title: Peripheral refraction in myopia corrected with spectacles versus contact lenses.
abstract: OBJECTIVE
  Previous studies suggest that the refractive status of the peripheral retina can influence the development and progression of myopia. Our aim was to compare peripheral refractions in the same cohort of human eyes corrected with spectacle lenses vs soft contact lenses.
  
  
  METHODS
  Ten young adults with moderate to high myopia (-5.00 D to -8.00 D) were investigated. Open-field autorefraction was used to measure on- and off-axis refractions with the eyes in primary gaze, when uncorrected, and when corrected with spectacles and contact lenses. Measures were made every 5° out to 30° horizontally in nasal and temporal retina and analysed as power vectors (M, J(0) , and J(45)). Partial coherence interferometry measures of eye size were also made on-axis and off-axis at 10º and 20º in nasal and temporal retina.
  
  
  RESULTS
  Subjects (mean age 24; range 19-29 years) had an average on-axis mean-sphere refraction of -6.33 ± 0.31 D (mean ± 1 S.E.) and an average axial eye length of 25.99 ± 0.20 mm. The average relative peripheral refraction (RPR) for all subjects across all eccentricities was hyperopic when uncorrected (+0.90 ± 0.14 D) and also when corrected with spectacles (+1.01 ± 0.13 D) but changed to a myopic RPR when corrected with contact lenses (-1.84 ± 0.61 D). There was a highly significant effect of correction on peripheral refraction (p < 0.0001). Peripheral J(0) astigmatism also became significantly more negative (less with-the-rule) on correction with contact lenses (p = 0.015), whereas J(45) astigmatism remained unchanged. On- and off- axis eye length measures indicated a relatively prolate eye shape.
  
  
  CONCLUSIONS
  Correcting the on-axis refractive error in moderate to high myopia with conventional spherical spectacle lenses results in hyperopic defocus in the peripheral retina. Correcting the same eyes with conventional spherical soft contact lenses results in significant myopic defocus in the peripheral retina. These results corroborate the general findings of earlier studies and the predictions of optical modelling by others. If the refractive status of the peripheral retina does influence myopia progression, then these results suggest that myopia progression should be slower with conventional contact lens wear than with conventional spectacle wear. However, previous studies comparing myopia progression with conventional spectacles and conventional contact lenses have reported no such difference.
authors.affiliation: Department of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand. s.backhouse@auckland.ac.nz
authors.forename: Simon
authors.initials: S
authors.lastname: Backhouse
authors.forename: Stephanie
authors.initials: S
authors.lastname: Fox
authors.forename: Basma
authors.initials: B
authors.lastname: Ibrahim
authors.forename: John R
authors.initials: JR
authors.lastname: Phillips
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D003261:Contact Lenses; D005123:Eye / Q000473:pathology; D005139:Eyeglasses; D006801:Humans; D009216:Myopia / Q000473:pathology / Q000503:physiopathology* / Q000628:therapy; D012029:Refraction, Ocular / Q000502:physiology*; D012160:Retina / Q000473:pathology / Q000503:physiopathology; D055815:Young Adult