R.Tong (F/14) complains of sometimes blurry far & near vision since many years ago. While wearing her glasses, we observe that she has alternating intermittent exotropia & her left eye tends to deviate out more. She is aware that her eyes will move alternatingly.
Vision without glasses
R: 6/45-
L: 6/120
Vision with existing glasses of 1+years
R: -3.00/-0.75×180 (6/6)
L: -3.50/-0.25×180 (6/6)
Examination shows:
R: -3.00/-0.75×180 (6/6), N5@40cm [R : dominant right eye]
L: -3.50/-0.50×180 (6/6), N5@40cm
Other assessments show:
Examination of 3D Vision (Random Dot 3S)
12.5″
(normal value: 12.5″)
Examination of Eye Alignment/Vergence (Cover Test)
alternating XT, moderate recovery @Distance (fixing Right eye)
alternating XT, moderate recovery @Near (fixing Left eye)
(normal value: orthophoria/NMD-No Movement Detected or small XP fast recovery)
ET = Esotropia is misalignment of the eye, eye is deviated inwards
XT = Exotropia is misalignment of the eye, eye is deviated outwards
NPC (Convergence – ability of eye to maintain a single clear near image) by RAF rule
TTN, TTN, TTN
(normal value: less than 7.5cm or to the nose, TTN)
NRA (accommodation analysis – ability to relax accommodation)
+2.75
(normal value: +1.50 to +2.50)
PRA (accommodation analysis – ability to stimulate accommodation)
-3.50
(normal value: -1.37 to -3.37)
Examination of Fusional Reserves (Convergent/Divergent reserve stamina) by Prism Bar
Distance, Base-Out/Convergent, PFV: 18/10
Distance, Base-In/Divergent, NFV: 10/x
Near, Base-Out/Convergent, PFV: 20/12
Near, Base-In/Divergent, NFV: x
(normal value: Break/Recovery)
Near, PFV: 7-17/3-11
Near, NFV: 15-31/10-22
[Scheiman et al, 1989]
R.Tong has alternating intermittent exotropia, her right eye can move outwards & sometimes her left eye moves outwards.. most of the time we see that her left eye is deviated outwards more. The good thing is that sometimes she still retains good eye alignment whereby both eyes are straight.. hence her 3D vision is still intact & optimum.
We will refer R.Tong to see an orthoptist & ophthalmologist promptly for further examination.. before the possibility of her exotropia becomes constant, in which one eye finally succumbs & being kicked out.. or we call the squint eye.