Prismatic contact lens correction vs prismatic glasses
Reviewed by Fiona Rowe

The aim of this study was to verify if diplopia could be corrected by applying soft directional prism contact lenses, to compare effectiveness of diplopia correction, comfort and quality of vision with these contact lenses compared to prism glasses. This was a prospective study of patients with vertical and / or horizontal diplopia and small angle strabismus (≤8PD). Prism contact lenses were worn in both eyes with split correction to obtain a good balance of vision. The maximum prism strength was 3.5PD horizontal and 4.5PD vertical with an inferior base. Checks were made at one and six months of contact lens wear. Eight patients were included aged 12 to 60 years. All had diplopia correction with contact lenses and were orthophoric. None had pain or discomfort and had good correction of diplopia in secondary gaze positions unlike with prism glasses. Best corrected visual acuity remained unchanged. All patients preferred the prism contact lenses over glasses. It was also possible to build in spectacle prescriptions. The limit of the prism strength within contact lenses was 5PD in any axis. However, they advise a maximum of 1.5PD with superior base, 3.5PD horizontal and 4.5PD with inferior base. This option reduces prismatic aberrations significantly in comparison to glasses and is proposed as a useful alternative to prism glasses for a select group of patients.

Application of soft directional prismatic contact lenses to correct diplopia.
Parolini B, Penzani R, Pascotto P.
JOURNAL OF PEDIATRIC OPHTHALMOLOGY AND STRABISMUS
2023;60(3):248-52.