Progressive addition lenses (PALs) are traditionally described using a three-zone model: distance, intermediate, and near. While clinically convenient, this framework introduces a conceptual error by implying the existence of a discrete intermediate region with defined optical function.
In reality, PALs exhibit a continuous distribution of power and astigmatism, with no true boundaries between functional states.
Find out more when you join Dr Grant Hannaford from the Academy of Advanced Ophthalmic Optics (AAOO) for a free one-hour webinar titled, ‘Reframing the intermediate zone in progressive addition lenses: A functional field perspective’ on 29 May 2026.
Participants will be able to reinterpret patient performance and complaints… improving prescribing accuracy and patient outcomes
This lecture will explore early presbyopia and behaviours that are commonly misinterpreted as evidence of a functional intermediate corridor, reinforcing the persistence of the three-zone model.
Using power distribution analysis, gaze-dependent viewing geometry, and accommodative considerations, the session will redefine intermediate vision as an emergent property of the optical field rather than a spatially fixed region. It will explore clinical implications, including misinterpretation of adaptation, inappropriate lens design selection, and limitations in patient communication. The discussion will align practitioner understanding with contemporary freeform design principles, emphasising continuous optimisation over zone-based thinking.
Participants will be able to reinterpret patient performance and complaints using a gaze-dependent, accommodative model of lens function, improving prescribing accuracy and patient outcomes.
Register Now
The free webinar on the topic of progressives will be offered at two different times for clinicians:
Session 1: 12.00 noon Sydney Time
Session 2: 6.00pm Sydney Time
Sessions are identical – choose the one that suits your time zone and register here.
The webinars are accredited for one hour of CPD.
About the Speaker
Dr Grant Hannaford DOphSc, BSc, BA(Hons), FBDO SLD (Hons) is the co-founder and Director of AAOO and co-owns a private independent optometry practice Hannaford Eyewear which was awarded the 2022 and 2024 Australian Small Business Champion..
A physicist, lens designer and qualified optical dispenser, Dr Hannaford is at the forefront of ophthalmic optics in Australia and internationally after being named the 2022 Silmo IOA International Optician of the Year.
He is a Fellow of the Association of British Dispensing Opticians and the Australasian Dispensing Opticians Association. He is also an adjunct lecturer at the School of Optometry and Vision Science UNSW and the Save Sight Institute USYD.
Dr Hannaford completed his doctoral candidacy in 2025 at the School of Life and Health Sciences at Aston University, Birmingham England, researching emmetropisation and ocular biometric development in children.