary emergency department with ocular complaints was performed. The diagnoses related to ocular trauma were reclassified according to the new classification system.

RESULTS

Over a 2-year period, 117 pediatric patients were evaluated for ophthalmic complaints. Sixty-seven (57%) of these cases involved an ocular contusion or ruptured globe; however, six disparate diagnoses were given. The cases were reclassified into an adapted, unambiguous, classification system. In some cases, the reclassification altered the indication for immediate ophthalmologic referral.

CONCLUSION

There is currently no standardized system of terminology to describe pediatric ocular trauma. This may lead to confusion in communication among the pediatric emergency physician, the pediatrician, and the ophthalmologist. Consistent, unambiguous, terminology will assist in this communication, facilitate the writing of peer-reviewed articles and case reports, and increase the level of accurate documentation in the medical record.

[New priority trends in ocular traumatism]

Types of ophthalmic traumas subject to change at present are enumerated: communal, criminal, war traumas, and injuries resultant from emergency situations (disasters). The changes are discussed. Main factors which should be borne in mind when investigating the problem of ocular injuries are determined. Priority trends of research in ophthalmic traumatology are defined.

Eye injuries in patients with major trauma

BACKGROUND

A study was performed to determine the type and frequency of ocular injuries in patients with major trauma.

METHODS

All patients with ocular and adnexal injuries (n = 178) among 1,119 patients admitted with major trauma (Injury Severity Score >15) to the Royal Prince Alfred Hospital from July 1990 to December 1997 were analyzed.

RESULTS

Sixteen percent of the major trauma cohort had ocular or orbital trauma. Fifty-five percent of patients with injuries involving the face had ocular or orbital injuries. A range of ocular injuries was seen. Analysis of the major trauma cohort showed that motor vehicle drivers, orbital and base of skull fractures, eyelid lacerations, and superficial eye injuries were strongly associated with vision-threatening injury.

CONCLUSION

Patients with major trauma and facial injuries have a high risk of vision-threatening injury. Patients with orbital fractures, base of skull fracture, eyelid lacerations, and superficial eye injuries should be assessed by an ophthalmologist as part of the early management of their trauma to determine whether an ocular injury is present.

Orbital trauma

In this review, a number of current issues on the management of orbital trauma are discussed including the indications for orbital exploration in zygomatic complex fractures, the utility of transantral endoscopy in orbital trauma surgery, and preferred implant materials in orbital reconstruction. We emphasize the need for a classification system to define some of the clinical terms used in describing orbital trauma, to improve communication between clinical services, and to standardize the clinical literature on orbital trauma.

A review of ocular emergencies in a Taiwanese medical center

BACKGROUND

Ocular injury is one of the most common problems in the Emergency Department (ED), but a general survey of ocular injuries has rarely been reported in the literature. This article reviews cases of ocular injury collected in the ED of a medical center over a 12-month period.

METHODS

A retrospective analysis was done on 1,314 consecutive patients who presented with eye complaints to the ED of the Veterans General Hospital-Taipei between November 1993 and October 1994. Common ocular diagnoses and their associated variables were assessed separately.

RESULTS

Ocular injuries occurred in a male to female ratio of about 1.9:1 with a peak age in the third decade. Diagnoses were grouped as trauma (43.8%) and non-trauma (56.2%). Corneal abrasion was the most common trauma reported. The main circumstances of eye trauma were play (50.0%) in children (< 15 years), work (37.1%) in the age group of 16 to 59 years and domestic activity (45.8%) in patients over 60 years of age. Blunt objects and contusions (hits or falls) caused nearly 50% of all ocular injury cases. Most of the non-traumatic cases were due to acute conjunctivitis (19.1%), followed by contact lens (CL)-related disorders (11.4%). Three cases of CL-induced corneal ulcer resulted in permanent visual morbidity. There was a trend toward an increase in acute conjunctivitis in the summer, corneal ulcer in the spring and acute glaucoma in the winter.

CONCLUSIONS

Young males were found to run a higher risk of ocular accidents, especially at work. Penetrating injuries with or without a retained intraocular foreign body were the leading cause of poor visual outcomes and often occurred in patients without protective eyeglasses. With the widespread use of CLs, many potentially serious complications were noted in the ED, which deserve attention.

Grading scales for contact lens complications

Grading scales have been developed to assist practitioners in recording the level of severity of ocular complications of contact lens wear. Eight common complications are depicted in five levels of severity--from grade 0 (normal) to grade 4 (severe). The intersubject variance in grading was determined to be 1.0 scale units, which by coincidence concurs exactly with the key design strategy of the grading scales that each grading step of 1.0 corresponds to a clinically significant difference in severity.

[Penetrating ocular injuries: an epidemiologic and retrospective study]

Penetrating injuries of the eye are an important cause of unilateral visual loss. We studied a series of 82 cases of penetrating injuries treated here from 1987 through 1993. The injuries were caused by sharp objects in 66% and blunt trauma in 6%. The prognosis after a penetrating injury is greatly influenced by the nature of the injury and the extent of the initial drainage. Among factors associated with an unfavorable visual outcome were diminished preoperative visual acuity and scleral wounds with dense vitreous hemorrhage.

[Occupational accidents and eye injuries treated at the Rambam Medical Center]

To determine the prevalence of occupation-related eye injuries, we analyzed the records of 24,632 patients treated at our emergency surgical department over a 3-year period. Occupational accidents accounted for 17.6% of such cases. A third of them (1374 patients) were referred to the ophthalmic emergency room for further examination. In 89% (1223) of these, at least 1 pathological ocular finding was detected, and 8.3% (114) of them were hospitalized. Penetrating eye injuries were found in 5.2% (72). The commonest eye injury was corneal foreign body found in 42.8%.

A system for classifying mechanical injuries of the eye (globe). The Ocular Trauma Classification Group

PURPOSE

To develop a classification system for mechanical injuries of the eye.

METHODS

The Ocular Trauma Classification Group, a committee of 13 ophthalmologists from seven separate institutions, was organized to discuss the standardization of ocular trauma classification. To develop the classification system, the group reviewed trauma classification systems in ophthalmology and general medicine and, in detail, reports on the characteristics and outcomes of eye trauma, then established a classification system based on standard terminology and features of eye injuries at initial examination that have demonstrated prognostic significance.

RESULTS

This system classifies both open-globe and closed-globe injuries according to four separate variables: type of injury, based on the mechanism of injury; grade of injury, defined by visual acuity in the injured eye at initial examination; pupil, defined as the presence or absence of a relative afferent pupillary defect in the injured eye; and zone of injury, based on the anteroposterior extent of the injury. This system is designed to be used by ophthalmologists and nonophthalmologists who care for patients or conduct research on ocular injuries. An ocular injury is classified during the initial examination or at the time of the primary surgical intervention and does not require extraordinary testing.

CONCLUSIONS

This classification system will categorize ocular injuries at the time of initial examination. It is designed to promote the use of standard terminology and assessment, with applications to clinical management and research stud ies regarding eye injuries.