An alternative clinical routine for subjective refraction based on power vectors with trial frames. (January 2017)

• Record Type: Journal Article
• Authors: María Revert, Antonia; Conversa, Maria Amparo; Albarrán Diego, César; Micó, Vicente
• Is Part Of: Ophthalmic and physiological optics. Volume 37:Number 1(2017:Jan.)
• Page Start: 24
• Page End: 32
• Publication Date: 2017-01
• Subjects: astigmatic decomposition -- power vectors -- subjective refraction -- trial frames; Ophthalmology -- Periodicals; Physiological optics -- Periodicals; Optometry -- Periodicals; Optics -- Periodicals; Vision -- Periodicals; 617.75
• DOI: 10.1111/opo.12343
• Languages: English
• ISSNs: 0275-5408

Abstract

Abstract: Purpose: Subjective refraction determines the final point of refractive error assessment in most clinical environments and its foundations have remained unchanged for decades. The purpose of this paper is to compare the results obtained when monocular subjective refraction is assessed in trial frames by a new clinical procedure based on a pure power vector interpretation with conventional clinical refraction procedures. Methods: An alternative clinical routine is described that uses power vector interpretation with implementation in trial frames. Refractive error is determined in terms of: (i) the spherical equivalent (M component), and (ii) a pair of Jackson Crossed Cylinder lenses oriented at 0°/90° (J0 component) and 45°/135° (J45 component) for determination of astigmatism. This vector subjective refraction result (VR) is compared separately for right and left eyes of 25 subjects (mean age, 35 ± 4 years) against conventional sphero‐cylindrical subjective refraction (RX) using a phoropter. The VR procedure was applied with both conventional tumbling E optotypes (VR1) and modified optotypes with oblique orientation (VR2). Results: Bland‐Altman plots and intra‐class correlation coefficient showed good agreement between VR, and RX (with coefficient values above 0.82) andanova showed no significant differences in any of the power vector components between RX and VR. VR1 and VR2 procedure results were similar ( p ≥ 0.77). Conclusions: The proposed routine determines the three components of refractive error in power vector notation [M, J0, J45 ], with a refraction time similar to the one used in conventional subjective procedures. The proposed routine could be helpful for inexperienced clinicians and for experienced clinicians in those cases where it is difficult to get a valid starting point for conventional RX (irregular corneas, media opacities, etc.) and for refractive situations/places with inadequate refractive facilities/equipment.