Andrea Cruzat

Corneal sensation and subbasal nerve alterations in patients with herpes simplex keratitis: an in vivo confocal microscopy study.

PURPOSE To study and correlate corneal sensation in patients with herpes simplex keratitis (HSK) with density and morphologic features of subbasal corneal nerves by in vivo confocal microscopy (IVCM). DESIGN Prospective, cross-sectional, controlled, single-center study. PARTICIPANTS Thirty-one eyes with the diagnosis of acute (n = 7) or chronic (n = 24) HSK and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15). METHODS In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmlogie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (> 5.5 cm), mild (> 2.5-5.5 cm), and severe (≤ 2.5 cm) loss of sensation. MAIN OUTCOME MEASURES Changes in corneal nerve density, total nerve number, main nerve trunks, branching, and tortuosity were evaluated after IVCM and were correlated to corneal sensation, disease duration, and number of recurrences. RESULTS Herpes simplex keratitis eyes, as compared with controls, demonstrated significant (P < 0.001) decrease in mean nerve density (448.9 ± 409.3 vs. 2258.4 ± 989.0 μm/frame), total nerve number (5.2 ± 4.5 vs. 13.1 ± 3.8), main nerve trunks (2.3 ± 1.6 vs. 4.7 ± 1.2), and nerve branches (3.2 ± 4.3 vs. 9.8 ± 3.3). In contralateral unaffected eyes, mean nerve density (992.7 ± 465.0 μm/frame), total nerve number (7.8 ± 3.3), and branches (4.5 ± 2.3) were decreased significantly as compared with controls (P < 0.002). Reduced nerve density, total nerve count, and main trunks in HSK eyes were correlated significantly with corneal sensation across all subgroups (P < 0.001). Nerve density decreased within days of infection and was correlated to frequency of episodes in patients with HSK (P < 0.02). CONCLUSIONS In vivo confocal microscopy revealed that the loss of corneal sensation in HSK correlates strongly with profound diminishment of the subbasal nerve plexus after herpes simplex virus infection. Surprisingly, the contralateral, clinically unaffected eyes also demonstrated a diminishment of the subbasal nerve plexus as compared with normal subjects, revealing bilateral nerve alteration in an apparently unilateral disease.

In Vivo Confocal Microscopy of Corneal Nerves: Analysis and Clinical Correlation

Corneal confocal microscopy is a growing technique for the study of the cornea at the cellular level, providing images comparable to ex vivo histochemical methods. In vivo confocal microscopy (IVCM) has an enormous potential, being a noninvasive procedure that images the living cornea, to study both its physiological and pathological states. Corneal nerves are of great interest to clinicians and scientists due to their important roles in regulating corneal sensation, epithelial integrity, proliferation, wound healing, and for their protective functions. IVCM enables the noninvasive examination of corneal nerves, allowing the study of nerve alterations in different ocular diseases, after corneal surgery, and in systemic diseases. To date, the correlation of sub-basal corneal nerves and their function has been studied in normal eyes, keratoconus, dry eye, contact lens wearers, and in neurotrophic keratopathy, among others. Further, the effect of corneal surgery on nerves has been studied, demonstrating the regenerative capacity of corneal nerves and the recovery of sensation. Moreover, IVCM has been applied in the diagnosis of peripheral diabetic neuropathy and the assessment of progression in this systemic disease. The purpose of this review is to describe the principles, applications, and clinical correlation of IVCM in the study of corneal nerves in different ocular and systemic diseases.

Unilateral Herpes Zoster Ophthalmicus Results in Bilateral Corneal Nerve Alteration: An In Vivo Confocal Microscopy Study

PURPOSE Herpes zoster ophthalmicus (HZO), thought to be a unilateral disease, results in loss of corneal sensation, leading to neurotrophic keratopathy. This study aimed to analyze bilateral corneal nerve changes in patients with HZO by in vivo confocal microscopy (IVCM) and their correlation with corneal sensation as a measure of nerve function. DESIGN Prospective, cross-sectional, controlled, single-center study. PARTICIPANTS Twenty-seven eyes with the diagnosis of HZO and their contralateral clinically unaffected eyes were studied and compared with normal controls (n = 15). METHODS In vivo confocal microscopy (Confoscan 4; Nidek Technologies, Gamagori, Japan) and corneal esthesiometry (Cochet-Bonnet; Luneau Ophthalmologie, Chartres, France) of the central cornea were performed bilaterally in all patients and controls. Patients were grouped into normal (>5.5 cm), mild (>2.5-5.5 cm), and severe (<2.5 cm) loss of sensation. MAIN OUTCOME MEASURES Changes in corneal nerve density, total nerve number, main nerve trunks, branching, and tortuosity were evaluated after IVCM and were correlated to corneal sensation, disease duration, and number of recurrences. RESULTS Eyes with herpes zoster ophthalmicus had a significant (P<0.001) decrease in total nerve length (595.8±358.1 vs. 2258.4±989.0 μm/frame), total number of nerves (5.4±2.8 vs. 13.1±3.8), number of main nerve trunks (2.3±1.1 vs. 4.7±1.2), and number of nerve branches (3.2±2.3 vs. 8.4±3.7) as compared with controls. In the contralateral clinically unaffected eyes, total nerve length (1053.1±441.4 μm/frame), total number of nerves (8.3±2.9), and main nerve trunks (3.1±1.0) also were decreased significantly as compared with controls (P<0.01). Reduced nerve density, total nerve count, main trunks, and tortuosity was correlated significantly with corneal sensation across all subgroups (P<0.001). CONCLUSIONS Patients with unilateral HZO demonstrated a profound and significant bilateral loss of the corneal nerve plexus as compared with controls, demonstrating bilateral changes in a clinically unilateral disease. Loss of corneal sensation strongly correlated with subbasal nerve plexus alterations as shown by IVCM. FINANCIAL DISCLOSURE(S) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Autologous Serum Tears for Treatment of Photoallodynia in Patients with Corneal Neuropathy: Efficacy and Evaluation with In Vivo Confocal Microscopy

OBJECTIVE Patients suffering from corneal neuropathy may present with photoallodynia; i.e., increased light sensitivity, frequently with a normal slit-lamp examination. This study aimed to evaluate the efficacy of autologous serum tears (AST) for treatment of severe photoallodynia in corneal neuropathy and to correlate clinical findings with corneal subbasal nerve alterations by in vivo confocal microscopy (IVCM). METHODS Retrospective case control study with 16 patients with neuropathy-induced severe photoallodynia compared to 16 normal controls. Symptom severity, clinical examination and bilateral corneal IVCM scans were recorded. RESULTS All patients suffered from extreme photoallodynia (8.8±1.1) with no concurrent ocular surface disease. Subbasal nerves were significantly decreased at baseline in patients compared to controls; total nerve length (9208±1264 vs 24714±1056 μm/mm(2); P<.0001) and total nerve number (9.6±1.4 vs 28.6±2.0; P<.0001), respectively. Morphologically, significantly increased reflectivity (2.9±0.2 vs 1.8±0.1; P<.0001), beading (in 93.7%), and neuromas (in 62.5%) were seen. AST (3.6±2.1 months) resulted in significantly decreased symptom severity (1.6±1.7; P=.02). IVCM demonstrated significantly improved nerve parameters (P<.005), total nerve length (15451±1595 μm/mm(2)), number (13.9±2.1), and reflectivity (1.9±0.1). Beading and neuromas were seen in only 56.2% and 7.6% of patients. CONCLUSION Patients with corneal neuropathy-induced photoallodynia show profound alterations in corneal nerves. AST restores nerve topography through nerve regeneration, and this correlated with improvement in patient-reported photoallodynia. The data support the notion that corneal nerve damage results in alterations in afferent trigeminal pathways to produce photoallodynia.

Cellular and subbasal nerve alterations in early stage Fuchs’ endothelial corneal dystrophy: an in vivo confocal microscopy study

PurposeTo analyze the morphology and density of corneal epithelial cells, keratocytes, and subbasal nerves, in patients with early stage Fuchs’ endothelial corneal dystrophy (FECD) by in vivo confocal microscopy (IVCM).MethodsIVCM (Confoscan 4, Nidek, Inc.) of the central cornea was performed in 30 corneas of 30 patients with early stage FECD and 13 corneas of 13 normal controls. Images were analyzed for morphology and density of the superficial and basal epithelial cells, keratocyte density, endothelial cell density (ECD), as well as subbasal corneal nerve parameters. Central corneal thickness (CCT) was measured in all patients and normals by ultrasound pachymetry.ResultsThe ECD was significantly lower (−45.5%, P<0.001) in FECD patients as compared with controls. Total number of nerves and main nerve trunks were significantly reduced (−46.3%, P<0.001; −39.7%, P<0.001) in patients with FECD. Posterior keratocyte density was significantly higher in FECD patients (P<0.001). Significant inverse correlations were found between CCT and total number of nerves (r=−0.69, P<0.001), CCT and main nerve trunks (−0.47, P=0.016), as well as CCT and total nerve length (r=−0.62, P=0.006). Significant correlation was found between ECD and total number of nerves (r=0.44, P=0.012) as well as between ECD and main nerve trunks (r=0.65, P<0.001).ConclusionsIVCM demonstrates alterations in corneal innervation in patients with early stage FECD, suggesting a potential role of corneal nerves in the pathogenesis of FECD. Additional studies are required to investigate whether subbasal nerve alterations are caused by nonspecific corneal edema, from FECD-induced decrease in ECD, or potentially leading to loss of endothelial cells.

Current State of In Vivo Confocal Microscopy in Management of Microbial Keratitis

Purpose: The purpose of this study was to review the current literature on in vivo confocal microscopy of the cornea and to discuss the current clinical indications for its use in microbial keratitis. Methods: Review of select recent literature on in vivo confocal microscopy and atypical microbial keratitis. Results: Delayed diagnosis of Acanthamoeba and fungal keratitis is typical, resulting in significant vision loss. This is partially due to the low sensitivity and time delay of corneal cultures. In the hands of an experienced viewer, the confocal microscope has been found to have a sensitivity of up to 90% in the diagnosis of Acanthamoeba keratitis and close to 80% for fungal keratitis. Conclusion: In vivo confocal microscopy is emerging as a tool for rapid diagnoses in severe infectious keratitis with high sensitivity. In addition, it can be used to monitor treatment response, allowing guidance to clinicians for medical or surgical management.

In Vivo Imaging of Corneal Inflammation: New Tools for Clinical Practice and Research

Purpose: Infectious and inflammatory corneal diseases are a major cause of blindness. To date, assessment of corneal inflammation, has only been possible by slit-lamp biomicroscopy. The purpose of this study is to review the current state of imaging technologies enabling in vivo imaging of inflammation in the cornea. Methods: Literature review of peer-reviewed articles on in vivo imaging modalities. Results: Current means of diagnosis and treatment follow-up for immune and infectious keratitis are limited to slit-lamp biomicroscopy. Several modalities are currently emerging, allowing for in vivo imaging of corneal inflammation, including in vivo confocal microscopy, anterior segment optical coherence tomography, and intravital multiphoton microscopy. Conclusion: Several in vivo imaging technologies are currently evolving, allowing for objective assessment of corneal inflammation and treatment response.

Corneal Epithelial Immune Dendritic Cell Alterations in Subtypes of Dry Eye Disease: A Pilot In Vivo Confocal Microscopic Study.

PURPOSE To evaluate density and morphology of corneal epithelial immune dendritic cells (DCs) in different subtypes of dry eye disease (DED) using in vivo confocal microscopy (IVCM). METHODS This retrospective study included 59 eyes of 37 patients with DED and 40 eyes of 20 age-matched healthy controls. Based on clinical tests, eyes with DED were categorized into two subtypes: aqueous-deficient (n = 35) and evaporative (n = 24). For all subjects, images of laser scanning in vivo confocal microscopy (IVCM) of the central cornea were analyzed for DC density and DC morphology (DC size, number of dendrites, and DC field). These DC parameters were compared among all dry eye and control groups. RESULTS Compared with the controls, patients with DED had significantly higher DC density, larger DC size, higher number of dendrites, and larger DC field (all P < 0.001). Comparison between aqueous-deficient and evaporative subtypes demonstrated that DC density was significantly higher in aqueous-deficient subtype (189.8 ± 36.9 vs. 58.9 ± 9.4 cells/mm2, P = 0.001). However, there were no significant differences in morphologic parameters between DED subtypes. When aqueous-deficient DED with underlying systemic immune disease (Sjögrens syndrome and graft versus host disease) were compared with nonimmune conditions, the immunologic subgroup showed significantly higher DC density, DC size, and number of dendrites (all P < 0.05). CONCLUSIONS Corneal IVCM demonstrated differential changes in DC density and morphologic DC parameters between subtypes of DED. These changes, which reflect the degree of immune activation and inflammation in DED, can be used for clinical practice and endpoints in clinical trials.

Correlation between human tear cytokine levels and cellular corneal changes in patients with bacterial keratitis by in vivo confocal microscopy.

PURPOSE We investigated bilateral tear cytokine levels in patients with unilateral bacterial keratitis (BK) as associated with in vivo confocal microscopic (IVCM) alterations in corneal nerves and dendritiform immune cells (DCs). METHODS A total of 54 (13 BK, 13 contralateral, 28 healthy controls) tear samples was collected prospectively and analyzed by multiplex microbeads assay. The IVCM of the central cornea was performed on the same day, and assessed for corneal nerve and DC alterations. RESULTS Interleukin-1β, IL-6, and IL-8 were significantly elevated only in affected eyes (66.6 ± 26.8, 7174 ± 2430, and 810 ± 315 ρg/mL, respectively; P = 0.04, P < 0.001, and P < 0.001, respectively), compared to healthy controls (13.0 ± 4.0, 171.8 ± 32.1, and 56.5 ± 33.8 ρg/mL). Levels of chemokine ligand 2 (CCL-2), IL-10, and IL-17a were elevated only in contralateral eyes (813 ± 478, 86.7 ± 38.3, and 3350 ± 881 ρg/mL, respectively; P = 0.02, P = 0.01, and P = 0.04, respectively), compared to controls (73.7 ± 25.3, 17.5 ± 4.9, and 1350 ± 337 ρg/mL). Triggering receptor expressed on myeloid cells (TREM)-1 was significantly elevated in affected (551 ± 231 ρg/mL, P = 0.02) and contralateral unaffected (545 ± 298 ρg/mL, P = 0.03) eyes compared to controls (31.3 ± 12.4 ρg/mL). The density of DCs was significantly increased in affected (226.9 ± 37.3 cells/mm(2), P < 0.001) and unaffected (122.3 ± 23.7 cells/mm(2), P < 0.001) eyes compared to controls (22.7 ± 5.9 cells/mm(2)). Sub-basal nerve density significantly decreased in affected (3337 ± 1615 μm/mm(2), P < 0.001) and contralateral (13,230 ± 1635 μm/mm(2), P < 0.001) eyes compared to controls (21,200 ± 545 μm/mm(2)). Levels of IL-1β, IL-6, and IL-8 were significantly correlated with DC density (R = 0.40, R = 0.55, and R = 0.31, all P < 0.02) and nerve density (R = -0.30, R = -0.53, and R = -0.39, all P < 0.01). CONCLUSIONS Proinflammatory tear cytokines are elevated bilaterally in patients with unilateral BK, and are correlated strongly with alterations in DCs and nerve density as detected by IVCM.

Wound anatomy after type 1 Boston KPro using oversized back plates.

Purpose: To compare the anatomy of the graft–host junction and anterior chamber angle after Boston Keratoprosthesis (KPro) placement using oversized (9.5-mm) and standard (8.5-mm) back plates. Methods: Six patients with 9.5-mm titanium back plates and 10 patients with 8.5-mm titanium back plates were imaged by anterior segment optical coherence tomography 6 to 12 months after KPro placement. The location of the graft–host junction in relation to the back plate, the corneal thickness at the graft–host junction, and the anterior chamber angle were assessed. The clinical outcomes and incidence of retroprosthetic membrane (RPM) formation in this cohort were retrospectively evaluated. Results: The oversized back plates completely covered the graft–host junction in all quadrants, allowing the complete apposition of the posterior surface of the carrier graft with the host cornea, with decreased graft–host junction wound thickness. The standard back plates covered the posterior aspect of the carrier graft but not the graft–host junction or the host cornea, resulting in a significantly thicker graft–host junction. None of the patients with larger back plates developed a significant RPM during a 12-month follow-up period. One patient with a larger back plate developed a corneal melt at the KPro stem as a result of chronic exposure. Conclusions: Oversized KPro back plates effectively cover the graft–host junction without any adverse effects on angle anatomy or wound healing. This may be a strategy to provide better wound apposition, reduce RPM formation, and reduce angle closure from iris synechiae to the wound.