Post- -trauma vision trauma vision Post Post- -trauma vision - PDF document

Post- -trauma vision trauma vision Post Post- -trauma vision trauma vision Post syndrome syndrome syndrome: syndrome: “ “myopia myopia” ” AND AND � Myopia Myopia � accommodative accommodative � Accommodative insufficiency � Accommodative insufficiency insufficiency? insufficiency? � Convergence insufficiency Convergence insufficiency � � Possible exotropia, exophoria Possible exotropia, exophoria � Steve Leslie Steve Leslie � Photophobia Photophobia � B Optom FACBO FCOVD B Optom FACBO FCOVD � � Decreased blink rate Decreased blink rate � Spatial disorientation Spatial disorientation � � Balance and postural difficulties Balance and postural difficulties � ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 PTVS symptoms PTVS symptoms I ncidence I ncidence � Diplopia Diplopia � In my experience: In my experience: � � – Any traumatic closed head injury resulting Any traumatic closed head injury resulting � Objects appear to move Objects appear to move – � in coma, with initial global effects on in coma, with initial global effects on � Visual memory problems Visual memory problems � motor and cognitive function motor and cognitive function � Staring behaviour Staring behaviour � – – Typically involves midbrain Typically involves midbrain � Poor tracking ability Poor tracking ability � � Asthenopic symptoms Asthenopic symptoms � ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 1

Frequency (Kowal 161 Frequency (Kowal 161 Differential Differential pts) pts) � 16% poor accommodation 16% poor accommodation � Spasm of the near reflex Spasm of the near reflex � � – Accommodative excess Accommodative excess � 19% 19% pseudomyopia pseudomyopia (55% persisted) (55% persisted) – � – Miosis – Miosis � “ “4 had poor accommodation despite 4 had poor accommodation despite � – Esophoria/tropia – Esophoria/tropia pseudomyopia” pseudomyopia ” � Accommodative spasm Accommodative spasm � – Excessive accommodation tonus: should – Excessive accommodation tonus: should it be excessive when measured at it be excessive when measured at distance and near? distance and near? ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 “Pseudomyopia “ Pseudomyopia” ” Treatment Treatment � The excess accommodation disappears The excess accommodation disappears � Atropinisation Atropinisation � � with cycloplegia cycloplegia, but commonly recurs , but commonly recurs with – “ “Treatments using Treatments using cycloplegics cycloplegics with with – as cycloplegia as cycloplegia wears off (London, wears off (London, sunglasses and bifocals were.. uniformly sunglasses and bifocals were.. uniformly rejected by patients… … (Kowal) (Kowal)” ” rejected by patients Kowal) Kowal) � Thus, it is excessive accommodation ie Thus, it is excessive accommodation ie � � Refractive correction, near addition Refractive correction, near addition focusing closer than normal when � focusing closer than normal when tested at distance, but why? tested at distance, but why? � Vision therapy: accommodative facility Vision therapy: accommodative facility � ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 2

Neurological causation Control of Neurological causation Control of (London) accommodation (London) accommodation � “ “..shift secondary to an ..shift secondary to an irritative irritative lesion lesion � Learned proximal information Learned proximal information � � that affects the parasympathetic that affects the parasympathetic � Blur Blur � innervation, resulting in ciliary innervation, resulting in ciliary body body � Conscious/voluntary Conscious/voluntary � contraction..” contraction.. ” � Convergence Convergence � � “ “secondary to neural irritation of the secondary to neural irritation of the � parasympathetic third nerve parasympathetic third nerve subnucleus, or possibly subnucleus , or possibly disinhibition disinhibition of of brain stem centres..” ” brain stem centres.. ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 Accommodation… … Accommodation sensorimotor intelligence intelligence Accommodation Accommodation sensorimotor ( ( Wachs Wachs) ) � Identification of an object fixated in space Identification of an object fixated in space � ..a self ..a self- -directed, intrinsically directed, intrinsically � � along the third dimension of the learned along the third dimension of the learned constructed knowledge of body, constructed knowledge of body, visual space construct. visual space construct. physical world and practical physical world and practical � The Z axis is constructed through � The Z axis is constructed through use… use …( (Wachs Wachs) ) experience of the baby and child through experience of the baby and child through proprioceptive proprioceptive and and kinaesthetic kinaesthetic feedback of feedback of eye hand activities. eye hand activities. � Spatial construct to accurately Spatial construct to accurately localise localise the the � identification system in space. identification system in space. ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 3

X and Y axes X and Y axes Dark focus Dark focus � Given by the egocentric laterality of Given by the egocentric laterality of � Location of accommodation in space in Location of accommodation in space in � � the body, and gravitational vertical of the absence of visual information the body, and gravitational vertical of the absence of visual information the body. the body. � Young adults Young adults � � Disturbances of the learned X and Y Disturbances of the learned X and Y � – Mean 1.6D (62.5 cms), range 0 – Mean 1.6D (62.5 cms), range 0- -4D 4D spatial coordinates (ambient system) spatial coordinates (ambient system) � Large variations in studies Large variations in studies � eg by hemianopia, or eg by hemianopia, or � But individuals relatively stable But individuals relatively stable � midbrain/brainstem trauma, could midbrain/brainstem trauma, could � Gradual changes due to continued Gradual changes due to continued � disrupt the basis for the Z axis disrupt the basis for the Z axis close work close work ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 Dark focus Dark focus Concept of dark focus Concept of dark focus � Changes with nervous system activity Changes with nervous system activity � Resting point of accommodation Resting point of accommodation � � � Measurement by laser Measurement by laser optometer optometer � We focus OUT for distance tasks We focus OUT for distance tasks � � � Clinically measured by a Clinically measured by a � And focus IN for near tasks And focus IN for near tasks � � stigmatoscope ie light of a retinoscope ie light of a retinoscope stigmatoscope in a dark room in a dark room � But results variable But results variable � ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 4

Mathematics! Mathematics! � Myopia is a relative posturing of the Myopia is a relative posturing of the � identification system closer in space identification system closer in space than the demand (zero at 6 metres) than the demand (zero at 6 metres) � Myopia of 1 dioptre means the Myopia of 1 dioptre means the � identification system is localising identification system is localising at 1 at 1 metre from the individual metre from the individual 40 cms 6 metre � Myopia of 2 D means it is at 50 cms Myopia of 2 D means it is at 50 cms � Dark focus � Etc Etc � resting locus of ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 accommodation Accommodative Accommodative Pattern of PTVS Pattern of PTVS insufficiency insufficiency � Moderate degree of myopia, and moderate � Moderate degree of myopia, and moderate � A lag of accommodation measured by near A lag of accommodation measured by near � to severe degree of accommodative to severe degree of accommodative retinoscopy at 40 cms is a measure of less retinoscopy at 40 cms is a measure of less insufficiency insufficiency response than the demand of 2.5 D response than the demand of 2.5 D � It is not accommodative spasm in the true It is not accommodative spasm in the true � � � A lag of 1 D means a response of 1.5 D A lag of 1 D means a response of 1.5 D sense, since there is excessive focus at sense, since there is excessive focus at distance but insufficient focus at near distance but insufficient focus at near (2.5- (2.5 -1.0), and identification is 1.0), and identification is localising localising at at � Patterns (London) Patterns (London) � 67 cms 67 cms – Transient case which resolves Transient case which resolves – � A lag of 2 D indicates a spatial value of A lag of 2 D indicates a spatial value of � – Commonly chronic but stable mild myopia – Commonly chronic but stable mild myopia 2metres etc 2metres etc – Less commonly, progressive myopia Less commonly, progressive myopia – ICBO 2006 ICBO 2006 ICBO 2006 ICBO 2006 5