Purpose We report the development of a patient-derived, health related quality of life (HRQOL) questionnaire for adults with strabismus. Design Cross-sectional study. Participants 29 patients with strabismus in a first phase, and 32 patients with strabismus, 18 patients with other eye diseases, and 13 visually normal adults in a second phase. Methods Individual patient interviews generated 181 questionnaire items. For item reduction, we asked 29 patients with strabismus to complete the 181-item questionnaire, analyzed responses, and performed factor analysis. Two prominent factors were identified, and the 10 items with the highest correlation with each factor were selected. The final 20-item questionnaire (10 ‘psychosocial’ items, 10 ‘function’ items) was administered to an additional 32 patients with strabismus (22 with diplopia, 10 without diplopia), 13 visually normal adults, and 18 patients with other eye diseases. A 5-point Likert-type scale was used for responses (‘never’=100, ‘rarely’=75, ‘sometimes’=50, ‘often’=25, and ‘always’=0). Median overall questionnaire scores and psychosocial and function sub-scale scores, ranging from 0 (worst HRQOL) to 100 (best HRQOL), were compared across groups. Main Outcome Measures HRQOL questionnaire response scores. Results Median overall scores were statistically significantly lower (worse quality of life) for patients with strabismus (56) compared to visually normal adults (95; P<0.001) and patients with other eye diseases (86; P<0.001). Median scores on the psychosocial sub-scale were significantly lower for strabismus patients (69) compared to visually normal adults (99; P<0.001) and patients with other eye diseases (94; P<0.001). For the function sub-scale, median scores were again significantly lower for strabismus patients (43) compared to visually normal adults (91; P<0.001) and patients with other eye diseases (78; P<0.001). Conclusions We have developed a 20-item, patient-derived HRQOL questionnaire specific for adults with strabismus, with sub-scales to assess psychosocial and function concerns. This 20-item, condition specific questionnaire will be useful for assessing HRQOL in individual strabismus patients and also as an outcome measure for clinical trials.

Purpose To establish the thresholds for “real change” in stereoacuity by defining long term test-retest variability as 95% limits of agreement for four stereoacuity tests. Design Retrospective cohort study. Participants and/or Controls We identified 36 patients (median age 17 years, range 7 to 76 years) with any type of stable strabismus who had stereoacuity measured on two consecutive visits. Stable strabismus was defined as angle of deviation within 5 prism diopters (pd) by simultaneous prism and cover test (SPCT) and prism and alternating cover test (PACT). Methods Stereoacuity was measured at near using the Preschool Randot and the near Frisby stereotests and at distance using the Frisby Davis Distance (FD2) and the Distance Randot stereotests. Stereoacuity was transformed to log units for analysis. 95% limits of agreement were calculated based on a 1.96 multiple of the standard deviation of differences between test and retest. Main Outcome Measures 95% limits of agreement for change in stereoacuity thresholds at two consecutive visits. Results 95% limits of agreement were 0.59 log arcsec for the Preschool Randot, 0.24 for the near Frisby, 0.68 for the FD2, and 0.46 for the Distance Randot. These values correspond to the following octave steps (doublings of threshold; for example, 200 to 400 arcsec): Preschool Randot 1.95, near Frisby 0.78, FD2 2.27, and Distance Randot 1.52. Conclusions A change of approximately two octaves of stereoacuity threshold are needed to exceed test-retest variability for most stereoacuity tests. Changes less than two octaves cannot be distinguished from test-retest variability. When used to guide patient management, caution should be taken in interpreting changes in stereoacuity of less than two octaves.

Purpose We report the development and initial validation of patient–derived, health related quality of life (HRQOL) questionnaires for intermittent exotropia (IXT). Design Cross-sectional study Participants In a development phase, 27 children (aged 2–17 years) with IXT and one of their parents. In an initial validation phase, 33 children with IXT and 49 control children (aged 5–17 years) along with one parent for each child. Children in the control group had no strabismus or amblyopia. Methods Individual patient interviews generated 35 items for Child and Proxy (parental assessment of child’s HRQOL) questionnaires and 46 items for a Parent questionnaire. To reduce to a feasible number of items, questionnaires were administered to 5–17 year old children with IXT (n=15) and parents of 2–17 year old children with IXT (n=27). Responses were analyzed using standard item reduction methodology. Three final derived IXT questionnaires (IXTQ): Child, Proxy, and Parent (12, 12, and 17 items respectively) were administered to children with IXT and control children, and to parents of IXT and control children. Likert-type scales ranging from ‘never’ (score 100, best HRQOL) to ‘almost always’ (score 0, worst HRQOL) were used for responses. Main outcome measures Median scores for IXT and control groups, compared using Wilcoxon tests. Results Median Child scores were significantly lower (worse HRQOL) in the IXT group compared with the control group: 85 (quartiles 73–92) versus 92 (79–96); P=0.04. Median Proxy IXTQ scores were significantly lower for IXT children than controls: 83 (75–94) versus 98 (92–100); P<0.0001. Median Parent IXTQ scores were also significantly lower in the IXT group compared with the control group: 68 (quartiles 56–79) versus 93 (87–99); P<0.0001. Conclusions We have developed and validated a new 3-part patient-derived HRQOL questionnaire for children with IXT and their parents, comprising Child, Proxy and Parent questionnaires. These questionnaires detect reduced HRQOL in children with IXT as reported by the child themselves and as perceived by their parents (proxy report). Childhood IXT also appears to affect the HRQOL of the parents. The IXTQ HRQOL questionnaires may prove useful in the clinical assessment of IXT and for clinical trials.

The AS-20 benefits from reduction to 4 subscales (self-perception, interaction, reading function, and general function) and reducing the response options in the general function subscale from 5 to 4 options. The refined AS-20 may prove to be even more responsive to HRQOL changes in adult strabismus following treatment or changes over time.

Purpose: As a first step in the development of a health related quality of life instrument, we conducted in-depth interviews to identify the specific concerns of adults with strabismus. Design: Prospective cross-sectional studyMethods: Thirty adults with strabismus, 17 with diplopia and 13 without were recruited. Individual interviews, using 11 open-ended questions, were audiotaped, transcribed and transcripts reviewed independently by 3 investigators. Phrases regarding how strabismus affected everyday life were grouped into topic areas and the frequency of each topic analyzed for subjects with and without diplopia.

Purpose To report changes in health-related quality of life (HRQOL) 1 year following strabismus surgery. Design Retrospective cohort study Methods 73 adults undergoing strabismus surgery in a single clinical practice completed the Adult Strabismus-20 (AS-20) HRQOL questionnaire pre-operatively and at 6 weeks and 1 year post-operatively. All included adults were successfully aligned at 6 weeks post-operatively. Success was defined based on clinical criteria. Change in AS-20 psychosocial and function scores was evaluated as: 1) difference in scores between 6 weeks and 1 year post-operatively and 2) proportions exceeding previously published limits of agreement at 6 weeks and 1 year. Results For patients successfully aligned at both 6 weeks and 1 year (n=51), further improvement in median scores was seen from 6 weeks to 1 year for both the psychosocial scale (83.8 vs 93.8; P<0.0001) and the function scale (72.5 vs 77.5; P=0.007). Also, a greater proportion exceeded limits of agreement at 1 year than at 6 weeks (psychosocial: 48% vs 30%; P=0.007, function: 67% vs 51%; P=0.01). For patients who became partial success (n=18) or failure (n=4) at 1 year there was a numerical decrease in scores at 1 year. Conclusions Adult strabismus patients who remain successfully aligned, show continued improvement in both psychosocial and function scores from 6 weeks to 1 year post-operatively, indicating that improvement in HRQOL is long-lasting. Evaluation of HRQOL should be considered when reporting strabismus surgery outcomes in clinical trials, and may prove helpful in assessing outcomes in clinical practice.

Objective To evaluate the responsiveness of 2 health related quality of life (HRQOL) questionnaires, the Adult Strabismus-20 (AS-20) and National Eye Institute Visual Function Questionnaire-25 (VFQ-25), to changes in HRQOL following strabismus surgery. Design Cohort study Participants 106 adults (aged 18 to 84, median 48.5 years) undergoing strabismus surgery, 80 (75%) with diplopia and 26 (25%) without diplopia. Methods All participants completed AS-20 and VFQ-25 questionnaires pre-operatively and a median of 7 (range 4 to 13) weeks post-operatively. Using pre-defined clinical criteria, post-operative outcomes were graded as either ‘success’ (n=65), ‘partial success’ (n=32) or ‘failure’ (n=9). Main outcome measures For each questionnaire, mean composite and subscale scores (ranging from 0 to 100; worst to best HRQOL) were calculated for each patient. Median change in scores pre- to post-operatively was compared for successes, partial successes, and failures, and the proportion of patients whose scores exceeded 95% limits of agreement was calculated. Results Successfully aligned diplopic patients (n=46) showed greater improvement than failures (n=7) using both the AS-20 questionnaire (21.3 [quartiles 12.5 to 35.0] vs. 8.8 [3.8 to 12.5]; P=0.002) and the VFQ-25 questionnaire (18.3 [8.6 to 26.1] vs. 8.3 [0.8 to 13.5]; P=0.02). Successfully aligned non-diplopic patients (n=19) also showed greater improvement than failures (n=2): (AS-20 23.8 [10.0 to 32.5] vs. −3.1 [−10.0 to 3.8]; P=0.05). In non-diplopic patients, changes on VFQ-25 were small but significantly greater for successes than failures (5.0 [0.0 to 10.1] vs. −15.4 [−19.4 to −11.4]; P=0.03). More successfully aligned patients showed improvement exceeding the 95% limits of agreement for AS-20 scores than VFQ-25 scores (67% vs. 65% [P=0.8] for diplopic patients and 63% vs. 21% [P=0.005] for non-diplopic patients). Conclusions AS-20 and VFQ-25 questionnaires are responsive to improved HRQOL in adults undergoing successful strabismus surgery. Changes on VFQ-25 were smaller, particularly for non-diplopic strabismus. The AS-20 is more responsive than the VFQ-25 across the range of adult strabismus.

Purpose Bangerter filters are designed to cause progressive degradation of distance optotype acuity to predicted levels (density label indicating expected decimal acuity) and are used to treat amblyopia and diplopia. Nevertheless, there are few data reporting induced acuity deficits. We investigated the effect of Bangerter filters on distance and near optotype acuity, vernier acuity, and contrast sensitivity. Methods Fifteen subjects with best corrected optotype acuity of at least 20/25 in each eye were blurred sequentially in one eye with 7 Bangerter filters (densities <0.1, 0.1, 0.2, 0.3, 0.4, 0.8, 1.0). At each filter level distance and near optotype acuity (LogMAR), vernier acuity and contrast sensitivity were assessed. Mean log acuities were compared using generalized estimating equation methods. Results The 1.0, 0.8, and 0.4 filters degraded distance optotype acuity to a similar degree (mean 0.22, 0.23, and 0.28 logMAR). Subsequent filters progressively degraded acuity: 0.44, 0.57, 0.93, 1.69 logMAR. Near optotype acuity was reduced in a similar pattern. Vernier acuity was minimally degraded by 1.0, 0.8, and 0.4 filters (18, 19, and 20 arcsec), followed by progressive degradation with subsequent filters (31, 35, 113, and 387 arcsec). Contrast sensitivity was minimally reduced with filters 1.0 through 0.2, and then precipitously degraded with 0.1 and <0.1 filters. Conclusion The 1.0, 0.8, and 0.4 filters cause similar, minimal degradation of distance and near optotype, and vernier acuity, whereas subsequent filters cause progressive degradation. Contrast sensitivity is not markedly reduced until the 0.1 filter. These results have important implications for using Bangerter filters therapeutically.