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16 Cards in this Set
- Front
- Back
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two main uses of prisms?
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therapeutic
diagnostic |
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DIAGNOSTIC USE OF PRISMS?
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1. quantitating strabismus - measurements
2. PAT - correction of deviation determines if patient has binocular potential - obtain maximum amount of deviation 3. PRE-Op: correct deviation to check if patient will have post op diplopia 4. POST-Op: eliminate post op diplopia especially vertical 5. determine the relevance of small horizontal/vertical deviations 6. monitor stability of deviation - imp in pts waiting for Sx 7. undiagnosed head postures 8. treatment of diplopia |
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What is prism adaptation tst (PAT)?
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pre-operative usage of prism to determine surgical target aNGLE and estimate fusional potential
* uncovers latent deviation * determins fusional potential |
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Briefly summarize the PAT -
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- distance eso neutralized with fresnels
- pts followed weekly and prisms adjusted appropriately until labeled as "responders" or "non" - RESPONDER: stable dev (8 pd or less) with W4D; Sx done on amt of ET present AFTER PAT - NON RESP: with prisms, deviation builds greater than 60 pd without fusion prisms : XT distance, ET near. thrn Sx is just done on original angle |
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What is the goal of PAT?
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orthotropic of s;lightly XT
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THERAPEUIC USE OF PRISM?
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1. alleviate diplopia (restore bsv) - COMFORTABLE, HAPPY, AND FUSING
2. alleviate asthenopia - control of deviation if symptomatic usually just correct amount of dev for pt to maintain comfortable bsv 3. nystagmus - BO prism to stimulate convergence or place prisms to move images to pts null zone 4. orthoptic - increase conv and div amplitudes 5. amblyopia treatment - breaks up eccentric fixation 6. low vision pts - move image to part of the retina that is not damaged 7. field defects - move image away from field defect |
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two types of prisms?
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fresnel and incorporated (ground or decentered)
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What are some advantages of using fresnel prisms?>
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light weight
temporary cheap variety of strength availability minimal distortion can be easily applied in office more acceptable appearance |
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disadvantages of fresnels?
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higher powers are blurry
not all strengths avail stains over time, becmes not sticky and need to be replaced often lost or slide out of alignment ONE LINE LOST PER 10 PD OF FRESNEL |
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why is it not generally accepted to put prisms over both eyes?
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blur
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what is the main goal of PAT>
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BSV
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what considerations must be made for pat?
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- binocular status
- size of deviation - fresnels go up to 50 pd but no therapy for large devations - type of dev - occupation req - comitancy - age - pts GH |
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when is fresnel prism therapy best done? (size) who is it used most on?
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20 pd or less
adults to alleviate diplopia |
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why is pre-op PAT important?
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uncover the REAL deviation - see if they will be able to fuse post operatively
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define prism adaptaion?
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pre=operative wearing of fresnel prism to offset deviation angle, prism power is adjusted over time if needed until fusion is achieved or demonstrated that it cannot be achieved
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purpose of pat?
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1. uncover maximum strabismic angle of dev
2. determine fusional potential |
