Changes in accommodative micro-fluctuations after wearing contact lenses of different optical designs

Abstract

A B S T R A C TPurpose: Accommodative micro-fluctuations (AMF) are small dioptric changes during accommodation. The aim of this study was to evaluate and compare changes in AMF when wearing silicone hydrogel contact lenses of two different optical designs. Methods: A multi-centre, randomised, cross-over, non-dispensing study was conducted on 68 adapted contact lens wearers aged 25-35 years to compare AMF responses to a spherical and aspheric silicone hydrogel (comfilcon A) lens designs. A Righton Speedy "i" series Auto Refractometer in accommodation analyser mode was utilized before and after reading a standard text in font size 8 on an iPhone 5 for 20 min at a 25 cm viewing distance. Phone screen brightness was set by automatic adjustment mode and ambient illumination was controlled at all sites. Results: Mean ± SD AMF change from before to after the reading task was 2.25 ± 5.6 and 0.13 ± 5.7 (relative values) for the spherical and aspheric lens designs, respectively. The difference was statistically significant (P = 0.017, Paired t-test). Conclusions: The smaller change in AMF when using an aspheric lens design suggests reduced ciliary muscle stress when reading print on a smart phone at a close distance for short periods (20 min). Contact lens wearers who frequently use digital devices and are experiencing eye strain may benefit from switching from a spherical design to one that incorporates aspheric optics.

Multifocal contact lens design, not addition power, affects accommodation responses in young adult myopes

“…Another investigation compared a spherical SV contact lens to a ‘multiple aspheric curve design’ in myopic adults aged 20–35 years and found a lower change in accommodative microfluctuations in the novel lens after a 20‐min reading task. This was described as an ‘objective measure of eye strain’ 38 …”

Myopia-correcting lenses decrease eye fatigue in a visual search task for both adolescents and adults

“…One potential explanation for this result may be related to changes in accommodation stemming from the additional optical power of the lens: as is known, small dioptric changes in the so-called accommodative micro-fluctuations (AMF) during the accommodation process results in continued eye stress. This was used by Kajita et al [ 44 ], who compared spherical lenses with aspherical lenses via AMF variation during screen reading and confirmed that the aspheric lens design reduced ciliary muscle stress. Hence, the lens’s design was able to diminish regulatory muscle activity, leading in turn to reduced eye tiredness.…”

Comparison of Accommodation and Accommodative Micro-Fluctuation After Implantable Collamer Lens and LASIK Surgery for Myopia

“…The ACOMOREF 2 (Righton, Japan) with AMF mode was used to record the MFs outcomes in this study [15]. It is an infrared optometer with a spectral power calculation to analyze and record the non-stationary spectrum of MF.…”

“…Moreover, one previous study showed that high-frequency (1.3 to 2.2 Hz) of MFs represent tension of the ciliary muscle, that is, when the ciliary muscle contraction load increases, the HFC increases [14]. The ACOMEREF refractometer (Righton, Japan), which uses infrared light to record the HFC of MFs under different accommodative stimuli, has been proven to be useful to objectively evaluate the stress of the ciliary muscle [15].…”