OBJECTIVE: To evaluate the impact of short-term scleral lens (SL) wear on anterior chamber (AC) dimension and central corneal thickness (CCT) in healthy Chinese people.
METHODS: This is a prospective, daily wear study. Eligible participants were dispensed SLs to correct refractive errors. Anterior segment (AS) parameters were measured by AS optical coherence tomography (AS-OCT) before, during, and after 2 and 4 hours of lens wear. Repeated-measures analysis of variance (ANOVA) was used to analyze the changes in AS parameters over time.
RESULTS: Twelve subjects (10 females and 2 males) with a mean age of 25.3 ± 3.8 years (ranging from 21 to 34 years) were recruited. The AC parameters, including anterior chamber depth (ACD) from the endothelium (endo-ACD), angle opening distance at 500 μm (AOD500), and trabecular-iris space area at 500 μm (TISA500), significantly decreased after wearing SLs for 4 hours (P<0.05). CCT increased by 12 μm (2.29 %) after wearing SLs for 4 hours (P=0.013).
CONCLUSIONS: This study suggests that SL wear has a significant impact on AS dimensions in patients with healthy corneas in the short term with SL in situ, but tend to recover quickly after SL removal. Further research is needed to determine whether the change in AS dimensions during SL wear affects aqueous humor (AH) outflow and causes changes in intraocular pressure (IOP).

OBJECTIVE: To quantify the impact of varying central fluid reservoir depth, lens thickness/mass and the addition of a peripheral fenestration upon scleral lens centration.
METHODS: Ten young, healthy adults participated in a series of repeated-measures experiments involving short-term (90 min) open eye scleral lens wear. Scleral lens parameters (material, back optic zone radius, diameter, back vertex power and landing zone) were controlled across all experiments, and the central fluid reservoir depth (ranging from 144 to 726 μm), lens thickness (ranging from 150 to 1200 μm), lens mass (101-241 mg) and lens design (with or without a single 0.3 mm peripheral fenestration) were altered systematically. Scleral lens decentration was quantified using over-topography maps.
RESULTS: On average, scleral lens centration varied by <0.10 mm over 90 min of wear. Medium and high initial fluid reservoir conditions resulted in 0.17 mm more temporal and 0.55 mm more inferior lens decentration, compared to the low fluid reservoir depth (p < 0.001). Changes in lens thickness or the addition of a peripheral fenestration did not cause clinically significant changes in centration (<0.10 mm on average) when controlling for fluid reservoir depth. Central fluid reservoir depth was the best predictor of horizontal and vertical lens decentration, explaining 62-73% of the observed variation, compared to 40-44% for lens thickness and mass.
CONCLUSIONS: Scleral lens decentration remained relatively stable over 90 min of lens wear. A greater initial central fluid reservoir depth resulted in significantly more lens decentration, particularly inferiorly. Large variations in lens thickness, mass or the addition of a single peripheral fenestration did not substantially affect lens centration.

Purpose: Dry eye disease (DED) is a multifactorial condition significantly impacting patients\' quality of life (QoL). This study aims to present a case series highlighting the effectiveness of customized scleral lenses in managing severe DED and improving patient outcomes. Methods: This case series includes three patients with severe DED refractory to conventional treatments. Customized scleral lenses were fitted for each patient, and clinical outcomes were evaluated over a period of two months. Assessments included best-corrected visual acuity (BCVA), slit-lamp examination findings, and corneal National Eye Institute (NEI) scores. Results: All three patients demonstrated significant improvements in BCVA, reductions in ocular symptoms, and enhanced ocular surface health. Patient 1, with secondary Sjögren\'s syndrome and suspected mucous membrane pemphigoid, showed resolution of conjunctival hyperemia and epithelial defects. Patient 2, with graft versus host disease, exhibited resolution of punctate keratitis and the absence of thread mucus. Patient 3, post-oncologic surgery, achieved complete resolution of keratoconjunctivitis sicca and the restoration of vision. Conclusions: Customized scleral lenses are a useful therapeutic option for severe DED, providing significant symptomatic relief and enhancing patients\' quality of life. Their use should be considered in refractory cases to optimize ocular surface health and visual outcomes.

OBJECTIVE: To investigate whether the midday removal and re-application of scleral lenses (SL) influences fluid reservoir (FR) thickness, pre-lens tear film quality and visual acuity.
METHODS: Two clinical experiments were conducted. A total of 49 keratoconic eyes were evaluated for Part1(tear film and visual acuity analysis) and 12 keratoconic eyes for Part2 (FR thickness analysis). All subjects were wearing 16.4 mm SL for more than 12-months. Tear Film Surface Quality (TFSQ) was evaluated with Medmont E300 at more than 120 min of SL wear, 10 min after SL removal (pre-corneal TFSQ) and 5 min after re-apply the same SL. High and Low Contrast Visual Acuity (HCVA and LCVA) were also assessed with the SL on eye (before and after re-application). For Part2, Anterior OCT (MOptim MOcean4000, China) measurements were taken with and without the SL (at the same time points of Part1) and three outcomes were evaluated: FR thickness, SL thickness (control measurement) and corneal thickness.
RESULTS: Removing and re-applying a SL had a statistically significant positive impact on TFSQ, with an improvement from 0.26 ± 011 to 0.16 ± 0.08 (p = 0.001). This was accompanied by a statistically significant improvement in LogMAR HCVA (from 0.10 ± 0.09 to 0.08 ± 0.08, p < 0.001) and LCVA (from 0.39 ± 0.13 to 0.36 ± 0.13, p < 0.001). Regarding Part2 of the study, a statistically significant increase in FR thickness was observed after SL re-application (from 223.64 ± 48.08 µm to 267.81 ± 80.03 µm, p = 0.007). No changes in corneal thickness were observed.
CONCLUSIONS: Midday removal and re-application of a scleral lens positively impacted pre-lens tear film surface quality, although the observed improvement in visual acuity does not constitute a clinically significant change. Clinicians should consider that removing and reapplying a scleral lens may result in an overestimation of the fluid reservoir thickness, which could affect clinical assessments and treatment decisions.

OBJECTIVE: Midday fogging (MDF) occurs when particulate material accumulates in the fluid reservoir (FR) beneath scleral lenses (SL), and its impact on epithelial cells is unknown. This study examines the in vitro pro-inflammatory effect of the FR on human corneal epithelial cells in varying degrees of MDF.
METHODS: Normal SL neophytes were recruited to wear SL 8 h daily for 4 days. Following 8 h on days 1 and 4, optical coherence tomography (OCT) images were acquired for MDF quantification using ImageJ, and the FR was collected. FR samples from the same eye were later pooled, diluted 2-fold and applied on human telomerase-immortalized corneal epithelial (hTCEpi) cells cultured on Terasaki microwell plates. Tumor necrosis factor (TNF)-α and culture media were used as positive and negative controls, respectively. After a 30-minute treatment, the nuclear factor-kappa B (NF-κB) pathway was measured by NF-κB-p65 immunofluorescence and images were analyzed with ImageJ. Pearson\'s correlation was conducted to determine the association between median nuclear fluorescence and MDF.
RESULTS: Fourteen FR samples with a mean volume of 22 ± 16 µl were tested. Mean MDF severity following 8 h of SL wear was 25 ± 17 units (range 7 - 64). The median nuclear fluorescence (NF-κB-p65 translocation) in cultured hTCEpi cells ranged from 31.43 to 45.16 while the negative and positive controls were 44.71 ± 1.72 and 108.77 ± 68.38, respectively. Although a potential positive trend between MDF and median nuclear fluorescence was observed, Pearson\'s correlation analysis revealed no significant association (r = +0.48, P = 0.09).
CONCLUSIONS: The results suggest that the FR can trigger NF-κB-p65 translocation in hTCEpi cells, which may be associated with MDF severity. This study introduces the use of Terasaki microwell plates for immunofluorescence studies of the FR. The technique is simple, minimizes sample usage, and does not require expensive instrumentation.

OBJECTIVE: The fit and optical performance of a scleral lens is affected by the alignment of the landing zone with the underlying ocular surface. The aim of this research was to quantify the effect of landing zone toricity upon scleral lens fitting characteristics (rotation and decentration) and optics (lens flexure) during short-term wear.
METHODS: Scleral lenses with nominal landing zone toricities of 0, 100, 150 and 200 μm were worn in a randomised order by 10 young healthy participants (mean [SD] 24 [7] years) for 30 min, with other lens parameters held constant. Scleral toricity was quantified using a corneo-scleral profilometer, and lens flexure, rotation, and decentration were quantified using over-topography during lens wear. Repeated measures analyses were conducted as a function of landing zone toricity and residual scleral toricity (the difference between scleral and lens toricity) for eyes with \'low\' magnitude scleral toricity (mean: 96 μm) and \'high\' magnitude scleral toricity (mean: 319 μm).
RESULTS: Toric landing zones significantly reduced lens flexure (by 0.37 [0.21] D, p < 0.05) and lens rotation (by 20 [24]°, p < 0.05) compared with a spherical landing zone. Horizontal and vertical lens decentration did not vary significantly with landing zone toricity. These trends for flexure, rotation, and decentration were also observed for eyes with \'low\' and \'high\' magnitude scleral toricity as a function of residual scleral toricity.
CONCLUSIONS: Landing zones with 100-200 μm toricity significantly reduced lens flexure (by ~62%) and rotation (by ~77%) but not horizontal or vertical lens decentration, compared with a spherical landing zone, when controlling for other confounding variables. The incorporation of a toric landing zone, even for eyes with lower magnitude scleral toricity (~100 μm), may be beneficial, particularly for front surface optical designs.

OBJECTIVE: This study describes efficiency of diagnostic, image-based, and impression-based fitting methods by eye care providers who prescribe scleral lenses (SL) for patients with keratoconus.
METHODS: An electronic survey was distributed to eye care providers with an interest in SL fitting. Demographic data including practice modality, country of residence, and fitting volume were collected. Efficiency of each fitting method (diagnostic, image, and impression-guided) was queried including time required for initial evaluation, number of lenses ordered, and number of office visits required. Practitioners with access to image and impression-based technology were also asked time required to acquire data and to estimate the percentage of time a lens could be manufactured from the initial images or impressions.
RESULTS: 423 practitioners who prescribe SL for patients with keratoconus reported completing a median [IQR] 100 [280] SL fittings. There was no difference in the median time required for initial evaluation (30 min; p = 0.5) or median number of lenses ordered during the fitting process (2 lenses; p = 0.2) between diagnostic, image-based, or impression-based SL fitting methods. Median time to acquire initial images was 10 [7] minutes and 15 [10] minutes to obtain impressions. Images obtained were adequate to order an initial lens 80 [45]% of the time while initial impressions were adequate 90 [40]%.
CONCLUSIONS: In this study, practitioner-reported efficiency of SL fitting was similar between diagnostic, image-based and impression-based methods for patients with keratoconus.

OBJECTIVE: To investigate the short-term effect of scleral lens (SL) on corneal curvature and corneal oedema in Pellucid Marginal Degeneration (PMD) eyes.
METHODS: Corneal anterior, posterior curvature and corneal thickness were measured in 14 eyes of 14 PMD participants with Schiempflug imaging at different corneal diameters and meridians at baseline and after 6 h of SL wear.
RESULTS: There was a significant flattening (up to 0.26 mm) of the anterior corneal curvature noted in the inferotemporal quadrant (from 210 to 255 degree at 2 mm, 8 mm and 10 mm corneal diameter), inferonasal quadrant (from 285 to 345 degree at 6 mm and 8 mm corneal diameter), and inferiorly at 2 mm and 10 mm corneal diameter (p < 0.05). Similarly, posterior corneal curvature showed statistically significant steepening mostly in inferotemporal quadrants (from 195 to 255 degree from 4 mm to 8 mm corneal diameter) and inferonasally at 2 mm and 4 mm corneal diameter (p < 0.05). A statistically significant increase in the corneal thickness noted in different corneal diameters with corneal oedema ranging from 2.10 % to 4.00 % after 6 h of SL wear. A gradual increase in corneal oedema was noted form centre to periphery. The baseline central fluid reservoir thickness (FRT) was 341.07 ± 139.8 which reduced to 276.71 ± 114.32 µm after 6 h of lens wear. No significant correlation was noted between corneal oedema with different parameters like initial and final FRT, change in anterior and posterior corneal curvature, and lens thickness (p > 0.05).
CONCLUSIONS: Short-term SL wear induced a clinically acceptable range of corneal oedema. A clinically significant flattening in anterior curvature and minimal steepening in posterior curvature were noted. Practitioners should be careful while measuring corneal parameters in PMD eyes wearing SL, as these alterations can provide false impression of disease progression.

Professor George Smelser was a scientist who played a crucial role in advancing the understanding of the anatomical and physiological changes within the cornea during contact lens wear. In a series of unique experiments conducted in the early 1950s, using both humans and animal models, his research team provided the first conclusive evidence that contact lenses impaired the delivery of atmospheric oxygen to the cornea, resulting in an excess of lactate within the cornea and a subsequent ingress of water, leading to corneal oedema and disturbed vision (Sattler\'s veil). This historical note reviews the career of George Smelser, with particular emphasis on his contributions to understanding the importance of atmospheric oxygen in maintaining corneal homeostasis.

OBJECTIVE: To analyze the visual quality of a new multifocal scleral lens with a customized decentred optic zone compared to a conventional design by measuring visual acuity, contrast sensitivity function, stereopsis, subjective vision and comfort after one month of wear.
METHODS: Nineteen presbyopic subjects were fitted with two multifocal scleral lens designs: a conventional multifocal and a customized decentred optical zone design. All subjects wore both scleral lens designs for one month with a two-week washout period. The main variables evaluated included high and low-contrast visual acuity under photopic and mesopic light conditions, binocular defocus curves, contrast sensitivity function and a visual analogue scale (VAS) for subjective vision and comfort.
RESULTS: Comparing the two scleral lens designs, statistically significant differences in visual acuity were found, highlighting the improvement in more than one chart line (6 letters) for low contrast near tests under photopic light conditions with the decentred optics lens design. VAS questionnaire scores also showed a significant improvement in distance and overall subjective vision with the decentred optics lenses. Contrast sensitivity function showed an improvement with decentred multifocal lenses at all spatial frequencies measured, being statistically significant for 12 cycles per degree. No differences in stereoacuity were found.
CONCLUSIONS: Multifocal scleral lenses with a customized decentred optical zone proved to be a promising refractive correction in presbyopic subjects after one month of wear, offering good comfort and visual quality under photopic and mesopic light conditions.