ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ Tεχνικές Ηλεκτροφυσιολογίας Σωτήρης Πλαΐνης, PhD ΒΕΜΜΟ Viual Science Lab Ιανουάριος 2004 Κλινική ηλεκτροδιαγνωστική Καταγραφή ηλεκτρικής δραστηριότητας από το οπτικό σύστηµα Λειτουργική αποµόνωση οµάδων κυττάρων στην οπτική οδό Ηλεκτροαµφιβληστροειδογραφία (ERG) ERG (dital retinal component) Pattern ERG (proximal retinal component) Οπτικά Προκλητά υναµικά (VEP) VEP (cortical connectivity) Pattern VEP (pathway delay, viual acuity) Ηλεκτροοφθαλµογραφία (EOG) (retinal pigment epithelium ) Πολυεστιακό (multifocal) ERG/VEP (retinotopic tudie) Ηλεκτροµυογραφία (EMG) Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 2 Referral Indication Confirmation of Neurological or Ophthalmological Dieae Inherited retinal degeneration Ocular hypertenion/glaucoma Retinal detachment (epecially with opaque media) Multiple cleroi Certain Inflammatory Ocular Dieae Retinal ichaemia e. g., diabetic vacular dieae, retinal vein and artery occluion Endophthalmiti Cone dytrophie Unexplained Viual Lo Paediatric Neurology Monitoring Health Toxicity Quantitative Aement of Viual Dieae Aement of Retinal and Optic Nerve Function Following Trauma ERG Light diffuion The lightevoked ERG i the record of a diffue electrical repone generated by the neural and nonneuronal cell in the retina. Binocular timulation but monocular repone Widefield (Ganzfeld) timulation hould be ued. Focal flahe may be ued for certain pecialized ERG tet (With focal flahe, the area of retinal illumination i not uniform, and it extent i unknown). Reearch Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 3 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 4 Electrode Recording electrode: Electrode that contact the cornea or nearby bulbar conjunctiva are trongly recommended for baic fullfield recording contact len electrode (Topical anetheia i neceary) conductive fiber and foil (no anetheia ) conjunctival loop electrode Contact len electrode will provide the highet amplitude and mot table recording; uch electrode hould be centrally tranparent with an optical opening a large a poible, and incorporate a device to hold the lid apart but may not be required for other type of corneal and conjunctival electrode. Electrode Reference electrode: may be incorporated into the contact len peculum aembly to make contact with the conjunctiva ("bipolar electrode"). Thi i the mot table configuration electrically. alternatively, can be placed near each orbital rim temporally a a reference for the correponding eye. Ground Electrode: A eparate kin electrode hould be attached to an indifferent point and connected to ground. Typical location are on the forehead or ear. Conductive gel Skin impedance Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 5 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 6
ERG electrode ERG electrode Electrode on or near the eye DTL fibre DTL fibre Skin electrode Skin electrode Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 7 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 8 Light ource Stimulu duration. The tandard i baed on timuli of duration coniderably horter than the integration time of any photoreceptor. Thu, the light timulu hould conit of flahe having a maximum duration of about 5 m. Stimulu wavelength. Mot flah timuli in ue have a color temperature near 7000 K, and they hould be ued with dome or diffuer that are viibly white. Colored filter can be ued to enhance the eparation of rod and cone repone. Stimulu trengthtandard flah. A tandard flah (SF) i defined a one of timulu trength (in luminou energy per quare meter) at the urface of the Ganzfeld bowl of 1.53.0 cd..m 2 (candelaecond per meter quared). Thi i equivalent to luminance.time. Background illumination. In addition to producing flahe, the timulator mut be capable of producing a teady and even background luminance of 1734 cd.m 2 acro the full field. A white background i ued for thi tandard, but we recognize that colored background may alo be ued for pecial purpoe. Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 9 Patient preparation Pupillary Dilation. pupil normally are maximally dilated for all ERG recording pupil ize hould be noted. Preadaptation to light or dark. The recording condition outlined below pecify 20 min of dark adaptation before recording rod repone, and 10 min of light adaptation before recording cone repone (If corneal electrode are ued, the wearing time can be minimized by dark adapting firt, and inerting the electrode under dim red light at the end of the adaptation period). Preexpoure to light. Fluorecein angiography or fundu photography hould be avoided before ERG teting, but if thee examination have been performed, a period of dark adaptation of at leat one hour i needed. It i uually preferable to record cotopic repone to weak flahe before the mixed and cone repone to more intene flahe, to minimize light adaptation Fixation. A fixation point hould be incorporated into timulu dome (not o critical). Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 10 Κλινική ηλεκτροδιαγνωστική ERG (1) A repone to a trong flah in the darkadapted eye (tandard) (2) A repone to a weak flah ( ariing from the rod) in the darkadapted eye (3) Ocillatory potential (4) A repone to a trong flah (ariing from the cone) in the lightadapted eye (5) Repone to a rapidly repeated timulu (flicker) 50µV 50µV Single flahe mixed rod/cone 30Hz flicker iolate cone Dim blue flah iolate rod Strong white flah combined repone Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 11 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 12
Darkadapted ERG Generator Site of the ERG bwave b i.t. b amp a amp a i.t. awave Implicit time (i.t.)= time from timulu until peak of activity Amplitude (amp)= voltage magnitude at peak of activity awave originate from the photoreceptor layer bwave i a glial potential originating from the Müller cell and the bipolar cell OP originate from amacrine cell flah ERG reflect electroretinal activity dital to the ganglion cell layer Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 14 Ocillatory Potential (OP) ERG κλινικά παραδείγµατα a ubcomponent of the ERG een on acending limb of the bwave Wachtmeiter (1977) demontrated OP originate from amacrine cell in the inner plexiform layer OD OS OP2 OP1 OP3 OP4 5 Uv 15 m υστροφίες ραβδίων/κωνίων (receptor dytrophie) Μελαγχρωστική αµφιβ/δοπάθεια (retiniti pigmentoa) Congenital tationary nightblindne Φυλοσύνδετη ρωγµή αµφιβ/δούς (Xlinked retinochii) Bet dieae Toxoplamoi Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 15 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 16 υστροφία κωνίων Μειωµένη απόκριση ραβδίων MM Age 6 SG Age 15 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 17 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 18
Retiniti pigmentoa Congenital tationary night blindne PC Age 34 SD Age 11 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 19 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 20 Φυλοσύνδετη ρήξη αµφιβ/δούς Pattern ERG (PERG) TH Male Age 2½ Elicited to pattern timulation (uually checkerboard or bar grating) much lower amplitude than flah ERG fixation i critical for PERG, not flah ERG PERG reflect activity in the ganglion cell layer Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 21 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 22 Tranient PERG Ηλεκτροοφθαλµογράφηµα (EOG) At low temporal frequencie (3 Hz or le) a tranient PERG i obtained. The waveform i characteried by a mall initial negative (N) (at ~35 m), which will be referred to a N35. Thi i followed by a later and larger poitive (P) component (45 60 m) which i typically denoted a P50. Thi poitive portion of the waveform i followed by a large negative component at about 90 100 m (N95). For the tranient PERG, amplitude meaurement are made between peak and trough: The P50 amplitude i meaured from the trough of N35 to the peak of P50. Μέτρηση ακεραιότητας µελάγχρουν επιθηλίου Ηλεκτρόδια καταγράφουν κινήσεις των οφθαλµών Η απόκριση µεταβάλλεται µε την προσαρµογή στο σκοτάδι Καταγραφή σακκαδικών κινήσεων 12 λεπτά στο φως 12 λεπτά στο σκοτάδι Arden index (Light peak dark trough): φυσιολογικό > 180% Βet dieae: ~ 100% Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 23 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 24
+ + + + + + + + volt Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 25 Volt Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 26 + + + + + + + + _ + + + + + + + + Volt Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 27 Volt Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 28 + + + + + + + + EOG 12 Dark 3 12 Light _ Arden index = 214% 12 Volt 20 30deg accade Right eye 20 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 29 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 30 500µV
ΕOG EOG Bet dieae 12 Dark 3 12 Light Arden index = 107% 12 500µV 2 30deg accade Left eye 2 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 31 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 32 Οπτικά Προκλητά υναµικά (VEP) Οπτικά Προκλητά υναµικά (Viual Evoked Potential) Αποκρίσεις αθροιστικών σχηµάτων του φλοιού Ηλεκτρόδια πάνω από το ινιακό λοβό or a range of pattern (grating/checkerboard) Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 33 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 34 Electrode location Pattern reveral VEP 1A. Location of Active and Reference Electrode for Standard Repone. The active electrode i located along the midline at Oz. The reference electrode i located at location Fz. The ubcript z indicate a midline poition. Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 35 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 36
VEP RT andcontrat VEP contrat Vailev et al., 2002 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 37 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 38 VISUAL EVOKED POTENTIALS GP Age 12 Normal VEP 95/7733 VEP Οπτική νευρίτιδα Right Left 120 60 Right Left 30 15 5µV Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 39 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 40 VEP κλινικά παραδείγµατα Multifocal ERG Optic Neuriti Multiple cleroi Glaucoma Thyroid eye dieae Tranmiion delay The mferg i a technique for aeing the local ERG from different region of the poterior retina. Electrical repone from the eye are recorded with a corneal electrode jut a in conventional ERG recording, but the pecial nature of the timulu and analyi produce a topographic map of ERG repone. For the routine mferg, the retina i timulated with a computer monitor or other device that generate a pattern of element (typically hexagon), each of which ha a 50% chance of being illuminated every time the frame change By correlating the continuou ERG ignal with the on or off phae of each timulu element, the focal ERG ignal aociated with each element i calculated. Data can be Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 41 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 42
Multifocal ERG EMG Meauring dicomfort glare EMG recording Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 43 Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 44 Meauring dicomfort glare Ηλεκτροµυογράφηµα (EMG) Stimulu on off Subject SP Noie Raw data Relative Amplitude Peak of rectified data Binocular glare 950 lux Raw data Peak of rectified data Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 45 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Time (econd) Σ. ΠΛΑΪΝΗΣ, ΒΕΜΜΟ "ΟΠΤΙΚΗ ΚΑΙ ΟΡΑΣΗ" 46