Corneal sensation after topical anesthesia.

Background: The purpose of this study was to quantify the inter-eye difference in corneal sensations in patients with infectious corneal ulcers using the Cochet-Bonnet esthesiometer (CBE). Material and methods: Patients with unilateral corneal ulcers of at least 1.5 mm of the clear cornea in all quadrants meeting the study criteria were identified and enrolled. The clinical features with their etiologies were noted. The corneal sensations were measured with CBE in all four quadrants. Patients were further sub-categorized based on the surface area and the “time to heal” of the ulcers for further correlation and analysis. Results: This was a cross-sectional study conducted at a tertiary care center. The study included 35 patients, with the majority (30 patients, 85.7%) diagnosed with fungal etiology. The average corneal sensations in the ulcer and the normal eyes were 52.29 mm and 57.36 mm, respectively. The inter-eye differences were 3.93 mm (p = 0.06) and 6.55 mm (p = 0.04) among patients with an average surface area of ≤ 10 mm 2 and > 10 mm 2 , respectively. Patients who took up to 30 days and > 30 days to heal had inter-eye differences in a sensation of 0.71 mm (p = 0.04) and 6.14 mm (p = 0.05), respectively. Conclusions: The mean corneal sensations in all quadrants were less significant in the infectious ulcer eyes than normal eyes. Infectious ulcers with a surface area of > 10 mm2 had greater inter-eye differences in their corneal sensitivities. Patients who took a longer "time to heal" of > 30 days showed a significant and greater inter-eye difference in their corneal sensitivities.

The purpose of this study was to investigate corneal sensation, subbasal nerve plexus (SBNP), and ocular surface symptoms in patients who underwent multiple intravitreal antivascular endothelial growth factor (anti-VEGF) injections for age-related macular degeneration (AMD) and diabetic macular edema (DME). Forty patients with previous anti-VEGF intravitreal injections (20 AMD and 20 DME) and 30 healthy controls were included in this study. In vivo corneal confocal microscopy (IVCM) of the SBNP, corneal sensitivity measurement with a Cochet-Bonnet esthesiometer, noninvasive tear break-up times, and ocular surface disease score index (OSDI) calculation were performed for each participant. Corneal nerve fiber density, corneal nerve branch density, total length of all nerve fibers, corneal total branch density, corneal nerve fiber area, corneal nerve fiber width, and corneal nerve fiber fractal dimension parameters were obtained by automatic digital analysis. Corneal nerve fiber density, corneal nerve branch density, total length of all nerve fibers, and corneal nerve fiber fractal dimension in IVCM imaging and corneal sensitivity were significantly decreased in both AMD and DME groups compared with the control group. Corneal nerve fiber width and OSDI scores were significantly increased in AMD and DME groups compared with the control group. None of the IVCM parameters were significantly different between AMD and DME groups. Corneal sensitivity was decreased in patients with DME compared with patients with AMD. Tear break-up time was not different among the groups. Corneal SBNP parameters were affected, corneal sensitivity was decreased, and OSDI scores were increased in patients with multiple intravitreal anti-VEGF injections. IVCM parameters were not significantly different between AMD and DME groups.

Decreased Corneal Sensation and Subbasal Nerve Density, and Thinned Corneal Epithelium as a Result of 360-Degree Laser Retinopexy

PurposeTo describe the clinical characteristics of patients suffering from chronic dry eye (DE) and pain after refractive surgery (RS). MethodsCross-sectional, observational, single-visit study. DE-, pain- and psychological-related symptoms were evaluated with specific questionnaires. DE-related tests evaluated tear osmolarity, conjunctival hyperemia, Meibomian gland dysfunction, tear stability and production, and ocular surface staining. Corneal mechanical sensitivity (Cochet-Bonnet) was measured pre/post topical anesthesia, and symptomatic variation post-anesthesia (anesthetic challenge test) was recorded. When pain was present, it was further categorized as neuropathic or nociceptive based on published criteria. ResultsWe recruited 104 patients (39.5 ± 9.5 years). Most, 85.6%, had corneal RS as opposed to intraocular RS. Migraines, anxiety, depression (p < 0.0001), and central sensitization syndromes (p = 0.0214) were more frequent post-RS than pre-RS. Persistent DE-symptoms, severe in 86.5% patients, developed in a range of 0–204 months post-RS. Dryness and pain were the two most frequent symptoms. The only DE-related tests showing abnormal values were tear osmolarity (315.2 ± 17.1 mOsm/L; normal ≤308) and tear break-up time (4.1 ± 2.5 s; normal >7). Corneal sensitivity was 55.4 ± 7.0 mm, and decreased (p < 0.0001) after topical anesthesia, 6.0 ± 10.4 mm. However, it remained pathologically elevated, ≥10 mm in 61 (58.7%) patients. The normal symptomatic post-anesthesia improvement was absent in 58 (55.7%) patients. Ocular pain was present in 82 (78.8%) patients, and it was categorized as neuropathic in 66 (80.5%) of them, 63.5% of the entire cohort. ConclusionsChronic ocular pain and its neuropathic subtype were diagnosed in 78.8% and 63.5% respectively of patients seeking consultation for persistent symptomatic DE post-RS.

To determine the effect of feline congenital glaucoma (FCG) on corneal sensitivity, and relationships between corneal sensitivity, central corneal thickness (CT), and corneal diameter (CD). Corneal sensitivity (estimated by corneal touch threshold [CTT] using Cochet-Bonnet esthesiometry); CT using ultrasonic pachymetry; intraocular pressure (IOP) using rebound tonometry; and maximal horizontal CD were measured in 16 normal and 14 FCG cats, both males and females, aged 7months-3.5years. All procedures complied with an Institutional Animal Care and Use Committee-approved protocol. Data were analyzed by linear regression: paired Student's t tests for between-eye comparisons, and unpaired Student's t tests for comparisons between groups. Relationships between parameters were evaluated by Pearson correlation coefficients and linear mixed effects modeling. For statistical tests, with the exception of values that were Benjamini-Hochberg adjusted for multiple comparisons, P-values < 0.05 were considered significant. Mean CTT and CT values were lower in FCG eyes relative to normal eyes, but differences were not statistically significant. Mean CD was significantly larger in FCG eyes relative to normal eyes, and there was a significant negative correlation between CD and CTT in FCG (r=-0.8564, corrected P=0.005). These associations were confirmed in linear mixed effects models. Eyes with FCG have significantly larger CDs when compared with normal eyes, and larger CDs correlated with decreased corneal sensitivity in this group. Further studies are warranted to explore the effect of buphthalmos and corneal enlargement on corneal sensitivity and innervation in feline subjects with chronic glaucoma.

IL-6 Contributes to Corneal Nerve Degeneration after Herpes Simplex Virus Type I Infection

There are several topical anaesthetics available to the optometrist as a preservative‐free unit dose formulation. There is little comparative data as to the efficacy and tolerability of these drugs. The aim of this study was to compare the depth and duration of corneal anaesthesia following instillation of one drop of 0.4% benoxinate, 0.5% amethocaine and 0.5% proxymetacaine. The tolerability of each anaesthetic was assessed using a linear 10‐point arbitrary comfort scale. Fourteen male subjects participated in the study (mean age 26.6 + 5.0 years). Corneal sensitivity was measured using a slit‐lamp mounted Cochet‐Bonnet aesthesiometer prior to installation, and at 1, 3, 5, 10, 15, 20, and 30 min after, and continued if necessary until corneal sensitivity had returned to pre‐instillation levels. For each anaesthetic complete anaesthesia occurred within 1 min of instillation and a return to baseline sensitivity levels occurred by 30 min. No significant difference in anaesthesia was found between drugs at each time point. In contrast tolerability profiles indicated that proxymetacaine was significantly better tolerated than either amethocaine (P &lt; 0.01) or benoxinate (P &lt; 0.001). This together with an excellent safety record makes proxymetacaine an ideal choice for optometric procedures requiring short‐acting corneal anaesthesia.

OBJETIVOS: Comparar a sensibilidade tatil corneal entre olhos normais e aqueles com phthisis bulbi e avaliar as alteracoes provocadas na sensibilidade tatil corneal pelo uso de lente escleral cosmetica em phthisis bulbi. METODOS: Estudo prospectivo de 23 pacientes com phthisis bulbi unilateral. Foram realizadas medidas da sensibilidade tatil corneal em ambos os olhos utilizando-se o estesiometro de Cochet-Bonnet antes e apos 3 meses do uso da lente escleral cosmetica. RESULTADOS: Em todos os pacientes, a medida da sensibilidade tatil corneal no olho com phthisis bulbi foi menor do que no contralateral (controle). Em 96% houve diminuicao da sensibilidade tatil corneal apos a adaptacao da lente escleral cosmetica. CONCLUSAO: Apos a adaptacao da lente escleral cosmetica, ocorre diminuicao da sensibilidade tatil corneal nos olhos. A fisiopatologia e semelhante a encontrada nos usuarios de lentes de contato.

Effects of upper eyelid blepharoplasty on ocular surface sensation and tear production

Facial nerve palsy (FNP) impacts the ocular and periocular regions. Preganglionic trigeminal nerve palsy (PrGTP) may complicate preganglionic FNP (PrGFP), resulting in neurotrophic keratopathy (NK), risking corneal sequelae. We present a case series where comprehensive eyelid surgery (CES) to manage the eyelid sequelae of PrGFP, complicated by PrGTP, resulted in the recovery of corneal sensation, avoiding corneal neurotisation surgery (CNS). A retrospective case series of three patients with PrGFP and PrGTP in whom eyelid abnormalities were addressed through CES. Outcome measures include markers of trophic function, including ocular surface integrity as determined by fluorescein assessment of cornea staining and corneal sub-basal nerve plexus density (CSND) via in vivo confocal microscopy where available. Corneal scarring was assessed, and corneal sensitivity was determined via Cochet-Bonnet or corneal wisp testing. Three patients with longstanding PrGFP and PrGTP (mean of 28.3 (range 18-49) months) underwent CES to correct the eyelid sequelae of FNP. On presentation, two out of three cases had a complete absence of corneal sensation, while one out of three had reduced sensation. All cases had absent trophic nerve function. Following CES, trophic function and corneal sensation started to improve on average 19 days and 10 months later, respectively, for the three patients. CSPD had nearly doubled at 6 months postoperatively in the patient who had this assessed. In cases of NK due to PrGTP complicated by PrGFP, CES should be attempted before considering CNS since improvement in corneal sensation and trophic function may occur. CES helps to reduce exposure and may improve corneal sensation regardless of aetiology.

ABSTRACTObjectiveTo evaluate the evolution of corneal sensitivity in healthy beagle puppies during the first weeks of life, compare these results with adult corneal sensitivity, and determine the age at which adult corneal sensitivity levels are reached.Animals StudiedTwelve puppies and five adult females.ProceduresCorneal sensitivity was assessed in puppies weekly from 2 to 7 weeks of age and in their mothers by measuring the corneal touch threshold (CTT) in the central cornea using a Cochet–Bonnet esthesiometer. Hygrometric and temperature measurements were recorded throughout the study period.ResultsIn puppies, esthesiometry indicated a progressive decrease in corneal sensitivity with age. Sensitivity was higher between 2 and 4 weeks, which stabilized between 5 and 7 weeks, with a median CTT values of 0.5, 0.5, 0.8, 1.4, 1.2, and 1.4 g/mm2 at 2, 3, 4, 5, 6, and 7 weeks, respectively. The median CTT in puppies reached the adult median value (1.4 g/mm2) at 5 weeks. The median CTT at 2 weeks was significantly different from the median CTT at 7 weeks (0.5 vs. 1.4 g/mm2). Humidity and temperature were not significantly associated with corneal sensitivity in adults.ConclusionsIn this study, corneal sensitivity in beagle puppies was higher during the first 3 weeks of life compared to 7 weeks. During this early period, puppies exhibited corneal sensitivity levels exceeding those of adults, which subsequently decreased to adult‐equivalent values between 5 and 7 weeks of age.

To measure the density of cells in different layers of the cornea and to determine whether morphologic changes of the subbasal corneal nerve plexus are present in eyes with the pseudoexfoliation (PEX) syndrome. Twenty-seven patients with unilateral PEX syndrome and 27 normal controls were investigated. All eyes underwent corneal sensitivity measurements with an esthesiometer and in vivo confocal microscopic study. Densities of the epithelial, stromal, and endothelial cells were measured. The density and tortuosity of the subbasal corneal nerve plexus were also evaluated. Eyes with PEX syndrome had significantly lower cell densities in the basal epithelium (P = 0.003), anterior stroma (P = 0.007), intermediate stroma (P = 0.009), posterior stroma (P = 0.012), and endothelium (P < 0.0001) than in the corresponding layers of normal eyes. PEX eyes also had lower subbasal nerve densities and greater tortuosity of the nerves than normal eyes. Fellow eyes of patients with PEX also had significantly lower densities of the basal epithelial and endothelial cells than the normal eyes. Corneal sensitivity was significantly decreased in PEX eyes, and this was significantly correlated with the decrease of basal epithelial cell and subbasal nerve densities. These results have shed light on understanding of the pathogenesis of decreased corneal sensitivity in eyes with PEX syndrome. PEX syndrome is probably a binocular condition for which keratopathy of the fellow eye also requires observation.

Tear production and corneal sensitivity in diabetes

Ocular examinations were completed on a group of 10 Atlantic puffins (Fratercula arctica), 5 males and 5 females that ranged in age from 8 months to older than 30 years. The exams consisted of intraocular pressure/rebound tonometry, tear production/phenol red thread test, central corneal thickness/ultrasound pachymetry, and corneal sensitivity/esthesiometry. On ocular examination, there were no corneal abnormalities observed. Bilateral cataracts were diagnosed in 8 puffins, 6 of which were considered incipient, focal subcapsular opacities. One bird had hypermature cataracts and was removed from the study and excluded from data analysis; the other birds had no evidence of ophthalmic pathology that would interfere with diagnostic results (n = 9). All results for 9 birds were included in the study, with the exception of 1 puffin's tear production, which was too low for accurate assessment and was excluded from data analysis. There were no significant differences between right and left eye measurements for intraocular pressure, corneal thickness, and corneal sensitivity. The median intraocular pressure for both eyes (OU) was 13 mm Hg with an interquartile range [IQR] of 12-15 mm Hg. The median corneal thickness OU was 241 µm, IQR 233-248 µm. The median corneal sensitivity OU was 1.13 cm, IQR 0.81-1.50 cm. There was a significant difference between right and left eye measurements for tear production (right eye median, 7.5 mm/15 s, IQR 6.5-9.3 mm/15 s; and left eye median, 5.0 mm/15 s, IQR 4.0-7.3 mm/15 s) (P= .03), with the right eye producing more tears than the left. However, 1 puffin was determined to be an outlier, and when removed, there was no longer a significant difference (OU median, 7.0 mm/15 s, IQR 4.6-8.0 mm/15 s) (P = .38). There was no significant difference between sex and intraocular pressure, tear production, and corneal sensitivity. However, there was a significant difference between sex and corneal thickness (P = .02), with males (left eye median, 249 µm, IQR 241-249 µm) having thicker corneas than females (left eye median, 236 µm, 234-238 µm). Although sample size precluded statistical testing, there appeared to be an association between opacities and increasing age. There were no associations between age and intraocular pressure, tear production, or corneal thickness. There was a moderate correlation between age and corneal sensitivity, with older birds showing decreased corneal sensitivity (r = -0.57). Although the sample size of 9 birds was small, these findings provide preliminary ranges for ocular parameters of Atlantic puffins.

To determine the corneal sensitivity of healthy, immature, and adult alpacas to establish normal reference values for this species. Six normal crias and 18 normal adult alpacas. Corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) in five regions of the cornea using a Cochet-Bonnet aesthesiometer. The nylon filament length in cm was then converted to applied pressure values in mg/0.0113 mm(2) and g/mm(2) using a conversion chart. The central region of the cornea was the most sensitive, and the dorsal and temporal regions were the least sensitive in alpacas. There were no significant differences between the right and left eyes or between values in males and females at any site. Crias had significantly greater corneal sensitivity compared with adult alpacas in all five regions of the cornea that were evaluated. Normal reference values for CTT in alpacas were established using a Cochet-Bonnet aesthesiometer. The central region of the cornea is the most sensitive in alpacas, and crias have higher corneal sensitivity than adult alpacas.