| Topic | Details |
| Purpose | Eccentric Circles – Red/Green (1 Pair Clear) is a binocular vision training and diagnostic tool used for anti-suppression testing, binocular fusion assessment, fixation disparity evaluation, and vergence training. When used with red/green anaglyph glasses, each eye views a different stimulus, forcing the visual system to work binocularly to fuse the images. This allows clinicians to evaluate suppression and train convergence and divergence in free-space conditions. |
| Target users | The tool is designed for optometrists, ophthalmologists, orthoptists, and vision therapists, as well as patients undergoing binocular vision therapy or orthoptic rehabilitation. It is primarily used in professional clinical settings or supervised home therapy programs rather than general visual screening. |
| Optotypes / Symbols | The visual stimulus consists of concentric eccentric circle patterns printed on transparent cards. The central region contains differential words such as “FUSE”, “TEXT”, and “THIS”, which appear differently to each eye under red/green viewing conditions. These elements function as anti-suppression indicators. Additional alignment hash marks on the outer rings assist in detecting subtle fixation disparity or binocular misalignment. |
| Scaling / Spacing | The circles are fixed in size and are not arranged in graded acuity scales. Vergence demand is created by shifting the transparent cards horizontally relative to each other, introducing controlled binocular disparity. This allows the clinician to challenge fusion by increasing convergence or divergence demand during therapy exercises. |
| Range of Acuity / Line Sizes | Not applicable. The device is not intended for visual acuity testing and therefore does not include multiple acuity lines or optotype size variations. Its primary function is binocular fusion and suppression assessment. |
| Testing Distance | The cards are used at a near working distance, typically around 40 cm, during binocular vision therapy or fusion testing. The design supports near free-space fusion exercises rather than distance vision testing. |
| Dimensions | The product typically consists of two clear plastic cards approximately 6 × 7 inches in size, providing sufficient viewing area for overlapping eccentric circle patterns during fusion exercises. |
| Mounting | The cards are intended for free-space use and are typically held by the clinician or patient. They are not wall-mounted or framed, allowing flexible positioning during binocular therapy activities. |
| Features | Key features include differential anti-suppression text (“FUSE”, “TEXT”, “THIS”), concentric eccentric circle fusion targets, and alignment hash marks to help detect fixation disparity. When used with red/green glasses, the device can be used for vergence training (both convergence and divergence) by adjusting the relative position of the cards. |
| Accessories | The standard package includes one pair of clear red/green eccentric circle cards (one card for each eye stimulus). Additional accessories such as red/green glasses or storage cases may be supplied separately depending on the vendor. |
| Durability / Material Qualities | The cards are typically manufactured from clear plastic or acrylic sheets with high-contrast printed targets. This material offers greater durability and moisture resistance compared to paper charts, although repeated use may cause surface scratches or gradual print wear over time. |
| Usability / Marker of Quality | The design is simple yet clinically sophisticated, combining anti-suppression text, eccentric circle fusion targets, and alignment markers in a single tool. High-quality versions provide clear printing, accurate target alignment, and durable transparent material, making them reliable tools for binocular vision therapy and professional orthoptic assessments. |
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