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Biomedical subjects

A Tuulonen

Publications and source records attributed to A Tuulonen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Correlation of blue-on-yellow visual fields with scanning confocal laser optic disc measurements.

PURPOSE: Visual field defects and changes in the optic nerve head are signs of glaucoma. It has been shown that blue-on-yellow (B-Y) perimetry can reveal visual field defects earlier and shows them larger than does white-on-white (W-W) perimetry. The Heidelberg retina tomograph (HRT) can produce three-dimensional images of the optic disc. The aim of this study was to find out how B-Y perimetry results correlate with optic disc parameters in comparison with W-W perimetry results. METHODS: One randomly chosen eye was evaluated in each of 40 normal subjects and 37 patients with ocular hypertension and different stages of glaucoma. B-Y and W-W visual fields (program 30-2) were obtained with a Humphrey perimeter. B-Y perimetry results were adjusted for the patient's age and lens transmission index measured with a lens fluorometer. The B-Y visual field adjusted mean deviation (MD) was calculated as the difference between the measured and expected mean sensitivity values, predicted by the regression model fitted in normal subjects. The HRT with software version 1.11 was used to acquire and evaluate topographic measurements of the optic disc. RESULTS: The cup shape measure showed strongest correlation with the MD of both the B-Y and W-W visual fields. The multiple correlation coefficients from quadratic regression were 0.65 for both visual fields. Except for peripapillary retinal nerve fiber layer measurements, the statistically significant correlations of the B-Y visual field indexes with other HRT parameters were equal to or better than those of W-W perimetry. CONCLUSIONS: B-Y perimetry MDs are well correlated with optic nerve head parameters measured with the HRT. In early stages of glaucoma, most HRT variables were better correlated with the B-Y MD than with the W-W MD.

Adult↗
PubMed1996

Interobserver variation in the measurements of peripapillary atrophy in glaucoma.

PURPOSE: The purpose of this retrospective study is to compare the measurements of intrapapillary and peripapillary parameters between two observers and test the usefulness of measuring different types of crescents. METHODS: Optic disc photographs of 23 eyes of 23 patients with glaucoma and 23 age-matched normal eyes were measured in Oulu and in Erlangen using manual planimetric techniques. The authors measured the following magnification corrected intrapapillary and peripapillary areas: optic disc, neuroretinal rim, cup: disc area ratio, scleral ring, central (zone beta), and peripheral peripapillary atrophy (zone alpha). Twenty-one patients with glaucoma had a follow-up of 3.2 years (range, 1.1-4.7 years), and follow-up for 19 control eyes was 3.7 years (range, 2.5-5.9 years). The measurements were performed in a masked fashion for the diagnosis and temporal sequence of the photographs. RESULTS: Central peripapillary atrophy (zone beta) was statistically significantly largest in primary open-angle glaucoma in both centers (Oulu, P=0.003; Erlangen, P=0.004), whereas normal and exfoliative eyes did not differ significantly from each other. The results for peripheral peripapillary atrophy (zone alpha) and scleral ring were less consistent. Despite statistically significant interobserver correlations ranging from r=0.30 (scleral ring area; P=0.0472) to r=0.97 (optic disc area; P=0.0001), the means of all parameters, except for zone alpha and beta, differed statistically significantly between the two observers. CONCLUSIONS: The central peripapillary atrophy, or zone beta, is the most reproducible parameter when measuring peripapillary atrophy in glaucoma. Nonetheless, its measurement is of limited usefulness in the recognition of glaucoma or progression of glaucomatous nerve damage.

Adult↗
PubMed1996

Polarimetry of the retinal nerve fiber layer.

Retinal nerve fiber layer (RNFL) examination is a useful tool in the diagnosis and follow-up of glaucoma. Because the clinical techniques to date have been subjective, there is a definitive need to develop instruments that are capable of making accurate and reproducible measurements of the RNFL. Introduction of new quantitative methods, such as confocal scanning laser ophthalmoscopy and optical coherence tomography raises high expectations in clinical practice. In the Nerve Fiber Analyzer (Laser Diagnostic Technologies, San Diego, CA) the measurement technique is based on the assumption that the RNFL has birefringent properties. The change in the polarization state, called retardation, can be quantified by determining the phase shift between polarization of light returning from the eye with the known state of polarization of the illuminating laser beam. The retardation shows a typical double-hump pattern of the RNFL thickness around the optic disk. After elimination of artifacts produced by the anterior segments of the eye, the retardation is related linearly to histopathologic thickness measurements of the RNFL in monkey and human eyes. Prior to large-scale implementation of this technique into clinical practice, however, several questions need to be answered.

Animals↗
PubMed1996

Collagen synthesis activity in the aqueous humour of eyes with glaucoma surgery: a pilot study.

AIMS: The purpose of this pilot study was to test whether the rate of collagen synthesis is measurable in the aqueous humour samples in reoperated and previously unoperated eyes. METHODS: The material consisted of 28 eyes of 27 patients, aged 5 to 82 years, in whom aqueous humour samples were obtained during eye surgery. Fifteen patients had no history of previous eye surgery (control group) while 12 patients were re-operated (study group). The carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were measured by specific immunoassays in the aqueous humour samples. RESULTS: The mean concentration of PIIINP in the study group (8.4 (SD 12.5) micrograms/l) was statistically significantly larger than that of the control group (0.4 (0.4) micrograms/l) (p < 0.0037). The respective values for PICP were 98.8 (SD 177.7) micrograms/l in the study group and 0.7 (SD 2.8) micrograms/l in the control group (p < 0.0005). The eyes in the study group which were re-operated within 1 year showed values increased 20-fold compared with the eyes in the control group and those eyes in the study group which had had their previous operation more than a year ago. In three eyes aqueous humour samples were also obtained from the encapsulated Molteno bleb and showed values increased 12-fold compared with those from the anterior chamber. CONCLUSIONS: PICP and PIIINP immunoassays are suitable for measuring the rate of collagen synthesis in the aqueous humour and may be useful in studies on pharmacological modulation of wound healing in glaucoma surgery.

Adolescent↗
PubMed1993

Intraocular pressure-reducing effect of PhXA41 in patients with increased eye pressure. A one-month study.

PURPOSE: To establish the dose-response relationship for the effect on intraocular pressure (IOP) and side effects during long-term treatment of patients with ocular hypertension with the prostaglandin F2 alpha (PGF2 alpha) analog PhXA41. METHODS: A three-center, randomized, double-masked study where IOP, conjunctival hyperemia, and ocular irritation were followed during a 1-month twice-daily treatment with placebo or 35, 60, or 115 micrograms/ml PhXA41 in 60 patients with ocular hypertension, primary open-angle glaucoma, or capsular glaucoma. RESULTS: The three concentrations of PhXA41 reduced the average IOP between 31% and 38% during the second day of treatment, with only a weak dose-response relationship. The initial effect declined somewhat during the first 2 weeks of treatment but then remained at the same level for the rest of the study, with a pressure reduction of approximately 20% for all three concentrations. On the second day of treatment, mild conjunctival hyperemia could be observed in most treated patients. Nineteen of 45 PhXA41-treated patients, compared with 2 of 15 placebo-treated patients, reported to have mild to moderate ocular irritation. These side effects became less pronounced during the study, and at the end there was little difference in the degree of conjunctival hyperemia between placebo- and drug-treated eyes, and no drug-related ocular irritation was reported with the two lowest concentrations of PhXA41. CONCLUSIONS: It is confirmed that the PGF2 alpha analog PhXA41 is a major improvement with respect to the effect-side effect relationship and that it may become a valuable new agent for the treatment of glaucoma.

Adult↗
PubMed1993

Nerve fiber layer defects with normal visual fields. Do normal optic disc and normal visual field indicate absence of glaucomatous abnormality?

PURPOSE: When the optic disc has normal appearance with no abnormalities in routine automated perimetry, the subject is not considered to have glaucoma. The purpose of this study is to show how such patients may have localized retinal nerve fiber layer defects with corresponding functional abnormality. METHODS: The authors selected eight eyes of eight patients who had a localized retinal nerve fiber layer defect extending within a few degrees from fovea but in whom the optic disc appearance and Humphrey 30-2 visual fields were normal. Of the eight patients, three had positive family history of glaucoma, two had suspected retinal nerve fiber layer abnormality in routine eye examination, two had increased intraocular pressure (IOP), and one had advanced low-tension glaucoma in one eye with a normal fellow eye. The authors examined the central 10 degrees visual field with 1 degree resolution using Humphrey perimeter and the Ring and Centring programs of the high-pass resolution perimeter. RESULTS: A central field defect corresponding to retinal nerve fiber layer defect was found in six of eight patients: in both 10 degrees Humphrey field and Centring programs (2 eyes), in Humphrey only (2 eyes), and in Centring only (2 eyes). CONCLUSION: The results indicate that retinal nerve fiber layer photographs are helpful in diagnosing glaucoma because early glaucomatous abnormalities cannot be excluded without nerve fiber layer photography. Currently available routine perimetric examination programs do not always detect very early functional damage.

Aged↗
PubMed1993

Autofluorescence in cataractous human lens and its relationship to light scatter.

The autofluorescence profile of the lens was measured from 84 eyes of 84 patients with cortical, nuclear, posterior subcapsular, or mixed lens opacities. Measurements were performed with a fluorometer in the blue-green autofluorescence range (495 nm/520 nm). The mean maximum autofluorescence value differed in every cataract group statistically significantly from that of the age matched controls (p < or = 0.0058). The highest autofluorescence values were measured in nuclear and mixed cataract groups (p < 0.0001) with high and narrow autofluorescence profile. In cortical cataracts the curve was low and flattened and the mean maximum autofluorescence value was lower than in the control eyes (p < 0.0001). The maximum autofluorescence was related to lens coloration as well as to visual acuity only in nuclear cataract. The regression between maximum autofluorescence and light scatter was statistically significant only in the nuclear cataract group (p = 0.0004). Since the autofluorescence profiles differed not only in height but also in width between the cataract groups, various width/maximum autofluorescence ratios were measured. In nuclear and mixed cataract groups the ratio 75% width/maximum autofluorescence was statistically significantly lower than in other groups (p < 0.0001). In cortical cataracts the ratio (50% width - 75% width)/maximum autofluorescence was statistically significantly higher than in other groups (p < 0.0001).

Adult↗
PubMed1992

Rate and pattern of neuroretinal rim area decrease in ocular hypertension and glaucoma.

The neuroretinal rim areas of 123 eyes (from five normal subjects, 75 patients with ocular hypertension, and 43 patients with glaucoma) were measured to determine the rate and pattern of rim area change during 5 to 15 years (mean, 10 years) of follow-up. Fifty-seven percent of the patients with ocular hypertension and 79% of those with glaucoma showed a statistically significant slope of rim area decrease, a high rate of loss being associated with a high initial rim area. Ninety percent of the variation of rim area loss was accounted for by variables other than the ones measured herein, however (age, disc area, initial rim area, and intraocular pressure). The yearly loss of rim area was 0.23% of the initial area in normal subjects, 0.47% and 2.75% in the patients with stable and deteriorating ocular hypertension, respectively, and 3.47% in the patients with deteriorating glaucoma. The pattern of rim area change was linear in 49% of the patients with a statistically significant rim area decrease, episodic in 22%, and curvilinear in 29%.

Adult↗
PubMed1992

Optic disc size in exfoliative, primary open angle, and low-tension glaucoma.

We examined the magnification-corrected optic disc size in 54 patients with exfoliative glaucoma, 61 patients with primary open angle glaucoma, and 50 patients with low-tension glaucoma. The mean optic disc area in low-tension glaucoma was statistically significantly larger than that in primary open angle and exfoliative glaucoma. The mean values of eyes with primary open angle and exfoliative glaucoma did not differ significantly from each other. Frequency distribution of the optic disc size showed, however, that all three diagnostic groups differed significantly from each other. Small discs were more frequent in eyes with exfoliative glaucoma, and large discs were more frequent in eyes with low-tension glaucoma. In primary open angle glaucoma, small and large optic discs were found equally frequently. It is possible that in some eyes large optic discs are vulnerable to even low intraocular pressures due to qualitative properties of the extracellular matrix.

Aged↗
PubMed1992

The follow-up of patients screened for glaucoma with non-mydriatic fundus photography.

In order to evaluate the value of photographic screening in predicting progressive glaucomatous damage, we re-examined 26 subjects 5 years after the initial screening. Of the 26 patients 16 had typical glaucomatous optic disc and visual field abnormalities (n = 7), retinal nerve layer damage (n = 6), or other risk factors of glaucoma (n = 3). In 10 of 26 patients suspected of having glaucoma, no abnormalities were initially confirmed. Of the 16 eyes with initially abnormal findings, 10 (63%) showed progressive changes during the 5-year follow-up period. The 10 initially suspected cases have remained healthy throughout the follow-up, giving a false positive rate of 5.5%. The results of this study indicate that it is possible to identify correctly patients with progressive glaucomatous changes with a non-mydriatic fundus camera.

Female↗
PubMed1992

Neuroretinal rim area measurements by configuration and by pallor in ocular hypertension and glaucoma.

PURPOSE: The purpose of this study is to examine the differences between measurements of neuroretinal rim area of the optic disc defined by configuration and by pallor. METHODS: One hundred seventy-one patients were studied (59 with glaucoma, 96 ocular hypertensive patients, and 16 controls). The magnification-corrected neuroretinal rim area was measured from black-and-white stereoscopic paper prints. The central area of pallor was measured using computer-assisted image analysis techniques. The percentage of central area of pallor was converted into mm2, and an estimate of neuroretinal rim area defined by color was calculated. RESULTS: The correlation between the measurements of neuroretinal rim area by configuration and by pallor was statistically highly significant (r = 0.89, P less than 0.0001). No consistent differences between measurements were found in different diagnostic groups, or in different stages or types of glaucomatous optic disc abnormality. The correlation of changes of both measurements during a 9-year follow-up period also was statistically significant (r = 0.68, P less than 0.001). CONCLUSION: In clinical routine measurements of the neuroretinal rim area, using both configuration and pallor definition does not seem to add to the information.

Adult↗
PubMed1992

Light scatter in aging and cataractous human lens.

We measured back light scattering of the human lens with the Lens Opacity Meter 701 in order to determine whether it can be used for objective assessment of lens opacities in various types of cataracts. One-hundred and twenty-seven eyes of 127 individuals were examined including 43 healthy volunteers in various age groups and 84 patients with cortical, nuclear, posterior subcapsular or mixed lens opacities. Almost 90% of the total variation in the light scatter values was accounted for by age in non-cataractous eyes. Mean scatter value of every cataract group was statistically significantly higher than that of age matched healthy controls (p less than 0.0001). Highest scatter values were measured in cortical cataracts while the mean values of other types of cataract were not statistically significantly different from each other. The regression between light scatter and visual acuity was statistically significant for each cataract group. However, large variation of visual acuity was found with scatter values below 60. The results indicate that the Interzeag Lens Opacity Meter is able to identify cataractous and non-cataractous eyes and discern at least advanced cortical cataracts from other types of lens opacities.

Adolescent↗
PubMed1992

[How is simplex glaucoma diagnosed?].

Although glaucoma has traditionally been regarded as a disease affecting people over 60 years of age, improved diagnostic methods now enable glaucoma-related changes to be detected already in the 35-40-year-old age group, long before any functional visual changes are present. Since there is no treatment capable of restoring lost visual capacity, the diagnosis should be made and treatment initiated at an early stage before visual deterioration has become manifest. Measurements of intra-ocular pressure and visual acuity provide insufficient guidance, whereas periodic photography of the nerve fibre layer yields early diagnostic information and an indication of the appropriate individual level of intra-ocular pressure to prevent progression of the disease.

Glaucoma, Open-Angle↗
PubMed1991

Initial glaucomatous optic disk and retinal nerve fiber layer abnormalities and their progression.

We attempted to identify the initial glaucomatous changes of the optic disk and retinal nerve fiber layer and to analyze how these changes subsequently progressed. Of 61 eyes of 61 patients with ocular hypertension, 23 (38%) developed glaucoma during ten years of follow-up (range, five to 15 years). The initial sign of glaucomatous damage was diffuse enlargement of the optic disk cup in ten of 23 eyes or generalized thinning of the nerve fiber layer without localized changes in 12 of 23 eyes. We found localized optic disk damage in ten of 23 patients and localized retinal nerve fiber layer damage in 11 of 23 patients alone or in combination with diffuse damage. In 13 of 23 eyes, the cupping ended up in diffuse enlargement with even more profound thinning of the neural rim in the upper and lower temporal disk margins. There seems to be great variability in the appearance and progression of the initial glaucomatous optic disk and nerve fiber layer abnormalities in patients with increased intraocular pressure.

Adult↗
PubMed1991

Lens autofluorescence in healthy individuals.

We measured blue-green autofluorescence (AF, 495 nm/520 nm) of the lens in 43 random eyes of 43 healthy volunteers aged 6-86 years, five in each decade, using an instrument designed by one of us (HN). The instrument generates an autofluorescence profile, which consists of anterior and posterior juxtacortical peaks and a central plateau. The height of the anterior peak was taken as a maximum autofluorescence value and the square root of the ratio between the posterior and the anterior peak was used as a lens transmission index. The coefficient of variation for the measurement technique was 3.9% for maximum autofluorescence and 2.9% for lens transmission index. Both the maximum autofluorescence and the transmission index were highly correlated with age. Statistically over 90% of the variation in maximum autofluorescence values and almost 70% of the variation in transmission could be attributed to age.

Adolescent↗
PubMed1991

Neuroretinal rim area in low tension glaucoma: effect of nifedipine and acetazolamide compared to no treatment.

The purpose of this study was to measure the change of neuroretinal rim area in patients with low tension glaucoma on- and off-treatment. Thirty-two patients were followed up for a mean of 2.6 years. Ten patients received treatment with nifedipine, 11 patients with acetazolamide and 11 patients had no treatment. The total change of rim area and the yearly rate of rim area change did not differ statistically significantly between the three groups. Seven patients in each group suffered from cold hands and feet. The response to cold provocation visual field testing was positive in 25% of patients. Neither the history of cold hands and feet nor the cold provocation test result affected the rate of progression of optic disc abnormalities. Nifedipine and acetazolamide treatment seemed to show no advantage over no-treatment in our patients.

Acetazolamide↗
PubMed1990

The effect of jogging on visual field indices.

The Humphrey 30-2 visual field was examined 9 times before and after an 8-km jog in one subject, whose contrast sensitivity had been found to improve after jogging. The mean deviation improved statistically significantly suggesting better sensitivity of the visual system after jogging. Our results suggest that in some individuals physical exercise influences the factors which lie behind the visual field long-term fluctuation.

Contrast Sensitivity↗