Longitudinal changes in Langerhans cell density of the cornea and conjunctiva in contact lens-induced dry eye

Does orthokeratology contact lens wear suppress the immune cell response in the human corneal epithelium, while soft contact lens wear enhances it?

BACKGROUND

Orthokeratology (OK) contact lenses are increasingly prescribed for myopia control but their impact on corneal epithelial immune cells (CEIC) is unclear. This study compares CEIC in OK wearers to soft contact lens (SCL) wearers and non-wearers.

METHODS

In vivo confocal microscope images at the corneal central and mid-peripheral subbasal level were evaluated in 18 OK wearers, 18 SCL wearers and 18 non-wearers (mean age 27.6±8.0 years; 65% female). Corneal epithelial immune cell density was manually quantified and morphology was graded using a published system. Statistical significances (p<0.05) were examined using generalised estimating equations.

RESULTS

Corneal epithelial immune cell density in OK wearers was lower than in SCL wearers (p=0.03) at the central cornea, but not at the mid-periphery. Compared to SCL wearers, OK wearers had smaller cell bodies, with fewer participants displaying CEIC with dendrites, long and thick dendrites at both corneal locations (p<0.001). Orthokeratology wearers also had smaller CEIC bodies (p=0.01) and fewer participants had CEIC with dendrites (p=0.01) than non-wearers at both locations. Contrarily, SCL wearers had larger CEIC bodies, with a greater proportion of SCL wearers displaying CEIC with dendrites, long and thick dendrites compared to non-wearers (p≤0.04) at both locations. Corneal epithelial immune cell density was higher at the central cornea than at mid-periphery in SCL wearers (p<0.001) and non-wearers (p=0.01), but not in OK wearers (p=0.26).

CONCLUSIONS

In long-term OK lens wear, immune cells observed in the corneal epithelium are fewer in number and are less likely to present with dendrites, suggesting a suppressed CEIC response in OK lens wear which should be investigated further.

The association between corneal immune cell dynamics and comfort in silicone hydrogel contact lens wearers

PURPOSE

To study the association between corneal immune cell dynamics and contact lens (CL) comfort, as well as tear film inflammatory mediators in established CL wearers.

METHODS

A prospective, cross-sectional study including existing CL wearers was conducted. Symptoms were assessed with a comfort visual analog scale (VAS) and the Contact Lens Dry Eye Questionnaire-8. In-vivo corneal confocal microscopy was used to track immune cell dynamics over 3 timepoints at 5-minute intervals. Trajectory speed was calculated as the total length travelled by cells divided by time; displacement speed as the straight-line distance between the start and end positions of a cell divided by time; and persistence ratio as the ratio of displacement speed and trajectory speed. Measurements were performed for 1-3 cells per participant, and the minimum, maximum, and average values were analyzed. Tear film samples were collected to assess matrix metalloproteinase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1, and the MMP-9/TIMP-1 ratio. Correlations between immune cell dynamics, symptoms, and tear inflammatory mediators, were analyzed.

RESULTS

Nineteen CL wearers (4 men and 15 women) aged 30 ± 5 years were included. Participants wore silicone hydrogel CLs for 8-10 h before clinical assessment. There was a significant association between comfort VAS and the maximum (rho = 0.533; p = 0.019) and average (rho = 0.506; p = 0.027) values of immune cell displacement speed. The concentration of MMP-9 was associated with the minimum value of trajectory speed (rho = 0.621; p = 0.031). Finally, the MMP-9/TIMP-1 ratio was associated with the maximum value of trajectory speed (rho = -0.717; p = 0.030), and the maximum (rho = -0.720; p = 0.008) and average (rho = -0.678; p = 0.015) values of displacement speed.

CONCLUSION

Corneal immune cell dynamics is related to sensations of discomfort in silicone hydrogel CL wearers, with cell speed possibly being regulated by inflammatory mediators assessed from the tear film. These observations may aid in understanding the mechanisms underlying the discomfort response.

Raman spectroscopy to investigate early biochemical alterations in human tears caused by contact lenses

CLINICAL RELEVANCE

The interaction between contact lenses and tear film plays a critical role in lens biocompatibility and can influence discomfort during wear. Early detection of biochemical changes is important for improving ocular surface health, preventing complications, and developing advanced lens materials to enhance long-term comfort.

BACKGROUND

The pursuit of biocompatible lens materials requires a thorough understanding of their interaction with tear environment. The aim of this study is to evaluate different approaches to investigate early alterations in tear biomolecular profiles induced by lens wear.

METHODS

Two participants wore different CLs and underwent ocular analysis before CL insertion (T0), after 2-hour wear (T2), and two hours after removing the CL (T4), evaluating non-invasive tear break-up time (NIBUT), tear meniscus height (TMH), and osmolarity. Forty CLs were used. At the same time points, tears were collected and analysed by Raman spectroscopy.

RESULTS

Tear film stability, as measured by NIBUT, decreased post-lens wear (T0 vs T2, p = 0.034 and 0.025 for S1 and S2, respectively) but showed recovery within 2 hours (T0 vs T4, p > 0.05 for both S1 and S2), while TMH and osmolarity remained unchanged (T0 vs T2 vs T4, p > 0.05 for both S1 and S2). Raman spectroscopy highlighted notable changes in the biomolecular profile of tears after lens wear, particularly in the 2700-3200 cm-1 spectral window related to C-H stretching, which is sensitive to CH, CH2 and CH3 groups, their functional chemistry group, and the surrounding microenvironment.

CONCLUSIONS

Contact lens wear induces subtle biochemical, subclinical alterations in tears that can be detected early by Raman spectroscopy. The method is promising for analysing the subject-specific responses to lenses, also with possible individual variability in the timing of these changes. In addition, this approach can provide insights for designing biocompatible materials and for the early detection of subclinical biomarkers.

In vivo confocal microscopy findings about ocular surface recovery in patients following pterygium excision combined with conjunctival autograft

PURPOSE

To study cellular and neural changes around the donor and recipient areas after pterygium excision combined with autologous conjunctival transplantation using corneal confocal microscopy, we evaluated the postoperative impact of this surgical procedure.

METHODS

Patients with primary pterygium located on the nasal side who visited the Department of Ophthalmology of Wuxi Second People's Hospital between April and August 2023 were enrolled. Age-matched healthy eyes were included as the control group. IVCM was performed in the affected eyes, 6 months after pterygium excision. The images of the central conjunctival cells in the recipient and donor areas, the cells of each layer of the cornea around the recipient and donor area (around 2 mm from the nasal and upper corneal margins), and the structures of the corneal margins were recorded in the affected eyes and statistically compared with the corresponding areas in the control eyes.

RESULTS

Seventeen eyes of 14 patients with primary pterygium located on the nasal side (mean 64 ± 8.74 years old), and 17 eyes of nine patients as age-matched normal controls were included. Compared with those of normal eyes, the density of corneal pterygoid epithelium around the recipient area (5104 ± 599 cells/mm2 vs. 5700 ± 515 cells/mm2, P < 0.01) and the central conjunctival epithelial cells in the recipient areas (3984 ± 453 cells/mm2 vs. 4834 ± 244 cells/mm2, P < 0.01) were significantly lower 6 months postoperatively. However, the superficial stromal, deep stromal, and endothelial cell densities around the recipient area exhibited no significant differences (P > 0.05). Highly illuminated basal cells were visible at the nasal corneal margin, with an irregular intersection of fibrous tissue with corneal epithelial cells. More dendritic Langerhans cell infiltration was seen in the junctional area. Compared with those in the normal eyes, the densities of the corneal pterygoid epithelium (4896 ± 428 cells/mm2 vs. 5557 ± 367 cells/mm2, P < 0.01), deep stromal cells (337 ± 65 cells/mm2 vs. 419 ± 39 cells/mm2, P < 0.01), endothelial cells (2305 ± 170 cells/mm2 vs. 2547 ± 212 cells/mm2, P < 0.01) around the donor area and the central conjunctival epithelial cells (3700 ± 446 cells/mm2 vs. 4282 ± 272 cells/mm2, P < 0.01) in the donor area were significantly lower 6 months postoperatively. However, no significant differences were observed in superficial stromal cell density (P > 0.05). A slight wavy interfacial intersection was visible on the superior corneal margin, with some of the highlighted basal cells visible.

CONCLUSIONS

Pterygium excision combined with autologous conjunctival transplantation with corneal stem cells can better promote the repair of most corneal cells around the recipient area and fence-like structures of the corneal rim 6 months postoperatively, but there may be some damage to the corneal conjunctival structures around the donor area.

2024 Charles F. Prentice Medal award lecture: Moments of inspiration

In this Prentice Medal Award lecture, I shall recount my career in vision science in the context of three types of inspiration-"being inspired," "personal inspiration," and "inspiring others." My research has derived inspiration from a variety of sources, such as contemporary and historical research doyens in the ophthalmic field and beyond, artists, Greek philosophers, and abstract constructs such as principles and adages. A given moment of inspiration can range from being a profound experience to a subtle realization during a quiet moment of reflection. Here I shall recount the primary research domains of vision science that have defined my academic career in the context of the three types of inspiration defined above. These research domains are ophthalmic markers of diabetic neuropathy, ocular response to contact lens wear, contact lens-induced parainflammation, contact lens-associated microbial keratitis, grading scales for contact lens complications, contact lens prescribing surveys, material properties of contact lenses, contact lens compliance, history of contact lenses, ocular thermography, and ophthalmic bibliometrics. The notions of "being inspired" and "personal inspiration" are necessarily subjective, although I have endeavored to present them here in a scientific context. Conversely, the notion of "inspiring others" can be objectively gauged, at least in part, by counting article citations or the number of times articles are read online or downloaded from a journal website. In conclusion, my research in the vision sciences has been inspired by others, derived from personal ideas, and perhaps in turn has inspired others.

Solitary Langerhans Cell Histiocytosis of the Palpebral Conjunctiva Presenting as Leukoplakia: Case and Review of Literature

A 69-year-old male presented with a superior palpebral conjunctival white leukoplakic lesion. Excisional biopsy showed Langerhans cell histiocytosis. Positron emission tomography scanning revealed no lesions beyond this site. Native Langerhans cells are known to exist in the conjunctiva, yet only a few cases in the literature have described Langerhans cell histiocytosis of the conjunctiva, mostly in children. Conjunctival Langerhans cell histiocytosis has rarely been reported in an adult as leukoplakia. The authors advocate excisional biopsy for palpebral conjunctival Langerhans cell histiocytosis in older patients if the morbidity of closure is minimal, in addition to surveillance for multifocal disease.

Persistence of Contact Lens-Induced Corneal Parainflammation Following Lens Removal

Purpose

Contact lens wear induces corneal parainflammation involving increased immune cell numbers after 24 hours' (CD11c+, Lyz2+, γδ-T cells) and six days' (Ly6G+ cells) wear. We investigated the time course of onset and resolution of these responses.

Methods

LysMcre or C57BL/6J mice were fitted with a contact lens (four to 48 hours). Contralateral eyes did not wear lenses. After lens removal, Lyz2+, MHC-II+ or Ly6G+ cells were examined by quantitative imaging. RT-qPCR determined cytokine gene expression.

Results

Lens wear for 24 hours increased corneal Lyz2+ cells versus contralateral eyes approximately two-fold. Corneas remained free of visible pathology. The Lyz2+ response was not observed after four or 12 hours' wear, nor after 12 hours' wear plus 12 hours' no wear. Lens removal after 24 hours' wear further increased Lyz2+ cells (∼48% after one day), which persisted for four days, returning to baseline by seven days. Lyz2+ cells in contralateral eyes remained at baseline. MHC-II+ cells showed a similar response but without increasing after lens removal. Lens wear for 48 hours showed reduced Lyz2+ cells versus 24 hours' wear with one day discontinuation, correlating with reduced IL-1β and IL-18 gene expression. Lens wear for 24 hours did not induce Ly6G+ responses six days after removal.

Conclusions

Lens-induced corneal parainflammation involving Lyz2+ cells requires 24 hours' wear but persists after lens discontinuation, requiring seven days for reversal. Lens wear for 48 hours may suppress initial Lyz2+ cell and cytokine responses. The significance of parainflammation during and after lens wear remains to be determined.

Efficacy of 2% Hydroxypropyl Methylcellulose and Bandage Contact Lens for the Management of Dry Eye Disease after Cataract Surgery

Objectives

To investigate the effect of 2% hydroxypropyl methylcellulose (HPMC) and bandage contact lens (BCL) on dry eye disease after cataract surgery.

Methods

This prospective randomized controlled trial included 63 eyes which were divided into the balanced salt solution (BSS), HPMC, BCL, and combined HPMC and BCL (H&B) groups. The Ocular Surface Disease Index (OSDI), tear meniscus height (TMH), and average tear break-up time were measured before cataract surgery and 30 days postoperatively. Differences in corneal nerve fiber (CNF) and dendritic cell (DC) density in various directions were evaluated and compared. The CNFs and DCs in central and infratemporal directions were observed using in vivo confocal microscopy. Data were evaluated using the Kruskal-Wallis rank-sum test and analysis of variance.

Results

The differences in variations in OSDI and TMH after cataract surgery between the four groups were statistically significant (P < 0.05). The postoperative OSDI of the HPMC group decreased compared with their preoperative OSDI. A statistically significant difference in the variations of OSDI score was observed between the HPMC and other groups (P < 0.05). The postoperative variations in TMH in the HPMC group were significantly higher than those observed preoperatively and significantly differed between HPMC and BCL groups and between BCL and H&B groups (P < 0.05). Postoperatively, the density of corneal DCs decreased in BSS and HPMC groups and increased in BCL and H&B groups (P < 0.001).

Conclusions

The application of 2% HPMC in cataract surgery has a certain effect on managing dry eye after cataract surgery. Although the use of BCLs after cataract surgery has some benefits, it may cause mild ocular surface inflammation. Nevertheless, using 2% HPMC with BCLs in the perioperative phase of cataract surgery can alleviate the subjective discomfort of patients and can safely and effectively replace eye patch after cataract surgery.

Contact lens-induced corneal parainflammation involving Ly6G+ cell infiltration requires IL-17A and γδ T cells

PURPOSE

Previously, using a murine model, we reported that contact lens (CL) wear induced corneal parainflammation involving CD11c+ cells after 24 h and Ly6G+ cells (neutrophils) after 5-6 days. Here, we investigated the role of IL-17 and γδ T cells in the CL-induced neutrophil response.

METHODS

CL-wearing C57BL/6 wild-type (WT) mice were compared to lens-wearing IL-17A/F single or double gene knock-out mice, or mice treated with UC7-13D5 monoclonal antibody to functionally deplete γδ T cells. Contralateral eyes served as no lens wear controls. Corneal Ly6G+ and γδ T cell responses were quantified as was expression of genes encoding pro-inflammatory cytokines IL-17A/F, IL-β, IL-18 and expression of IL-17A/F protein.

RESULTS

After 6 days lens wear, WT corneas showed Ly6G+ cell infiltration while remaining free of visible pathology. In contrast, lens-wearing corneas of IL-17AF (-/-), IL-17A (-/-) mice and γδ T cell-depleted mice showed little or no Ly6G+ cell infiltration. No Ly6G+ cell infiltration was detected in contralateral eye controls. Lens-wearing WT corneas also showed a significant increase in γδ T cells after 24 h that was maintained after 6 days of wear, and significantly increased cytokine gene expression after 6 days versus contralateral controls: IL-18 & IL-17A (∼3.9 fold) and IL-23 (∼6.5-fold). Increased IL-17A protein (∼4-fold) was detected after 6 days lens wear. γδ T cell-depletion abrogated these lens-induced changes in cytokine gene and protein expression.

CONCLUSION

Together, these data show that IL-17A and γδ T cells are required for Ly6G+ cell (neutrophil) infiltration of the cornea during contact lens-induced parainflammation.

Diurnal changes and topographical distribution of ocular surface epithelial dendritic cells in humans, and repeatability of density and morphology assessment

PURPOSE

Dendritic cells (DC) play a crucial role in ocular surface defence. DC can be visualised in vivo by confocal microscopy but have not yet been fully characterised in humans. This study investigated the diurnal variation, topographical distribution and repeatability of DC density and morphology measurements.

METHODS

In vivo confocal microscopy (IVCM) was conducted on 20 healthy participants (mean age 32.7 ± 6.4 years, 50% female) at baseline and repeated after 30 minutes, 2, 6 and 24 h. Images were captured at the corneal centre, inferior whorl, corneal periphery, limbus and bulbar conjunctiva. DC were counted manually, and their morphology was assessed for cell body size, presence of dendrites, and presence of long and thick dendrites. Mixed-model analysis, non-parametric analyses, Bland and Altman plots, coefficient of repeatability (CoR) and kappa were used.

RESULTS

There were no significant changes in DC density (p ≥ 0.74) or morphology (p > 0.07) at any location over the 24-h period. The highest DC density was observed at the corneal limbus followed by the peripheral cornea (p < 0.001), with the lowest density at the corneal centre, inferior whorl and bulbar conjunctiva. Most DC at the corneal periphery, limbus and bulbar conjunctiva had larger cell bodies compared with the corneal centre (p ≤ 0.01), and the presence of long dendrites was observed mostly at non-central locations. Day-to-day CoR for DC density ranged from ±28.1 cells/mm² at the corneal centre to ±56.4 cells/mm² at the limbus. Day-to-day agreement of DC morphology determined by kappa ranged from 0.5 to 0.95 for cell body size, 0.60 to 0.95 for presence of dendrites, and 0.55 to 0.80 for the presence of long dendrites at various locations.

CONCLUSIONS

No diurnal changes are apparent in corneal or conjunctival DC. Substantial topographical differences exist in DC density and morphology. IVCM provides good repeatability of DC density and acceptable agreement of DC morphology.

Proteomic profiling of human corneal stroma from long-term contact lens wearers reveals activation of inflammatory responses

PURPOSE

To investigate the association between proteomic changes and potential pathogenesis in the human cornea with respect to the duration of wearing soft contact lenses (SCLs).

METHODS

A total of 96 corneal stroma samples, obtained via small incision lenticule extraction (SMILE), were equally grouped according to the duration of wearing SCL: 0Y, did not wear SCL; 5Y, wore SCL for<5 years; 5-10Y, wore SCL for 5-10 years; O10Y, wore SCL for>10 years. Liquid chromatography-tandem mass spectrometry was used to identify and quantify protein profiles in the corneal stroma. Expression levels of CO1A1, CO4A1, NFKB1, and IL6RB were determined using western blot and immunohistochemistry analysis.

RESULTS

This study quantified a total of 5,668 proteins across samples and identified 2,379 differentially expressed proteins (DEPs) with significantly increased abundance in the three SCL-wearing groups compared with that in the non-SCL-wearing group. Compared with those in the 0Y group, the molecular functions of DEPs in the 5Y, 5-10Y, and O10Y groups were mainly related to translation regulator activity, antigen binding, peptidase inhibitor activity, participation in extracellular matrix (ECM) production, complement activation, and inflammatory responses. Pathway enrichment analysis of DEPs showed that the sphingolipid, phosphatidylinositol 3-kinase-protein kinase B, and hypoxia-inducible factor-1 signaling pathways were activated in the human corneal stroma after long-term SCL use.

CONCLUSIONS

Inflammation-related proteomic components in human corneal stroma increased after long-term use of SCL and may act as an essential factor in the molecular pathogenesis of corneal stroma damage.

Evaluation of Corneal Alterations After Short-Term Silicone Hydrogel Contact Lens Use by Confocal Microscopy

Objectives

To evaluate the corneal subbasal nerve morphology, corneal sensitivity, and anterior segment alterations in short-term silicone hydrogel contact lens (SiHCL) users by confocal microscopy.

Materials and Methods

The study included 25 right eyes of 25 male volunteers aged 25-30 years who had never used SiHCLs before. ocular surface disease index (OSDI), tear break-up time, Schirmer test, tear meniscus area, strip meniscometry tube, corneal sensitivity, and corneal subbasal nerve morphology were evaluated before and after 1 month of CL use.

Results

OSDI was 10.6±1.1 before CL use and 17.2±1.2 after 1 month of CL use (p<0.01). Schirmer test distance was 16.3±2.3 mm before and 14.3±1.9 mm after 1 month of CL use (p>0.05). Tear film break-up time was 7.1±0.4 s before and 6.2±0.3 s after CL use (p>0.05). The tear meniscus area was 0.026±0.002 mm2 before and 0.024±0.001 mm2 after 1 month of CL use (p>0.05). Strip meniscometry tube results were 5.4±0.9 mm before and 4.9±0.8 mm after 1 month of CL use (p>0.05). Corneal sensitivity values were 3.2±0.4 mm before and 2.95±0.3 mm after 1 month of CL use (p>0.05). Dendritic cell density evaluated by confocal microscopy was 14.84±3.1 cells/mm2 before and 32.57±4.2 cells/mm2 after 1 month of CL use (p<0.01). Subbasal nerve tortuosity was 0.92±0.2 before and 1.03±0.2 after 1 month of CL use (p>0.05). Subbasal nerve density was measured as 4726±310 pixels/frame before and 4570±272 pixels/frame after 1 month of CL use (p>0.05).

Conclusion

After a month of SiHCL use, no significant changes were observed in tear secretion, corneal sensitivity, tear meniscus volume, subbasal corneal nerve density, reflectivity, or tortuosity, while a significant increase was found in OSDI and dendritic cell density.

Density and distribution of dendritiform cells in the peripheral cornea of healthy subjects using in vivo confocal microscopy

PURPOSE

To establish dendritiform cell (DC) density and morphological parameters in the central and peripheral cornea in a large healthy cohort, using in vivo confocal microscopy (IVCM).

METHODS

A prospective, cross-sectional, observational study was conducted in 85 healthy volunteers (n = 85 eyes). IVCM images of corneal center and four peripheral zones were analyzed for DC density and morphology to compare means and assess correlations (p < 0.05 being statistically significant).

RESULTS

Central cornea had lower DC density (40.83 ± 5.14 cells/mm²; mean ± SEM) as compared to peripheral cornea (75.42 ± 2.67 cells/mm², p < 0.0001). Inferior and superior zones demonstrated higher DC density (105.01 ± 7.12 and 90.62 ± 4.62 cells/mm²) compared to the nasal and temporal zones (59.93 ± 3.42 and 51.77 ± 2.98 cells/mm², p < 0.0001). Similarly, lower DC size, field and number of dendrites were observed in the central as compared to the average peripheral cornea (p < 0.0001), with highest values in the inferior zone (p < 0.001 for all, except p < 0.05 for number of dendrites in superior zone). DC parameters did not correlate with age or gender. Inter-observer reliability was 0.987 for DC density and 0.771-0.922 for morphology.

CONCLUSION

In healthy individuals, the peripheral cornea demonstrates higher DC density and larger morphology compared to the center, with highest values in the inferior zone. We provide the largest normative cohort for sub-stratified DC density and morphology, which can be used in future clinical trials to compare differential changes in diseased states. Furthermore, as DC parameters in the peripheral zones are dissimilar, random sampling of peripheral cornea may be inaccurate.

Topical antibiotics reduce CD11c+ cell numbers in the healthy murine cornea and modulate their response to contact lens wear

Previously we reported contact lens-induced CD11c+ cell responses in healthy mouse corneas, a phenomenon that also occurs in humans. To test involvement of ocular-associated bacteria, the impact of topical antibiotics on corneal CD11c+ cell populations during 24 h of lens wear was examined. Corneas were treated with gentamicin and ofloxacin (0.3%) or gentamicin alone, some also treated prior to lens wear (24 h). Contralateral PBS-treated eyes served as controls. CD11c-YFP (Yellow Fluorescent Protein) mice allowed CD11c+ cell visualization. Viable bacteria, on the ocular surface or contact lens, were labeled using FISH (16S rRNA-targeted probe) or click-chemistry (alkDala). Antibiotic treatment reduced baseline CD11c+ cell numbers without lens wear and suppressed CD11c+ cell responses to lens wear if corneas were both pretreated and treated during wear. Few bacteria colonized corneas or lenses under any circumstances. Conjunctival commensals were significantly reduced by antibiotics with or without lens wear, but minimally impacted by lens wear alone. Deliberate inoculation with conjunctival commensals triggered CD11c+ cell responses irrespective of antibiotic pretreatment. These results suggest that while lens wear does not necessarily increase quantifiable numbers of conjunctival commensals, those neutralized by antibiotics play a role in lens-associated CD11c+ cell responses and maintaining baseline CD11c+ cell populations.

Diurnal Variation of Corneal Dendritic Cell Density

Purpose: To measure variation in corneal dendritic cell density, and percentage of mature to total dendritic cells, in healthy individuals during the sleep/wake cycle.Methods: Using in vivo confocal microscopy, images of the subbasal nerve plexus were captured from 19 healthy, noncontact lens wearing participants. The central cornea and inferior whorl were imaged three times (midday, before sleep, upon awakening). Dendritic cell counts from the images were categorized according to perceived maturity (immature vs mature). Dendritic cell density and percentage of mature to total cells were compared between time points.Result: The median and interquartile range (IQR) of total dendritic cell density in the central cornea was 32.0 (7.0-131.3) cells/mm² at midday, 37.1 (8.2-103.9) cells/mm² before sleep, and 19.5 (7.0-83.2) cells/mm² on awakening. Corresponding values for immature cells were 28.1 (5.8-112.5) cells/mm², 22.3 (7.4-84.0) cells/mm² and 18.0 (2.9-64.8) cells/mm², and for mature cells, 3.1 (0.0-6.6) cells/mm², 2.0 (0.8-16.8) cells/mm², and 1.6 (0.2-8.2) cells/mm². At the inferior whorl, total dendritic cell density was 38.5 (18.4-84.5) cells/mm², 34.4 (9.4-82.3) cell/mm², and 32.3 (15.2-96.1) cells/mm². Immature cell density was 32.8 (18.4-80.9) cells/mm², 34.4 (8.6-81.0) cells/mm², and 32.3 (12.6-78.5) cells/mm². Mature cell density was 1.6 (0.0-6.3) cells/mm², 1.6 (0.0-3.1) cells/mm², and 1.8 (0.0-6.3) cells/mm². There was no significant difference between time points for total cell density (p > 0.05), but the percentage of mature cells upon awakening was significantly greater, compared to midday, at the central cornea (p = 0.02).Conclusion: In healthy individuals, overall corneal dendritic cell density is reasonably constant during the sleep/wake cycle, but the relative number of mature cells tends to increase overnight.

Evaluation of Ocular Surface Characteristics in Dry Eye Disease With and Without Soft Contact Lens Wear: A Comparative Study

OBJECTIVES

To investigate ocular surface alterations and in vivo confocal microscopic characteristics of the cornea in dry eye disease (DED) with contact lens wear (CLW).

METHODS

Sixty participants were divided into three groups: DED with CLW (n=20), DED without CLW (n=20), and normal control (n=20). Ocular surface parameters were evaluated. Basal tears and in vivo confocal microscopy images of the cornea were collected. Multiplex bead analysis was used to assess interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, nerve growth factor (NGF), and substance P (SP) in tears. Nerve morphology and dendritic cell density in corneal subbasal nerve images were calculated.

RESULTS

The DED with CLW group showed significantly higher ocular surface staining scores (P=0.022) and higher levels of IL-1β, NGF, and SP in tears (P=0.014, P=0.004 and P=0.025) than the DED without CLW group. Corneal dendritic cell density in the DED with CLW group was significantly higher than that in the normal controls (P=0.001) and DED without CLW group (P=0.043). Tear cytokine levels of IL-1β, NGF, and SP were correlated with ocular surface parameters in the DED with CLW group. Moreover, the years of CLW were positively correlated with corneal dendritic cell density (r=0.527, P=0.017) and negatively correlated with corneal nerve density (r=-0.511, P=0.021).

CONCLUSIONS

Patients with DED with CLW showed greater epithelial damage, elevated inflammatory cytokines and neuromediators in tears, and higher corneal dendritic cell density than patients with DED without CLW. The immune and nervous systems may be involved in contact lens-related DED.

Corneal Dendritic Cell Dynamics Are Associated with Clinical Factors in Type 1 Diabetes

Time-lapsed in vivo corneal confocal microscopy (IVCCM) has shown that corneal dendritic cells (DCs) migrate at approximately 1 µm/min in healthy humans. We have undertaken IVCCM of the whorl region to compare the density of rounded DCs, and DCs with (wDCs) and without (woDCs) dendrites and dynamics; trajectory (length travelled/time), displacement (distance from origin to endpoint/time) speeds and persistence ratio (displacement/trajectory) of woDCs in subjects with type 1 diabetes (T1D) (n = 20) and healthy controls (n = 10). Only the wDC density was higher (p = 0.02) in subjects with T1D compared to controls. There was no significant difference in cell dynamics between subjects with T1D and controls. woDC density correlated directly with HDL cholesterol (r = 0.59, p = 0.007) and inversely with triglycerides (r = −0.61, p = 0.005), whilst round-shaped cell density correlated inversely with HDL cholesterol (r = −0.54, p = 0.007). Displacement, trajectory, and persistency correlated significantly with eGFR (mL/min) (r = 0.74, p < 0.001; r = 0.48, p = 0.031; r = 0.58, p = 0.008, respectively). We show an increase in wDC density but no change in any other DC sub-type or alteration in cell dynamics in T1D. However, there were associations between DC density and lipid parameters and between DC dynamics and renal function. IVCCM provides evidence of a link between immune cell dynamics with lipid levels and renal function.

Dynamic Changes of Ocular Surface in First-Time Contact Lens Wearers and the Effective Factors of Contact Lens Discomfort

Purpose

The purpose of the study is to investigate the dynamic changes in ocular surface indicators in first-time contact lens (CL) wearers and identify the most influential factors in CL discomfort (CLD).

Methods

A total of 26 healthy non-CL wearers (26 eyes) were recruited and fitted monthly with disposable hydrogel CLs. Each participant underwent a full ocular surface evaluation, which include Efron grading, tear film breakup time, Schirmer's I test, corneal dendritic cell (DCs) imaging by in vivo confocal microscopy (IVCM), and conjunctival microvasculature evaluation by functional slit-lamp biomicroscopy. CLD was assessed using the Ocular Surface Disease Index questionnaire at baseline, 1 week, 1, 3, and 6 months after wearing it and another 6 months after discontinuing it.

Results

Clinical signs and CLD were significantly increased in the first week (p < 0.05). The microvascular response and DC activation peaked at the 1-month interval (p < 0.05). During CL wear, CLD is positively correlated with corneal staining (B = 0.238, p = 0.002), papillary conjunctivitis (B = 0.245, p < 0.001), and microvascular blood flow velocity (B = 0.353, p < 0.001). After discontinuation, only DC activation remained elevated at 6 months, whereas the other signs recovered.

Conclusions

The first week of CL wear was the main period for the appearance of ocular surface clinical signs, and the first month was the main period for the activation of subclinical inflammation. Corneal staining and conjunctival microvascular response are the main factors affecting CLD. Even if the clinical signs recover after discontinuing wear, subclinical inflammation may persist.

Corneal inflammatory cell infiltration predicts disease activity in chronic inflammatory demyelinating polyneuropathy

The assessment of disease activity is fundamental in the management of chronic inflammatory demyelinating polyneuropathy (CIDP). Previous studies with small patient numbers found an increase of corneal immune cell infiltrates as a potential marker of inflammation in patients with CIDP. However, its clinical relevance remained unclear. The present study aimed to determine whether the amount of corneal inflammatory cells (CIC) measured by corneal confocal microscopy (CCM) detects disease activity in CIDP. CIC were measured in 142 CCM-investigations of 97 CIDP-patients. Data on clinical disease activity, disability (INCAT-ODSS) and need for therapy escalation at the timepoint of CCM, 3 and 6 months later were analyzed depending CIC-count. Pathological spontaneous activity during electromyography was examined as another possible biomarker for disease activity in comparison to CIC-count. An increased CIC-count at baseline was found in patients with clinical disease activity and disability progression in the following 3-6 months. An increase to more than 25 CIC/mm² had a sensitivity of 0.73 and a specificity of 0.71 to detect clinical disease activity and a sensitivity of 0.77 and a specificity of 0.64 to detect disability progression (increasing INCAT-ODSS) in the following 6 months. An increase to more than 50 CIC/mm² had a sensitivity of about 0.51 and a specificity of 0.91 to detect clinical disease activity and a sensitivity of 0.53 and a specificity of 0.80 to detect disability progression. CIC count is a non-invasive biomarker for the detection of disease activity in the following 6 months in CIDP.

Effect of material and care system combination on subclinical inflammation of the ocular surface in soft contact lens wear

PURPOSE

To investigate the ocular subclinical inflammatory response in two soft contact lens materials when used in combination with two different care systems ('solutions').

METHODS

Fifteen established soft contact lens wearers wore each of two lenses: Acuvue® 2 (CH) and Acuvue® Oasys® (SiH) or no lenses in random sequence for one week. Two care systems were used: a peroxide system: Oxysept 1 Step® (P) for the right lens and Opti-Free® Replenish® (MPS) for the left lens. After one week of lens/no lens wear, in vivo confocal microscopy (IVCM) of corneal and conjunctival regions was carried out. Density of presumed dendritic cells (DC) and 'white spots' (WS) were quantified. Impression cytology of the bulbar and upper eyelid margin conjunctivae was carried out and samples were analysed for CD45+, CD3+ and CD11c+ cells.

RESULTS

The SiH + MPS combination showed a greater inflammatory response compared to SiH + P in seven out of 12 parameters investigated (p < 0.05). The remaining five were not statistically different between the two solutions. The converse was found for the CH lens, with four of the 12 parameters showing a greater response with the P solution compared to the MPS (p < 0.05).

CONCLUSION

This study suggests that the SiH lens investigated demonstrated an upregulated response when used with a MPS compared to a P solution whereas the converse is true for the CH lens which showed a reduced response when used with a MPS compared to a P solution. This finding aids in the understanding of the biological underpinnings of manifest corneal inflammatory events during contact lens wear.

Changes in Corneal Dendritic Cell and Sub-basal Nerve in Long-Term Contact Lens Wearers With Dry Eye

OBJECTIVES

To evaluate the changes of corneal sub-basal nerve (SBN) and dendritic cell (DC) in contact lens (CL) wearers with mild dry eye and their potential relationship.

METHODS

Twenty mild dry eye volunteers who had never worn CLs were recruited for long-term CL wearing. Each subject underwent ocular surface evaluations at baseline and at 1, 4, 12, and 24 weeks, including Ocular Surface Disease Index (OSDI) questionnaire, tear film break-up time (TBUT), and Schirmer I test. In vivo confocal microscopy was used to examine the density, area, number of dendrites, total dendritic length of DC, and SBN densities in central and peripheral corneas. Only right eyes were included.

RESULTS

The DCs were activated and peaked at week 4 after wearing CLs. The peripheral DC density increased beginning the first week, whereas the central ones increased by week 4. After 4 weeks, both began to decrease, but still higher than baseline at week 24. The central and peripheral SBN densities decreased. However, the peripheral SBN tended to increase beginning at week 12. In early period, SBN was negatively correlated with DC parameters. After 4 weeks, the correlation changed to be positive. The OSDI increased, whereas the Schirmer I test and TBUT showed no significant change.

CONCLUSIONS

After wearing CLs, corneal DC were activated and increased, indicating ocular surface inflammation and decreased after week 4. In the early period, increases in DC may lead to decreases in SBN. Upon decrease of DC, the SBN may regenerate.

Ocular Surface Changes Associated with Ophthalmic Surgery

Dry eye disease causes ocular discomfort and visual disturbances. Older adults are at a higher risk of developing dry eye disease as well as needing for ophthalmic surgery. Anterior segment surgery may induce or worsen existing dry eye symptoms usually for a short-term period. Despite good visual outcomes, ocular surface dysfunction can significantly affect quality of life and, therefore, lower a patient’s satisfaction with ophthalmic surgery. Preoperative dry eye disease, factors during surgery and postoperative treatment may all contribute to ocular surface dysfunction and its severity. We reviewed relevant articles from 2010 through to 2021 using keywords “cataract surgery”, ”phacoemulsification”, ”refractive surgery”, ”trabeculectomy”, ”vitrectomy” in combination with ”ocular surface dysfunction”, “dry eye disease”, and analyzed studies on dry eye disease pathophysiology and the impact of anterior segment surgery on the ocular surface.

In vivo Confocal Microscopic Evaluation of Corneal Dendritic Cell Density and Subbasal Nerve Parameters in Dry Eye Patients: A Systematic Review and Meta-analysis

Purpose: To conduct a systematic review and meta-analysis of the available research on evaluating changes in corneal dendritic cell density (CDCD) and the main subbasal nerve parameters (SNPs) on the ocular surface and assessing the diagnostic performance of in vivo confocal microscopy in patients with dry eye disease. Methods: A computerized systematic review of literature published in PUBMED, EMBASE, Web of Science, Scopus, and the Cochrane Central Register of Controlled Trials until May 8, 2020 was performed. All statistical analyses were conducted in RevMan V.5.3 software. The weighted mean differences (WMDs) and standardized mean differences (SMDs) with 95% confidence intervals (CI) between dry eye patients and healthy subjects were presented as results. Results: A total of 11 studies with 755 participants were recruited, and 931 eyes were included in this meta-analysis. However, not all studies reported both CDCD and SNPs. CDCD in the central cornea was higher (WMD = 51.06, 95% CI = 39.42-62.71), while corneal nerve fiber density (CNFD) and corneal nerve fiber length (CNFL) were lower (WMD = -7.96, 95% CI = -12.12 to -3.81; SMD = -2.30, 95%CI = -3.26 to -1.35) in dry eye patients in comparison with the corresponding values in healthy controls (all p < 0.00001). Conclusion: Taken together, while CNFD and CNFL were lower in dry eye patients, central CDCD showed a significant increase in these patients in comparison with the corresponding values in healthy controls.

In Vivo Confocal Microscopy in Blepharitis Patients with Ocular Demodex Infestation

PURPOSE

To compare corneal in-vivo confocal microscopy (IVCM) findings in patients with seborrheic blepharitis with healthy controls and to evaluate the correlation with the Demodex load.

METHODS

Sixty-two Demodex positive seborrheic blepharitis patients and 24 controls were included. Four eyelashes from each eye were examined. The median value of Demodex count (5 mites/eye) was assigned as the cutoff value to create low and high Demodex infestation subgroups. Corneal nerve parameters (fiber length;CNFL, fiber density;CNFD, branch length;CNBL, branch density;CNBD) and dendritic cell density (DCD) were analyzed by IVCM for all participants.

RESULTS

The mean DCD of eyes in low (37.62 ± 25.18 cells/mm²) and high (76.00 ± 44.00 cells/mm²) Demodex load groups were significantly higher than those in the control group (14.25 ± 2.68 cells/mm²) (p < .001). CNFL, CNFD, CNBL and CNBD were significantly lower in low and high Demodex groups compared to controls (p < .001).

CONCLUSIONS

Demodex positive seborrheic blepharitis patients showed significantly reduced density of corneal nerves and elevated DCD levels.

CLEAR - Effect of contact lens materials and designs on the anatomy and physiology of the eye

This paper outlines changes to the ocular surface caused by contact lenses and their degree of clinical significance. Substantial research and development to improve oxygen permeability of rigid and soft contact lenses has meant that in many countries the issues caused by hypoxia to the ocular surface have largely been negated. The ability of contact lenses to change the axial growth characteristics of the globe is being utilised to help reduce the myopia pandemic and several studies and meta-analyses have shown that wearing orthokeratology lenses or soft multifocal contact lenses can reduce axial length growth (and hence myopia). However, effects on blinking, ptosis, the function of Meibomian glands, fluorescein and lissamine green staining of the conjunctiva and cornea, production of lid-parallel conjunctival folds and lid wiper epitheliopathy have received less research attention. Contact lens wear produces a subclinical inflammatory response manifested by increases in the number of dendritiform cells in the conjunctiva, cornea and limbus. Papillary conjunctivitis is also a complication of all types of contact lenses. Changes to wear schedule (daily disposable from overnight wear) or lens materials (hydrogel from SiHy) can reduce papillary conjunctivitis, but the effect of such changes on dendritic cell migration needs further study. These changes may be associated with decreased comfort but confirmatory studies are needed. Contact lenses can affect the sensitivity of the ocular surface to mechanical stimulation, but whether these changes affect comfort requires further investigation. In conclusion, there have been changes to lens materials, design and wear schedules over the past 20+ years that have improved their safety and seen the development of lenses that can reduce the myopia development. However, several changes to the ocular surface still occur and warrant further research effort in order to optimise the lens wearing experience.

A Review of Imaging Biomarkers of the Ocular Surface

A biomarker is a "characteristic that is measured as an indicator of normal biological processes, pathogenic processes, or responses to an exposure or intervention, including therapeutic interventions." Recently, calls for biomarkers for ocular surface diseases have increased, and advancements in imaging technologies have aided in allowing imaging biomarkers to serve as a potential solution for this need. This review focuses on the state of imaging biomarkers for ocular surface diseases, specifically non-invasive tear break-up time (NIBUT), tear meniscus measurement and corneal epithelial thickness with anterior segment optical coherence tomography (OCT), meibomian gland morphology with infrared meibography and in vivo confocal microscopy (IVCM), ocular redness with grading scales, and cellular corneal immune cells and nerve assessment by IVCM. Extensive literature review was performed for analytical and clinical validation that currently exists for potential imaging biomarkers. Our summary suggests that the reported analytical and clinical validation state for potential imaging biomarkers is broad, with some having good to excellent intra- and intergrader agreement to date. Examples of these include NIBUT for dry eye disease, ocular redness grading scales, and detection of corneal immune cells by IVCM for grading and monitoring inflammation. Further examples are nerve assessment by IVCM for monitoring severity of diabetes mellitus and neurotrophic keratitis, and corneal epithelial thickness assessment with anterior segment OCT for the diagnosis of early keratoconus. However, additional analytical validation for these biomarkers is required before clinical application as a biomarker.

Advances in Screening, Early Diagnosis and Accurate Staging of Diabetic Neuropathy

The incidence of both type 1 and type 2 diabetes is increasing worldwide. Diabetic peripheral neuropathy (DPN) is among the most distressing and costly of all the chronic complications of diabetes and is a cause of significant disability and poor quality of life. This incurs a significant burden on health care costs and society, especially as these young people enter their peak working and earning capacity at the time when diabetes-related complications most often first occur. DPN is often asymptomatic during the early stages; however, once symptoms and overt deficits have developed, it cannot be reversed. Therefore, early diagnosis and timely intervention are essential to prevent the development and progression of diabetic neuropathy. The diagnosis of DPN, the determination of the global prevalence, and incidence rates of DPN remain challenging. The opinions vary about the effectiveness of the expansion of screenings to enable early diagnosis and treatment initiation before disease onset and progression. Although research has evolved over the years, DPN still represents an enormous burden for clinicians and health systems worldwide due to its difficult diagnosis, high costs related to treatment, and the multidisciplinary approach required for effective management. Therefore, there is an unmet need for reliable surrogate biomarkers to monitor the onset and progression of early neuropathic changes in DPN and facilitate drug discovery. In this review paper, the aim was to assess the currently available tests for DPN's sensitivity and performance.

In vivo immune cell dynamics in the human cornea

In vivo confocal microscopy (IVCM) allows the evaluation of the living human cornea at the cellular level. The non-invasive nature of this technique longitudinal, repeated examinations of the same tissue over time. Image analysis of two-dimensional time-lapse sequences of presumed immune cells with and without visible dendrites at the corneal sub-basal nerve plexus in the eyes of healthy individuals was performed. We demonstrated evidence that cells without visible dendrites are highly dynamic and move rapidly in the axial directions. A number of dynamic cells were observed and measured from three eyes of different individuals. The total average displacement and trajectory speeds of three cells without visible dendrites (N = 9) was calculated to be 1.12 ± 0.21 and 1.35 ± 0.17 μm per minute, respectively. One cell with visible dendrites per cornea was also analysed. Tracking dendritic cell dynamics in vivo has the potential to significantly advance the understanding of the human immune adaptive and innate systems. The ability to observe and quantify migration rates of immune cells in vivo is likely to reveal previously unknown insights into corneal and general pathophysiology and may serve as an effective indicator of cellular responses to intervention therapies.

Association between conjunctival goblet cells and corneal resident dendritic cell density changes in new contact lens wearers

BACKGROUND

To explore the interlink between conjunctival goblet and corneal dendritic cell density after six months of lens wear and to predict dendritic cell migration to the central cornea based on goblet cell loss in the conjunctiva as a response to contact lens wear.

METHODS

Sixty-nine subjects who had never previously worn contact lenses were observed for six months; 46 were fitted with contact lenses and 21 served as a control group. Corneal confocal microscopy was used to quantify goblet and dendritic cell density before and after six months of daily lens wear. Symptomatic and asymptomatic groups were identified in the lens-wearing group using a combination of signs and symptoms present. Pearson's correlation was used to determine associations between the total change of cell densities after six months of lens wear.

RESULTS

At baseline, there was no association between conjunctival goblet and corneal dendritic cell density (p > 0.05). After six months, there was an inverse association between the absolute change of conjunctival goblet and corneal dendritic cell density (ρ = -0.34, p = 0.03) in all participants (n = 69). Dendritic cell density in the central cornea was increased by 1.5 cells/mm² for every decrease of 1 goblet cell/mm² in the conjunctiva.

CONCLUSIONS

After six months of wear, contact lens-induced goblet cell loss can partially predict resident corneal dendritic cell migration to the central cornea (observed as an increase in dendritic cell density). The associations between total cell density change after six months was established in wearers regardless of lens symptomatology, suggesting that cell density changes as a physiological adaptation to regulate the effect of contact lens wear on the ocular surface.

The Role of Soft Contact Lens Wear on Meibomian Gland Morphology and Function

PURPOSE

To evaluate the impact of soft contact lens (CL) wear on the morphology and function of the meibomian glands (MG).

METHODS

One hundred seventy-three eyes of 87 soft CL wearers and 103 eyes of 55 age-matched healthy volunteers were included into this study. The patients were divided into 3 groups according to the total duration of lens wear: less than 3 years, 3 to 7 years, and more than 7 years. Ocular Surface Disease Index (OSDI) scores, slitlamp biomicroscopy findings, fluorescein staining of the ocular surface, tear film break-up time (BUT), Schirmer I test, and meibography findings were recorded in all patient eyes and were compared with controls.

RESULTS

The mean meiboscores of the upper and lower eyelids were significantly higher in CL wearers compared with controls (P<0.05). The mean BUT and the mean MG expressibility were significantly lower, whereas the mean OSDI score, corneal staining scores, percentage of partial/complete gland loss, and percentage of thickened and curled MG in upper/lower lids were statistically significantly higher in CL wearers (P<0.05). Meiboscores were significantly higher in patients with a total lens wear duration of more than 3 years compared to those with less than 3 years of lens wear for both upper/lower lids (P<0.05). The earliest morphological change in the MG of CL wearers was MG thickening, and this parameter was the only meibography finding that had the highest diagnostic ability for MG dysfunction.

CONCLUSION

Soft CL wear causes significant morphological and functional changes in MG with thickening of MG presenting an early diagnostic finding of MG dysfunction on meibography.

The Innate Immune Cell Profile of the Cornea Predicts the Onset of Ocular Surface Inflammatory Disorders

Ocular surface inflammatory disorder (OSID) is a spectrum of disorders that have features of several etiologies whilst displaying similar phenotypic signs of ocular inflammation. They are complicated disorders with underlying mechanisms related to several autoimmune disorders, such as rheumatoid arthritis (RA), Sjögren’s syndrome, and systemic lupus erythematosus (SLE). Current literature shows the involvement of both innate and adaptive arms of the immune system in ocular surface inflammation. The ocular surface contains distinct components of the immune system in the conjunctiva and the cornea. The normal conjunctiva epithelium and sub-epithelial stroma contains resident immune cells, such as T cells, B cells (adaptive), dendritic cells, and macrophages (innate). The relative sterile environment of the cornea is achieved by the tolerogenic properties of dendritic cells in the conjunctiva, the presence of regulatory lymphocytes, and the existence of soluble immunosuppressive factors, such as the transforming growth factor (TGF)-β and macrophage migration inhibitory factors. With the presence of both innate and adaptive immune system components, it is intriguing to investigate the most important leukocyte population in the ocular surface, which is involved in immune surveillance. Our meta-analysis investigates into this with a focus on both infectious (contact lens wear, corneal graft rejection, Cytomegalovirus, keratitis, scleritis, ocular surgery) and non-infectious (dry eye disease, glaucoma, graft-vs-host disease, Sjögren’s syndrome) situations. We have found the predominance of dendritic cells in ocular surface diseases, along with the Th-related cytokines. Our goal is to improve the knowledge of immune cells in OSID and to open new dimensions in the field. The purpose of this study is not to limit ourselves in the ocular system, but to investigate the importance of dendritic cells in the disorders of other mucosal organs (e.g., lungs, gut, uterus). Holistically, we want to investigate if this is a common trend in the initiation of any disease related to the mucosal organs and find a unified therapeutic approach. In addition, we want to show the power of computational approaches to foster a collaboration between computational and biological science.

Not All Dry Eye in Contact Lens Wear Is Contact Lens-Induced

OBJECTIVES

To compare subjective and clinical outcomes in three study groups: (1) asymptomatic contact lens (CL) wearers (ASYM); (2) symptomatic CL wearers who become asymptomatic on lens removal; and (3) symptomatic CL wearers who do not resolve on lens removal.

METHODS

Ninety-two subjects completed the Berkeley Dry Eye Flow Chart with and without lenses, ocular surface examinations, and a battery of questionnaires.

RESULTS

Thirty-seven subjects (40%) were ASYM, 30 (33%) had contact lens-induced dry eye (CLIDE), and 25 (27%) had underlying physiological DE. Visual Analog Scale ratings, OSDI score, and SPEED score were significantly better for the ASYM group (P<0.001) but did not distinguish CLIDE from DE. The DE group was significantly worse than CLIDE and ASYM, which were similar, in precorneal noninvasive tear breakup time (8.2 sec DE vs. 12.3 sec CLIDE and 14.3 sec ASYM; P=0.002), anterior displacement of the Line of Marx (P=0.017), and superior conjunctival staining (P=0.001).

CONCLUSIONS

Many CL wearers presenting with dryness symptoms have an underlying DE condition and will not respond to treatments aimed at changing lenses or solutions. Contradictory results from research studies of DE in CL wearers could be due in part to a failure to distinguish subjects with symptoms due specifically to CL wear from those whose symptoms have underlying causes unrelated to CL wear.

Corneal epithelial dendritic cell density in the healthy human cornea: A meta-analysis of in-vivo confocal microscopy data

PURPOSE

Numerous studies have reported a wide range of corneal epithelial dendritic cells (CEDC) density using in-vivo confocal microscopy in healthy participants. It is necessary to establish normal CEDC values for healthy corneas to enable differentiation from pathological corneas. This meta-analysis aimed to establish CEDC density and distribution and examine their relationship with age and sex.

METHODS

A systematic review of the literature of studies using the Heidelberg Retinal Tomograph with Rostock Corneal Module and reporting CEDC density in healthy subjects up to December 2018 was conducted via Medline, Google Scholar, Scopus, PubMed, Embase and Cochrane library. A random effect modeling approach was used to obtain the results of meta-analysis and meta-regression was conducted to estimate the effect of age and sex.

RESULTS

38 studies reported central and 9 reported peripheral inferior CEDC density of 1203 participants (mean age 46.0 ± 12.2, range 18-81 years). CEDC density in the central and peripheral inferior cornea was 26.4 ± 13.6 cells/mm² (95% CI:22.5-26.8) and 74.9 ± 22.7 cells/mm² (95%CI:59.8-90.0), respectively. No effect of age was found on central CEDC density (p = 0.63); whereas peripheral CEDC density decreased with increasing age (p = 0.02). CEDC density was not influenced by sex at either location (p > 0.48).

CONCLUSION

This study established that the density at the peripheral inferior cornea is three-fold higher than at the central cornea. Peripheral but not central CEDC density decreased with increasing age. There are limited studies in youth (<18 years), precluding a more detailed analysis. Sex does not appear to be a significant factor in CEDC density.

A review of functional slit lamp biomicroscopy

Functional slit lamp biomicroscopy (FSLB) is a novel device which consists of a traditional slit-lamp and a digital camera. It can quantitatively assess vessel diameter, blood flow velocity, and blood flow rate and can create noninvasive microvascular perfusion maps (nMPMs). At present, FSLB is mainly used in contact lens (CL) and dry eye disease (DED) studies to advance our understanding of ocular surface microcirculation. FSLB-derived blood flow and vessel density measures are significantly altered in CL wearers and DED patients compared to normal people. These subtle changes in the ocular surface microcirculation may contribute to the monitoring of potential diseases of the body and provide a new way to diagnose dry eye disease. Therefore, this may also indicate that FSLB can be more widely applied in the study of other diseases to reveal the relationship between changes in ocular surface microcirculation and systemic diseases. The purpose of this paper is to summarize the functions of FSLB and the related studies especially in CL and DED.

Modulating Contact Lens Discomfort With Anti-Inflammatory Approaches: A Randomized Controlled Trial

Purpose

To assess the efficacy of anti-inflammatory approaches, comprising a topical corticosteroid and omega-3 supplements, for modulating the inflammatory overlay associated with contact lens discomfort (CLD).

Methods

This randomized controlled trial involved 72 adults with CLD, randomized (1:1:1:1) to one of the following: placebo (oral olive oil), oral fish oil (900 mg/d eicosapentaenoic acid [EPA] + 600 mg/d docosohexaenoic acid [DHA]), oral combined fish+flaxseed oils (900 mg/d EPA + 600 mg/d DHA + 900 mg/d alpha-linolenic acid), or omega-3 eye-drops (0.025% EPA + 0.0025% DHA four times per day [qid]) for 12 weeks, with visits at baseline, weeks 4 and 12. At week 12, participants who received placebo were assigned a low-potency corticosteroid (fluorometholone [FML] 0.1%, drops, three times per day [tid]) for 2 weeks (week 14).

Results

Sixty-five participants completed the primary endpoint. At week 12, contact lens dry-eye questionnaire (CLDEQ-8) score was reduced from baseline with oral fish oil (-7.3 ± 0.8 units, n = 17, P < 0.05), compared with placebo (-3.5 ± 0.9 units, n = 16). FML produced significant reductions in tear IL-17A (-71.1 ± 14.3%, n = 12) and IL-6 (-47.6 ± 17.5%, n = 12, P < 0.05) relative to its baseline (week 12). At week 12, tear IL-17A levels were reduced from baseline in the oral fish oil (-63.2 ± 12.8%, n = 12, P < 0.05) and topical omega-3 (-76.2 ± 10.8%, n = 10, P < 0.05) groups, compared with placebo (-3.8 ± 12.7%, n = 12). Tear IL-6 was reduced with all omega-3 interventions, relative to placebo (P < 0.05) at week 12.

Conclusions

CLD was attenuated by oral long-chain omega-3 supplementation for 12 weeks. Acute (2 week) topical corticosteroids and longer-term (12 week) omega-3 supplementation reduced tear levels of the proinflammatory cytokines IL-17A and IL-6, demonstrating parallels in modulating ocular inflammation with these approaches.

A novel murine model for contact lens wear reveals clandestine IL-1R dependent corneal parainflammation and susceptibility to microbial keratitis upon inoculation with Pseudomonas aeruginosa

PURPOSE

Contact lens wear carries a risk of complications, including corneal infection. Solving these complications has been hindered by limitations of existing animal models. Here, we report development of a new murine model of contact lens wear.

METHODS

C57BL/6 mice were fitted with custom-made silicone-hydrogel contact lenses with or without prior inoculation with Pseudomonas aeruginosa (PAO1-GFP). Contralateral eyes served as controls. Corneas were monitored for pathology, and examined ex vivo using high-magnification, time-lapse imaging. Fluorescent reporter mice allowed visualization of host cell membranes and immune cells. Lens-colonizing bacteria were detected by viable counts and FISH. Direct-colony PCR was used for bacterial identification.

RESULTS

Without deliberate inoculation, lens-wearing corneas remained free of visible pathology, and retained a clarity similar to non-lens wearing controls. CD11c-YFP reporter mice revealed altered numbers, and distribution, of CD11c-positive cells in lens-wearing corneas after 24 h. Worn lenses showed bacterial colonization, primarily by known conjunctival or skin commensals. Corneal epithelial cells showed vacuolization during lens wear, and after 5 days, cells with phagocyte morphology appeared in the stroma that actively migrated over resident keratocytes that showed altered morphology. Immunofluorescence confirmed stromal Ly6G-positive cells after 5 days of lens wear, but not in MyD88 or IL-1R gene-knockout mice. P. aeruginosa-contaminated lenses caused infectious pathology in most mice from 1 to 13 days.

CONCLUSIONS

This murine model of contact lens wear appears to faithfully mimic events occurring during human lens wear, and could be valuable for experiments, not possible in humans, that help solve the pathogenesis of lens-related complications.

Tear film inflammatory cytokine upregulation in contact lens discomfort

PURPOSE

To investigate the ocular inflammatory response, using clinical and immunological techniques, in people experiencing contact lens (CL) discomfort.

METHODS

This study involved 38 adults who were full-time, silicone-hydrogel CL wearers. Participants were categorized into groups based upon a validated CL dry-eye questionnaire (CLDEQ-8) (n = 17 'asymptomatic', CLDEQ-8 score <9; n = 21 'symptomatic', CLDEQ-8 score ≥13). Examinations were performed at two visits (one with, and one without, CL wear), separated by one-week. Testing included: tear osmolarity, ocular redness, tear stability, ocular surface staining, meibography, tear production and tear collection. Tear osmolarity was taken from the inferior-lateral and superior-lateral menisci. The 'Inferior-Superior Osmotic Difference', I-SOD, was the absolute osmolarity difference between these menisci. Concentrations of seven cytokines (IL-2, IL-4, IL-6, IL-10, IL-17A, IFN-gamma, TNF-alpha) were assayed from basal tears using multiplex cytometric bead array.

RESULTS

At baseline, there was no significant difference in key clinical signs between asymptomatic and symptomatic CL wearers (p > 0.05). The I-SOD was greater in symptomatic than asymptomatic CL wearers (23.1 ± 2.6 versus 11.3 ± 1.4 mOsmol/L, p = 0.001). People experiencing CL discomfort had higher tear IL-17A (122.6 ± 23.7 versus 44.0 ± 10.0 pg/mL, p = 0.02) and reduced tear stability (6.3 ± 1.1 versus 10.4 ± 1.6 s, p = 0.03) after several hours of CL wear. Tear IL-17A levels correlated with both the I-SOD (r = 0.43, p = 0.01) and CLDEQ-8 score (r = 0.40, p = 0.01).

CONCLUSIONS

CL discomfort occurs in individuals having no clinical dry eye signs, and is associated with higher tear levels of the pro-inflammatory cytokine IL-17A. These findings support an association between the discomfort response and low-grade, ocular surface inflammation.

Evaluated Conjunctival Blood Flow Velocity in Daily Contact Lens Wearers

OBJECTIVE

This study examined conjunctival microvasculature development in long-term habitual contact lens (HCL) wearers after a night of sleep.

METHODS

Twenty HCL wearers (15 women and 5 men, aged 28.6±6.9 years, mean age±standard deviation) who had worn contact lenses on a daily basis for at least 3 years and 40 noncontact lens (NCL) wearers (23 women and 17 men, aged 36.5±6.6 years, mean age±standard deviation) participated in the study. A functional slitlamp biomicroscopy imaging system was used to image the temporal bulbar conjunctiva. Imaging was performed in the morning while the contact lens wearers were not wearing their lenses after a night of sleep. The conjunctival vessel diameters, blood flow velocities, and flow rates were measured. In addition, fractal analyses were performed to obtain the vessel network density (Dbox) and complexity (D0).

RESULTS

The average blood flow velocity in HCL wearers after a night of sleep was 0.59±0.19 mm/s, which was significantly higher than that in NCL wearers (0.48±0.17 mm/s, P<0.05). The microvessel network density and complexity levels (Dbox=1.64±0.05 and D0=1.71±0.05, respectively) in the HCL wearers were significantly higher than those in NCL wearers (Dbox=1.61±0.05 and D0=1.69±0.04, both P<0.05). The blood flow velocity was positively correlated with the duration of contact lens wear (r=0.46, P<0.05) and with the daily number of lens-wearing hours (r=0.49, P<0.05) in HCL wearers.

CONCLUSIONS

This study identified microvascular alterations in the conjunctiva in response to daily contact lens wear after a night of sleep in long-term daily contact lens wearers. The unrecovered changes may indicate that para-inflammation occurs on ocular surfaces because of contact lens wear and that overnight sleeping with no lenses may not sufficiently restore the ocular surface to an intact state.

Tear film evaluation and management in soft contact lens wear: a systematic approach

The human tear film is a highly ordered structure consisting of a thin layer of lipid on the surface and a thicker aqueous-mucin phase, which increases in mucin concentration toward the corneal epithelial cell layer. The health of the tear film and ocular surface influences the likelihood of being able to achieve successful contact lens wear. Contact lens discomfort and dryness are the most frequent reasons why contact lens wearers experience reduced wearing times, which can eventually lead to contact lens discontinuation. Comprehensive clinical assessment of tear film integrity and ocular surface health is therefore essential prior to commencing contact lens wear, to enable the ocular surface environment to be optimised to support lens wear. These parameters should also be evaluated over the course of contact lens wear, in order to identify any aspects requiring clinical management and ensure maintenance of optimal lens-wearing conditions. This review summarises current knowledge relating to the effects of soft contact lens wear on the tear film and ocular surface. It also provides a systematic approach to evaluating tear film and ocular surface integrity, in order to guide the clinical management of tear film anomalies with respect to contact lens wear.

The effect of rebamipide ophthalmic suspension on ocular surface mucins in soft contact lens wearers

PURPOSE

To evaluate the changes in ocular surface mucins with 2%rebamipide ophthalmic suspension treatment in soft contact lens (SCL) wearers. Rebamipide suspension is a mucin secretagogue approved for the treatment of dry eye syndrome in Japan. In this study, the fluorescence intensity of wheat germ agglutinin conjugate of fluorescein (F-WGA) was used as a marker of membrane-associated mucins, and sialic acid concentration in tear fluids as a marker of secreted mucins.

METHODS

Thirty-two eyes of 16 SCL wearers with discomfort were treated with rebamipide suspension at a dose of one drop in each eye four times daily for two weeks. The parameters of clinical efficacy were tear break-up time, fluorescein staining scores for the cornea and conjunctiva, and Schirmer test values. Fluorescence intensities in the central cornea were measured by fluorophotometry after the application of 5% F-WGA solution. Tears collected by Schirmer test strips were analyzed by high-performance liquid chromatography, and the concentrations of sialic acid, total protein, and the four major tear proteins, namely secretory IgA, lactoferrin, lipocalin-1, and lysozyme were measured.

RESULTS

Significant increases in F-WGA fluorescence intensities (p < 0.005) were seen in the corneal surfaces. Sialic acid concentrations increased over time; however, the differences were not statistically significant. Except for a slight increase in kerato-conjunctival staining scores (p < 0.05) and secretory IgA (p < 0.05), no other significant differences were seen among clinical parameters or tear proteins.

CONCLUSIONS

Topical application of rebamipide suspension significantly increased F-WGA intensity, a marker of membrane-associated mucins in SCL wearers.

Automatic analysis of corneal nerves imaged using in vivo confocal microscopy

Interest has grown over the past decade in using in vivo confocal microscopy to analyse the morphology of corneal nerves and their changes over time. Advances in computational modelling techniques have been applied to automate the estimation of sub-basal nerve structure. These objective methods have the potential to quantify nerve density (and length), tortuosity, variations in nerve thickness, as well as temporal changes in nerve fibres such as migration patterns. Different approaches to automated nerve analysis, methods proposed and how they were validated in previous literature are reviewed. Improved understanding of these approaches and their limitations will help improve the diagnostic leverage of emerging developments for monitoring the onset and progression of a broad class of systemic diseases, including diabetes.

A pilot study on corneal Langerhans cells in keratoconus

PURPOSE

To report the density and morphology of cells that are analogous to corneal Langerhans cells and their associations in keratoconus.

MATERIALS AND METHODS

This prospective cross-sectional study included a convenience sample of keratoconus subjects aged between 18-65 years. Corneal topography, assessment of ocular symptoms, tear variables, corneal sensitivity, in-vivo confocal microscopy were performed. The number of Langerhans cells were manually counted and averaged across three central corneal images. Cell morphology was graded on a 0-3 scale, where grade 3 indicates cells with long visible dendrites. Associations of Langerhans cells with other variables were evaluated using Spearman's correlation.

RESULTS

Twenty-one keratoconus subjects with a mean age of 43±11 years were included. Eighty-one percent of them were males, 48% had mild keratoconus and 52% were contact lens wearers. Langerhans cells were present in the central cornea in 91% of subjects. Median cell density was 15 cells/mm²(IQR: 3-21). Cell morphology of grades 2 or 3 (with short or long dendrites) was seen in 71% of subjects. There was a significant association between Langerhans cell frequency and density with male gender (rho and p-values: -0.669, 0.001 and -0.441,0.045) and between Langerhans cell density and nerve fibre tortuosity (0.479,0.028). No significant association observed with age, contact lens wear or ocular symptoms.

CONCLUSION

Langerhans cells were present in a significant number of subjects suggesting the possibility of inflammation in keratoconus. Based on the association of Langerhans cells with nerve parameters, we propose inflammation as the underlying cause for corneal nerve changes in keratoconus.