Lenspeak – Taking A Leaf From Classification Of Diamonds !

Evolution of  intraocular lenses with a variety of mechanisms of action attempting to improve lens performance has resulted in complex and poorly understood terminology. There is a need for universally accepted nomenclature in order to communicate.  Mechanisms of action are confused with optical performance, the classic being the term EDOF or “extended depth of focus” whereby many ophthalmologists associate EDOF with less dysphotopsias. . The ANSI standard for EDOF lenses requires an implant to have intermediate vision (67cm) of 20/40 50% or more of recipients.  No mention is made of dysphotopsias..  The purpose of this initiative was to provide a systematic approach improving cognitive ease for all stakeholders and avoid misunderstanding. 

Short term working group from the European division of the American European Congress of Ophthalmic Surgery

The authors convened to consider current lens terminology and craft a systematic classification to ease understanding for all stakeholders: 1.patients, 2.ophthalmologists and 3.manufacturers.  Defining principles of a good nomenclature were considered. Nomenclature and classification used the following principles: simple, stable, uniform rules, room for further additions and simple language understandable by all stakeholders.  The component issues of lens behaviour were identified and differentiating terminology was crafted by the members of the committee.  A further ramification of this exercize was to provide industry a set of data collection criteria that would assist in categorising lenses going forward.

3 main components were identifid: 1. Range of focus, 2. Mechanisms of actions and 3.Dysphotopsias.  The committee acknowledged a number of variables influencing the above components but felt they could not be included.

Range of focus was classified using the following terms: Monofocal, Monofocal Plus, Increased range of Focus (IROF) and Full range of Focus (FROF).  Mechanism of action of the lens included Accommodation, Small aperture (true EDOF) Diffractive, Zonal Refractive, Combined and Other. Dysphtopsias were classified with the following terms: Glare, Halos, Starbursts, and Other (to include e.g. waxy vision syndrome).

A questionnair was devised to address parameters of which manufacturers will be invited to fill in future..  

Like the  4Cs of Color, Clarity, Cut and Carat devised by Shipley and employed by the Gemological Institute of America for classifying diamonds simplified a previous complex process; this Lenspeak classification and terminology should simplify understanding of lens performance and enable better communication amongst stakeholders, in particular patients. Enthusiasm and adoption of the terminology  over the last year has been encouraging.