Exotropic angle by PACT vs under translucent cover
Reviewed by Fiona Rowe

The authors aimed to validate the photographic analysis with a translucent cover by comparing the results obtained from this analysis with the angle obtained by prism cover test (PACT) in patients with intermittent exotropia. This was a retrospective review of 270 patients who underwent surgery for intermittent exotropia and included patients with intermittent exotropia of 15-50PD with PACT measurements. Patients were excluded if having constant exotropia, paralytic exotropia, coexistent strabismus, ocular disease, high refractive error, anisometropia >1D and systemic disorders. PACT measurements were taken at one-third and five metres. Mean age was 8.4 ±6.1 years, mean exotropia was 27.0 ±6.1PD at distance and 29.2 ±7.2PD at near. Ninety patients wore glasses with a mean error of -0.52 ±1.59D. An exo drift of 4.5 ±3.3mm was noted. Mean estimated angle on photographs was 29.0 ±4.3PD. A positive correlation of drift, photographic angle and PACT angle was significant: r0.256 and 0.546 respectively. The eye showing the larger photographic angle was consistent with the non-dominant eye, for those with eye dominance. Factors that could affect discrepancy between photographs and real angles included older age, small distance angle and glasses wear. Limitations of this study included exclusion of all exotropia angles, those unable to do PACT and use of 2D photographs. However, the authors suggest use of this method may be useful for added clinical assessment and to assess impact on appearance.

Photographic assessment of intermittent exotropia using a translucent cover.
Chung SAh, Rhiu S, Park A, Yu J.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2021;58:331-8.