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Study evaluates negative spherical aberrations in contact lenses
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Contact lenses incorporating negative spherical aberration do not improve vision in nonpresbyopic adult myopes, according to a study conducted at the Brien Holden Vision Institute in Sydney, Australia.
Thirty-two patients between 18 and 35 years old with myopic refractive error from – 0.50 D to – 6.00 D and cylinder less than 1D were included. They were randomly assigned to wear for two consecutive periods of at least 5 days and a minimum of 6 hours a day Johnson & Johnson Vision’s 1-Day Acuvue Moist lens with negative spherical aberration (SA) and a test lens with minimal or no SA.
The lens with added negative SA showed no advantage in visual performance. No statistically significant differences were found between the two lenses for high contrast and low contrast visual acuity, horizontal heterophoria, accommodative facilities and near stereopsis.
Subjective satisfaction was assessed through a questionnaire. No difference was found between lenses for clarity of vision, nor for willingness to purchase the lenses. Vision stability ratings were better with the test lens when combined for day and night conditions. According to the authors, this might be due to slightly tighter lenses or to better neuroadaptation to a lens not interfering with the inherent aberrations profile of each subject.
The authors concluded that the advantages of introducing negative SA in contact lenses are negligible and said to be concerned that the power profile of these lenses may affect peripheral refraction, inducing relative peripheral hyperopia.
“Given current clinical interest in the peripheral retina in relation to myopia, clinicians should be aware of the insignificant visual performance gains when fitting soft contact lenses of this design on young and progressing myopes,” they wrote.
“Clinicians should be aware that most single vision contact lens designs incorporate negative spherical aberration,” study co-author Ravi C Bakaraju, BOptom, PhD, FAAO, told Primary Care Optometry News. “In light of peripheral hyperopia theory, practitioners may need to reconsider prescribing such lenses to young myopic patients, as these lenses have a potential to induce peripheral hyperopia while offering minimal or no benefits to improve visual performance.” – by Michela Cimberle
Disclosure: None of the authors reported relevant financial disclosures.
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