Stereoacuity with balanced presbyopic contact lenses
(Acuité stéréoscopique chez des patients équipés en lentilles pour presbytes)

Ferrer-Blasco T, Madrid-Costa D.
Optometry Research Group (GIO), Optics Department, University of Valencia
C/o Dr Moliner 50, Burjassot, Valencia, Spain.
teresa.ferrer@uv.es

BACKGROUND : To evaluate near stereoacuity with the balanced Proclear Multifocal simultaneous vision contact lens.

METHODS : Twenty-five presbyopic subjects were fitted binocularly with the Proclear Multifocal contact lens and with distance contact lenses combined with reading spectacles, which served as controls. After one month, stereoacuity was measured using the vectographic Titmus and Random dot stereotests and the Howard-Dolman (HD) apparatus under photopic conditions (85 cd/m(2) ) at 40 cm. Binocular high-contrast visual acuities (BHCVA) at distance and near were examined.

RESULTS : For the multifocal group, mean stereoacuity with the Howard-Dolman method was 22.40 ± 8.23 seconds of arc. Using the Titmus and the Random dot sterereotests, the values were 56.40 ± 18.00 and 54.80 ± 20.23 seconds of arc, respectively. For the SCL group, mean stereoacuities were 19.9 ± 4.6, 51.2 ± 16.4 and 51.2 ± 20.88 seconds of arc, with the Howard-Dolman, Titmus and the Random dot, respectively. There were no statistically significant differences among groups for Howard-Dolman (p = 0.07), Titmus (p = 0.10) and Random dot (p = 0.17) stereotests. No statistically significant differences were found between the Titmus and the Random dot stereotest values (multifocal group: p = 0.30 and SCL group: p = 0.50), however, these values differ significantly from those found using the Howard-Dolman method for both groups (p < 0.001). For the multifocal group, BHCVA was -0.007 ± 0.060 and 0.012 ± 0.063 logMAR for distance and near vision, respectively. For the SCL group, these values were -0.02 ± 0.05 and -0.01 ± 0.06 logMAR, for distance and near vision, respectively. Comparing both groups there were no statistically significant differences between groups for either distance (p = 0.08) or near (p = 0.09).

CONCLUSIONS : The Proclear Multifocal contact lens provided good distance and near visual acuity preserving stereopsis. Multifocal optics with one lens biased to distance viewing and the other lens biased toward near viewing minimally affects stereoacuity.

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