The role of vision-related problems in fatal road accidents in Finland.

PURPOSE: To evaluate the significance of vision-related problems in fatal motor vehicle accidents (FMVAs) based on a systematic investigation process by multidisciplinary road accident investigation teams (RAITs). METHODS: Retrospective registry-based study of all FMVAs during the years 2012-2016 in Finland in which driver causing the accident had a valid Finnish driving licence and the operated motor vehicle required having a driving licence. RESULTS: There were a total of 968 FMVAs. In only 1.3% of all the accidents, a vision-related problem was considered to have contributed to the FMVA, while an observational failure of 23.6% was the leading cause of all the FMVAs. CONCLUSIONS: Eye-originating vision problems are rarely a causative risk for FMVAs in Finland. Making current visual standards more stringent would unlikely to be effective in FMVA prevention.

The most difficult at-fault fatal crashes to avoid with current active safety technology.

OBJECTIVE: We studied which current fatal at-fault crashes would occur despite the most advanced current active safety devices (up to SAE level 2 of driving automation) and how frequent these crashes would be. METHODS: We carried out a cross-sectional study of passenger cars that were first registered during the period 1st January 2010 to 31st December 2017 in Finland. To gain the true exposure for these cars, we accessed the national Vehicular and Driver Data Register to obtain the mileage information and the registration count for the study period of 2010-17. Similarly, we accessed the registry of Finnish road accident investigation teams and included all fatal at-fault crashes among the cars in our study for the same period. We used a real world reference technology for each active safety system in our analysis and chose one car brand as an example. This gave us exact system specifications and enabled testing the operation of the systems on the road. We performed field tests to gain further information on the precise operation of the safety systems in different operating conditions. Finally, we gathered all information on the studied active safety systems and analyzed the investigated at-fault fatal crashes case-by-case using our four level method. RESULTS: Cars in our study were the primary party in 113 investigated fatal accidents during the years 2010-17. In 87 of the accidents, the leading cause of death was the injuries due to the crash, and these cases were classified as "unavoidable" (n = 58, 67 %), "avoidable" (n = 26, 30 %) or unsolved (n = 3, 3 %). Of the 58 "unavoidable" crashes 21 (36 %) were suicides, 21 (36%) involved active driver input which would have prevented the safety system operation, 15 (17 %) featured circumstances beyond the safety system performance and in one loss-of-control crash the driver had disabled the relevant safety system (electronic stability control). The registration years of the cars in our study (2010-17) totaled 3,772,864 and during this period, the cars travelled 75.9 billion kilometers. The crash incidence of the "unavoidable" at-fault fatal crashes was 0.76-0.80 fatal crashes per billion kilometers and 15-16 fatal crashes per million registration years. CONCLUSIONS: We calculated a crash incidence for the "unavoidable" crashes which was 20-27% smaller than the observed crash rate of ESC-fitted passenger cars in our previous study. We concluded that suicides, active driver input until the crash, and challenging weather and road conditions are the most difficult factors for current active safety systems. Our analysis did not account for issues such as system usability or driver acceptance and therefore our results should be regarded as something that is currently theoretically achievable. However, the observed incidence is a good reference for automated driving development and the crash rate of automated cars.

Suicide by crashing into a heavy vehicle: Focus on professional drivers using in-depth crash data.

Objective: Road traffic suicides typically involve a passenger car driver crashing his or her vehicle into a heavy vehicle, because death is almost certain due to the large mass difference between these vehicles. For the same reason, heavy-vehicle drivers typically suffer minor injuries, if any, and have thus received little attention in the research literature. In this study, we focused on heavy-vehicle drivers who were involved as the second party in road suicides in Finland. Methods: We analyzed 138 road suicides (2011-2016) involving a passenger car crashing into a heavy vehicle. We used in-depth road crash investigation data from the Finnish Crash Data Institute. Results: The results showed that all but 2 crashes were head-on collisions. Almost 30% of truck drivers were injured, but only a few suffered serious injuries. More than a quarter reported sick leave following their crash. Injury insurance compensation to heavy-vehicle drivers was just above €9,000 on average. Material damage to heavy vehicles was significant, with average insurance compensation paid being €70,500. Three out of 4 truck drivers reported that drivers committing suicide acted abruptly and left them little opportunity for preventive action. Conclusions: Suicides by crashing into heavy vehicles can have an impact on drivers' well-being; however, it is difficult to see how heavy-vehicle drivers could avoid a suicide attempt involving their vehicle.

Crash risk of ESC-fitted passenger cars.

Objective: We examined both fatal and injury at-fault crashes of a population of passenger cars fitted with electronic stability control (ESC). Crash rates were calculated in relation to both registration years and mileage. Crash rates were also calculated for a non-ESC car population and crash rate ratios were calculated to compare the crash risk between ESC-fitted and non-ESC-fitted passenger cars. Methods: Passenger car models with and without ESC were identified (ESC-equipped cars: 3,352,813 registration years; non-ESC-equipped: 5,839,946 registration years) and their vehicle information for the period 2009-2013, including mileage (ESC-equipped vehicles: 89.3 billion kilometers; non-ESC-equipped: 72.4 billion kilometers), was drawn from the national Vehicular and Driver Data Register. The registry of Finnish road accident investigation teams was accessed and all fatal at-fault crashes among the cars in the study populations (ESC 97; non-ESC 377) for the period 2009-2013 were analyzed. The motor insurance database includes at-fault crashes leading to injuries and was utilized for analyses (ESC: N = 8,827, non-ESC: N = 21,437). Crash rates and crash rate ratios were calculated to evaluate crash risk of both ESC-equipped and non-ESC-equipped passenger cars. Poisson regression was used to model crash involvement rate ratios both per registration year and per mileage for vehicles with ESC and without ESC, controlling for age and gender of the vehicle owner and vehicle mass. Results: Passenger cars fitted with ESC showed lower crash rates than non-ESC-equipped cars in all crash types studied. In general, the difference in crash rates between ESC-equipped and non-ESC-equipped vehicles was greater when the crashes were compared to the mileage rather than registration years. The mileage-proportional crash rate of ESC-equipped cars was 64% (95% confidence interval, 61%; 67%) lower in run-off-road crashes resulting in injury and as much as 82% (65%; 91%) lower in fatal run-off-road crashes when suicides and disease attacks were not taken into account. Conclusions: Our results show that modern passenger cars provide a significant crash risk reduction, which depends on both ESC and passive safety features introduced. Results also show that exposure evaluation in terms of registration years (or vehicle population) instead of true mileage can provide an overly pessimistic view of the crash risk.

Assessment of driving fitness among patients with alcohol-related visits to two hospitals in eastern Finland.

OBJECTIVE: The aim of the present study was twofold. The first aim was to explore how frequently physicians evaluate driving fitness when a patient has a serious alcohol problem, which is accomplished by examining differences in physicians' compliance with their intervention/notification obligation among different alcohol-related ICD-10 diagnoses. The second aim was to explore how many heavy alcohol users have a valid driving license. METHODS: Data from all patients with an alcohol-related ICD-10 diagnosis code as a cause of a hospital visit were collected during a three-month period from Kuopio University Hospital and North Karelia Central Hospital. RESULTS: Eighty-one percent (81%) of patients with alcohol-related ICD-10 diagnoses were heavy alcohol users and had alcohol withdrawal syndrome, alcohol-related organ disease or multidrug abuse combined with alcohol abuse. The driving fitness of these patients was significantly reduced, and the health requirements of the driving license were not met. Physicians evaluated driving fitness for only 20% of alcohol-related hospital visits/hospitalisations. Moreover, fitness to drive was evaluated in only 24% of cases of a patient with a major alcohol problem and a valid driving license. Driving fitness was most frequently evaluated in cases with alcohol-related convulsions (74%). In total, 80% of patients with a major alcohol problem had a valid driving license even though the requirements of driving fitness were not met. CONCLUSIONS: The obligation to evaluate the driving fitness of heavy alcohol users is often neglected, except in cases of alcohol-abuse-related convulsions. Physicians should play a greater role in monitoring road safety, or sanctions should be set for failures to obey the obligations. The driving fitness of a patient hospitalised due to alcohol use should be assessed more regularly. Cognition problems related to alcohol-related liver disease/alcohol-related dementia are probably often overlooked. Alcohol-abuse-related conditions are poorly recognised and remain unreported to the authorities.

Sleep versus non-sleep-related fatal road accidents.

OBJECTIVE: To study different factors that are associated with fatal sleepiness-related motor vehicle accidents (FSMVA) and in other types of fatal motor vehicle accidents (FMVA) in Finland. METHODS: All FMVA that were caused by falling asleep at the wheel (FSMVA) during the years 2005-2014 were investigated using OTI (Finnish Crash Data Institute) data. The control group consisted of 136 drivers who died in other types of FMVA in 2013. A total of 258 accidents were investigated. RESULTS: The mean age of the 122 drivers in the FSMVA group was 44 (standard deviation 19) years; there were 100 men (82%) and 22 women. The mean age of the 136 control drivers was 45 (standard deviation 19) years; there were 116 men (85%) and 20 women. Short sleep time (<6 h) during the previous night before the accident was the most prominent independent risk factor for FSMVA compared to other FMVA (p < 0.05). None of the other driver-related factors (diseases, blood alcohol level, illegal drugs, body mass index, medications, age, sex) differed significantly between the two groups. CONCLUSION: Short sleep is a major cause of fatal sleepiness-related motor vehicle accidents. Driver health factors such as sleep apnea or acute/chronic diseases as well as use of sedative medications and drugs are known risk factors for FSMVA, but these factors are associated also with other types of accidents. Healthy individuals are at risk for falling asleep while driving if they are sleep deprived. All drivers should be aware of the importance of adequate sleep.

Alcohol policy and fatal alcohol-related crashes in Finland 2000-2016.

OBJECTIVE: The purpose of this study was to explore the relationship between annual alcohol consumption per capita/alcohol price index and the number of alcohol-related fatal motor vehicle accidents (AFMVAs). We were particularly interested in whether a tax reduction in 2004 increased the number of alcohol-related accidents. METHOD: The data consisted of all fatal motor vehicle accidents (FMVAs) during the years 2000-2016 obtained from a database maintained by the Finnish Crash Data Institute (OTI). The data included all fatally injured drivers. We compared the OTI data to official statistics on annual alcohol consumption and the alcohol price index. RESULTS: There were 3,447 fatally injured drivers, of which 25% (n = 869) were intoxicated (blood alcohol concentration [BAC] ≥ 0.05%). After the reduction of the alcohol tax in 2004, the alcohol consumption rose 12.4% from 2003 to 2005 and AFMVAs rose 38%. There was a strong correlation (r = 0.7000, P < .018) between the recorded consumption of alcohol and the number of AFMVAs. There was a strong negative correlation between AFMVAs and the combined (retail + restaurant sales) alcohol price index (r = -0.7863, P = .0005). A linear mixed-effects model showed that a 1-L increase in total alcohol consumption per capita per year increases AFMVAs by 10.6 and a one-unit increase in the price index decreases AFMVAs by 1.8 per year. CONCLUSIONS: The correlation between alcohol consumption and alcohol-related crashes should be considered when making political decisions regarding alcohol price and availability. Any further liberalization of the alcohol policy would likely lead to an increase in alcohol-related fatal motor vehicle accidents. Similar consequences are likely to occur with drugs. Alcohol price policy is an effective way to improve road safety, but other measures taken to prevent FMVAs also seem to reduce the prevalence of AFMVAs.

Airbag deployment-related eye injuries.

OBJECTIVE: We studied the correlation between airbag deployment and eye injuries using 2 different data sets. METHODS: The registry of the Finnish Road Accident (FRA) Investigation Teams was analyzed to study severe head- and eyewear-related injuries. All fatal passenger car or van accidents that occurred during the years 2009-2012 (4 years) were included (n = 734). Cases in which the driver's front airbag was deployed were subjected to analysis (n = 409). To determine the proportion of minor, potentially airbag-related eye injuries, the results were compared to the data for all new eye injury patients (n = 1,151) recorded at the Emergency Clinic of the Helsinki University Eye Hospital (HUEH) during one year, from May 1, 2011, to April 30, 2012. RESULTS: In the FRA data set, the unbelted drivers showed a significantly higher risk of death (odds ratio [OR] = 5.89, 95% confidence interval [CI], 3.33-10.9, P = 2.6E-12) or of sustaining head injuries (OR = 2.50, 95% CI, 1.59-3.97, P = 3.8E-5). Only 4 of the 1,151 HUEH patients were involved in a passenger car accident. In one of the crashes, the airbag operated, and the belted driver received 2 sutured eye lid wounds and showed conjunctival sugillation. No permanent eye injuries were recorded during the follow-up. The calculated annual airbag-related eye injury incidence was less than 1/1,000,000 people, 4/100,000 accidents, and 4/10,000 injured occupants. CONCLUSIONS: Airbag-related eye injuries occurred very rarely in car accidents in cases where the occupant survived and the restraint system was appropriately used. Spectacle use did not appear to increase the risk of eye injury in restrained occupants.

A Prospective 30-Year Follow-Up of ADHD Associated With Perinatal Risks.

OBJECTIVE: Longitudinal follow-up of ADHD suggests a poorer outcome in those affected. Studies extending to 30 years however are rare. We investigated the adult outcome of ADHD associated with perinatal risks (PRs), treated non-pharmacologically. METHOD: A study group of 122 participants (86 men, 36 women) with PR-associated ADHD was followed-up from birth and compared with a control group also prospectively studied. RESULTS: The study group showed more cognitive, motor perception, and learning impairments as well as psychiatric problems at ages 5, 9, and 16. At age 30, the study group reported less education, more involuntary job dismissals and more alcohol abuse. Self-reported ADHD symptoms were still prevalent in adulthood. CONCLUSION: ADHD symptoms persist and impair the long-term educational, occupational, and psychiatric outcome. ADHD in participants with PR appears to follow a course seen in studies of unselected ADHD.

Traffic and Criminal Behavior of Adults with Attention Deficit-Hyperactivity with a Prospective Follow-Up from Birth to the Age of 40 Years.

OBJECTIVE: The purpose of this study was to investigate whether individuals with attention deficit-hyperactivity disorder (ADHD) followed up to age 40 have a higher mortality, more involvement in criminal behavior, increased traffic accidents, and frequency or registered violations against traffic rules or whether they have been more frequently victims to crimes. METHODS: The ADHD cohort (N = 122) born in 1971-1974 was isolated at the age of 9 years from the base cohort of 865 children who had known risk factors at birth and were still alive at the age of 5 years. Ninety-four healthy individuals born during the same years served as control subjects. None of the individuals with ADHD had used psychostimulants before their adolescence. The follow-up data were available from the newborn period until the ages of 5 and 9 years. At the ages of 16 and 30, the data were collected via questionnaire. For this study, the national police registers (last 5 years) were examined for traffic violations, crimes, or being an object of a criminal act when the persons reached the age of 40 years. RESULTS: Ten men and one woman with ADHD but none of the controls had died by the age of 40. Three died of disease-related incidents, and 8 (13%) died of abnormal causes such as suicide (3), traffic accident (2), substance abuse (2), or violence (1). During the follow-up period, individuals with ADHD had been involved in violent behavior or economic criminality more frequently than the control subjects. They were also more commonly victims of criminal acts. No difference was found in traffic citations between those with ADHD and control subjects (at 35-40 years) when all traffic crimes were considered. A difference was not observed in the frequency of traffic accidents. However, there was a significant difference in drunk driving (at the ages of 30 and 35-40) and the number of persons without a driver's license. DISCUSSION: Subjects with ADHD showed an elevated risk of being involved in criminality and had a higher risk of dying before the age of 40 years. The early detection of ADHD in childhood and appropriate treatments and family support may decrease criminality and save both money and human distress.

Peripheral hypertrophic subepithelial corneal degeneration - clinical and histopathological features.

PURPOSE: To refine the diagnostic criteria for peripheral hypertrophic subepithelial corneal degeneration (PHSD) and characterize its clinical phenotype, histopathology and immunohistochemical features. METHODS: Diagnostic criteria were refined on the basis of literature data. Fourteen patients (13 women and one man; median age 52 years, range 33-66) were identified based on these criteria. Keratectomy specimens were evaluated via routine and immunohistochemical stainings. The main outcome measures were symptoms, clinical phenotype, immunological status and histopathologic results. RESULTS: We defined the diagnostic criteria of typical PHSD as elevated circumferential and perilimbal subepithelial fibrosis with focal superficial corneal neovascularization, which were supported by female sex (93%), bilaterality (86%), the centre being in the upper quadrants (81%) and irregular astigmatism of two dioptres or more. The typical symptoms were reduced vision (86%) and the symptoms of ocular surface disease (64%). Light microscopy showed fibrosis with abundant collagen deposition but no inflammation in all patients. An immunohistochemical analysis of nine patients showed uniform staining for vimentin in three distinct types of fibroblasts in variable proportions: keratocyte-like cells that were positive for CD34, myofibroblasts that were positive for smooth muscle actin (SMA) and fibroblasts that were negative for CD34 and SMA. Small numbers of CD68-positive macrophages were also found. CONCLUSIONS: Peripheral hypertrophic subepithelial degeneration is characteristic of middle-aged women, in whom it is typically a bilateral idiopathic degeneration of the cornea associated with ocular surface disease and reduced vision. The fibrotic lesions probably undergo remodelling, inducing changes in corneal contour. A smouldering low-grade inflammation favouring low TGF-ß1 concentrations is postulated as the primary pathological process leading to PHSD.

Peripheral hypertrophic subepithelial corneal degeneration: characterization, treatment and association with human leucocyte antigen genes.

PURPOSE: To evaluate the efficacy of keratectomy in treating irregular astigmatism caused by peripheral hypertrophic subepithelial corneal degeneration (PHSD) and to study the possible underlying immunological risk factors. MATERIALS AND METHODS: Patients (14 eyes) with diagnosed PHSD were treated with superficial keratectomy with or without the assistance of phototherapeutic keratectomy (VisX S4; VisX Inc., Santa Ana, CA, USA). Thirteen patients were subjected to analysis of human leucocyte antigen (HLA) genes, complement C4 gene numbers and total plasma immunoglobulin levels. Immunological risk factors between patients and a control group comprising 150 individuals were compared. RESULTS: The mean preoperative best spectacle corrected visual acuity (BCVA) improved from 0.16 ± 0.22 (LogMAR scale range 0-0.7) to 0.06 ± 0.13 (-0.1-0.4) (p < 0.01). The mean preoperative astigmatism decreased significantly from 3.8 ± 2.1 D (range 1.2-8.2) to 2.1 ± 1.4 (range 0.6-5.0, p = 0.02) based on corneal topography. The HLA-B*44 allele and the ancestral haplotype (AH) 8.1 were found significantly more often in PHSD patients than in controls (both p = 0.03). No differences in the C4 genes were found. CONCLUSIONS: Astigmatism secondary to PHSD can be effectively treated with keratectomy. Peeling of the fibrotic tissue reduced astigmatism and improved visual performance. We suggest that HLA-B*44 allele and AH 8.1 haplotype are immunological factors predisposing to the development of PHSD. The consequent disruption/alteration of the limbal barrier may lead to corneal peripheral fibrous formation inducing astigmatism.

Sudden death at the wheel due to a disease attack.

PURPOSE: To (1) examine the prevalence of fatal disease attacks while driving, (2) evaluate the potential risk of a driver's acute incapacity to drive, (3) compare the risks related to the driver's incapacity to drive with other major risks related to fatal motor vehicle accidents (fMVAs), and (4) assess how these accidents are reported in official statistics. METHODS: The data consist of information from the Finnish Road Accident Investigation Teams (RAITs) on fMVAs in Finland during 2008-2009, in-depth analyses of accidents in the Uusimaa district in 2008-2009, and data from Statistics of Finland (StatFi) concerning accidents in the Uusimaa district. RESULTS: In 2008-2009 as a whole, 488 fMVAs were encountered in Finland, and 73 of these were in Uusimaa. From fMVAs of the whole country, 55 driver deaths (11%) were due to a disease attack and in 27 (6%) of the cases, the driver was presumed to have fallen asleep. In Uusimaa approximately 25 percent (N = 18/73) of deaths at the wheel were caused by a driver's acute disease attack, but only 20 percent were recorded in the official StatFi. Cardiac and neurological diseases were the most common causes of disease attacks while driving. Additionally, disease attacks contributed as a background reason in at least 6/73 (8%) fMVAs. Speeding was found to be involved in approximately 1/3 (N = 190) of all fMVAs; however, in the absence of other risk factors, it was relatively rare (9%; N = 43). CONCLUSION: A disease attack while driving is a relatively common cause of death on the road. Severe injuries may mask the role of an initial disease attack. This hypothesis is supported by the data collected on sleeping and background accidents. Thus, the drivers' disease attacks might have an even broader impact than initially assumed. Monitoring driver health and recognizing comorbidity problems could play a large role in the promotion of road safety. The current method of monitoring the fitness to drive and producing accident statistics should be reevaluated.

Refractive surgery in anisometropic adult patients induce plastic changes in primary visual cortex.

PURPOSE: To prospectively study the effect of refractive surgery in the primary visual cortex of adult anisometropic and isometropic myopic patients. METHODS: Two anisometropic and two isometropic myopic patients were examined with multifocal functional magnetic resonance imaging technique (mffMRI) before refractive surgery and at 3, 6, 9 and 12 months postoperatively. Two controls without refractive surgery were also examined with mffMRI in the beginning and in the end of the study. Anisometropic patients had only their more myopic eye operated to correct the anisometropia. The myopic isometropic patients had their both eyes operated. RESULTS: Operated anisometropic eyes showed 65% reduced amount of active voxels in foveal data at 12 months postoperatively compared with the preoperative situation. In unoperated anisometropic eyes, the corresponding value was 86% and in myopic patients and controls 31% and 1%, respectively. To confirm this finding, the number of activated voxels representing the innermost ring of the stimulus was also calculated, and an exactly similar phenomenon was encountered in the anisometropic patients. Both anisometropic patients improved the best-spectacle-corrected visual acuity in the operated eye after refractive surgery. CONCLUSION: Our results suggest that plastic changes may take place in the primary visual cortex of anisometropic adult patients after refractive surgery.

Long-term outcome of central toxic keratopathy after photorefractive keratectomy.

PURPOSE: To describe long-term postoperative results of 5 eyes that had central toxic keratopathy after photorefractive keratectomy (PRK). METHOD: In a period of 2 months, 74 eyes were subjected to refractive surgery (21 by PRK and 53 by laser in situ keratomileusis) in 2006. Laser ablations were performed with a VISX S4 (VISX, Santa Ana, CA) excimer laser. Five eyes of 5 different patients in the PRK group experienced a corneal stromal thinning associated with a central opacification (haze), hyperopic shift, and central striae in the first postoperative week. Follow-up examinations were at 1 month and at 2, 6, and 12 months and included uncorrected visual acuity, best spectacle-corrected visual acuity (BCVA), manifest refraction, biomicroscopy, and ultrasound pachymetry. At the last follow-up, confocal microscopy was performed in 3 eyes. RESULTS: Corneal thickness measured by ultrasound pachymetry at the first month postoperatively showed an unexpected stromal thinning of 48 ± 39 µm (range, 19-116 µm) compared with the expected postoperative value. At the last postoperative follow-up, corneal thickness had gained 44 ± 22 µm (range, 20-80 µm) compared with the thickness obtained at 1 month. Uncorrected visual acuity, BCVA, haze, and corneal thickness improved in the first postoperative months and stabilized after 6 months. CONCLUSIONS: Central toxic keratopathy is not related to laser in situ keratomileusis (LASIK) only. The presence of 5 cases after PRK in a short period (2 months) associated with a period of simultaneous change of both postoperative medications and postoperative bandage lens practice suggests a link with an unknown pharmacological response leading to stromal dehydration.

[The driver's illness as a cause of traffic accidents]. / Kuljettajan sairaus kuolonkolarien aiheuttajana.

Fatal motor vehicle accidents (fMVAs) as well as accidents involving pedestrians or bicyclists in Uusimaa county in 2008 were reviewed. Of the fMVAs, acute disease attacks while driving caused 26.5% (9/34) of the drivers' deaths. This equalled with the number of alcohol-related fatal accidents. Heart attack was the main cause (7/9 disease attacks). Three bicyclists (3/14; 21%) died for health reasons; two for ventricular fibrillation and one for alcohol intoxication probably combined with cardiac arrhythmia. Diseases served also as background causes for fMVAs. Education of health care personnel on medical conditions and driving should be improved.

Corneal sensitivity in diabetic patients subjected to retinal laser photocoagulation.

PURPOSE: To determine the changes in corneal sensitivity to different stimulus modalities in diabetes mellitus (DM)1 and DM2 patients with retinopathy, and to explore whether argon laser photocoagulation exacerbates sensitivity loss in diabetic patients. METHODS: Corneal sensitivity to different modalities of stimulus was determined in one randomized eye in 52 patients with DM1 (n = 35) or DM2 (n = 17), and in 27 healthy subjects. Medical history was obtained from all the patients, including age, sex, time from DM diagnosis, type of diabetes, time from onset of retinopathy, type of diabetic retinopathy, and type of argon laser treatment. Corneal sensitivity was determined using a gas esthesiometer. Mechanical, chemical, and thermal (heat and cold) stimuli were applied on the central cornea. RESULTS: Sensitivity thresholds to selective mechanical, chemical, and cold stimulation were significantly higher in DM patients compared to controls. Sensitivity threshold to mechanical and chemical stimuli was higher in DM2 than in DM1 patients. In DM1 patients, mechanical threshold increased with time after DM diagnosis. No correlation was found between sensitivity thresholds to chemical or thermal stimulation and the age of the patient, type of retinopathy, or time from its diagnosis. Laser treatment generated a further impairment of corneal sensitivity. CONCLUSIONS: Corneal sensitivity to mechanical, chemical, and thermal stimulation is decreased in DM patients, suggesting that diabetes affects homogeneously the different types of sensory neurons innervating the cornea. Corneal sensitivity appears to be more disturbed in DM2 than in DM1. Laser treatment of DM patients generates a further impairment in corneal sensitivity, probably as the result of physical damage to ciliary nerves.

Long-term follow-up of photorefractive keratectomy for myopia: Comparative study of excimer lasers.

PURPOSE: To compare the long-term results of photorefractive keratectomy (PRK) for low to moderate myopia performed using a broad-beam laser system or a scanning-slit laser system. SETTING: Department of Ophthalmology, University of Helsinki, Helsinki, Finland. DESIGN: Case-control study. METHODS: This follow-up study comprised eyes with myopia (-1.25 to -7.00 diopters [D]) or myopic astigmatism (astigmatism lower than -2.50 D) corrected by PRK using a broad-beam (Visx) or scanning-slit (Nidek) laser. Follow-up included a visit at 3 months and at more than 8 years. The uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refraction were recorded. RESULTS: The broad-beam group comprised 27 eyes and the scanning-slit group, 34 eyes. At the last postoperative follow-up, the UDVA was 0.0 or better in 55% of eyes in the broad-beam group and 65% of eyes in the scanning-slit group. The CDVA was 0.0 or better in all eyes in the broad-beam group and 96% of eyes in the scanning-slit group. Regarding predictability, 48% and 73% of the eyes, respectively, were within ±0.50 D of the intended spherical equivalent refraction. There were no statistically significant differences between the 2 laser groups in any preoperative or postoperative parameter. CONCLUSION: There were no significant differences in UDVA, CDVA, or SE after PRK for low to moderate myopia between the broad-beam laser system and the scanning-slit laser system. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Altered expression of matrix metalloproteinases and their tissue inhibitors as possible contributors to corneal droplet formation in climatic droplet keratopathy.

PURPOSE: Climatic droplet keratopathy (CDK) is an acquired corneal disease characterized by progressive scarring of the cornea. In several corneal diseases, matrix metalloproteinases (MMPs) are upregulated during the degradation of epithelial and stromal tissues. We investigated the levels, degree of activation and molecular forms of MMP-2, MMP-9, MMP-8 and MMP-13 and their tissue inhibitors TIMP-1 and TIMP-2 in tear fluid of patients with CDK. METHODS: Seventeen CDK patients and 10 controls living in Argentine Patagonia received a complete eye examination, and MMPs and TIMP-1/2 were determined by immunofluorometric assay (IFMA), gelatin zymography and quantitative Western immunoblot analysis in tear samples. RESULTS: The MMPs were detected mostly in their latent forms. The levels of MMP-9 and MMP-2 were found to be significantly elevated in CDK patients, whereas latent and active MMP-8 levels were significantly enhanced in controls. There was no significant difference in the level of MMP-13. TIMPs were found as part of complexes, and the TIMP-1 levels were significantly lower in patients than controls. CONCLUSION: Elevated MMP-2 and MMP-9 levels have been implicated in the failure of corneal re-epithelialization, and enhanced MMP-2 and MMP-9 levels in CDK patients suggest that these MMPs may play a role in corneal scarring in CDK. Elevated levels of MMP-8 suggest a defensive role for this MMP in inflammatory reactions associated with recurring corneal traumas. Decreased expression of TIMP-1 in CDK patients suggest deficient antiproteolytic shield likely to render the corneas of CDK patients vulnerable to enhanced MMPs. Overall, these data suggest a mechanistic link between MMPs and TIMP-1 level in cornea and tears with corneal scarring in CDK.