Biomedical subjects

F Jónasson

Publications and source records attributed to F Jónasson.

10 recordsLinked to original sources

PubMed1998

Helicoidal peripapillary chorioretinal degeneration: electrophysiology and psychophysics in 17 patients.

AIMS: To characterise retinal function using electrophysiological and psychophysical tests in 17 patients with helicoidal peripapillary chorioretinal degeneration. METHODS: The electroretinogram (ERG) was recorded using gold foil corneal electrodes. The electro-oculogram (EOG) was recorded using a standard protocol. Dark adaptometry was recorded with an SST-1 dark adaptometer and colour vision assessed with Ishihara plates and Farnsworth D-15. RESULTS: All subjects had a recordable ERG. The amplitudes and implicit times of the a- and b-waves were within normal limits at all luminances in five subjects (age 21-70 years, mean 40 years). The ERG of six (age 26-55 years, mean 40.7 years) had subnormal amplitudes at all luminances, but normal implicit times, and six (age 38-81 years, mean 60.7 years) had abnormal ERGs with marked reduction of a- and b-waves, and delayed implicit times of the b-wave. The implicit times of the a-wave were normal in all subjects. A reduction in the b/a wave ratios was not found, nor was there selective loss of scotopic, mixed rod/cone, or cone responses. The light/dark ratio of the EOG was subnormal (150-185%) or abnormal (below 150%) in all but three subjects. Two patients with normal EOG showed normal ERGs in both eyes, but one had subnormal ERGs in both eyes. The scotopic sensitivity was normal in all subjects and dark adaptation showed a normal time course. Colour vision was normal in all patients. CONCLUSION: The results suggest that in most cases the function of the retinal pigment epithelium is affected by this disease before any changes in the function of the sensory retina are detectable by our methods, and that retinal dysfunction is focal rather than diffuse.

Adaptation, Ocular↗

PubMed1997

Active prevention in diabetic eye disease. A 4-year follow-up.

Ten years after the foundation of a national diabetic eye screening program in 1980, we have established a low prevalence of blindness and partial sight in type 1 and type 2 diabetics in Iceland. We ask whether the screening program is also associated with a low incidence of blindness in diabetics. We now report the results of a prospective study on the 4-year incidence of diabetic retinopathy and visual impairment in type 1 diabetics with age at onset less than 30 years. Out of 205 patients participating at baseline, 175 patients (85.4%) participated over the full 4-year period. Patients were examined annually and received laser treatment according to Diabetic- and Early Treatment Diabetic Retinopathy Study criteria. The 4-year incidence of any retinopathy was 38.1%, of proliferative retinopathy 6.6%, and of macular edema 3.4%. Out of 174 patients, 7.4% showed improvement in visual acuity of 2 Snellen lines while 2.5% experienced worsening of visual acuity of 2 Snellen lines during the 4-year period. No diabetic suffered more than 2 lines deterioration of vision and none became legally blind. The incidence of retinopathy in Icelandic type 1 diabetics participating in our annual eye screening program is low and the visual acuity stable. Our results suggest that visual impairment in diabetics can be prevented with active regular screening and standard laser therapy.

Adolescent↗

PubMed1995

Screening for diabetic retinopathy. Initiation and frequency.

A screening program for diabetic eye disease was established in Iceland in 1980. Diabetics involved in the screening program have a low prevalence of blindness, 1% in type 1 and 1.6% in type 2. We examined ways to make the screening program more efficient by identifying subgroups at low risk of developing eye disease that require treatment and therefore need less frequent screening. We studied whether diabetic eye disease screening programs may be trimmed by excluding children and examining diabetics without retinopathy biannually. Our results indicate that diabetic children under the age of 12 years do not need regular screening for eye disease. Biannual examinations seem to suffice in type 1 and 2 diabetic patients without retinopathy. However, in a setting where the eye clinic is located apart from the diabetes clinics, biannual examinations present practical problems which could result in a less effective screening for diabetic eye disease.

Adolescent↗

PubMed1994

Systematic screening for diabetic eye disease in insulin dependent diabetes.

Under a national program established in 1980, the eyes of approximately 90% of the insulin dependent diabetic patients in Iceland have undergone annual eye examination and fundus photography. Laser treatment was given for proliferative retinopathy or diabetic macular edema according to Diabetic Retinopathy Study and Early Treatment Diabetic Retinopathy Study criteria. We report on 205 insulin-taking patients whose age at diagnosis was less than 30 years of age. Retinopathy was present in 106 (52%) patients and proliferative retinopathy in 26 (13%). 196 patients (96%) had visual acuity equal or better than 6/12 in their better eye, 6 patients (3%) with 6/18-6/48 in their better eye, and 2 patients (1%) equal or worse than 6/60 in their better eye.

Adolescent↗

PubMed1994

Screening for eye disease in type 2 diabetes mellitus.

A screening program for diabetic eye disease was established in Iceland in 1980. Approximately 90% of the insulin dependent patients in Iceland undergo annual eye examination and fundus photography and about a fifth of the type 2 diabetic patients. We report on 245 diabetic patients with type 2 diabetes. Any diabetic retinopathy was present in 100 patients (41%), proliferative retinopathy had been present in 17 (7%) and 24 (10%) had clinically significant diabetic macular edema. Two-hundred and twenty-four patients (91%) had visual acuity equal or better than 6/12 in their better eye, 17 patients (7%) with 6/18-6/36 in their better eye, and 4 patients (1.6%) equal or worse than 6/60 in their better eye.

Adolescent↗

PubMed1993

Retinal vasoconstriction after laser treatment for diabetic macular edema.

The diameter of retinal arterioles, venules, and their macular branches was measured before and after macular laser photocoagulation in one eye each of six men and eight women with diabetic macular edema. The macular arteriolar branches constricted 20.2% (P < .001) and the venular branches constricted 13.8% (P < .001). This autoregulatory vasoconstriction results from the improved retinal oxygenation caused by the laser treatment. By extrapolating the principles of tissue edema formation in general, we hypothesized how macular laser treatment affects diabetic macular edema. Starling's law predicts that (laser-induced) vasoconstriction and reduced intravascular hydrostatic pressure should reduce edema formation in any tissue, including the retina.

Adult↗

PubMed1991

Exudative retinal detachment in familial pulmonary hypertension.

In a family with pulmonary hypertension, one woman developed bilateral exudative retinal detachments and her daughter developed a unilateral exudative retinal detachment during pregnancy. Treatment with Acetazolamide provided quick recovery in the bilateral case, whereas the unilateral exudative detachment recovered without treatment after delivery. Exudative retinal detachments have not previously been associated with pulmonary hypertension.

Acetazolamide↗

PubMed1983

Prognostic factors and retinopathy in type 1 diabetics in Iceland.

Prognostic factors, particularly those related to metabolic control, were analysed individually over a period of 12 months prior to fundus photography in 149 type 1 (insulin-dependent, ketosis-prone) diabetics in Iceland. Patients without retinopathy in their first 20 years of diabetes visited the Diabetic Clinic significantly more frequently than those with retinopathy (p less than 0.05). Mean blood sugar values and mean per cent body weight did not differ between patients with or without retinopathy. Few between patients with or without retinopathy. Few patients were obese. In patients with 5-9 years' duration of diabetes, retinopathy was first seen after 7.7 +/- 0.3 years (mean +/- SEM). Those with retinopathy were significantly older at the time of the diagnosis of diabetes than those without eye lesions (p less than 0.025), a tendency also noted in those with 10-19 years' duration (p less than 0.10). Conversely, patients without retinopathy after diabetes for 20 years or more were significantly older at the time of diagnosis (p less than 0.02). They used significantly less insulin daily than those with retinal lesions (p less than 0.005) and 70% were females. Subsequently, a significant (p less than 0.047) male excess was found to characterize a group of patients with proliferative retinopathy.

Adolescent↗

PubMed1982

Prevalence of retinopathy and proteinuria in type 1 diabetics in Iceland.

The prevalence of retinopathy and proteinuria was assessed in 212 and 230 type 1 diabetics in Iceland respectively. They represent 78% and 84% of all such patients identified in the country. Retinopathy was present in 33.5%, background lesions only in 27.4% and more severe retinopathy in 6.1%. After 5-9 years of diabetes (mean 6.9) the prevalence of retinopathy was 18.8%, including 2.1% proliferative, and rose to 76.7% after 20 years or more of diabetes (mean 26.7), including 16.2% in the proliferative stage. Blindness was found in 2.4% of the patients. Diabetics diagnosed at the age of 0-19 years had a lower prevalence of retinopathy during their first 20 years of diabetes than those diagnosed later in life (p less than 0.05). Proteinuria was present in 14%, intermittent in 10% and continuous in 4%. After 10 years or more of diabetes (mean 19.3) the prevalence of intermittent and continuous proteinuria was 13.0% and 8.3%, respectively.

Adolescent↗

PubMed1978

Orbital plasma cell tumours.

This paper reports two cases of orbital plasma cell tumours, one initially presenting as a localized lesion, but later developing dissemination and proving fatal within 7 months; the other presenting initially as a disseminated disease and apparently cured from that particular disease within 1 year, both on equivalent treatments. The importance of investigations for general disease (for therapeutic reasons) is emphasized as well as possibility of renal involvement and the unpredictability of the clinical course.

Acute Kidney Injury↗