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PubMedDate not supplied

Clinical experience with the Tracey technology wavefront device.

PURPOSE: In refractive surgery, measuring the total ocular profile of refraction gives more vital information than measuring the cornea alone. We report the first clinical experiments with spatially resolved refractometry using ray tracking principles. Tracey technology was developed in Ukraine by the Institute of Biomedical Engineering in cooperation with the Vardinoyannion Eye Institute of Crete. METHODS: The Tracey-1 device was evaluated in comparison with conventional videokeratoscopes. Seven pseudophakic eyes of 7 patients and two phakic eyes were measured thirty (30) consecutive times (consecutively) each to test reproducibility. Measurements were provided in zones 0 to 5 (6) mm. For each zone, parameters of astigmatism were calculated and mean value and standard deviation were derived. RESULTS: Standard deviation on the order of 0.14 D was derived. CONCLUSION: The Tracey Technology wavefront device provides information on the refraction distribution at the first principal plane of the ocular optical system. For the instrument to provide measurements that are directly applicable to clinical practice, the data should be transposed to the corneal plane. The Tracey device can be utilized for the measurement of accommodative amplitude and range. Further development of the instrument is requred to increase its accuracy.

Accommodation, Ocular↗
PubMedDate not supplied

Objective measurement of wavefront aberrations with and without accommodation.

PURPOSE: The measurement of the refractive error profile is more useful than corneal topography in understanding the complexities of refractive surgery. We report on experimental studies of the spatially resolved refractometer Tracey-1, developed in Ukraine by IBME in medical cooperation with VEIC, Greece. METHODS: Ten eyes were subjected to dynamic measurement of accommodation, in order to test the effectiveness of Tracey refractometry. Measurements were performed in zones 0 to 6 mm. The refractive aberrations were calculated and accommodation was evaluated. RESULTS: Evaluation of data shows that the instrument can effectively follow the dynamic change of refractive aberrations through the accommodation process. CONCLUSION: Clinical tests of Tracey technology demonstrated the ability to investigate accommodation using this instrument.

Accommodation, Ocular↗
PubMed1982

Colostrum deficiency in mule deer fawns: identification, treatment and influence on neonatal mortality.

Glutaraldehyde coagulation test, zinc sulfate turbidity test, and total protein refractometry were adapted for use in detecting failure of passive transfer of colostral immunoglobulins to mule deer fawns (Odocoileus hemionus). The results of all three tests were similar. Serum total protein concentration was directly correlated to gamma globulin concentration and gave the best indication of morbidity and mortality. Thirteen of 13 fawns with serum total protein concentrations of 5 g/dl or less at 1 to 7 days of age developed diarrhea and died before 17 days of age. Only 1 of 14 fawns having a serum protein concentration above this level became sick and died. Seven of 13 fawns that had serum total protein concentrations of 5 g/dl or less, and that had already developed diarrhea, were given 20 ml of plasma per kg body weight. Although this increased their serum gamma globulin concentrations 0.3 g/dl, none survived. Administration of bovine colostrum to one fawn increased its serum gamma globulin concentration suggesting that mule deer fawns are able to absorb gamma globulins from bovine colostrum.

Animals↗
PubMed1999

Latrunculin-A causes mydriasis and cycloplegia in the cynomolgus monkey.

PURPOSE: To determine the effect of latrunculin (LAT)-A, which binds to G-actin and disassembles actin filaments, on the pupil, accommodation, and isolated ciliary muscle (CM) contraction in monkeys. METHODS: Pupil diameter (vernier calipers) and refraction (coincidence refractometry) were measured every 15 minutes from 0.75 to 3.5 hours after topical LAT-A 42 microg (approximately 10 microM in the anterior chamber [AC]). Refraction was measured every 5 minutes from 0.5 to 1.5 hours after intracameral injection of 10 microl of 50 microM LAT-A (approximately 5 microM in AC), with intramuscular infusion of 1.5 mg/kg pilocarpine HCl (PILO) during the first 15 minutes of measurements. Pupil diameter was measured at 1 and 2 hours, and refraction was measured every 5 minutes from 1 to 2 hours, after intravitreal injection of 20 microl of 1.25 mM LAT-A (approximately 10 microM in vitreous), with intramuscular infusion of 1.5 mg/kg PILO during the first 15 minutes of measurements (all after topical 2.5% phenylephrine), and contractile response of isolated CM strips, obtained <1 hour postmortem and mounted in a perfusion apparatus, to 10 microM PILO +/- LAT-A was measured at various concentrations. RESULTS: Topical LAT-A of 42 microg dilated the pupil without affecting refraction. Intracameral LAT-A of 5 microM inhibited miotic and accommodative responses to intramuscular PILO. Intravitreal LAT-A of 10 microM had no effect on accommodative or miotic responses to intramuscular PILO. LAT-A dose-dependently relaxed the PILO-contracted CM by up to 50% at 3 microM in both the longitudinal and circular vectors. CONCLUSIONS: In monkeys, LAT-A causes mydriasis and cycloplegia, perhaps related to its known ability to disrupt the actin microfilament network and consequently to affect cell contractility and adhesion. Effects of LAT-A on the iris and CM may have significant physiological and clinical implications.

Accommodation, Ocular↗
PubMed1999

Refinement of a rodent model of peripheral lymphedema.

A reliable, inexpensive experimental counterpart of peripheral lymphedema has been notoriously difficult to reproduce thereby stifling basic and clinical research into this frustrating clinical condition. Accordingly, in 45 adult Wistar-Fuzzy rats, we attempted to produce sustained hindlimb lymphedema by either groin nodal/lymphatic microsurgical ablation (S) (guided by visual blue dye lymphography) or limited field-groin irradiation (R) alone (4500 rads) or combined S followed by R or R followed by S with an additional non-manipulated group serving as controls. Observations were made for 30-100 days thereafter. Hindlimb volumes were determined serially using the truncated cone formula based on multiple circumferential measurements at standardized intervals along the affected hindlimb and the findings compared with similar measurements in the contralateral non-manipulated hindlimb. In randomly selected rats from each group, lymphatic drainage was assessed by lymphangioscintigraphy (LAS), soft tissue swelling by magnetic resonance imaging (MRI), and edema fluid total protein content by refractometry. Whereas S or R alone produced only transient or mild hindlimb edema without associated morbidity or mortality, S-R or R-S induced moderate to severe sustained protein-rich hindlimb lymphedema associated with 9-13% early mortality and notable late local limb morbidity. Lymphatic obstruction was documented by sustained maintenance of increased hindlimb volume, subcutaneous fluid accumulation (MRI), and impaired lymphatic drainage (LAS). This reproducible rodent model of secondary lymphedema reliably simulates a stable clinical condition for a window of up to 100 days and should thereby facilitate standardized testing of therapeutic/preventive protocols and basic research into lymphatic dynamics in secondary lymphedema.

Animals↗
PubMed2000

Choroidal thickness changes during altered eye growth and refractive state in a primate.

PURPOSE: In the chick, compensation for experimentally induced defocus involves changes in the thickness of the choroid. The choroid thickens in response to imposed myopic defocus and thins in response to imposed hyperopic defocus. This study was undertaken to determine whether similar choroidal changes occur in the primate eye with induced refractive errors. METHODS: Thirty-three common marmosets were used. Eyes in 26 monkeys served as untreated control eyes, and eyes in 7 received 3 weeks of monocular lid suture to induce changes in eye growth and refractive state. Refractive errors were measured using refractometry and retinoscopy, and axial ocular dimensions, including choroidal thickness, were measured using high-frequency A-scan ultrasonography. Eyes were measured before the lids were sutured and at frequent intervals after lid opening. RESULTS: In the marmoset, choroidal thickness ranges from 88 to 150 microm and increases significantly during the first year of life. Monocular lid suture initially results in short, hyperopic eyes that then become elongated and myopic. In these animals the choroids of both the experimental and the fellow control eyes also increase in thickness with age but additionally show interocular differences that vary significantly with the relative changes in vitreous chamber depth and refraction. In eyes that are shorter and more hyperopic than control eyes the choroids are thicker, and in eyes that are longer and more myopic than control eyes the choroids are thinner. CONCLUSIONS: In marmosets, the thickness of the choroid increases during postnatal eye growth. Superimposed on this developmental increase in choroidal thickness there are changes in thickness that are correlated with the induced changes in eye size. These changes are small (<50 microm) in comparison with those observed in the chick, contributing to less than a diopter change in refractive error.

Aging↗
PubMedDate not supplied

Changes in the lymphocyte cytoplasmic refractive index following typhoid vaccination.

The refractive index of the circulating blood lymphocytes (LCRI) of healthy young adults vaccinated with typhoid vaccine has been measured by immersion refractometry and phase contrast microscopy. A rise in the LCRI preceeds the rise in the antibody titre by two to three days. A more pronounced rise also occurred in one patient prior to a rejection crises following a kidney transplant.

Adolescent↗
PubMed2000

[A myopia study of glaucoma patients following pilocarpine instillation].

AIM: Our research studies transitory myopia induced by Pilocarpine treatment in glaucoma patients. MATERIAL AND METHODS: 48 patients with open angle glaucoma were selected, visual acuity and refraction were measured before and after the instillation of Pilocarpine 2%, for two hours. Induced myopia was compared for different ages and it was established the influence of Timolol and Acetazolamide administered in the same time. RESULTS: Transitory myopia is important in young patients, reduced after 50 years and absent after 70 years. Acetazolamide increases myopia, Timolol has no effect on refraction. CONCLUSIONS: The study confirms the unpleasant effect of Pilocarpine and suggests not performing refractometry in the first two hours after the instillation of the drug.

Adult↗
PubMed2000

Preliminary report: examination of young children with Lea symbols.

BACKGROUND: Lea symbols are highly sensitive for detection of amblyopia in cooperative patients. They are favorable for visual acuity assessment in childhood. Therefore, we assessed age-related normal values and interocular differences of Lea symbol visual acuity. METHODS/PATIENTS: We reexamined 50 out of 193 children aged 21 months to 7 years who came for a routine pediatric examination between January and November 1999. Lea symbol acuity (Lea Symbols Single Symbol Book (LS) and Lea 15-Line Folding Distance Chart (CLS)) and Landolt-C acuity (single (LC) and crowded with 2.6' inter-optotype distance (LC(2.6))) were measured. A three out of four criterion was used. Strabismus and any organic eye disease were excluded by orthoptic and ophthalmologic examination, consisting of biomicroscopy, ophthalmoscopy, retinoscopy or refractometry, cover test or Hirschberg test and Lang Stereotest. RESULTS: Only 26% of the parents (50 out of 193) accepted an examination in our hospital. In 35 (32) of the 50 children, visual acuity could be measured in both eyes separately with single (crowded) Lea symbols, while 26 (25) children could be examined in both eyes monocularly with the Landolt-C with single (crowded) optotypes. Except for one 3-year-old boy, all of the children older than 30 months could be tested with single Lea symbols. Lea acuity surpassed Landolt acuity. The difference was about 1.5 lines (1.5 dB) for both the single and the crowded optotypes. In 63% (69%) of the children who could be tested monocularly, LS acuity (CLS acuity) was higher than 0.8 (0.63). 89% (83%) of the children had an interocular difference of maximum 1 line for single (crowded) Lea symbols. CONCLUSIONS: The youngest child whose visual acuity could be assessed with Lea symbols was 23 months old. Almost every child older than 30 months could be tested with Lea symbols. Lea acuity higher than 1 and an interocular difference less than 2 lines is not suspect for amblyopia. Children with a difference of more than one line should be reexamined.

Amblyopia↗
PubMed2001

Effects of nicotinic antagonists on ocular growth and experimental myopia.

PURPOSE: To learn whether nicotinic cholinergic receptors modulate postnatal eye growth and influence the course of form-deprivation myopia. METHODS: One-week-old White Leghorn chicks wore a unilateral goggle to induce form-deprivation myopia. Other chicks were never goggled. Nicotinic antagonist drugs were administered by intravitreal injection, usually daily or every other day to the goggled eye or to one eye of never-goggled chicks. After 1 week, the eyes were studied by refractometry, A-scan ultrasonography, and caliper measurements. RESULTS: The relatively non-subtype-specific channel-blocking nicotinic antagonists chlorisondamine and mecamylamine each inhibited the development of form-deprivation myopia but with complex multiphasic dose responses. Chlorisondamine was the most effective. Mecamylamine, at the lowest tested doses, tended to stimulate the growth response and myopic refractive shift of goggle wearing. Methyllycaconitine competitively inhibits nicotinic receptors containing the alpha7 and alpha8 subunits, which are highly expressed in chick retina. It showed a less dramatic but still significant inhibitory effect on myopia. The effects of dihydro-beta-erythroidine, a competitive antagonist relatively selective for nicotinic receptors with alpha3 or alpha4 subunits and particularly for alpha3beta2-containing receptors, were the weakest and inhibited primarily axial elongation. Chlorisondamine but not mecamylamine also affected nongoggled eyes, inhibiting growth and shifting refraction toward hyperopia, but chlorisondamine also induced degenerative changes to the retinal pigment epithelium (RPE). CONCLUSIONS: Nicotinic receptors are involved in eye growth control. Nicotinic antagonists affect the development of form-deprivation myopia and perhaps the growth of nongoggled eyes. The differences in drug activity and multiphasic dose-response curves may reflect the complexity of nicotinic receptor subtypes associated with the eye and/or pharmacokinetic differences between the individual drugs. Although another tissue(s) cannot be completely excluded by these data, the site of action of these agents may be neural retina or RPE.

Animals↗
PubMed1975

[Some quantitative characteristics of the frog retinal rod outer segments].

Retinal rod outer segments in frogs were studied by means of light microscopy, refractometry, microspectrophotometry, and electron microscopy. Analysis of the data obtained shows that an unidentified substance, which makes up about 50% of outer segment dry weight, is lost during routine biochemical investigations. The protein parts of the rhodopsin molecules make up 85% of the outer segments proteins and 25% of outer segment dry weight. Rhodopsin molecules can be arranged in a square array with a unit cell side of about 7 nm on one side of each disk membrane. Lipids in a single membrane occupy only 2 nm, and disk membranes are strongly hydrated.

Animals↗
PubMed2001

[Biometric variation of the ocular globe in myopia].

GOAL: The study of correlation between myopia's pathogen and the biometrics variations of the different eye ball segments. MATERIAL AND METHOD: 64 patients were included in this study: 54 patients with myopia higher than--5 diopter and 10 patients with cataracta. All patients underwent a complete ocular examination including: visual acuity determination, ocular fundus examination, automatic refractometry, keratometry. Biometry was performed with an ultra-scan system. RESULTS: From 64 patients, 53 were with axial myopia, 1 with myopia induced by low corneal curvature radius and 10 patients with myopia induced by a high refractive index of the lens caused by cataract. In cases with axial myopia the axial length was high (26.1 mm) with a high vitreous length (20.78 mm). In cases with index myopia, only the lens thickness and the anterior chamber depth undergo biometrics variations. Curvature myopia is the result of the decrease of the corneal curvature radius. CONCLUSIONS: Axial myopia is that by far the most frequently form of myopia. In this case the increases in axial length is proportionally with the degree of myopia. Index myopia is produced by the increase of the refractive index of the lens in cataract. A low corneal curvature radius less frequently than the others produces curvature myopia.

Adolescent↗
PubMed1976

Objective evaluation of experimental ocular irritation.

After topically administered nitrogen mustard the irritative effect on the pupil, intraocular pressure, protein concentration of the aqueous humor and on the vessels of the iris and conjunctiva was quantified. The protein level in aqueous was determined by refractometry. The degree of hyperemia of conjunctiva and iris was determined by measuring the amount of Evans blue dye present in the tissue minutes after intravenous administration. A reproducible relationship was obtained using these methods to evaluate the degree of irritation produced by nitrogen mustard.

Animals↗
PubMed1990

[Aberrometry in the diagnosis of eye diseases].

Four methods (by means of Smirnova-Korniushina's aberrometer; with the help of aberroscope--Cherning's lattice; by presenting a figure of a cross; and by automatic refractometry through different portions of the pupil) were used for studying aberration of the optic system of the eye in 490 persons. Among them, 37 were healthy persons, 27--patients with ametropia of moderate degree, 24--with high myopia, 9--with astigmatism above 3.0 D, 16--with monocular diplopia, 327--with keratoconus, 7--with scars of the cornea, 21--with initial cataract, 47--after keratotomy. In norm and in ametropia to 6.0 D, a histogram of refraction distribution by the pupil has a small disperse and a pronounced peak, the Cherning's lattice is straight. In high myopia, the disperse of refraction increases, the peak is slightly pronounced, the lattice is curved along the margins. In astigmatism, the disperse of refraction is great, but there can be peaks. The whole lattice is curved. In monocular diplopia, two more peaks can be seen on the histogram. The lattice is greatly curved. In keratoconus, aberrometry without correction is possible only at the initial stage and shows a rather mixed picture. The histogram of refraction represents a low irregular row. In aberroscopy, the bands are greatly curved, frequently overstep the bounds of the frame that itself looses a form of a circle, becomes oval or polygonal. Contact correction improves the aberration picture considerably. In scars of the cornea, the lattice is distorted and infrequently repeats their forms. In initial cataract, the course of the bands becomes interrupted and rounded spots appear between them.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Effect of interleukin-2 on microvascular liquid and protein transport in the rat small intestine.

Interleukin-2 (IL-2), a glycoprotein lymphokine derived from activated T-lymphocytes displays potent anti-cancer properties but its therapeutic use has been limited by generalized tissue swelling. To shed light on the mechanism underlying this potentially life-threatening edematogenic syndrome, recombinant IL-2 or an equal volume of control solution (excipient or 5% dextrose) was administered to 88 adult, male Sprague-Dawley rats. Initially, rats were injected with 50,000 Cetus units (equal to 300,000 I.U.) of IL-2 intraperitoneally, either one-time ("acute" rats) or every eight hours for two or seven days ("chronic" rats). Thereafter, under pentobarbital anesthesia, the main mesenteric lymph duct was isolated, incised, and measurements made of intestinal lymph flow (JV) and the total protein content and protein fractions in lymph (L) and plasma (P) (refractometry and agarose gel electrophoresis, respectively). Final measurements were also carried out after superior mesenteric vein constriction to assess filtration-independent L/P total protein "washdown." After IL-2, JV and protein clearance (JV x L/P) were increased (p less than 0.001) while lymph and plasma total protein content and protein fractionation were unchanged. Protein washdown was also maintained. These data are not only inconsistent with bulk "plasma leak" from damaged capillaries, but in conjunction with previously demonstrated increased cardiac output and reduced systemic vascular resistance after IL-2 administration, the findings favor augmented microvascular surface exchange area from increased capillary perfusion as the primary mechanism underlying increased transcapillary liquid and protein flux. This conclusion conforms to the rapid reversal of edema in patients after cessation of IL-2 therapy.

Animals↗
PubMed1987

Clinical pathologic alterations in horses during a water deprivation test.

A 72-hour water deprivation test was performed in 12 horses to determine clinical pathologic changes. Reference values for electrolyte (X) clearance, expressed as a percentage of creatinine clearance (CLCR; %CLCRX), were also determined. A comparison was made between urine concentration measurement techniques. Results of %CLCRX determination in 12 horses before water deprivation were 0.034 +/- 0.095 %CLCRNa, 42.4 +/- 9.8 %CLCRK, 0.352 +/- 0.190 %CLCRCl, and 0.710 +/- 0.250 %CLCRP. During water deprivation, there was individual variation for electrolyte clearances, but Na excretion increased significantly (P less than 0.01) at 24 and 48 hours. After 48 hours' water deprivation, %CLCRNa decreased significantly, but was still greater than the initial clearance. Plasma protein was a better indicator of water deprivation (dehydration) in the horse than was PCV. Electrolyte concentrations in serum and urine were determined. Little significant (P less than 0.01) change in acid-base values was noticed after 72 hours' water deprivation. Urine osmolality (as determined by osmometry) was compared with sp gr (determined by refractometry) in determining urine concentration. Initially, sp gr correlated well with urine osmolality determinations, but this correlation decreased after 48 hours.

Animals↗
PubMed1985

Immunoglobulin transfer and weight gains in suckled beef calves force-fed stored colostrum.

Concentrations of immunoglobulins and total proteins in second-day post-partum serum samples of 62 beef calves from multiparous dams were measured by zinc sulphate turbidity, electrophoresis, radial immunodiffusion and refractometry. These results, together with health records and weight gains, were used to evaluate the practice of routinely force-feeding 1 L of stored colostrum to suckled beef calves immediately after birth. There was no apparent benefit from such force-feeding. It did not result in greater 48-hour serum immunoglobulin levels, nor did it improve weight gains at 42 days. None of the calves required treatment for neonatal disease, but one force-fed calf died from inhalation of regurgitated colostrum.

Animals↗
PubMed1971

Quantitation of serum lipoproteins by electrophoresis on agarose gel: standardization in lipoprotein concentration units (mg-100 ml) by comparison with analytical ultracentrifugation.

Lipoprotein electrophoresis on agarose gel has been modified to allow estimation of the absolute quantity of each fraction. The reproducibility of the method is illustrated by 12 determinations in a single day on serum from one normal subject: mean total dye uptake was 302 +/- 9 (sd "corrected dye units," and the percentages of beta-, pre-beta, and alpha-lipoprotein were 56.1 +/- 0.9, 29.1 +/- 0.4, and 14.8 +/- 0.7, respectively. Reproducibility over a period of 8 months was also demonstrated. Serum lipoproteins of five normal and 15 hyperlipidemic individuals determined by this technique were compared with values obtained by analytical ultracentrifugation. The correlation coefficients were: 0.993 for pre-beta-LP vs. VLDL, 0.978 for beta-LP vs. LDL, and 0.867 for alpha-LP vs. HDL. Lipoprotein values obtained by paper electrophoresis were also correlated with those of the analytical ultracentrifuge, but to a lesser degree (r = 0.956, 0.691, and 0.786, respectively). Values for LDL and VLDL which were measured by refractometry after preparative ultracentrifugation were very similar to those obtained from the analytical ultracentrifuge. Serum triglyceride concentration was highly correlated (r = 0.972) with the agarose values for pre-beta-LP; serum cholesterol concentration was correlated (r = 0.673) with beta-LP. It is proposed that the standard curves of the comparisons with the analytical ultracentrifugal values be used to convert the corrected dye units of electrophoresis on agarose gel to mg/100 ml of specific lipoprotein.

Adult↗