Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Accommodation
Procedures 1 Spring 2010 Dr.Miller
| Question | Answer |
|---|---|
| Define "functional evaluation" | the evaluation of the accommodative and occulomotor systems. |
| Define accommodation | the adjustment of the dioptric power of the eye beyond its static resting power due to a change in the shape of the crystalline lens |
| What is the stimulus for accommodation | An out of focus retinal image, or retinal blur |
| Describe the processes involved during an increase in accommodation | PSNS is actvtd rsltng in near triad 1.accmmdtn incrses, cillry mscles cntract, zonules are slack,lens incrs in crvtr antrly, lens becomes thicker, equtrl diam of lens decrses 2.miosis 3.convergence |
| Describe the processes involved during an decrease in accommodation | Sympathetic NS control 1.cmuscles relax, zonules taught, lens shape is relatively flat 2.mydriasis 3.divergence |
| What is Tonic/Resting state accommodation? | 1.occurs in absnce of accmmdtve stimls 2.eye is focused at 80cm -this makes emmtrpc eye artfclly myopic w/o an accmmdtv stmls -due to a balnce b/t parasymp&symp innrvtn of cmuscle creating some sort of autonmc innervational eqbm |
| What is the induced refractive error of an emmetrope staring out into a clear sky? | An emmetrope will become a 1.25D myope due to tonic accommodation at -80cm |
| Describe the process of accommodation for looking at a distant stimulus (starting from the resting state) | Relaxation must occur! 1.SympNS repnds to blur 2.cillry mscl rlxes&zonules tightn,lens is flttnd&thind to a more unaccmmdtd form 3.this results in theoretically no accmmdtn at patient's Far point |
| Give two definitions for "far point" | 1.The farthest point for which the eye can form a sharp image on the retina 2.the farthest pint in space conjugate to the retina (fovea) |
| Describe the process of accommodation for looking at a near stimulus (starting from the resting state) | Requires increase in accmmdtn 1.occurs due to PSNS innrvtn 2.cillmuscl cntrcts, zonules rlax, lens assumes preferred spherical shape 3.this reslts in maximal accmmdtn at patient's near point |
| Give two definition for "near point" | 1.the nearest point for which the eye can form a sharp image on the retina 2.the nearest point in space conjugate with the retina when exerting maximal accmmdtve effort |
| How are object distances measured in testing? | From the spectacle plane (13mm from conrneal apex) |
| In what three ways can accommodation be stimulated? | 1.By placing an object at a distance closer than infinity (clinically, closer than 6m) 2.Using minus lenses 3.Using a combo of distance and minus lenses |
| What is a haploscope? | An instrument used to measure accommmodative responce |
| Do we measure accommodative responce? | Accommodative response testing not efficient clinically and reserved for research. Accommodative response is described by dioptric accommodative stimulus which is much more easily determined clinically. |
| What is the amplitude of accommodation? | Also called accommodative ampltd or focusing power: 1.Maximum amnt of accmmdtve pwr an eye can exert MEASURED IN DIOPTERS 2.AmpOAccom declines from 14D at 10 years old to about 0.50D at age 70 |
| What is the facility of accommodation? | Also called accommodative facility or focusing flexiblty: 1.ability of eye to quickly and accrtly shift accmmdtve postures 2.requires stimlting then relaxing accommdtive system |
| What is the lag of accommodation? | Also called accmmdtve lag, accmmdtve posture, accuracy of focusing 1.dstnce(diopters) b/t accmdtiv stimulus and accmmdtve respnse 2.it is normal lag to be present, or for the accommodative responce to be less than the accommodative stimulus |
| * How can the accommodative response be less than the accommodative stimuls and a clear retinal image be maintained? | Changes in depth of focus (of eye) or depth of field (of object space) accnt for presence of accmmdtv lag w/clear ret img: 1.depth of focus (of eyes) changes with changes inversly pupil size 2.depth of focus increases with increasing object size |
| What is the range of accommodation? | Also called accommdtv rng or rng of clear vis: 1.linear dstnc (cm) ovr whch accmdtive pwr allws for mntncne of clear vis 2.dstnce b/t NP & FP 3.part of range will be vrtual for hyperope |
| Which patients undergo accommodative testing & how will the results be effected if there is existing uncorrected refractive error? | accmdtve testing is done on patnts who have actve accommdtn(not presbyopes)&will yeild innacrt findings if the refractive error is not maximally corrected prior to testing |
| What are the five areas of accommodative functioning that are evaluated clinically? | 1.amplitude-tests for max focusng pwr 2.facility-tests for focusng flxblty 3.lag-tests for focsing respnse and balance 4.sustning abilty of accom-tsts for endrnce of focusng systm 5.consistency of accmmdtn-tests for consistncy of focusing response |
| What are the four methods for evaluating amplitude of accommodation? | 1.Hoffstetter's Formulas 2.Donder's Age reference tables 3.Pushup test 4.Minus lens to blur test |
| What is the Hoffstetter Formula? | A way to calculate expctd amp of accmdtn based on age. 1)amplitude decreases with age 2)Average expected amplitude of accmmdtn= 18.5 - 0.30(age) |
| What are two methods to estimate amplitude of accommodation based only on age? | 1.Hoffstetter's formula 2.Donder's age referenced table |
| What stimulus for accommodation does the pushup test use? | Distance |
| Why does the pushup test commonly yield larger measurements of Amplitude of accommdtn? | 1)Allowing the patient to hold the near pt target enhances feeling of proximity(kinesthetic sense) 2.object is held at reading level, not on axis |
| What is being assessed when using the pushup test monocularly? binocularly? | 1.Monocularly just the accommodation is being assessed 2.When doing pushup OU, the accommodation as well as the binocular system is being evaluated (binocular findings for amplitude are usually greater by .50D) |
| Under which conditions would you do the pushup test monocularly? | If amplitude is reduced binocularly or if diplopia occurs, otherwise, test is only done binocularly. |
| At what point during an examination is the pushup test done? | Usually done prior to the refractive sequence outside of phoropt w/ habitual& OU. If patnt has reduced VA it is done behind phoropt as part of post refrctn phorometry sequence. |
| What are the lighting conditions for the pushup test? | Full room lighting and extra overhead directed towards near target to maxmze contrast(but not create glare). Extra light also causes miosis which increases depth of field, decrses blur and increases ampltd of accmmdtn. |
| Why must the same line of letters be used during the pushup test when comparing OD, OS, and OU results? | Because as the target is moved closer, the vis angle increases & the angular size of the letters increases. |
| What is the stopping point for the Pushup test? | When the stick touches the patient's nose or when the letter become and remain blurry (point of sustained blur) |
| What happens if, during the pushup test, the stick is moved to quickly? | The amplitude of accommdtn measured will be lower |
| How is the amplitude of accommodation measured during the pushup test? | Stop position (position of sustained blur) is measured FROM THE SPECTACLE PLANE w/ PDruler. This is CONVERTED TO DIOPTERS and rounded off to the nearest quarter. |
| What is the stimulus for accommodation during the minus lens to blur test? | Distance and minus lenses cause blur |
| Why does the minus lens to blur test yield a reduced amplitude finding compared to the pushup test? How reduced are we talkin' here? | 1.anglr lttr size decrses w/ - lenses (minification factr) 2.no kinsethetic factr as trgt is statnry 3.target percvd as getting farther away (proximity factor in reverse) 4.results are 2D less than pushup test |
| What is the general procedure for the Minus lens to blur test? | SEE PAGE 10 of 17 in notes. 250 character limit for cards =( |
| What is the fixation target for the minus lens to blur test? | The pushup stick mounted on the near rod of the phoropter, one or two lines above BVA. |
| What is the end point for the minus lens to blur test? | When the patient can no longer "clear" the letters (first sustained blur) |
| What measurement is taken to calculate amplitude of accommodation when doing the minus lens to blur test? | The patient must accommodate past each -.25DS added. The doc must count the number of minus added at the endpoint & must also factor in the extra (2.5D) due to the near stim of 40cm |
| What are the two methods for testing the faculty of accommodation/ focusing flexibility | *Think going near to far 1.Lens Flipper Test 2.Near Far test |
| What is the stimulus for accommodation for the Flipper test? | *Flipper test measures FACILITY Minus lenses & distance induce accomm by causing blur, Plus lenses are used to relax accommodation |
| During what stage of an examination is the flipper test performed? | Patient is tested OU w/ habitual prior to refractive sequence. If the patient has reduced VA, done using trial frame as part of post refrctn functional testing |
| What is being evaluated when the flipper test is done monocularly? When done OU? | Monocular just measures accommodative facility. Binocular measures accommodatn as well as binocularity. |
| When would one perform the flipper test monocularly? | Only if reduced findings or diplopia during binocular testing |
| What is the general procedure for the flipper test? | SEE P 12 of 17 of notes |
| What is considered to be a "full cycle" for the Lens Flipper test? | One round of Plus then minus. |
| what is the expected normal for the lens flipper test? | 6 full cycles in 30 seconds or less (recorded as 6/30). If 6 cycles are completed in under 30s the denominator is the time of completion (ie 6/20 for 20s) NOTE:power of flippers used should also be indicated |
| How can one test the magnitude of accommodative infacility during the lens flipper test? | Flippers of a magnitude less than 2D can be used |
| What is the stimulus for accommodation in the near-far test? | Distance is used to cause blur (near target) and distance (the far target) is used to relax accommodation |
| Why is the lens flipper test the test of choice for clinical evaluation for facility of accommodation? | Most exam rooms are not long enough to completely facilitate relaxed accommodation at far that would be required during the near-far test. |
| During what portion of an exam is the near-far test administered? | Binocularly w/ habitual prior to refractv sequence. If reduced VA w/ habitual, done as part of post refrctv functional testing using a trial frame. |
| What is the general procedure for the Near-far test | See page 13 of 17 of notes |
| Where is the near target held during the near-far test? | At 2/3 distance of the patients amplitude of accommodation. |
| What is one "full cycle" for the near far test | Far-near-far |
| What is the expected finding for the near far test? | 10 or more cycles in 30 seconds and no diplopia. |
| What is recorded if, during the near far test, the patient lags on there response at near? If the patient lags on there response at distance? | 1.Decayed at near (indicates inadequate/slow accommodation) 2.Decayed at at far (indicates inability for accommodative system to relax properly) |
| What is recorded if, during the flipper test, the patient lags on there response when plus is presented? When minus is presented? | 1.Can't clear plus (indicates accommdtve system not relaxing properly) 2. Can't clear minus (indicates inadequate accommodative response) |
| What is the most common method used to evaluate lag of accommodation? | Dynamic Retinoscopy |
| Name three types of dynamic retinoscopy | 1. Nott Ret 2. Monocular estimation method ret. (MEM) 3. Bell Ret |
| What type of accommodative stimulus is used in the 3 types of retinoscopy? | 1. Nott Ret- Fixed accommodative stimulus 2. MEM Ret- Fixed accommodative stimulus 3. Bell Ret- Varied accomodative stimulus |
| When is Nott Ret done? | Done as part of post-refraction functional testing using BVA. |
| What is the stimulus for accommodation during Nott Ret? | Distance (near target) used to create blur. |
| What is the normal expected finding for lag of accommodation using Nott Ret? What is indicated if findings fall outside of this range? | 1.Lag should be +.50D and symmetric 2.Values>.50 indicate a large lag/ lazy accmmdtv response 3.Values<.50 indicate a a low, zero or negative lage and a "tight"accommodative response 4.Asymmetric findings indicate a health or refractive etiology |
| What is the general procedure for Nott Ret? | 1.monocularly w/ both eyes open, BVA in phoropter 2.near PD in phoropter 3.stick mounted on near rod for best on axis viewing by doc See pg 14 of 17 for more |
| During which portion of the exam is Nott Ret done? | Post refraction and at the conclusion of phorometry tests as part of the post-refractional functional testing |
| What is done if, during Nott Ret, With motion is initially observed? | This means patient has lag of accmdtn & plane of focus is behind doc. Doc moves bck till neutrlty & the distance moved is recorded in a positive dioptric value. |
| What is done if, during Nott Ret, Neutrality is initially observed? | This means plane of focus is on the object. Accommodative response = Accommodative demand. A value of 0.00D is recorded at Lag of accommodation. |
| What is done if, during Nott Ret, Against motion is initially observed? | This indicates the the accommodative responce is greater than the accommodative demand & that the point of fixation is in front of the doc. Recorded as just "Minus Lag" |
| What is considered a normal finding MEM ret? | MEM (monocular estimation method) measured accommodative lag should be +.50D and symmetric. |
| What is the setup for MEM ret? | Normally done outside of phoropter over BVA. Trial lenses are quickly placed in frnt of eye, streaked & removed (you want to assess the accommodative response, not change accommdtive demand)Recodings are made in the same way as NOTT Ret |
| What is the general procedure for MEM ret? | See P 16 of 17 |
| What is the scoping distance for MEM ret? What are the lighting conditions? | 1. 40 cm 2. NO ADDITIONAL OVERHEAD LIGHTING IS USED |
| Which test for lag preferred when using a phoropter? When not using a phoropter? | 1.Nott is the method of choice when using a phoropter 2.MEM is the method of choice when not using a phorpter |
| What are the two methods for evaluating the sustaining ability of accommodation? | Also called "endurance of focusing power" 1.Amplitude of accommodation decay test 2.Facility of accommodation decay test |
| How is the consistency of accommodation tested? | Evaluation of consistency of accmmdtn is done using dynamic ret findings over time. |
| In what capacities can dynamic retinoscopy be utilized? | 1.Bell, MEM, or Nott to measure accommodative lag 2.Over time to evaluate consistency of accommodation 3.To monitor any subjective accommodation test to see if the objective signs are consistent with subjective patient repsonses |
Created by:
mm_coady
Popular Science sets