Comparison of Visual Symptom Frequency and Occupational Issues Between Patients With and Without Concussion

Abstract

Importance: Occupational therapy practitioners’ knowledge of and advocacy for clients with visual symptoms postconcussion can have a considerable impact on recovery.

Objective: To compare the frequency of vision symptoms and occupational performance deficits in a sample of participants with and without concussion.

Design: Cross-sectional study.

Setting: Sports medicine clinic.

Participants: Adolescents and adults with concussion (n = 20) and musculoskeletal injuries (n = 19).

Outcomes and Measures: Measures included monocular amplitude of accommodation, near point of convergence, Binocular Vision Assessment (BVA) computerized screening for phoria, BVA computerized screening for fusional vergence, the Developmental Eye Movement Test, the Canadian Occupational Performance Measure, and the Convergence Insufficiency Symptom Survey–Concussion Version (CISS–CON).

Results: We found significant differences between participants with and without concussion using the CISS–CON (p = .001), positive fusional vergence (p = .02), and near point of convergence (p = .02). Participants with concussion scoring above cutoffs on multiple measures reported poorer performance (p = .005) and satisfaction (p = .004) with valued occupations.

Conclusions and Relevance: Concussion has a detrimental effect on vision and occupation, and occupational therapy practitioners are well-positioned to assess and address issues arising from this relationship.

Plain-Language Summary: Vision symptoms commonly experienced after a concussion are associated with reduced occupational performance and satisfaction and can have a considerable impact on recovery. Occupational therapy assessment for clients with concussion should include screening for vision difficulties.

This study compares the frequency of vision symptoms and occupational performance deficits in a sample of participants with and without concussion.

Occupational therapy practitioners have an active role in the assessment and treatment of visual efficiency and visual information processing, especially when working with people with acquired brain injury. Within recent decades, awareness of mild traumatic brain injury in sports has increased (Cusimano et al., 2017). This knowledge has coincided with a rise in the number of clients seeking treatment of milder injuries (Seeley et al., 2014). Medicine and optometry literature highlight the frequency of visual dysfunction among patients with traumatic brain injuries from sport-related concussions (Master et al., 2016; Scheiman et al., 2021). Visual disturbances are a hallmark symptom of concussion and can have a considerable impact on people’s occupations. This finding points to the need for increased collaboration among the fields of medicine, occupational therapy, and optometry in identifying and remediating these issues.

Client care postconcussion frequently requires the expertise of a multidisciplinary team (Roberts et al., 2016). As experts in enabling occupation, occupational therapy practitioners screen clients for visual dysfunction and advocate for a more specialized evaluation and assessment from a vision professional, such as an optometrist (Radomski et al., 2014) or an ophthalmologist. In collaboration with vision specialists, occupational therapy practitioners can compare the client’s visual functioning with the requirements of the client’s valued activities and design treatment plans to improve functional performance levels. The purpose of this study was to compare the frequency of visual signs and symptoms and occupational performance deficits between patients presenting with and without concussion to a sports medicine clinic in a midsized Canadian city.

Method

Design

A cross-sectional design was used in this study. The independent variable was injury type (concussion vs. musculoskeletal). Primary dependent variables were signs and symptoms of visual disturbance, as determined by a series of screening measures detailed in the procedure. Two theoretical models were used in this research: Warren’s (1993) hierarchical model for evaluation and treatment of visual perceptual dysfunction and Scheiman’s (2011) three component model of vision. These models served as a basis for examining the relationship between vision symptoms and occupational performance in a group of sports medicine patients with and without concussion. Ethics approval was granted by the research ethics boards of the host institution and the authors’ affiliated university; written informed consent was received from all eligible participants and minor participants’ guardians.

Participants

The 39 enrolled participants were recruited in March and April 2019 from an outpatient clinic that included a specialized concussion and sports medicine clinic and physiotherapy services. Participants were age 13 yr or older with a medical diagnosis of concussion or musculoskeletal injury in the past 24 mo. Exclusion criteria for both groups included known history of strabismus, amblyopia, strabismus surgery, patching, or vision therapy as well as the inability to participate in vision testing, including corrected visual acuity of worse than 20/30 in either eye.

Procedure

An occupational therapist with postgraduate training in vision assessment and remediation administered a screening battery for visual signs and symptoms using assessments of the most common postconcussion vision symptoms according to the literature (Radomski et al., 2014) and an occupational performance assessment. The Chronister Pocket Acuity Chart was used to measure visual acuity to ensure that participants had at least 20/30 vision. Monocular amplitude of accommodation and near point of convergence were measured with a Bernell Accommodation Rule. Phoria and fusional vergence were measured with a Binocular Vision Assessment (BVA) computerized screening tool. Saccades were measured with the Developmental Eye Movement Test (Richman, 2016). Participant ratings of the effects of injury on their daily occupations were measured with the Canadian Occupational Performance Measure (COPM; Law et al., 2005), and subjective visual complaints were measured with the Convergence Insufficiency Symptom Survey–Concussion Version (CISS–CON; M. Scheiman, personal communication, February 2019). Descriptions of these assessment tools can be found in Supplemental Table A.1 (available online with this article at https://research.aota.org/ajot).

We analyzed data for the outcome measures using differential statistics. Chi-square analyses determined whether participants with concussion had differences in frequencies of vision symptoms than participants without concussion. We determined group differences in scale scores for outcome measures of interest using independent samples t tests (for parametric data) and Mann–Whitney U tests (for nonparametric data). Chi-square analyses were used to determine group differences in COPM categories identified as problematic by participants. Significance level for all tests was set at p = .05. We analyzed all data using IBM SPSS Statistics (Version 24).

Results

Of the 39 enrolled participants, 20 had a diagnosed concussion, and 19 had a diagnosed musculoskeletal injury without concussion. The mean age was 33.5 yr (age range = 13–66 yr), with no significant difference between the mean ages of the two groups (p = .57). Of the study participants, 71% identified as female. Age and cause of injury information by condition group can be found in Table 1.

Table 1.

Average Age and Cause of Injury by Condition Group

Group Type	Average Age, yr	Cause of Injury				Total
Group Type	Average Age, yr	Sports	MVC	Work	Other	Total
Concussion	32.05	8	4	1	7	20
Musculoskeletal	35.11	13	0	1	5	19
Total	33.54	21	4	2	12	39

Note. MVC = motor vehicle collision.

Vision Screening Results

Overall, a statistically significant difference was found between groups in frequency of failure for the CISS–CON (p = .001), positive fusional vergence (p = .02), and near point of convergence (p = .02). Of the participants with concussion, 80% failed two or more screening tests compared with 42% of participants with musculoskeletal injuries (p = .02). A between-groups comparison revealed that participants with concussion also showed a general trend of failing at least one screening test more often than participants with musculoskeletal conditions, with 95% of clients with concussion failing at least one screen compared with 70% of patients with musculoskeletal injuries (p = .07). Comparison of positive screen rates can be found in Table 2.

Table 2.

Comparison of Screen Failure Rate Between Concussion and Musculoskeletal Groups

Group Type or Statistical Test	n (%)
Group Type or Statistical Test	Near Point of Convergence >10 cm	CISS–CON Score >21	Positive Fusional Vergence Fail a	Single Positive Screen	>1 Positive Screen
Concussion (n = 20)	13 (65)	16 (80)	18 (90)	19 (95)	16 (80)
Musculoskeletal (n = 19)	5 (26)	5 (26)	10 (52)	14 (74)	8 (42)
χ²(1)	5.87	11.30	6.72	3.40	5.91
Significance (p)	.02	<.001	.01	.07	.02

Note. CISS–CON = Convergence Insufficiency Symptom Survey–Concussion Version; PD = prism diopters.

Break >20 PD or recovery >16 PD.

Group mean scores on the outcome measures (near point of convergence, amplitude of accommodation [for participants younger than age 40 yr], horizontal–vertical ratio from the Developmental Eye Movement Test, and the CISS–CON) were calculated to determine whether differences existed between participants with and without concussion. Of the outcome measures studied, near point of convergence (p = .003), positive fusional vergence (p = .04), and the CISS–CON (p = .00) had group means that were significantly worse in the concussion group. Group mean comparisons can be found in Table 3.

Table 3.

Comparison of Means on Screening Measures Between Concussion and Musculoskeletal Groups

Group Type or Statistical Test	Near Point of Convergence, cm	CISS–CON Score	Positive Fusional Vergence Breakpoint (Prism Diopters)	Amplitude of Accommodation (Diopters)	Developmental Eye Movement Test Ratio
37 Concussion (n = 20), M	10.6	42.11	20.37	8.88	1.15
Musculoskeletal (n = 19), M	3.7	20.32	30.06	10.70	1.16
Independent-samples t (df)	N/A	5.16 (36)	N/A	−1.56 (23)	−0.06 (37)
Mann–Whitney U	85.5	N/A	90.0	N/A	N/A
Significance (p)	.003	<.001	.04	.13	.96

Note. CISS–CON = Convergence Insufficiency Symptom Survey–Concussion Version; N/A = not applicable.

Impact of Injuries on Occupation

No significant difference was found between groups on mean performance (p = .15) and satisfaction scores (p = .34). In addition, the mean performance (p = .76) and satisfaction (p = .78) scores did not differ significantly between participants with a positive screen on a single outcome measure and those with no positive screens. However, the mean performance and satisfaction scores for participants with two or more positive screen scores were significantly lower, both within the concussion sample (Table 4) and across diagnostic groups.

Table 4.

Comparison of Mean COPM Performance and Satisfaction Scores Between Participants in the Concussion Group (n = 20) With and Without Two or More Positive Screens

COPM Score/≥2 Positive Screening Results	n (%)	M (SD)	SEM	t(38)	Significance (p)
Performance				3.21	.005
Yes	16 (80)	3.83 (1.25)	0.31
No	4 (20)	6.00 (0.98)	0.49
Satisfaction				3.33	.004
Yes	16 (80)	2.77 (1.37)	0.34
No	4 (20)	5.42 (1.64)	0.82

Note. COPM = Canadian Occupational Performance Measure.

Occupational Categories Affected

Responses on the COPM were labeled according to the types of occupations included in the measure. In total, 108 responses were provided, and up to 3 responses were permitted for each participant. The most frequent response types were active recreation (26%), paid or unpaid work (15%), and functional mobility (15%).

Response types were compared between participants with concussion and musculoskeletal injuries. The COPM categorizes nine response types into three broader occupational categories of self-care, productivity, and leisure. A χ² analysis of the response categories selected within participants’ top three occupational performance deficits did not reveal an overall significant difference between the groups with and without concussion (p = .07). Occupations in the productivity category (paid or unpaid work, household management, and school or play) were selected by 46% of participants in the concussion group, averaging more than one per participant. When analyzed on its own, difficulty with productivity was found to occur more frequently in the concussion group (46%) than in the musculoskeletal group (22%; p = .02). A comparison between participants with and without vision symptoms did not reveal a significant difference in productivity between these two groups (p = .70).

Discussion

Comparison of Positive Screen Frequency

A surprisingly high number of participants, both with (95%) and without (73%) concussion, failed at least one of the screening tests used. A few possible explanations can show why the difference in frequency of failure between these two groups was not statistically significant. First, failure on any single screening test is not necessarily an indication that a vision problem is present. A diagnostic battery of tests must take place after a screening to determine whether a problem exists.

Another possible explanation for the negative finding for single-test result prevalence is that the study’s sample size lacked the power to discriminate between groups when a difference did exist. The study was underpowered for the amplitude of accommodation, and this tool could only be measured on prepresbyopic participants (i.e., those younger than age 40 yr), resulting in a smaller sample size than the other measures.

When the prevalence of failure on at least two screening tests was compared, a considerable difference did exist between participants with and without concussion. Participants with concussion were significantly more likely to exhibit at least two signs or symptoms of visual disturbance than those with musculoskeletal injuries. The additive effect of failure of two or more vision screening tests is likely more clinically significant than the presence of a single failure. This finding supports Radomski et al.’s (2014) recommendation that a vision screening battery should use multiple measures.

Frequency of Vision Symptoms and Signs

The high frequency of participants with concussion with high scores on the CISS–CON, which addresses reading and close work in 17 of its 25 questions, aligns with Brahm et al.’s (2009) findings and exceeds Magone et al.’s (2014) findings. The high rate of endorsement of reading difficulty in this study may have been because of reading being addressed directly in the vision symptom survey. Remote break points on the near point of convergence test for participants with concussion in this study also align with results from the literature (Master et al., 2016; Scheiman et al., 2021), suggesting high rates of convergence insufficiency among people with concussion. According to Scheiman and Wick (2019), a receded near point of convergence is required, but not sufficient, for a diagnosis of convergence insufficiency.

This diagnosis can only be made by an optometrist or ophthalmologist and is, therefore, outside of the scope of occupational therapy; however, failure on this assessment is a strong indicator that a client may benefit from an assessment by an eye doctor. The mean near point of convergence breakpoint for the concussion group in this study is higher than the normal cutoff of 5 to 7 cm (Scheiman et al., 2003), whereas the mean for the musculoskeletal group is well within the normal range. Inadequate positive fusional vergence is another characteristic of convergence insufficiency (Rouse et al., 2004). Most participants with concussion in this study had reduced base-out or positive vergence scores on the BVA screener’s assessment, whereas only 25% of participants with musculoskeletal injuries showed this difficulty.

Of the visual symptoms screened in this study, those that showed a significant relationship with concussion were difficulties with convergence and positive fusional vergence, as well as reported difficulties with reading and close work, tasks that require sustained convergence. This finding supports the experience of poor reading tolerance by people with concussion, especially when working with small print or on mobile screens.

Impact of Visual Disturbances on Occupation

The primary objective of this research was to determine whether a relationship existed between visual signs and symptoms after concussion and low performance and satisfaction by comparing scores on the COPM. The occupations that affected participants with and without concussion, as well as with and without vision symptoms, were also examined. A significant difference in mean COPM performance and satisfaction scores was found between participants who failed two or more screening tests and those who did not. Participants with failure on two or more tests reported lower performance and satisfaction with up to three occupations that had been affected by their injuries, regardless of whether they had a concussion.

Occupational Categories Affected

Surprisingly, the presence or absence of visual signs and symptoms did not affect the types of occupations selected as areas of difficulty on the COPM. For example, participants from both groups selected sports as one of the occupations they were now less able to perform. This finding may have been related to context and environment because they completed the assessment at a sports medicine clinic.

One unanticipated difference found between the groups was the increased number of responses related to productivity (paid or unpaid work, school, and household management on the COPM) among participants with concussion, compared with those with musculoskeletal injuries. Although occupational balance is important for a healthy lifestyle, the occupations in the productivity category have potential economic implications for people in terms of lost time and shifts in family responsibilities. Further research is needed to explore the issue of productivity loss for people with concussion.

Limitations

Limitations of this study include the small sample size and single-site design because of time and resource constraints. This design made it difficult to do more in-depth analysis of other factors, such as injury severity or time since injury. Because the occupational therapist conducting the assessments was also the primary investigator, unintentional bias could have affected how the study was described during the consent process or how the semistructured interview of the COPM was conducted. Finally, because the injury types differed in the musculoskeletal group, no mechanism was used to record injury severity, which may have affected COPM performance and satisfaction results. In the future, it would be beneficial for researchers to replicate the results with a larger, multisite study using a more homogeneous control group. Therefore, the results should be interpreted within the limited scope of the study.

Implications for Occupational Therapy Practice

This study provides further evidence that clients with concussion are more likely than the general population or people with other injuries to experience performance deficits related to vision. Occupational therapy practitioners working with people with concussion or other neurological conditions that may affect visual efficiency should

inquire about symptoms of visual efficiency problems, including eye strain or worsening of headache when clients perform occupations with a high visual demand;

advocate for interprofessional collaboration and vision referrals required for the expertise of optometrists with specialized binocular vision training for comprehensive vision assessments; and

consider completing postprofessional or continuing education in the assessment of visual signs and symptoms because entry-level training is not adequate in this specialized area.

Occupational therapy practitioners are ideally situated to help clients identify occupational performance deficits related to vision changes. The most effective screening tools to differentiate those with and without concussion-related vision issues are near point of convergence, positive and negative fusional vergences, and the CISS–CON. Using these tools, occupational therapy practitioners can guide clients in need of comprehensive vision assessment and intervention services that might otherwise be missed in a standard postconcussion assessment.

Conclusion

Results suggest an increased frequency of vision screening failure among people with concussion when compared with those with musculoskeletal injuries. Self-reported occupational performance and satisfaction scores were reduced among people with and without concussion with two or more vision screening scores outside of the normal range. This finding suggests that people with reduced visual efficiency may experience poorer functional recovery from injury than those with less-compromised vision. These findings also support the need to explore a collaborative relationship among occupational therapy practitioners, optometrists, and ophthalmologists to assess and treat postconcussion vision disorders as well as to examine the personal and economic impact of productivity loss as a result of concussion.

Supplemental Material

Supplementary material for Comparison of Visual Symptom Frequency and Occupational Issues Between Patients With and Without Concussion

Supplementary material, sj-pdf-1-aot-10.5014_ajot.2024.050353.pdf for Comparison of Visual Symptom Frequency and Occupational Issues Between Patients With and Without Concussion by Stephanie Schurr, Caitlyn Foy, Tanya Polonenko and Mitchell Scheiman in The American Journal of Occupational Therapy

Footnotes

Acknowledgments

We thank the Learning and Development Department at St. Joseph’s Care Group for their contributions of funds and educational time for the completion of this research. We also thank Dr. David McKee for helping to host this study in his clinic and all of our participants.

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Supplementary Material

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