To assess relative quality of life in patients with strabismus.
Retrospective cohort study.
The 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) was performed in 42 strabismic adults over the age of 50 years at a single institution. Subscale scores were compared with those of patients with other ocular diseases, including diabetic retinopathy, age-related macular degeneration (AMD), glaucoma, cataract, cytomegalovirus (CMV) retinitis, and low vision.
Median visual acuity was 20/20 (range 20/12.5–20/50), and 34 patients (81%) reported diplopia. Strabismic patients performed the same or worse on nearly all vision-related subscales than did patients with diabetic retinopathy, age-related macular degeneration, glaucoma, cataract, and CMV retinitis. Additionally, strabismic patients reported significantly worse ocular pain than all comparison groups before any surgery was performed.
Strabismus impacts quality of life through both functional and psychosocial factors. Physicians treating strabismic patients should recognize these quality-of-life issues and address them accordingly.
Strabismus affects approximately 4% of the adult population and can have functional effects. In addition to being troubled by diplopia, patients may be troubled by the abnormal facial appearance of strabismus. Additionally, patients with strabismus are more likely to have mental health problems, including high rates of depressive symptoms and social phobia.
Little is known about how quality of life in strabismic patients compares to that in patients with other ocular diseases. One study reported that patients who underwent surgery for incomitant strabismus reported greater improvement in quality of life using the Visual Function Questionnaire-14 than did patients who had surgery for diabetic macular edema, comitant strabismus, glaucoma with cataract, and glaucoma alone. The improvement in quality of life for patients with incomitant strabismus who underwent surgery was similar to patients who had cataract surgery. However, to date there has been no comparison of quality of life in strabismus to other ocular diseases that includes both surgical and nonsurgical patients.
The 25-item National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) is a reliable and valid scale that captures the influence of vision on multiple dimensions of quality of life, including emotional well-being and social functioning. The NEI VFQ-25 subscale scores of patients with diabetic retinopathy, age-related macular degeneration (AMD), glaucoma, cataract, cytomegalovirus (CMV) retinitis, and low vision have been reported previously. By comparing the NEI VFQ-25 scores in strabismic patients to these patients, this study aimed to demonstrate the relative impact of strabismus on quality of life.
This retrospective study was approved by the University of California, Los Angeles Institutional Review Board and conformed to the requirements of the US Health Insurance Portability and Accountability Act. Written informed consent was obtained from the participants. Strabismic patients were recruited during 2010 through 2012 from the clinics of 4 strabismologists (S.L.P., J.L.D., F.G.V., and S.J.I.) during preoperative visits. Only patients over the age of 50 were included in this study between September 2011 and June 2014, to permit a closer comparison to the NEI VFQ-25 Field Test groups.
Since these quality-of-life surveys were part of a larger study with preexisting exclusion criteria, patients with any known history of treatment for amblyopia, dissociated vertical or dissociated horizontal deviation as the sole form of strabismus, pathologic nystagmus, or neurologic diseases were excluded.
Demographic and Clinical Data
The following demographic and clinical data were collected: age, sex, ethnicity, type of strabismus, other ocular diseases, and presence or absence of diplopia. Visual acuity and stereoacuity were measured as described below.
Participants underwent visual acuity examination using the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol with their habitual refractive correction. If visual acuity was worse than 0.20 logMAR in either eye, manifest refraction was performed and the study tests were performed with this refraction.
Binocular visual acuity was tested using the Precision Vision 3 meter ETDRS chart and the ETDRS protocol. The visual acuity score was calculated as the total number of correct letters plus 30 letters. The maximum score of 100 letters corresponded to a Snellen visual acuity of 20/10. Visual acuity was converted to Snellen acuity using the ETDRS chart to facilitate comparison with NEI VFQ-25 Field Test groups.
Near stereoacuity was evaluated using the Titmus Near Stereo Test (Stereo Optical Co, Chicago, Illinois, USA). Distance stereoacuity was measured using the Distance Randot Stereotest (Stereo Optical Co).
NEI VFQ-25 Scoring
NEI VFQ-25 interviews were conducted by trained technicians. Using the NEI VFQ-25 scoring algorithm, the patients’ answers were converted to a 100-point scale, with 100 being the optimum score and 0 being the worst score. The scores were averaged to generate 12 subscale scores: General Health, General Vision, Ocular Pain, Near Activities, Distance Activities, Vision-Specific Social Functioning, Vision-Specific Mental Health, Vision-Specific Role Difficulties, Vision-Specific Dependency, Driving, Color Vision, and Peripheral Vision. Means and standard deviations of the subscale scores for the patients with strabismus were calculated.
Comparison of NEI VFQ-25 Scores
Comparisons were made to published NEI VFQ-25 subscale scores for diabetic retinopathy, age-related macular degeneration, glaucoma, cataract, CMV retinitis, and low vision. Differences were calculated using a 2-sample t test, with a P value of .05 or less considered significant. Since a total of 72 comparisons were performed, the Bonferroni correction was applied, and the corrected threshold for significance was determined to be .0007.
Forty-two patients over the age of 50 with strabismus participated in the study. Demographic and clinical features of these patients are shown in Table 1 . Mean age was 65 years (range 52–90 years). Twenty-two patients (54%) were female. Median binocular visual acuity was 20/20 (range 20/12.5–20/50). Ethnicity was reported as white in 36 patients, Asian in 3 patients, and Hispanic in 3 patients.
|Mean age, y (range)||65 (52–90)|
|Female (%)||22 (54%)|
|Median binocular visual acuity (range)||20/20 (20/12.5–20/50)|
|Hispanic or Latino||3|
|Type of strabismus|
|Combined vertical and horizontal strabismus||4|
|Other ocular disease|
|Number (%) of patients with measurable near stereoacuity||15 (36%)|
|Number (%) of patients with measurable distance stereoacuity||9 (21%)|
|Number (%) of patients with diplopia||34 (81%)|
Types of strabismus included 15 patients with esotropia, 8 patients with exotropia, 15 patients with hypertropia, and 4 patients with combined vertical and horizontal deviations. Diplopia was reported by 34 patients (81%). Fifteen patients (36%) had measurable stereoacuity at near, and 9 patients (21%) had measurable stereoacuity at distance.
Table 2 compares age, sex, and binocular visual acuity between the strabismic patients and the comparison groups. Age was significantly different between the strabismic patients and all other groups, except glaucoma patients ( P = .29) and low vision patients ( P = .17). Patients with diabetic retinopathy and CMV retinitis were younger than strabismic patients, whereas patients with age-related macular degeneration and cataracts were older than strabismic patients. The sex distribution was not significantly different between strabismic patients and the other groups, except CMV retinitis, in which nearly all patients were male ( P < .0001). Median binocular visual acuity was 20/20 in the strabismic patients, which was the same as CMV retinitis patients, and within 3 lines of the diabetic retinopathy, glaucoma, and cataract groups. Median binocular visual acuity was 20/63 in age-related macular degeneration patients, 6 lines worse than the strabismic patients.
|Strabismus (N = 42)||Diabetic Retinopathy (N = 123)||AMD (N = 108)||Glaucoma (N = 77)||Cataract (N = 93)||CMV Retinitits (N = 37)||Low Vision (N = 90)|
|Mean age ± SD, y||65 ± 9||57 ± 12 |
P < .0001
|76 ± 10 |
P < .0001
|67 ± 11 |
P = .29
|73 ± 9 |
P < .0001
|39 ± 7 |
P < .0001
|68 ± 16 |
P = .17
|Female, n (%)||22 (54%)||81 (66%) |
P = .12
|68 (63%) |
P = .23
|42 (54%) |
P = .82
|61 (66%) |
P = .14
|2 (5%) |
P < .0001
|61 (68%) |
P = .08
|Median binocular visual acuity||20/20||20/40||20/63||20/25||20/40||20/20||20/252|
The NEI VFQ-25 subscale scores for strabismic patients and comparison groups are shown in Table 3 . Statistically significant differences between strabismic patients and other groups at a threshold of .0007 (calculated using the Bonferroni correction) are indicated by the shading of cells in the table. Cells shaded dark gray indicate subscale scores that were significantly better than strabismic patients, light gray cells denote subscale scores that were not significantly different from strabismic patients, and white cells indicate subscale scores that were significantly worse than strabismic patients. The Supplemental Table (available at AJO.com ) shows the same comparisons with the P value for significance set to .05. With the exception of the General Health subscale, nearly all subscale scores were significantly worse or not significantly different in strabismic patients compared to patients with diabetic retinopathy, age-related macular degeneration, glaucoma, cataract, and CMV retinitis. The subscale scores that were significantly better in strabismic patients were Driving and Color Vision compared to age-related macular degeneration patients. Additionally, subscale scores were significantly better or not significantly different in patients with strabismus compared to low vision patients, except for the Ocular Pain subscale. Strabismic patients reported significantly worse ocular pain than patients in all other groups.
|Strabismus (N = 41)||Diabetic Retinopathy (N = 123)||AMD (N = 108)||Glaucoma (N = 77)||Cataract (N = 93)||CMV Retinitis (N = 37)||Low Vision (N = 90)|
|General health||68 ± 22||46 ± 25||65 ± 25||62 ± 25||55 ± 25||45 ± 24||57 ± 27|
|General vision||59 ± 20||62 ± 21||53 ± 20||71 ± 17||60 ± 17||76 ± 14||38 ± 18|
|Ocular pain||65 ± 26||88 ± 17||87 ± 17||89 ± 14||86 ± 19||90 ± 16||85 ± 20|
|Near activities||61 ± 20||63 ± 30||54 ± 27||79 ± 23||73 ± 21||84 ± 20||36 ± 23|
|Distance activities||67 ± 21||66 ± 30||56 ± 29||77 ± 25||73 ± 22||84 ± 18||38 ± 26|
|VS social functioning||81 ± 22||81 ± 26||73 ± 29||89 ± 20||87 ± 19||96 ± 9||50 ± 31|
|VS mental health||53 ± 28||66 ± 29||58 ± 27||81 ± 20||77 ± 22||74 ± 22||46 ± 27|
|VS role difficulties||56 ± 29||69 ± 31||61 ± 31||84 ± 23||76 ± 22||78 ± 24||44 ± 29|
|VS dependency||82 ± 22||77 ± 30||72 ± 30||92 ± 19||88 ± 20||89 ± 12||51 ± 31|
|Driving||67 ± 23||55 ± 40||39 ± 36||75 ± 28||63 ± 30||80 ± 28||10 ± 23|
|Color vision||94 ± 13||90 ± 22||85 ± 25||93 ± 17||90 ± 20||98 ± 9||71 ± 31|
|Peripheral vision||68 ± 25||78 ± 29||77 ± 27||76 ± 27||87 ± 21||78 ± 21||59 ± 32|
Nine strabismic patients also had other ocular disorders, including cataract (n = 3), glaucoma (n = 1), age-related macular degeneration (n = 1), dry eye (n = 1), high myopia (n = 1), retinal detachment (n = 1), and blepharoptosis (n = 1). A separate analysis excluding strabismic patients with these confounding ocular diseases found no change in the direction of difference between subscale scores of strabismic patients and the comparison groups.