Comparing Habitual and i.Scription Refractions

Balamurali Vasudevan


Purpose: Many patients voice concerns regarding poor night vision, even when they see 20/20 or better in the exam room. This could be due to the method of refraction, end point of subjective refraction, pupil size at scotopic or photopic light levels, etc. An i.Scription refines the traditional manifest subjective refraction based on ocular aberrations obtained from the Zeiss i.Profilerplus. The aim of this study was to investigate any differences between habitual and i.Scription refractions and their relationship to night vision complaints.

Methods: Habitual, manifest, and i.Scription refractions were obtained from both eyes. Low and high order aberrations of the subjects were recorded with the Zeiss i.Profilerplus. Root mean square (RMS) ocular aberration measurements were obtained at small (3mm) and maximum pupil sizes. Subjects also rated their difficulty with driving at night on a scale of 1-10.

Results: For the spherical and cylindrical comparison, the habitual and i.Scription difference was significant [(t=-3.12, p < 0.01), (t=5.39, p < 0.01)]  as was the subjective and i.Scription comparison [(t=-2.31, p=0.03), (t=-2.54, p=0.02)], respectively. There was no significant difference for the spherical equivalent. A strong correlation was noted between the spherical equivalent i.Scription refraction and low-order RMS ocular aberration values for the 3mm (p<0.01, r=-0.72) and maximum (p=0.01, r=-0.57) pupil sizes. The maximum pupil size measured in the i.Profilerplus instrument was 4.84 ± 1.04 mm. Based on a subjective questionnaire, 10 out of the 19 subjects had discomfort at night with a mean (SD) magnitude of 4(2.7).

Conclusion(s): There was a significant difference found between the habitual and i.scription as well as between the subjective and i.Scription refractions for the spherical and cylindrical components. Other factors such as neural processing or personality are likely important factors to be considered in future work.


Year: 2017

Program Number: 175410

Resource Type: Scientific Program

Author Affiliation: Midwestern University, Arizona College of Optometry

Co-Authors: Nicole Putnam, Andre Juarez, Dr. Camtu Le, Kristine Sam, Pablo Gracia, Allissun Hoppert

Co-Author Affiliation: Midwestern University, Midwestern University, Midwestern University, Midwestern University, Midwestern University, EyeTeach Associates

Room: Hall D