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.

Corneal Confocal Microscopy Predicts the Development of Diabetic Neuropathy: A Longitudinal Diagnostic Multinational Consortium Study.

OBJECTIVE: Corneal nerve fiber length (CNFL) has been shown in research studies to identify diabetic peripheral neuropathy (DPN). In this longitudinal diagnostic study, we assessed the ability of CNFL to predict the development of DPN. RESEARCH DESIGN AND METHODS: From a multinational cohort of 998 participants with type 1 and type 2 diabetes, we studied the subset of 261 participants who were free of DPN at baseline and completed at least 4 years of follow-up for incident DPN. The predictive validity of CNFL for the development of DPN was determined using time-dependent receiver operating characteristic (ROC) curves. RESULTS: A total of 203 participants had type 1 and 58 had type 2 diabetes. Mean follow-up time was 5.8 years (interquartile range 4.2-7.0). New-onset DPN occurred in 60 participants (23%; 4.29 events per 100 person-years). Participants who developed DPN were older and had a higher prevalence of type 2 diabetes, higher BMI, and longer duration of diabetes. The baseline electrophysiology and corneal confocal microscopy parameters were in the normal range but were all significantly lower in participants who developed DPN. The time-dependent area under the ROC curve for CNFL ranged between 0.61 and 0.69 for years 1-5 and was 0.80 at year 6. The optimal diagnostic threshold for a baseline CNFL of 14.1 mm/mm2 was associated with 67% sensitivity, 71% specificity, and a hazard ratio of 2.95 (95% CI 1.70-5.11; P < 0.001) for new-onset DPN. CONCLUSIONS: CNFL showed good predictive validity for identifying patients at higher risk of developing DPN ∼6 years in the future.

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.

Rapid Corneal Nerve Fiber Loss: A Marker of Diabetic Neuropathy Onset and Progression.

OBJECTIVE: Corneal nerve fiber length (CNFL) represents a biomarker for diabetic distal symmetric polyneuropathy (DSP). We aimed to determine the reference distribution of annual CNFL change, the prevalence of abnormal change in diabetes, and its associated clinical variables. RESEARCH DESIGN AND METHODS: We examined 590 participants with diabetes (399 with type 1 diabetes [T1D] and 191 with type 2 diabetes [T2D]) and 204 control patients without diabetes with at least 1 year of follow-up and classified them according to rapid corneal nerve fiber loss (RCNFL) if CNFL change was below the 5th percentile of the control patients without diabetes. RESULTS: Control patients without diabetes were 37.9 ± 19.8 years old, had median follow-up of three visits over 3.0 years, and mean annual change in CNFL was -0.1% (90% CI -5.9% to 5.0%). RCNFL was defined by values exceeding the 5th percentile of 6% loss. Participants with T1D were 39.9 ± 18.7 years old, had median follow-up of three visits over 4.4 years, and mean annual change in CNFL was -0.8% (90% CI -14.0% to 9.9%). Participants with T2D were 60.4 ± 8.2 years old, had median follow-up of three visits over 5.3 years, and mean annual change in CNFL was -0.2% (90% CI -14.1% to 14.3%). RCNFL prevalence was 17% overall and was similar by diabetes type (64 T1D [16.0%], 37 T2D [19.4%], P = 0.31). RNCFL was more common in those with baseline DSP (47% vs. 30% in those without baseline DSP, P = 0.001), which was associated with lower peroneal conduction velocity but not with baseline HbA1c or its change over follow-up. CONCLUSIONS: An abnormally rapid loss of CNFL of 6% per year or more occurs in 17% of diabetes patients. RCNFL may identify patients at highest risk for the development and progression of DSP.

Corneal Nerve Migration Rate in a Healthy Control Population.

PURPOSE: The purpose of this study was to establish an age-dependent normative range and factors affecting the migration rate of the corneal subbasal nerve plexus in a healthy control population. METHODS: Corneal nerve migration rate was measured in 60 healthy participants grouped by age: A, aged 20 to 39 years (n = 20); B, 40 to 59 years (n = 20); and C, 60 to 79 years (n = 20). Laser-scanning corneal confocal microscopy was performed on the right eye of all participants at baseline and again after 3 weeks. Fully automated software was used to montage the frames. Distinctive nerve landmarks were manually reidentified between the two montages, and a software program was developed to measure the migration of these landmark points to determine corneal nerve migration rate in micrometers per week (µm/wk). RESULTS: The mean ± SD age of all participants in the study was 47.5 ± 15.5 years; 62% of participants were male. The average corneal nerve migration rates of groups A, B, and C were 42.0 ± 14.0, 42.3 ± 15.5, and 42.0 ± 10.8 µm/wk, respectively (P = .99). There was no difference in corneal nerve migration rate between male (41.1 ± 13.5 µm/wk) and female (43.7 ± 13.2 µm/wk) participants (P = .47). There was no significant correlation between age (P = .97), smoking (P = .46), alcohol use (P = .61), and body mass index (P = .49, respectively) with corneal nerve migration rate. However, exercise frequency correlated significantly (P = .04) with corneal nerve migration rate. CONCLUSIONS: Corneal nerve migration rate varies in healthy individuals and is not affected by age, sex, or body mass index but is related to physical activity.

Corneal confocal microscopy for identification of diabetic sensorimotor polyneuropathy: a pooled multinational consortium study.

AIMS/HYPOTHESIS: Small cohort studies raise the hypothesis that corneal nerve abnormalities (including corneal nerve fibre length [CNFL]) are valid non-invasive imaging endpoints for diabetic sensorimotor polyneuropathy (DSP). We aimed to establish concurrent validity and diagnostic thresholds in a large cohort of participants with and without DSP. METHODS: Nine hundred and ninety-eight participants from five centres (516 with type 1 diabetes and 482 with type 2 diabetes) underwent CNFL quantification and clinical and electrophysiological examination. AUC and diagnostic thresholds were derived and validated in randomly selected samples using receiver operating characteristic analysis. Sensitivity analyses included latent class models to address the issue of imperfect reference standard. RESULTS: Type 1 and type 2 diabetes subcohorts had mean age of 42 ± 19 and 62 ± 10 years, diabetes duration 21 ± 15 and 12 ± 9 years and DSP prevalence of 31% and 53%, respectively. Derivation AUC for CNFL was 0.77 in type 1 diabetes (p < 0.001) and 0.68 in type 2 diabetes (p < 0.001) and was approximately reproduced in validation sets. The optimal threshold for automated CNFL was 12.5 mm/mm2 in type 1 diabetes and 12.3 mm/mm2 in type 2 diabetes. In the total cohort, a lower threshold value below 8.6 mm/mm2 to rule in DSP and an upper value of 15.3 mm/mm2 to rule out DSP were associated with 88% specificity and 88% sensitivity. CONCLUSIONS/INTERPRETATION: We established the diagnostic validity and common diagnostic thresholds for CNFL in type 1 and type 2 diabetes. Further research must determine to what extent CNFL can be deployed in clinical practice and in clinical trials assessing the efficacy of disease-modifying therapies for DSP.

Ophthalmic and clinical factors that predict four-year development and worsening of diabetic retinopathy in type 1 diabetes.

AIMS: To investigate the role of ophthalmic imaging markers - namely retinal thickness measures and corneal nerve morphology - in predicting four-year development and worsening of diabetic retinopathy (DR) in type 1 diabetes (T1DM). METHODS: 126 eyes of 126 participants with T1DM were examined at baseline and after four years. Diabetic retinopathy (DR) was graded using the Early Treatment Diabetic Retinopathy Study scale. HbA1c, nephropathy, neuropathy, cardiovascular factors, and retinal thickness using optical coherence tomography (OCT) and corneal nerve fiber length (CNFL) using corneal confocal microscopy at baseline were assessed by univariate and step-wise multiple logistic regression, and their diagnostic capabilities for single and combined measures. RESULTS: Four-year development of DR was 19% (13 of 68 without DR at baseline). Worsening of DR was seen in 43% (25 of 58 with DR at baseline). When adjusted for potential confounders, a lower CNFL (AUC=0.637, p=0.040, 64% sensitivity and 64% specificity at 14.9mm/mm2 cut-off), higher triglycerides (AUC=0.669, p=0.012, 64% sensitivity, 62% specificity at 0.85mmol/L) and an elevated vibration threshold (AUC=0.708, p=0.002, 96% sensitivity, 40% specificity at 3.55Hz) were significant predictors for four-year worsening of DR. CONCLUSIONS: Reduced CNFL, elevated vibration perception threshold and higher triglycerides can predict future worsening of DR.

Corneal and Retinal Neuronal Degeneration in Early Stages of Diabetic Retinopathy.

Purpose: To examine the neuronal structural integrity of cornea and retina as markers for neuronal degeneration in nonproliferative diabetic retinopathy (NPDR). Methods: Participants were recruited from the broader Brisbane community, Queensland, Australia. Two hundred forty-one participants (187 with diabetes and 54 nondiabetic controls) were examined. Diabetic retinopathy (DR) was graded according to the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Corneal nerve fiber length (CNFL), corneal nerve branch density (CNBD), corneal nerve fiber tortuosity (CNFT), full retinal thickness, retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), focal (FLV) and global loss volumes (GLV), hemoglobin A1c (HbA1c), nephropathy, neuropathy, and cardiovascular measures were examined. Results: The central zone (P = 0.174), parafoveal thickness (P = 0.090), perifovea (P = 0.592), RNFL (P = 0.866), GCC (P = 0.798), and GCC GLV (P = 0.338) did not differ significantly between the groups. In comparison to the control group, those with very mild NPDR and those with mild NPDR had significantly higher focal loss in GCC volume (P = 0.036). CNFL was significantly lower in those with mild NPDR (P = 0.004) in comparison to the control group and those with no DR. The CNBD (P = 0.094) and CNFT (P = 0.458) did not differ between the groups. Conclusions: Both corneal and retinal neuronal degeneration may occur in early stages of diabetic retinopathy. Further studies are required to examine these potential markers for neuronal degeneration in the absence of clinical signs of DR.

Diagnostic capability of retinal thickness measures in diabetic peripheral neuropathy / Capacidad diagnóstica de las mediciones del grosor de la retina en la neuropatía periférica diabética

Purpose: To examine the diagnostic capability of the full retinal and inner retinal thickness measures in differentiating individuals with diabetic peripheral neuropathy (DPN) from those without neuropathy and non-diabetic controls. Methods: Individuals with (n=44) and without (n=107) diabetic neuropathy and non-diabetic control (n=42) participants underwent spectral domain optical coherence tomography (SDOCT). Retinal thickness in the central 1mm zone (including the fovea), parafovea and perifovea was assessed in addition to ganglion cell complex (GCC) global loss volume (GCC GLV) and focal loss volume (GCC FLV), and retinal nerve fiber layer (RNFL) thickness. Diabetic neuropathy was defined using a modified neuropathy disability score (NDS) recorded on a 0-10 scale, wherein, NDS ≥3 indicated neuropathy and NDS indicated <3 no neuropathy. Diagnostic performance was assessed by areas under the receiver operating characteristic curves (AUCs), 95 per cent confidence intervals (CI), sensitivities at fixed specificities, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the cut-off points for the best AUCs obtained. Results: The AUC for GCC FLV was 0.732 (95% CI: 0.624-0.840, p<0.001) with a sensitivity of 53% and specificity of 80% for differentiating DPN from controls. Evaluation of the LRs showed that GCC FLV was associated with only small effects on the post-test probability of the disease. The cut-off point calculated using the Youden index was 0.48% (67% sensitivity and 73% specificity) for GCC FLV. For distinguishing those with neuropathy from those without neuropathy, the AUCs of retinal parameters ranged from 0.508 for the central zone to 0.690 for the inferior RNFL thickness. For distinguishing those with moderate or advanced neuropathy from those with mild or no neuropathy, the inferior RNFL thickness demonstrated the highest AUC of 0.820, (95% CI: 0.731-0.909, p<0.001) with a sensitivity of 69% and 80% specificity. The cut-off-point for the inferior RNFL thickness was 97μm, with 81% sensitivity and 72% specificity. Conclusions: The GCC FLV can differentiate individuals with diabetic neuropathy from healthy controls, while the inferior RNFL thickness is able to differentiate those with greater degrees of neuropathy from those with mild or no neuropathy, both with an acceptable level of accuracy. Optical coherence tomography represents a non-invasive technology that aids in detection of retinal structural changes in patients with established diabetic neuropathy. Further refinement of the technique and the analytical approaches may be required to identify patients with minimal neuropathy (AU)

Objetivo: Examinar la capacidad diagnóstica de las mediciones del grosor total e interno de la retina, con diferenciación entre individuos con neuropatía periférica diabética (DPN), aquellos que no la padecen, y controles no diabéticos. Métodos: Cuarenta y cuatro individuos con (n=44) y sin (n=107) neuropatía diabética y participantes de control no diabéticos (n=42) fueron sometidos a una tomografía de coherencia óptica de dominio espectral (SDOCT). Se evaluó el grosor de la retina en la zona central de 1mm (incluyendo la fóvea), parafóvea y perifóvea, además del complejo de células ganglionares (GCC), el volumen de pérdida global (GCC GLV) y el volumen de pérdida focal (GCC FLV), y el espesor de la capa de fibras nerviosas de la retina (RNFL). Se definió la neuropatía diabética utilizando la versión modificada del «Neuropathy Disability Score (NDS)», sobre una escala de 0 a 10, donde el valor de NDS ≥3 indicaba neuropatía y NDS <3 ausencia de la misma. El desempeño diagnóstico se evaluó mediante las áreas bajo las curvas características operativas del receptor (AUC), intervalos de confianza del 95% (IC), sensibilidades a especificidades fijas, cociente de probabilidad positiva (CP+), y cociente de probabilidad negativa (CP-) y los puntos de corte para los mejores AUC obtenidos. Resultados: El AUC para GCC FLV fue de 0,732, 95% IC: 0,624-0,840, p<0,001 con una sensibilidad del 53% y una especificidad del 80% para la diferenciación entre DPN y los controles. La evaluación de los CP reflejó que el GCC FLV se asociaba únicamente a unos pequeños efectos en la prueba posterior de probabilidad de la enfermedad. El punto de corte calculado utilizando el índice de Youden fue del 0,48% (67% de sensibilidad y 73% de especificidad) para GCC FLV. Para distinguir a aquellos individuos con neuropatía de los que no la padecían, las AUC de los parámetros retinianos oscilaron entre 0,508 para el grosor RNFL de la zona central y 0,690 para el de la zona inferior. Para distinguir a aquellas personas con neuropatía moderada o avanzada, de aquellas con neuropatía leve, o ausencia de ella, el grosor RNFL de la zona inferior reflejó una AUC superior de 0,820, 95% IC: 0,731-0,909, p<0,001, con una sensibilidad del 69% y una especificidad del 80%. El punto de corte para el grosor RNFL inferior fue de 97μm, con un 81% de sensibilidad y un 72% de especificidad. Conclusiones: El GCC FLV puede diferenciar entre aquellos individuos con neuropatía diabética y los controles sanos, mientras que el grosor RNFL de la zona inferior es capaz de diferenciar entre aquellas personas con grados superiores de neuropatía y aquellas con neuropatía leve o ausencia de neuropatía, en ambos casos con un nivel aceptable de precisión. La tomografía de coherencia óptica supone una tecnología no invasiva que ayuda a la detección de los cambios estructurales retinianos en pacientes con neuropatía diabética establecida. Se precisa un mayor refinamiento de esta técnica, así como enfoques analíticos, para identificar a aquellos pacientes con una neuropatía mínima (AU)

Presence of Peripheral Neuropathy Is Associated With Progressive Thinning of Retinal Nerve Fiber Layer in Type 1 Diabetes.

Purpose: Reduced retinal nerve fiber layer (RNFL) thickness has been demonstrated in patients with diabetic peripheral neuropathy (DPN) in cross-sectional studies. This prospective study defines longitudinal alterations to the RNFL thickness in individuals with type 1 diabetes without (DPN-ve) and with (DPN+ve) DPN and in relation to risk factors for nerve damage. Methods: A cohort of 105 individuals with type 1 diabetes (20% DPN+ve) with predominantly mild or no retinopathy and no previous retinal photocoagulation underwent spectral-domain optical coherence tomography (SD-OCT) at baseline, 2 years, and 4 years. SD-OCT scans were acquired at 3.45-mm diameter around the optic nerve head and the overall RNFL and RNFL in the nasal, superior, temporal, and inferior quadrants were quantified. By including serial quantified RNFL parameters, linear mixed models were applied to assess the change in RNFL thickness over time and to explore the associations with other clinical variables. Results: There was a significant decline in the overall RNFL thickness (-0.7 µm/y, P = 0.02) and RNFL in the superior quadrant (-1.9 µm/y, P < 0.01) in the DPN+ve group compared with DPN-ve group. The overall RNFL thickness and RNFL in the superior and nasal quadrants were inversely associated with age (ß = -0.29, -0.41, and -0.29, respectively; P ≤ 0.02). Sex, retinopathy, diabetes duration, hemoglobin A1c, lipid profile, blood pressure, cigarette use, alcohol consumption, and body mass index did not show any significant effects (P > 0.05). Conclusions: Individuals with DPN showed a progressive RNFL thinning overall and in the superior quadrant, which was more pronounced in older individuals. There may be common pathways for retinal and peripheral neurodegeneration that are independent of conventional DPN risk factors.

Optical coherence tomography predicts 4-year incident diabetic neuropathy.

PURPOSE: To examine the capability of optical coherence tomography-derived retinal thickness measures in detecting 4-year incident diabetic peripheral neuropathy (DPN). METHODS: 145 eyes of 145 participants with diabetes but no DPN at baseline were examined for incident DPN. HbA1c levels, nephropathy, neuropathy (DPN), cardiovascular measures, and various retinal thickness measures were examined at baseline and after 4 years. Incidence of DPN was defined as newly developed DPN at follow-up. Baseline factors were assessed by univariate and a step-wise multiple logistic regression, and the predictors were examined for diagnostic capabilities. RESULTS: Of the 145 participants without DPN at baseline, 51 had developed DPN when examined after 4 years (35% incidence). Of the ophthalmic variables, the mean (S.D.) of the overall thickness in the parafovea at baseline was 315 (18) µm in the no DPN group and 306 (18) µm in the 'incidence' group, and the differences were significant, p = 0.005. The superior hemisphere parafovea (mean (S.D.): 318 (17) µm vs 310 (20) µm, p = 0.02) and inferior hemisphere parafovea (313 (19) µm vs 302 (18) µm, p = 0.002) were different in the incident DPN group compared with the no DPN group. When adjusted for age, retinal thickness in the parafovea (AUC = 0.65, p = 0.003, 86% sensitivity and 44% specificity at 321 µm criterion), and body mass index or BMI (AUC = 0.65, p = 0.003, 49% sensitivity and 83% specificity at 29.3 kg m-2 criterion) at baseline were significant predictors for 4-year incident DPN. CONCLUSIONS: A lower retinal thickness at the parafovea and a higher BMI can predict 4-year incident neuropathy in patients with diabetes, with acceptable diagnostic accuracies. This OCT-derived measure may serve as a potential ophthalmic marker in the screening of patients at risk of developing DPN.

Corneal confocal microscopy best identifies the development and progression of neuropathy in patients with type 1 diabetes.

A sub-set of 38 individuals with type 1 diabetes that fulfilled a strict criterion of "normal" classification for all 7 measures of neuropathy at baseline, were identified and followed. Corneal nerve morphology, as captured with corneal confocal microscopy demonstrated the greatest, and most sustained degeneration over a 4 year period.

Diagnostic capability of retinal thickness measures in diabetic peripheral neuropathy.

PURPOSE: To examine the diagnostic capability of the full retinal and inner retinal thickness measures in differentiating individuals with diabetic peripheral neuropathy (DPN) from those without neuropathy and non-diabetic controls. METHODS: Individuals with (n=44) and without (n=107) diabetic neuropathy and non-diabetic control (n=42) participants underwent spectral domain optical coherence tomography (SDOCT). Retinal thickness in the central 1mm zone (including the fovea), parafovea and perifovea was assessed in addition to ganglion cell complex (GCC) global loss volume (GCC GLV) and focal loss volume (GCC FLV), and retinal nerve fiber layer (RNFL) thickness. Diabetic neuropathy was defined using a modified neuropathy disability score (NDS) recorded on a 0-10 scale, wherein, NDS ≥3 indicated neuropathy and NDS indicated <3 no neuropathy. Diagnostic performance was assessed by areas under the receiver operating characteristic curves (AUCs), 95 per cent confidence intervals (CI), sensitivities at fixed specificities, positive likelihood ratio (+LR), negative likelihood ratio (-LR) and the cut-off points for the best AUCs obtained. RESULTS: The AUC for GCC FLV was 0.732 (95% CI: 0.624-0.840, p<0.001) with a sensitivity of 53% and specificity of 80% for differentiating DPN from controls. Evaluation of the LRs showed that GCC FLV was associated with only small effects on the post-test probability of the disease. The cut-off point calculated using the Youden index was 0.48% (67% sensitivity and 73% specificity) for GCC FLV. For distinguishing those with neuropathy from those without neuropathy, the AUCs of retinal parameters ranged from 0.508 for the central zone to 0.690 for the inferior RNFL thickness. For distinguishing those with moderate or advanced neuropathy from those with mild or no neuropathy, the inferior RNFL thickness demonstrated the highest AUC of 0.820, (95% CI: 0.731-0.909, p<0.001) with a sensitivity of 69% and 80% specificity. The cut-off-point for the inferior RNFL thickness was 97µm, with 81% sensitivity and 72% specificity. CONCLUSIONS: The GCC FLV can differentiate individuals with diabetic neuropathy from healthy controls, while the inferior RNFL thickness is able to differentiate those with greater degrees of neuropathy from those with mild or no neuropathy, both with an acceptable level of accuracy. Optical coherence tomography represents a non-invasive technology that aids in detection of retinal structural changes in patients with established diabetic neuropathy. Further refinement of the technique and the analytical approaches may be required to identify patients with minimal neuropathy.

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

BACKGROUND: The aim was to determine longitudinal changes in Langerhans cell density (LCD) in the human cornea and conjunctiva during asymptomatic and symptomatic contact lens wear. METHODS: Twenty-five participants with contact lens-induced dry eye (CLIDE) and 35 without CLIDE (NO-CLIDE), diagnosed using a range of symptom questionnaires and objective tests (tear film break up, cotton thread tear test and corneal staining) were enrolled. The central cornea and nasal bulbar conjunctiva were examined using a Heidelberg laser scanning confocal microscope at baseline and following one, four and 24 weeks wear of daily disposable hydrogel contact lenses. Twenty-three non-contact lens-wearing controls were also examined. Langerhans cells were counted manually from randomly selected images. RESULTS: In the cornea, mean and standard error of the mean LCD was greater after one week of lens wear in CLIDE (55 ± 7 cells/mm2 ) versus NO-CLIDE (43 ± 4 cells/mm2 ) (p = 0.041) and controls (27 ± 4 cells/mm2 ) (p < 0.001). LCD was also greater in NO-CLIDE versus controls (p = 0.010). At week 4, LCD was greater in CLIDE (41 ± 6 cells/mm2 ) versus controls (27 ± 4 cells/mm2 ) (p = 0.004). There were no other significant differences between groups at weeks four or 24. In the conjunctiva, LCD was greater after one week of lens wear in CLIDE (17 ± 1 cells/mm2 ) (p = 0.003) and NO-CLIDE (17 ± 3 cells/mm2 ) (p = 0.001) versus controls (7 ± 1 cells/mm2 ). There were no significant differences between groups at weeks four or 24. CONCLUSIONS: The initial transient increase in corneal and conjunctival LCD in CLIDE (versus NO-CLIDE) suggests an inflammatory component in the aetiology of this condition.

Abnormal Anterior Corneal Morphology in Diabetes Observed Using In Vivo Laser-scanning Confocal Microscopy.

PURPOSE: To assess if diabetes alters corneal epithelial, anterior stromal and subbasal nerve plexus morphology and to determine the associations between these and other clinical variables. METHODS: A cohort of 78 participants with diabetes (39 with Type 1 and 39 with Type 2 diabetes) and 29 age-matched healthy controls underwent laser-scanning confocal microscopy of the central cornea. Intermediate cell density (ICD), basal cell density (BCD), anterior stromal cell density (ASCD), corneal nerve fiber density (CNFD) and nerve fiber length (CNFL) were quantified. RESULTS: Compared with controls, participants with diabetes showed reduced ICD (6097 ± 669 vs. 5548 ± 669 no/mm2, P<.01), BCD (8925 ± 1196 vs. 7842 ± 1040 cell/mm2, P<.01), CNFD (23.4 ± 9.1 vs. 17.5 ± 9.7 no/mm2, P<.01) and CNFL (21.0 ± 4.0 vs. 17.4 ± 4.9 mm/mm2, P<.01), with no difference in ASCD (785 ± 262 vs. 733 ± 278 cell/mm2, respectively, P=.40). None of these structural parameters were associated with type of diabetes (P>.06). Multiple regression analysis showed that ICD and BCD were inversely associated with the diabetes duration and diastolic blood pressure (P<.05) and positively associated with CNFD (P<.01). CNFD and CNFL were inversely associated with HbA1c (P<.01), while ASCD was inversely associated with age (P<.01). CONCLUSIONS: Corneal epithelial cells and subbasal nerve fibers are reduced in patients with diabetes; however, anterior stromal cells show no difference. Furthermore, abnormalities in corneal epithelial cells and nerves are interrelated and correlated with modifiable risk factors.

A rapid decline in corneal small fibers and occurrence of foot ulceration and Charcot foot.

We present clinical, neuropathy and corneal nerve morphology data in a participant with type 2 diabetes who developed diabetic foot ulceration, partial amputation and Charcot during a longitudinal observational study. While conventional measures of neuropathy did not deteriorate significantly, corneal nerve parameters showed a rapid reduction prior to the development of foot complications.

Characterization of Goblet Cells in a Pterygium Biopsy Using Laser Scanning Confocal Microscopy and Immunohistochemistry.

PURPOSE: To confirm that structures presumed to be GCs observed using laser scanning confocal microscopy (LSCM) are actually GCs. METHODS: A single tissue sample was obtained from a pterygium that was freshly excised from a 33-year-old male. After viewing what were believed to be GCs in the tissue sample using LSCM, the same sample was observed using laboratory confocal microscopy and immunohistochemistry. GCs were identified by a combination of classic morphologic appearance and the use of immunofluorescence to antibodies for mucin 5AC and cytokeratin-7. The LSCM and immunohistochemistry results were compared. RESULTS: Using LSCM, GCs were observed between 7 and 41 µm deep, at the level of the superficial basal cells of the tissue sample. GCs were estimated to have a diameter of 35-40 µm near the surface and 20-30 µm in the deeper layers. A small dark dot was visible in some GCs, indicating cell nuclei and/or the opened apical portion of cells representing the site of mucin release. GCs were more reflective and larger than the surrounding cells. Positively stained GCs in immunofluorescence showed a similar distribution pattern to those observed with LSCM. The tissue sample stained intensely for GC-specific mucin type 5AC. CONCLUSIONS: The pattern of discrete, large reflective cells observed using LSCM are likely to be GCs.

Repeatability of Measuring Corneal Nerve Migration Rate in Individuals With and Without Diabetes.

PURPOSE: To assess the repeatability of measuring the corneal nerve migration rate in individuals with and without neuropathy. METHODS: Wide-field montages of the subbasal corneal nerve plexus were generated at baseline and after 3 weeks for 14 participants. Montages were manually examined side by side to identify a referent landmark in the inferior whorl region (origin) and throughout each montage. A software program was developed to measure nerve migration of all identified points relative to the origin. Repeatability was determined by measurement of nerve migration for within observer (one researcher on 2 occasions, 5 days apart) and between observers (2 observers) within 4 different zones based on the distance from the origin and in the vertical section of the wide-field montage. The impact of images being montaged with fully automated software on repeatability was also investigated. RESULTS: The mean difference between observations 1 and 2 for observer 1 was 0.02 ± 1.3 µm/wk (P = 0.94), with an intraclass correlation coefficient (ICC) of 0.99 [95% confidence interval (CI) = 0.99-1.00], and the mean difference between observer 1 and 2 was 0.3 ± 1.2 µm/wk (P = 0.41), with an ICC of 0.99 (95% CI = 0.99-1.00). The mean difference between observations 1 (images montaged by semiautomated software) and 2 (images montaged by fully automated software) was 1.2 ± 4.9 µm/wk (P = 0.41), with an ICC of 0.96 (95% CI = 0.87-1.00). CONCLUSIONS: Measuring corneal nerve migration rate is highly repeatable for within and between observers and when using different methods of image montaging.

Time Course of Changes in Goblet Cell Density in Symptomatic and Asymptomatic Contact Lens Wearers.

PURPOSE: To investigate longitudinal changes in goblet cell density (GCD) in contact lens (CL) wearers who do and do not develop symptoms of dry eye (DE). METHODS: Sixty healthy individuals fitted with daily disposable hydrogel CLs and 23 age-balanced non-CL-wearing controls underwent assessment using the 5-item dry eye questionnaire, noninvasive tear film break-up time measurement, ocular surface assessment, and phenol red thread test evaluation. Laser scanning confocal microscopy (LSCM) and conjunctival impression cytology (CIC) were used to assess GCD at baseline and follow-up visits at 1 week and 1 and 6 months. After 1 week, all CL wearers were categorized as those who were and were not symptomatic based on responses to the CL dry eye questionnaire-8 (CLDEQ-8). A linear mixed-model was used to examine changes in GCD over time. RESULTS: The global mean GCD of the 83 participants at baseline (before CL wear) was 476 ± 41 and 467 ± 52 cells/mm2 using LSCM and CIC, respectively. After 6 months of CL wear, GCD was reduced by approximately 13% and 29% in asymptomatic (N = 29) and symptomatic (N = 17) CL wearers (all P < 0.001), respectively, observed with both LSCM and CIC. CONCLUSIONS: Contact lens wear induces a reduction of GCD over 6 months, which is exacerbated in those with DE symptoms. Either LSCM or CIC can be used to assess GCD in the conjunctiva.

Inflammatory Cell Upregulation of the Lid Wiper in Contact Lens Dry Eye.

PURPOSE: To determine if Langerhans cells in the lid wiper are upregulated in contact lens-induced dry eye (CLIDE). METHODS: The lid wiper of one eye of 17 participants with CLIDE (assessed using the CLDEQ-8) and 29 without CLIDE (NO-CLIDE) was examined using a Heidelberg laser scanning confocal microscope after 6 months wear of daily disposable hydrogel contact lenses (Biomedics 1 day Extra). Twenty non-contact-lens-wearing controls were also examined. Langerhans cell density (LCD) in each participant was taken as the mean cell count calculated manually from six clear, randomly selected images of known dimensions. RESULTS: There were significant overall differences in LCD in the lid wiper among the three groups (p < 0.001). LCD was significantly greater in the lid wiper in CLIDE (17 ± 10 cells/mm) compared to controls (8 ± 4 cells/mm) (p < 0.001); however, there was no difference in LCD between NO-CLIDE (10 ± 5 cells/mm) and controls (p = 0.489). LCD was significantly greater in CLIDE than NO-CLIDE (p = 0.002). CONCLUSIONS: Langerhans cells in the lid wiper are upregulated in CLIDE, suggesting an inflammatory component in the etiology of this condition.