A guide to fitting techniques

Summary

The video script discusses the importance of accurate fitting for spectacles, detailing the use of the corneal reflex pupilometer to measure distances and various methods for determining lens height and position. It emphasizes the need for natural posture during measurements and the use of digital instruments for precise fitting.

Takeaways

• 👓 Accurate fitting is crucial for the quality of vision with spectacles.
• 📏 The method of fitting should be done with care and precision, avoiding shortcuts like dotting with a felt tip pen.
• 🏥 Optometrists use high-quality equipment and take care in their fitting process.
• 👁️‍🗨️ The corneal reflex pupilometer is used to measure the distance between visual axes, not just pupil centers.
• 🔍 The working distance knob should be set to infinity before taking the distance PD (pupillary distance).
• 📐 Alternative methods for measuring include drawing graticules, using small hypsometers, or the HMS height measurement system.
• 🔄 The Y stick gauge helps determine height by locking in the person's natural posture.
• 🔌 Digital instruments can measure monocular PDs, heights, vertex distance, face form angle, and pantoscopic angle.
• 🌞 Lenses that change color in the sun require the client to relax in a natural posture during measurement.
• 📏 The optical center of an aspheric lens must be adjusted based on the pantoscopic angle and the lens's position.

Q & A

Why is accurate fitting important for spectacles?

Accurate fitting is critical to the quality of vision obtained with any spectacles. It ensures that the eyewear fits comfortably and provides the correct optical alignment for optimal vision.

What is the issue with using a felt tip pen for fitting spectacles?

Using a felt tip pen for fitting spectacles has been shown to be less accurate than other methods. This can lead to poor vision quality and discomfort.

What is the purpose of the corneal reflex pupilometer?

The corneal reflex pupilometer is designed to measure the distance between the visual axes, not just the distance between the pupil centers. This helps in accurately fitting the spectacles.

What should be done before taking measurements with the corneal reflex pupilometer?

Before taking measurements, the working distance knob should be set to infinity and the frame should be in its final fitting position.

How does the corneal reflex pupilometer work?

The user is asked to look into a green circle with a light in the middle. The black line should pass through the very center of the reflex on the client's cornea, ensuring accurate measurement.

What are the alternatives for step three in the fitting process?

Alternatives include drawing a graticule on the inserts with a parallel rule, using small hypsometers, the HMS or height measurement system from Esor, and the Y stick gauge.

What is the purpose of the Y stick gauge in the fitting process?

The Y stick gauge helps lock in the position of the person's natural posture by locking in a pendulum, allowing for accurate height measurement.

Why is it important to measure monocular PDs and heights with digital instruments?

Digital instruments can measure monocular PDs, heights, vertex distance, face form angle, and pantoscopic angle, providing precise data necessary for accurate lens positioning.

How can a pen torch be used in the fitting process?

A pen torch can help illuminate the cornea and provide a corneal reflex as a reference point for heights. It can be held at the same level as the eyes for accurate measurements.

What is the significance of the optical center for aspheric lenses?

The optical center for an aspheric lens must be dropped 1 mm below the pupil center for every 2° of pantoscopic angle. This ensures the lens provides the correct vision correction.

How should the lens position be ordered according to the measurements?

The lens position should be ordered according to monocular PDs and the heights according to the final positioning of the markings, ensuring the lenses are correctly aligned with the wearer's eyes.