An alternative clinical routine for subjective refraction based on power vectors with trial frames

Revert, Antonia María; Conversa, Maria Amparo; Diego, César Albarrán; Micó, Vicente

doi:10.1111/opo.12343

Cited by 6 publications

(11 citation statements)

References 31 publications

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“…Previous work 19 demonstrated that power vector refraction can be measured directly using a set of handheld JCCs with discrete powers, and not just computed from spherocylindrical prescriptions. It was concluded that the next…”

Section: Discussionmentioning

confidence: 99%

“…However, their most extended use comes from determining dioptric power in sphero‐cylindrical form, transforming these findings to power vector notation and applying further analysis. Few attempts have been described to measure the refraction in vector format directly, 16 ranging from the Humphrey Vision Analyzer 17 (HVA) based on the astigmatic decomposition proposed by Gartner, 18 to the more recent methodology using Thibos's power vectors 19 …”

Section: Introductionmentioning

confidence: 99%

“…Few attempts have been described to measure the refraction in vector format directly, 16 ranging from the Humphrey Vision Analyzer 17 (HVA) based on the astigmatic decomposition proposed by Gartner, 18 to the more recent methodology using Thibos's power vectors. 19 In previous work by Revert et al, 19 it was demonstrated that refraction can be measured directly in power vector notation using a handheld JCC and trial lenses. This clinical procedure was less agile when compared with the use of a phoropter, thereby slowing down the procedure and increasing the probability of errors in alignment when changing from one handheld JCC to another.…”

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confidence: 99%

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Subjective refraction using power vectors by updating a conventional phoropter with a Stokes lens for continuous astigmatic power generation

Moreno¹,

Micó

Albarrán-Diego

2023

Ophthalmic Physiologic Optic

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PurposeTo implement a pure power vector method for monocular subjective refraction using a regular phoropter with the only modification being the inclusion of a Stokes lens. The proposed methodology was tested with three different Stokes lenses, and the results were compared with conventional clinical refraction procedures.MethodsPower vector subjective refraction was performed by attaching a Stokes lens to the Risley prism holder. Stokes lenses allow for pure astigmatic compensation in the form of the J0, J45 components while the spherical lenses in the phoropter allow determination of the spherical component in the form of M (spherical equivalent). The proposed routine is presented step‐by‐step using three Stokes lenses having different astigmatic powers.ResultsMonocular subjective refraction was performed on 26 healthy subjects with a mean age of 44 ± 16 years, mean spherical equivalent of −0.56 D (range −5.50 to +2.38 D) and refractive astigmatism ≤1.50 D. No differences were found between the results obtained with the conventional technique versus the vector‐based procedure for the spherical equivalent (p = 0.28) or astigmatic components (p = 0.34). In addition, visual acuity (VA) was equivalent through the refractions measured with the conventional and vector procedures (p = 0.12). Repeatability coefficients for J0 and J45 with the new vector methodology were <0.38 D.ConclusionsThe proposed routine could be helpful for cases where it is difficult to get a valid starting point for conventional refraction (e.g., irregular corneas and media opacities), for testing facilities with limited resources/equipment and/or for motivated clinicians who wish to know about alternative methods of refractive error determination.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Subjective refraction using power vectors by updating a conventional phoropter with a Stokes lens for continuous astigmatic power generation

Moreno¹,

Micó

Albarrán-Diego

2023

Ophthalmic Physiologic Optic

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“…Instead of using an old Risley prism mount as in the work reported by Ferrer-Altabás and Micó, 34 we employed more recent mounts coming from Nidek phoropters as well as included an angular dial to directly measure the angle variation between cylinder axes in degrees (not in prism diopters as in previous work), thus, making its usability/readability much more comfortable and easier to use. These lenses take part in a different study (not included in this manuscript) for refractive error compensation following alternative subjective routines 36 and because of that, they are labeled with QR codes to prevent easy identification of them and to avoid bias in the data (it is worth noting that this encryption is not relevant for this paper). Thus, this manuscript presents the technical validation of a set composed of three lab-made Stokes lenses in which the measured dioptric power profiles generated by each Stokes lens are compared with the corresponding theoretical prediction (as in previous work 34 ), but here we include a statistical analysis (paired t-test, boxplots, and Bland–Altman graphs) of the measurements, thus expanding upon and completing the characterization reported in previous work 34 .…”

Section: Introductionmentioning

confidence: 99%

Validation of a set of compact and low-cost Stokes lenses aimed at refractive astigmatism measurement for optometric practice

Albero-Moreno¹,

Albarrán-Diego

Micó

2022

Opt. Eng.

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.We describe the construction and characterization of three Stokes lenses that can be used in optometric practice to measure different ranges of refractive astigmatism using subjective routines. The proposed set of Stokes lenses is assembled from Risley prism mounts coming from a Nidek phoropter in which the optical prisms are replaced by three different sets of cylindrical lenses ( ± 0.75, ± 1.25, and ± 1.75 D) coming from a trial lens case to cover a different astigmatism range (1.5, 2.5, and 3.5 D in modulus, respectively). We present the experimental characterization of the three Stokes lenses with the power vector notation and use an automatic lensmeter (Topcon CL-300) for dioptric power measurement. The measured dioptric power profiles are in concordance with the theoretical predictions, and statistical testing reveals no differences between measured and theoretical values for the three lenses, neither in spherical nor in cylindrical components (p ≥ 0.05 for all cases). Bland–Altman plots show very good agreement between measured and theoretical values with limits of agreement below 0.12 D for both M and J components for the three lenses. These Stokes lenses can be easily constructed from regular Risley prism mounts, so they can be used in almost any phoropter model for refractive error compensation.

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“…Fan and Block methods for measuring cylinder power involve making judgments about which of a pair of perpendicular grids are clearer, and adjusting astigmatism correction until they are equally clear 1,8 . Other, more recent, vector‐based procedures for measuring astigmatism 9–12 can also be considered psychophysical procedures.…”

Section: Introductionmentioning

confidence: 99%

Bearing fixing: A new computer algorithm method for subjective determination of astigmatism

Carkeet

Choo

2021

Ophthalmic Physiologic Optic

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Purpose This article aims to illustrate the principles of bearing fixing, a new computer‐controlled procedure for subjective determination of astigmatism, and to compare it with conventional clinician‐controlled Jackson crossed‐cylinder refraction. Methods The principles and method for bearing fixing are described. Astigmatism was measured using bearing fixing and Jackson cross‐cylinder twice on 20 visually normal participants aged between 18 and 34 years. After final sphere adjustment, acuity measurements were made with each refraction estimate. Results Bearing fixing results could be obtained for all participants. Mean bearing fixing cylinder magnitude was slightly higher than Jackson cross‐cylinder measures of cylinder magnitude, by 0.05D. Using vector analysis to take into account cylinder power and axis, mean bearing fixing astigmatism was not significantly different from cross‐cylinder astigmatism, but did have higher test‐retest variability (p < 0.05). Acuity with bearing fixing and cross‐cylinder corrections did not significantly differ in average value or repeatability. Conclusions Bearing fixing is a feasible method for subjective determination of astigmatism, and there are a number of potential improvements to the method which could make it faster and more precise.

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An alternative clinical routine for subjective refraction based on power vectors with trial frames

Cited by 6 publications

References 31 publications

Subjective refraction using power vectors by updating a conventional phoropter with a Stokes lens for continuous astigmatic power generation

Subjective refraction using power vectors by updating a conventional phoropter with a Stokes lens for continuous astigmatic power generation

Validation of a set of compact and low-cost Stokes lenses aimed at refractive astigmatism measurement for optometric practice

Bearing fixing: A new computer algorithm method for subjective determination of astigmatism

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