Binocular vision parameters in keratoconic eyes wearing scleral lenses

Binocular vision anomalies are common in individuals with keratoconus (KC) corneas and can significantly impact visual function, comfort, and quality of life. Understanding how ocular conditions influence accommodative and vergence parameters is essential for accurate assessment and effective management, especially in patients requiring speciality contact lenses such as scleral lenses (SL) for visual rehabilitation.

The aim of this work is to evaluate the changes in binocular vision parameters in eyes with KC wearing SLs.

Binocular vision parameters (accommodative and vergence) were assessed at baseline, after 6 h and 1 month of SL wear in 16 KC participants. Convergence insufficiency symptom survey (CISS) was employed to assess binocular vision disorder-related symptoms.

A statistically significant improvement in visual acuity was observed after 6 h and 1 month of SL wear (p < 0.05). Stereopsis showed a significant improvement after 6 h (p = 0.002) and 1 month (p = 0.001) of SL wear compared to baseline. Near point of convergence break showed significant improvement after 1 month (p = 0.002) when compared to baseline and between 6 h and 1 month (p = 0.003) SL wear. Near point of convergence recovery showed significant improvement after 1 month of SL wear (p = 0.005). Positive fusional vergence improved at distance recovery (p = 0.01) and near break and recovery (p = 0.03, p = 0.01) after 6 h and 1 month of SL wear. Vergence facility at near improved significantly after 6 h and 1 month of SL wear compared to baseline (p < 0.001). Statistically significant improvement was observed for the binocular amplitude of accommodation (p = 0.009) and negative relative accommodation (p = 0.003) after 1-month SL wear. Binocular accommodative facility also showed significant improvement after 6 h (p = 0.009) and 1 month (p = 0.003) of SL wear. CISS scores significantly improved after 1 month of SL wear (p < 0.001).

SLs effectively enhance vision, help maintain proper eye alignment, improve binocular function, and reduce asthenopia symptoms in KC patients. Comprehensive orthoptic examinations are crucial for addressing these issues in KC.