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Peripheral refraction patterns out to large field angles.
MedLine Citation:
PMID:  23353991     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
PURPOSE: To investigate hyperopic shifts and the oblique (or 45-degree/135-degree) component of astigmatism at large angles in the horizontal visual field using the Hartmann-Shack technique.
METHODS: The adult participants consisted of 6 hypermetropes, 13 emmetropes and 11 myopes. Measurements were made with a modified COAS-HD Hartmann-Shack aberrometer across ±60 degrees along the horizontal visual field in 5-degree steps. Eyes were dilated with 1% cyclopentolate. Peripheral refraction was estimated as mean spherical (or spherical equivalent) refraction, with/against the rule of astigmatism and oblique astigmatism components, and as horizontal and vertical refraction components based on 3-mm major diameter elliptical pupils.
RESULTS: Thirty percent of eyes showed a pattern that was a combination of type IV and type I patterns of Rempt et al. (Rempt F, Hoogerheide J, Hoogenboom WP. Peripheral retinoscopy and the skiagram. Ophthalmologica 1971;162:1-10), which shows the characteristics of type IV (relative hypermetropia along the vertical meridian and relative myopia along the horizontal meridian) out to an angle of between 40 and 50 degrees before behaving like type I (both meridians show relative hypermetropia). We classified this pattern as type IV/I. Seven of 13 emmetropes had this pattern. As a group, there was no significant variation of the oblique component of astigmatism with angle, but about one-half of the eyes showed significant positive slopes (more positive or less negative values in the nasal field than in the temporal field) and one-fourth showed significant negative slopes.
CONCLUSIONS: It is often considered that a pattern of relative peripheral hypermetropia predisposes to the development of myopia. In this context, the finding of a considerable portion of emmetropes with the IV/I pattern suggests that it is unlikely that refraction at visual field angles beyond 40 degrees from fixation contributes to myopia development.
Authors:
Ankit Mathur; David A Atchison
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Optometry and vision science : official publication of the American Academy of Optometry     Volume:  90     ISSN:  1538-9235     ISO Abbreviation:  Optom Vis Sci     Publication Date:  2013 Feb 
Date Detail:
Created Date:  2013-01-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8904931     Medline TA:  Optom Vis Sci     Country:  United States    
Other Details:
Languages:  eng     Pagination:  140-7     Citation Subset:  IM    
Affiliation:
*PhD, FAAO †PhD, DSc, FAAO School of Optometry and Institute of Health & Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland, Australia.
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