Changes In Corneal Sensitivity Research Articles

Corneal Neurotization for Neurotrophic Keratopathy: A Multicentre Experience.

Corneal neurotization is an emerging technique that offers potential for visual rehabilitation in neurotrophic keratopathy. This study reports on a multicenter experience and outcomes for both direct and indirect methods of corneal neurotization. Retrospective case series. Sixteen patients with neurotrophic keratopathy who underwent corneal neurotization across 5 centers in Australia and Israel were identified for inclusion. Corneal neurotization was performed via direct neurotization from the ipsilateral or contralateral supraorbital/supratrochlear nerve or by the use of an interpositional sural nerve graft. Change in corneal sensitivity (measured in millimeters by the Cochet-Bonnet aesthesiometer), visual acuity, and corneal health. Over a mean follow-up period of 31.3 months (range: 3 months-8 years), mean corneal sensitivity improved from 3.6 mm (range: 0-25 mm) to 25.3 mm (range: 0-57 mm). Visual acuity improved on average from 20/380 to 20/260. Twelve of 16 patients (75.0%) improved in at least 2 out of the 3 main outcome measures. Nine patients (56.3%) showed an improvement in visual acuity; 13 (81.3%) showed an improvement in average corneal sensitivity; and 11 (68.8%) showed an improvement in corneal health. There were no intraoperative or postoperative complications. Corneal neurotization is an emerging surgical treatment option for the management of neurotrophic keratopathy. With appropriate case selection, outcomes are favorable and complication rates are low, for a condition that is otherwise challenging to manage. Patients with severe neurotrophic keratopathy should be considered for this surgical treatment option.

Corneal nerve changes in herpes zoster ophthalmicus: a prospective longitudinal in vivo confocal microscopy study.

To study the changes in corneal nerves and corneal sensitivity over a 6-month period in patients with herpes zoster ophthalmicus (HZO) compared with healthy subjects. This was a prospective longitudinal study on patients with newly diagnosed HZO. In vivo confocal microscopy (IVCM) corneal nerve parameters and corneal sensitivity were measured and compared between eyes with HZO, contralateral eyes and controls at baseline, 2 and 6 months. Fifteen subjects with HZO and 15 healthy age and sex matched controls were recruited. HZO eyes revealed a reduction in corneal nerve branch density (CNBD) from baseline to 2 months (9.65 ± 5.75 vs. 5.90 ± 6.87/mm2, p = 0.018), and decreased corneal nerve fibre density (CNFD) at 2 months when compared with control (p = 0.025). However, these differences resolved by 6 months. HZO fellow eyes demonstrated increased corneal nerve fibre area (CNFA), corneal nerve fibre width (CNFW) and corneal nerve fractal dimension (CNFrD) at 2 months compared with baseline (p = 0.025, 0.031, 0.009). There was no change in corneal sensitivity for both HZO affected and HZO fellow eyes from baseline or over time, nor was it different from sensitivity in controls. Corneal denervation was present at 2 months in HZO eyes, with an observed recovery by 6 months. HZO fellow eyes demonstrated increased corneal nerve parameters at 2 months, which could represent a proliferative response to nerve degeneration. IVCM is useful in monitoring corneal nerve changes, andis more sensitive in detecting nerve alterations than esthesiometry.

How long does the recovery of corneal sensitivity in different corneal regions take after LASEK?

To determine the corneal sensitivity recovery period after laser-assisted sub-epithelial keratectomy (LASEK) refractive surgery and investigate the effects of ablation depth on it. In this study examinations were performed on 90 right eyes of 90 people (34 males and 56 females) with an age range of 20-35 and an average of 22.26±3.8 years old. A sensation of 5 corneal regions, including the center and 4 mid-peripheral regions, i.e., nasal, inferior, temporal, and superior, each at a distance of 2 mm from the center of the cornea were measured with a Cochet-Bonnet esthesiometer device in 3-time points including before LASEK, 1 and 3mo after the surgery, respectively. LASEK was performed on individuals with stabilized myopia of -1.00 to -7.00 diopters and astigmatism of less than 2.00 diopters. Furthermore, the individuals were divided into three groups regarding ablation depth. The highest level of corneal sensitivity before surgery was related to the center of the cornea (59.1±7.76), and the highest level of corneal sensitivity loss was also related to this region. The sensation of all measured corneal regions significantly reduced 1mo postoperatively and returned to their preoperative levels 3mo after surgery (mean of 5 corneal regions in levels of preoperation: 58.2±6.48, 1mo postoperation: 57.3±5.84, 3mo postoperation: 58.2±5.49; P<0.05). A significant relationship was found between ablation depth and corneal sensitivity changes in the center and temporal regions (P<0.05). Corneal sensitivity in myopia and low astigmatism decreases after LASEK and reaches the preoperative level within 3mo. The depth of ablation during surgery affected the recovery of corneal sensitivity.

Bilateral changes in corneal sensitivity after unilateral corneal infections

AbstractOcular infections such as herpes simplex virus (HSV) keratitis result in ocular sensitivity changes. During acute HSV episodes and eventually during postherpetic outbreaks, spontaneous pain and hyperalgesia are experienced, being reduced by treatment with Na+ channel blockers (not only by local anaesthetics but also by gabapentin, lacosamide or amitriptyline). At the same time, patients commonly develop hypoesthesia due to the decrease of sensitivity to mechanical stimulation, whose appearance could be due to the internalization of Na+ channels in trigeminal sensory neurons innervating the infected cornea.When explored using a gas esthesiometer that allows selective mechanical, chemical, heat and cold stimulation, HSV‐infected corneas showed those sensitivity disturbances to be expected when corneal polymodal nociceptor activity is altered. On the contrary, sensitivity to cold stimuli is not modified, which suggest that cold thermosensitive ocular neurons are not infected by the virus. A surprising result is the alteration, in the same sense although to a lesser degree, of the sensitivity of the contralateral eye. This contralateral altered sensitivity could be caused by a subclinical HSV infection of the contralateral side. Another possibility is that to be due to a neuroimmune interaction that ends up affecting the activity of sensory nerves of both eyes, in a similar way to what happens in non‐infectious inflammatory processes affecting only one eye.(PID2020‐115934RB‐I00 from DOI: MCIN/AEI/10.13039/50110001103)

Age-Related Changes in Corneal Sensitivity.

The aim of this prospective cross-sectional cohort study was to clinically test whether corneal sensation decreases with age, based on subject feedback (psychophysical method), and whether it correlates with general pain perception. Subjects were recruited from 2 equally large age groups: group A (18-30 years) and group B (50-70 years; n = 45 per group). The inclusion criteria were healthy eyes, Ocular Surface Disease Index ≤13, and no contact lens wear. Corneal sensitivity threshold (CST) measurements were performed twice during each of the 2 visits, with the aid of the new Swiss liquid jet esthesiometer for corneal sensitivity (SLACS) and Cochet-Bonnet (CB) esthesiometer. A general pain sensitivity score was obtained from all participants. Ninety subjects completed the study (n = 45 per age group, average age in group A: 24.2 ± 2.94 years, group B: 58.5 ± 5.71 years). Statistically higher CSTs for age group B were only observed for SLACS (mean difference: 1.58 dB, P < 0.001). No correlation was observed between the pain score and the CSTs obtained with either esthesiometry method (r = 0.11, P = 0.25 for liquid jet and r=-0.076, P = 0.61 CB). A statistically significant decrease in corneal sensitivity was observed for the older age group with SLACS in this study, with CB however only a trend in the same direction was noted. General pain perception was not found to correlate with ocular surface sensation.

Corneal Nerve Changes Observed by In Vivo Confocal Microscopy in Patients Receiving Oxaliplatin for Colorectal Cancer: The COCO Study.

An objective method of early identification of people at risk of chemotherapy-induced peripheral neuropathy is needed to minimize long-term toxicity and maximize dose intensity. The aims of the study were to observe corneal nerve microstructure and corneal sensitivity changes and peripheral neuropathy in patients receiving oxaliplatin, and to determine its association with corneal parameters at different stages of treatment and assess utility as non-invasive markers to detect and monitor peripheral neuropathy. Twenty-three patients scheduled to receive oxaliplatin chemotherapy with intravenous 5-FU for gastro-intestinal cancer were recruited and followed up with for 12 months. Ocular examinations including corneal and retinal evaluations, alongside peripheral neuropathy assessment, were performed. The corneal nerve density did not show significant change after chemotherapy when measured with a widely used semi-automated program or an automated analysis technique. Macula and optic nerve function did not change during or after oxaliplatin chemotherapy. However, the corneal nerve density modestly correlated with clinical peripheral neuropathy after 20 weeks of chemotherapy (r = 0.61, p = 0.01) when peripheral neuropathy is typical most profound, and corneal nerve sensitivity correlated with neuropathy at 12 (r = 0.55, p = 0.01) and 20 weeks (r = 0.64, p = 0.006). In conclusion, corneal changes detected on confocal microscopy show moderate association with peripheral neuropathy, indicating their potential to identify the development of oxaliplatin-induced peripheral neuropathy. However, further studies are required to confirm these findings.

Effect of Proparacaine Hydrochloride Eye Drops on the Ocular Surface

<i>Background: </i>Proparacaine hydrochloride (PH), as a a local anesthetic, is used regularly in ophthalmic surgery and optometry. However, few pieces of research on the ocular surface toxicity<i> </i>of PH eye drops have so far been reported. <i>Purpuse: </i>To evaluate the effect of PH on the ocular surface of mice.<i> Methods: </i>Male C57/BL6 mice were divided into four groups: normal, vehicle-treated, 0.05% PH-treated and 0.5% PH treated 7 days. The clinical indications were tear production, corneal sensitivity, and fluorescein staining. The structure and morphology of the cornea were examined by confocal microscopy; the thickness of the corneal center was examined by anterior segment optical coherence tomography (AS-OCT); and the corneal epithelial microvilli morphology was examined using scanning electron microscopy. Hematoxylin-eosin staining was used to characterize the central corneal morphology. Immunofluorescence staining for cytokeratin 10 (K10) was employed to evaluate squamous metaplasia in the corneal epithelium. <i>Results: </i>The results show that topical PH treatment diminished tear production and corneal sensitivity, and increased corneal fluorescein staining scores. Moreover, PH altered the corneal epithelial microvilli morphology, disrupted the epithelial barrier of the cornea, and promoted apoptosis of ocular surface cells. Furthermore, the expression of K10 in the corneal epithelium was found to be increased. <i>Conclusion: </i>Treatment with 0.5% PH caused instability of the tear film, and changes in corneal sensitivity and ocular surface homeostasis.

Dynamic correlation between corneal sensitivity and subjective symptoms in patients with Chronic corneal ulcers

Purpose: This study assessed the correlation between corneal sensitivity and subjective symptoms in patients with chronic corneal ulcers before and after treatment. Methods: Corneal sensitivity was measured with Cochet-Bonnet aesthesiometry in twenty patients with mean age of53 years SD±20.65. Impression cytology was used to assess conjunctivalization, inflammation and keratinization. The epithelial integrity and stromal reaction were determined by anterior segment OCT. Treatment included either conservative measures or surgical ocular surface reconstruction. A questionnaire on subjective symptoms was implemented in order to obtain comparable data about their severity and effect on everyday life. Results: Mean corneal aesthesiometry was 143.03±81.68 mm/grms before treatment and 72.48±72.80 mm/grms on follow-up (p=0.001). An inverse correlation between age and corneal sensitivity was observed before treatment (p=0.002), but not after (p=0.102). Anterior segment OCT on follow-up demonstrated epithelialized corneal surface, reduced stromal reaction and scar tissue preventing further melting. All tested subjective symptoms demonstrated significant change after treatment except driving. Spearman’s analysis demonstrated a correlation between corneal sensitivity and pain (p=0.033), hyperemia (p=0.009) and driving (p=0.043). The change in corneal sensitivity correlated with tearing reduction (p=0.046) and prolonged tolerance to phone use (p=0.044). Conclusions: Cochet-Bonnet aesthesiometry is a useful diagnostic tool for evaluating corneal nerve function and monitoring the effect of treatment.

Corneal Reinnervation and Sensitivity Recovery after Pterygium Excision.

Purpose To evaluate changes in corneal sensitivity and subbasal nerve density after pterygium excision. Methods This prospective trial included 22 eyes with nasal primary pterygium and 18 controls. Corneal sensitivity was evaluated using a Cochet–Bonnet esthesiometer in the nasal, superior, temporal, inferior, and center quadrants of the cornea before surgery and 10 days, 1 month, and 3months after surgery. The central cornea was analyzed using in vivo confocal microscopy (IVCM) before surgery and 1 and 3 months after surgery. Subbasal nerve density and other nerve parameters were analyzed using NeuronJ. Nerve tortuosity was evaluated and graded in individual IVCM scans. The tear film break-up time (TBUT) test and Schirmer's test were performed before surgery, as well as 1 and 3 months after surgery. All the same tests were performed in the controls. Results All affected eyes showed a significant increase in corneal sensitivity in the nasal corneal quadrant after surgery when compared with preoperative data (F = 37.3; P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (F = 37.3; P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (F = 37.3; P < 0.01). Compared with controls, pterygium patients demonstrated decreased corneal subbasal nerve density (Conclusion Pterygium patients demonstrated deteriorated corneal subbasal nerve fibers when compared with healthy controls in terms of nerve length, nerve trunks, and nerve branches. Therefore, pterygium excision improves corneal sensitivity and increases corneal subbasal nerve density.

Short-Term Effects of Overnight Orthokeratology on Corneal Sensitivity in Chinese Children and Adolescents.

Purpose To assess the effects of the 3-month period of orthokeratology (OK) treatment on corneal sensitivity in Chinese children and adolescents. Methods Thirty subjects wore overnight OK lenses in both eyes for 3 months and were assessed at baseline, 1 day, 1 week, 1 month, and 3 months after the treatment. Changes in corneal sensitivity were measured by the Cochet–Bonnet (COBO) esthesiometer at the corneal apex and approximately 2 mm from the temporal limbus. Changes in refraction and corneal topography were also measured. Results Central corneal sensitivity suffered a significant reduction within the first month of the OK treatment period but returned to the baseline level at three months (F = 3.009, P=0.039), while no statistically significant difference occurred in temporal sensitivity (F = 2.462, P=0.074). The baseline of central corneal sensitivity correlated with age (r = −0.369, P=0.045). A marked change in refraction (uncorrected visual acuity, P < 0.001; spherical equivalent, P < 0.001) and corneal topographical condition (mean keratometry reading, P < 0.001; eccentricity value, P < 0.001; Surface Regularity Index, P < 0.001) occurred, but none of these measurements were correlated with corneal sensitivity. Conclusions A 3-month period OK treatment causes a reduction in central corneal sensitivity in Chinese children and adolescents but with a final recovery to the baseline level, which might be because neuronal adaptation occurred earlier in children and adolescents than in adults.

Corneal sensitivity and subjective complaints of ocular pain in patients with fibromyalgia.

PurposeFibromyalgia (FM) is a chronic pain disorder associated with pain and hypersensitivity in various parts of the body. The aim of this study was to understand whether changes in corneal sensitivity were associated with the subjective complaints of these patients.Patients and methodsIn this study, we included 36 patients with FM (30 female, 6 male, mean age: 46.7±9.2 years) and 39 healthy control subjects (33 females, 6 males, mean age: 44.3±7.6 years). We performed a detailed ophthalmological examination, measured tear film breakup time (TBUT), and performed Schirmer I test without anesthetic (SIT). Only patients that did not have any eye disease were included in this study. Subjective complaints of the patients were evaluated with ocular surface disease index (OSDI) scores and the corneal sensation was evaluated with Cochet-Bonnet esthesiometer.ResultsThere was no significant difference between the groups for age, sex, and visual acuity. Both SIT (16.1 mm vs 15.3 mm, P=0.36) and TBUT results (17.8 s vs 18.8 s, P=0.40) were similar in FM group and the controls subjects. However, corneal sensations in central (60.0 mm vs 55.0 mm, P=0.03), superior (57.5 mm vs 50.0 mm, P=0.005), and inferior (53.89 mm vs 46.03 mm, P<0.001) regions were significantly increased in FM patients. There was a significant positive correlation between corneal sensation and OSDI scores.ConclusionIn this study, we have demonstrated that the patients with FM have increased corneal sensitivity and have related ocular surface complaints similar to dry eye disease in the absence of it.

Effect of topical application of 2% lidocaine gel on corneal sensitivity of clinically normal equine eyes

ObjectiveTo assess the degree and duration of corneal anaesthesia provided by topical application of a non-ophthalmic 2% lidocaine gel in horses. Study designExperimental, ‘blinded’, randomized prospective study. AnimalsTwelve adult horses without relevant ocular abnormalities. MethodsBaseline corneal touch threshold (CTT) measurements were obtained bilaterally by use of a Cochet–Bonnet aesthesiometer just prior to topical treatment. A volume of 0.2mL of 2% lidocaine gel was administered in one randomly selected eye and the same volume of a viscous lubricant in the other eye to serve as control. The CTT value was measured on both eyes 5, 10, 20, 30, 45, 60, 75 and 90 minutes after drug application. The potential for local adverse effects following lidocaine gel application was also evaluated. ResultsMean CTT baseline measurements were not significantly different (p>0.05) between the control eyes (3.41±0.56cm) and those subsequently treated with the lidocaine gel (3.50±0.64cm). In control eyes, no significant changes in corneal sensitivity (p>0.05) occurred over time during the study period. By contrast, a marked reduction in corneal sensitivity was observed after lidocaine application, with mean CTT values significantly lower (p<0.001) than those of the control eyes from 5 to 75 minutes. A steady-state maximal corneal anaesthesia was present from 10 to 45 minutes after lidocaine gel application with mean CTT values ranging from 0.21 to 0.45cm. Corneal epithelial irregularities were detected in three lidocaine-treated eyes, but spontaneous resolution occurred within 24hours. Conclusions and clinical relevanceDeep and sustained corneal anaesthesia is achieved after application of 2% lidocaine gel to the equine eye, with minimal changes in the corneal epithelium. It might be useful for minor ophthalmic surgeries performed in the standing sedated horse.

Reduced Corneal Sensitivity and Sub-Basal Nerve Density in Long-Term Orthokeratology Lens Wear.

To investigate changes in corneal sensitivity and nerve morphology in orthokeratology (OK) contact lens wear. In a cross-sectional study, 54 subjects (aged 18-45 years) were grouped into three categories: nonlens (NL), soft lens (SCL), and OK lens wearers. Corneal sensitivity was measured at the corneal apex and 2.5 mm temporal to the apex using the Cochet-Bonnet aesthesiometer. Corneal nerve morphology was assessed by sampling a 1 mm area of the corneal sub-basal nerve plexus using the Heidelberg Retinal Tomograph with Rostock Corneal Module at the corneal apex and 2.5 mm temporal to the apex. Nerve fiber density (NFD) was calculated by measuring the total length of nerve fibers per square millimeter using Image-Pro Analyser. Comparisons between groups were made using mixed analysis of variance and post hoc paired t tests with Bonferroni correction or the Kruskal-Wallis test and post hoc Mann-Whitney U tests as appropriate. There was a significant difference in corneal sensitivity between the three groups (P=0.027). Central threshold was significantly higher in the OK than NL group (0.69±0.42 g/mm vs. 0.45±0.12 g/mm; P=0.048). Mid-peripheral threshold was not different between the three groups (P>0.05). There was a significant difference in NFD between the three groups (P<0.001). Central NFD was significantly less in the OK than NL and SCL groups (OK: 17.89±4.42 mm/mm, NL: 25.87±5.00 mm/mm; SCL: 24.52±4.93 mm/mm; P<0.001). Mid-peripheral NFD was not different between the three groups (P>0.05). Long-term OK lens wear is associated with a decrease in central corneal sensitivity and NFD. The mechanism underlying refractive change during OK treatment seems to impact both corneal sensitivity and nerve morphology.

Changes in corneal subbasal nerve morphology and sensitivity during orthokeratology: Recovery of change

PurposeTo investigate the recovery of orthokeratology (OK)-induced changes in corneal nerve morphology and sensitivity following lens wear discontinuation, over a 3-month period. MethodsSixteen myopic subjects who wore OK lenses during sleep for 3 months discontinued lens wear for 3 months. Corneal nerve morphology and sensitivity were assessed on the right eye only 3 h after waking at the pre-lens wear baseline and after lens wear discontinuation. Corneal nerve fiber density (NFD) and global nerve fiber orientation (GNFO) were assessed by sampling a 1 mm2 area of the subbasal nerve plexus at the corneal apex and temporal mid-periphery using in vivo confocal microscopy. Corneal sensitivity was measured using the Cochet-Bonnet aesthesiometer at similar corneal locations. ResultsSignificant changes in corneal sensitivity, NFD, and GNFO were observed at various corneal locations during the lens wear discontinuation period. In the central cornea, NFD and corneal sensitivity increased during the 3-month non-lens wear period (p < 0.01); no significant changes in NFD or corneal sensitivity were noted in the mid-peripheral cornea. Central corneal sensitivity recovered to pre-lens wear levels after 1 month of non-lens wear. Central NFD appeared to remain slightly decreased after 3 months of non-lens wear compared to pre-lens wear levels, but this difference did not reach statistical significance (p = 0.09). GNFO did not change significantly at the central cornea during the 3-month non-lens wear period, but altered in a counter-clockwise rotational direction (reversal of OK-induced change) at the mid-peripheral cornea (p < 0.05), although it did not appear to fully recover to pre-lens wear orientation (p = 0.05). ConclusionsOK lens-induced reduction in corneal sensitivity recovers with cessation of lens wear, returning to pre-lens wear levels shortly after lens wear discontinuation. Changes to nerve morphology induced by OK lens wear, however, appear to recover more slowly towards pre-lens wear levels. This requires confirmation in a longer non-lens wear period.

Changes in Corneal Subbasal Nerve Morphology and Sensitivity During Orthokeratology: Onset of Change

PurposeTo investigate changes in corneal subbasal nerve fiber density and orientation during a 3-month orthokeratology (OK) lens wear period and their relationship with concurrent changes in corneal sensitivity. MethodsSixteen subjects wore overnight OK lenses for 90 days and were assessed at baseline, Day 30, and Day 90. Nerve images at the corneal apex and temporal mid-periphery were captured from the right eye only using in vivo confocal microscopy and analyzed to calculate nerve fiber density (NFD) and global nerve fiber orientation (GNFO). Corneal sensitivity was measured using the Cochet-Bonnet aesthesiometer at similar corneal locations. Control groups of non-lens (NL) wearing and conventional rigid gas-permeable (GP) lens-wearing subjects were also examined. ResultsSignificant changes in NFD, GNFO and corneal sensitivity were observed during OK lens wear over the study period. In the central cornea, both NFD and corneal sensitivity decreased by Day 30, with further reductions at Day 90. Reduced NFD was associated with reduced corneal sensitivity. In the mid-peripheral cornea only, GNFO was rotated in a clockwise direction at Day 30, with further rotation at Day 90. Corneal sensitivity reduction plateaued by Day 30. In the GP lens-wearing subjects, only corneal sensitivity decreased by Day 30 at both corneal locations. No changes were observed in the NL control subjects. ConclusionsAlterations in corneal nerve morphology occur rapidly with commencement of OK lens wear and appear to underpin functional sensitivity loss. Nerve fiber orientation can provide a useful index for changes in corneal nerve morphology.

Corneal Sensitivity and Inflammatory Biomarkers in Contact Lens Discomfort.

The aim of this study was to analyze whether symptoms of discomfort in hydrogel contact lens (HCL) wearers were associated with changes in corneal sensitivity or levels of tear inflammatory mediators. Sixty-six subjects were included: 47 HCL wearers, further divided into 24 symptomatic and 23 asymptomatic wearers by the Contact Lens Dry Eye Questionnaire short form and 19 non-contact lens wearers. At least 24 h after HCL removal, we obtained scores from the Ocular Surface Disease Index and mechanical, hot, and cold corneal thresholds using a Belmonte esthesiometer. We collected 4 μl of tears with a capillary micropipette and measured levels of 12 inflammatory markers using a bead-based array: epidermal growth factor, fractalkine, interleukin-10 (IL-10), IL-1β, IL-1 receptor antagonist, IL-2, IL-4, IL-6, IL-8, monocyte chemoattractant protein 1, tumor necrosis factor-α, and matrix metalloproteinase 9. There were no significant differences between groups in corneal sensitivity thresholds and levels of tear molecules. The following significant correlations were found in the total sample pooled: Ocular Surface Disease Index correlated with mechanical threshold (p < 0.01; rho = -0.324) and epidermal growth factor (p < 0.01, rho = -0.330), and mechanical threshold correlated with heat threshold (p < 0.01, rho = -0.321). Twenty-four hours after HCL removal, symptoms of discomfort in HCL wearers are not related to changes in corneal sensitivity or tear inflammatory mediator levels. This might indicate either that HCL wear has no effect on these parameters or that ocular surfaces recover from HCL-caused effects during the first hours after HCL removal. However, there were correlations for associations between symptoms, corneal sensitivity, and some molecules in tears.

Recovery of corneal sensitivity after collagen crosslinking with and without epithelial debridement in eyes with keratoconus

To evaluate the changes in corneal sensitivity after corneal collagen crosslinking (CXL) with the epithelium off (epi-off) and with the epithelium on (epi-on) in eyes with keratoconus. Prospective interventional case series. Eye Clinic, A. Fiorini Hospital, Terracina (Latina), Rome, Italy. On the basis of the corneal pachymetry at the area of topographic steepening, eyes treated with CXL were divided in 2 groups: those with a corneal thickness of 400 μm or more (epi-off) and those with a corneal thickness of less than 400 μm (epi-on). Corneal sensitivity was measured using a contact esthesiometer (Cochet-Bonnet) before treatment and 1 and 7 days and 1, 3, 6, 9, and 12 months after treatment. The study evaluated 50 CXL-treated eyes in 50 patients (25 epi-on and 25 epi-off) from January 7, 2012, to December 15, 2012. In the epi-off group, corneal sensitivity was statistically significantly reduced for up to 3 months after CXL and gradually returned to normal levels. In the epi-on group, corneal sensitivity was statistically significantly reduced for up to 7 days but was not statistically significantly different from preoperative values at other measurement times. At 7 days, the corneal sensitivity was statistically significantly lower in the epi-off eyes than in the epi-on eyes. Epi-off and epi-on CXL both caused hypoesthesia, but corneal sensitivity subsequently recovered completely. The corneal hypoesthesia was more pronounced in eyes in which the epi-off technique was used, and the recovery time was shorter for eyes treated using epi-on CXL. No author has a financial or proprietary interest in any material or method mentioned.

Corneal Sensitivity with Contact Lenses of Different Mechanical Properties

To examine the changes in corneal sensitivity after overnight wear of contact lenses with different mechanical properties. Twenty young-adult subjects wore a silicone hydrogel, rigid gas-permeable, or orthokeratology (OK) contact lens in randomized order for a single night of wear in the right eye only. All lenses were matched in Dk/t (∼46 ISO Fatt). Changes in corneal apical radius r(o), asphericity Q, and corneal refractive power (Medmont E300) were measured. Changes in central corneal sensitivity were also measured by a masked investigator using two instruments: Cochet-Bonnet (COBO) aesthesiometer and Non-Contact Corneal Aesthesiometer (NCCA). There were significant differences in corneal topographic change from baseline between the lens types for r(o), Q, and corneal refractive power. There were also significant differences in the change from baseline (mean ± SD) in corneal sensitivity between lens types using the COBO (silicone hydrogel, 0.02 ± 0.17 g/mm(2); rigid gas-permeable, 0.03 ± 0.20 g/mm; OK, 0.22 ± 0.33 g/mm(2)). A significant increase in threshold from baseline was only seen in the OK lenses (p = 0.006). There was no change in sensitivity thresholds from baseline for any lens type using the NCCA (p > 0.05). Central corneal sensitivity is reduced after a single overnight wear of OK lenses, as measured using the COBO aesthesiometer. This suggests that the mechanical force exerted by contact lenses may influence corneal sensitivity.

Impact of Collagen Crosslinking on Corneal Sensitivity in Keratoconus Patients

To evaluate changes in corneal sensitivity after corneal collagen crosslinking in patients having progressive keratoconus. Thirty-six consecutive patients having progressive keratoconus were included in the study. The crosslinking surgery was performed in one eye of each patient (study group) and the opposite eye was used as control (control group). The following steps were done in the procedure: central cornea epithelial debridement, riboflavin solution dropping (1 drop every 5 minutes) for 30 minutes, and subsequently, corneal surface irradiation with Ultraviolet A for 30 minutes, keeping the riboflavin instillation while irradiating. The analysis of corneal tactile sensitivity in each patient was performed using the Cochet-Bonnet aesthesiometer at 5 time points: preoperative and 7, 30, 90, and 180 days after surgery. The study enrolled 72 eyes of 36 patients. Considering the eyes submitted to crosslinking, there was a significant statistical difference concerning the tactile corneal sensitivity at all 5 evaluated moments. The median sensitivity at each time point studied was: preoperative, 52.5 mm (range, 25-60 mm); 7 days, 20.0 mm (range, 5-60 mm); 30 days, 32.5 mm (range, 5-60 mm); 90 days, 40.0 mm (range, 10-60 mm) and 180 days, 45.0 mm (range, 25-60 mm) (P < 0.001). The control group showed no statistical difference among all 5 time points (P = 0.160). Corneal crosslinking performed in keratoconus patients induced a considerable decrease in corneal sensitivity. This decrease was more intense at the first week after the procedure, with a progressive recovery up to 6 months.

Comparison of corneal sensitivity, tear function and corneal staining following laser in situ keratomileusis with two femtosecond laser platforms

PurposeTo evaluate longitudinal changes in corneal sensitivity, tear function, and corneal staining in patients who underwent laser in situ keratomileusis (LASIK) using two different femtosecond lasers.MethodsIn a prospective, randomized clinical trial, contralateral eyes of 45 patients underwent flap creation by either VisuMax or IntraLase™ femtosecond laser. Corneal sensitivity, tear break up time (TBUT), Schirmer’s test, and corneal fluorescein staining were assessed preoperatively and at 1 week, 1 month, and 3 months postoperatively.ResultsThere were no statistical differences in any clinical outcome measure between the two femtosecond lasers (P > 0.05), although there was a trend towards slightly lower reductions for corneal sensitivity and TBUT in VisuMax-operated eyes. Overall, corneal sensitivity was significantly reduced at 1 week (P < 0.05), 1 month (P < 0 .001), and 3 months (P < 0.001) postoperatively. A significantly greater reduction of corneal sensitivity was noted in eyes with a myopic spherical equivalent of −6.00 diopters (D) to −11.25 D as compared with eyes that had a relatively lower level of myopia of less than −6.00 D (P < 0.001). TBUT and Schirmer’s test values were significantly diminished at 1 week postoperatively (P < 0.04). Overall, corneal staining was significantly increased at 1 week postoperatively (P < 0.001). The level of myopia did not significantly affect postoperative changes in TBUT, Schirmer’s test values, or corneal staining (P > 0.05).ConclusionThis study showed that changes in corneal sensitivity, tear function, and corneal staining were statistically similar in LASIK using VisuMax and IntraLase femtosecond lasers for flap creation. However, the trend towards faster recovery of corneal sensitivity and TBUT observed in VisuMax-operated eyes may be attributable to improved technical specifications.