winter 2025



SOFT LENS FITTING

The latest from the American Academy of Optometry Meeting & a Look Into the Future



Crystal Ball Gazing



debarun dutta




The annual meeting of the American Academy of Optometry in Indianapolis (IN, USA) in November 2024 brought together thousands of optometrists, educators, scientists and exhibitors to exchange knowledge and explore the future of our clinical profession.


Mismatch


I was fortunate to attend this event and present our latest research on soft contact lens sagittal depth (CL-SAG), as well as soft lens fitting to varying ocular sagittal heights (OC-SAGs), in collaboration with Eef van der Worp (see figures 1 & 2).






Figure 1: OC-SAG value bell curve of eyes in the study.






Figure 2: CL-SAG values of ‘steep,’ ‘median’ and ‘flat’ lenses used in the study.




Our findings showed that mismatching the CL-SAG and the OC-SAG results in an inappropriate lens fit. Specifically, fitting high–CL-SAG lenses to low–OC-SAG eyes and vice versa leads to a poor fit. As we know, a poor fit may be associated with lens discomfort, dissatisfaction or significant adverse reactions such as corneal infiltrative events.


Dropouts & Lens Fit


Another presentation by James Chung and Melissa Bailey revealed that patients with presbyopia who drop out of contact lens wear have an OC-SAG that is different from that of successful presbyopic contact lens wearers. Melissa, Eef and their colleagues also presented a poster indicating that soft contact lens movement with a blink may not be a strong indicator of relative OC-SAG and lens fitting.


These findings, coupled with previously published research, suggest that achieving a 'successful' soft contact lens fit for all patients remains a challenge, even for our regular spherical or toric lens wearers. A good lens fit is crucial for prolonged contact lens wear, maximum comfort and patient confidence. However, one-third of patients show signs of dissatisfaction within three months of starting contact lens wear, with variations depending on region and lens type.



Closing Remarks


As research continues, I am confident that we will gain a deeper understanding of CL-SAG and contact lens comfort, leading to better lens designs and tools to gauge lens fit beyond subjective methods such as post-blink movement and the push-up test. With limited soft contact lens parameters available to eye care practitioners, we need more options to fit all eye types.


The one-size-fits-all approach may fit 70-80% of the healthy population advanced technologies such as artificial intelligence (AI)-assisted lens fitting based on topography, ocular surface thermography, conjunctival vasculature beneath the lens, or simply fitting soft lenses based on OC-SAG (and diameter) rather than the base curve, could improve fit and comfort for our patients.







Poster American Academy of Optometry #92 - Indianapolis (US) November 2024