Purpose
Many clinicians treat unilateral amblyopia with glasses alone and initiate patching when needed; others start glasses and patching simultaneously. In this study, we reviewed the outcomes of the two approaches at our institution.
Design
Retrospective nonrandomized clinical trial.
Methods
Setting: Institutional practice. Patient population: All patients diagnosed with amblyopia at Boston Children’s Hospital between 2010 and 2014. Inclusion criteria : Unilateral amblyopia (visual acuity (VA) 20/40 to 20/200 with interocular difference ≥3 lines,) age 3 to 12 years, with a 6-month follow-up visit. Exclusion criteria : Deprivation amblyopia, prior amblyopia treatment, treatment other than patching, surgery. Patients were categorized as “simultaneous treatment” (concurrent glasses and patching therapy at their first visit) or “sequential treatment” (glasses alone at first visit, followed by patching therapy at second visit.) Observation procedures : Patient demographics, VA, and stereopsis were compared. Outcome measures : VA and stereopsis at the last visit on treatment.
Results
We identified 98 patients who met inclusion criteria: 36 received simultaneous treatment and 62 sequential treatment. Median amblyopic eye VA improved similarly between the simultaneous (∆0.40; interquartile range [IQR], 0.56-0.30 logMAR) and sequential (∆0.40; IQR, 0.52-0.27 logMAR) groups. Patients without stereopsis at first visit had better stereopsis outcomes with sequential treatment (5.12 [IQR, 4.00-7.51] log stereopsis) compared with simultaneous treatment (8.01 [IQR, 5.65-9.21]) log stereopsis, P = 0.046).
Conclusions
VA improved approximately 4 lines regardless of treatment type. For children without stereopsis at first presentation, sequential patching yielded better stereopsis outcomes. These findings require further validation and highlight the importance of evaluating stereopsis in future studies.
A mblyopia is a major cause of vision impairment in children, with an estimated prevalence of 1% to 5%. The American Academy of Ophthalmology’s Preferred Practice Pattern recommends treating amblyopia with glasses only as a first step, followed by part-time occlusion of the nonamblyopic fellow-eye if glasses alone are not effective (“sequential treatment”). This sequential addition of part-time occlusion therapy, when required, works to further improve vision. However, approximately half of children treated with sequential therapy do not regain normal visual acuity (VA). A proposed alternative to sequential treatment is the concurrent initiation of full-time glasses wear and part-time occlusion therapy (“simultaneous treatment”).
Whether sequential or simultaneous amblyopia therapy is the superior approach is controversial. Advocates of the sequential treatment strategy argue that it avoids part-time occlusion therapy entirely when glasses alone are successful and may help ease families into patching for children who have residual amblyopia after treatment with spectacles alone. Supporters of simultaneous therapy argue that it allows patients to start part-time occlusion at a younger age, shortens the course of treatment, and improves VA more rapidly. Our group previously evaluated outcomes of sequential vs simultaneous treatment in patients with bilateral amblyopia, but we are aware of no such published studies in unilateral amblyopia. In this study, we used our large retrospective amblyopia database of more than 2000 patients to evaluate whether either of these treatment strategies produced better amblyopia treatment outcomes in both VA and stereopsis.
PATIENTS AND METHODS
This study was a retrospective, longitudinal cross-sectional data set analysis at Boston Children’s Hospital, Boston, Massachusetts. The study adhered to the tenets of the Declaration of Helsinki, was approved by the Boston Children’s Hospital Institutional Review Board, and was compliant with the United States Health Information Portability and Accountability Act.
A database of all patients billed for amblyopia (International Classification of Diseases, 9th Edition, code 368.XX) between 2010 and 2014 was created as the basis of what we refer to as the Boston Amblyopia Study. Details of this study are provided by Shoshany and associates. Briefly, best-corrected VA (BCVA) measures were obtained using Snellen, HOTV, or LEA optotypes (linear, crowding bars, or single letters) based on the patient’s age and literacy. Stereopsis measures were obtained at near using the Titmus fly, Randot animals and circles, the Frisby Near Stereo Test, or the Lang I Stereo card, based on the patients’ ability. The highest level of stereopsis achieved was recorded, regardless of the test performed. In our practice, stereopsis is normally tested with current correction; however, the use of correction during stereopsis testing was not consistently recorded.
For the present study, inclusion criteria included age 3 to <13 years at the time of the first record entry with unilateral amblyopia (interocular difference [IOD] ≥3 logMAR lines, VA 20/40 to 20/200 in the amblyopic eye, and VA 20/40 or better in fellow eye , ) with a visit at 6 ± 3 months. Exclusion criteria included previous amblyopia treatment, treatment with atropine or other nonpatching forms of amblyopia therapy, deprivation amblyopia, strabismus or cataract surgery, patients who were lost to follow-up (patients who took greater than two times the recommended follow-up time to return for their next visit) for return visits, and ocular or neurodevelopmental comorbidities.
Amblyopia subtypes were defined as “anisometropic,” ≥1.00-diopter (D) difference between eyes in spherical equivalent or ≥1.50-D difference in astigmatism between corresponding meridians in the two eyes; “strabismic,” presence of a heterotropia on examination at distance or near fixation (with or without optical correction); or “mixed,” met criteria for strabismic and anisometropic amblyopia. Amblyopia severity was categorized as “moderate” (20/40-20/80 BCVA of the amblyopic eye) and “severe” (>20/80 BCVA of the amblyopic eye). , Patients were grouped into age cohorts by their age at the first visit: “younger” (3-6 years) and “older” (7-12 years).
Records of patients meeting inclusion criteria were selected if their amblyopia treatment history matched one of the two regimens: (1) “simultaneous treatment,” combined initiation and maintenance of full-time glasses wear and part-time patching of the nonamblyopic fellow eye at the patient’s first visit; (2) “sequential treatment,” initiation and maintenance of full-time glasses wear at the patient’s first visit, followed by the subsequent addition of part-time patching of the fellow eye at the second visit of the patient record in conjunction with full-time glasses wear.
Treatment regimens persisted as long as full-time spectacle wear and part-time patching of the fellow eye were maintained by the managing clinician. Treatment regimens were terminated, marking the last visit on treatment, when part-time patching of the fellow eye was discontinued or with the start or replacement of another form of amblyopia therapy (eg, atropine penalization).
Self-reported compliance data were available for all patients. The main outcome measure was amblyopic eye VA and stereopsis at the last treatment visit. Improvements were measured at the 6-month visit and at the last visit on treatment.
For statistical analysis, details are provided by Shoshany and associates. Briefly, demographics and patient characteristics are presented as frequency and percentage for categorical data and median and interquartile range for continuous data. Visual measures (VA and IOD) and stereopsis data are presented as median and interquartile range and were analyzed using nonparametric methods. Comparisons between the simultaneous and sequential treatment group included the χ 2 test, Fisher exact test, or the Wilcoxon rank sum test, as appropriate.
Longitudinal visual measures and stereopsis data were analyzed nonparametrically using the Wilcoxon signed ranks test to compare the first visit, 6-month visit, and last visit on treatment to account for repeated measurements within patients. Multiple variables were evaluated for correlation with visual measures and stereopsis improvement at the last treatment visit to determine whether there were any confounding effects on treatment outcomes, including age at the first visit (younger cohort vs older cohort), sex, family history of amblyopia, amblyopia subgroup (anisometropic vs strabismic vs mixed), amblyopia severity (moderate vs severe), and initial level of stereopsis (identification of the Titmus fly). To adjust for baseline factors that reached significance on univariate comparison of the two groups, multivariable median regression analysis was performed. Results from median regression are reported as adjusted coefficients with corresponding 95% CI and P value. All statistical analyses were performed using Stata 16.0 software (StataCorp LLC). A two-tailed α level of 0.05 was used to determine statistical significance, and a two-tailed Bonferroni-adjusted P < .017 was applied to account for multiple comparisons in longitudinal analyses.
LITERATURE REVIEW
PubMed was used to perform a literature search on January 4, 2021. There were no restrictions on year published. Search terms included “amblyopia” and “stereopsis.” We reviewed all citations for reports of sequential vs simultaneous patching in articles identified by the literature search. Foreign literature for which an abstract was available in English was reviewed.
RESULTS
Of the 2311 patients in the Boston Amblyopia Study database, 474 met criteria for unilateral amblyopia based on our defined criteria. Of these, 98 met all inclusion and exclusion criteria for the present study ( Figure 1 ), including 36 in the simultaneous treatment group and 62 in the sequential treatment group. The simultaneous group was composed of significantly more patients in the older cohort compared with the sequential group ( P ≤ .04); however, median age was not significantly different between age-groups (simultaneous: 5.26 years old vs sequential: 5.1 years old; P ≥ .238) ( Table 1 ). The groups did not differ significantly in presenting sex, race or ethnicity, insurance status, family history of amblyopia, mechanism of amblyopia, severity of amblyopia, prescribing trends, length of treatment, number of visits on treatment, glasses or patching compliance, treatment termination, first visit VA in the amblyopic eye, IOD, and log stereopsis ( Tables 1 and 2 ).
| Variable | Simultaneous Treatment | Sequential Treatment | P Value |
|---|---|---|---|
| (n = 36) | (n = 62) | ||
| Age, y | 5.26 (4.23, 7.11) | 5.10 (4.11, 5.62) | .238 |
| Age of cohort, y | .040 a | ||
| Younger cohort (3 to < 7) | 26 (72.2) | 56 (90.3) | |
| Older cohort (7 to <13) | 10 (27.8) | 6 (9.7) | |
| Sex | .441 | ||
| Female | 17 (47.2) | 23 (37.1) | |
| Male | 19 (52.8) | 39 (62.9) | |
| Race | .301 | ||
| White | 21 (58.3) | 39 (62.9) | |
| Black or African American | 0 (0) | 3 (4.8) | |
| Asian | 2 (5.6) | 4 (6.5) | |
| Other | 6 (16.7) | 3 (4.8) | |
| Unknown or declined/unable to answer | 7 (19.4) | 13 (21.0) | |
| Ethnicity | .395 | ||
| Hispanic or Latino | 4 (11.1) | 3 (4.8) | |
| Not Hispanic or Latino | 26 (72.2) | 41 (66.1) | |
| Unknown or declined/unable to answer | 6 (16.7) | 18 (29.1) | |
| Insurance payer | .295 | ||
| Private | 9 (25.0) | 21 (33.9) | |
| Public | 26 (72.2) | 41 (66.1) | |
| International or self-payer | 1 (2.8) | 0 (0) | |
| Family history of amblyopia | 9 (25.0) | 15 (24.2) | .999 |
| Type of amblyopia b | .286 | ||
| Anisometropic | 23 (63.9) | 34 (54.8) | |
| Strabismic | 6 (16.7) | 7 (11.3) | |
| Mixed | 7 (19.4) | 21 (33.9) | |
| Amblyopia severity | .816 | ||
| Moderate: 20/40 to ≤20/80 BCVA | 21 (58.3) | 39 (62.9) | |
| Severe: >20/80 and ≤20/200 BCVA | 15 (41.7) | 23 (37.1) | |
| Level of stereopsis | .615 | ||
| <3000 arcsec | 11 (30.5) | 22 (35.5) | |
| ≥3000 arcsec | 25 (69.5) | 40 (64.5) | |
| Prescribing trends | .936 | ||
| Department average, % | 50 (9, 91) | 50 (13, 88) | |
| Treatment compliance | |||
| Average glasses wear, % | 100 (68.2, 100) | 100 (87.5, 100) | .264 |
| Average patching prescribed, h/wk | 14 (13.2, 23.8) | 14 (13.3, 19.3) | .773 |
| Average patching compliance, h/wk | 11.5 (8.7, 14) | 11.5 (4.5, 15.5) | .796 |
| Average patching compliance, % | 77.0 (62.8, 100) | 78.6 (35.7, 100) | .388 |
| Treatment information | |||
| Time from first to 6-month visit, y | 0.49 (0.38, 0.58) | 0.50 (0.41, 0.55) | .805 |
| Time from first to last visit, y | 1.31 (1.01, 3.08) | 1.42 (1.02, 2.45) | .944 |
| Visits to 6-month visit, No. | 3 (2, 3) | 3 (2, 3) | .368 |
| Visits to last visit, No. | 5 (4, 7) | 6 (4, 7) | .499 |
| Treatment ended disposition | .742 | ||
| Discontinued by physician | 28 (77.8) | 45 (72.6) | |
| Ended to switch to atropine treatment | 8 (22.2) | 17 (27.4) |
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