Balaji Technomed

Overview of Autorefractometer

An autorefractometer (or autorefractor) is a diagnostic device used in optometry and ophthalmology to measure a person's refractive error and prescription for glasses or contact lenses. It provides an objective measurement of how light changes as it enters the eye, helping eye care professionals determine whether someone is nearsighted (myopic), farsighted (hyperopic), or has astigmatism.

How It Works:

1. The patient looks into the machine at an image or light.

2. The device shines light into the eye and measures how it reflects off the retina.

3. It uses this reflection to calculate:

The degree of refractive error
The curvature of the cornea

4. The results provide estimated prescription values, usually including:

Sphere (SPH)
Cylinder (CYL)
Axis (for astigmatism)

Key Features:

Quick & Non-invasive
Objective Results (no patient response needed)
Often used before subjective refraction (manual testing with lenses)
Some advanced models include keratometry (measuring corneal curvature)

Who Uses It:

Optometrists
Ophthalmologists
Opticians
Vision clinics and hospitals

Advantages:

Fast and easy to use
Useful for children and non-verbal patients
Good starting point for prescription refinement

Limitations:

May not be 100% accurate on its own
Results often need subjective refinement by an eye care professional
Not suitable for patients with certain eye conditions (e.g. cataracts)

Overview of Keratometer:

A keratometer, also known as an ophthalmometer, is a diagnostic instrument used to measure the curvature of the anterior surface of the cornea, particularly the central 3 mm. This measurement is critical for assessing the corneal shape and power, and it's especially useful in:

Contact lens fitting
Detecting astigmatism
Evaluating corneal disorders (e.g., keratoconus)
Pre- and post-operative assessment (e.g., LASIK or cataract surgery)

How a Keratometer Works:

1. The patient looks into the device at a fixed target.

2. The keratometer projects light or images (usually mires) onto the cornea.

3. The reflected image is analyzed to calculate:

The radius of curvature of the cornea (usually in mm)
The corneal power in diopters (D)

4. It provides measurements in two principal meridians:

Flat meridian
Steep meridian

This helps in detecting and quantifying regular and irregular astigmatism.

Types of Keratometers:

Type Description Manual Keratometer Requires alignment by the operator; uses known object size and reflected image to calculate curvature. Automated Keratometer Often integrated with autorefractors; provides faster, user-friendly measurements. Photokeratoscope / Corneal Topographer Provides a full topographic map of the corneal surface, not just central curvature.

Typical Output Example:

Meridian Curvature (mm) Power (D) Horizontal 7.80 mm 43.25 D Vertical 7.60 mm 44.50 D

Difference in power indicates astigmatism.

Advantages:

Non-invasive and quick
Helps in proper contact lens selection
Essential for refractive and cataract surgery planning

Limitations:

Measures only the central cornea
Cannot detect subtle irregularities across the entire cornea
Affected by dry eyes or poor fixation

VARIOUS MODELS OF AUTO REFRACTOMETERS

auto refractometer
autorefractometer
auto ref keratometer
auto refracto keratometer

Rexxam (Shin Nippon) AR/ ARK

Classic, Compact, and Ergonomic Design

The Rexxam Auto Ref-Keratometer K-900 and Auto Refractometer R-800 deliver precise, reliable objective measurements in a sleek, space-saving design. Built for comfort and ease of use, these instruments support eye care professionals in their everyday clinical routines.

Key Features:

Compact Footprint – Saves valuable workspace without compromising functionality.
WTW (White-to-White) Measurement – Accurately measures corneal diameter, essential for contact lens fitting and other ophthalmic applications.
Pupil Size Measurement (Scotopic & Standard) – Automatically captures pupil diameter during objective measurement, with the ability to assess scotopic pupil size separately.
IOL Mode – Specialized mode for patients with intraocular lenses. A red/green color focus indicator aids alignment, particularly helpful when dealing with irregular reflections from implanted lenses.
Minimum Pupil Size Detection – Capable of measuring pupils as small as 2.0 mm in diameter.
DR-900 Integration – Seamless connectivity with Rexxam’s Digital Refractor DR-900 for enhanced workflow.
Wide Measurement Range – Accommodates a broad spectrum of refractive errors.

User-Centric Design:

Tilting Monitor – A flexible display with 30° left-horizontal and 40° vertical tilt ensures comfortable operation whether sitting or standing, and allows support for the patient during measurement.
Curved Headrest Design – The inward-curving headrest reduces external light exposure and minimizes patient distraction while maintaining comfort.
Capacitive Touch Controls – Responsive sensor buttons enhance usability and help keep the main screen free of fingerprints.
Ergonomic Joystick – Solid and intuitive, the joystick allows fast, comfortable, and accurate device control.
Flexible Print Options – Choose from three formats:
- Up to 10 sets of REF + KRT data
- 10 sets of REF + averaged KRT data
- Averaged REF + KRT data only

EYEVIS AR/ ARK

Key Features and Technologies

EYEVIS KR-9900 / RM-9900

Double-Zone Control Design - The new double-zone control design separates the fogging and measurement processes. Fogging occurs first to fully relax the human eye, followed by measurement. This sequence ensures the eye is in a natural state, helping capture an accurate diopter reading and enhancing overall measurement precision.

Advanced Refraction Measurement Technique - Utilizes a new refraction measurement method for more comprehensive image analysis, delivering more consistent and reliable data.

Mire Ring Double-Ring Measurement - The dual-ring system enables simultaneous focusing and measurement, increasing the number of measurable points to significantly improve keratometry accuracy.

Rotational Prism Technology - The rotational prism evenly distributes the light source across the measurement rings, enhancing the quality and consistency of the projected rings for more stable measurement results.

Super Luminescent Diode (SLD) + High-Sensitivity CCD - Compared to standard LEDs, the SLD provides clearer imaging. Even with weak fundus reflections, the high-sensitivity CCD captures ring-shaped images effectively, allowing for measurements in cataract patients and a broader range of users.

Automatic Eye Tracking and Focusing - Advanced Y-direction auto-tracking and focusing technology quickly locks onto the pupil center, speeding up the measurement process and improving user experience.

Pupil and Corneal (White-to-White) Diameter Measurement - Pupil size measurement supports refraction analysis under various lighting conditions (Scotopic, Mesopic, Photopic). White-to-White measurement aids in IOL power calculations, especially for cataract surgery planning.

Peripheral Keratometry Measurement - Measures corneal curvature within a 3mm radius around the corneal center to assess peripheral steepness and provide a comprehensive understanding of corneal health.

RETRO Illumination Mode - RETRO mode enables quick evaluation of anterior segment opacities.

Tiltable 7-Inch Touchscreen - Features a 7.0-inch touchscreen with a 90° tiltable angle, allowing comfortable operation from both sitting and standing positions.

High-Speed Printer with Auto Paper Cut - Built-in thermal printer with automatic paper cutting for quick, easy printouts and seamless paper replacement.

Motorized Chin and Head Rest - Motorized adjustments ensure smooth, precise height changes for user comfort and operational efficiency.

One-Touch Unit Lock - Single-button lock secures the measuring unit to the device chassis for added stability during operation.

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Auto Refractometer/ Auto Ref-keratometer

Overview of Autorefractometer

How It Works:

Key Features:

Who Uses It:

Advantages:

Limitations:

Overview of Keratometer:

How a Keratometer Works:

Types of Keratometers:

Typical Output Example:

Advantages:

Limitations:

VARIOUS MODELS OF AUTO REFRACTOMETERS

Rexxam (Shin Nippon) AR/ ARK

Key Features:

User-Centric Design:

EYEVIS AR/ ARK

Key Features and Technologies

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