Description
The NIDEK ARK-500A is a compact, user-friendly auto refractometer/keratometer that combines reliable objective refraction and corneal curvature measurement in one tabletop unit. Designed for busy clinics and optical practices, the ARK-500A delivers fast, repeatable measurements with an intuitive interface and several automation features that reduce operator workload while improving patient throughput.
Key strengths of the ARK-500A include automated alignment and capture, multiple measurement modes, and flexible data output for integration with external devices (lensmeters, refractors, printers and clinic computers). The system uses an advanced optical measurement engine to provide objective refraction values (sphere, cylinder and axis) and keratometry readings (corneal curvature, corneal astigmatism and principal meridians) with fine measurement steps and clear numeric / image feedback on its display. An auto-tracking mechanism and auto-shooting function make measurements fast and minimize the need for manual adjustments; a motorized chin rest and ergonomic joystick/control layout further streamline patient positioning and operation.
The ARK-500A also includes convenient functions for clinical workflow: on-screen comparison of previous/current measurements, keratometry ring image display for visual confirmation, and RS-232 connectivity for exporting measurement data to charting systems, NIDEK refractors, and other peripherals. The unit’s robust, clinic-grade construction, straightforward user menu and ability to print or transmit measurement data make it suitable for general ophthalmology, optometry, contact lens fitting assessments, and pre-operative screening. Overall, the ARK-500A balances accuracy, automation and connectivity in a compact package ideal for practices that need dependable objective refraction and keratometry without complexity.
Specifications
| Measurement items | Refractometry (Sph/Cyl/Axis), Keratometry (corneal curvature radius, corneal power, astigmatism magnitude and axis) |
| Spherical measurement range | −30.00 D to +25.00 D (VD = 12 mm). |
| Cylinder measurement range | 0 to ±12.00 D. |
| Corneal astigmatism (keratometry) range | 0 to ±12.00 D (axis 0–180°). |
| Measurement step (refraction) | 0.01 / 0.12 / 0.25 D selectable. |
| Axis measurement | 0° – 180° |
| Keratometry measurement range (radius) | Typical corneal radius range (reported in mm / D depending on display) — see manual for exact presentation. |
| Auto-alignment / tracking | Vertical auto-tracking and auto-shooting function for hands-free capture when alignment is optimal. |
| Measurement modes | Auto (automatic capture), manual, repeat/average functions, view-comparison and ring image display for keratometry verification. |
| Chin rest | Motorized up/down chin rest for quick patient height adjustment. |
| Display | Built-in display with measurement readout and keratometry ring image (model dependent). |
| Interface / Connectivity | RS-232C serial port (data export to PC, printers, and NIDEK refractors/RT systems); some dealers note optional cables for lensmeter integration. |
| Peripheral compatibility | Can interface with NIDEK lensmeters (LM series) and refractors (RT series) for data import/export and workflow integration. |
| Power | AC powered (specify voltage for region; see manual for AC specifications). |
| Physical dimensions | Approx. 26 × 48.1 × 45.5 cm (example listing — check exact model documentation). |
| Weight | Varies by source/refurbishment; consult official manual or seller listing for exact shipping/pack weight. |
| Operating environment | See user manual for recommended temperature/humidity and storage conditions. |
| Printing / reporting | Built-in print function (with compatible printer) and on-screen printout of lensmeter data when connected. |
| Measurement speed | Rapid capture — auto shooting triggers measurement when alignment is achieved (speed depends on patient cooperation and selected averaging). |
