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Table of Contents
ORIGINAL ARTICLE
Year : 2020  |  Volume : 2  |  Issue : 1  |  Page : 17

Analysis of high-order aberrations in the eyes of elite police officers from the military police of São Paulo


1 UPO-Paulista Ophthalmology Unit, UNIFESP-Federal University of São Paulo, Brazil
2 Departament of Ophthalmology, UNIFESP-Federal University of São Paulo, Brazil
3 Departament of Ophthalmology, FCMSCSP-College of Medical Sciences of Santa Casa of São Paulo, Brazil

Date of Submission07-Apr-2020
Date of Decision10-Jan-2020
Date of Acceptance20-Apr-2020
Date of Web Publication24-Jul-2020

Correspondence Address:
Dr. Vitor Ruda Silva Aragão
1375 Timbiras Street, 1101 apartament, Belém, PA, 66033-331
Brazil
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/PAJO.PAJO_17_20

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  Abstract 


Background: Recent advances in ophthalmic evaluation technology allow the measurement and quantification of high-order optical aberrations (HOAs). Several professionals have superior visual function compared to the general population.
Objective: This study is to characterize the profile of HOAs in the elite police of the São Paulo military police.
Material and Methods: This is an observational clinical study of a case series with 42 eyes of 21 patients. The objective was to compare HOAs between snipers and civilians, through assessments of visual acuity and ocular aberrometry. The patients were divided into two groups: elite and control according to their profession. The elite group had more eyes with visual acuity better than or equal to 20/15.
Results: The elite group had slightly lower values of higher order aberrations: 0.26 and 0.29 in the elite group and 0.30 and 0.31 in the control group. It was possible to verify that visual acuity both with and without correction was better in patients in the Elite group, even though high-order aberrations did not present significant differences in the mean.
Conclusion: It was possible to verify that visual acuity both with and without correction was better in patients in the Elite group, even though high-order aberrations did not present significant differences in the mean values.

Keywords: Ocular, ophthalmology refraction, police, refractive errors, visual acuity Ocular, ophthalmology refraction, police, refractive errors, visual acuity


How to cite this article:
Silva Aragão VR, Miyashiro RA, Moscovici BK, S. Malta JB, Queiroz Campos MS, Santos RR, Nakano C. Analysis of high-order aberrations in the eyes of elite police officers from the military police of São Paulo. Pan Am J Ophthalmol 2020;2:17

How to cite this URL:
Silva Aragão VR, Miyashiro RA, Moscovici BK, S. Malta JB, Queiroz Campos MS, Santos RR, Nakano C. Analysis of high-order aberrations in the eyes of elite police officers from the military police of São Paulo. Pan Am J Ophthalmol [serial online] 2020 [cited 2020 Nov 25];2:17. Available from: https://www.thepajo.org/text.asp?2020/2/1/17/290578




  Introduction Top


Recent advances in technology in ophthalmological evaluation allow the measurement and quantification of high-order optical aberrations (HOAs) such as trefoil coma and spherical aberration, as well as the known low-order optical aberrations such as defocus and astigmatism. A standardized nomenclature has been developed to describe ocular aberrations in terms of an expansion of the Zernike pyramid and its wavefront aberrations.[1],[2]

Individually, any Zernike aberration decreases the optical quality of the retinal image and can systematically reduce visual function.[3],[4] However, when different types of aberrations are combined, they interact in complex ways, and it is difficult to predict visual function based on knowledge of the systematic effects of individual aberrations.[5]

The effect of optical aberrations on visual function depends on the visual nature. There is little correlation, for example, between high-contrast visual acuity, high-luminance letters, and retinal image quality of normal eyes that are fully corrected for spherical and cylindrical refractive errors. This suggests that neural factors contribute a large part of individual variability in distance-corrected visual acuity under normal conditions.

However, if visual function is quantified through low-contrast visual acuity and/or low-luminance targets, optical quality plays an important role in individual variability in functional performance.[6],[7],[8],[9]

The effect of optical aberrations on visual function depends on the specific combination of high-order aberrations in the eye. For example, when spherical aberration is present, a small amount of defocus is needed to optimize visual acuity.[10],[11],[12]

Although this additional defocus increases the total amount of aberration (quantified by the root mean square [RMS] between defocus and spherical aberration increases the optical quality of the eye), quantified by the fraction of the pupillary area for which the wavefront error is small. The result is an increase in visual acuity because one type of aberration nullifies the harmful effect of another type of aberration.

Although the vast majority of elite police officers have a visual acuity equal to or better than 20/20, many can be limited by uncorrected HOAs.

Thus, this group of “visual elite ”can benefit from refractive corrections designed to improve image quality in the presence of HOAs.

Objective

The objective was to compare HOAs between snipers and nonsnipers, through assessments of visual acuity and aberrometry.


  Methodology Top


This is an observational clinical study of case series.

Study design and patient selection

Forty-two eyes of 21 patients (11 elite military policemen and ten normal individuals) with visual acuity without correction better than or equal to 20/25, with a minimum age of 18 years, and who signed the informed consent form were evaluated. Exclusion criteria were patients with systemic or ocular diseases such as diabetes, anterior or posterior uveitis, corneal dystrophies or degenerations, glaucoma, retinal diseases, and previous eye surgery.

The 21 patients who met the inclusion criteria in the study and who signed the informed consent form, underwent visual acuity, refraction, and aberrometry tests in both eyes.

The characterization of the sample is shown in [Table 1] and [Table 2].
Table 1: Descriptive results of elite police-1

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Table 2: Descriptive results of normal individuals-1

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The patients were divided into two groups: elite and control, according to their profession (elite, all components of the GATE(Special Tactical Action Group) and control snipers, all other patients were designated as elite).

Evaluation of patients

A complete ophthalmological evaluation was performed, with visual acuity (VA) measurement without and with correction using the Snellen table, dynamic and static refraction under cycloplegia, biomicroscopic evaluation with slit lamp, applanation tonometry, retinal mapping, and aberrometry.

The aberrometry was performed under cycloplegia, with a 6-mm pupil using the LADARWave device (Alcon, Forth Worth, Texas, USA).

The RMS of high-order aberrations was used for this work.


  Results Top


The elite group had a greater number of eyes with visual acuity better than or equal to 20/15: 16 without correction and 19 with correction [Table 1].

It also presented only one eye with visual acuity without correction <20/20 [Table 1].

The control group did not have eyes with visual acuity ≤20/15 [Table 4] and presented seven eyes with visual acuity without correction <20/20, and none with this acuity when corrected.

Regarding the spherical equivalent (in module), the elite group presented slightly higher mean values (0.42 in right eye and 0.45 in left eye) compared to the control group (0.27 in right eye and 0.39 in left eye).

In contrast, the elite group showed slightly lower values of high-order aberrations: 0.26 (right eye) and 0.29 (left eye) in the elite group and 0.30 (right eye) and 0.31left eye) in the control group [Table 1] and [Table 2].


  Conclusion Top


This is a small sample series of cases, limited by the small number of GATE snipers, so it is difficult to reach conclusions.

It was possible to verify that visual acuity with and without correction was better in patients in the elite group, even though high-order aberrations did not present significant differences in the mean. The best number of HOAs was found in the elite group, and these patients had excellent acuity, yet none of the patients in both groups had elevated HOAs. Therefore, it was not possible to establish an objective relationship between HOAs and visual acuity.

Another limitation of this study was the fact that this aberrometer requires pupil dilation, and it is well known that the HOAs are directly correlated with the pupil size. In the daily or work activities of both groups, it is unusual to have the pupil as large at the moment of the examination (probably only at night), so it is not possible to confirm a direct relationship between the HOAs with pupil dilation and the performance at daytime activities.

There are controversial data about the possibility of training visual performance. Randle found that it is possible to control accommodative systems and could extend their fair point.[13],[14] Balliet et al. tried to train visual acuity and had improvements in their study without refractive changes.[14],[15]

It was noticeable that the elite group had a larger spherical equivalent (in module), but in both groups, they did not present values >1 D. In the work with baseball players, there were also no players with high HOAs.[13]

Garland et al. revised the influence of the visual acuity, dynamical refraction, and cognition differences (such as memory for game situations and decision accuracy) and found that cognition was more related with better performances.[16]

Four patients in the elite group had extremely low HOAs, close to 0.1. The remainder at the most 0.5 and even these patients arrived at 20/15 visual acuity.

The question remains as to the reason for the best visual acuity in the elite group: training, persistence, chance?

To answer this question, it is necessary to carry out a randomized study with a larger number of participants.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
American National Standards Institute, Inc. American National Standards for Ophthalmics – Methods for Reporting Optical Aberrations of Eyes. United States: American National Standards Institute, Inc Z80; 2004. p. 28.  Back to cited text no. 1
    
2.
Thibos LN, Applegate RA, Schwiegerling JT, Webb R; VSIA Standards Taskforce Members Vision science and its applications. Standards for reporting the optical aberrations of eyes. J Refract Surg 2002;18:S652-60.  Back to cited text no. 2
    
3.
Applegate RA, Ballentine C, Gross H, Sarver EJ, Sarver CA. Visual acuity as a function of Zernike mode and level of root mean square error. Optom Vis Sci 2003;80:97-105.  Back to cited text no. 3
    
4.
Applegate RA, Sarver EJ, Khemsara V. Are all aberrations equal? J Refract Surg 2002;18:S556-62.  Back to cited text no. 4
    
5.
Applegate RA, Marsack J, Ramos R, Sarver EJ. Interaction between aberrations can improve or reduce visual performance. J Cataract Refract Surg 2003;29:1487-95.  Back to cited text no. 5
    
6.
Pepose JS, Applegate RA. Making sense out of wavefront sensing. Am J Ophthalmol 2005;139:335-43.  Back to cited text no. 6
    
7.
Applegate RA, Marsack JD, Thibos LN. Metrics of retinal image quality predict visual performance in eyes with 20/17 or better visual acuity. Optom Vis Sci 2006;83:635-40.  Back to cited text no. 7
    
8.
Applegate RA. Glenn fry award lecture 2002: Wavefront sensing, ideal corrections, and visual performance. Optom Vis Sci 2004;81:167-77.  Back to cited text no. 8
    
9.
Marsack JD, Thibos LN, Applegate RA. Metrics of optical quality derived from wave aberrations predict visual performance. J Vis 2004;4:322-8.  Back to cited text no. 9
    
10.
Thibos LN, Hong X, Bradley A, Cheng X. Statistical variation of aberration structure and image quality in a normal population of healthy eyes. J Opt Soc Am A Opt Image Sci Vis 2002;19:2329-48.  Back to cited text no. 10
    
11.
Cheng X, Bradley A, Thibos LN. Predicting subjective judgment of best focus with objective image quality metrics. J Vis 2004;4:310-21.  Back to cited text no. 11
    
12.
Applegate RA, Marsack JD, Ramos R, Sarver EJ. Interaction between aberrations to improve or reduce visual performance. J Cataract Refract Surg 2003;29:1487-95.  Back to cited text no. 12
    
13.
Randle RJ. Responses of myopes to volitional control training of accommodation. Ophthalmic Physiol Opt 1988;8:333-40.  Back to cited text no. 13
    
14.
Zimmerman AB, Lust KL, Bullimore MA. Visual acuity and contrast sensitivity testing for sports vision. Eye Contact Lens 2011;37:153-9.  Back to cited text no. 14
    
15.
Balliet R, Clay A, Blood K. The training of visual acuity in myopia. J Am Optom Assoc 1982;53:719-24.  Back to cited text no. 15
    
16.
Garland DJ, Barry JR. Sport expertise: The cognitive advantage. Percept Mot Skills 1990;70:1299-314.  Back to cited text no. 16
    



 
 
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