To evaluate the effect of size and accommodative characteristics of fixation targets on the distant angle of deviation in patients with intermittent exotropia in the context of interobserver and intraobserver variability of the prism cover test.
A prism cover test was employed to assess the magnitude of the deviations present [ 22].
(6) Orthoptic evaluation including conjugate eye movements; cover-uncover test; cover-test and prism cover test where it was necessary.
The angle of deviation was measured at 6 m and 1/3 m using alternate prism cover test.
Complete ophthalmologic examinations including measurement of binocular alignment using a prism cover test, and dilated fundus examination were performed.
Deviation was measured using the alternate prism cover test for distance (6 m) and near (33 cm) in all 9 positions of gaze using accommodative targets with their best optical correction preoperatively.
Examination findings recorded included LogMAR visual acuity; total near and distance angle of strabismus using the alternate prism cover test and near stereoacuity using the Frisby Near Stereoacuity Test (FNS™).
The battery of orthoptic tests included: corrected visual acuity, cover testing, ocular motility assessment, convergence (NPC) and accommodation near points (NPA), prism fusional ranges to blur, diplopia and recovery, vergence and accommodative facility, TNO stereotest and prism cover test for measurement of heterophoria.
Assessment of ocular alignment and motility consisted of cover test, evaluation of saccadic, smooth pursuit and vergence eye movements, retinal correspondence (Bagolini glasses), fusional vergence (20D or fusional range), stereopsis (Frisby near test), prism cover test, and lid and pupil function.
If the exodeviation at distance was larger than 10 PD compared with that at near, one eye of the patient was patched for 1 hour in order to eliminate fusional convergence, and the alternate prism cover test was repeated at near and at distance.
