Nerve Plexus Density Research Articles

Analysis of the mucosal chemokines CCL28, CXCL14, and CXCL17 in dry eye disease: An in vitro and clinical investigation

Mucosal chemokines have antimicrobial properties and play an important role in mucosal immunity. However, little is known about their expression on the ocular surface. This study aimed to analyze the expression of the mucosal chemokines CCL28, CXCL14 and CXCL17 in corneal and conjunctival epithelial cells under in vitro dry eye (DE) conditions, and in conjunctival samples from healthy subjects and DE patients. Human corneal epithelial cells (HCE) and immortalized human conjunctival epithelial cells (IM-HConEpiC) were incubated under hyperosmolar (400–500 mOsM) or inflammatory (TNF-α 25 ng/mL) conditions for 6 h and 24 h to measure CCL28, CXCL14, and CXCL17 gene expression by RT-PCR and their secretion by immunobead-based analysis (CCL28, CXCL14) and ELISA (CXCL17). Additionally, twenty-seven DE patients and 13 healthy subjects were included in this study. DE-related questionnaires (OSDI, mSIDEQ and NRS) evaluated symptomatology. Ocular surface integrity was assessed using vital staining. Tactile sensitivity was measured with Cochet-Bonnet esthesiometer, and mechanic and thermal (heat and cold) sensitivity using Belmonte's non-contact esthesiometer. Subbasal nerve plexus and dendritic cell density were analyzed by in vivo confocal microscopy. Conjunctival cells from participants were collected by impression cytology to measure mucosal chemokines gene expression by RT-PCR. Our results showed that HCE and IM-HConEpiC cells increased CCL28, CXCL14, and CXCL17 secretion under hyperosmolar conditions. The gene expression of CCL28 was significantly upregulated in conjunctival samples from DE patients. CCL28 expression correlated positively with symptomatology, corneal staining, heat sensitivity threshold, and dendritic cell density. CXCL14 expression correlated positively with age, ocular pain, conjunctival staining, tactile sensitivity, and image reflectivity. CXCL17 expression correlated positively with corneal staining. These results suggest that corneal and conjunctival epithelial cells could be a source of CCL28, CXCL14, and CXCL17 on the ocular surface and that CCL28 might be involved in DE pathogenesis.

Dexpanthenol/sodium hyaluronate eye drops for corneal epithelial healing following corneal cross-linking in patients with keratoconus.

To evaluate the effect of dexpanthenol 2%/sodium hyaluronate 0.15% eye drops on corneal epithelial healing and corneal microstructural changes following corneal cross-linking (CXL) in patients with keratoconus. The study included 42 eyes of 21 patients with keratoconus who underwent CXL on both eyes. One eye of each patient was instilled dexpanthenol 2%/sodium hyaluronate 0.15% eye drops (DP/SH group) and the fellow eye was instilled unpreserved sodium hyaluronate 0.15% eye drops (SH group). The epithelial healing process was assessed every day until complete reepithelialization was achieved. The in vivo confocal microscopy (IVCM) findings were also recorded. The mean epithelial defect size 48.6 ± 6.7 mm2 for the DP/SH group and 48.2 ± 5.3 mm2 for the SH group. Complete reepithelialization was seen after 2.24 ± 0.44days (range 2-4days) in the DP/SH group and 3.43 ± 0.60days (3 to 5days) in the SH group. Posterior keratocyte density and endothelial cell density were similar in both groups. The mean subbasal nerve plexus density was significantly higher in the DP/SH group (postoperative 1month: 1.13 ± 1.51, 3months: 3.53 ± 2.55, 6months: 7.07 ± 1.42) compared to the SH group (postoperative 1month: 0.87 ± 1.43, 3months: 2.89 ± 2.62, 6months 6.33 ± 1.29). The DP/SH group revealed faster subbasal nerve regeneration and less edema compared to the SH group. Dexpanthenol 2%/sodium hyaluronate 0.15% eye drops were effective and safe for corneal epithelial healing, and promoted faster corneal reepithelialization, nerve regeneration, and keratocyte repopulation with reduced corneal edema compared to sodium hyaluronate eye drops.

Pre-Ophthalmoscopic Quantitative Biomarkers in Diabetes Mellitus.

The purpose of this study was to assess whether retinal microvascular or corneal nerve abnormalities occur earlier in diabetes mellitus (DM) and to identify imaging biomarkers in order to help prevent the subsequent irreversible retinal and corneal complications. The study comprised 35 eyes of 35 healthy volunteers and 52 eyes of 52 patients with type 1 and type 2 DM. Swept-source optical coherence tomography (OCT), OCT angiography, and in vivo corneal confocal microscopy were performed in both groups. Corneal sub-basal nerve plexus and vessel density (VD) of superficial capillary plexus (SCP) and deep capillary plexus (DCP) were evaluated. All corneal sub-basal nerve fiber parameters were decreased in patients with DM compared with healthy subjects and the difference was significant for each result except for nerve fiber width (P = 0.586). No significant correlation was obtained between any nerve fiber morphology parameters and disease duration or HbA1C. VD in SCP was significantly decreased in the superior (P < 0.0001), temporal (P = 0.001), and nasal quadrant (P = 0.003) in the diabetes group. In DCP, only superior VD (P = 0.036), decreased significantly in the diabetes group. Ganglion cell layer thickness in the inner ring showed a significantly lower value in patients with DM (P < 0.0001). Our results implicate a more pronounced and earlier damage to the corneal nerve fibers compared to the retinal microvasculature in patients with DM. In DM, an earlier and more pronounced damage to the corneal nerve fibers was observed compared to the retinal microvasculature.

Corneal Confocal Analysis after Scleral Lens Wear in Keratoconus Patients: A Pilot Study.

Scleral lenses rely on the scleroconjunctival region without bearing the cornea, which could improve the symptoms and modify the corneal nerve plexus morphology. This study aimed to evaluate symptoms and changes in corneal nerve plexus morphology and density of Langerhans cells in keratoconus patients with and without intrastromal corneal ring before and after scleral lens wear. Sixteen scleral lens wearers with keratoconus were recruited for this short-term experimental pilot study. Subjects were divided into two groups: keratoconus group and intrastromal corneal ring segment group. All subjects were examined in two visits: baseline (before scleral lens wear) and after 6 months of scleral lens wear, after lens removal. The Schirmer I test, the Ocular Surface Disease Index, tear breakup time, and in vivo confocal microscopy were evaluated. The mean age was 42.33 ± 11.27 years. A significant decrease in tear breakup time was found in the total group ( P = .01, Wilcoxon) compared with baseline. Ocular Surface Disease Index score had decreased after 6 months of scleral lens wear in the keratoconus with intrastromal corneal ring segment subgroup ( P = .03, Wilcoxon) and in the total group ( P = .001, Wilcoxon). No statistical changes in nerve density, tortuosity, and ramification were found for either the total group or the subgroup. However, the mean nerve length was higher in all groups, especially in the keratoconus subgroup ( P = .03, Wilcoxon) after 6 months of scleral lens wear. Regarding optical density, the total group showed a significant increase after 6 months of wearing ( P = .02, Wilcoxon). Finally, Langerhans cell density was not statistically different in any group. These results suggest that scleral lens wearing improves the symptoms and increased the mean length nerves after 6 months of wear use in keratoconus patients.

Alterations in the ocular surface and tear film following keratoplasty

The purpose of this study was to evaluate any alterations in the tear film and ocular surface beyond the early postoperative period following penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK). This cross-sectional, contralateral-eye study compared ocular surface and tear film parameters of eyes with a previous PK or DALK in one eye and no prior surgery in the contralateral eye. Overall, 14 (87.5%) participants underwent PK, and 2 (12.5%) underwent DALK using a mechanical dissection. The median time from surgery was 3.4 years (range 1.5 to 38.7 years). The indication for unilateral keratoplasty was keratoconus in 15 (94%) participants, and corneal scarring in 1 (6%) eye, secondary to microbial keratitis. Operated eyes exhibited poorer non-invasive tear film breakup time, lower corneal sensitivity, lower sub-basal nerve density and more severe fluorescein staining scores than unoperated fellow eyes (all Q < 0.05). There were no significant differences in tear film lipid layer quality, tear meniscus height, conjunctival hyperaemia, lissamine green staining score, or meibography grade between operated and fellow eyes (all Q ≥ 0.20). Higher corneal esthesiometry threshold (lower corneal sensitivity) was correlated with shorter non-invasive tear film breakup time (Spearman’s rho = − 0.361, p = 0.04) and increased fluorescein staining score (Spearman’s rho = 0.417, p = 0.02). Keratoplasty can induce persistent changes in the ocular surface and tear film, including: increased fluorescein staining, decreased tear film breakup time, decreased corneal sub-basal nerve plexus density, and reduced corneal sensitivity.

In vivo confocal microscopic study of corneal innervation in Sjögren's Syndrome with or without small fiber neuropathy

PurposeTo study changes in the subbasal nerve plexus by In vivo confocal microscopy (IVCM) in Sjögren's Syndrome (SS) with or without associated Small Fiber Neuropathy (SFN), in order to prevent diagnostic delay. MethodsSeventy-one patients with SS, including 19 with associated SFN, 20 healthy volunteers and 20 patients with Meibomian gland dysfunction (MGD) were included in this retrospective case-control study. IVCM was used to investigate subbasal nerve plexus density and morphology. ResultsCorneal sensitivity as evaluated with the Cochet-Bonnet aesthesiometer was significantly reduced in the SS group versus the control group (P = 0.026) and the MGD group (P = 0.037). The number of inflammatory cells was significantly increased in the SS group to 86.2 ± 82.1 cells/mm2 compared to the control group (P < 0.001). The density of the subbasal nerve plexus was significantly reduced to 16.7 ± 6.5 mm/mm2 in the SS group compared to the control group (P < 0.005) and the MGD group (P = 0.042). The tortuosity of the nerves in the SS group was significantly increased compared to the control group (P < 0.001) and the MGD group (P = 0.025). The average number of subbasal nerve plexus neuromas was significantly increased in the SS group compared to the control group (P = 0.001), with a significant increase in the average number of neuromas in SS patients with associated SFN compared to SS patients without SFN (P = 0.008). ConclusionIVCM can be useful to detect corneal nerve changes in SS patients and may allow earlier diagnosis of the disease and to consider new therapeutic approaches.

Validation of IVCM In Measuring Sub-Basal Nerve Plexus and Keratocyte Cell Density in Corneal Wound Healing

Introduction: This study aimed to evaluate the reliability measurement of corneal stromal thickness, sub-basal nerve plexus (SBNP) and keratocyte cell density (KCD) in laser refractive surgery patients. Methods: 120 eyes of 60 participants were recruited and both right and left eyes of the myopic subjects were measured separately. Cornea stromal thickness were measured based on the cellular morphology that differs between each corneal layer. Measurement of SBNP and KCD were done using in-vivo confocal microscopy (IVCM) using corneal stromal thickness as reference. Corneal nerve parameters measured includes nerve fiber density (NFD), nerve branch Density (NBD) and nerve fiber length (NFL) while KCD were measured based the amount per area, depending on the region of interest. All images were captured and processed using ImageJTM Software and NeuronJ. All data were expressed in mean and standard deviation. Statistical analyses were performed using Predictive analytics software. P &lt; 0.05 was set as the level of significance. Intra- and inter-observer intraclass correlation analysis were done to evaluate reliability of measurement in corneal stromal thickness, SBNP and KCD. Results: This study found no significant difference between measurements for corneal stromal thickness, SBNP and KCD measured. (All P &gt; 0.05). Intraclass correlation analysis showed both intra- and inter-observer performance were approximately consistent and reliable (All r &gt; 0.90, P &gt; 0.05). Conclusion: Measurement of corneal stromal thickness, SBNP and KCD using IVCM is valid and reliable.

Bilateral Limbal Stem Cell Alterations in Patients With Unilateral Herpes Simplex Keratitis and Herpes Zoster Ophthalmicus as Shown by In Vivo Confocal Microscopy.

PurposeThe purpose of this study was to investigate the limbal changes in the palisades of Vogt (POV) in patients with herpes simplex keratitis (HSK) and herpes zoster ophthalmicus (HZO) with the application of in vivo confocal microscopy (IVCM).MethodsWe enrolled 35 eyes of 35 consecutive patients with HSK and 4 patients with HZO in this observational study. Thirty-five participants were also recruited from a healthy population as the control group. All subjects were examined by IVCM in addition to routine slit-lamp biomicroscopy. The IVCM images of the corneal basal epithelial cells, corneal nerve, and the corneoscleral limbus were acquired and then were analyzed semiquantitatively.ResultsThe rate of absent and atypical POV was significantly higher in the affected eyes of patients with HSK than in the contralateral eyes and eyes of controls (88.57% vs. 65.71% vs. 17.14%, P < 0.01). In the HZO group, the rate of absent and atypical POV was 100% in the affected eyes and 50% in the contralateral eyes. When compared to the contralateral unaffected eyes and control eyes, the average density of the central basal epithelial cells and the sub-basal nerve plexus density and the total number of nerves in the central area of the affected eyes were significantly lower in the HSK group (1541 ± 704.4 vs. 2510 ± 746.8 vs. 3650 ± 746.1 cells/mm2, P < 0.0001). Spearman's rank correlation showed that the presence of absent and atypical POV had a significant negative correlation with central corneal basal epithelial cells (rs = −0.44979, P < 0.0001), the density of total nerves (rs = −0.49742, P < 0.0001), and the total nerve numbers (rs = −0.48437, P < 0.0001). A significant positive correlation was established between the presence of absent and atypical POV and HSK severity in affected eyes in the superior, inferior, nasal, and temporal quadrants (rs = 0.68940, rs = 0.78715, rs = 0.65591, and rs = 0.75481, respectively, P < 0.0001) and the contralateral eyes (rs = 0.51636, rs = 0.36207, rs = 0.36990, rs = 0.51241, correspondingly, P < 0.0001).ConclusionsBoth eyes of patients with unilateral HSK and HZO demonstrated a profound and significant loss of limbal stem cells, which may explain the fact that HSK and HZO are risk factors for limbal stem cell deficiency (LSCD) in both eyes. The loss of LSCs was strongly correlated with the sub-basal nerve plexus and central basal epithelial cell alterations as shown by IVCM.

Impact of corneal parameters, refractive error and age on density and morphology of the subbasal nerve plexus fibers in healthy adults

The purpose of this study was to analyze corneal sub-basal nerve plexus (SBNP) density and morphology and their relationships with corneal parameters and refractive status. In this single center study, in vivo confocal microscopy (IVCM) was performed in 76 eyes of 38 healthy subjects aged 19–87 (mean age 34.987 ± 1.148). Nerve fiber analysis was performed using Confoscan 4 microscope with semi-automated software (Nidek Technologies, Italy) The nerve fiber length (NFL) µm/mm2, nerve fiber density (NFD) no./mm2, tortuosity coefficient (TC), and nerve beadings density (NBD) no./mm were considered. Relationship between SBNP parameters and corneal curvature, thickness, diameter, and refraction were analyzed. Additionally, the association with gender, laterality and age were determined. NFL was inversely correlated with age (r = − 0.528, p < 0.001), myopic refractive error (spherical value) (r = − 0.423, p < 0.001), and cylindrical power (r = − 0.340, p = 0.003). NFD was inversely correlated with age (r = − 0.420, p < 0.001) and myopic refractive error (r = − 0.341, p = 0.003). NBD showed a low inverse correlation with cylindrical power (r = − 0.287, p = 0.012) and a slight positive correlation with K (r = 0.230, p = 0.047). TC showed a significant negative correlation between age (r = − 0.500, p < 0.001) and myopic refractive error (r = − 0.351, p = 0.002). Additionally, there were strong positive correlations between NFL and NFD (r = 0.523, p < 0.001), NFL and TI (r = 0.603, p < 0.001), and NFD and TC (r = 0.758, p < 0.001). Multiple regression analysis revealed age to be the most significant factor affecting SBNP density (B = − 0.467, p = 0.013) and length (B = − 61.446, p < 0.001); myopic refractive error reduced both SBNP density (B = − 2.119, p = 0.011) and length (B = − 158.433, p = 0.016), while gender and laterality had no significant effects (p > 0.005). SBNP fiber length decreases with age, myopic refractive error and cylindrical power. SBNP fiber density reduces with age and myopic refractive error. Corneal nerve parameters are not influenced by gender or laterality.

The Association between Meibomian Gland Atrophy and Corneal Subbasal Nerve Loss in Patients with Chronic Ocular Graft-versus-host Disease

ABSTRACT Purpose: To investigate the association between meibomian gland (MG) loss and corneal subbasal nerve plexus density in patients with chronic graft-versus-host disease (GVHD) related dry eye disease (DED). Materials and Methods: This cross-sectional study included 22 adult patients with severe DED secondary to chronic GVHD. Control group comprised age- and sex-matched 28 healthy subjects with no evidence of ocular disease. All subjects underwent tear breakup time (TBUT), corneal staining, Schirmer I test without anesthesia, quantitative MG drop-out assessment using infrared meibography and corneal subbasal nerve density measurements with in vivo confocal microscopy (IVCM) (ConfoScan4, Nidek, Japan). One eye per patient was included for statistical purposes. Mann–Whitney U test and one-way multivariate ANOVA test were used for comparative analyses. Results: Compared to healthy subjects (mean age = 26.9 ± 13.5 years (range = 20–44 years)), patients with chronic GVHD (mean age = 29.6 ± 12.6 years (range = 19–45 years)) had worse meibography scores (p < .001), reduced corneal subbasal nerve plexus densities (p < .001), lower TBUT scores (p = .012), lower Schirmer I values (p = .001) and higher corneal staining scores (p = 003). Meiboscores in the GVHD and control groups were 2.9 ± 1.1 (range = 1–4) vs. 0.7 ± 0.4 (range = 0–2) for the superior (p < .001), and 3.2 ± 1.2 (range = 2–4) vs. 0.5 ± 0.3 (range = 0–2) for inferior (p < .001) eyelids, respectively. Corneal subbasal nerve densities of patients with GVHD did not reveal a correlation with meiboscores (r = 0.030; p = .709 for the inferior and r = 0.268; p = .075 for the superior eyelids) but showed a weak correlation with Schirmer I test values (r = 0.268; p = .014). Conclusions: Patients with chronic GVHD are at high risk for developing DED and MG dysfunction. In the setting of chronic GVHD-related DED, MG loss does not appear to be a significant factor for corneal subbasal nerve damage.

In Vivo Confocal Microscopy of Stromal Lenticule Addition Keratoplasty for Advanced Keratoconus.

To investigate the in vivo corneal microscopic changes after femtosecond laser-assisted stromal lenticule addition keratoplasty in keratoconus by means of in vivo confocal microscopy. Patients affected by advanced keratoconus were included in the study. Negative meniscus-shaped stromal lenticules, produced with a femtosecond laser (VisuMax; Carl Zeiss Meditec) from eye bank corneas were transplanted into a stromal pocket dissected in the recipient cornea at a depth of 120 µm. In vivo confocal microscopy was performed during the 12-month follow-up to investigate changes of the corneal and lenticule structure. Ten patients were enrolled in the study. No changes of the dendritic cell population were documented during the follow-up period. Mild edema and stromal keratocyte activation gradually decreased during the first month. Subbasal nerve density returned to preoperative values after 6 months. Donor-recipient interfaces appeared hyperreflective but gradually improved over time with significantly reduced reflectivity after 3 months. No evidence of stromal inflammatory cell migration or matrix opacification was observed. Endothelial and keratocyte density remained stable over time. A variable degree of stromal radially distributed folds, not visible on biomicroscopy, was observed in the lenticule and in the posterior recipient stroma. Stromal lenticule addition keratoplasty produces transitory nerve plexus density reduction and minor inflammatory reaction that rapidly decreases during the first month. Donor-recipient interface reflectivity is comparable to a femtosecond laser refractive procedure with no sign of stromal opacification or stromal rejection in 1 year of follow-up. [J Refract Surg. 2020;36(8):544-550.].

The neuroregenerative effects of topical decorin on the injured mouse cornea

BackgroundThe cornea is innervated with a rich supply of sensory nerves that play important roles in ocular surface health. Any injury or pathology of the corneal nerves increases the risk of dry eye disease and infection. This study aims to evaluate the therapeutic potential of topical decorin to improve corneal nerve regeneration in a mouse model of sterile epithelial abrasion injury.MethodsBilateral central corneal epithelial abrasions (2-mm, Alger Brush) were performed on young C57BL/6 J mice to remove the corneal sensory nerves. Decorin, or vehicle, was applied topically, three times per day for 1 week or every 2 h for 6 h. Spectral-domain optical coherence tomography was performed to measure the abrasion area and corneal thickness. Wholemount immunofluorescence staining was used to assess sensory nerve regeneration (β-tubulin III) and immune cell density (CD45, Iba1, CD11c). To investigate the specific role of dendritic cells (DCs), Cx3cr1gfp/gfp mice, which spontaneously lack resident corneal epithelial DCs, were also investigated. The effect of prophylactic topical administration of recombinant human decorin (applied prior to the abrasion) was also investigated. Nerve tracing (NeuronJ software) was performed to compare recovery of basal nerve axons and superficial nerve terminals in the central and peripheral cornea.ResultsAt 6 h after injury, topical decorin application was associated with greater intraepithelial DC recruitment but no change in re-epithelialisation or corneal thickness, compared to the vehicle control. One week after injury, sub-basal nerve plexus and superficial nerve terminal density were significantly higher in the central cornea in the decorin-treated eyes. The density of corneal stromal macrophages in the decorin-treated eyes and their contralateral eyes was significantly lower compared to saline-treated corneas. No significant improvement in corneal nerve regeneration was observed in Cx3cr1gfp/gfp mice treated with decorin.ConclusionsDecorin promotes corneal epithelial nerve regeneration after injury. The neuroregenerative effect of topical decorin was associated with a higher corneal DC density during the acute phase, and fewer macrophages at the study endpoint. The corneal neuroregenerative effects of decorin were absent in mice lacking intraepithelial DCs. Together, these findings support a role for decorin in DC-mediated neuroregeneration following corneal abrasion injury.

Hyperglycemia Suppresses Age-Related Increases in Corneal Peripheral Sensory Nerves in Wistar Bon Kobori (WBN/Kob) Rats.

Nerve fiber density in the cornea is an alternative marker for diabetic peripheral neuropathy combined with intraepidermal nerve fiber density (IENFD). Recent studies investigated corneal nerves using rodent models of diabetes. Male Wistar Bon Kobori (WBN/Kob) rats spontaneously develop long-lasting diabetes and human-like diabetic peripheral neuropathy with vascular lesions. This study investigated corneal nerve fiber density and IENFD in diabetic male WBN/Kob rats as morphological markers of diabetic peripheral neuropathy. Male WBN/Kob rats exhibit abnormal glucose tolerance and diabetes at approximately 30 weeks of age, which progresses until approximately 90 weeks of age. Male WBN/Kob rats aged 36 and 90 weeks were therefore used for histological investigations and compared with age-matched nondiabetic female rats. Terminal epithelial nerve density and subbasal nerve plexus density in the central cornea were significantly greater in nondiabetic female rats aged 90 weeks when compared with nondiabetic female rats aged 36 weeks. However, terminal epithelial nerve density and subbasal nerve plexus density did not increase with age in diabetic male WBN/Kob rats, instead lowering by up to 40%, relative to measurements in nondiabetic female rats aged 90 weeks. However, this difference was not statistically significant. IENFD was significantly lower in diabetic male rats aged 90 weeks than in male rats aged 36 weeks, but did not differ between diabetic male rats and nondiabetic female rats aged 90 weeks. In WBN/Kob rats, hyperglycemia suppresses an age-related increase in peripheral sensory corneal nerve density; therefore, corneal sensory nerves may be important morphological markers of diabetic peripheral sensory neuropathy.

Extended Duration of Hyperglycemia Result in Human-Like Corneal Nerve Lesions in Mice With Alloxan- and Streptozotocin-Induced Type 1 Diabetes.

Previous experimental studies assessing corneal nerves as a measure of the severity of diabetic peripheral neuropathy have yielded discordant results; this may have been due to the effect of the short duration of the induced diabetes. We investigated whether increases in the duration of hyperglycemia result in the development of corneal lesions in a mouse model of alloxan (AL)- or streptozotocin (STZ)-induced type 1 diabetes. We further determined whether corneal nerve fiber density, intraepidermal nerve fiber density (IENFD), and sural nerve morphology can be used as morphologic markers of diabetic peripheral neuropathy in rodent models. A total of 30 female ICR mice were divided into three groups: those with STZ-induced (STZ group) and AL-induced (AL group) diabetes, and a control group. Hyperglycemia was maintained in diabetic mice for 35 weeks. Animals were euthanized at 41 weeks of age. Subbasal nerve plexus density (SBNPD) and terminal epithelial nerve density (TEND) in the cornea, as well as IENFD, were significantly lower, and mean sural nerve axon sizes were smaller in mice in the STZ and AL groups than in the control group. There were significant correlations between IENFD and SBNPD, and between IENFD and TEND. These results indicate that the TEND and SBNTD of the cornea may be useful morphologic markers for diabetic peripheral neuropathy.

Tear Meniscus and Corneal Sub-basal Nerve Plexus Assessment in Primary Sjögren Syndrome and Sicca Syndrome Patients.

To evaluate lower tear meniscus and corneal sub-basal nerve plexus in primary Sjögren's syndrome (pSS) and Sicca syndrome patients. Cross-sectional study of 116 patients with Sicca syndrome associated with pSS and not associated with Sjögren's syndrome (non-SS Sicca) and 20 normal control subjects. Tear meniscus height and area were measured using anterior segment optical coherence tomography; corneal sub-basal nerve plexus density, length, and tortuosity were evaluated using in vivo confocal microscopy. Data analysis was performed using IBM-SPSS Statistics 24.0. Corneal sub-basal nerve plexus density and length were significantly lower, and tortuosity was significantly higher in pSS and non-SS Sicca groups than in normal control subjects (P < 0.001; P = 0.018, respectively). Corneal sub-basal nerve plexus presented a strong association with Schirmer test I and tear breakup time. Cutoff values of sub-basal nerve plexus density (36.5 nerve/mm) and length (12.5 mm/mm) presented 80.2% to 81.9% sensitivity and 85% specificity for detecting Sicca syndrome patients. No significant differences were found between the 3 groups regarding tear meniscus height and area. Corneal sub-basal nerve plexus in vivo confocal microscopy may be a useful tool in the assessment of dry eye disease in Sicca syndrome, complementing the information provided by the conventional modalities used in dry eye disease evaluation.

In vivo confocal microscopy indicates an inverse relationship between the sub-basal corneal plexus and the conjunctivalisation in patients with limbal stem cell deficiency

Background/aimsLimbal stem cell deficiency (LSCD) is characterised by a marked decrease in limbal stem cells. It is classified primarily using subjective slit-lamp observations. In vivo confocal microscopy (IVCM) can non-invasively...

Epithelial changes with corneal punctate epitheliopathy in type 2 diabetes mellitus and their correlation with time to healing

BackgroundTo study basal epithelial cell (BEC), sub-basal nerve plexus (SBN) and Langerhans cell (LC) density in patients with type 2 diabetes mellitus (T2DM) with corneal punctate epitheliopathy (CPE) and to assess their association with time to healing of CPE.MethodsRetrospective study of in vivo confocal microscopy (IVCM) in 160 eyes from 160 patients with T2DM diagnosed with CPE due to a single cause. Key exclusion criteria included multiple-causes for CPE or treatment with autologous serum. A total of 149 eyes from 149 gender- age- and aetiolgy-matched patients with CPE without T2DM comprised the control group. Electronic records were reviewed for demographic features, history of T2DM and aetiology of CPE. Density of BEC, SBN and LC were compared between the two groups.ResultsThe healing time in days for CPE with different aetiologies in the T2DM and control groups were as follows: dry eye (21.56 ± 2.41; 7.00 ± 2.19; P = 0.001); meibomian gland dysfunction (26.42 ± 6.04; 9.21 ± 2.55; P = 0.001); cataract extraction (38.00 ± 19.62; 25.83 ± 11.49; P = 0.043); drug induced (53.19 ± 18.83; 41.86 ± 23.87; P = 0.018) and exposure (38.25 ± 14.13; 29.00 ± 13.67; P = 0.026). LC density was 38.70 ± 9.65 cells/mm2 in the T2DM group comparedwith 25.53 ± 3.54 cells/mm2 in the controls (P = 0.001). SBN density was 11.76 ± 1.69 mm/mm2 in the T2DM group compared with 20.92 ± 1.43 mm/mm2 in the controls (P = 0.001). BEC density in the T2DM group was 4982 ± 1178 cells/mm2 compared with 5739 ± 394 cells/mm2 in the control group (P = 0.018). Age and duration of T2DM had no relationship with healing time (multiple linear regression, P = 0.618; P = 0.787). The density of LC in the T2DM group showed a negative correlation with SBN density (r = 0.350; R2 = 0.1225; P = 0.034). The density of SBN in the T2DM group showed a positive correlation with BEC density (r = 0.427; R2 = 0.1823; P = 0.008). The density of BEC in the T2DM group showed a negative correlation with healing time (r = 0.931; R2 = 0.8668; P = 0.001).ConclusionsUtilising IVCM, we have demonstrated increased LC and decreased SBN in patients with T2DM and CPE. Both may be related to lower BEC density and nuclei enhanced reflection. Furthermore, decreased BEC density may lead to delay in cornea epithelium healing in the T2DM group comparedwith controls. An immune-mediated response may play a role in delayed wound closure in patients with T2DM.

Early central and peripheral corneal microstructural changes in type 2 diabetes mellitus patients identified using in vivo confocal microscopy: A case-control study.

The aim of this study was to find early central and peripheral corneal microstructural changes in healthy subjects and type 2 diabetes mellitus (T2DM) patients with/without cornea fluorescein dot staining.This is a prospective case-control study of T2DM patients with/without cornea fluorescein dot staining. Age, sex, duration of diabetes, and serum glycosylated hemoglobin A1c (HbA1c) levels were recorded. Keratograph 5 M (K5 M) and in vivo confocal microscopy were performed on all subjects. The cornea was divided into 5 zones: central, superior, temporal, nasal, and inferior. Basal epithelial cell (BEC) density, the area of BEC, sub-basal nerve plexus (SBN) density, Langerhans cell (LC), and endothelial cell (EC) density were quantitatively analyzed.This study included a total of 87 individuals (28 males and 59 females; mean age, 62.30 ± 9.93 years) with T2DM, without (n = 48; T2DM group 1) and with (n = 39; T2DM group 2) cornea fluorescein staining, as well as 51 age- and sex-matched healthy subjects (18 males and 33 females; mean age, 61.53 ± 10.15 years). Ocular Surface Disease Index scores, Schirmer Ι test, tear meniscus height, the first breakup of tear film occurrence (NIKBUT-first), and the average time of all breakup incidents (NIKBUT-average) values were significantly lower for the T2DM groups than for the healthy group. The corneal sensations of all cornea positions in the T2DM groups were significantly different from the control group. The HbA1c in the T2DM groups showed a negative correlation with central BEC density (R = 0.348, P = .015; R = 0.91, P = .001); there was no correlation of HbA1c with BEC density in the control group. The BEC density, the area of BEC, SBN, and LC density of T2DM group 1 and T2DM group 2 were significantly different compared with the control group in all corneal positions (P < .001). The BEC density of T2DM group 2 was significantly different from T2DM group 1 in the central (P = .044) and inferior (P = .013) zones. The area of BEC in T2DM group 2 was significantly different from T2DM group 1 in inferior zone (P = .014) and other corneal positions showed was no significant difference (P > .05). The SBN density of T2DM group 2 was not significantly different from T2DM group 1 in all corneal positions (P > .05). The LC density of T2DM group 2 was significantly different from T2DM group 1 in the central (P = .006) and inferior (P = .006) zones. Although the LC density in the T2DM groups showed no significant difference in all corneal zones (P > .05), the LC density in the central zone was significantly lower compared with the peripheral zone in the control group (P = .001). The central ECs in the 3 groups were not significantly different (P > .05).LC induced an immune-mediated contribution to corneal nerve damage and may influence the early stages of BEC proliferation and differentiation in T2DM. BEC density was the reliable index for evaluating the early condition of diabetic corneal epitheliopathy. The BEC density of the central and inferior corneal zones was more sensitive.

Corneal nerve microstructure in Parkinson’s disease

Ocular surface changes and blink abnormalities are well-established in Parkinson’s disease. Blink rate may be influenced by corneal sub-basal nerve density, however, this relationship has not yet been investigated in Parkinson’s disease. This case-control study examined the ocular surface in patients with moderately severe Parkinson’s disease, including confocal microscopy of the cornea. Fifteen patients with moderately severe Parkinson’s disease (modified Hoehn and Yahr grade 3 or 4) and fifteen control participants were recruited. Ophthalmic assessment included slit-lamp examination, blink rate assessment, central corneal aesthesiometry and in vivo corneal confocal microscopy. The effect of disease laterality was also investigated. Of the 15 patients with Parkinson’s disease, ten were male and the mean age was 65.5±8.6years. The corneal sub-basal nerve plexus density was markedly reduced in patients with Parkinson’s disease (7.56±2.4mm/mm2) compared with controls (15.91±2.6mm/mm2) (p<0.0001). Corneal sensitivity did not differ significantly between the patients with Parkinson’s disease (0.79±1.2mBAR) and the control group (0.26±0.35mBAR), p=0.12. Sub-basal nerve density was not significantly different between the eye ipsilateral to the side of the body with most-severe motor symptoms, and the contralateral eye. There was a significant positive correlation between ACE-R scores and sub-basal corneal nerve density (R2=0.66, p=0.02). This is the first study to report a significant reduction in corneal sub-basal nerve density in Parkinson’s disease and demonstrate an association with cognitive dysfunction. These results provide further evidence to support the involvement of the peripheral nervous system in Parkinson’s disease, previously thought to be a central nervous system disorder.

Post-photorefractive Keratectomy Pain and Corneal Sub-basal Nerve Density.

Purpose:The perceived and reported pain of patients receiving photorefractive keratectomy (PRK) widely varies. We assessed the potential role of the subbasal nerve plexus density as a predictor of postoperative pain level. Consecutive patients scheduled to undergo PRK at the Refractive Surgery Clinic of Farabi Eye Hospital, Tehran, were approached.Methods:Forty-nine myopic left eyes from 49 patients who consented to undergo scanning slit confocal microscopy assessments preoperatively were included. ImageJ (1.48v) was used to measure the captured subbasal nerve length. Postoperative pain intensity was assessed by the Visual Analog Scale (VAS) (score range: 0 for no pain to 10 for the maximum possible) on the next day of surgery.Results:The mean age of the patients was 27.55 (range: 19–40) years. The median reported pain level was 5. Approximately 32.7% of the subjects reported a pain score of 6 or higher. Mean nerve density was 19.54 (range: 14.34–24.73) mm/mm2. Nerve density was not correlated with the reported intensity of pain (P = 0.172). However, pain was correlated with the reported ocular discomfort, i.e., a pooled index of foreign body sensation, photophobia, burning sensation, and tearing (P < 0.001), and also with the pooled index of ocular inflammatory signs (conjunctival injection and eyelid edema) (P = 0.027).Conclusion:Crude density of corneal nerves may not be a good predictor of post-PRK pain while wearing bandage contact lenses. The predominant pain mechanism appears to be of an inflammatory nature (not nociceptive or neuropathic).