Pei Yi (F/13) non spectacles wearer, came for eye examination, with complaint of slight blurry far vision. She has big eyes but eyes look tired a bit.
Vision without glasses
R: 6/9-, 6/7.5-3
L: 6/9-
Examination shows:
R: PL/-0.75×175 (6/6) (+1.00 blur lens test 6/9-) [R: right dominant eye] R=L
L: PL/-1.00×180 (6/6) (+1.00 blur lens test 6/9-)
She prefers to have shortsightedness -0.25/-0.50 binocularly to see far better, +0.25 binocularly is not favoured
Other assessments show:
Examination of Eye Alignment/Vergence (Cover Test)
NMD @Distance
small XP, moderate recovery @Near
(normal value: orthophoria/NMD-No Movement Detected or small XP, fast recovery)
EP = Esophoria is misalignment of the eye, eye is deviated inwards
XP = Exophoria is misalignment of the eye, eye is deviated outwards
Examination of Eye Alignment/Posture (Howell Card) by 6^ Base Down on Right eye
Distance: 0 – 2 XP (blue part)
Near: 8 – 10 XP (blue part)
-1.00 Near: 6 – 8 XP (blue part)
(normal value: 0-1 EP or 0-3 XP @Distance; and 0-6 XP @Near)
EP = Esophoria is misalignment of the eye, eye is deviated inwards
XP = Exophoria is misalignment of the eye, eye is deviated outwards
NPC (Convergence – ability of eye to maintain a single clear near image) by RAF rule
9/11cm, 10/12cm, 11/13cm, 12/15cm, 13/16cm
(normal value: Break/Recovery in less than 10cm or to the nose, TTN)
NRA (Accommodation analysis – ability to relax accommodation) by plus lens
+1.25
(normal value: +1.50 to +2.50)
PRA (Accommodation analysis – ability to stimulate accommodation) by minus lens
-2.25
(normal value: -1.37 to -3.37)
MEM (Accommodation lag – to measure accommodation response seeing near target)
R: PL
L: PL
(normal value: +0.25 to +0.75)
Facility (Accommodation facility – ability to change focus: far to near or near to far) by Flipper +/- 1.50
BE: 6 cycle per minit(cpm), difficult with plus lens (1st lens)
R: 6 cycle per minit(cpm), difficult with plus lens(1st lens)
L: 7 cycle per minit(cpm), difficult with plus lens(1st lens)
Cannot clear +2.00
(normal value: 1 cycle = 2 words read
Monocular or R/L: 6cpm to 16cpm
Binocular or BE-both eyes: 4cpm to 14cpm)
Examination of Fusional Reserves (Convergent/Divergent reserve stamina) by Prism Bar
Near, Base-Out/Convergent, PFV: x/2/1 (1 – shadowy)
Near, Base-In/Divergent, NFV: x/12/10
1 BI OU Near, Base-Out/Convergent, PFV: x/6/4
2 BI OU Near, Base-Out/Convergent, PFV: x/4/2
(normal value: Break/Recovery)
Near, PFV: 10-28/7-21
Near, NFV: 7-19/5-15
Distance, PFV: 4-18/5-9
Distance, NFV: 4-10/2-6
[Scheiman – Adult Data]
Pei Yi has Convergence Insufficiency, CI. We know from these findings: (1) significant exophoria at near, (2) receded NPC & (3) decreased PFV @near. Upon these findings, we prompted whether or not she loses focus on near that she needs to blink2 eyes to focus back, she said yes.
She has 8-10 exophoria at near, in which her PFV needs to have at least twice (that is about 20) to pull in & balance her exophoric near posture.. but she only has 2. Her PFV is extremely low, we tried with prism 1BI in both eyes, it gives a little boost bringing PFV to 6.. but it is still low. Added minus lens at near can stimulate convergence, but it is not particularly helpful.. only able to bring her exophoria to 6-8.
MEM of less plus shows over focusing/Accommodation Excess.. possibly due to high exophoria & decreased PFV.. she is using her focusing to back up for her decreased PFV. Remember we mention about our two eye systems, accommodation/focusing & vergence being in support of one another to maintain clear single vision for us.
We let her try the stereogram but she is unable to appreciate & bring the two images together. We prescribe exercise glasses & Brock String VT and see her in 1month.