Cochet-Bonnet Aesthesiometer Research Articles

Dry Eye in Graves’ Ophthalmopathy: Correlation with Corneal Hypoesthesia

To evaluate dry eye disease and corneal sensitivity in patients with early and active Graves ophthalmopathy (GO). A total of 52 eyes of 26 patients with early GO and 74 eyes of 37 age- and sex-matched controls were included in our study. Dry eye disease was assessed based on the criteria of the International Dry Eye Workshop. Diagnosis of early GO was based on the European Group on Graves' Orbitopathy consensus statement. Clinical Activity Score (CAS) and Werner-NOSPECS Score were determined. Corneal sensitivity was assessed using a Cochet-Bonnet aesthesiometer. A total of 67.8% of patients with early GO and 13.5% of healthy controls had ocular surface dryness (p<0.001). The mean Schirmer test score was significantly lower in patients with early GO (12.88 ± 7.94 mm [right eyes] and 14.04 ± 9.00 mm [left eyes]) than in controls (18.08 ± 7.26 mm [right eyes] and 18.05 ± 7.50 mm [left eyes] [p<0.05]). The tear film break-up time was lower in patients by 5.46 seconds and 5.74 seconds in right and left eyes (p<0.001). We also found a significant reduction in corneal sensitivity in patients with early GO (4.16 ± 0.68 [right eyes] and 4.10 ± 0.89 [left eyes]) than in controls (4.70 ± 0.34 [right eyes] and 4.72 ± 0.34 [left eyes] [p<0.05]). The CAS correlated significantly with the Schirmer test (r = -0.60, p = 0.003). Dry eye is common in early GO even in the absence of apparent exophthalmos and is associated with CAS and reduced corneal sensitivity.

Comparison of efficacy and duration of effect on corneal sensitivity among anesthetic agents following ocular administration in clinically normal horses

To compare efficacy and duration of effect on corneal sensitivity of 0.5% proparacaine hydrochloride, 0.5% bupivacaine hydrochloride, 2% lidocaine hydrochloride, and 2% mepivacaine hydrochloride solutions following ocular administration in clinically normal horses. 68 clinically normal horses. 60 horses were assigned to receive 1 anesthetic agent in 1 eye. For each of another 8 horses, 1 eye was treated with each of the anesthetic agents in random order with a 1-week washout period between treatments. Corneal sensitivity was assessed via corneal touch threshold (CTT) measurements obtained with a Cochet-Bonnet aesthesiometer before and at 1 minute, at 5-minute intervals from 5 to 60 minutes, and at 10-minute intervals from 60 to 90 minutes after application of 0.2 mL of anesthetic agent. General linear mixed models were fitted to the CTT data from each of the 2 experimental groups to assess the effects of the anesthetic agents over time, accounting for repeated observations within individual horses. Corneal sensitivity decreased immediately following topical application of each anesthetic agent; effects persisted for 35 minutes for proparacaine and mepivacaine treatments, 45 minutes for lidocaine treatment, and 60 minutes for bupivacaine treatment. Maximal CTT reduction was achieved following application of bupivacaine or proparacaine solution, whereas mepivacaine solution was least effective. Ocular application of each evaluated anesthetic agent reduced corneal sensitivity in horses; although 0.5% proparacaine or 2% lidocaine solution appeared to induce adequate short-duration corneal anesthesia, use of 0.5% bupivacaine solution may be more appropriate for procedures requiring longer periods of corneal anesthesia.

Topical 1% Nalbuphine on corneal sensivity and epitheilization after experimental lamellar keratectomy in rabbits

The present study was aimed to evaluate the effects of topical 1% nalbuphine on corneal sensitivity and re-epithelialization, after lamellar keratectomy in rabbits. All protocols were approved by the Animal Care Comission of São Paulo State University (Protocol 028793-08) and were conducted in accordance with the Institutional Animal Committee and the Association for Research in Vision and Ophthalmology (ARVO) statement for the use of animals in research. Surgeries were performed on the left eye (Nalbuphine Group) and on the right eye (Control Group). Two groups were formed (n=10) and corneas received either 30µl of 1% nalbuphine (NG) or 30µl of 0,9% saline (CG). Treatments occurred at 7, 11, 15 and 19 hours. After the surgery, the corneas were stained with fluorescein and photographed daily; corneal touch threshold (CTT) was assessed with Cochet-Bonnet aesthesiometer, at 7 and 19 hours, 20 minutes after treatments. Data were statistically compared with repeated measures ANOVA and Bonferroni post-hoc test, and T test (P&lt;0.05). Average ±SD time for corneal re-epithelialization was 7.40±0.47 days (NG) and 8.90±0.31 days (CG) (P=0.11). The results showed that the diameter of the keratectomized area and CTT did not change significantly between both groups (P&gt;0.05); however, a higher area under the curve for both parameters was observed in the NG (2771), in comparison to CG (2164). Topical 1% nalbuphine did not change significantly corneal sensitivity and re-epithelialization, after experimental lamellar keratectomy in rabbits.

Elevated IGFBP3 Levels in Diabetic Tears: A Negative Regulator of IGF-1 Signaling in the Corneal Epithelium

To determine the ratio of IGFBP3:IGF-1 in normal and diabetic human tears, and in telomerase-immortalized human corneal epithelial cells (hTCEpi) cultured under elevated glucose conditions and to correlate these changes with total and phosphorylated levels of IGF-1R. Tear samples were collected noninvasively from diabetic subjects and non-diabetic controls; corneal sensitivity was assessed using a Cochet-Bonnet Aesthesiometer. Conditioned media were collected following culture of hTCEpi cells in normal (5 mM) and elevated (25 mM) glucose conditions; mannitol was used as an osmotic control. IGFBP3, IGF-1, and phosphorylated IGF-1R levels were assessed by ELISA. IGFBP3 and IGF-1R mRNA were assessed by real-time polymerase chain reaction (PCR). Total and phosphorylated IGF-1R expression in whole cell lysates was assessed by western blot. There was a 2.8-fold increase in IGFBP3 in diabetic tears compared to non-diabetic controls (P=0.006); IGF-1 levels were not significantly altered. No difference in corneal sensitivity was detected between groups. The concentration of IGFBP3 in tears was independent of IGF-1. Consistent with human tear measurements in vivo, IGFBP3 secretion was increased 2.2 fold (P<0.001) following culture of hTCEpi cells under elevated glucose conditions in vitro. Treatment with glucose and the mannitol control reduced IGFBP3 mRNA (P<0.001). Total IGF-1R levels were unchanged. The increase in the IGFBP3:IGF-1 ratio detected in diabetic tears compared to normal controls blocked phosphorylation of the IGF-1R by IGF-1 (P<0.001) when tested in vitro. Taken together, these in vivo and confirmatory in vitro findings suggest that the observed increase in IGFBP3 found in human tears may attenuate IGF-1R signaling in the diabetic cornea. A long-term increase in IGFBP3 may contribute to epithelial compromise and the pathogenesis of ocular surface complications reported in diabetes.

Reversal of Sensation of Conjunctival Autograft after Pterygium Surgery

To evaluate sensation change at nasal and superior conjunctival and corneal quadrants after pterygium surgery with conjunctival autograft. A prospective study was carried out in 14 patients. Seventeen eyes were operated for primary nasal pterygium. Sensation in nasal and superior conjunctival and corneal quadrants was measured with a Cochet-Bonnet aesthesiometer (CBA) before, and at 2 weeks, 1 month, and every month for 6 months after surgery. Preoperative and postoperative measurements were recorded and analyzed with Wilcoxon signed-rank test. The mean patient age was 53.5 years (range 44-68). All patients had nasal primary pterygium and completed the 6-month follow-up. The conjunctival autograft was correctly positioned and fixed in all eyes with fibrin glue. Mean ± SD sensations in conjunctival autograft were none (p<0.05) at 1 month, 4.28 ± 5.34 mm (p<0.05) at 2 months, 12.85 ± 2.67 mm (p<0.05) at 3 months, and returned to normal level, 23.57 ± 2.43 mm (p>0.05), at 4 months. Mean sensations in superior conjunctival area where the autograft was harvested were 11.42 ± 5.56 mm (p<0.05) at 1 month, and returned to normal level, 22.14 ± 2.67 mm (p>0.05), at 2 months. Mean sensations in nasal corneal area after surgery were 7.81 ± 4.06 mm (p<0.05) at 2 weeks, 26.42 ± 2.43 mm (p<0.05) at 1 month, and returned to normal level, 49.00 ± 3.38 mm (p>0.05), at 2 months. Mean sensations in superior corneal area did not change postoperatively. Anesthesia at first month and hypoesthesia at second and third month at conjunctival autograft was observed after pterygium surgery. Additionally, hypoesthesia was observed at nasal cornea and superior bulbar conjunctiva at the first month.

Corneal sensitivity in healthy, immature, and adult alpacas

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.

Assessing the sensory function of the ocular surface: Implications of use of a non-contact air jet aesthesiometer versus the Cochet–Bonnet aesthesiometer

Assessment of corneal sensory function is commonly carried out using the Cochet–Bonnet aesthesiometer. The limitations of this instrument have lead to development of newer instruments, such as the CRCERT–Belmonte aesthesiometer, which utilise a jet of air as their stimulus. Recent work, however, has demonstrated contradictory effects on ocular surface sensitivity when measured with different types of aesthesiometer. The purpose of the present study was to compare clinical measurements of corneal sensitivity obtained with the CRCERT–Belmonte and the Cochet–Bonnet aesthesiometers and to examine their stimulus characteristics in terms of force exerted. No association was found between central corneal sensitivity measured with the two aesthesiometers in a group of normal subjects. Sensitivity was measured to be lower with the Cochet–Bonnet aesthesiometer than with the CRCERT–Belmonte. Over half of the subjects could not be assessed with the standard Cochet–Bonnet filament and 11% could not be assessed with either filament, as their corneal sensitivity was outside of the range of the instrument. In contrast, all subjects were within the stimulus range of the CRCERT–Belmonte aesthesiometer. Corneal sensitivity measurements made with the non-contact CRCERT–Belmonte aesthesiometer and the Cochet–Bonnet aesthesiometer are not comparable. Due to dissimilarities in the composition of their stimuli, and thus mode of stimulation, it is possible that the two instruments measure different aspects of the neural response. The underestimation of corneal sensitivity by the Cochet–Bonnet aesthesiometer and its inability to measure sensitivity of some subjects at all are important considerations in the assessment of sensitivity loss. Subtle changes are unlikely to be detected with this instrument, particularly at higher sensitivity levels. The Cochet–Bonnet should therefore be used with caution and the 0.08mm diameter used as the filament of choice. Adoption of a non-contact aesthesiometer as standard for ocular sensitivity measurement should be considered. The non-contact instrument allows superior stimulus reproducibility and better control over stimulus characteristics, in addition to the ability for exploration of the response of all three types of neuro-receptors on the ocular surface.

Effect of treatment with a topical ophthalmic preparation of 1% nalbuphine solution on corneal sensitivity in clinically normal horses

To assess the effect of treatment with a topical ophthalmic preparation of 1.2% nalbuphine solution on corneal sensitivity in clinically normal horses. 8 horses. Baseline corneal touch threshold (CTT) was measured (defined as the mean filament length [mm] at which a consistent blink response was elicited) for both eyes of each horse by use of a Cochet-Bonnet aesthesiometer. Subsequently, 0.2 mL of 1.2% nalbuphine solution was instilled in 1 randomly selected eye of each horse, and 0.2 mL of artificial tears solution was instilled in the contralateral eye (control treatment). For all 8 horses, CTT of each eye was measured within 1 minute following nalbuphine or artificial tears administration and every 15 minutes thereafter for 60 minutes. For 5 of the 8 horses, CTT was also measured in both eyes at 120 minutes. Changes in CTT values from baseline over time were assessed, as were differences between treated and control eyes. At any time point, corneal sensitivity following nalbuphine treatment did not differ significantly from control treatment findings. Mean CTTs for nalbuphine-treated and control eyes were 38.8 and 37.9 mm, respectively. In both groups, CTT was significantly lower than baseline value at 15, 45, 60, and 120 minutes. No tearing or redness developed in any eye treated with nalbuphine. Topical administration of ophthalmic 1% nalbuphine solution had no effect on corneal sensitivity in clinically normal horses. The topical ocular treatment was not associated with local irritation.

Elevated Nerve Growth Factor in Dry Eye Associated With Established Contact Lens Wear

Nerve growth factor (NGF) has been shown to be upregulated in conditions, which damage corneal nerves and to relieve dry eye. How NGF changes in nerve injury induced by established contact lens wear is not clear. The purpose of this study was to measure the subepithelial nerve plexus and tear NGF and transforming growth factor (TGF)-beta1 levels in patients with established contact lens associated with dry eye. Non-contact lens wearers and subjects who had worn soft contact lenses for more than 1 year were recruited and were divided into three groups: (1) normal controls; (2) contact lens wearers without dry eye; (3) contact lens wearers with dry eye. Corneal sensitivity was measured with a Cochet-Bonnet aesthesiometer. Nerve density and branching in the subepithelial plexus were measured using in vivo confocal microscopy. Tear NGF and TGF-beta1 levels were measured with an enzyme immuno assay. There was a statistically significant decrease of corneal sensitivity in contact lens wearers compared with normal controls. The nerve density in the subepithelial plexus of contact lens wearers with dry eye was 538.8 +/- 39.3 microm/image (3.959 +/- 0.28 pm/microm(2)) and 537.1 +/- 30.9 microm/image (3.947 +/- 0.27 pm/microm(2)) in those without dry eye. Both of these values were significantly (P=0.032) lower than in the normal controls (4.412 +/- 0.21 pm/microm(2)). The concentration of tear NGF was increased in contact lens wearers with dry eye and was statistically significantly greater compared with contact lens wearers without dry eye. Transforming growth factor-beta1 levels were found to increase one fold in contact lens associated dry eye, and were significantly correlated to NGF. Corneal subepithelial nerve density was decreased in long-term contact lens wear but this change was not significantly correlated with tear film NGF concentration. Tear film NGF levels were elevated in contact lens related dry eye, likely in response to anti-inflammatory factors such as TGF-beta1.

Frequent spontaneous eyeblink activity associated with reduced conjunctival surface (trigeminal nerve) tactile sensitivity

A number of recent studies have reported high spontaneous eyeblink rate (SEBR) values in apparently normal subjects, but the reasons for this are unclear. An assessment was made of SEBR, in 60 educated adult male subjects aged between 22 and 40 years, over a period of 5 min in silence. Half of the subjects were classified as having frequent eyeblink activity. All subjects also had their corneal and conjunctival touch (tactile) sensitivity assessed with a Cochet-Bonnet aesthesiometer immediately after the video recording of SEBR. SEBR ranged from 4.6 to 43.5 (mean 18.6) eyeblinks/min. The SEBR was 26.8 +/- 6.0 eyeblinks/min for those with frequent eyeblink activity as compared to just 10.3 +/- 3.5 eyeblinks/min for those with normal eyeblink activity (p < 0.001). There was no difference in palpebral aperture or exposed ocular surface area between the two groups. The average central corneal sensitivity was only marginally different between the two groups (56.8 +/- 2.8 mm vs 58.5 +/- 2.3 mm) but the conjunctival threshold sensitivity was substantially different (at 23.8 +/- 4.3 mm vs 28.5 +/- 3.5 mm; p < 0.001). SEBR was inversely correlated with the conjunctival sensitivity in those with frequent eyeblink activity (p < 0.001). Our study provides a clue as to the mechanism of inhibition of spontaneous eyeblink activity, namely that a certain level of ocular surface (conjunctival) sensitivity is required to keep SEBR low.

Evaluation of duration of corneal anesthesia induced with ophthalmic 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in clinically normal horses

To measure duration of corneal anesthesia and time and degree of maximal anesthetic effect of 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in horses. 10 clinically normal adult horses. Baseline corneal touch threshold (CTT) was measured in millimeters for 1 randomly selected eye of each horse by use of the aesthesiometer by applying the filament to the cornea at maximum length (60 mm) and decreasing in 5-mm increments until a consistent blink response was elicited. Following baseline CTT measurement, 0.2 mL of 0.5% proparacaine hydrochloride was instilled in the selected eye. The CTT was measured within 1 minute following proparacaine administration and every 5 minutes thereafter for 60 minutes. A mixed-model ANOVA with tested eye varying between subjects and measurement time varying within subject was used to test for main effects and any interaction between these factors. A contrast between means of baseline and each subsequent CTT identified the duration of corneal anesthesia as the time at which there was no difference from baseline. Maximal anesthetic effect occurred at the time with the lowest mean CTT. Duration of corneal anesthesia achieved by use of proparacaine was 25 minutes, and maximal anesthetic effect occurred within 5 minutes, although CTT never went to 0 in any horse at any time. Duration of corneal anesthesia in horses was shorter than in dogs, and degree of maximal effect was less than in cats and dogs, most likely because of increased sensitivity of the equine cornea, compared with corneal sensitivity in those species.

Evaluation of duration of corneal anesthesia induced with ophthalmic 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in clinically normal horses

Evaluation of duration of corneal anesthesia induced with ophthalmic 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in clinically normal horses

Reduced tear production in three canine endocrinopathies*

Previous reports have suggested that hypothyroid and diabetic patients can be predisposed to keratoconjunctivitis sicca. This study aimed to measure tear production in dogs with diabetes, hypothyroidism and hyperadrenocorticism using the Schirmer tear test and to compare these results with Schirmer tear test values for a group of normal dogs. Schirmer tear tests were performed on 16 dogs with hyperadrenocorticism, 18 with diabetes and 12 with hypothyroidism together with 100 control dogs. Corneal sensitivity was also measured in 12 of the 18 diabetic dogs with a Cochet Bonnet aesthesiometer and compared with age- and breed-matched normal dogs. Schirmer tear test values in dogs with hypothyroidism, hyperadrenocorticism and diabetes were 12.3+/-3.2, 14.0+/-4.0 and 12.3+/-5.3 mm/minutes, respectively. Schirmer tear test values were significantly lower than that for the control group (19.6+/-4.2 mm/minutes) in all dogs with an endocrinopathy. Only in two hypothyroid dogs and three diabetics, this was manifested as profound keratoconjunctivitis sicca with Schirmer tear test value lower than 5 mm/minutes. Diabetic dogs had significantly reduced corneal sensitivity compared with a matched set of control dogs. This study shows a significant reduction in tear production in animals with diabetes mellitus, hypothyroidism and hyperadrenocorticism. Further research is needed to elucidate the mechanisms by which this reduction in tear production occurs. Assessment of tear production should be undertaken in animals diagnosed with these endocrinopathies, as these animals may progress to clinical keratoconjunctivitis sicca.

Corneal Sensitivity Is Reduced and Relates to the Severity of Neuropathy in Patients With Diabetes

The focus in relation to the consequences of nerve damage in diabetes has been the loss of sensation in the feet predisposing to the development of foot ulceration and lower extremity amputation (1). However, the cornea is 300–600 times more sensitive than skin (2). In addition to serving a protective function, corneal nerves regulate corneal epithelial integrity, proliferation, and wound healing (3). In diabetic patients, corneal sensitivity is reduced (4), due to a loss of corneal nerve fibers (5), which leads to corneal keratopathy (6,7) and a susceptibility to injury, with recurrent erosions and ulcers (8). Thus, these changes are analogous to the diabetic foot, but because the cornea is not exposed to high pressures, ulceration infrequently occurs. Corneal sensation is mediated via myelinated A-δ and C-nerve fibers (9,10), which can be evaluated using the Cochet-Bonnet aesthesiometer (C-BA) (2) or the noncontact corneal aesthesiometer (NCCA) (11), respectively. In diabetic patients, the C-BA has been used to show a reduction in corneal sensitivity in some (12) but not other (13) studies. Furthermore, loss of corneal sensation has been related to the severity of retinopathy (12) and neuropathy (14). We have assessed corneal sensitivity in a large group of diabetic patients using both C-BA and NCCA to assess concordance between the two methods and also to define whether C-nerve fibers are the earliest to undergo damage (15). Using corneal confocal microscopy, we …

Corneal Nerve Structure and Function in Keratoconus: A Case Report

To investigate corneal nerve structure and function in a 24-year-old patient with keratoconus and prominent corneal nerves. Corneal nerve appearance was assessed by using a corneal confocal microscope, and corneal nerve function was assessed by using a Cochet-Bonnet aesthesiometer. Findings were compared to those of an age-matched control subject without keratoconus. The patient with keratoconus was found to have thicker nerve fiber bundles in the stroma (keratoconus vs. control, 9.8 +/- 5.0 microm vs. 5.4 +/- 2.7 microm) and reduced nerve fiber density in the subepithelial plexus (keratoconus vs. control, 269.7 +/- 145.6 microm vs. 1,258 +/- 254.8 mum) compared to the control subject. The patient with keratoconus was found to have reduced corneal sensitivity compared to the control subject (keratoconus vs. control 0.39 gr/mm2 vs. 1.59 gr/mm2). Corneal confocal microscopy proved to be a useful in vivo technique for assessing corneal nerve structure in this patient with keratoconus. Although the total number of stromal nerve fiber bundles was reduced in the patient with keratoconus versus the control subject, the increased tortuosity and increased nerve fiber diameter may explain why the corneal nerves appear more visible in this patient with keratoconus.

Duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in clinically normal cats

To determine duration of corneal anesthesia following topical administration of 0.5% proparacaine hydrochloride solution in domestic shorthair (DSH) cats. 20 clinically normal DSH cats. Baseline corneal touch threshold (CCT) was established by use of a Cochet-Bonnet aesthesiometer. Treatment consisted of a single 50-microL topical application of an ophthalmic preparation of 0.5% proparacaine solution to a randomly selected eye of each cat. The corneal touch threshold was assessed 1 and 5 minutes after application to the cornea and at 5- minute intervals thereafter for 60 minutes. Corneal sensitivity, as determined by Cochet-Bonnet aesthesiometry, was significantly reduced from baseline for 25 minutes following topical administration of ophthalmic proparacaine. Maximal anesthetic effect lasted 5 minutes. As determined by Cochet-Bonnet aesthesiometry, duration of anesthetic effects on the cornea induced by a single topical application of an ophthalmic preparation of 0.5% proparacaine solution in DSH cats is considerably shorter than the reported duration of corneal anesthesia in dogs.

Comparison of the effects of moxifloxacin (0.5%) and gatifloxacin (0.3%) ophthalmic solutions on corneal sensitivity

Purpose This study was designed to evaluate any changes in corneal sensitivity induced by the topical ophthalmic fluoroquinolone solutions moxifloxacin and gatifloxacin compared to placebo. Methods This contralateral, double masked, placebo controlled, three visit study enrolled healthy subjects with normal ocular health. Subjects were randomized to one of three treatment groups, which adhered to 10 days of QID dosing: moxifloxacin in one eye and placebo in the other, gatifloxacin in one eye and placebo in the other, or moxifloxacin in one eye and gatifloxacin in the other. Measurements of corneal sensitivity were recorded at baseline and at the two evaluatory visits (Day 7 and 14). A Cochet-Bonnet aesthesiometer was used to determine corneal sensitivity, as an indicator of any potential ocular neuropathic effects. Results Ninety two subjects completed the study. No significant differences in corneal sensitivity for moxifloxacin, gatifloxacin, or placebo-treated eyes were evident at Day 7 or Day 14 as compared to baseline. Similarly, there were no significant differences in corneal sensitivity measurements between the two fluoroquinolones. Conclusions Though peripheral neuropathies have been reported with use of systemic fluoroquinolones, this does not appear to be the case with ophthalmic fluoroquinolone formulations.

Clinical and cytological findings in limbal stem cell deficiency

To evaluate and relate the clinical (including corneal sensitivity and tear function) and cytological (presence of goblet cells and cytokeratin 3- and 19-positive cells) features of limbal stem cell deficiency (LSCD). Twenty-nine patients (44 eyes) with a clinical diagnosis of LSCD participated in this study. Corneal signs (epithelial alterations, superficial neovascularisation and stromal scarring) and cytological findings (presence of goblet cells and cytokeratins 3 and 19) were evaluated and scored (from 0 to 3) from each of the five corneal sectors. Corneal sensitivity (Cochet-Bonnet aesthesiometer) and tear function (Schirmer test and BUT) were also assessed. Cytological scores were correlated statistically with both corneal signs and sensitivity values. Cytokeratin 19-positive cells were found in 82% of corneal impression cytology samples, while goblet cells were identified in only 59% of these same samples. Cytokeratin 3-positive cells were present in 61% of LSCD eyes and in all unaffected eyes. Corneal sensitivity was significantly decreased in affected eyes compared with contralateral, healthy eyes (1.6+/-1.7 cm versus 5.7+/-0.3 cm). Tear function tests did not show significant changes. In LSCD eyes, goblet cells and cytokeratin 19-positive cells on the corneal surface were significantly correlated to corneal epithelial alterations and to corneal superficial neovascularisation (p<0.001). Corneal cytokeratin 3-positive cells were inversely related to epithelial alterations (p=0.003). Corneal sensitivity was decreased in corneal sectors with epithelial alterations (p<0.001), neovascularisation (p<0.001) and stromal abnormalities (p=0.049), and was indirectly related to the presence of goblet cells (p=0.005) and cytokeratin 19-positive cells (p<0.001). This study confirmed the importance of cytological tests in the diagnosis of LSCD. Furthermore, the absence of goblet cells may not exclude corneal conjunctivalisation as demonstrated by cytokeratin 19 immunostaining. Lastly, corneal conjunctivalisation was associated with zone-specific impairment in corneal sensitivity.

Duration of effect and effect of multiple doses of topical ophthalmic 0.5% proparacaine hydrochloride in clinically normal dogs

To determine the duration of effect and the effect of multiple doses of topical ophthalmic application of 0.5% proparacaine hydrochloride on corneal sensitivity in clinically normal dogs. 8 clinically normal dogs. Dogs were randomly allocated to treatment order in a 2 x 2 (period X treatment) crossover study. Treatments consisted of topical application of ophthalmic 0.5% proparacaine (1 drop or 2 drops at a 1-minute interval); treatments were applied to both eyes. A Cochet-Bonnet aesthesiometer was used to determine corneal touch threshold (CTT) before corneal application, 1 and 5 minutes after corneal application, and at 5-minute intervals thereafter for 90 minutes. The CTT value before treatment differed significantly from CTT values after treatment until 45 minutes after application in the 1-drop group and until 55 minutes after application in the 2-drop group. As determined by use of the Cochet-Bonnet aesthesiometer, a significantly greater anesthetic effect was detected for the 2-drop treatment, compared with the effect for the 1-drop treatment, at 30, 35, 40, 45, 50, and 55 minutes after application. Maximal anesthetic effect lasted for 15 minutes for the 1-drop treatment and 25 minutes for the 2-drop treatment. Duration of corneal anesthetic effect induced by topical ophthalmic application of 0.5% proparacaine in dogs of this study is considerably longer than that reported elsewhere. Serial application of doses of 0.5% proparacaine increases the duration and magnitude of corneal anesthetic effects.

Morphology of corneal nerves and corneal sensation in dry eye: a preliminary study

To evaluate the corneal sensitivity and nerve morphology in dry eyes. A total of 32 eyes of 16 patients (10 Sjogren's syndrome and six non-Sjogren's syndrome) and 19 eyes of 10 age-matched controls were studied. Sensitivity of the central cornea was measured by the Cochet-Bonnet aesthesiometer. The morphology of corneal nerves was studied by in vivo confocal microscopy (ConfoScan 2.0, Fortune Technologies Srl, Vigonza (PD), Italy). Sub-basal epithelial nerve plexus, subepithelial nerve plexus, and stromal nerves were localized and evaluated for the number of nerves, thickness, reflectivity, and tortuosity for each frame. The mean corneal sensitivity of dry eye patients (5.6 mm/grs/S) was found significantly lower than that of the control (5.0 mm/grs/S) group (P<0.01). Although the subepithelial nerves were thicker in dry eyes (mean: 6.38+/-1.18 microm) than control eyes (mean: 5.72+/-1.27 microm), this difference was not significant (P>0.05). Decreased corneal sensitivity is not associated with morphological changes of corneal nerves in dry eyes.