Latent autoimmune diabetes of adulthood (LADA) is associated with small fibre neuropathy.

AIM: To assess if latent autoimmune diabetes of adulthood (LADA) is associated with small fibre neuropathy. METHODS: Participants with LADA (n=31), Type 2 diabetes (n=31) and healthy control participants without diabetes (n=31) underwent a detailed assessment of neurologic deficits, quantitative sensory testing, electrophysiology, skin biopsy and corneal confocal microscopy. RESULTS: The groups were matched for age (healthy control without diabetes: 53.5±9.1 vs. Type 2 diabetes: 58.0±6.5 vs. LADA: 53.2±11.6 years), duration of diabetes (Type 2 diabetes: 10.0±8.3 vs. LADA: 11.0±9.1 years) and blood pressure. However, BMI (P=0.01) and triglycerides (P=0.0008) were lower and HbA1c (P=0.0005), total cholesterol (P=0.01) and HDL (P=0.002) were higher in participants with LADA compared with Type 2 diabetes. Peroneal motor nerve conduction velocity (P=0.04) and sural sensory nerve conduction velocity (P=0.008) were lower in participants with latent autoimmune diabetes in adults compared with Type 2 diabetes. Intra-epidermal nerve fibre density (P=0.008), corneal nerve fibre density (P=0.003) and corneal nerve branch density (P=0.006) were significantly lower in participants with LADA compared with Type 2 diabetes. There were no significant differences in the other neuropathy parameters. CONCLUSIONS: Despite comparable age and duration of diabetes, participants with LADA demonstrate more severe neuropathy and particularly small fibre neuropathy, compared with participants with Type 2 diabetes.

Malaria risk in Nigeria: Bayesian geostatistical modelling of 2010 malaria indicator survey data.

BACKGROUND: In 2010, the National Malaria Control Programme with the support of Roll Back Malaria partners implemented a nationally representative Malaria Indicator Survey (MIS), which assembled malaria burden and control intervention related data. The MIS data were analysed to produce a contemporary smooth map of malaria risk and evaluate the control interventions effects on parasitaemia risk after controlling for environmental/climatic, demographic and socioeconomic characteristics. METHODS: A Bayesian geostatistical logistic regression model was fitted on the observed parasitological prevalence data. Important environmental/climatic risk factors of parasitaemia were identified by applying Bayesian variable selection within geostatistical model. The best model was employed to predict the disease risk over a grid of 4 km(2) resolution. Validation was carried out to assess model predictive performance. Various measures of control intervention coverage were derived to estimate the effects of interventions on parasitaemia risk after adjusting for environmental, socioeconomic and demographic factors. RESULTS: Normalized difference vegetation index and rainfall were identified as important environmental/climatic predictors of malaria risk. The population adjusted risk estimates ranges from 6.46% in Lagos state to 43.33% in Borno. Interventions appear to not have important effect on malaria risk. The odds of parasitaemia appears to be on downward trend with improved socioeconomic status and living in rural areas increases the odds of testing positive to malaria parasites. Older children also have elevated risk of malaria infection. CONCLUSIONS: The produced maps and estimates of parasitaemic children give an important synoptic view of current parasite prevalence in the country. Control activities will find it a useful tool in identifying priority areas for intervention.

Standardizing corneal nerve fibre length for nerve tortuosity increases its association with measures of diabetic neuropathy.

AIMS: Recent studies on corneal markers have advocated corneal nerve fibre length as the most important measure of diabetic peripheral neuropathy. The aim of this study was to determine if standardizing corneal nerve fibre length for tortuosity increases its association with other measures of diabetic peripheral neuropathy. METHODS: Two hundred and thirty-one individuals with diabetes with either predominantly mild or absent neuropathic changes and 61 control subjects underwent evaluation of diabetic neuropathy symptom score, neuropathy disability score, testing with 10-g monofilament, quantitative sensory testing (warm, cold, vibration detection) and nerve conduction studies. Corneal nerve fibre length and corneal nerve fibre tortuosity were measured using corneal confocal microscopy. A tortuosity-standardised corneal nerve fibre length variable was generated by dividing corneal nerve fibre length by corneal nerve fibre tortuosity. Differences in corneal nerve morphology between individuals with and without diabetic peripheral neuropathy and control subjects were determined and associations were estimated between corneal morphology and established tests of, and risk factors for, diabetic peripheral neuropathy. RESULTS: The tortuosity-standardised corneal nerve fibre length variable was better than corneal nerve fibre length in demonstrating differences between individuals with diabetes, with and without neuropathy (tortuosity-standardised corneal nerve fibre length variable: 70.5 ± 27.3 vs. 84.9 ± 28.7, P < 0.001, receiver operating characteristic area under the curve = 0.67; corneal nerve fibre length: 15.9 ± 6.9 vs. 18.4 ± 6.2 mm/mm², P = 0.004, receiver operating characteristic area under the curve = 0.64). Furthermore, the tortuosity-standardised corneal nerve fibre length variable demonstrated a significant difference between the control subjects and individuals with diabetes, without neuropathy, while corneal nerve fibre length did not (tortuosity-standardised corneal nerve fibre length variable: 94.3 ± 27.1 vs. 84.9 ± 28.7, P = 0.028; corneal nerve fibre length: 20.1 ± 6.3 vs. 18.4 ± 6.2 mm/mm², P = 0.084). Correlations between corneal nerve fibre length and established measures of neuropathy and risk factors for neuropathy were higher when a correction was made for the nerve tortuosity. CONCLUSIONS: Standardizing corneal nerve fibre length for tortuosity enhances the ability to differentiate individuals with diabetes, with and without neuropathy.

Visual sensitivity loss in the central 30° of visual field is associated with diabetic peripheral neuropathy.

AIMS/HYPOTHESIS: Impaired central vision has been shown to predict diabetic peripheral neuropathy (DPN). Several studies have demonstrated diffuse retinal neurodegenerative changes in diabetic patients prior to retinopathy development, raising the prospect that non-central vision may also be compromised by primary neural damage. We hypothesise that type 2 diabetic patients with DPN exhibit visual sensitivity loss in a distinctive pattern across the visual field, compared with a control group of type 2 diabetic patients without DPN. METHODS: Increment light sensitivity was measured by standard perimetry in the central 30° of visual field for two age-matched groups of type 2 diabetic patients, with and without neuropathy (n = 40/30). Neuropathy status was assigned using the neuropathy disability score. Mean visual sensitivity values were calculated globally, for each quadrant and for three eccentricities (0-10°, 11-20° and 21-30°). Data were analysed using a generalised additive mixed model (GAMM). RESULTS: Global and quadrant between-group visual sensitivity mean differences were marginally but consistently lower (by about 1 dB) in the neuropathy cohort compared with controls. Between-group mean differences increased from 0.36 to 1.81 dB with increasing eccentricity. GAMM analysis, after adjustment for age, showed these differences to be significant beyond 15° eccentricity and monotonically increasing. Retinopathy levels and disease duration were not significant factors within the model (p = 0.90). CONCLUSIONS/INTERPRETATION: Visual sensitivity reduces disproportionately with increasing eccentricity in type 2 diabetic patients with peripheral neuropathy. This sensitivity reduction within the central 30° of visual field may be indicative of more consequential loss in the far periphery.

Retinal nerve fibre layer thinning associated with diabetic peripheral neuropathy.

AIMS: To investigate the relationship between retinal nerve fibre layer thickness and peripheral neuropathy in patients with Type 2 diabetes, particularly in those who are at higher risk of foot ulceration. METHODS: Global and sectoral retinal nerve fibre layer thicknesses were measured at 3.45 mm diameter around the optic nerve head using optical coherence tomography (OCT). The level of neuropathy was assessed in 106 participants (82 with Type 2 diabetes and 24 healthy controls) using the 0-10 neuropathy disability score. Participants were stratified into four neuropathy groups: none (0-2), mild (3-5), moderate (6-8), and severe (9-10). A neuropathy disability score ≥ 6 was used to define those at higher risk of foot ulceration. Multivariable regression analysis was performed to assess the effect of neuropathy disability scores, age, disease duration and retinopathy on RNFL thickness. RESULTS: Inferior (but not global or other sectoral) retinal nerve fibre layer thinning was associated with higher neuropathy disability scores (P = 0.03). The retinal nerve fibre layer was significantly thinner for the group with neuropathy disability scores ≥ 6 in the inferior quadrant (P < 0.005). Age, duration of disease and retinopathy levels did not significantly influence retinal nerve fibre layer thickness. Control participants did not show any significant differences in thickness measurements from the group with diabetes and no neuropathy (P > 0.24 for global and all sectors). CONCLUSIONS: Inferior quadrant retinal nerve fibre layer thinning is associated with peripheral neuropathy in patients with Type 2 diabetes, and is more pronounced in those at higher risk of foot ulceration.

Corneal confocal microscopy detects improvement in corneal nerve morphology with an improvement in risk factors for diabetic neuropathy.

AIM: We have assessed whether corneal confocal microscopy can be used to detect alterations in nerve morphology following an improvement in risk factors associated with diabetic neuropathy. METHODS: Twenty-five patients with diabetes with mild to moderate neuropathy and 18 control subjects underwent corneal confocal microscopy to quantify corneal nerve fibre (density, branch density, length and tortuosity) at baseline and after 24 months from first visit. This was not planned as an intervention trial and was simply an observational follow-up. RESULTS: At baseline, nerve fibre density (18.8 ± 2.1 vs. 46.0 ± 3.8 number/mm(2), P = 0.001), nerve branch density (6.9 ± 1.5 vs. 35.6 ± 6.7 number/mm(2), P < 0.0001), nerve fibre length (8.3 ± 0.9 vs. 13.5 ± 0.8 mm/mm(2), P < 0.0001) and nerve fibre tortuosity (19.8 ± 1.6 vs. 22.7 ± 2.2, P < 0.05) were significantly lower in patients with diabetes than in control subjects. At follow-up, glycaemic control (HbA(1c) 64 ± 3 to 58 ± 2 mmol/mol, P = 0.08), total cholesterol (4.9 ± 0.2 to 4.2 ± 0.2 mmol/l, P = 0.01), systolic blood pressure (145.8 ± 4.9 to 135.9 ± 3.7 mmHg, P = 0.09) and diastolic blood pressure (77.8 ± 2.7 to 70.8 ± 2.5, P = 0.03) improved. Nerve fibre density (24.1 ± 2.0, P = 0.05), nerve branch density (11.1 ± 1.3, P < 0.01) and nerve fibre tortuosity (22.6 ± 1.5, P = 0.05) increased significantly, with no change in nerve fibre length (8.4 ± 0.5). Improvement in nerve fibre density correlated significantly with the improvement in HbA(1c) (r = -0.51, P = 0.008). Via four multifactorial regressions, this confirms the negative association between HbA(1c) and nerve fibre density (P = 0.02). CONCLUSIONS: This study shows that corneal confocal microscopy may be employed in longitudinal studies to assess progression of human diabetic neuropathy and also supports the hypothesis that improvements in risk factors for diabetic neuropathy, in particular HbA(1c) , may lead to morphological repair of nerve fibres.

Increased Langerhan cell density and corneal nerve damage in diabetic patients: role of immune mechanisms in human diabetic neuropathy.

AIM/HYPOTHESIS: Immune mechanisms have been proposed to play a role in the development of diabetic neuropathy. We employed in vivo corneal confocal microscopy (CCM) to quantify the presence and density of Langerhans cells (LCs) in relation to the extent of corneal nerve damage in Bowman's layer of the cornea in diabetic patients. METHODS: 128 diabetic patients aged 58 ± 1 yrs with a differing severity of neuropathy based on Neuropathy Deficit Score (NDS-4.7 ± 0.28) and 26 control subjects aged 53 ± 3 yrs were examined. Subjects underwent a full neurological evaluation, evaluation of corneal sensation with non-contact corneal aesthesiometry (NCCA) and corneal nerve morphology using corneal confocal microscopy (CCM). RESULTS: The proportion of individuals with LCs was significantly increased in diabetic patients (73.8%) compared to control subjects (46.1%), P = 0.001. Furthermore, LC density (no/mm(2)) was significantly increased in diabetic patients (17.73 ± 1.45) compared to control subjects (6.94 ± 1.58), P = 0.001 and there was a significant correlation with age (r = 0.162, P = 0.047) and severity of neuropathy (r = -0.202, P = 0.02). There was a progressive decrease in corneal sensation with increasing severity of neuropathy assessed using NDS in the diabetic patients (r = 0.414, P = 0.000). Corneal nerve fibre density (P < 0.001), branch density (P < 0.001) and length (P < 0.001) were significantly decreased whilst tortuosity (P < 0.01) was increased in diabetic patients with increasing severity of diabetic neuropathy. CONCLUSION: Utilising in vivo corneal confocal microscopy we have demonstrated increased LCs in diabetic patients particularly in the earlier phases of corneal nerve damage suggestive of an immune mediated contribution to corneal nerve damage in diabetes.

Incidence of keratitis of varying severity among contact lens wearers.

AIM: To determine the incidence of non-severe keratitis (NSK) and severe keratitis (SK) among wearers of current generation contact lenses. METHODS: A 12 month, prospective, hospital based epidemiological study was conducted by examining all contact lens wearers presenting with a corneal infiltrate/ulcer to a hospital centre in Manchester. A clinical severity matrix was used to differentiate between NSK and SK, based on the severity of signs and symptoms. The size of the hospital catchment population and the wearing modalities (daily wear (DW) or extended wear (EW)) and lens types being used were estimated from relevant demographic and market data. RESULTS: During the survey period, 80 and 38 patients presented with NSK and SK, respectively. The annual incidences (cases per 10,000 wearers) for each wearing modality and lens type were: DW rigid--NSK 5.7, SK 2.9; DW hydrogel daily disposable--NSK 9.1, SK 4.9; DW hydrogel (excluding daily disposable)--NSK 14.1, SK 6.4; DW silicone hydrogel--NSK 55.9, SK 0.0; EW rigid--NSK 0.0, SK 0.0; EW hydrogel--NSK 48.2, SK 96.4; EW silicone hydrogel--NSK 98.8, SK 19.8. The difference in SK between EW hydrogel and EW silicone hydrogel was significant (p = 0.04). CONCLUSIONS: A clinical severity matrix has considerable utility in assessing contact lens related keratitis. There is a significantly higher incidence of SK in wearers who sleep in contact lenses compared with those who only use lenses during the waking hours. Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which carry a five times decreased risk of SK for extended wear compared with hydrogel lenses.

Corneal confocal microscopy: a non-invasive surrogate of nerve fibre damage and repair in diabetic patients.

AIMS/HYPOTHESIS: The accurate detection, characterization and quantification of human diabetic neuropathy are important to define at risk patients, anticipate deterioration, and assess new therapies. Corneal confocal microscopy is a reiterative, rapid, non-invasive in vivo clinical examination technique capable of imaging corneal nerve fibres. The aim of this study was to define the ability of this technique to quantify the extent of degeneration and regeneration of corneal nerve fibres in diabetic patients with increasing neuropathic severity. METHODS: We scanned the cornea and collected images of Bowman's layer (containing a rich nerve plexus) from 18 diabetic patients and 18 age-matched control subjects. RESULTS: Corneal nerve fibre density (F(3)=9.6, p<0.0001), length (F(3)=23.8, p<0.0001), and branch density (F(3)=13.9, p<0.0001) were reduced in diabetic patients compared with control subjects, with a tendency for greater reduction in these measures with increasing severity of neuropathy. CONCLUSION/INTERPRETATION: Corneal confocal microscopy is a rapid, non-invasive in vivo clinical examination technique which accurately defines the extent of corneal nerve damage and repair and acts as a surrogate measure of somatic neuropathy in diabetic patients. It could represent an advance to define the severity of neuropathy and expedite assessment of therapeutic efficacy in clinical trials of human diabetic neuropathy.

A population study of the normal cornea using an in vivo, slit-scanning confocal microscope.

PURPOSE: To document qualitative and quantitative changes in the normal, healthy human cornea with age using the confocal microscope. METHODS: The central corneas of 120 subjects (mean age, 41 years; range, 11 to 80 years) were examined using an in vivo slit-scanning real-time confocal microscope. Images of the corneal stroma and endothelium from both eyes of each subject were semiautomatically analyzed in an observer-masked, randomized manner. RESULTS: Anterior keratocyte density, posterior keratocyte density, and endothelial cell density were shown to be unaffected by the sex of the subject with p values of 0.46, 0.55, 0.50, respectively (multivariate analysis of variance). No statistically significant difference was detected between right and left eyes for all corneal layers examined. The anterior keratocyte density, posterior keratocyte density, and endothelial cell density decreased at a rate of 0.48, 0.22, and 0.33% per year, respectively. A positive correlation was found between the coefficient of cell variation and age. CONCLUSIONS: This data constitutes essential normative data that can be used as a control in further research into abnormal corneal conditions.

Thermal consequences of photorefractive keratectomy.

PURPOSE: Photorefractive keratectomy (PRK) is still a widely used method for the correction of refractive error despite the advent of laser in situ keratomileusis (LASIK). However, both procedures are associated with significant side effects such as corneal haze and regression. Several factors have been implicated in the etiology of haze, one of which is thermal loading of the cornea. The purpose of this study was to investigate the temperature changes occurring during PRK when performed at different ablation depths. METHODS: Noncontact, color-coded ocular thermography was performed with an infrared detector apparatus during PRK ablation on 19 ovine corneas. Five different refractive corrections were carried out ranging from -2.00 diopters (D) (ablation depth, 31.2 microm) to -10.00 D (ablation depth, 137.9 microm). RESULTS: A temperature rise at the corneal surface was demonstrated in all 19 corneas. The mean rise in temperature was 7.35 +/- 1.13 degrees C with a maximum rise in temperature of 8.97 degrees C. A positive correlation was found between the refractive correction and the peak rise in temperature (r2 = 0.57, p< 0.0001). The rate of temperature change was greater for smaller treatments than for larger treatments (r2 = 0.79, p < 0.0001). Corneas undergoing larger treatments were subject to greater rises in temperature for longer periods of time. CONCLUSIONS: This study suggests that the cornea undergoes a significant rise in temperature as a result of the PRK process. Further investigation is required to determine what effect this thermal loading has on the corneal wound healing response after PRK.

Morphology of corneal nerves using confocal microscopy.

PURPOSE: The aim of the current study was to evaluate the distribution and morphology of corneal nerves as seen by means of white light confocal microscopy. METHODS: This study analyzed images of corneal nerves that were obtained using the Tomey Confoscan slit scanning confocal microscope (40x/0.75 objective lens). The images were classified according to their location within the cornea. The objective and subjective evaluation of the images involved measuring, grading, or judging a number of parameters from both individual pictures and from each single nerve fiber within any image. RESULTS: The in vivo observations made in this work are in agreement with those of previous histologic studies. The general scheme of corneal innervation is described as originating from thick and straight stromal nerve trunks that extend lateral and anteriorly and give rise to plexiform arrangements of progressively thinner nerve fibers at several levels within the stroma. From there, nerve fibers perforate Bowman's layer and eventually form a dense neural plexus just beneath the basal epithelial cell layer, which is characterized by tortuous and thin beaded nerve fibers interconnected by numerous nerve elements; nerve fibers from this plexus are known to be responsible for the innervation of the epithelium. CONCLUSION: This study provides convincing evidence of the suitability of confocal microscopy to image corneal nerves, the only drawback being the limited resolution in terms of the differentiation of the ultrastructure of nerve bundles.

A prospective study of contact lens wear in diabetes mellitus.

A prospective, controlled, observer-masked study was conducted to investigate the suitability of contact lenses for patients with diabetes mellitus. Forty diabetic patients and 40 non-diabetic control subjects were fitted with soft hydrogel contact lenses to be worn on a daily wear basis for 12 months. The ocular response was assessed using slit lamp biomicroscopy, ultrasonic pachometry, corneal aesthesiometry and visual acuity measures. Compared to non-diabetic subjects, diabetic patients displayed significantly reduced corneal transparency, variable vision and reduced comfort with the contact lenses (p < 0.05). There were no significant differences between the two groups with respect to ocular hyperaemia, corneal staining, corneal thickness, corneal sensitivity or high contrast visual acuity. Contrary to previous reports, the response of the diabetic eye to contact lenses--as observed clinically--does not differ appreciably from that of the non-diabetic eye. These results suggest that current generation daily wear soft contact lenses can be a viable mode of vision correction for diabetic patients.

Validation of grading scales for contact lens complications.

The validity of use of two artist-rendered and two photographic sets of grading scales (grading 'systems') designed for gauging the severity of contact lens-related ocular pathology was assessed in terms of precision and reliability. Thirteen observers each graded 30 images--by interpolation or extrapolation to the nearest 0.1 increment--of each of the three contact lens complications (corneal staining, conjunctival redness and papillary conjunctivitis) that were common to all four grading systems. This entire procedure was repeated approximately two weeks later, yielding a total data base comprising of 9360 individual grading estimates. Analysis of variance revealed statistically significant differences in both precision and reliability between systems, observers and conditions (p < 0.03 for system reliability; p = 0.0001 for all other combinations). The artist-rendered systems generally afforded lower grading estimates and better grading reliability than the photographic systems. Corneal staining could be graded less reliably than conjunctival redness and papillary conjunctivitis. Grading reliability was generally unaffected by the severity of the condition being assessed. Notwithstanding the above differences, all four grading systems are validated for clinical use and practitioners can initially expect to use these systems with average 95% confidence limits of +/- 1.2 grading scale units (observer range +/- 0.7 to +/- 2.5 grading scale units). In view of the significant between-system differences revealed in this study, it is advisable to consistently use the same grading system. It may be possible to reduce between-observer differences by applying personalised correction factors to normalise grading estimates.

Confocal microscopy of the normal human cornea.

The slit-scanning confocal microscope is a new clinical paradigm that allows the living human cornea to be viewed at a magnification of 680 x and a lateral resolution of 1 mum. As such, it allows corneal morphology to be inspected at a cellular level. The corneas of both eyes of 119 subjects who were evenly distributed in age from 10-80 years were examined using a Tomey ConfoScan P4 in-vivo slit-scanning real-time confocal microscope (Erlangen, Germany). Good quality representative images of the various corneal layers were selected for detailed qualitative analysis and are displayed here. A grid of corneal layer versus age was constructed from these images; this tool can be used as a normative confocal microscopy reference against which suspected corneal abnormalities can be assessed.

The role of tear physiology in ocular surface temperature.

PURPOSE: To determine whether the more rapid cooling of the tear film in dry eyes is related to other tear film parameters, a battery of tear physiology tests was performed on dry eye patients and control subjects. METHODS: Tear evaporation rate was measured with a modified Servomed (vapour pressure) evaporimeter and ocular temperature with an NEC San-ei 6T62 Thermo Tracer in 9 patients diagnosed as having dry eye and in 13 healthy control subjects. Variability in temperature across the ocular surface was described by the temperature variation factor (TVF). Lipid layer structure and tear film stability were assessed with the Keeler Tearscope and tear osmolality was measured by freezing point depression nanolitre osmometry. RESULTS: The data were explored by principal component analysis. The subjects with and without dry eye could be separated into two distinct groups entirely on the basis of their tear physiology. Dry eye patients exhibited higher tear evaporation rates, osmolalities and TVF, lower tear film stabilities and poorer-quality lipid layers than the control subjects. A significant linear relationship was found to exist between tear evaporation rate and TVF for all subjects (R2 = 0.242, p = 0.024). CONCLUSIONS: Rapid cooling of the tear film in dry eyes appears to be related to the reduced stability of the tears and the increased rate of evaporation. The higher latent heat of vaporisation, associated with the increased evaporation in dry eyes, may account for the increased rate of cooling of the tear film in this condition.

Hydrogel contact lens ageing.

PURPOSE: To determine if hydrogel lens water content decreases over wearing periods of up to four weeks; that is, demonstrate an 'ageing' effect. METHODS: Six subjects (4 males, 2 females; age range: 34.8 +/- 11.0 years) wore each of the following lenses for one month: Acuvue, Frequency 38, Gentle Touch and Proclear. Pre-insertion and post-removal lens water content was measured daily by the subjects using an Atago CL-1 Soft Contact Lens Refractometer for a 28 day period. Post-insertion and pre-removal comfort was recorded over the same period. RESULTS: A significant lens ageing effect was noted whereby the pre-insertion lens water content decreased significantly over the 28 day cycle for all lenses (P < 0.05). The pattern for daily dehydration remained consistent for the 28 day period for the Acuvue lens and the Gentle Touch lens but decreased for the Frequency 38 lens and the Proclear lens. Comfort decreased significantly by the end of the day for three of the four lens types investigated. CONCLUSIONS: It is apparent that the extent of lens dehydration changes over time, and that this pattern of change is different for different lens types. The associated loss of oxygen performance with dehydration is demonstrated. These data will assist practitioners in understanding the clinical effects of soft lens dehydration over time.

Ocular temperature in carotid artery stenosis.

PURPOSE: To explore the potential application of wide-field, color-coded infrared ocular thermography in the investigation of carotid artery stenosis (CAS). METHODS: Ocular thermography and color duplex ultrasonography were undertaken in a masked study of 24 asymptomatic, consecutively presenting patients who were examined for vascular occlusive disease. RESULTS: Linear regression analysis indicated that there was a significant negative correlation between ocular surface temperature and the degree of CAS (r = -0.67, p < 0.001). Similar results were demonstrated between the relative difference in CAS (right - left) and the relative difference in ocular surface temperature (right - left) (r = -0.67, p < 0.001). CONCLUSIONS: These results indicate that the circle of Willis and the other anastomoses within the brain are unable to compensate fully for the reduction in blood flow on the affected side. Noncontact ocular temperature measurement has potential as both a screening test and a supplementary diagnostic clinical test for CAS.