1. Snellen Chart - for visual Acuity - this is the distance from the chart at 6m/the last line read on the chart at 6m I think - eg 6/36 of 6/60 or 6/6 or 6/5,let them waer glasses, no glasses - pinprick hole in card. If worse that 6/60 - then bring to 3metres, if worse than 3/60, count fingers at 1metre, if not succesful, then Hand Movements, if not successful, Pen Torch at 1 metre.( record, CF, HM, PT) Also testing nearsightedness with newspaper/book - read. Test colour vision with Ishihara plates.
2. Fields - as in Visual Fields - if red pin doesnt work, waggling finger, map out presences of hemianopia, scotoma, enlarged blindspot. determine when pin disappears and reappears, moving laterally to horizontal within MID plane. Enlarged blind spot = papilloedema suggestive.
Inattentive test - visual neglect testd for with waggling finger, in pts left and right field, determing which finger, if not both, that the pt saw. Parietal lobe lesion - the finger that is ipsilateral to the lesion will be observed, but the finger on the opposite side will not be..., ie yes i see the right finger, no i dont see the left, means there is a lesion on the right side of the parietal lobe.
3. Reflex - as in direct and consensual light reflexes, swinging light reflexes, accomodation reflex. Swinging light reflex - looking for pupillary delayed constriction
Start of by observing size, shape - reg/irreg, of pupils,and also if presence of ptosis. - 3rd nerve palsy, Horner's.
For Direct and consensual - ask pt to fixate on distant object while testing.
For Swinging light reflex - swing a light from one eye to the next, observing for a sustained pupillary constriction suggestive of relative afferent pupillary defect {sign of Optic neuritis - think MS, other causes}
Accomodation - distant object, then my finger at 30cm from face, look for changes in pupillary size. Should constrict on accomodation, ie looking at near object.
4. SLOW PuRSUIT. The famous H - move horizontally, then vertically, then back to make the rest of the H, with your finger to cover all the eye movements. As the patient about : double vision & pain, watch for nystagmus.
Then From the top - hold 10 secs for fatiguability, and then move down slowly watching for lid lag - MG.
5.Double vision: Elicit whether the images are separated vertically or horizontally - and in which direction the separation is maximal.
'Tell me when you see double, okay so you see double now, can you close the right eye has one of the images disappeared? which one the outer or the inner, and now close the left eye...which one the outer or the inner disappeared?'
Here the issue is with the lateral or medial recti. The idea is that if when looking with the left eye, the outer object disappears when the right eye is covered , then the defect is in that right eye - which means that depending on if the direction we are looking to is to the left hand side - then it is a medial recti weakness, if we were looking to the right hand side when the right eye was covered, (and then it was still the outer image that disappeared), then we can say that it is a lateral recti problem of the right eye.
If in the scenario above the right eye was the problem, and the outer image disappeared on covering, then in the left eye when the test is switched, the inner image would have disappeared. Just a moot, side point.
Here is a link on diploplia http://www.jeffmann.net/NeuroGuidemaps/diploplia.html and I think some useful info on palsies.
Palsies to be aware of :
3rd (occulomotor)Nerve palsy: Ptosis, pupillary dilatation, eye is found 'down and out' (can be a posterior communicating artery aneurysm, or DM, vasculopathic infarction,trauma, meningeal inflammation, tumor, or ophthalmoplegic migraine).
the affected (pupil-dilated) right eye is abducted and tilted downwards (under
the unopposed influence of the 6th and 4th extraocular nerves) under the ptotic
upper eyelid on forward gaze (from link above)
4th (trochlear) Nerve Palsy:
The trochlear nerve (the fourth cranial nerve, also called the fourth nerve or
simply IV) is a motor nerve (a “somatic efferent” nerve) that innervates a
single muscle: the superior oblique muscle of the eye. An older name is pathetic
nerve, which refers to the dejected appearance (head bent forward) that is
characteristic of patients with fourth nerve palsies.The trochlear nerve is unique among the cranial nerves in several respects. It is the smallest nerve in terms of the number of axons it contains. It has the greatest intracranial
length. It is the only cranial nerve that decussates (crosses to the other side)
before innervating its target.
Finally, it is the only cranial nerve that exits from the dorsal aspect of the
brainstem.It enters the cavernous sinus, where it is joined by the other two extraocular nerves (III and VI), the internal carotid artery, and portions of the trigeminal nerve (V). Finally, it enters the orbit through the superior orbital fissure and innervates the superior oblique muscle.
The superior oblique muscle ends in a tendon that passes through a fibrous loop, the trochlea, located anteriorly on the medial aspect of the orbit. Trochlea means “pulley” in Latin; the fourth nerve is named after this structure.http://en.wikipedia.org/wiki/Trochlear_nerve
Diplopia (supposedly the commonest cause of vertical diploplia) with downward gaze - oblique muscle (SO4); orbital trauma, DM, HTN
Jeff Mann says, that the patient would typically have their head depressed slightly, chin down, and eyes looking upwards, I reckon to compensate for the fact that there is a downward gaze. He also says that they may have their head turned away from the side of the lesion, to compensate for the diploplia.
According to wilkinson, you get :
-incomplete depression of the affected eye in the adducted position
-some torsion of the eye in the orbit
-compensatory head tilt towards the opposite shoulder, may be present to obtain single vision whilst looking forward.
What I couldn't understand was why should have a downward gaze - hmm..when the muscle it self is important in that downward action. According to wilkinson, the 'SO' is important in looking down in the adducted position. Thus, when there is a palsy, this action is weakened if the patient tries to adduct the eye, so that it is slightly elevated. That's how you can see that specific problem of that supposed action of the SO.
Thus, on forward gaze, according to JM, the eye is slightly elevated, just slightly - its not looking up, but there is a slight space between the cornea the lower eye lid.
The reason for this is because of the opposing action of the fuctioning muscles. The lateral recti, medial recti, superior and inferior recti of the 3rd nerve and 6th nerve...work to elevate it slightly. I have no idea where 'downward gaze' comes from, other than that being a 'positioning of the head' rather than a placement of the eye itself. *SHIT*
6th Nerve Palsy: Abducens - Lateral recti :abducting abducens look laterally....lateral recti
There may be some inturning of the eye and double vision in the primary postion (because of weakness of eye abduction). There may be compensatory head turning (ie if right eye affected, head turns to right) to obtain a single vision whilst looking forward. No abduction of the eye. So the eye looks turned inwards basically.
This can be considered at times a false localising sign in patients with raised ICP;ms;small vascular lesions within the pons;pathology besides the cavernous sinus, in the superior orbital fissure, or orbit, adjacent nerves commonly inovled - 3/4/5a/2 if in the orbit.
4. Opthalmoscope/fundoscopy
-main things -
-explain what you are about to do - look with this opthalmoscope to check the back of the eye - this is basically like a torchlight with a magnifying glass attached to it - helps to illuminate and magnify the back of the eye - so I can look for any abnormalities or changes or just check to see if all is normal -it's a very simple procedure, that will not hurt, but may be a little uncomfortable - would that be okay?
-position paitnet so that they are seated with free acces to both sides of their chair
-BUT BEFORE THAT I'd JUST LIKE TO GENERALLY INSPECT YOUR EYE:
-start outer to inner - eyebrows - loss of hair, outer 1/3 indicative mostly of hypothyroidism, scares, check for periorbital oedema, any redness, swelling, discharge, foreign bodies, corneal abrasions or ulcerations, conjuctival changes or anaemia.
- know how to use fundoscope - ask pt to look at something in the distance and keep eye on it/fixated, switch on fundoscope make sure light is present by checking against hand, and set handle to zero if u dnt wear glasses. Turn down the lights. Hold fundscope in right hand - aiming to look at patient's right eye. Make sure u use your finger to focus - ie one finger at the front of the opthalmoscope - know how to hold it.
http://www.cornellsurgical.com/zWA11720.htm
Remember, the side with the horizontal dial is the side that faces the patient.
- Stand just in front of and to the right of the patient, asking them to look at a suitbale point a little above eye level and in the middle distance.
-Placing opthalmoscope to your right eye, place your left thumb on patient's eyebrow
-Bring head and opthamoscope slowly closer to the patients right eye. At about 30CM you need to check that you can see the red reflex. The absence of this suggests the presence of a a cataract.
-Keeping the reflex in view, continue to move in until your head is withint 1-2cm of your thumb and no closer!
-Keep the beam of light pointing slightly nasally so that you can keep focused on the disc when looking at the fundi....
-Improve the focus on the retina if need bee by alterning the setting of the lense with the dial.
- Tilt your head and opthalmoscope to follow the blood vessels towards the optic disc lying in the lower nasal quadrant of the retina.
-BEST TO START WITH OPTIC DISC THEN MOVE TO PERIPHERY but U USE THE VESSELS TO LEAD YOU TO OPTIC DISC
-so remember that the retina or back of the eye is split into 4 quadrants - lateral upper and lower, nasal upper and lower.
-CHANGES TO NOTE ON THE OPTIC DISC:
Margin - is it indistinct? - consider optic disc oedema, is there neovascularisation present (ie new blood vessel formation) - think Diabetic retinopathy
Colour - is it nice a pink = normal optic disc; are we looking at pallor of the optic disc? - in which case we are considering optic atrophy.
Contour - raised? - optic disc oedema.
CUP-DISC ratio: so the greater the inner cup, the more likely it is glaucoma - we calculate the ratio, measuring the diameter of the disc (the whole optic disc) and the cup, the inner aspect of the disc's diameter - the CUP/disc = ratio.
If this value is >0.5 = possible glaucoma, if 0.3-0.5 = normal, if CUP is absent : papilloedema!
So we've observed the optic disc - we want to have a good look at the periphery now:
-Avoid getting head or light into patient's line of sight
-Follow the blood vessles form the optic disc into the periphery (ie the area away from the disc, moving outwards). Then look at the 4 quads of the retina, and finally at the macula. The blood vessels - there are 4 - arteries and veins [superior/inferior, temporal/nasal].
- Remember that you're looking for microaneurysm, venous beading, dot and blot haemorraghes, ateriolar narrowing, AV nipping, copper or silver wiring, exudates -
please see following link for some really great images:
http://www.studentmess.com/index.php?d=163 (study carefully to get use to what you're seeing~)
http://studentmess.net/search_result.php?tid=19&title=retinopathy
Briefly on retinal changes:
Hypertensive retinopathy: (I-IV)
I minimal arteriolar narrowing - Silver wiring
II obvious arteriolar narrowing with focal irregularities: AV nipping, silver wiring
III previous changes, with haemorrhages (flame) and or hard exudates (retinal star) with or without cotton wool spots
IV Previous grade with papilloedema (malignant HTN)
Diabetic retinopathy (I-IV)
I Background (non proliferative) - dot (aneurysm), Blot (haemorrhage), hard exudates (yellow, lipid and fluid)
II Pre-proliferative (I with soft exudates and venous beading and oedema?)
III Proliferative - new vessels (neovascularisation, new friable vessels), tortuous fragile, and hence vitreous haemorrhages present, with fibrous growth into vitreous - getting floaters, can lead to increased ocular pressure, and painful glaucoma.
IV Maculopathy
These are the main things to be aware of above, tho there are other retinal changes (maybe talk about later)
- so having looked at all four quads, the retina and nasal and temporal areas, we want to ask the patient to look directly into the light to view the macula. Note its colour - pigmented - snile macular degeneration, and pink is normal) - then you say thank you and move to the left side to examine the left eye informing the patient that this is what you would like to do.
- repeat procedure
-turn of scope
- turn on lights
-thank the patient
-report and record your findings in the notes
-wash hands.
[Central retinal vein occlusion: blockage of retinal VEIN - common in DM and HTN pts. Fundus 'Stormy sunset' appearance.- with dilated engorged veings, dot and blot haems around them. Cotton wool spots and papilloedma may also be apparent.]
[Papilloedema: congested optic disc - in raised ICP, swollen disc and margins disappeared.
Optic atrophy: Retinal veins look congested, grey disc, pale, associated with loss of vision. Maybe 2ndry to glaucoma/retinal damage/ischaemia/poisoning]
Explanations: (from st.george's university handbook)
AV Nipping: when the arteriosclerotic arterial walls loose their transparency
and obscure the view of the underlying veing, on either side, this makes it look
as if the vein is 'nipped'
Haemorrhages: usually occuring in the most superficial nerve fibre layer of the retina, and because of the orientation of the fibres, they look linear or flame shaped
Hard exudate: yellowish white deposits in the deeper layers of the retina, they are accumulations of fats that have leaked out during retinal oedema
Cotton wool spots: retinal infarcts in the nerve fibre layer and are indicative of oedema. They are accumulations of degenerate axoplasm and are a grave prognostic sign. it happens in severe htn, which leads to obstruction of precapillary arterioles and hence cotton wool spot formation.
Narrowing: The primary response to systemic htn is narrowing. Older pts, vessels so stiff, may be minimal narrowing. Two sorts of narrowing; general along the lenght of vessel and Focal where vessels cross. Focal narrowing - likely that pt has htn.Vascular permeability causes oedema, haemorrhages, exudates
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