The College of Optometrists

Am a bit confused about assessing diplopia. If patient reports diplopia (longstanding)in certain postion during motilty, U then find out whether it's Horiz or Vert. Am a bit confused what to do after this?..can someone help, thanx

most diplopia is acute -that is sudden onset (after stroke, thyroid eye disease, MS, etc) and can vary with eye position (non comitant) or be the same degree where ever they look ( supra nuclear (as in stroke or ms). This is cared for by referal (urgent) and either patching, explaining how to hold the head to reduce the degree of diplopia or (more rarely) prisms of some sort. They would need to be told not to drive ( against the DVLC rules) and to return for further check up early.

Longstanding diplopia is rare as is controled by head posture usually. It is caused by abnormal oblique muscles as in browns or Duannes etc. It can also be caused by decompensated phoria in which case it maybe intermitent. Other causes are anisometropia etc, convergence insufficiency (then its only in the near point ) etc.

Firstly, check it is a bino thing and not a monocular diplopia ( due to cataract or distorted cornea for example). You can cover an eye and see if the diplopia persists - it wouldnot if it was a binocular thing.

Then you do a motility to map out how and if the deviation varies accross the binocular field.

Then you can check the head posture by getting them to fix a target and wag, nod and tilt their head -

You can then check their pupils for 3rd nerve involvement. Also have a look at the face, for lid droop, face droop etc. Ask about unilateral deafness etc.

Then you can decide the care plan.

If you know the cause (say TED)and see that the diplopia fits in with that and is small - for example the px had a tiny stroke leaving them with a small vertical diplopia then try a prism. You can use the normal ways for this - but sometimes the whole thing is paradoxical - especially if the px has had prisms for a long time already - beware changing them much.

If the px says its long standing - but you are not so sure. Ie they are fit and healthy and first test finds diplopia for no obvious cause - then although they may say they have always had it I would arrange a second opinion at HES.

I hope what I said is helpful. The vast majority of 'longstanding' diplopias are monocular (due to cataracts lens opacs, corneal problems), or spectacle wearing problems. A true binocular diplopia is rare, and longstanding rarer still.

'Cos people adapt to things most longstanding diplopia's will be masked by a head tild or posture of some type. So watch for that.

Then don't panic - just think laterally and be logical.

Do a cover test and then motility. You will know the vision and histsry and field defects from previous tests.

You will need to know the actions of the ocular muscles - but it is important to realise that they all work together - like your fingers do when they roll a marble about finger and thumb style.

Ocular muscle problems like Duannes, browns or old squint ops can give diplopia - they will all be worse in a particular gaze. Oblique muscle problems will cause a head tilt up or down and to one side - the bad eye is often carried higher than the good one.

You also need to know the ocular nerve actions. Then you are all set. any damage to an ocular nerve will typically cause a sudden diplopia worse in its field of action. In the primary position the eye will point away from its field of action. In third nerve problems the pupil can also be affected.

Going up the nerve path towards the brain you get to the ocular nerve nuclie which are in the mid brain, by the pons. Anything going funny here will cause the smooth action of the eyes to spoil -so you get nystagmus and also lack of tracking acuracy of the eyes. If the vertical gaze center (also in mid brain) goes wierd - then you get a vertical diplopia caused by the eyes miss tracking vertically (skew deviations). Most of these things seem comitant but may be worse in side gazes. Higher than the nuclie and you get miss looking, bino field reductions etc - but diplopia is more rare.

Thanx Palfi, i appreciate it. It kind of makes more sense now.