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Prism under cover test in alternate fixation horizontal strabismus
Jaime Tejedor1,2, Francisco José Gutiérrez-Carmona1
1a Department of Ophthalmology , Hospital Ramón y Cajal , Madrid , Spain.
Insights
The prism under cover test (PUCT) effectively quantifies manifest deviation in children with horizontal strabismus when the simultaneous prism and cover test (SPCT) is not feasible. This method offers good repeatability and supports monofixation syndrome diagnosis.
Area of Science:
- Ophthalmology
- Pediatric Ophthalmology
- Strabismus Management
Background:
- Assessing manifest deviation in pediatric horizontal strabismus is crucial for diagnosis and management.
- The simultaneous prism and cover test (SPCT) is a standard method, but its feasibility can be limited in certain pediatric cases.
- The prism under cover test (PUCT) offers a potential alternative for quantifying deviations.
Purpose of the Study:
- To evaluate the clinical applicability of the prism under cover test (PUCT) for measuring manifest horizontal strabismus in children.
- To determine if PUCT can be reliably used when the simultaneous prism and cover test (SPCT) is not feasible.
- To assess the correlation of PUCT with other measures like stereoacuity and compare it with SPCT and alternate prism and cover test (APCT).
Main Methods:
- A study involving children aged 4-11 years with alternate fixation horizontal strabismus.
- Participants were divided into two groups: SPCT not feasible (n=18) and SPCT feasible (n=24).
- Measurements included refraction, PUCT, APCT, fusion, stereoacuity, and analysis of PUCT repeatability and agreement with SPCT.
Main Results:
- In the group where SPCT was not feasible, PUCT showed good repeatability (coefficient of repeatability: 3.4 PD) and a strong intraclass correlation (ICC: 0.90) with APCT.
- In the group where SPCT was feasible, PUCT demonstrated high agreement with SPCT (concordance correlation coefficient: 0.91).
- PUCT showed a better correlation with stereoacuity (0.78) compared to APCT (0.58) in the second group.
Conclusions:
- The prism under cover test (PUCT) is a repeatable procedure suitable for estimating manifest deviation in children with horizontal strabismus.
- PUCT is particularly valuable when the simultaneous prism and cover test (SPCT) cannot be performed.
- The findings support the use of PUCT in diagnosing conditions like monofixation syndrome.
Purpose:
To evaluate the applicability of the prism under cover test (PUCT) to quantify manifest deviation in horizontal strabismus with alternate fixation when simultaneous prism and cover test (SPCT) is not feasible.
Methods:
Children aged 4-11 years, with alternate fixation horizontal strabismus and alternate prism and cover test (APCT) distance deviation (DD) up to 25 PD were eligible. In group 1 of the study, SPCT was not feasible (n = 18), whereas in group 2, it was feasible (n = 24). Refraction, PUCT, APCT, central/peripheral fusion, and stereoacuity were measured. Repeatability of PUCT, agreement between PUCT and SPCT, and Pearson correlations between variables were studied.
Results:
In group 1, mean DD was 15.6 and 9.5 PD using APCT and PUCT, respectively (intraclass correlation, ICC: 0.90). Mean stereoacuity was 201.1 arc seconds. PUCT was better correlated with stereoacuity than APCT, but not significantly (p = 0.12). Coefficient of repeatability for PUCT was 3.4 PD. In group 2, mean DD was 17.6, 14.1, and 12.5 PD using APCT, PUCT, and SPCT, respectively. Mean stereoacuity was 285.9 arc seconds. Correlations APCT-PUCT (0.87), APCT-SPCT (0.82), and SPCT-PUCT (0.95) were significant. APCT did not show as good correlation with stereoacuity (0.58) as SPCT and PUCT (0.74 and 0.78, respectively). Concordance correlation coefficient between SPCT and PUCT was 0.91, and Bland Altman agreement between the two variables was also good.
Conclusions:
PUCT is a procedure with good repeatability, of interest in children to estimate manifest deviation when SPCT is not feasible, and in support of the diagnosis of monofixation syndrome.
