Is there an ideal speed for the prism fusion range?
Aim: To evaluate the effect of speed of prism increase on prism fusion range (PFR) and to determine a recommended speed for performing PFR. Methods: Twenty-six participants (18–32 years) with binocular single vision (BSV) and minimum TNO stereo-acuity of 60 seconds of arc underwent PFR assessment...
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| Format: | Article |
| Language: | English |
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White Rose University Press
2012-08-01
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| Series: | British and Irish Orthoptic Journal |
| Subjects: | |
| Online Access: | https://www.bioj-online.com/articles/73 |
| _version_ | 1818446968121196544 |
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| author | Siobha N M. Ludden Charlotte J. Codina |
| author_facet | Siobha N M. Ludden Charlotte J. Codina |
| author_sort | Siobha N M. Ludden |
| collection | DOAJ |
| description | Aim: To evaluate the effect of speed of prism increase on prism fusion range (PFR) and to determine a recommended speed for performing PFR. Methods: Twenty-six participants (18–32 years) with binocular single vision (BSV) and minimum TNO stereo-acuity of 60 seconds of arc underwent PFR assessment at 1 3 m and 6 m. Ocular dominance was assessed. Three rates of prism strength increase were uniformly employed: prism increased every one second (1 s), every two seconds (2 s) and every three seconds (3 s) (in random order). Base in (BI) was assessed before base out (BO). A 10-minute period of binocular viewing was given to participants between each assessment speed. Break point of fusion was recorded. The participant’s preferred assessment speed was recorded post testing. Results: The total PFR was significantly extended by increasing the viewing time through each prism (F2,50 = 15.977, p < 0.0001). Near PFR was extended significantly more than distance PFR with increased viewing time (Fsub2,50 = 4.074, p = 0.023). The BO range was significantly more affected by testing speed than the BI range (F2,50 = 9.900, p = 0.0002). Ocular dominance did not have a significant effect on PFR ( p =0.75). 69% of participants favoured the two second per prism assessment speed. Conclusions: In participants with normal BSV, the PFR can be significantly extended when a longer target viewing time is given through each prism. This highlights the need for a uniform assessment speed. For reasons of participant comfort and clinical time efficiency, increasing the prism strength after 2 seconds fixation per prism is recommended for the clinical assessment of the PFR. |
| first_indexed | 2024-12-14T19:56:09Z |
| format | Article |
| id | doaj.art-b782ea2423c0445198596017e67456b3 |
| institution | Directory Open Access Journal |
| issn | 2516-3590 |
| language | English |
| last_indexed | 2024-12-14T19:56:09Z |
| publishDate | 2012-08-01 |
| publisher | White Rose University Press |
| record_format | Article |
| series | British and Irish Orthoptic Journal |
| spelling | doaj.art-b782ea2423c0445198596017e67456b32022-12-21T22:49:18ZengWhite Rose University PressBritish and Irish Orthoptic Journal2516-35902012-08-0110515510.22599/bioj.7372Is there an ideal speed for the prism fusion range?Siobha N M. Ludden0Charlotte J. Codina1Academic Unit of Ophthalmology and Orthoptics, University of Sheffield, SheffieldAcademic Unit of Ophthalmology and Orthoptics, University of Sheffield, SheffieldAim: To evaluate the effect of speed of prism increase on prism fusion range (PFR) and to determine a recommended speed for performing PFR. Methods: Twenty-six participants (18–32 years) with binocular single vision (BSV) and minimum TNO stereo-acuity of 60 seconds of arc underwent PFR assessment at 1 3 m and 6 m. Ocular dominance was assessed. Three rates of prism strength increase were uniformly employed: prism increased every one second (1 s), every two seconds (2 s) and every three seconds (3 s) (in random order). Base in (BI) was assessed before base out (BO). A 10-minute period of binocular viewing was given to participants between each assessment speed. Break point of fusion was recorded. The participant’s preferred assessment speed was recorded post testing. Results: The total PFR was significantly extended by increasing the viewing time through each prism (F2,50 = 15.977, p < 0.0001). Near PFR was extended significantly more than distance PFR with increased viewing time (Fsub2,50 = 4.074, p = 0.023). The BO range was significantly more affected by testing speed than the BI range (F2,50 = 9.900, p = 0.0002). Ocular dominance did not have a significant effect on PFR ( p =0.75). 69% of participants favoured the two second per prism assessment speed. Conclusions: In participants with normal BSV, the PFR can be significantly extended when a longer target viewing time is given through each prism. This highlights the need for a uniform assessment speed. For reasons of participant comfort and clinical time efficiency, increasing the prism strength after 2 seconds fixation per prism is recommended for the clinical assessment of the PFR.https://www.bioj-online.com/articles/73Assessment speedPrism fusion rangeVergence adaptation |
| spellingShingle | Siobha N M. Ludden Charlotte J. Codina Is there an ideal speed for the prism fusion range? British and Irish Orthoptic Journal Assessment speed Prism fusion range Vergence adaptation |
| title | Is there an ideal speed for the prism fusion range? |
| title_full | Is there an ideal speed for the prism fusion range? |
| title_fullStr | Is there an ideal speed for the prism fusion range? |
| title_full_unstemmed | Is there an ideal speed for the prism fusion range? |
| title_short | Is there an ideal speed for the prism fusion range? |
| title_sort | is there an ideal speed for the prism fusion range |
| topic | Assessment speed Prism fusion range Vergence adaptation |
| url | https://www.bioj-online.com/articles/73 |
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