Relating asthenopic symptoms to optometric measures and parameters of binocular vision
2022-08, Joss, Joëlle, Jainta, Stephanie
Asthenopic symptoms are related to heterophoria and problems of binocular vision. In a recent paper, we showed that vergence drift and fixation durations are related to symptoms (CISS-questionnaire), but optometric measures such as heterophoria, vergence or accommodative facility, AC/A-ratio or NPC did not significantly add to the explained variance of asthenopia. We re-analysed our data, in which binocular eye movements were recorded (EyeLink II) for 64 participants, and linear regression analyses related all parameters of binocular coordination (objective heterophoria, vergence drift, saccade disconjugacy, fixation disparity and fixation duration), and the above-mentioned optometric tests to 4 symptoms factors (eye comfort, reading process, image quality and fatigue), which we identified by a factor analysis of the CISS-questionnaire. Objective heterophoria and fixation duration predicted 20% of the variance in symptoms concerning the reading process (factor 2). Furthermore, fixation duration seems to be slightly, but not significantly, related to symptoms addressing fatigue (factor 4), whereas optometric tests are not significantly related to any asthenopia factor. Overall, objective measures during reading relate to asthenopic symptoms, however the lack of asthenopic symptoms prediction by daily optometric parameters is still unexplained. Therefore, further research is needed to find out suited optometric parameters to infer asthenopic symptoms.
Binocular advantages in reading revisited. Attenuating effects of individual horizontal heterophoria
2019-12-09, Jainta, Stephanie, Joss, Joëlle
Reading with two eyes necessitates efficient processes of binocular vision, which provide a single percept of the text. These processes come with a binocular advantage: binocular reading shows shorter average fixation durations and sentence reading times when compared to monocular reading. A couple of years ago, we showed for a small sample (N=13) that binocular advantages critically relate to the individual heterophoria (the resting state of vergence). In the present, large-scale replication we collected binocular eye movements (Eyelink II) for 94 participants who read 20 sentences monocularly and 20 sentences binocularly. Further, individual heterophorias were determined using three different optometric standards: objective eye tracking (EyeLink II at 60 cm), Maddox wing test (at 30 cm) and measures following the “Guidelines for the application of the Measuring and Correcting Methodology after H.-J. Haase” (MCH; at 6 m). Binocular eye movements showed typical pattern and we replicated (1) binocular advantages of about 25 ms for average fixation durations and (2) a reduction in binocular advantages when heterophoria increased – but only when heterophoria was identified by EyeLink II or Maddox wing measures; MCH measures of heterophoria did not affect binocular advantages in reading. For large heterophorias binocular reading even turned into a disadvantage. Implications for effect estimations and optometric testing will be discussed.
Do standard optometric measures predict binocular coordination during reading?
2021-01-21, Joss, Joëlle, Jainta, Stephanie
In reading, binocular eye movements are required for optimal visual processing and thus, in case of asthenopia or reading problems, standard orthoptic and optometric routines check individual binocular vision by a variety of tests. The present study therefore examines the predictive value of such standard measures of heterophoria, accommodative and vergence facility, AC/A-ratio, NPC and symptoms for binocular coordination parameters during reading. Binocular eye movements were recorded (EyeLink II) for 65 volunteers during a typical reading task and linear regression analyses related all parameters of binocular coordination to all above-mentioned optometric measures: while saccade disconjugacy was weakly predicted by vergence facility (15% explained variance), vergence facility, AC/A and symptoms scores predicted vergence drift (31%). Heterophoria, vergence facility and NPC explained 31% of fixation disparity and first fixation duration showed minor relations to symptoms (18%). In sum, we found only weak to moderate relationships, with expected, selective associations: dynamic parameter related to optometric tests addressing vergence dynamics, whereas the static parameter (fixation disparity) related mainly to heterophoria. Most surprisingly, symptoms were only loosely related to vergence drift and fixation duration, reflecting associations to a dynamic aspect of binocular eye movements in reading and potentially non-specific, overall but slight reading deficiency. Thus, the efficiency of optometric tests to predict binocular coordination during reading was low – questioning a simple, straightforward extrapolation of such test results to an overlearned, complex task.