Anna Midelfart

Myopia among medical students in Norway

Abstract. In this study the prevalence of myopia and age at onset among medical students were determined. Of the 140 senior medical students at The Faculty of Medicine, University of Trondheim, Norway, 133 (75 females, 58 males) were examined. Visual acuity was tested and the refractive error was measured using automated refraction and clinical refractive technique. The prevalence of myopia was found to be 50.3% in the right eye (n = 67) without significant difference between female and male students. The refractive state was unrelated to body height. Among the myopic students, the mean equivalent sphere was −2.34 ± 2.01 D in the right eye (range −9.25 D to −0.25 D). A clear relationship was detected between the current amount of myopia and the age at which corrective lenses were first prescribed. However, as much as 43.3% of the myopic students wearing corrective lenses first received these at the age of about 20 years, indicating a relatively high prevalence rate of adult‐onset myopia.

Survey of eye injuries in Norwegian children.

Abstract. A review of the medical records of 238 children younger than 16 years admitted with ocular injury to the University Hospital in Trondheim during a 10‐years period was undertaken to provide information about the causes, circumstances and visual outcome of ocular trauma in young patients. Children with ocular injury represented 14% of all paediatric eye admissions. The majority were boys (77%). The frequency of injuries among boys increased markedly from the age of 8 years, while the frequency was almost the same among girls in all age groups. The most common cause of injury was projectiles (21.5%) followed by sticks, twigs and pencils (10.1%), falls (10.1%), bow and arrows and catapults (9.7%) and balls (8.8%). The most frequent diagnosis was contusion (43%). Perforating eye injuries amounted to 19%. Follow‐up examination showed that 49% of children with eye injuries had some visual deficit, including eighteen children (8%) with visual acuity worse than 0.1. Because most of the eye injuries among children are preventable, more appropriate strategies for the prevention of these should be implemented.

Effect of UVA and UVB Irradiation on the Metabolic Profile of Rabbit Cornea and Lens Analysed by HR-MAS 1H NMR Spectroscopy

Purpose:The aim of the study was to investigate the metabolic profiles of intact rabbit corneas and lenses exposed to UVA and UVB radiation by using high-resolution (HR) magic angle spinning (MAS) 1H nuclear magnetic resonance (NMR) spectroscopy and pattern recognition methods. Methods:Adult albino rabbits were exposed to UVA (366 nm, 0.589 J/cm2) or UVB (312 nm, 1.667 J/cm2) radiation for 8 min, once a day for 5 days. Three days after the last irradiation day, samples of corneas and lenses were dissected. HR-MAS 1H NMR spectroscopy combined with pattern recognition methods (principal component analysis and soft independent modelling of class analogy) and one-way ANOVA were applied to obtain metabolic information from intact corneal and lens tissue. Results: UVB irradiation caused statistically significant metabolic changes in the rabbit corneas. A decrease in metabolites as ascorbate (84%), myo-inositol (59%), hypotaurine (91%) and choline (76%) was observed. Exposure to UVA radiation caused no significant metabolic alteration in this tissue. The metabolic profile of the rabbit lenses showed no detectable changes after UVA or UVB exposure. Conclusions:The combination of HR-MAS 1H NMR spectroscopy and multivariate methods proved effective to analyse intact corneal and lens tissue after exposure to UV radiation of different wavelengths. By avoiding extraction methods and obtaining complete metabolic profiles from one sample, HR-MAS 1H NMR spectroscopy provided important information about metabolic alteration occurring in rabbit corneal and lens tissue after UV exposure.

Detection of different metabolites in the rabbit lens by high resolution 1H NMR spectroscopy.

PURPOSE To investigate the metabolic profile of the rabbit lens using high resolution 1H NMR spectroscopy including two-dimensional shift correlated (COSY) technique. METHODS Perchloric acid extracts of the rabbit lens were analysed with a Bruker AM-500 spectrometer and the metabolites were assigned in the spectra. Some of these were also quantified. RESULTS More than 20 metabolites were detected in the perchloric acid extract of a single lens, including amino acids, nucleotides and other related compounds. Of particular importance is the ability to detect and identify glutathione, myoinositol, scyllo-inositol and taurine. CONCLUSIONS The study demonstrated the potential of 1H NMR spectroscopy for monitoring the metabolic profile of the lens in normal and pathologic conditions.

Visual impairment in stroke patients – a review

Approximately 30% of all stroke patients suffer from post‐stroke visual impairment. Hemianopia is the most common symptom, but also neglect, diplopia, reduced visual acuity, ptosis, anisocoria, and nystagmus are frequent. Partial or complete recovery of visual disorders can occur, but many patients suffer permanent disability. This disability is often less evident than impairment of motor and speech functions, but is negatively correlated with rehabilitation outcome and can lead to a significant reduction in day‐to‐day functioning. To be visually impaired after stroke reduces quality of life and causes social isolation because of difficulties in navigating/orientating in the surroundings. A thorough diagnosis including targeted examination and later follow‐up with eye examination and perimetry is essential in order to establish the extent of the visual impairment and to select the best rehabilitation strategy. Patients seem to profit from visual rehabilitation focused on coping strategies.

Ocular parameters in elderly in Norway

Abstract. A retrospective review of medical records of 434 patients (mean age 76.2 ± 10.1 years) undergoing cataract surgery was performed to detect possible sex differences for several ocular parameters and their change with age. More women were operated for cataract than men by a 2:1 ratio. Their age was not significantly different. Women had higher intraocular pressure (15.4 ± 3.5 mmHg), shorter axial length (22.98 ± 1.31 mm) and steeper cornea (43.64 ± 1.61D) than men (14.7 ± 3.6 mmHg, 23.33 ± 0.97 mm and 42.88 ± 1.52D, respectively). For both sexes, a negative correlation between the corneal refraction and axial length was revealed. For women, a trend towards shorter eyes in the higher age groups was found. Among those older than 80 years, stronger intraocular lenses were implanted in women than in men. Based on these results, more attention should be paid to the differences between women and men regarding ocular parameters in the elderly.

Epidemiology and Heritability of Astigmatism in Norwegian Twins: An Analysis of Self-Reported Data

Purpose: To describe the occurrence and heritability of astigmatism in a population-based sample of Norwegian twins. Methods: Self-reported history of astigmatism based on questionnaire responses was used to estimate the prevalence and incidence rates of astigmatism from birth through 31 years in 8,045 twins. Kaplan-Meier analysis and log-binomial regression were used to study the conditional and relative risk of astigmatism in twin pairs by sex and zygosity. Tetrachoric correlations and structural equation models were applied to estimate the genetic and environmental sources of variations in liability for astigmatism. Results: Altogether 21.1% of males and 29.3% of females (p < 0.001) reported a positive history of astigmatism. Estimated incidence rates peaked in both sexes in the group aged 16–19 years and then decreased. Both conditional and relative risks of developing astigmatism were considerably higher in monozygotic than in dizygotic twins if a cotwin reported a positive history of astigmatism. The best-fitting biometrical model suggested that additive genetic, dominant genetic, and individual environmental effects explained 9% (95% CI: 0–40), 54% (95% CI: 20–69), and 38% (95% CI: 31–45) of the variation in the liability to astigmatism, respectively. No differences in heritability of astigmatism between the genders were found. Conclusions: The prevalence of self-reported astigmatism in twins is comparable with previous findings from Norway. Our results suggest considerable genetic contribution to the development of astigmatism in young adult Norwegian twins mainly due to dominant genetic effects, which are similar in both males and females.

Metabolic Analysis of the Rabbit Cornea by Proton Nuclear Magnetic Resonance Spectroscopy

Perchloric acid extracts of the rabbit cornea were analyzed by high-resolution 1H NMR spectroscopy, including the two-dimensional shift-correlated (COSY) technique. Numerous metabolites including leucine/isoleucine, 3-hydroxybutyrate, valine, lactate, alanine, lysine, acetate, glutamate, creatine/phosphocreatine, taurine, glycine, inositol, glucose, tyrosine, phenylalanine, histidine, adenosine and formate have been simultaneously detected and identified in the NMR spectra. Concentrations of some of these were also determined. Of particular importance are the detection and identification of hypotaurine in the corneal tissue. Hypotaurine is a precursor of the synthesis of taurine and may act as an antioxidant. Moreover, the presence of choline, a precursor for acetylcholine, was established. This novel metabolite profile of the cornea obtained by high-resolution 1H NMR spectroscopy may be of value in the study of pathologic and toxic disorders.

High-resolution 1H NMR spectroscopy of aqueous humour from rabbits

Abstract⊎ Background: Detection of different substances in aqueous humour is important for evaluation of the disorders affecting the eye. The purpose of the present study was to apply highresolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy for extensive characterisation of the metabolites in the aqueous humour from rabbits. ⊎ Methods: High-resolution 1H NMR spectroscopy, including two-dimensional shift correlated (COSY) technique, was performed on aqueous humour from rabbits. ⊎ Results: More than 20 metabolites were simultaneously detected and identified in high-resolution 1H NMR spectra of aqueous humour from rabbits. Some of these were also quantified. ⊎ Conclusion: High-resolution 1H NMR spectroscopy is a valuable method for simultaneous detection of many different metabolites in aqueous humour.

Retinal nerve fibre layer attenuation: clinical indicator for vigabatrin toxicity.

Purpose:  To investigate whether persistent visual field defects among patients exposed once to the antiepileptic drug vigabatrin (VGB) were associated with peripapillary retinal nerve fibre layer thickness (RNFLT) attenuation.