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Updated: Aug 5, 2026
Virtual Prism Adaptation Therapy: Protocol for Validation in Healthy Adults
Published on: February 12, 2020
Short-Term Effect of Prismatic Lenses in Head Positioning and Kinematics in Patients with Postural Deficiency
João Alves da Silva1, Fábio Trindade2, Ivo Álvares Furtado2
1Centro Académico de Medicina de Lisboa, Universidade de Lisboa, 1649-028 Lisbon, Portugal.
Background:
Asymmetries in head movement are common in postural disturbances. The correction of such changes using prismatic lenses has been reported but not quantified.
Methods:
A controlled randomized double-blind prospective study was performed on a population with Postural Deficiency Syndrome, comparing active head extension and rotation using prismatic and sham lenses. The evaluation was carried out using clinical photography and goniometer before intervention and 15 min after lenses' application.
Results:
One hundred patients were included. The initial extension from a horizontal gaze was 53.2±12.6°, and the rotation amplitude was 113±15.2°. The overall head movement was below the standard reference values of 75° for head extension and 160° for rotation. (p<0.01 for both variables). The intervention group exhibited both an extension increase and rotation increase in amplitude: rotation improved by 8.7±9.9° (p<0.01), and extension increased on average 6.5±8.0° (p<0.01). The initial head rotation asymmetry was 10.1±4.3°, reducing to 1.70±1.58° after intervention (p<0.01).
Conclusions:
Patients with Postural Deficiency Syndrome have a limited and asymmetrical range of motion of head rotation and extension. These limitations are responsive to the use of low-powered prismatic lenses.
