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Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs
Dissertation (MMedVet)--University of Pretoria, 2011.
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University of Pretoria
2013
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| _version_ | 1867613643184537600 |
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| access_status_str | Open Access |
| author2 | Goodhead, Antony Denzil |
| author_browse | Goodhead, Antony Denzil |
| author_facet | Goodhead, Antony Denzil |
| collection | Thesis |
| dc_rights_str_mv | © 2011, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria |
| description | Dissertation (MMedVet)--University of Pretoria, 2011. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/24949 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:39:24.464Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/24949 Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs Goodhead, Antony Denzil Roux, Polla dramilan@gmail.com Sivagurunathan, Amilan Refractive state Handheld autorefractors Manual streak retinoscopes Guide dogs UCTD South Africa Dissertation (MMedVet)--University of Pretoria, 2011. In medical ophthalmology, refractive studies have become an integral part of a complete ophthalmic examination and second only to a slit-lamp biomicroscopic examination in determining visual function and ability. This study shows that the same ideology applies to refractive studies on dogs. The refraction technique has evolved in process, with refinement of the technology and methods used; with the development of handheld autorefractors utilised in paediatric refraction. Fifty guide dogs completed this study however five of the dogs were subsequently excluded and replaced because of poor compliance. Forty six of the dogs were Labrador Retrievers; one was a Golden Retriever, one a Great Dane cross, one a Labrador cross and one a cross breed. The median sample age was 17months with an interquartile range (IQR) of13 to 34months. We validated the agreement in refractive error measurement between the Welch Allyn ™ "SureSight" (WASS) autorefractor to the traditional Welch Allyn ™ handheld streak retinoscope (SR) by two experienced investigators, due to previous studies showing variability in measurement for both instruments. The refractive state for 60°/o of the guide dogs sampled at South African Guide Dogs Association (SAGDA) were emmetropic (-0.5 to +0.5D), 34% were hypermetropic (>+0.5D) with 6% myopic (<-0.5D). For agreement between the instruments, a wide range of differences using mean spherical equivalence (MSE) was observed between the 95% limits of agreement (-1.911 D to 1.698D). On average,measurements with the WASS were slightly lower compared to the SR (mean difference = 0.013). Both instruments showed a better average agreement in determining emmetropia with a tendency to underestimate refractive errors for greater negative and positive diopters. The WASS showed better agreement with the SR for refractive error measurement with higher reliability scale values (8 and above). Clinical astigmatism (>- 0.50 cylinder) was detected more readily on the WASS (37 dogs) than on the SR (9 dogs). Between investigators the MSE measurements differed significantly (P = 0.02), with the average agreement on the SR slightly better than the WASS. Overall, the handheld manual streak retinoscope remains the more practical, cost effective and efficient instrument for objective refraction in dogs. We can also conclude, that current subjective criteriae utilised in the selection of guide dogs at SAGA can be further improved by including objective methods of refraction. Copyright Companion Animal Clinical Studies unrestricted 2013-09-06T18:55:26Z 2013-01-10 2013-09-06T18:55:26Z 2012-04-13 2011 2012-05-24 Dissertation Sivagurunathan, A 2011, Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs, MMedVet dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/24949 > E12/4/307/gm http://hdl.handle.net/2263/24949 http://upetd.up.ac.za/thesis/available/etd-05242012-150351/ © 2011, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria application/pdf University of Pretoria |
| spellingShingle | Refractive state Handheld autorefractors Manual streak retinoscopes Guide dogs UCTD South Africa Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title | Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title_full | Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title_fullStr | Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title_full_unstemmed | Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title_short | Measurement of the refractive state using streak retinoscopy and the "Sure Sight™" autorefractor in dogs |
| title_sort | measurement of the refractive state using streak retinoscopy and the sure sight™ autorefractor in dogs |
| topic | Refractive state Handheld autorefractors Manual streak retinoscopes Guide dogs UCTD South Africa |
| url | http://hdl.handle.net/2263/24949 http://upetd.up.ac.za/thesis/available/etd-05242012-150351/ |