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There is a reduction in corneal nerve fiber density and length in type 2 diabetes mellitus with chronic kidney disease compared with type 2 diabetes mellitus alone; however, this difference does not result in worse ocular surface discomfort or dry eye disease.This study aimed to determine the clinical impact of corneal nerve loss on ocular surface discomfort and markers of ocular surface homeostasis in people with type 2 diabetes mellitus without chronic kidney disease (T2DM-no CKD) and those with type 2 diabetes mellitus with concurrent chronic kidney disease (T2DM-CKD).Participants were classified based on estimated glomerular filtration rates into two groups: T2DM-CKD (n = 27) and T2DM-no CKD (n = 28).There was a significant difference between the T2DM-CKD and T2DM-no CKD groups in corneal nerve fiber density (14.9 ± 8.6 and 21.1 ± 7.1 no./mm 2 , respectively; P = .005) and corneal nerve fiber length (10.0 ± 4.6 and 12.3 ± 3.7 mm/mm 2 , respectively; P = .04). Fluorescein tear breakup time was significantly reduced in T2DM-CKD compared with T2DM-no CKD (8.1 ± 4.4 and 10.7 ± 3.8 seconds, respectively; P = .01), whereas ocular surface staining was not significantly different (3.5 ± 1.7 and 2.7 ± 2.3 scores, respectively; P = .12). In terms of ocular surface discomfort, there were no significant differences in the ocular discomfort score scores (12.5 ± 11.1 and 13.6 ± 12.1, respectively; P = .81) and Ocular Pain Assessment Survey scores (3.3 ± 5.4 and 4.3 ± 6.1, respectively; P = .37) between the T2DM-CKD and T2DM-no CKD.The current study demonstrated that corneal nerve loss is greater in T2DM-CKD than in T2DM-no CKD. However, these changes do not impact ocular surface discomfort or markers of ocular surface homeostasis.

SIGNIFICANCE This cross-sectional study presented a link between contact lens wear and changes on the cellular morphology characteristics of the lid wiper (LW) epithelium, which was not visible by LW staining. PURPOSE The aim of this study was to establish if the duration of contact lens (CL) wear affects the cellular morphology of the LW epithelium. METHODS This was a cross-sectional study of 100 individuals with different exposures to CL wear: short, moderate, and long experience of CL wear; previous CL wearers; and nonwearers (NWs) as controls. Impression cytology samples were collected from the central upper lid margin (LW area). After fixing, samples were stained with periodic acid-Schiff and haematoxylin for cell morphology analysis and subsequently graded according to the Nelson 0- to 3-point scale. Lid wiper staining was assessed with the aid of lissamine green and graded using the Korb (0- to 3-point) scale. One-way Kruskal-Wallis analysis followed by the Dunn multiple-comparisons test was used for statistical comparison. RESULTS The Nelson grade for LW epithelium morphology was significantly different between groups (P = .003). Abnormal epithelial morphology as defined by grade 2 or 3 was evident in 66.7% of CL wearers with short experience and 76.5% of CL wearers with moderate experience. This was significantly higher than NWs of whom only 21.5% showed greater than grade 1 (P = .02 and .005, respectively). There was no significant difference between NWs and other groups. Lid wiper staining did not significantly differ between groups (P = .50) or correlate with the Nelson grade (Spearman r = 0.02, P = .08). CONCLUSIONS Metaplasia of the LW epithelium was significantly greater in the early to moderate stages of CL. This supports the view that mechanical irritation is responsible for LW changes in CL wear. Ceasing CL wear seems to lead to recovery. Lid wiper staining did not reflect the underlying morphological changes.

This work aims to characterize the relationship between tear film neuropeptide substance P and the structural integrity of the sub-basal nerve plexus in diabetes.Seventeen healthy control participants and nine participants with diabetes were recruited in this cross-sectional study. Total protein content and substance P concentrations were determined in the flush tears of participants. Corneal nerve morphology was assessed by capturing the corneal sub-basal nerve plexus using the Heidelberg Retinal Tomograph II with the Rostock Corneal Module (Heidelberg Engineering GmbH, Heidelberg, Germany) in the central cornea. Corneal nerve fiber density (CNFD) was measured using ACCMetrics (M.A. Dabbah, Imaging Science and Biomedical Engineering, Manchester, UK) on eight captured images. Comparisons between groups were made using independent samples t-tests. Correlations between parameters were analyzed using Pearson's correlations.Substance P concentrations were significantly higher in the tears of the control group compared to participants with diabetes (4150 ± 4752 and 1473 ± 1671 pg/mL, respectively, P = .047). There was no significant difference in total protein content between the groups (3.4 ± 1.8 and 2.6 ± 1.7 mg/mL in the control and diabetes groups, respectively, P = .262). CNFD was significantly lower in the participants with diabetes compared to the control group (16.1 ± 5.7 and 21.5 ± 7.0 mm/mm, respectively, P = .041). There was a moderate correlation between substance P and CNFD (r = 0.48, P = .01).Substance P is expressed at a significantly lower level in the tears of people with diabetes compared with healthy controls. The positive correlation between substance P and corneal nerve density indicates that substance P may be a potential biomarker for corneal nerve health.

Purpose: This study set out to determine how contact lens wear affects the profile of matrix metalloproteinase 9 (MMP-9) in the tear film. Methods: Flush tears were collected from 47 healthy neophytes before lens wear, during the first day of lens wear, and after 1 month adaptation. Participants were randomized to either Acuvue Oasys or O2OPTIX with the choice of extended (EW) or daily wear (DW). Each time, tears were collected at midday, before sleep, and on waking and analyzed for concentrations of total protein, MMP-9, and its regulators TIMP-1 (tissue inhibitor of metalloproteinases 1) and NGAL (neutrophil gelatinase-associated lipocalin). Results: Initial extended contact lens wear resulted in significantly elevated MMP-9 levels on waking (3598.7 ± 3229.1 ng/mL) compared with the same time point at baseline (2123.3 ± 1762.8; p = 0.02), whereas DW remained unchanged (2373.0 ± 2091.6 ng/mL; p = 0.61). After 1 month of EW, the levels on awakening were no longer different to those of baseline (2408.2 ± 1376.1 ng/mL; p = 0.63). The MMP:TIMP ratio during EW was greater after the first night (18.6 ± 19.9) than both no wear (13.2 ± 13.4) and 1 month (10.4 ± 7.7), but only the latter was significant (p = 0.048). The profile of NGAL did not differ from baseline (p = 0.055). Conclusions: In the neophyte, the initial period of overnight lens wear seems to disturb the tear film homeostasis, as indicated by a significant increase in MMP-9 on awakening. The return to baseline by 1 month suggests that an adaptive process takes place. No comparable changes are seen in DW. © 2013 American Academy of Optometry.

Purpose. This study evaluates the use of differential gel electrophoresis (DIGE) for tear analysis and applies this technique to establish the effect of extended contact lens wear on the tear proteome. Methods. Flush tears were collected from nine healthy non-contact lens wearers at baseline, during the first day, and after 1 month of contact lens wear. Participants wore AIR OPTIX on an extended wear (EW) schedule. Tears were collected at mid-day and upon waking and analyzed for concentrations of total protein using the bicinchoninic acid assay method. DIGE was then performed to detect biomarkers likely to be affected by contact lens wear. Technique variability, physiological variability, and the effect of EW were established. Proteins with significantly changed abundance during lens wear were cut and identified with mass spectrometry. Results. Both Cy3 and Cy5 identified the same proteins relative to Cy2 with the highest fold difference of 4.4. The proteome varied by 3% at the same time point, with a significant increase in protein spots found between mid-day (257) and upon awakening (298). With EW, of the 311 proteins spots identified upon awakening, 15 differed significantly. Of the five differences between baseline and the first night of EW, all were greater at baseline. Of the differences between baseline and 1 month, six were greater at 1 month and four were greater at baseline. Conclusions. DIGE is a repeatable proteomic technique capable of determining differences in the tear proteome. The extent of the participants' experience with lens wear is an important factor to consider when analyzing the tears from lens wearers, as neophytes appear to differ from those with experience. © 2012 American Academy of Optometry.