Soft Contact Lenses – Materials, Manufacturing, and Screening Practice Test

Measuring binocular vision status before fitting contacts focuses on how the eyes work together to maintain single, clear vision, especially at near. The essential parts are accommodation and convergence. Accommodation is the eye’s ability to change focus as objects come closer or farther; testing the amplitude and stability of accommodation helps predict whether the patient will sustain sharp vision through the lenses during reading or near tasks. Vergence or convergence is how the eyes align when looking at near objects; assessing near and distance vergence ranges, along with tests like the near point of convergence, reveals whether the eyes can maintain single vision without strain while wearing contact lenses.

Prismatic correction is included because identifying a phoria or tropia—an alignment tendency that isn’t fully compensated by the eyes’ vergence system—guides management. If a significant misalignment exists, prism may be needed in spectacles to support comfortable binocular vision, even if the patient plans to wear contacts. This helps ensure that wearing CLs won’t be limited by unresolved alignment issues.

Divergence excess by itself misses the broader picture of how accommodation and convergence work together, and stereoacuity and color vision, while useful in some screenings, don’t directly address how well the eyes team for real-world wear. Pupillary reflex and ocular dominance are less central to the binocular function needed for an initial contact lens fit, though ocular dominance can influence later choices like monovision.