| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2692949 | Contact Lens and Anterior Eye | 2015 | 5 Pages |
•Study assessed lens fit: centration, blink movement, lag and push-up recovery speed.•Experienced observers were variable in their estimations.•Subjective estimates used less range than objective measures & had lower precision.•Subjective estimates generally had poorer repeatability than objective measures.•Hence objective analysis useful for research and optimizing lens fit in practice.
PurposeTo assess the validity and repeatability of objective compared to subjective contact lens fit analysis.MethodsThirty-five subjects (aged 22.0 ± 3.0 years) wore two different soft contact lens designs. Four lens fit variables: centration, horizontal lag, post-blink movement in up-gaze and push-up recovery speed were assessed subjectively (four observers) and objectively from slit-lamp biomicroscopy captured images and video. The analysis was repeated a week later.ResultsThe average of the four experienced observers was compared to objective measures, but centration, movement on blink, lag and push-up recovery speed all varied significantly between them (p < 0.001). Horizontal lens centration was on average close to central as assessed both objectively and subjectively (p > 0.05). The 95% confidence interval of subjective repeatability was better than objective assessment (±0.128 mm versus ±0.168 mm, p = 0.417), but utilised only 78% of the objective range. Vertical centration assessed objectively showed a slight inferior decentration (0.371 ± 0.381 mm) with good inter- and intrasession repeatability (p > 0.05). Movement-on-blink was lower estimated subjectively than measured objectively (0.269 ± 0.179 mm versus 0.352 ± 0.355 mm; p = 0.035), but had better repeatability (±0.124 mm versus ±0.314 mm 95% confidence interval) unless correcting for the smaller range (47%). Horizontal lag was lower estimated subjectively (0.562 ± 0.259 mm) than measured objectively (0.708 ± 0.374 mm, p < 0.001), had poorer repeatability (±0.132 mm versus ±0.089 mm 95% confidence interval) and had a smaller range (63%). Subjective categorisation of push-up speed of recovery showed reasonable differentiation relative to objective measurement (p < 0.001).ConclusionsThe objective image analysis allows an accurate, reliable and repeatable assessment of soft contact lens fit characteristics, being a useful tool for research and optimisation of lens fit in clinical practice.
