Biomedical subjects

V Malinovsky

Publications and source records attributed to V Malinovsky.

6 recordsLinked to original sources

PubMed1999

Mechanism of exercise-induced ocular hypotension.

PURPOSE: Although acute dynamic exercise reduces intraocular pressure (IOP), the factors that provoke this response remain ill-defined. To determine whether changes in colloid osmotic pressure (COP) cause the IOP changes during exercise, standardized exercise was performed after dehydration and hydration with isosmotic fluid. METHODS: Progressive cycle ergometer exercise to volitional exhaustion was performed after 4 hours' dehydration, and after hydration with 946 ml isosmotic liquid (345 mOsM). In each experiment, venous blood taken before and immediately after exercise was analyzed for hematocrit, plasma protein concentration, total plasma osmolality, and plasma COP. RESULTS: Exercise in both experiments significantly reduced IOP and elevated COP (each P < 0.01). Dehydration, compared with hydration, also significantly reduced IOP and elevated COP, when measured before and after exercise (P < 0.05). The correlation of mean IOP with mean COP, over the entire range created by varying exercise and hydration statuses, was statistically significant (r = -0.99; P < 0.001). In contrast, other indexes of hydration status, including hematocrit, total plasma osmolality, and plasma protein concentration, failed to change as IOP changed and failed to correlate with IOP, on either a group or individual basis, in conditions of varying levels of exercise and hydration. CONCLUSIONS: Acute dynamic exercise and isosmotic fluid ingestion each seem to change IOP through changes in COP.

Blood Proteins↗

PubMed1999

Regulation of intraocular pressure after water drinking.

PURPOSE: Acute oral water loading transiently elevates intraocular pressure (IOP) via mechanisms that remain unexplained. We tested the possibilities that water drinking might elevate IOP by creating a blood-aqueous osmotic gradient, or that it might instead alter active ion pumping and the formation of aqueous humor. METHODS: In the first series, 16 young, healthy individuals were studied during dehydration and for 1 hour after rehydration (14 mL H2O/kg body weight). Hematocrit, total plasma osmolality, and plasma colloid osmotic pressure were determined simultaneously with measurements of IOP. In a second series (N = 16), rehydration occurred after pretreatment with either placebo or a topical carbonic anhydrase inhibitor (1 drop 2% dorzolamide in each eye, 12 and 2 hours before oral water loading). RESULTS: In both series, mean IOP increased significantly 15 minutes after water ingestion and remained elevated above baseline for 45 minutes. In contrast, colloid osmotic pressure and hematocrit were unaltered by water drinking, and neither these variables nor total plasma osmolality correlated with IOP. In the second series, pretreatment with dorzolamide reduced baseline IOP, but failed to alter the magnitude or time course of IOP elevations induced by water drinking. CONCLUSION: Because water drinking failed to create a blood-ocular osmotic pressure gradient, neither vitreous hydration nor increased aqueous ultrafiltration can explain increases in IOP after acute hydration. Because the increase in ocular tension apparently also is independent of active bicarbonate pumping, factors affecting aqueous drainage must explain the water drinking effect.

Aqueous Humor↗

PubMed1995

Clinical implications of intra- and inter-reader agreement in four different automated visual fields.

BACKGROUND: This study was designed and conducted to examine the degree of inter- and intra-reader agreement when four readers evaluate visual fields in patients known to have glaucoma and patients known to not have glaucoma. METHODS: Fifty-three patients known to have glaucoma and 60 patients known not to have glaucoma were selected randomly from a population at the University of Alabama at Birmingham School of Optometry. Four visual fields were performed on each patient, non-dilated, with the proper correction in place. The fields were performed on three different instruments by technicians who were unaware of the diagnostic status of the patient. Four independent (blinded) clinicians read the visual fields and judged them as: "glaucoma field defect," "no glaucoma field defect," and "poor reliability-cannot judge." RESULTS: Statistical analysis revealed that a single reader's interpretation of four different types of visual fields are very different from, are poorer than, and are more consistent than are the four readers' interpretations of a single type of visual field. The analysis also shows that the readers consistently underestimated the number of glaucoma patients with one instrument and overestimated the number with another. CONCLUSIONS: This results suggest that a single visual field will discriminate patients with glaucoma with an accuracy in the 70 to 75 percent range. For one of the instruments, the shorter protocol was almost as effective in discriminating glaucomatous fields as the longer protocol. This study also suggests that repeating the visual fields or analysis of a single field by two readers improves reliability.

Aged↗

PubMed1994

Correlates of acute exercise-induced ocular hypotension.

PURPOSE: To understand those factors that determine the decrease in intraocular pressure (IOP) that occurs during acute dynamic exercise. METHODS: Three aspects of the exercise-IOP relationship were studied. These included graded exercise, with and without CO2 addition for isocapnia; comparison of the IOP response of trained and sedentary subjects to a fixed external work load; and exercise after ocular beta-adrenoceptor blockade. Graded exercise consisted of 7 minutes each at 30 and 90 watts on a cycle ergometer, then progressive work to exhaustion. Trained and sedentary subjects were defined on the basis of the blood lactate response to fixed external work (10 minutes at 90 watts). Selective beta 1-adrenoceptor blockade (betaxolol) and nonselective beta-adrenoceptor blockade (levobunolol) were superimposed on graded exercise. Intraocular pressure was measured using applanation tonometry. RESULTS: Graded exercise: Intraocular pressure decreased in proportion to exercise intensity. Hypocapnia developed in the last minutes of exhausting work, but preventing hypocapnia with CO2 addition failed to lessen the decrease in IOP. Response to fixed external work load: Intraocular pressure decreased significantly more in sedentary than in trained subjects; this decline was correlated with elevations in blood lactate but not with changes in metabolic rate or plasma osmolarity. Selective and nonselective beta-adrenoceptor blockade: Both drugs lowered IOP at baseline and throughout graded exercise; the drugs and exercise had apparently additive ocular hypotensive effects. CONCLUSIONS: Acute dynamic exercise lowers IOP in a graded fashion proportional to relative, not absolute, work load. The IOP decline is correlated with blood lactate but not with PCO2 or plasma osmolarity changes, and exercise potentiates the ocular hypotensive effects of beta-adrenoceptor blockade.

Betaxolol↗

PubMed1993

Diagnosis and management of temporal arteritis: a review and case report.

Temporal arteritis is an insidious disease which, if not recognized and treated with high-dosage oral prednisone or intravenous prednisolone, can result in unilateral or even total blindness due to anterior ischemic optic neuropathy (AION) or closure of the central artery of the retina. Unfortunately, the symptoms and clinical signs of temporal arteritis mimic those of a number of other conditions including angle-closure glaucoma, hypertension, migraine, trigeminal neuralgia, temporomandibular joint syndrome, carotid artery occlusive disease, Foster-Kennedy syndrome, and nonarteritic AION. When a patient complains of a severe pain in the temporal region, along with scalp tenderness and a feeling of malaise or depression--with or without episodes of transient loss of vision--he or she should be referred for a diagnostic work-up which includes an erythrocyte sedimentation rate and a temporal artery biopsy. We present here a review of the recent literature concerning temporal arteritis, followed by a report of an unusual case in which high-dosage prednisone therapy was effective in relieving the patient's symptoms and lowering the sedimentation rate in spite of a negative temporal artery biopsy.

Administration, Oral↗

PubMed1987

Benign essential blepharospasm.

A 57-year-old female had vague visual complaints of pressure behind her right eye during an ocular examination. One month later the patient was visually impaired due to uncontrollable spasms of both eyelids. A diagnosis of benign essential blepharospasm (BEB) was made, and the patient was eventually treated with botulinum toxin to temporarily relieve her symptoms. I have reviewed and summarized the literature relating to the characteristics and management of this often misdiagnosed and misunderstood ocular muscular condition.

Blepharospasm↗