Vertical imbalance induced by prism-ballasted soft toric contact lenses fitted unilaterally

• Published in: Ophthalmic & physiological optics Vol. 28; no. 2; pp. 157 - 162
• Main Authors: Nilsson, M., Stevenson, S. B., Leach, N., Bergmanson, J. P., Brautaset, R. L.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2008; Blackwell
• Subjects: adaptation; Adaptation, Ocular - physiology; Adult; Analysis of Variance; binocular vision; Biological and medical sciences; Contact Lenses, Hydrophilic; Convergence, Ocular - physiology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Humans; Medical sciences; Medicin och hälsovetenskap; Middle Aged; Oculomotor disorders; Ophthalmology; prism-ballasted; prism-stabilized; Prosthesis Design; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Refractive Errors; soft toric contact lens; Strabismus - etiology; Vertebrates: nervous system and sense organs; vertical fixation disparity; vertical heterophoria; Vision Disparity; Vision, Binocular - physiology; Visual Acuity; Heterophoria; Soft lens; prism-ballasted; soft toric contact lens; Strabismus; Contact lens; Instrumentation therapy; Eye disease; Fixation; Toric lens; prism-stabilized; vertical fixation disparity; vertical heterophoria; Binocular vision; Disparity; Ophthalmology; Oculomotor syndrome; Prism; Adaptation
• ISSN: 0275-5408; 1475-1313
• DOI: 10.1111/j.1475-1313.2008.00538.x

Fitting a prism‐ballasted soft toric contact lens unilaterally may potentially induce a vergence error that the subject cannot compensate. In the present study, a prism‐ballasted (1.5Δ base down) soft toric contact lens was fitted in the right eye only of 10 subjects with normal binocular vision. The effect on binocular vision was evaluated by measuring vertical phoria adaptation and vertical fixation disparity adaptation. The results show that the vertical vergence error induced was well compensated and fully adapted to. However, care might be needed when fitting these lenses unilaterally in subjects with vertical phoria‐related problems.