|Year : 2015 | Volume
| Issue : 3 | Page : 377-382
Past history of ocular trauma in an Iranian population-based study: Prevalence and its associated factors
Hassan Hashemi1, Mehdi Khabazkhoob1, Mohammad Hassan Emamian2, Mohammad Shariati3, Saman Mohazzab-Torabi1, Akbar Fotouhi4
1 Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
2 Department of Epidemiology, School of Public Health, Shahroud University of Medical Sciences, Shahroud, Iran
3 Department of Community Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
4 Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
|Date of Web Publication||1-Jul-2015|
Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Purpose: The purpose of this study was to determine the prevalence of a history of ocular trauma and its association to age, sex, and biometric components.
Materials and Methods: Residents of Shahroud, Iran aged 40-64 years, were sampled through a cross-sectional study using multistage cluster sampling. Three hundred clusters were randomly selected, and 20 individuals were systematically selected from each cluster. The subjects underwent optometric and ophthalmic examinations, and ocular imaging. A history of ocular trauma was determined through personal interviews.
Results: The prevalence of a history of trauma and blunt trauma, sharp trauma, and chemical burns were 8.57%, 3.91%, 3.82%, and 1.93%, respectively. After adjusting for age, the rate of all types of trauma was significantly higher for males. Only the prevalence of chemical burns significantly decreased with aging. A history of hospitalization was stated by 1.64% of the subjects. The axial length was significantly longer in cases with a history of trauma. The corneal curvature was significantly larger in cases with a history of sharp trauma and chemical burns. The prevalence of corneal opacities was significantly higher among cases with a history of the blunt trauma odds ratio (OR = 2.33) and sharp trauma (OR = 4.46). Based on corrected visual acuity, the odds of blindness was 3.32 times higher in those with a history of ocular trauma (P < 0.001).
Conclusion: A considerable proportion of the 40-64-year-old population reported a history of ocular trauma. This observation has important health implications. Blindness, corneal opacities, and posterior subcapsular cataract were observed more frequently among these cases, and they demonstrated differences in some ocular biometric components.
Keywords: Cross-sectional Study, Middle-East, Ocular Trauma
|How to cite this article:|
Hashemi H, Khabazkhoob M, Emamian MH, Shariati M, Mohazzab-Torabi S, Fotouhi A. Past history of ocular trauma in an Iranian population-based study: Prevalence and its associated factors. Middle East Afr J Ophthalmol 2015;22:377-82
|How to cite this URL:|
Hashemi H, Khabazkhoob M, Emamian MH, Shariati M, Mohazzab-Torabi S, Fotouhi A. Past history of ocular trauma in an Iranian population-based study: Prevalence and its associated factors. Middle East Afr J Ophthalmol [serial online] 2015 [cited 2019 Jun 24];22:377-82. Available from: http://www.meajo.org/text.asp?2015/22/3/377/159766
| Introduction|| |
Ocular trauma is an important cause of blindness in children and the middle-aged. Ocular trauma is responsible for 7-45% of noncongenital monocular blindness in adults, especially in developing countries. , Previous reports indicate that 90% of cases are preventable using simple measures. Cases of ocular trauma lead to permanent damage that can impact occupation and quality of life, cause psychological disorders, and increase the burden of disease. In America, the annual treatment cost for different types of ocular trauma is approximately 934 million dollars. ,,, Various studies have examined the rate of traumatic ocular damage in developed and developing countries. , All these studies indicate a high-risk of trauma among children and adolescents (under 30 years of age), stating that 12-38% of children reported a history of ocular trauma. , The annual rate of blindness due to ocular trauma is 1.6 million, 2.3 million cases cause bilateral disability, and 19 million cause unilateral visual impairment.  In America, 2 million cases of ocular trauma are registered annually; of these, 40,000 lead to permanent blindness and 30% of the case occur in children under 17 years of age. , The majority of trauma-related injuries require emergency surgery and potentially, hospitalization with 4.9-89/100,000 hospitalizations due to ocular trauma.
Several epidemiologic studies have reported the prevalence of a history of trauma. Due to the potential for visual morbidity and public health burden of ocular trauma, knowledge of the prevalence of ocular trauma in different populations is required. It is also necessary to identify the common types and patterns of ocular trauma as they may vary from region to region. Different types of ocular trauma may cause a different kind of injury to the eyes. Common ocular complications include traumatic cataract, changes in refraction following sharp trauma to the corneal surface, and even more serious retinal problems following severe trauma. Data on the distribution and patterns of ocular trauma can help health care experts set appropriate priorities for ocular trauma within the public health sector. The information can also be used to develop protocols to prevent ocular trauma, especially in children. To the best of our knowledge, the only population-based epidemiologic data on ocular trauma in Iran comes from the Tehran Eye Study. Ocular trauma results in detrimental effects on the physical and mental health of society, and a significant financial burden on the health system. Hence, data on the prevalence and patterns of ocular trauma in other Iranian populations is required. The present report evaluates the prevalence of ocular trauma, the risk factors, and their association to blindness.
| Materials and Methods|| |
This report is part of the Shahroud Eye Cohort Study; the first cross-sectional phase was conduction in 2009. The detailed methodology of the study had been published elsewhere.  To summarize briefly; the target population of the study was 40-64-year-old residents of Shahroud, a City in Northern Iran. Potential participants were selected through multistage cluster sampling from 9 Health Care Centers in Shahroud. Three hundred clusters were randomly selected, and from each cluster, 20 individuals were systematically selected. To enroll these participants, we first started with the head household that was chosen at random and then proceeded in a clockwise direction with adjacent households using a systematic approach. If there was no response on the first contact, the household was approached again in the evening or another day so that they could be invited to participate in the study. All potential subjects were invited to the study site which was equipped with ophthalmic, optometric, and imaging facilities. After obtaining consents, the subjects underwent an interview to gather demographic information such as age, gender, and education and they were asked about their history of smoking and certain eye conditions. To collect detailed information about a history of ocular trauma, we recorded the type of trauma (blunt, sharp, chemical burn), and any history of hospitalization, surgery or medical visits due to the trauma.
All participants underwent measurement of uncorrected near and distance visual acuity using the logarithm of the minimum angle of resolution chart. Each eye underwent an autorefraction (AR 8800 Autorefractometer; Topcon Corp., Tokyo, Japan), and results were used for objective refraction (Heine retinoscope; Heine Optotechnik, Herrsching, Germany) and subjective refraction. For ophthalmic exams, participants underwent slit lamp biomicroscopy. Cataract and lens opacities were determined based on the Lens Opacities Classification System III (LOCS III). Similar to other studies, nuclear cataract was defined as nuclear color or nuclear opacity grade 4 or worse. In cases of cortical and posterior sub capsular opacities, an LOCS III grade 2 or worse was defined as cataract.
Biometric tests were done after measuring the visual acuity and before cycloplegic refraction or ophthalmic exams. All participants were tested using the Allegro Biograph (WaveLight AG, Erlangen, Germany).
In this study, we describe the prevalence of a history of different types of trauma and the 95% confidence intervals (CI). To explore associations of the history with other variables, we used simple and multiple logistic regression models and calculated the odds ratio (OR). Comparison of mean ocular biometric components in people with and without a history of ocular trauma was performed with linear regression tests. The effect of cluster sampling was accounted for in calculating the standard error and CI. A P < 0.05 was considered statistically significant.
| Results|| |
Of the 6311 invitees, 5190 (82.2%) participated in the study. The mean age of the respondents was 50.9 ± 6.25 years (range, 40-64 years), and 58.6% were female. The overall prevalence of a history of trauma was 8.57% (95% CI: 7.72-9.43). The prevalence of a history of a blunt trauma, sharp trauma, and chemical burn was 3.91% (95% CI: 3.3-4.52), 3.82% (95% CI: 3.2-4.43), and 1.93% (95% CI: 1.51-2.34), respectively.
[Table 1] summarizes the prevalence of the different types of trauma based on age and patient demographics. [Table 2] presents the association of type of trauma with age and gender, according to multiple logistic regression. After adjusting for age, the prevalence rates of the different types of trauma were significantly higher among males. Only chemical burns significantly correlated to age, with prevalence significantly decreasing with age.
|Table 1: Prevalence of history of ocular trauma, by type, gender, and age in Shahroud, Iran|
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|Table 2: The association of type of ocular trauma with age and gender in Shahroud, Iran|
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The rates medical of visits due to trauma was 5.43% (95% CI: 4.47-6.12). The rates of hospitalization and surgery due to ocular trauma were 1.64% (95% CI: 1.24-2.03) and 0.67% (95% CI: 0.37-0.97), respectively. Of those with a history of blunt trauma, 46.3% stated they saw a physician; for those with sharp trauma and chemical burns, 79.4% and 70.5%, respectively presented to a physician. The highest hospitalization rate was seen among cases with a history of chemical burns (30.7%), and 11.4% and 18.9% of those with blunt trauma and sharp trauma, respectively, required hospitalization.
[Table 3] describes the biometric components in cases with and without a history of ocular trauma. In cases with a history of trauma, axial length was significantly higher. Furthermore, the corneal radius of curvature was significantly larger in those with a history of sharp trauma and chemical burns.
|Table 3: Mean and 95% CI of ocular biometric components in participants with and without a history of ocular trauma|
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The prevalence of posterior subcapsular cataract (PSC) was significantly higher in those with a history of blunt trauma (P = 0.011). The prevalence of PSC was 3.5% for cases with a history of trauma and 1.6% in those without a history of trauma. There was no significant difference nuclear cataract, cortical cataract, and other types of trauma (P > 0.05, call cases). The prevalence of corneal opacity was significantly higher in participants with a history of blunt trauma (OR = 2.33; 95% CI: 1.61-3.37). The prevalence of corneal opacity was significantly higher in those with a history of sharp trauma (OR = 4.46; 95% CI: 2.99-6.64). However, there was no significant association between corneal opacity and chemical burns (P = 0.218). Furthermore, both corrected and uncorrected visual acuity were significantly worse in participants with a history of blunt or sharp trauma to the eye (P < 0.001).
Based on uncorrected and corrected visual acuity worse than 20/400, the prevalence of blindness in at least one eye in cases with a history of ocular trauma was 11.62 (95% CI: 8.6-14.6) and 7.3% (95% CI: 4.8-9.8), respectively. For those without a history of ocular trauma, these rates were 3.3% (95% CI: 2.8-3.8) and 1.4% (95% CI: 1.1-1.8), respectively. After adjusting for age and gender, the odds of blindness were significantly higher for those with a history of ocular trauma based on uncorrected vision (OR = 3.2; 95% CI: 2.06-4.41) and corrected vision (OR: 3.33; 95% CI: 2.00-5.52) (P < 0.001).
| Discussion|| |
In this report, we described the history of ocular trauma in a 40-64-year-old population of Shahroud City. This is the second population-based study evaluating the history of trauma in an Iranian population. In addition, to describing the prevalence of a history of trauma by type of trauma, we examined the biometric components in individuals with a history of trauma to provide new information.
Overall, 8.57% of the study participants stated a history of ocular trauma. A review of the relevant literature shows that rates vary widely and can be between 1.7% and 21.1%. The prevalence rates of ocular trauma worldwide vary considerably. For example, the prevalence is 1.7% in Beijing,  3.97% in Southern India,  4.5% in the rural population of Southern India,  5% in the Singapore Malay,  6.98% in the US,  19.8% in the Beaver Dam Study,  and 21.1% in Australia.  Notably, the prevalence of ocular trauma appears to be higher in industrialized countries such as the US and Australia. This could be interpreted as a higher exposure to dangerous factors or it could be due to the better registration of incidents and trauma in these countries. The prevalence of a history of ocular trauma is relatively high. Since trauma is the most important cause of monocular blindness, they deserve better attention so that they can be prevented through interventional and educational programs in the health system, especially for elderly and the visually impaired.
As demonstrated, the prevalence of a history of ocular trauma decreased with age. Studies of ocular trauma an age have been inconclusive. Some studies report increased ocular trauma with age,  while others report the opposite. , Most studies on younger populations , report that ocular trauma increases with age. A variety of explanations has been presented to justify correlations between a history of ocular trauma and age. We cannot explain how age might function as a risk factor for ocular trauma.
The age-related increase in the prevalence of a history of ocular trauma seen in some studies can be attributed to the cumulative effect seen at an older age. Or it could be that a higher rate of visual impairment at older age increases the chance of incidents and trauma to be reported. However, in agreement with our results, there are studies that have observed a decreased prevalence of a history of ocular trauma with aging. Two factors may be contributing to this effect. First, aging is associated with a higher rate of forgetfulness and mental disease which increases recall bias. Second, it could be an age cohort effect; they might have been exposed to fewer and lower environmental and occupational risk factors when they were younger and working, and the lower prevalence is, in fact, work-related. In agreement with previous studies, the prevalence of ocular trauma was higher in males; this is quite expected because of the occupational conditions for males and their exposure to risk factors outside the home environment.
According to our findings, 5.43% of the study participants sought medical treatment and 1.64% stated a history of hospitalization as a result of their ocular trauma. In addition, 0.67% of the participants required surgery. This points to the significance of the burden of ocular trauma on the health system and is stated in other reports from India, America, and Australia. ,,,, As an ophthalmic emergency, ocular trauma tends to require hospitalization and urgent care. The incidence of hospitalization as a result of ocular trauma is 8/100,000 population in Scotland, 12.6 in Singapore, and 13.2/100,000 in America. ,,,, Rates from developing countries are much higher due to limited resources for prevention. For example, 33/100,000 people are hospitalized in Guinea-Bissau.  Of note, not only does ocular trauma cause complications and consequences for individuals, it is responsible for great treatment expenses that are imposed on the health system.
Our study is one of the few that concerns not only visual acuity and some ocular disorders in cases with a history of ocular trauma, but also examines associations with ocular biometric components. As demonstrated, mean axial length was significantly higher in the group with a history of ocular trauma. This association is rarely mentioned previously; ocular trauma is unlikely to change the axial length, but since myopia is more common among people with longer axial length, the visual impairment associated with myopia, especially high myopia, may increase the chances of ocular trauma. Though some studies have shown that ocular trauma can cause myopia by inducing changes to the anterior chamber and the location and thickness of the lens.  In our study, the corneal radius of curvature was higher in cases with a history of sharp trauma and chemical burns. Corneal changes induced by corneal tear and necrosis after chemical burns flatten the cornea. Thus, the cornea in such cases is not a virgin cornea and intraocular lens power calculations must address this issue.
We found a higher prevalence of PSC in cases with a history of ocular trauma, while other types of cataract showed no statistically significant association. This association has been studied previously by several investigators. In Australia, McCarty et al.  reported no significant correlation between a history of trauma and any type of cataract. However, an exclusive report on ocular trauma and different types of cataract by Wong et al.  from the Beaver Dam Eye Study discussed an association similar to our findings; that is, they found that a history of trauma is associated with a higher rate of PSC and other types of cataract have no significant correlation after correcting for confounding factors. Further, study of these associations is warranted to understand the biology. We believe trauma-related changes in the vitreous may induce more oxidation, and spread of oxygen from the retina to the posterior lens can lead to PSC cataract. Lens opacification as a result of oxidative changes and vitreous thinning has been discussed by Boscia et al. 
Our findings indicated an association between corneal opacity and blunt and sharp trauma. This confirms the findings of Brian et al.  and Liu et al.  According to Chang et al.  trauma is the leading cause of corneal opacities in children. Currently, 50% of corneal opacities in children are due to trauma. From a health perspective, these observations indicate the need to aware of corneal opacity as a complication of ocular trauma because many studies have shown that corneal opacities are among global causes of blindness and visual impairment. Thus, practitioners must examine the eyes for possible corneal changes as a result of trauma, which may lead to blindness. We have shown that these cases are 3.5 times more likely to be blind.
There are some advantages and some limitations to our study design. An advantage is the large sample size selected from the general population, and evaluation of associations of a history of ocular trauma with biometric components, some ocular disorders, visual status, and the proportion of people requiring hospitalization due to ocular trauma. However, the data were collected through interviews, and the exact date of trauma was not clear. Hence, our results might underestimate the prevalence due to recall bias; therefore, our results should be interpreted with caution.
Financial support and sponsorship
Noor Ophthalmology Research Center and Shahroud University of Medical Sciences.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]