|Title||Effect of Lens Presentation on the Clinical Oculomotor Assessment at Near|
|Author, Co-Author||Komal Shah, Joan Portello, Mark Rosenfield|
|Abstract|| Purpose: Previous studies have demonstrated differences in a number of near oculomotor parameters (e.g., phoria, AC/A ratio) when measured in a manual phoropter versus a trial frame. These differences may be due to variations in proximal vergence, differences in head and eye position and restriction of the peripheral visual field. The aim of this investigation was to determine whether differences in near oculomotor parameters exist for 3 types of phoropter, i.e, a standard manual phoropter, an electronic phoropter (Topcon CV-5000) and a wearable adaptive refractor (Adaptica VisionFit).
Method: After a routine refractive examination, a standard clinical near assessment (comprising near phoria, AC/A ratio, horizontal vergence ranges, amplitude of accommodation and negative and positive relative accommodation) was performed using each of the 3 devices described above in 30 young, visually-normal subjects.
Results: Significant (p < 0.05) differences in the findings for base-in (BI) blur and lateral heterophoria as measured with the Modified Thorington test were found between the 3 instruments. The mean BI blur values for the manual, automated and adaptive instruments were 21.5, 18.6 and 15.5 prism diopters, respectively. Mean values of horizontal phoria were 1.5, 0.9 and 4.1 prism diopters exophoria, respectively. In addition, trends were found for differences in AC/A ratio (p = 0.07) and BI recovery (p = 0.08) between the different instruments.
Conclusions: The method of introducing lenses, particularly prisms, during oculomotor testing at near can lead to significant differences in clinical findings. In addition to changes in the size of the visual field and direction of gaze during testing, the stability of the device and the use of step versus ramp stimuli may also be responsible for these observed differences. Accordingly, it is recommended that the method used to introduce lenses and prisms during clinical testing be included in the patient's record.
|Affiliation of Co-Authors||SUNY College of Optometry, SUNY College of Optometry|