Abstract
Purpose :
An essential factor for a successful refraction assessment is the control of accommodation. Fogging is a technique for relaxing accommodation using plus power lenses instead of drugs. However, the optimal amount of power and time of application of plus lenses remain unclear. This study tested which power and time of application of fogging lenses are more adequate to achieve the maximum relaxation of accommodation (RoA).
Methods :
We analyzed the accommodative response of 20 young adults, 7 males and 13 females, between 18 and 30 years old when lenses of different amount of plus power were placed in front of the patient’s eye. For each patient, six different fogging lens powers relative to the manifest refraction were tested (+1D, +1.5D, +2D, +2.5D, +3D and +4D). Each lens was placed in front of the eye for 55s while the patient was looking at a VA chart placed at 6m. During that time, changes in accommodation were monitored at 10Hz frequency by means of a Hartmann-Shack aberrometer. During measurements contralateral eye was occluded. Lenses were presented in a random order, with a wash-up time between trials of 90s.
Results :
The mean age of participants was 24.7±3.4 years, with a mean refractive error in terms of spherical equivalent of -0.59±1.37D ranging from -4.25D to +1D. The mean RoA for all lenses was -0.05±0.22D and the mean time for achieving the maximum RoA was 24.75±16.52s.
Analyzing the cases in which the RoA was at least 0.12D, the mean RoA was 0.23±0.08D with a mean time to achieve the maximum RoA of 19.94±11.52s. Lenses that produced a better RoA were those with powers between +1D and +2.5D. Conversely, when analyzing the cases in which the RoA was under -0.12D, meaning that accommodation was activated, the mean RoA was -0.29±0.17 with a mean time to get the maximum accommodation of 40.86±11.18s. Lenses that produced a higher activation of accommodation were +3D and +4D.
Conclusions :
Real time monitorization permits to determine power and time of fogging lenses. Better results were obtained for powers between +1D and +2.5D and a time of application of approximately 20s. The countereffect of high-power fogging lenses was seen in lenses of +3D and +4D, that could lead accommodation to the resting state due to the high blur. Further research with a larger sample should be performed to confirm these preliminary results.
This is a 2021 ARVO Annual Meeting abstract.