Nearly half of patients requiring vision correction are significantly astigmatic in at least one eye, findings from a new study, sponsored by Johnson & Johnson Vision Care, shows. Data from the study further reveals that the prevalence of astigmatism is almost double in patients with myopia (nearsightedness) compared to those with hyperopia (farsightedness). These findings were recently published in Eye & Contact Lens, the peer-reviewed journal of the Contact Lens Association of Ophthalmologists (CLAO).
“These findings provide useful information on the proportion of potential soft contact lens wearers requiring an astigmatic correction,” says co-author Graeme Young, PhD, FCOptom, DCLP. “Patients with astigmatism–even in just one eye–can benefit from advances in toric contact lens technology.”
“A number of previously published studies have shown significant improvements in visual acuity through fitting astigmats with toric soft lenses versus spherical lenses,” adds study co-author Anna Sulley, BSc, MCOptom, Clinical Affairs Manager, Johnson & Johnson Vision Care, Europe, Middle East and Africa. “Advances in lens design and materials, such as those featured in ACUVUE OASYS Brand Contact Lenses for ASTIGMATISM, have gone far to increase lens stability, improve eye comfort and make toric lenses easier to fit.”
To conduct the study, a large database of spectacle prescriptions was obtained from a UK optical retail chain with offices throughout Britain and was used to calculate the prevalence of astigmatism for various thresholds by eye and by patient. The analysis included patients aged eight to 70 years, which represents the population most likely to present for contact lens fitting. Astigmatism of 0.75D was used as the threshold for analysis because this is generally the lowest amount corrected with toric soft contact lenses.
Of the 11,624 patients in the database, nearly half (47.4 percent) demonstrated significant astigmatism (greater or equal to 0.75D) in at least one eye, and nearly a quarter (24.1 percent) exhibited significant astigmatism in both eyes. This proportion was higher for myopes, of whom 54.9 percent demonstrated astigmatism in at least one eye and 31.7 percent in both eyes.
Of the 47.4 percent of patients who had astigmatism, nearly half had significant astigmatism in one eye only. “Not all of these patients will need astigmatic correction; however, patients with monocular astigmatism who might benefit from correction include those with astigmatism in their dominant eye, an oblique axis, low sphere power, or previous history of unsatisfactory visual performance,” suggests Dr. Young.
The prevalence of astigmatism was approximately twice as high in myopes as in hyperopes and increased with spherical refractive error. In addition, the prevalence of astigmatism was lower in younger people (ages 20 and under). For example, the prevalence of patients with 0.75D or greater in both eyes was 21.4 percent in those 20 years of age or younger compared with 24.5 percent in those over 40 years.
“Although these numbers show young people have lower rates of astigmatism compared to adults, the numbers are still significant,” explains Ms. Sulley. “Children are less likely to report vision problems. By asking the right questions and correcting astigmatism with toric lenses, doctors can help young people to see more clearly at school and during sports, potentially helping them to perform better. Adults with astigmatism can also appreciate gaining an extra line of vision with full contact lens correction.”
