Biomedical subjects

H Alanko

Publications and source records attributed to H Alanko.

8 recordsLinked to original sources

PubMed2000

Digital imaging and microtexture analysis of the nerve fiber layer.

PURPOSE: To describe the design of a digital retinal nerve fiber layer (RNFL) imaging techniques and present a new approach to measure the differences in RNFL patterns. METHODS: A digital camera body is connected to a wide-angle camera to obtain images of the RNFL, which are displayed in workstations throughout the clinic. In the on-line archive, images in Joint Photographics Experts Group (JPEG) format (100 KB per frame) are used. The hypothesis that changes in RNFL structure can be seen as changes in the microtexture of digital images was tested using an information theoretical approach (Kullback Information Distance, KID). A large KID value indicates a large difference, and a small KID value indicates a small difference in microtexture between the two regions. The material of this pilot study consists of 9 patients with glaucoma, 8 patients with ocular hypertension, and 7 normal subjects. RESULTS: The median KID value in the glaucoma group was 3.5, compared with the median KID values of 0.6 in the control groups. Although a trend could be seen in the measured values, because of a small sample size, the differences were not statistically significant. Five of 24 (21%) KID values overlapped between the glaucomatous group and the other two groups. CONCLUSION: Although digital imaging produces good quality RNFL images, further research is needed to establish minimum accepted specifications for digital imaging. In this pilot study, only the microtexture of the RNFL was measured in digital images. In the future, the approach can be expanded to include also properties of macrotexture and full color palette.

Exfoliation Syndrome↗

PubMed1997

Fluorometry of the crystalline lens for correcting blue-on-yellow perimetry results.

PURPOSE: Optical and neural sources of short wavelength sensitivity should be separated in the assessment of the results of blue-on-yellow (B/Y) perimetry. It has been shown previously that lens autofluorescence is related directly to lens yellowing and age. The aim of this study was to find out if B/Y perimetry results can be better corrected by using lens fluorometry than by age. METHODS: The authors evaluated one randomly chosen eye of 40 normal subjects and 39 age-matched patients with ocular hypertension and different stages of glaucoma. The authors obtained the mean sensitivity (MS) of the 24-2 B/Y visual fields with a Humphrey perimeter and determined the lens transmission index (LTI) from the ratio between posterior and anterior autofluorescence peaks measured with their fluorometer. A multiple regression analysis was used to evaluate the variability of the B/Y MS by age and LTI in normal subjects. RESULTS: The authors found a statistically highly significant linear correlation of B/Y MS to LTI in healthy subjects (R = 0.83; P < 0.0001). The 95% prediction interval of the normal subjects was determined. The majority of the MS values of the ocular hypertensives were inside the prediction limits, whereas approximately half of the patients (4 of 9) with early glaucoma and the majority of patients (14 of 15) with moderate and advanced glaucoma were below the prediction interval. The residual standard deviation of the B/Y MS with age alone was larger than that with LTI alone in the model (3.66 dB and 3.22 dB, respectively). CONCLUSIONS: The interindividual variation of the lens transmission properties increases with age. The reference level for correcting B/Y perimetry results can be determined more precisely using fluorometry of the lens than with age alone.

Adult↗

PubMed1981

Clinical and neurophysiological findings in heterozygotes for nonketotic hyperglycinemia.

Heterozygotes for nonketotic hyperglycinemia (NKH), a disorder of glycine degradation, have a slightly abnormal metabolism of glycine. As the severe neurological symptoms which are characteristic for the homozygotes are at least partially due to a disturbance of glycine function as a neurotransmitter, minor neuronal dysfunctions might be expected also in heterozygotes. Although their general health was within normal limits in these 13 heterozygotes, slight neurological symptoms and signs were observed. Neurophysiological investigations revealed disturbance of the vestibular function in six subjects, preponderance of beta-wave activity in five, subnormal amplitude of a-wave, and shortening of implicit time of the first oscillatory potential (OPI) in the retinography. Functioning of peripheral nerves appeared normal in measurements of motor conduction velocity, distal latency and amplitude of muscle response. These minor dysfunctions of the central nervous system may well be due to a slightly abnormal degradation of glycine in heterozygotes for nonketotic hyperglycinemia.

Adult↗

PubMed1981

Pars plana vitrectomy in the management of intraocular inflammation.

To evaluate the role of pars plana vitrectomy in the management of intraocular inflammation with dense vitreous opacification, vitrectomy was performed in 14 patients with chronic uveitis, 6 eyes with retinal periphlebitis, and in 8 cases of endophthalmitis. Visual acuity improved in 21 eyes, remained unchanged in 3, and deteriorated in 4 cases (follow-up period 2 months to 3 years). Pre-existing retinal damage such as cystoid macular oedema or degeneration restricted final visual acuity. In most eyes inflammation (aqueous flare and cells) diminished, except in hypotonic eyes with chronic iridocyclitis, which also gained little in vision. The results indicate that vitrectomy is valuable in the treatment of chronic uveitis with vitreous opacification due to cellular invasion and membrane formation, in periphlebitis with vitreous hemorrhages, and in endophthalmitis.

Adult↗

PubMed1980

Electronic subtraction method for ophthalmic photography.

A commercial electronic subtraction unit originally intended for the study of roentgenograms was used to produce subtraction pictures of fundus fluorescein angiographies. No modifications were needed to make good quality subtraction pictures. The method is fast and inexpensive in contrast to previously described photographic methods. Certain limitations of the present equipment are discussed as well as some possibilities for further development of the apparatus. The method is especially suitable for studies on dynamic processes in the eye and it should prove valuable in the long-term follow-up of chronic diseases such as glaucoma and diabetic retinopathy.

Adult↗

PubMed1980

Demonstration of glaucomatous optic disc changes by electronic subtraction.

We describe a new method, the electronic subtraction, for objective two-dimensional detection, demonstration and recording of glaucomatous optic disc changes. Siemens subtraction unit M 707 A, based on a double videochain and originally developed for the study of roentgenograms, was used. The results show that this technique is useful in demonstrating the progressive damage of neural tissue of the disc and associated alterations in the course of the vessels. Further development of the electronic subtraction method for glaucomatous optic disc evaluation is discussed.

Aged↗

PubMed1977

Nephropathia epidemica. The Scandinavian form of hemorrhagic fever with renal syndrome.

We report epidemiologic, clinical, laboratory, and biopsy findings in 14 cases of nephropathia epidemica. The patients were between 19 and 49 years of age. The onset of the disease was characterized by high fever, nausea, headache, backache, abdominal pain, proteinuria, oliguria, hematuria, and uremia. The symptoms subsided rapidly during the polyuria phase, which followed the oliguria stage. Because of renal failure, hemodialysis was required in eight cases. Edema of eyelids, conjunctival injection and hemorrhages, transitory myopia, and acute glaucoma were the most common eye abnormalities. Renal biopsy specimens showed glomerular changes, with mild swelling of the epithelial cells of Bowman's capsule, thickening of the basement membrane of glomerular capillaries, glomerular adhesions, inflammatory cell infiltration, leukocytoclasis and hemorrhages in the interstitium, and eosinophilic hyaline degeneration and vacuolization of the epithelial cells of the proximal tubuli.

Acute Disease↗

PubMed1975

Uveitis: report of a 10-year survey in Northern Finland.

In order to determine the distribution of etiologic and diagnostic categories of uveitis at the Oulu University Eye Hospital, 653 patients with uveitis treated during the years 1964-1974 were reviewed. Of the 653 patients, 321 were men and 332 women; 547 had anterior, 64 posterior and 42 generalzied uveitis; 524 unilateral and 129 bilateral; 570 acute and 83 chronic; and 446 single and 207 recurrent. The etiologic factors were distributed into rheumatoid (7.2%), streptococcal (4.1%), tuberculosis (3.7%), toxoplasmosis (3.3%), varicella-zoster (1.7%), sarcoidosis (1.4%), staphylococcal (1.1%), leptospirosis (0.6%), lymphatic leucemia (0.5%), herpes simplex (0.5%), yersinosis (0.1%) and undetermined cases (75.8%). There were no cases of syphilis. Most of the cases in this series were anterior and acute uveitis occurring mainly in the age group 20-59 years.

Adolescent↗