SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "L773:0146 0404 OR L773:1552 5783 ;pers:(Unsbo Peter)"

Sökning: L773:0146 0404 OR L773:1552 5783 > Unsbo Peter

  • Resultat 1-10 av 10
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  •  
2.
  •  
3.
  •  
4.
  •  
5.
  • Rosén, Robert, et al. (författare)
  • Influence of Optical Defocus on Peripheral Vision
  • 2011
  • Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 52:1, s. 318-323
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE. Peripheral optical corrections are often thought to give few visual benefits beyond improved detection acuity. However, patients with central visual field loss seem to benefit from peripheral correction, and animal studies suggest a role for peripheral vision in the development of myopia. This study was conducted to bridge this gap by systematically studying the sensitivity to optical defocus in a wide range of peripheral visual tasks. METHODS. The spatial frequency threshold for detection and resolution in high and low contrast with stationary and drifting gratings were measured off-axis (20 nasal visual field) in five subjects with a peripheral optical correction that was varied systematically +/- 4 D. RESULTS. All visual tasks, except high-contrast resolution, were sensitive to optical defocus, particularly low-contrast resolution with an increase of up to 0.227 logMAR/D. The two myopic subjects exhibited a very low sensitivity to defocus by negative lenses for low-contrast tasks, whereas all subjects were equally affected by myopic defocus. Contrary to expectations, drifting gratings made little difference overall. CONCLUSIONS. Optical defocus as low as 1 D has a large impact on most peripheral visual tasks, with high-contrast resolution being the exception. Since the everyday visual scenery consists of objects at different contrast levels, it is understandable that persons with central visual field loss are helped by correction of peripheral refractive errors. The asymmetry in sensitivity to peripheral optical defocus in low-contrast tasks that was experienced by the myopic subjects in this study merits further investigation.
  •  
6.
  •  
7.
  • Rosén, Robert, et al. (författare)
  • Sign-Dependent Sensitivity to Peripheral Defocus for Myopes due to Aberrations
  • 2012
  • Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 53:11, s. 7176-7182
  • Tidskriftsartikel (refereegranskat)abstract
    • PURPOSE. Animal studies suggest that the periphery of the eye plays a major role in emmetropization. It is also known that human myopes tend to have relative peripheral hyperopia compared to the foveal refraction. This study investigated peripheral sensitivity to defocus in human subjects, specifically whether myopes are less sensitive to negative than to positive defocus. METHODS. Sensitivity to defocus (logMAR/D) in the 20 degrees nasal visual field was determined in 16 emmetropes (6 males and 10 females, mean spherical equivalent -0.03 +/- 0.13 D, age 30 +/- 6 10 years) and 16 myopes (3 males and 13 females, mean spherical equivalent -3.25 +/- 2 D, age 25 +/- 6 years) using the slope of through-focus low-contrast resolution (10%) acuity measurements. Peripheral wavefront measurements at the same angle were obtained from 13 of the myopes and 9 of the emmetropes, from which the objective depth of field was calculated by assessing the area under the modulation transfer function (MTF) with added defocus. The difference in depth of field between negative and positive defocus was taken as the asymmetry in depth of field. RESULTS. Myopes were significantly less sensitive to negative than to positive defocus (median difference in sensitivity 0.06 logMAR/D, P = 0.023). This was not the case for emmetropes (median difference -0.01 logMAR/D, P = 0.382). The difference in sensitivity between positive and negative defocus was significantly larger for myopes compared to emmetropes (P = 0.031). The correlation between this difference in sensitivity and objective asymmetry in depth of field due to aberrations was significant for the whole group (R-2 = 0.18, P 0.02) and stronger for myopes (R-2 = 0.8, P < 0.01). CONCLUSIONS. We have shown that myopes, in general, are less sensitive to negative than to positive defocus, which can be linked to their aberrations. This finding is consistent with a previously proposed model of eye growth that is driven by the difference between tangential and radial peripheral blur.
  •  
8.
  •  
9.
  •  
10.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 10

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy