Binocular vision disorders can interfere with patients’ visual activities and greatly affect quality of life. Previous studies have evaluated convergence insufficiency in various age cohorts but with significant differences across the board, so this time around, researchers in Tehran conducted the first population-based study to examine the prevalence of convergence insufficiency specifically in the geriatric population.

Subjects older than 60 years were selected at random and underwent a complete ocular examination, including visual acuity, refraction and binocular vision assessments. The eye movement evaluation included unilateral and alternating cover tests and measurement of the near point of convergence and positive fusional vergence.

Of almost 1,800 participants, the overall prevalences of two-sign and three-sign convergence insufficiency were 30% and 22%, respectively; there were no statistically significant differences between men and women. The highest and lowest prevalences were in the age groups 70 to 74 and 75 to 79 years, respectively; there was no significant trend correlated with age.

The authors proposed two theories to explain the significant prevalence of convergence insufficiency in the geriatric population: (1) the effects of absolute presbyopia on the accommodative vergence component of the total convergence and (2) the induced base-out prismatic effect of plus lenses, “which can cause a decompensated near exophoria by increasing the demand on the near positive fusional vergence,” the authors noted in their study.

In addition, the authors suggested the absence of age-related association with prevalence was because the presbyopia process is almost complete by age 60.

No significant relationship was observed between the convergence insufficiency and sex, but the authors note there have been conflicting results in previous studies. “Some reported a higher prevalence of convergence insufficiency in women than in men and attributed this finding to the higher number of women seeking optometric care, as well as the possibility of sex-related differences in binocular vision performance,” the authors explained.

With this high frequency of convergence insufficiency, the authors suggest clinicians should give more attention to this vision disorder in this age group.