There are several steps to eyewear dispensing, all of which require the careful attention of an Eye Care Practitioner (ECP). After refraction, the process starts with understanding the needs of the consumer and picking the spectacle frames that are suitable for them. A series of manual measurements are taken which check how the frame sits on the consumer’s face. An order is placed, the prescribed lenses are fitted into the chosen frames and lastly, minor adjustments will be made to ensure the spectacles fit comfortably.
This process of dispensing requires knowledge of the prescription, lenses and dispensing skills to ensure a perfect fit. This process is highly dependent on the skills and knowledge of the ECP, therefore is subject to the occasional human error. To minimise such errors, manufacturers are looking into how the dispensing process can be improved. One development is the pupilometer, a machine used to measure the pupillary distance in order to determine the optical centre of the lenses instead of manual measurement. A pupilometer is also used as a pupil response monitor, measuring the amount of pupil dilation in response to visual stimuli. The use of pupilometers is not widely practiced in the industry due to the limited measurements it performs, and these measurements are still mostly carried out manually.
Pupillary distance measurement using pupilometer
Source: General Optical Council
New technology in eyewear dispensing
As more developments unfold for spectacle lenses, the dispensing process is becoming more complex and often comes at an additional cost to be borne by the consumer. Lenses are now offered with customisation and precision levels that were previously not thought possible. With advancements in technology, consumers too, naturally raise their expectations in terms of quality. The details of these technological advancements and differences between brands are often behind the scenes and too technical for consumers to understand, therefore going digital and showcasing these machines becomes one way to justify the higher price consumers are paying.
Two types of digital dispensing technology today are free standing units and tablet-based systems. Examples of free-standing units are Visioffice by Essilor and iTerminal by Carl Zeiss, which are usually more costly due to their high functionality, being able to take more comprehensive measurements. Spectacle lenses which require such comprehensive measurements are generally more expensive and with these high-tech systems in-store taking measurements, the higher price is justified.
On the other hand, tablet-based systems, such as Hoya Spectangle and M’eye Fit by Essilor are the basic systems for fitting digitally surfaced lenses. Spectacle lenses fitted using such systems tend to be lower priced.
Free standing unit: Essilor Visoffice & Carl Zeiss iTerminal
Source: www.essilor.com and www.zeiss.com
Digital eyewear dispensing becoming basic
Essentially, these systems perform the basic measurements, such as pupillary distance, segment height for progressive lenses, vertex distance, panoramic angle and pantoscopic tilt. Visualising how the spectacles look on the face is a common problem among spectacles buyers, so these systems often incorporate a digital photography function capturing how the consumer looks wearing the spectacles. Other than the basic measurements, some more comprehensive systems also perform technical measurements, such as eye rotation and visual habits. These measurements are called “position of wear”.
While the refraction position is the matching of the prescription with the consumers’ visual needs, “position of wear” is a set of measurements that allow the laboratory to make alterations to the lens design to match the consumer’s prescription needs. Both measurements are equally important in maximising visual quality.
Benefits of these systems are that precision and accuracy are enhanced, as they take more precise readings as compared to the traditional method of measurement. Repeatability is also possible among different ECPs in a practice as everything is digitally measured instead of reliant on individual skills, minimising human error. Despite the benefits, education is necessary for the consumer to understand the higher price they are paying. Manufacturers are increasingly putting in efforts to market digital surface lenses but little was done on the system performing such measurements.
As marketing efforts become more successful in the future, it is almost impossible for a practitioner to not own a lens fitting system. Practitioners who think they can rely on existing skill sets will see themselves losing competitive advantage over the years when consumers stop coming back as they are not keeping up with the current technology.