Soft contact lenses are usually characterised at room temperature, yet they function on the eye at body temperature, where their mechanics and optical performance can change. This study investigated whether soft silicone hydrogel lenses become more compliant in a physiological environment. Two silicone hydrogel materials (Definitive 74 and Unisil) were tested at 24 °C and 35 °C using uniaxial tensile and compression methods, with Ogden hyperelastic models fitted and finite element analysis performed on a realistic eye model. Both materials became more compliant at 35 °C, with Definitive 74 showing a larger modulus decrease (0.40 to 0.32 MPa) than Unisil (0.73 to 0.70 MPa). Finite element simulations indicated that these temperature-driven changes in compliance significantly affected refractive power, especially when the lens base curve exceeded the corneal radius by more than 5%. These findings demonstrate that soft silicone hydrogel lenses are indeed more compliant in a warm, hydrated environment, highlighting the need for physiologically relevant testing to inform design, fitting strategies, comfort, and vision outcomes.

Purpose: To investigate regional changes in tear film quality associated with orthokeratology (Ortho-K) lens wear using high-resolution spatial mapping and to evaluate the potential of artificial intelligence (AI) models in anticipating these changes. Methods: This study analysed tear film quality in 92 Ortho-K wearers divided into three groups based on lens wear duration (10–29 days, 30–90 days, and ≥91 days). Placido-based topographer measurement was used to generate regional tear film maps before and after treatment. A custom MATLAB pipeline enabled regional comparisons and statistical mapping. A feedforward neural network was trained to forecast local tear film quality using spatial data. Results: Single-value global mean metrics showed minimal changes in tear film quality across groups. However, regional mean mapping revealed significant mid-peripheral and peripheral deterioration over time, particularly in nasal and temporal corneal zones. These changes were often overlooked by global averaging and remained invisible through tear film breakup time (TBUT) measurements. The AI model predicted spatial tear quality with high accuracy (R ≥ 0.9 in testing), capturing nuanced regional variations. Conclusions: The regional analysis uncovers subtle, clinically relevant tear film disruptions caused by Ortho-K lens wear, particularly in peripheral areas. These insights challenge the adequacy of traditional single-value global mean assessments. The AI model demonstrates the potential for non-invasive, predictive evaluation of tear stability, supporting more personalised and effective Ortho-K care.

Blue-light filters now span spectacle, contact and intraocular lenses, but the term encompasses technologies with markedly different spectral characteristics and intended outcomes. This state-of-the-art narrative review synthesises peer-reviewed evidence on optical performance, digital eye strain, glare, photostress, sleep and circadian physiology, retinal phototoxicity, macular health, reported adverse effects and commercial translation. Near-clear spectacle filters preserve high-contrast acuity in most studies, but randomised and systematic reviews show no clinically meaningful average reduction in short-term digital eye strain. Some products reduce blue-colour contrast, particularly under low-contrast or low-light conditions, and adverse-event reporting is sparse. Studies of evening filters are heterogeneous: substantial amber attenuation can alter circadian light exposure, yet several trials have found no objective sleep benefit. Conventional visual outcomes with blue-filtering intraocular lenses are broadly comparable with ultraviolet-only lenses, although some individual studies report small mesopic colour or contrast disadvantages; long-term macular protection remains unresolved. Research on contact lenses is limited, typically short-term and often manufacturer-associated, and focuses on glare, photostress, scatter and perceived brightness rather than long-term health outcomes. Taken together, the evidence should be interpreted by filter spectrum and intended outcome, rather than treating blue-light filtering as a single intervention.

Objectives: This study aimed to determine whether eccentric gaze produces a regional, gaze-aligned redistribution of tear-film quality that is more apparent in spatial analysis than in whole-map summary measures. Methods: This was a secondary analysis of a previously acquired Medmont Meridia composite-topography dataset from 38 healthy participants, using only the Medmont data. Tear-film quality maps from the ahead, right, left, up, and down gaze were interpolated onto a common grid, aligned to a shared reference frame, and analysed using descriptive global measures, regional spatial mapping, and a threshold-based directional sector analysis. The threshold analysis used an operational cut-off of 0.35 to classify good-quality pixels, with lower values indicating better tear-film quality. Robustness was assessed by repeating the same analysis across nearby cut-offs from 0.30 to 0.40. As Placido-based topography measures reflection from the tear layer rather than the ocular surface itself, and as ocular rotation changes lid position and exposed ocular surface area, aligned comparisons were interpreted as comparisons of the exposed tear-film pattern rather than exact point-for-point anatomical tracking. Results: Global tear-film summary measures showed only modest variation with gaze direction, whereas spatial mapping revealed systematic regional redistribution of tear-film quality across eccentric gaze conditions. At the 0.35 operational threshold, the gaze-aligned good-pixel index was positive for right gaze (0.297 ± 0.200), left gaze (0.213 ± 0.174), up gaze (0.204 ± 0.219), and down gaze (0.308 ± 0.260). All four indices remained greater than zero after Holm correction (all pHolm < 0.001), and all remained greater than the matched ahead-gaze sector indices (all pHolm < 0.001). Threshold sensitivity analysis across cut-offs from 0.30 to 0.40 showed that the positive directional pattern was preserved for all gaze directions. Conclusions: Tear-film quality varies regionally with gaze direction, a pattern that was clearer in spatial maps and sector indices than in global summaries. Straight-ahead measurements may therefore provide an incomplete account of tear-film behaviour during eccentric gaze. As the analysis involved healthy participants and did not assess symptoms or diagnostic performance, the clinical relevance of this pattern requires validation in symptomatic populations.