C L I N I C A L
A N D
E X P E R I M E N T A L
OPTOMETRY RESEARCH PAPER
Prevalence of visual problems among stroke survivors in Hong Kong Chinese Clin Exp Optom 2014; 97: 433–441 Kar Ho Siong* BSc (Optom) George C Woo* OD PhD Dora Yuk-Lin Chan† Msc in Health Care (Occupational Therapy) Kenneth Yiu Kwan Chung¶‡ B Med Sci, MBBS, MRCP (UK), FHKCP, FHKAM (Medicine) Leonard Sheung Wai Li§ MBBS (NSW), MRCP (UK), FACRM, FAFRM (RACP), FRCP (Edinburgh and London), FHKCP, FHKAM (Medicine) Hobby Kwong Yu Cheung‡ MBBS (HKU), MRCP (UK), FHKCP, FHKAM (Medicine) Claudia Kam Yuk Lai¶ PhD, PRegDip(N); RM (HK); RN (HK), SCM (UKCC), SRN (UKCC) Allen Ming Yan Cheong* PhD BSc (Optom) * School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China † Occupational Therapy Department, Kowloon Hospital Hospital Authority, Hong Kong, China § Division of Rehabilitation Medicine, Tung Wah Hospital Hospital Authority, Hong Kong, China ‡ Department of Rehabilitation, Kowloon Hospital Hospital Authority, Hong Kong, China ¶ School of Nursing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China E-mail: [email protected]
DOI:10.1111/cxo.12166 Background: Stroke, a common cerebrovascular accident, usually results in various extents of functional disability. Extensive studies have shown that ocular and visual problems are common in patients with stroke. Unfortunately, current stroke rehabilitation programs rarely address stroke-related ocular and visual problems in Hong Kong. Methods: To examine how visual impairment (for example, deterioration in visual acuity and restriction in visual field) affects the stroke population in Hong Kong, vision screening was conducted for post-stroke patients attending in-patient and out-patient stroke clinics at two hospitals. Results: One hundred and thirteen stroke patients were recruited. The percentage of various aspects of visual problems in Hong Kong post-stroke patients was generally lower than that reported in Western countries; however, a high percentage of patients had deficits in oculomotor (53.1 per cent) and vergence functions (11.5 per cent), restrictions in binocular visual field (11.5 per cent) and impairment in visual acuity (worse than 0.30 logMAR, 29.8 per cent). Conversely, only a small proportion of patients noticed problems with their vision (for example, diplopia and blurry vision) through subjective reports. This revealed that many post-stroke patients had undetected or undiagnosed ocular and visual problems. Appropriate referral was given to patients with visual problems for further evaluation and treatment. Conclusion: Neglecting visual problems may impose deteriorating effect on patients’ stroke rehabilitation and functional independence and lead to increased incidents of injury. To address this potential hindrance in rehabilitation, formal screening for visual problems in stroke patients in a rehabilitation setting is essential.
Submitted: 16 November 2013 Revised: 10 March 2014 Accepted for publication: 23 March 2014
Key words: binocular abnormalities, binocular vision, Hong Kong Chinese, oculomotor deficits, visual deficits, stroke Statistics provided by the Hong Kong Hospital Authority in the years 2010–2011 revealed that the total number of in-patients because of stroke was 3,490.1 According to the definition in the International Classification of Disease-10 (ICD-10) provided by the World Health Organization (WHO), stroke is a cerebrovascular disease associated with neurological defects. The main causes of stroke are due to infarction and ischaemia of the central nervous system (CNS), leading to blockage of vascular tissue of the brain resulting in hypoxia of the CNS. Such
hypoxic conditions compromise normal functioning controlled by different regions of the cortex (frontal, parietal, occipital and temporal lobe) and brain stem (external and internal capsule and intraventricular and periventricular areas). Because of the versatile and complex functions of brain tissue, several areas of functional performance in stroke patients are usually affected, namely, vision, speech, mobility and cognition. For example, damage to the temporal lobe could lead to deterioration in language, comprehension and logic understanding,
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
while damage in the occipital lobe could affect visual function. To minimise the negative impact of functional deficits on a patient’s quality of life, specific rehabilitation of these disability areas is essential.2–4 Depending on the location and extent of the damaged areas in the brain, many poststroke patients have various extents of functional disability, such as hemiplegia and hemianopia affecting body co-ordination and the visual field, respectively. Recently, several epidemiological studies have investigated the prevalence of visual impairments
Clinical and Experimental Optometry 97.5 September 2014
433
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
in stroke populations in Western countries.5–7 Findings12,13 suggested that 10 to 70 per cent of stroke patients had some level of visual impairment, such as deterioration in visual acuity (VA),8 visual field loss (for example, homonymous hemianopia and quadranopsia9), squint,10 eye movement disorders11 and perceptual deficits. Large discrepancies in the prevalence of visual impairment were mainly due to differences in recruitment sites and recruitment criteria. Some studies recruited patients from stroke rehabilitation centres and/or outpatient rehabilitation centres,14 stroke clinics and hospital emergency units,5,6 while another study recruited patients with selfreported visual deficits.15 Hence, comparing the prevalence of visual impairment in poststroke patients among various studies is difficult. To our knowledge, no similar epidemiological study has been undertaken in Hong Kong or other Asian countries to examine the prevalence of visual impairment associated with stroke. Despite the potential visual problems in stroke survivors, many visual deficits are asymptomatic or neglected, resulting in little or no management.13 Visual impairment has a deteriorating effect on a patient’s stroke rehabilitation, functional independence and quality of life.13,16,17 It can limit an individual’s self-care abilities such as walking independently, reading labels on medicine and managing personal finances. To minimise the potential impediment to stroke rehabilitation, early recognition of visual problems in stroke survivors is essential. Before proposing the implementation of assessment of vision in current stroke rehabilitation in Hong Kong, more information on the prevalence of visual impairment in stroke survivors is required. In this study, we conducted vision screenings at in-patient and out-patient clinics at two hospitals. Our first objective was to examine the characteristics of visual and functional deficits in poststroke survivors. Our second objective was to examine whether the visual characteristics would be different for post-stroke survivors at two stroke clinics with different recovery stages.
obtained in accordance with a protocol approved by The Hong Kong Polytechnic University Human Research Ethics Committee and the Institutional Review Board of Hospital Authority Hong Kong West Cluster and Kowloon Central Cluster. The study followed the tenets of the Declaration of Helsinki. A convenience sample of poststroke patients was recruited from patients attending the clinics. Participants with unstable medical conditions (for example, bedbound condition and loss of consciousness) were excluded. To confirm the integrity of cognitive function, only participants with mini-mental state examination (MMSE) scores above 18 were recruited.18,19
Demographic and clinical information In addition to basic demographic information (for example, age, gender and education level), clinical information, including stroke-related clinical information, general and ocular health, self-evaluation of their disability, mobility and functional performances were collected.
Vision and functional assessments Basic visual functions (including distance visual acuities, contrast sensitivity and visual fields), binocular vision and ocular health were examined under habitual viewing condition. Appendix 1 summarises the tests, corresponding equipment and outcome measures. All assessments were conducted by optometrists and optometry students under their supervision. Other than visual function, visual neglect and the effect of severity of the disability on functional performance were examined. The line bisection test was conducted for screening visual neglect.20,21 For functional performance, ‘functional independent measures’ (FIM) were administered by registered occupational therapists in both motor (FIM-motor) and cognition areas (FIM-cognitive).22,23 A seven-point scale is used for FIM, ranging from total assistance (Grade 1) to complete independence with no aids (Grade 7). Full score of the FIM-motor and FIM-cognitive was 91 and 35, respectively, with a total score of 126.
METHODS RESULTS Vision screenings for stroke patients were conducted at two hospitals: the out-patient stroke clinic at Hong Kong West Cluster (HKW) and the in-patient clinic at Kowloon Central Cluster (KC). Informed consent was
Demographic information One hundred and thirteen subjects (Hong Kong Chinese) were recruited from two
Clinical and Experimental Optometry 97.5 September 2014
434
stroke rehabilitation centres (64 from HKW and 49 from KC), with 49 females and mean age of 62.9 ± 13.8 years (age range of 22 to 89 years). Table 1A summarises the details of demographic information for stroke patients at HKW and KC. Despite the different natures of participants recruited at the two stroke centres, the majority of the demographic factors were not significantly different (p > 0.05). Most stroke patients (92.5 per cent) had at least one or more systemic diseases, such as hypertension (69.2 per cent), hyperlipidaemia (31.8 per cent), high cholesterol level (30.8 per cent) and diabetes mellitus (28 per cent). Other than the medications in managing the systemic diseases, 10.2 per cent of participants also took medications for depression and hypnotic drugs. Only 4.4 per cent of participants had a family history of stroke (HKW: 1.6 per cent and KC: 8.2 per cent). Table 1B summarises the medical history and current medications.
Clinical information on stroke characteristics The overall prevalence for right-sided and left-sided strokes were 38.3 and 56.1 per cent, respectively and 5.6 per cent were affected on both sides (Table 2). The number of left-side affected stroke was relatively higher, in particular in the KC with 20 per cent more cases. Onset time for primary and recurrent strokes ranged from 10 days to 26 years and seven days to 3.43 years for HKW and KC, respectively. Due to the nature of patients admitting to the KC (that is, an in-patient clinic), the duration of stroke in KC was significantly shorter than that in HKW (4.73 months versus 3.43 years). The aetiology of stroke was mainly due to ischaemia (41 per cent), infarction (34.3 per cent) and intracranial haemorrhage (22.9 per cent). Interestingly, the main cause of stroke in the two hospitals was very different, where the main aetiology was infarction at HKW (62.7 per cent) but ischaemia (72.3 per cent) at KC. The majority of strokes occurred in the cortical region (76 per cent) and brain stem (14 per cent), with the thalamus, basal ganglia and lacunar as the most commonly affected areas (34 per cent) (regions leading to significant functional impairment for patients with multiple affected areas was selected as the aetiology). Many patients (92.1 per cent) detected the occurrence of stroke because of the sudden onset of numbness and weakness on one side of the body either by themselves or by family members (HKW: 90.8 per cent and KC: © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
Age distribution (years)
HKW
KC
Overall
20–29
—
2.1
0.9
30–39
4.7
4.3
4.5
40–49
9.4
14.9
11.6
50–59
25
14.9
21.4
60–69
25
25.5
25.0
70–79
31
23.4
27.7
4.7
14.9
8.9
62.78 ± 12.29
62.85 ± 15.76
62.86 ± 13.80
(37 to 89 years)
(22 to 87 years)
(22 to 89 years)
80–89 Mean ± SD
29.4 per cent of patients reported having cataracts. In addition, some patients complained of floaters (31.2 per cent), epiphora (18.3 per cent) and dry eye (11 per cent). Interestingly, only KC patients complained of diplopia (15.2 per cent).
Prevalence of visual deficits in post-stroke survivors
Living conditions HKW
KC
Overall
Self-living
HKW
KC
Overall
7.9
13.0
10.1
With spouse and children
33.3
37.0
34.9
With spouse
33.3
13.0
24.8
With relatives and/or friends
—
13.0
5.5
With children
20.6
23.9
22
Others
4.8
—
2.8
Gender distribution
Male
HKW
KC
Overall
60.9
51.0
56.6
Female
HKW
KC
Overall
39.1
49.0
43.4
Table 1A. Demographic information on age distribution, living conditions and gender distribution (as a percentage)
General health problems HKW
KC
Overall
Hypertension
65
74.5
69.2
Diabetes mellitus
High cholesterol level
11.7
55.3
30.8
Depression
5
14.9
9.3
Heart disease
Hyper-lipidaemia
HKW
KC
Overall
26.7
29.8
1.7
6.4
3.7
38.3
23.4
31.8
HKW
KC
Overall
1.6
2.1
1.9
28
Drug-intake for general health problems HKW
KC
Overall
Hypertension
93.4
63.8
80.6
Analgesic use
Cholesterol level
16.4
61.7
36.1
Diuretic use
3.3
2.1
2.8
25.5
24.1
2.1
1.9
Heart problem Diabetes mellitus Vasodilator
23 1.6
4.9
6.4
5.6
Pain killer
16.4
2.1
10.2
Sedative drug
13.1
—
7.4
—
6.4
2.8
Psychiatric problem
Table 1B. Prevalence of general health problems and types of drug-intake (as a percentage) 93.9 per cent). Only six patients were identified with visual neglect (HKW: two and KC: four).
Self-reported history of eye examination and quality of vision Many participants (67.9 per cent) had eye examinations, among which the majority of the examinations were performed in
the pre-stroke period, while 33 per cent were conducted within the last year. Some patients received a dilated fundus examination (48.6 per cent), while 51.4 per cent had only a check-up for refraction (Table 3). Nearly 80 per cent of the population reported having clear distance (78.5 per cent) and near (78.1 per cent) vision. Despite relatively good self-reported vision,
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
In this study, distance VA in the better eye was chosen to represent an individual’s visual function because it could reasonably predict visual performance under binocular conditions.24 Distance VA and contrast sensitivity were 0.26 ± 0.26 logMAR and 1.92 ± 0.43 log-units, respectively, where there were no significant differences between the two hospital settings (p > 0.2) (Table 4). According to the definition by WHO,25 mild low vision is defined as VA worse than 0.50 logMAR (6/18), while moderate low vision is defined as VA worse than 1.0 logMAR (6/60) but better than 1.3 logMAR (6/120). The same criteria are also referenced in Hong Kong.26 Adopting this definition, 15 per cent (HKW: 9.4 per cent and KC: 22.4 per cent) and 1.8 per cent of patients (KC: 4.1 per cent) were classified as mild and moderate low vision, respectively. Adopting the same criteria of VA used in other relevant epidemiological studies, 29.8 per cent of the patients had VA worse than 0.30 logMAR.5,7 Visual impairment was mainly due to significant cataract (that is, grade 3 or above using LOCS III classification, 14.2 per cent), macular degeneration (4.4 per cent) and suspected cases of glaucoma (7.9 per cent). The remaining causes of visual impairment might be uncorrected refractive error. For the assessment of binocular vision, only five cases of concomitant exotropia were observed (one case in HKW and four cases in KC), with the deviation ranging from two to 45 prism-dioptres. The median stereo-acuity was 70 seconds of arc (IQR: 20 seconds of arc), with no significant difference between hospitals (z = -0.28, p = 0.78). The median near point of convergence was 70 cm (IQR: 20 cm), in which patients in the HKW outperformed those in the KC (39.79 cm versus 64.7 cm, z = -4.31, p < 0.001). Twenty-one per cent of KC patients had a near point of convergence of 15 cm or worse (equivalent to about six dioptres of accommodation). In eye movement evaluation, 11.5 per cent and 53.1 per cent of patients had at least one eye identified with restriction of ocular motility (HKW: 9.3 per
Clinical and Experimental Optometry 97.5 September 2014
435
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
HKW Stroke Side of hemi-plasia involved
KC
Overall
Primary
88.5
83
86.1
Recurrent
11.5
17
13.9
Right
45
29.8
38.3
Left
55
57.4
56.1
Both
—
12.8
5.6
41 days to 26 years
10 days to 9.62 years
10 days to 26 years 7 days to 3.43 years
Duration
Primary stroke
4.73 months to 3.43 years
7 days to 43 days
Aetiology of stroke
Ischaemia
15.5
72.3
41
Intracranial haemorrhage
20.7
25.5
22.9
—
2.1
1
Recurrent stroke
Subarachnoid haemorrhage Infarction
62.7
—
34.3
Unknown
1.7
—
1
HKW Type of stroke
Location of stroke (%)
KC
Overall
Cortical
68.4
86
76
Brain-stem
14
14
14
Other areas
17.5
—
10
Frontal
28.6
9.1
20
Parietal
5.4
2.3
4
Temporal
—
4.5
2
Occipital
3.6
4.5
4
26.8
11.4
20
Lobe
External and internal capsule Intraventricular & periventricular areas
5.4
Thalamus, basal ganglia and lacunar areas
21.4
Others
8.9
9.1 50 9.1
7 34 9
Table 2. Stroke-related medical history at HKW and KC (as a percentage) cent and KC: 14.3 per cent) and jerky movement (HKW: 75.8 per cent and KC: 20.6 per cent), respectively. In visual field assessment, 26.5 per cent of patients (HKW: 31.2 per cent and KC: 20.4 per cent) had monocular field defects but only 11.5 per cent of patients (HKW: 18.8 per cent and KC: 10.2 per cent) had binocular field defects. To further categorise the type of field defect, 20.2 per cent and 22.6 per cent had a visual field loss occurring on the right (HKW: 16.9 per cent and KC: 24.6 per cent) and left (HKW: 27.7 per cent and KC: 16.3 per cent) sides, respectively. Some levels of cataract on either eye were found in 57.8 per cent of patients (HKW: 56.8 per cent and KC: 59.2 per cent); however, only 14.2 per cent of the cataracts (HKW: 20 per cent and KC: 6.1 per cent) were classified as grade 3 or more, resulting in visual loss. Regarding the subtypes of cataract, the prevalences of nuclear sclerosis, cortical and posterior subcapsular cataract
were 36.3 per cent, 17.7 per cent and 34.5 per cent, respectively. For external ocular abnormalities, conjunctival degeneration (pinguecula and pterygium) and ptosis were more commonly found, affecting 19.9 per cent and 7.9 per cent of the population. For internal ocular abnormalities, eight per cent of patients were suspected of having glaucoma (due to high intra-ocular pressure and large cup-disc ratio in the optic disc) and 4.4 per cent of patients were suspected of having agerelated macular degeneration. Patients with suspected ocular diseases were referred to optometrists or ophthalmologists for further examination.
Disability on functional performance Disability on functional performance, including motor and cognitive functions was examined for individual participants
Clinical and Experimental Optometry 97.5 September 2014
436
using functional independent measures (Table 5). The total functional independent measures score was 93.53 ± 22.74, with significantly better performance for patients in HKW than in KC (p < 0.001). Details of the sub-scores in FIM-motor and FIM-cognition are summarised in Table 5. The sub-score for the cognition section was 30.02 ± 4.91, which was in line with the insignificant difference in the MMSE score between the two stroke centres (t = 1.86, p = 0.07). Figure 1 shows the mean functional independent measures total scores in participants with and without restriction of eye movement and visual field defect. A significant difference in the mean functional independent measures score was found in participants with restriction in eye movement (t = 2.74, p = 0.008) but not in participants with visual field defects (t = -0.62, p = 0.54). This indicated that a lower functional independent measures score corresponded to deteriorated eye movements. © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
Last eye examination
Nature of eye examination HKW
KC
Overall
No eye check before
38.1
23.9
32.1
3 years
22.2
13
7.3
10.9
HKW
KC
Overall
Refraction checkup
31.7
42.9
51.4
Dilated fundus examination
30.2
40.5
48.6
17.4
Self-evaluation on visual clarity
Distance vision Near vision
HKW
KC
Overall
Clear
83.9
71.1
78.5
Blur
16.1
28.9
21.3
Clear
88.7
62.8
78.1
Blur
11.3
37.2
21.7
Self-reported ocular symptoms HKW
KC
Overall
Dry eye
11.1
10.9
Red eye
3.2
8.7
5.5
Diplopia
Eye pain
9.5
8.7
9.2
Flash
11
HKW Floaters
Photophobia
11.1
6.5
9.2
Tearing
17.5
19.6
18.3
27
KC 37
Overall 31.2
—
15.2
6.4
11.1
8.7
10.1
Meta-morphopsia
1.6
2.2
1.8
Head tilt
3.1
4.3
3.7
Self-reported ocular problems HKW
KC
Overall
Cataract
27
32.6
29.4
Glaucoma
1.6
2.2
1.8
Age-related macular degeneration
—
2.2
0.9
HKW
KC
Overall
Diabetic retinopathy
1.6
2.2
1.8
Retinal detachment
—
4.3
1.8
Table 3. History of eye examinations and prevalence of reported ocular diseases (as a percentage)
DISCUSSION Stroke affects multiple areas of the brain, which may result in different types of disabilities in sensory and motor performance (for example, interaction of sensory and motor signals in the thalamus; voluntary motor control, execution of procedural learning and emotional control in the basal ganglia). Some impaired functions such as balance27,28 and motor systems29,30 can be recovered in the post-stroke period; however, the progress of recovery depends not only on the extent of the damage from the stroke but also the amount of training and rehabilitation to activate the recovery process. Unfortunately, many stroke rehabilitation programs, including those in Hong Kong, rarely address stroke-related visual problems unless the patients complain
of having visual deficits.31,32 Neglecting these visual problems may impose a detrimental effect on patients’ stroke rehabilitation and functional independence and leads to increased incidents of injury. Impaired vision is a significant factor contributing to falls and hip fractures.33–35 Early detection of any visual deficits and appropriate interventions are vital to improve patients’ functional performances and prevent accidental injury.
High prevalence of visual problems in the post-stroke population Incidence of stroke might distract the attention of visual problems and thus most participants did not report any visual problems in our current study. Our study found that 15 and 11.5 per cent of patients had mild low
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
vision (that is, VA less than 0.50 logMAR) and binocular visual field defects, respectively. Although there were only 4.4 per cent of patients (five cases) having exotropia, a large percentage of patients had abnormalities in ocular movements and/or binocular vision with 53.1 per cent of stroke patients having jerky eye movements and 11.5 per cent of patients having restricted ocular movement. About 20 per cent of the patients had reduced convergence. Such deficits in ocular motor control and binocular vision may result in impairment in fine motor co-ordination (for example, poor eyehand co-ordination), reading problems (for example, loss of place or words appear to be jumping or moving while reading) and double vision. It should be noted that the visual performance in KC was poorer than that in HKW because of a difference in the
Clinical and Experimental Optometry 97.5 September 2014
437
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
HKW RE
KC
LE
BE
RE
LE
BE
Habitual distance VA (logMAR)
0.35 ± 0.27
0.27 ± 0.26
0.23 ± 0.23
0.33 ± 0.32
0.36 ± 0.29
0.29 ± 0.31
Intraocular pressure (mmHg)
14.98 ± 3.97
14.08 ± 3.75
—
15.03 ± 3.29
13.51 ± 3.51
—
RE
Restriction
7.9
RE
Restriction
6.1
LE
Restriction
LE
Restriction
14.3
Jerky movement
20.4
EE
Restriction
14.3
Jerky movement
20.6
RE
Right
Ocular motility
Jerky movement
75.6 7.9
Jerky movement EE
Restriction
RE
Right
74.2 9.3
Jerky movement Visual field loss (%)
Jerky movement
75.8 7.8
Left
18.8
LE
Right
14.1
Left
20.3
EE
Right
16.9
Left
27.7
Left LE EE
16.3
6.1 4.1
Right
14.3
Left
12.2
Right
24.6
Left
16.3
RE: right eye, LE: left eye, BE: better eye, EE: either eye, VA: visual acuity.
Table 4. Prevalence of visual deficits, visual acuity, intra-ocular pressure, ocular motility and visual field restriction
Sub-score in FIM-motor HKW
KC
Mann-Whitney test
Overall
Self care
34.04 ± 9.49
29.15 ± 8.41
z = -3.146*
31.54 ± 9.24
Sphincter control
11.82 ± 3.49
10.17 ± 3.49
z = -2.021*
10.98 ± 3.57
Mobility
16.51 ± 5.50
11.87 ± 4.53
z = -4.363**
14.14 ± 5.52
9.49 ± 4.44
7.51 ± 6.71
z = -3.123*
8.48 ± 5.77
71.87 ± 20.61
55.60 ± 17.54
z = -3.953**
64.01 ± 20.76
Locomotion Motor session
Sub-score in FIM-cognition HKW
KC
Mann-Whitney test
Overall
Cognition session
30.00 ± 5.83
30.04 ± 3.88
z = -0.696
30.02 ± 4.91
Total score for FIM
101.40 ± 23.22
85.83 ± 19.60
z = -3.748**
93.53 ± 22.74
*Represents p < 0.05, ** represents p < 0.001 FIM: functional independent measures
Table 5. Performance in functional independent measures in motor and cognition sessions. Values show mean ± standard deviation
nature of the stroke clinic, where KC was the in-patient clinic and it accommodated patients with recent stroke (revealed by the shorter onset time of primary stroke, Table 2) and requirement of a greater number of drugs for general health issues (Table 1B).
Despite a relatively small sample in this study, our participants represented a good sampling of the post-stroke population in Hong Kong because the aetiology of stroke subtypes in our study was similar to a recent study, which investigated the trend of stroke incidences in Hong Kong.32 Results from
Clinical and Experimental Optometry 97.5 September 2014
438
both studies revealed that the major cause of stroke was ischaemia, followed by infarction. In terms of the locations of stroke or affected areas, the most commonly affected areas in our sample were frontal lobe (20 per cent), external and internal capsule (20 per cent) and thalamus, basal ganglia and lacunar areas (34 per cent). Damage in these areas results in different levels of functional impairment, including vision-related deficits.8,9,11 For example, the centre for controlling eye movement- in pre-motor and motor areas and the centre for vergence are located near the frontal lobe.36 Hence, a deficiency in the frontal lobe might lead to difficulty in controlling saccadic eye movements and poor vergence in binocular vision, resulting in jerky movements in ocular motility, restriction in ocular movements and poor convergence. Damage to the thalamus, basal ganglia and lacunar areas might be associated with oculomotor deficits because they are responsible for transferring information from sensory organs to the cerebral cortex via interneurones and the centre of connection in ascending and descending pathways.37 Thus, a significantly lower functional independent measures total score was identified in participants with deficit in eye movements, rather than the visual field. © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
140 p
A N D
E X P E R I M E N T A L
OPTOMETRY RESEARCH PAPER
Prevalence of visual problems among stroke survivors in Hong Kong Chinese Clin Exp Optom 2014; 97: 433–441 Kar Ho Siong* BSc (Optom) George C Woo* OD PhD Dora Yuk-Lin Chan† Msc in Health Care (Occupational Therapy) Kenneth Yiu Kwan Chung¶‡ B Med Sci, MBBS, MRCP (UK), FHKCP, FHKAM (Medicine) Leonard Sheung Wai Li§ MBBS (NSW), MRCP (UK), FACRM, FAFRM (RACP), FRCP (Edinburgh and London), FHKCP, FHKAM (Medicine) Hobby Kwong Yu Cheung‡ MBBS (HKU), MRCP (UK), FHKCP, FHKAM (Medicine) Claudia Kam Yuk Lai¶ PhD, PRegDip(N); RM (HK); RN (HK), SCM (UKCC), SRN (UKCC) Allen Ming Yan Cheong* PhD BSc (Optom) * School of Optometry, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China † Occupational Therapy Department, Kowloon Hospital Hospital Authority, Hong Kong, China § Division of Rehabilitation Medicine, Tung Wah Hospital Hospital Authority, Hong Kong, China ‡ Department of Rehabilitation, Kowloon Hospital Hospital Authority, Hong Kong, China ¶ School of Nursing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China E-mail: [email protected]
DOI:10.1111/cxo.12166 Background: Stroke, a common cerebrovascular accident, usually results in various extents of functional disability. Extensive studies have shown that ocular and visual problems are common in patients with stroke. Unfortunately, current stroke rehabilitation programs rarely address stroke-related ocular and visual problems in Hong Kong. Methods: To examine how visual impairment (for example, deterioration in visual acuity and restriction in visual field) affects the stroke population in Hong Kong, vision screening was conducted for post-stroke patients attending in-patient and out-patient stroke clinics at two hospitals. Results: One hundred and thirteen stroke patients were recruited. The percentage of various aspects of visual problems in Hong Kong post-stroke patients was generally lower than that reported in Western countries; however, a high percentage of patients had deficits in oculomotor (53.1 per cent) and vergence functions (11.5 per cent), restrictions in binocular visual field (11.5 per cent) and impairment in visual acuity (worse than 0.30 logMAR, 29.8 per cent). Conversely, only a small proportion of patients noticed problems with their vision (for example, diplopia and blurry vision) through subjective reports. This revealed that many post-stroke patients had undetected or undiagnosed ocular and visual problems. Appropriate referral was given to patients with visual problems for further evaluation and treatment. Conclusion: Neglecting visual problems may impose deteriorating effect on patients’ stroke rehabilitation and functional independence and lead to increased incidents of injury. To address this potential hindrance in rehabilitation, formal screening for visual problems in stroke patients in a rehabilitation setting is essential.
Submitted: 16 November 2013 Revised: 10 March 2014 Accepted for publication: 23 March 2014
Key words: binocular abnormalities, binocular vision, Hong Kong Chinese, oculomotor deficits, visual deficits, stroke Statistics provided by the Hong Kong Hospital Authority in the years 2010–2011 revealed that the total number of in-patients because of stroke was 3,490.1 According to the definition in the International Classification of Disease-10 (ICD-10) provided by the World Health Organization (WHO), stroke is a cerebrovascular disease associated with neurological defects. The main causes of stroke are due to infarction and ischaemia of the central nervous system (CNS), leading to blockage of vascular tissue of the brain resulting in hypoxia of the CNS. Such
hypoxic conditions compromise normal functioning controlled by different regions of the cortex (frontal, parietal, occipital and temporal lobe) and brain stem (external and internal capsule and intraventricular and periventricular areas). Because of the versatile and complex functions of brain tissue, several areas of functional performance in stroke patients are usually affected, namely, vision, speech, mobility and cognition. For example, damage to the temporal lobe could lead to deterioration in language, comprehension and logic understanding,
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
while damage in the occipital lobe could affect visual function. To minimise the negative impact of functional deficits on a patient’s quality of life, specific rehabilitation of these disability areas is essential.2–4 Depending on the location and extent of the damaged areas in the brain, many poststroke patients have various extents of functional disability, such as hemiplegia and hemianopia affecting body co-ordination and the visual field, respectively. Recently, several epidemiological studies have investigated the prevalence of visual impairments
Clinical and Experimental Optometry 97.5 September 2014
433
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
in stroke populations in Western countries.5–7 Findings12,13 suggested that 10 to 70 per cent of stroke patients had some level of visual impairment, such as deterioration in visual acuity (VA),8 visual field loss (for example, homonymous hemianopia and quadranopsia9), squint,10 eye movement disorders11 and perceptual deficits. Large discrepancies in the prevalence of visual impairment were mainly due to differences in recruitment sites and recruitment criteria. Some studies recruited patients from stroke rehabilitation centres and/or outpatient rehabilitation centres,14 stroke clinics and hospital emergency units,5,6 while another study recruited patients with selfreported visual deficits.15 Hence, comparing the prevalence of visual impairment in poststroke patients among various studies is difficult. To our knowledge, no similar epidemiological study has been undertaken in Hong Kong or other Asian countries to examine the prevalence of visual impairment associated with stroke. Despite the potential visual problems in stroke survivors, many visual deficits are asymptomatic or neglected, resulting in little or no management.13 Visual impairment has a deteriorating effect on a patient’s stroke rehabilitation, functional independence and quality of life.13,16,17 It can limit an individual’s self-care abilities such as walking independently, reading labels on medicine and managing personal finances. To minimise the potential impediment to stroke rehabilitation, early recognition of visual problems in stroke survivors is essential. Before proposing the implementation of assessment of vision in current stroke rehabilitation in Hong Kong, more information on the prevalence of visual impairment in stroke survivors is required. In this study, we conducted vision screenings at in-patient and out-patient clinics at two hospitals. Our first objective was to examine the characteristics of visual and functional deficits in poststroke survivors. Our second objective was to examine whether the visual characteristics would be different for post-stroke survivors at two stroke clinics with different recovery stages.
obtained in accordance with a protocol approved by The Hong Kong Polytechnic University Human Research Ethics Committee and the Institutional Review Board of Hospital Authority Hong Kong West Cluster and Kowloon Central Cluster. The study followed the tenets of the Declaration of Helsinki. A convenience sample of poststroke patients was recruited from patients attending the clinics. Participants with unstable medical conditions (for example, bedbound condition and loss of consciousness) were excluded. To confirm the integrity of cognitive function, only participants with mini-mental state examination (MMSE) scores above 18 were recruited.18,19
Demographic and clinical information In addition to basic demographic information (for example, age, gender and education level), clinical information, including stroke-related clinical information, general and ocular health, self-evaluation of their disability, mobility and functional performances were collected.
Vision and functional assessments Basic visual functions (including distance visual acuities, contrast sensitivity and visual fields), binocular vision and ocular health were examined under habitual viewing condition. Appendix 1 summarises the tests, corresponding equipment and outcome measures. All assessments were conducted by optometrists and optometry students under their supervision. Other than visual function, visual neglect and the effect of severity of the disability on functional performance were examined. The line bisection test was conducted for screening visual neglect.20,21 For functional performance, ‘functional independent measures’ (FIM) were administered by registered occupational therapists in both motor (FIM-motor) and cognition areas (FIM-cognitive).22,23 A seven-point scale is used for FIM, ranging from total assistance (Grade 1) to complete independence with no aids (Grade 7). Full score of the FIM-motor and FIM-cognitive was 91 and 35, respectively, with a total score of 126.
METHODS RESULTS Vision screenings for stroke patients were conducted at two hospitals: the out-patient stroke clinic at Hong Kong West Cluster (HKW) and the in-patient clinic at Kowloon Central Cluster (KC). Informed consent was
Demographic information One hundred and thirteen subjects (Hong Kong Chinese) were recruited from two
Clinical and Experimental Optometry 97.5 September 2014
434
stroke rehabilitation centres (64 from HKW and 49 from KC), with 49 females and mean age of 62.9 ± 13.8 years (age range of 22 to 89 years). Table 1A summarises the details of demographic information for stroke patients at HKW and KC. Despite the different natures of participants recruited at the two stroke centres, the majority of the demographic factors were not significantly different (p > 0.05). Most stroke patients (92.5 per cent) had at least one or more systemic diseases, such as hypertension (69.2 per cent), hyperlipidaemia (31.8 per cent), high cholesterol level (30.8 per cent) and diabetes mellitus (28 per cent). Other than the medications in managing the systemic diseases, 10.2 per cent of participants also took medications for depression and hypnotic drugs. Only 4.4 per cent of participants had a family history of stroke (HKW: 1.6 per cent and KC: 8.2 per cent). Table 1B summarises the medical history and current medications.
Clinical information on stroke characteristics The overall prevalence for right-sided and left-sided strokes were 38.3 and 56.1 per cent, respectively and 5.6 per cent were affected on both sides (Table 2). The number of left-side affected stroke was relatively higher, in particular in the KC with 20 per cent more cases. Onset time for primary and recurrent strokes ranged from 10 days to 26 years and seven days to 3.43 years for HKW and KC, respectively. Due to the nature of patients admitting to the KC (that is, an in-patient clinic), the duration of stroke in KC was significantly shorter than that in HKW (4.73 months versus 3.43 years). The aetiology of stroke was mainly due to ischaemia (41 per cent), infarction (34.3 per cent) and intracranial haemorrhage (22.9 per cent). Interestingly, the main cause of stroke in the two hospitals was very different, where the main aetiology was infarction at HKW (62.7 per cent) but ischaemia (72.3 per cent) at KC. The majority of strokes occurred in the cortical region (76 per cent) and brain stem (14 per cent), with the thalamus, basal ganglia and lacunar as the most commonly affected areas (34 per cent) (regions leading to significant functional impairment for patients with multiple affected areas was selected as the aetiology). Many patients (92.1 per cent) detected the occurrence of stroke because of the sudden onset of numbness and weakness on one side of the body either by themselves or by family members (HKW: 90.8 per cent and KC: © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
Age distribution (years)
HKW
KC
Overall
20–29
—
2.1
0.9
30–39
4.7
4.3
4.5
40–49
9.4
14.9
11.6
50–59
25
14.9
21.4
60–69
25
25.5
25.0
70–79
31
23.4
27.7
4.7
14.9
8.9
62.78 ± 12.29
62.85 ± 15.76
62.86 ± 13.80
(37 to 89 years)
(22 to 87 years)
(22 to 89 years)
80–89 Mean ± SD
29.4 per cent of patients reported having cataracts. In addition, some patients complained of floaters (31.2 per cent), epiphora (18.3 per cent) and dry eye (11 per cent). Interestingly, only KC patients complained of diplopia (15.2 per cent).
Prevalence of visual deficits in post-stroke survivors
Living conditions HKW
KC
Overall
Self-living
HKW
KC
Overall
7.9
13.0
10.1
With spouse and children
33.3
37.0
34.9
With spouse
33.3
13.0
24.8
With relatives and/or friends
—
13.0
5.5
With children
20.6
23.9
22
Others
4.8
—
2.8
Gender distribution
Male
HKW
KC
Overall
60.9
51.0
56.6
Female
HKW
KC
Overall
39.1
49.0
43.4
Table 1A. Demographic information on age distribution, living conditions and gender distribution (as a percentage)
General health problems HKW
KC
Overall
Hypertension
65
74.5
69.2
Diabetes mellitus
High cholesterol level
11.7
55.3
30.8
Depression
5
14.9
9.3
Heart disease
Hyper-lipidaemia
HKW
KC
Overall
26.7
29.8
1.7
6.4
3.7
38.3
23.4
31.8
HKW
KC
Overall
1.6
2.1
1.9
28
Drug-intake for general health problems HKW
KC
Overall
Hypertension
93.4
63.8
80.6
Analgesic use
Cholesterol level
16.4
61.7
36.1
Diuretic use
3.3
2.1
2.8
25.5
24.1
2.1
1.9
Heart problem Diabetes mellitus Vasodilator
23 1.6
4.9
6.4
5.6
Pain killer
16.4
2.1
10.2
Sedative drug
13.1
—
7.4
—
6.4
2.8
Psychiatric problem
Table 1B. Prevalence of general health problems and types of drug-intake (as a percentage) 93.9 per cent). Only six patients were identified with visual neglect (HKW: two and KC: four).
Self-reported history of eye examination and quality of vision Many participants (67.9 per cent) had eye examinations, among which the majority of the examinations were performed in
the pre-stroke period, while 33 per cent were conducted within the last year. Some patients received a dilated fundus examination (48.6 per cent), while 51.4 per cent had only a check-up for refraction (Table 3). Nearly 80 per cent of the population reported having clear distance (78.5 per cent) and near (78.1 per cent) vision. Despite relatively good self-reported vision,
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
In this study, distance VA in the better eye was chosen to represent an individual’s visual function because it could reasonably predict visual performance under binocular conditions.24 Distance VA and contrast sensitivity were 0.26 ± 0.26 logMAR and 1.92 ± 0.43 log-units, respectively, where there were no significant differences between the two hospital settings (p > 0.2) (Table 4). According to the definition by WHO,25 mild low vision is defined as VA worse than 0.50 logMAR (6/18), while moderate low vision is defined as VA worse than 1.0 logMAR (6/60) but better than 1.3 logMAR (6/120). The same criteria are also referenced in Hong Kong.26 Adopting this definition, 15 per cent (HKW: 9.4 per cent and KC: 22.4 per cent) and 1.8 per cent of patients (KC: 4.1 per cent) were classified as mild and moderate low vision, respectively. Adopting the same criteria of VA used in other relevant epidemiological studies, 29.8 per cent of the patients had VA worse than 0.30 logMAR.5,7 Visual impairment was mainly due to significant cataract (that is, grade 3 or above using LOCS III classification, 14.2 per cent), macular degeneration (4.4 per cent) and suspected cases of glaucoma (7.9 per cent). The remaining causes of visual impairment might be uncorrected refractive error. For the assessment of binocular vision, only five cases of concomitant exotropia were observed (one case in HKW and four cases in KC), with the deviation ranging from two to 45 prism-dioptres. The median stereo-acuity was 70 seconds of arc (IQR: 20 seconds of arc), with no significant difference between hospitals (z = -0.28, p = 0.78). The median near point of convergence was 70 cm (IQR: 20 cm), in which patients in the HKW outperformed those in the KC (39.79 cm versus 64.7 cm, z = -4.31, p < 0.001). Twenty-one per cent of KC patients had a near point of convergence of 15 cm or worse (equivalent to about six dioptres of accommodation). In eye movement evaluation, 11.5 per cent and 53.1 per cent of patients had at least one eye identified with restriction of ocular motility (HKW: 9.3 per
Clinical and Experimental Optometry 97.5 September 2014
435
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
HKW Stroke Side of hemi-plasia involved
KC
Overall
Primary
88.5
83
86.1
Recurrent
11.5
17
13.9
Right
45
29.8
38.3
Left
55
57.4
56.1
Both
—
12.8
5.6
41 days to 26 years
10 days to 9.62 years
10 days to 26 years 7 days to 3.43 years
Duration
Primary stroke
4.73 months to 3.43 years
7 days to 43 days
Aetiology of stroke
Ischaemia
15.5
72.3
41
Intracranial haemorrhage
20.7
25.5
22.9
—
2.1
1
Recurrent stroke
Subarachnoid haemorrhage Infarction
62.7
—
34.3
Unknown
1.7
—
1
HKW Type of stroke
Location of stroke (%)
KC
Overall
Cortical
68.4
86
76
Brain-stem
14
14
14
Other areas
17.5
—
10
Frontal
28.6
9.1
20
Parietal
5.4
2.3
4
Temporal
—
4.5
2
Occipital
3.6
4.5
4
26.8
11.4
20
Lobe
External and internal capsule Intraventricular & periventricular areas
5.4
Thalamus, basal ganglia and lacunar areas
21.4
Others
8.9
9.1 50 9.1
7 34 9
Table 2. Stroke-related medical history at HKW and KC (as a percentage) cent and KC: 14.3 per cent) and jerky movement (HKW: 75.8 per cent and KC: 20.6 per cent), respectively. In visual field assessment, 26.5 per cent of patients (HKW: 31.2 per cent and KC: 20.4 per cent) had monocular field defects but only 11.5 per cent of patients (HKW: 18.8 per cent and KC: 10.2 per cent) had binocular field defects. To further categorise the type of field defect, 20.2 per cent and 22.6 per cent had a visual field loss occurring on the right (HKW: 16.9 per cent and KC: 24.6 per cent) and left (HKW: 27.7 per cent and KC: 16.3 per cent) sides, respectively. Some levels of cataract on either eye were found in 57.8 per cent of patients (HKW: 56.8 per cent and KC: 59.2 per cent); however, only 14.2 per cent of the cataracts (HKW: 20 per cent and KC: 6.1 per cent) were classified as grade 3 or more, resulting in visual loss. Regarding the subtypes of cataract, the prevalences of nuclear sclerosis, cortical and posterior subcapsular cataract
were 36.3 per cent, 17.7 per cent and 34.5 per cent, respectively. For external ocular abnormalities, conjunctival degeneration (pinguecula and pterygium) and ptosis were more commonly found, affecting 19.9 per cent and 7.9 per cent of the population. For internal ocular abnormalities, eight per cent of patients were suspected of having glaucoma (due to high intra-ocular pressure and large cup-disc ratio in the optic disc) and 4.4 per cent of patients were suspected of having agerelated macular degeneration. Patients with suspected ocular diseases were referred to optometrists or ophthalmologists for further examination.
Disability on functional performance Disability on functional performance, including motor and cognitive functions was examined for individual participants
Clinical and Experimental Optometry 97.5 September 2014
436
using functional independent measures (Table 5). The total functional independent measures score was 93.53 ± 22.74, with significantly better performance for patients in HKW than in KC (p < 0.001). Details of the sub-scores in FIM-motor and FIM-cognition are summarised in Table 5. The sub-score for the cognition section was 30.02 ± 4.91, which was in line with the insignificant difference in the MMSE score between the two stroke centres (t = 1.86, p = 0.07). Figure 1 shows the mean functional independent measures total scores in participants with and without restriction of eye movement and visual field defect. A significant difference in the mean functional independent measures score was found in participants with restriction in eye movement (t = 2.74, p = 0.008) but not in participants with visual field defects (t = -0.62, p = 0.54). This indicated that a lower functional independent measures score corresponded to deteriorated eye movements. © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
Last eye examination
Nature of eye examination HKW
KC
Overall
No eye check before
38.1
23.9
32.1
3 years
22.2
13
7.3
10.9
HKW
KC
Overall
Refraction checkup
31.7
42.9
51.4
Dilated fundus examination
30.2
40.5
48.6
17.4
Self-evaluation on visual clarity
Distance vision Near vision
HKW
KC
Overall
Clear
83.9
71.1
78.5
Blur
16.1
28.9
21.3
Clear
88.7
62.8
78.1
Blur
11.3
37.2
21.7
Self-reported ocular symptoms HKW
KC
Overall
Dry eye
11.1
10.9
Red eye
3.2
8.7
5.5
Diplopia
Eye pain
9.5
8.7
9.2
Flash
11
HKW Floaters
Photophobia
11.1
6.5
9.2
Tearing
17.5
19.6
18.3
27
KC 37
Overall 31.2
—
15.2
6.4
11.1
8.7
10.1
Meta-morphopsia
1.6
2.2
1.8
Head tilt
3.1
4.3
3.7
Self-reported ocular problems HKW
KC
Overall
Cataract
27
32.6
29.4
Glaucoma
1.6
2.2
1.8
Age-related macular degeneration
—
2.2
0.9
HKW
KC
Overall
Diabetic retinopathy
1.6
2.2
1.8
Retinal detachment
—
4.3
1.8
Table 3. History of eye examinations and prevalence of reported ocular diseases (as a percentage)
DISCUSSION Stroke affects multiple areas of the brain, which may result in different types of disabilities in sensory and motor performance (for example, interaction of sensory and motor signals in the thalamus; voluntary motor control, execution of procedural learning and emotional control in the basal ganglia). Some impaired functions such as balance27,28 and motor systems29,30 can be recovered in the post-stroke period; however, the progress of recovery depends not only on the extent of the damage from the stroke but also the amount of training and rehabilitation to activate the recovery process. Unfortunately, many stroke rehabilitation programs, including those in Hong Kong, rarely address stroke-related visual problems unless the patients complain
of having visual deficits.31,32 Neglecting these visual problems may impose a detrimental effect on patients’ stroke rehabilitation and functional independence and leads to increased incidents of injury. Impaired vision is a significant factor contributing to falls and hip fractures.33–35 Early detection of any visual deficits and appropriate interventions are vital to improve patients’ functional performances and prevent accidental injury.
High prevalence of visual problems in the post-stroke population Incidence of stroke might distract the attention of visual problems and thus most participants did not report any visual problems in our current study. Our study found that 15 and 11.5 per cent of patients had mild low
© 2014 The Authors Clinical and Experimental Optometry © 2014 Optometrists Association Australia
vision (that is, VA less than 0.50 logMAR) and binocular visual field defects, respectively. Although there were only 4.4 per cent of patients (five cases) having exotropia, a large percentage of patients had abnormalities in ocular movements and/or binocular vision with 53.1 per cent of stroke patients having jerky eye movements and 11.5 per cent of patients having restricted ocular movement. About 20 per cent of the patients had reduced convergence. Such deficits in ocular motor control and binocular vision may result in impairment in fine motor co-ordination (for example, poor eyehand co-ordination), reading problems (for example, loss of place or words appear to be jumping or moving while reading) and double vision. It should be noted that the visual performance in KC was poorer than that in HKW because of a difference in the
Clinical and Experimental Optometry 97.5 September 2014
437
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
HKW RE
KC
LE
BE
RE
LE
BE
Habitual distance VA (logMAR)
0.35 ± 0.27
0.27 ± 0.26
0.23 ± 0.23
0.33 ± 0.32
0.36 ± 0.29
0.29 ± 0.31
Intraocular pressure (mmHg)
14.98 ± 3.97
14.08 ± 3.75
—
15.03 ± 3.29
13.51 ± 3.51
—
RE
Restriction
7.9
RE
Restriction
6.1
LE
Restriction
LE
Restriction
14.3
Jerky movement
20.4
EE
Restriction
14.3
Jerky movement
20.6
RE
Right
Ocular motility
Jerky movement
75.6 7.9
Jerky movement EE
Restriction
RE
Right
74.2 9.3
Jerky movement Visual field loss (%)
Jerky movement
75.8 7.8
Left
18.8
LE
Right
14.1
Left
20.3
EE
Right
16.9
Left
27.7
Left LE EE
16.3
6.1 4.1
Right
14.3
Left
12.2
Right
24.6
Left
16.3
RE: right eye, LE: left eye, BE: better eye, EE: either eye, VA: visual acuity.
Table 4. Prevalence of visual deficits, visual acuity, intra-ocular pressure, ocular motility and visual field restriction
Sub-score in FIM-motor HKW
KC
Mann-Whitney test
Overall
Self care
34.04 ± 9.49
29.15 ± 8.41
z = -3.146*
31.54 ± 9.24
Sphincter control
11.82 ± 3.49
10.17 ± 3.49
z = -2.021*
10.98 ± 3.57
Mobility
16.51 ± 5.50
11.87 ± 4.53
z = -4.363**
14.14 ± 5.52
9.49 ± 4.44
7.51 ± 6.71
z = -3.123*
8.48 ± 5.77
71.87 ± 20.61
55.60 ± 17.54
z = -3.953**
64.01 ± 20.76
Locomotion Motor session
Sub-score in FIM-cognition HKW
KC
Mann-Whitney test
Overall
Cognition session
30.00 ± 5.83
30.04 ± 3.88
z = -0.696
30.02 ± 4.91
Total score for FIM
101.40 ± 23.22
85.83 ± 19.60
z = -3.748**
93.53 ± 22.74
*Represents p < 0.05, ** represents p < 0.001 FIM: functional independent measures
Table 5. Performance in functional independent measures in motor and cognition sessions. Values show mean ± standard deviation
nature of the stroke clinic, where KC was the in-patient clinic and it accommodated patients with recent stroke (revealed by the shorter onset time of primary stroke, Table 2) and requirement of a greater number of drugs for general health issues (Table 1B).
Despite a relatively small sample in this study, our participants represented a good sampling of the post-stroke population in Hong Kong because the aetiology of stroke subtypes in our study was similar to a recent study, which investigated the trend of stroke incidences in Hong Kong.32 Results from
Clinical and Experimental Optometry 97.5 September 2014
438
both studies revealed that the major cause of stroke was ischaemia, followed by infarction. In terms of the locations of stroke or affected areas, the most commonly affected areas in our sample were frontal lobe (20 per cent), external and internal capsule (20 per cent) and thalamus, basal ganglia and lacunar areas (34 per cent). Damage in these areas results in different levels of functional impairment, including vision-related deficits.8,9,11 For example, the centre for controlling eye movement- in pre-motor and motor areas and the centre for vergence are located near the frontal lobe.36 Hence, a deficiency in the frontal lobe might lead to difficulty in controlling saccadic eye movements and poor vergence in binocular vision, resulting in jerky movements in ocular motility, restriction in ocular movements and poor convergence. Damage to the thalamus, basal ganglia and lacunar areas might be associated with oculomotor deficits because they are responsible for transferring information from sensory organs to the cerebral cortex via interneurones and the centre of connection in ascending and descending pathways.37 Thus, a significantly lower functional independent measures total score was identified in participants with deficit in eye movements, rather than the visual field. © 2014 The Authors
Clinical and Experimental Optometry © 2014 Optometrists Association Australia
Visual problems among stroke survivors Siong, Woo, Chan, Chung, Li, Cheung, Lai and Cheong
140 p
