Ophthalmic Quality of Life and Its Association With Visual Function, Accommodative and Binocular Vision Performance in Keratoconus Patients: A Study Using Rasch Analysis‏.

PURPOSE: To investigate the relationship between ophthalmic quality of life with visual function and accommodative/binocular vision performance in patients with keratoconus (KCN), using the Keratoconus Outcomes Research Questionnaire (KORQ).

METHODS

Seventy patients with KCN were recruited in this study (average age: 27.04 ± 5.60). A Persian adaptation of the KORQ was developed, and its psychometric properties were evaluated through Rasch analysis. The associations between study variables and the KORQ subscales, activity limitations (AL-S) and symptoms (S-S), were evaluated through linear regression models.

RESULTS

The Persian KORQ demonstrated good psychometric properties after removing items 5 and 8 from the AL-S and items 4 and 5 from the S-S. The analysis showed a statistically significant direct association between the AL-S score and age (β: 0.280, P < 0.05). In addition, there was a statistically significant direct relationship between the AL-S score with best-corrected visual acuity in the better eye (β: 0.279, P = 0.048), binocular contrast sensitivity (β: 0.319, P = 0.033), and steep keratometry in the better eye (β: 0.409, p-0.007). The near negative fusional vergence parameters-blur (β: -0.460, P = 0.012), break (β: -0.403, P = 0.027), and recovery (β: -0.391, P = 0.033)-showed a statistically significant inverse association with the S-S score.

CONCLUSIONS

The Persian KORQ is a reliable tool for assessing ophthalmic quality of life in Persian-speaking patients with KCN. The KCN-related AL-S are primarily influenced by age, basic visual functions, and the severity of KCN in the better eye. Deficits in certain binocular vision metrics, particularly a diminished near negative fusional vergence amplitude, may contribute to the symptoms reported by patients with KCN.