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A prospective study of fusional convergence parameters in Chinese patients with intermittent exotropia
Jason C S Yam1, Gabriela S L Chong, Patrick K W Wu
1Department of Ophthalmology, Tung Wah Eastern Hospital, Hong Kong. yamcheuksing@gmail.com
Insights
Fusional reserve ratio is a key indicator for controlling intermittent exotropia in children. A ratio of 2 or higher at distance suggests good control, aiding in treatment strategies.
Area of Science:
- Ophthalmology
- Pediatric Ophthalmology
- Strabismus Research
Background:
- Intermittent exotropia is a common childhood strabismus.
- Assessing the level of control is crucial for managing intermittent exotropia.
- Fusional convergence parameters are potential indicators of strabismus control.
Purpose of the Study:
- To investigate the relationship between fusional convergence measures and the Newcastle Control Score (NCS) in children with intermittent exotropia.
- To identify specific fusional convergence parameters that correlate with the degree of control in intermittent exotropia.
Main Methods:
- Prospective observational study of 101 Chinese children diagnosed with intermittent exotropia.
- Assessment of angle of deviation and fusional convergence by a single examiner.
- Evaluation of control levels using the revised Newcastle Control Score (NCS), categorizing into good, moderate, and poor control.
Main Results:
- Total convergence amplitude did not significantly differ across control groups.
- Convergence reserve was notably lower in children with poor control compared to good control groups (P < 0.001).
- Fusional reserve ratio demonstrated the strongest correlation with the NCS (near ratio: r = -0.66; distant ratio: r = -0.59; P < 0.001).
Conclusions:
- Total convergence amplitude is not a reliable indicator of control in intermittent exotropia.
- Convergence reserve is diminished in children with poorer control of intermittent exotropia.
- A fusional reserve ratio of 2 or greater at distance is a significant predictor of good control in children with intermittent exotropia.
Purpose:
To evaluate the correlation between different fusional convergence parameters and the Newcastle Control Score (NCS) in children with intermittent exotropia.
Methods:
In this consecutive prospective observational series, 101 Chinese children with intermittent exotropia were examined by a single observer, who assessed the level of control using the revised NCS and measured the angle of deviation and fusional convergence. Levels of control were defined according to the NCS as good (0-3), moderate (4-6), or poor (7-9). The correlation between the different fusional convergence parameters and the NCS was evaluated.
Results:
The total convergence amplitude was similar among the different control groups (P = 0.288 and P = 0.628 at near and at distance, respectively). The convergence reserve was higher in the good control group compared with the moderate and poor control groups, both at near (P = 0.001) and at distance (P = 0.001). Among all fusional convergence parameters, we determined that the fusional reserve ratio had strongest correlation with control (near ratio: r = -0.66, P = 0.001; distant ratio: r = -0.59, P = 0.001). Among patients with a fusional reserve ratio ≥ 2 at distance, 100% (5 of 5 patients) of these patients demonstrated good control (NCS ≤ 3).
Conclusions:
In children with intermittent exotropia, the total convergence amplitude was similar among different levels of control. The convergence reserve was lower in the poor control group. Fusional reserve ratio ≥ 2 was an indicator of good control in patients.
