Vision Disorders
Conditions
Brief summary
This study will compare near clinical oculomotor parameters (heterophoria, vergence ranges, AC/A and accommodative findings) measured when lenses and/or prisms are introduced using three different instruments namely: (i) a standard manual phoropter, (ii) an electronic phoropter and (iii) a wearable adaptive refractor (VisionFit).
Detailed description
Previous studies have demonstrated differences in a number of near oculomotor parameters \[e.g., heterophoria, accommodative convergence to accommodation (AC/A) ratio\] 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. Further, a number of standard clinical oculomotor procedures require the use of Risley rotary prisms. While prism is typically introduced in a smooth, ramp-like fashion with manual phoropters, step changes in prism are created with electronic phoropters. The precise effect of these variations on clinical measurements is unclear. Accordingly, after a routine refractive examination, a standard clinical near assessment (comprising near heterophoria, AC/A ratio, horizontal vergence ranges, amplitude of accommodation and negative and positive relative accommodation) will be carried out on the same individuals through: (i) a standard manual phoropter (American Optical model 11625), (ii) an electronic phoropter (Topcon CV-5000) and (iii) a wearable adaptive refractor (VisionFit). The latter resembles a trial frame mounted on a helmet carrier (similar to a binocular indirect ophthalmoscope headset) but includes adaptive lenses that can be changed electronically.
Interventions
DEVICEPhoropter
Each subject will be tested on 3 separate occasions using either the manual phoropter (American Optical 11625), electronic phoropter (Topcon CV-5000) or the wearable adaptive refractor (VisionFit). Oculomotor measurements, i.e., heterophoria, vergence ranges, AC/A and accommodative findings will be measured at each session using the different devices. Each session will be separated by a minimum of 24 hours and a maximum of 14 days.
Sponsors
State University of New York College of Optometry
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
DIAGNOSTIC
Eligibility
Sex/Gender
ALL
Age
18 Years to 30 Years
Healthy volunteers
Yes
Inclusion criteria
* Corrected visual acuity of at least 20/20 (logMAR = 0.0) or better in each eye
Exclusion criteria
* Strabismus, amblyopia, manifest ocular disease.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Near horizontal heterophoria | approximately 15 minutes | Near horizontal heterophoria (measured in prism diopters) will be recorded using both the Von Graefe and Modified Thorington techniques using each of the three lens presentation devices. The single set of measurements will be recorded approximately 15 minutes after the start of the trial. |
| Accommodative convergence to accommodation (AC/A) ratio | approximately 15 minutes | The AC/A ratio will be calculated from measurements of near horizontal heterophoria (quantified in prism diopters) will be recorded using the Modified Thorington technique at 3 different accommodative stimulus levels (1.5D, 2.5D and 3.5D). Measurements will be obtained using each of the three lens presentation devices and calculated in units of prism diopter per diopter accommodation.The single set of measurements will be recorded approximately 15 minutes after the start of the trial. |
| Horizontal near vergence ranges | approximately 15 minutes | Near base-in and base-out vergence ranges will be measured (in prism diopters) while the subject fixates a near target. Measurements will be expressed in terms of the blur point, break point and recovery measurement .The single set of measurements will be recorded approximately 15 minutes after the start of the trial. |
| Minus lens amplitude of accommodation | approximately 15 minutes | Minus lens amplitude of accommodation (measured in diopters) will be recorded using each of the three lens presentation devices.The single set of measurements will be recorded approximately 15 minutes after the start of the trial. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Negative and Positive Relative Accommodation (NRA and PRA) | approximately 15 minutes | NRA and PRA (measured in diopters) will be recorded using each of the three lens presentation devices.The single set of measurements will be recorded approximately 15 minutes after the start of the trial. |
Countries
United States
Outcome results
None listed