68:
88:. Break point, recovery and blur are key aspects of this assessment. The break point occurs at the loss of BSV, recovery point when BSV is regained from break and blur point is at the loss of comfortable BSV. These stops can be subjectively indicated when the patient notices a double or blurred image. Both subjective and objective measurements can be considered however the examiner's objective observation is the gold standard.
52:(double vision). Relative fusional vergence is the maximum vergence movement enabling a patient to see a comfortable clear image and the limit is represented by the first point of blur. These motor fusion functions should fall within average values so that BSV can be comfortably achieved. Excessive stress on the
79:
bar in front of an eye. In a patient with BSV, a natural shift of the eye occurs. When measuring horizontal fusion ranges, base in prisms assess fusional divergence while base out prisms assess fusional convergence. The vertical fusional vergence amplitude can also be measured with base up and base
153:
bar in front of one of the patient's eyes with the prism placed “base in” to assess the fusional divergence amplitude. The divergence amplitude should be measured before convergence, as measuring the convergence amplitude first could contaminate the results of the divergence amplitude since
474:
Agarwal, A., Agarwal, A., Agarwal, S., Alio, J.L., Apple, D.J., Burrato, L. & Pandey, S.K. (2002). Textbook of
Ophthalmology: Basic Sciences, Optics and Refraction, Neuro-ophthalmology, Strabismus (1st ed.). Jaypee Brothers Medical Publishers (P)
192:
The results from this method of assessment rely on the patient's responses, and are therefore subjective. The assessment should also be performed objectively, in which the examiner observes the eye's movement behind the
533:
Codina, C.J. & Ludden, S. M. (2013). Is there an ideal speed for the prism fusion range?. The
British and Irish Orthoptic Journal, 10, 51-55. Retrieved from www.bioj.org/index.php/bioj/article/download/103/83
232:
Note: Some examiners may choose not to assess and/or record ‘recovery’. If recovery is being recorded, separate the ‘break’ and accompanying ‘recovery’ results with a forward slash i.e. “/”.
256:
There are two ways to record the PFR results, the first being the fusion range (break without recovery) and the other including break and recovery. Follow the examples below for guidance:
286:
Patient results should be compared to the normal values for prism fusional amplitudes to determine if the patient has any anomalies. Recovery should ideally be within 5Δ of break point.
241:
in front of the eye denoted by: base in “BI” or “-” for fusional divergence; base out “BO” or “+” for fusional convergence; base up “BU” or base down “BD” for vertical fusional vergence.
64:) or loss of control of ocular misalignments. Motor anomalies can be managed in various ways, however, in order to commence treatment, motor fusion testing such as the PFR is required.
146:
The patient, able to appreciate BSV, is asked to fixate on the accommodative target for the entirety of the assessment and to indicate when the target first becomes doubled.
80:
down prisms although the horizontal PFR is typically the main focus when testing. When performing the PFR, prism strengths are increased, placing greater demand on the
639:
71:
Equipment required to perform a Prism Fusion Range Test. From left to right: an accommodative fixation stick, a vertical prism bar, and a horizontal prism bar.
317:
Divergence excess - when divergence occurs in excess, therefore the eyes demonstrate a reduced ability to converge. Usually occurs with an exo-deviation.
177:
was appreciated is recorded as the break point. From the break point, the examiner slowly reduces the prismatic power until the patient regains BSV. The
314:
Divergence insufficiency- although rare and usually associated with a neurological condition, the PFR is able to detect a reduced divergence range.
595:
585:
659:
623:
518:
48:
and relative fusional vergences. Fusional vergence is the maximum vergence movement enabling BSV and the limit is at the point of
135:
bars (horizontal and vertical) and an accommodative fixation target such as a letter on a fixation stick for near, or a
491:
356:
304:
165:
of the smallest power, the examiner increases the prismatic power slowly, allowing a fusion response for each
33:
345:
139:
letter for distance. The patient should wear their refractive correction for the distance being tested.
119:
positive and negative relative fusional convergence by asking patient to report when blur is appreciated
209:
When recording the results obtained from the PFR, it is important to include the following in order:
455:
308:
551:
633:
397:
Objective measurements rely on examiner expertise and may be difficult for beginners to observe.
67:
619:
591:
514:
432:
377:
249:
45:
437:
391:
37:
442:
131:
The PFR is performed in bright lighting conditions at near (33 cm) or far (6m), using
495:
300:
If patient results do not reflect the normal values, they may have the following issues:
238:
226:
222:
194:
185:
178:
166:
162:
150:
132:
76:
653:
181:
value at which the patient's BSV is first restored is recorded as the recovery point.
136:
29:
104:
61:
387:
Convergence must be measured second to divergence or results will be contaminated.
508:
487:
Care of the
Patient with Accommodative and Vergence Dysfunction. Retrieved from
370:
32:
to assess motor fusion, specifically the extent to which a patient can maintain
400:
Subjective measurements require patient cooperation to attain reliable results.
422:
410:
352:
57:
488:
311:
difficulties, the fusional convergence range of these patients is reduced.
450:
427:
381:
245:
198:
174:
170:
155:
85:
81:
53:
49:
41:
614:
Kanski, Bowling, Nischal, & Pearson, J., B., K., & A. (2011).
332:
measures binocular functions and control of deviation simultaneously.
197:, anticipating the break point at which the eye can no longer make a
507:
Wright, Kenneth W.; Spiegel, Peter H.; Thompson, Lisa (2006-04-19).
122:
progress of a patient undergoing management for ocular misalignments
219:
distance the test was performed at i.e. far “(6m)” or near “(1/3m)”
60:, which generally result from decompensation of latent deviations (
28:
is a clinical eye test performed by orthoptists, optometrists, and
142:
The following method relates to assessment of the horizontal PFR.
56:
system or inability to converge or diverge adequately can lead to
225:
power at which the patient ‘breaks’ and ‘recovers’ i.e. the
188:
bar placed with its base out to assess fusional convergence.
184:
The above steps are repeated for the same eye, but with the
44:
demands. Motor fusion is largely accounted to amplitudes of
84:
system, eventually resulting in a break point accompanying
355:
exercises required to manage fusional inadequacies i.e.
574:
Diagnosis and
Management of Ocular Motility Disorders .
229:
power number followed by its measuring unit symbol “Δ”
216:
with optical correction “cc” or without correction “sc”
584:
Howard, Ian P.; Rogers, Brian J. (24 February 2012).
116:
vertical amplitude with base up and base down prisms
169:, until the patient can no longer fuse and reports
341:Can provide subjective and objective measurements.
244:what the patient sees when they ‘break’; i.e. “c
587:Perceiving in Depth, Volume 1: Basic Mechanisms
338:measures horizontal and vertical fusion ranges.
103:strength of binocular functions (control) of a
96:This test is designed to assess the following:
552:"Investigative techniques in binocular vision"
510:Handbook of Pediatric Strabismus and Amblyopia
8:
638:: CS1 maint: multiple names: authors list (
483:
481:
282:PFR cc (1/3m) -16/14Δ → +45/40Δ c diplopia
110:fusional convergence with a base out prism
570:
568:
566:
564:
513:. Springer Science & Business Media.
269:PFR sc (1/3m) 16Δ BI → 45Δ BO c diplopia
154:convergence movements induce significant
489:https://www.aoa.org/documents/CPG-18.pdf
113:fusional divergence with a base in prism
66:
467:
390:Can only be performed on patients with
631:
376:Can not be performed on patients with
279:PFR sc (6m) -8/6Δ → +20/15Δ c diplopia
213:name of the test performed; i.e.“PFR”
7:
609:
607:
545:
543:
541:
539:
107:to determine if it is decompensating
205:Recording and interpreting outcomes
344:Can be performed on patients with
14:
173:. The prism power value at which
618:. Edinburgh: Elsevier/Saunders.
40:) in the presence of increasing
380:as patients can not appreciate
346:abnormal retinal correspondence
293:Distance (6m): 5-7Δ BI → 15Δ BO
290:Near (1/3m): 15Δ BI → 35-40Δ BO
1:
411:Prism Fusion Range test video
100:the limits of a patient's BSV
322:Advantages and disadvantages
590:. Oxford University Press.
335:Minimal equipment required.
75:The PFR involves placing a
26:fusional vergence amplitude
676:
307:- usually associated with
266:PFR cc (6m) 8Δ BI → 20Δ BO
201:movement to maintain BSV.
357:convergence insufficiency
305:Convergence insufficiency
237:relevant position of the
660:Diagnostic ophthalmology
149:The examiner places the
296:Vertical: 3Δ BU → 3Δ BD
34:binocular single vision
616:Clinical Ophthalmology
72:
127:Methods of assessment
70:
550:Weddell, L. (2010).
58:asthenopic symptoms
494:2016-03-03 at the
161:Starting with the
92:Indications of use
73:
46:fusional vergences
18:prism fusion range
597:978-0-19-976414-3
274:Break + recovery:
667:
644:
643:
637:
629:
611:
602:
601:
581:
575:
572:
559:
558:
556:
547:
534:
531:
525:
524:
504:
498:
485:
476:
472:
438:Binocular Vision
369:Can not measure
30:ophthalmologists
675:
674:
670:
669:
668:
666:
665:
664:
650:
649:
648:
647:
630:
626:
613:
612:
605:
598:
583:
582:
578:
573:
562:
554:
549:
548:
537:
532:
528:
521:
506:
505:
501:
496:Wayback Machine
486:
479:
473:
469:
464:
419:
407:
366:
351:Determines the
329:
324:
207:
129:
94:
12:
11:
5:
673:
671:
663:
662:
652:
651:
646:
645:
624:
603:
596:
576:
560:
535:
526:
519:
499:
477:
466:
465:
463:
460:
459:
458:
453:
448:
445:
440:
435:
430:
425:
418:
415:
414:
413:
406:
405:External links
403:
402:
401:
398:
395:
394:to start with.
388:
385:
374:
365:
362:
361:
360:
349:
342:
339:
336:
333:
328:
325:
323:
320:
319:
318:
315:
312:
298:
297:
294:
291:
284:
283:
280:
271:
270:
267:
254:
253:
242:
235:
234:
233:
220:
217:
214:
206:
203:
190:
189:
182:
159:
147:
128:
125:
124:
123:
120:
117:
114:
111:
108:
101:
93:
90:
13:
10:
9:
6:
4:
3:
2:
672:
661:
658:
657:
655:
641:
635:
627:
625:9780702055720
621:
617:
610:
608:
604:
599:
593:
589:
588:
580:
577:
571:
569:
567:
565:
561:
553:
546:
544:
542:
540:
536:
530:
527:
522:
520:9780387279244
516:
512:
511:
503:
500:
497:
493:
490:
484:
482:
478:
471:
468:
461:
457:
456:Accommodation
454:
452:
449:
446:
444:
441:
439:
436:
434:
431:
429:
426:
424:
421:
420:
416:
412:
409:
408:
404:
399:
396:
393:
389:
386:
383:
379:
375:
372:
368:
367:
364:Disadvantages
363:
358:
354:
350:
347:
343:
340:
337:
334:
331:
330:
326:
321:
316:
313:
310:
309:accommodative
306:
303:
302:
301:
295:
292:
289:
288:
287:
281:
278:
277:
276:
275:
268:
265:
264:
263:
261:
257:
251:
247:
243:
240:
236:
231:
230:
228:
224:
221:
218:
215:
212:
211:
210:
204:
202:
200:
196:
187:
183:
180:
176:
172:
168:
164:
160:
157:
152:
148:
145:
144:
143:
140:
138:
137:Snellen Chart
134:
126:
121:
118:
115:
112:
109:
106:
102:
99:
98:
97:
91:
89:
87:
83:
78:
69:
65:
63:
59:
55:
51:
47:
43:
39:
35:
31:
27:
23:
19:
615:
586:
579:
529:
509:
502:
470:
371:cyclotorsion
299:
285:
273:
272:
260:Fusion range
259:
258:
255:
208:
191:
141:
130:
105:heterophoria
95:
74:
62:heterophoria
25:
21:
17:
15:
433:Suppression
378:suppression
250:suppression
158:adaptation.
462:References
423:Strabismus
327:Advantages
634:cite book
353:orthoptic
654:Category
492:Archived
451:Vergence
428:Diplopia
417:See also
382:diplopia
248:” or “c
246:diplopia
199:vergence
175:diplopia
171:diplopia
156:vergence
86:diplopia
82:vergence
54:vergence
50:diplopia
42:vergence
622:
594:
517:
447:20 PRT
555:(PDF)
443:4 PRT
239:prism
227:prism
223:prism
195:prism
186:prism
179:prism
167:prism
163:prism
151:prism
133:prism
77:prism
24:) or
640:link
620:ISBN
592:ISBN
515:ISBN
16:The
475:Ltd
392:BSV
38:BSV
22:PFR
656::
636:}}
632:{{
606:^
563:^
538:^
480:^
262::
642:)
628:.
600:.
557:.
523:.
384:.
373:.
359:.
348:.
252:”
36:(
20:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
