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PubMed1984

Vitreous fluorophotometry in patients with cone-rod dystrophy.

Eight patients with cone-rod dystrophy were examined by means of vitreous fluorophotometry. The data in three patients with an early stage of retinitis pigmentosa (rod-cone dystrophy) served for comparison. In contrast with the abnormal findings on vitreous fluorophotometry in patients with an early stage of retinitis pigmentosa the value of vitreous fluorophotometry in cone-rod dystrophy was within the normal range in all patients except the two with advanced stages of this disease. Our results suggest that, although both diseases are based on diffuse dystrophy of photoreceptors, and the final stages of the two diseases may show several similar features, the process of breakdown of the blood retinal barrier differs greatly in the two diseases.

Adolescent↗
PubMed1987

Vitreous fluorophotometry in patients with senile macular degeneration.

Twenty-two phakic eyes of 16 patients with varying stages of senile macular degeneration (SMD) underwent vitreous fluorophotometry. The upper tolerance limit of the penetration ratio in 17 eyes of 17 age-matched controls was 6.33 X 10(-6) min-1. Ten of the 22 eyes with SMD had values exceeding this, indicating abnormal blood-retinal barrier function. When the fluorescence recorded in the vitreous but not related to the local intravitreal dye was evaluated, it was greater in those eyes with more severe forms of the disease. All ten eyes with drusen alone and no SMD had normal fluorophotometry values. Vitreous fluorophotometry may be helpful in the diagnosis and classification of SMD.

Aged↗
PubMed1996

Comparative study of three methods of evaluation of the corneal endothelium in pseudophakic patients: fluorophotometry, specular microscopy and pachymetry.

BACKGROUND: At present, three techniques, based on different methodological suppositions, are used indiscriminately for the study of the corneal endothelium. These are pachymetry, specular microscopy and fluorophotometry. The purpose of this work was to study the corneal endothelium of pseudophakic patients with the three techniques mentioned. On the basis of the results obtained, we discuss the relations between them and their practical clinical utility. METHODS: One hundred and fourteen eyes of pseudophakic patients were studied using the three corneal endothelial evaluation techniques, both in the immediate pre-operative period and 1 year after surgery. RESULTS: Statistically significant relations exist between the number of endothelial cells and the fluorophotometric endothelial permeability coefficient (Kc.ca) 12 months after surgery, between the increase in corneal thickness in the first week after the operation and the Kc.ca 12 months after surgery, and between fluctuations of the corneal thickness greater than 30 microns and both the endothelial cell count and the Kc.ca 12 months after surgery. There are no significant relationships among the pre-operative values obtained with the three methods. CONCLUSION: The results show how the parameters measured with the functional techniques (fluorophotometry, pachymetry) generally become normal after the surgical trauma, while the endothelial cell count remains irreversibly altered. The results obtained with different techniques are more closely related in more pathological endothelia, while no relation among them are shown in the study of normal endothelia. It is also shown how pachymetry is a good clinical predictor, in the immediate post-operative period, of the long-term status of the corneal endothelium.

Cataract↗
PubMed1994

Fluorophotometry in myopic phakic eyes with anterior chamber intraocular lenses to correct severe myopia.

Implanting an anterior chamber intraocular lens in a phakic eye is an effective surgical procedure for the correction of severe myopia. However, the potential risks on the anterior segment structures are scarcely known. We conducted a prospective study to evaluate the permeability of the blood-aqueous barrier and the lens transmittance changes after Worst-Fechner lenses were implanted to correct myopia. Preoperative and serial postoperative fluorophotometry was done in 15 eyes that had a Worst-Fechner lens implanted to correct myopia. Lens transmittance was evaluated by lens autofluorescence, and permeability of the blood-aqueous barrier was estimated by anterior vitreous fluorophotometry, which was carried out before and after intravenous injection of fluorescein. Preoperative lens transmittance was 0.971 +/- 0.002 (mean +/- standard error), and, after the operation, lens transmittance decreased to 0.970 +/- 0.002 at one month, 0.966 +/- 0.001 at three months, 0.964 +/- 0.002 at six months, and 0.962 +/- 0.003 at 14 months. At three, six, and 14 months after the operation, lens transmittance values were significantly lower than preoperative values (P = .038 at three months, P < .001 at six months, and P = .005 at 14 months). Fluorescein concentration in the anterior vitreous was 18.522 +/- 1.797 ng/ml (mean +/- standard error) preoperatively and was 21.328 +/- 1.667 ng/ml at one month, 27.518 +/- 1.412 ng/ml at three months, 27.150 +/- 1.474 ng/ml at six months, and 27.012 +/- 1.980 ng/ml at 14 months postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

Fluorophotometry in patients with human immunodeficiency virus with and without cytomegalovirus retinitis.

OBJECTIVE: To study the aqueous humor dynamics in subjects with human immunodeficiency virus (HIV) with and without cytomegalovirus (CMV) retinitis. DESIGN: Prospective cross-sectional study. PARTICIPANTS: Fourteen HIV-positive subjects (27 eyes, 19 with CMV retinitis and 8 without CMV retinitis), and a control group of 9 HIV-negative subjects (17 eyes). TESTING: Fluorophotometry. MAIN OUTCOME MEASURES: Aqueous flow rates as measured by fluorophotometry and intraocular pressure (IOP). RESULTS: Analysis of variance of the mean corrected aqueous flow rate revealed that both HIV-positive groups had significantly lower aqueous flow rates than did the control group (P < 0.03). No difference in mean aqueous flow rates was found between the HIV-positive eyes with or without CMV retinitis. Comparison of mean IOP revealed that HIV-positive eyes with CMV retinitis had significantly lower IOP than did the HIV-positive eyes without CMV retinitis (P = 0.03) and HIV-negative subjects (P = 0.002). There was no correlation between aqueous flow rate and IOP in HIV-positive subjects (P > 0.5). CONCLUSION: The lack of correlation between the aqueous flow rate and IOP suggests that there may be some disassociation between these parameters in HIV-positive patients. Further studies are needed to better understand the mechanism of aqueous formation and in the management of disorders affecting IOP in this population.

AIDS-Related Opportunistic Infections↗
PubMed2000

Can vitreous fluorophotometry predict the necessity for photocoagulation? A 5-year follow-up study.

PURPOSE: To examine the long-term outcome of vitreous fluorophotometry including the predictability of retinopathic proliferative development in diabetic subjects. METHODS: 21 diabetic subjects were examined by long-term kinetic vitreous fluorophotometry and their barrier properties, as revealed by a permeability-index, were compared to a group of normal subjects. 13 diabetics were classified as having a high permeability-index, while 8 diabetics were classified as having a low permeability-index. The two groups were followed for 5 years with regard to development of proliferative retinopathy. RESULTS: 6 of 13 diabetics with a high permeability-index developed proliferative retinopathy within the 5-year follow-up period. This was in contrast to the low permeability-index group where none of 8 diabetics developed proliferative retinopathy. CONCLUSION: An increased permeability-index points towards an increased risk of development of proliferative retinopathy.

Adult↗
PubMed1993

[The blood-retina barrier and blood-aqueous humor barrier in type I diabetic patients without retinopathy. Determination of permeability using fluorophotometry and laser flare measurements].

BACKGROUND: Possibly early functional disruption of the blood-ocular barrier in eyes of insulin dependent type I diabetics without manifestation of retinopathy can be detected using fluorophotometry and laser flare measurement. MATERIAL AND METHODS: In order to evaluate blood-retinal (BRB) and blood-aqueous-barrier (BAB) permeability fluorophotometry was performed in 34 eyes of 34 insulin-dependent type-I diabetics without retinopathy, additionally the aqueous laser flare was measured. 34 normal eyes of 34 age-matched subjects served as controls. RESULTS: BRB permeability (3.2 +/- 1.3 x 10(-7) cm/s) was increased with low significance (p = 0.019) in diabetic eyes (controls: 2.6 +/- 0.7). The permeability coefficient of BAB was found to be increased in diabetics (5.3 +/- 1.8 x 10(-4)/cm) with higher significance (controls: 3.7 +/- 0.7; p = 0.00003); laser flare values in diabetic eyes (5.0 +/- 1.2 photon counts/ms) were significantly higher than in controls (4.1 +/- 1.0; p = 0.003). In diabetics there was a significant correlation (r = 0.3; p = 0.014) between the laser flare values and the permeability coefficient of BAB. CONCLUSIONS: In type-I diabetics without retinopathy BRB permeability seems to be increased slightly as well as laser flare in the aqueous; the BAB permeability coefficient seems to be the most sensitive parameter in a beginning affection of the blood-ocular barrier.

Adult↗
PubMed1998

Fluorophotometry in contact lens research: the next step.

BACKGROUND: Fluorophotometry can be used to quantify changes in epithelial permeability (Pdc), corneal pH, and tear exchange (T95; time to deplete 95% of a fluorescent dye from beneath a contact lens) associated with contact lens wear. Using fluorometric procedures, we present previously reported data in order to review the effects of contact lens wear on Pdc and pH. We also introduce a new method for measuring tear exchange beneath a soft contact lens and present preliminary data. METHODS: Pdc was assessed on 32 subjects after 1 h of closed-eye soft contact lens wear. Stromal pH was assessed on 21 subjects wearing lenses with a range of different oxygen transmissibilities (Dk/L). T95 was assessed on 7 subjects who wore disposable lenses. Pdc estimates were derived by measuring the rate at which topically applied fluorescein crossed the epithelial barrier from the tears; corneal pH was quantified by alternately exciting a fluorescein-loaded cornea with two wavelengths of blue light and calculating the fluorescence intensity ratio (490/450 nm), which is pH-sensitive; and the T95 was estimated by applying 2 microliters of FITC-Dextran to the posterior surface of a soft contact lens and the monitoring the exponential decay of dye under the lens. RESULTS: On average, 1 h of closed-eye contact lens wear caused a 41% increase in Pdc compared to the control eye. Corneal pH varied directly with a decrease in Dk/L. On average the T95 under contact lenses (mean = 29 min) was slow compared to normal rates with no lens (approximately 5 min). CONCLUSIONS: Fluorophotometry can be used to quantify some interesting effects associated with contact lens wear, and the use of these techniques may provide new information about the impact of contact lens wear on corneal structure and function.

Cell Membrane Permeability↗
PubMed1990

Vitreous fluorophotometry in patients with Best's macular dystrophy.

Ten patients with Best's macular dystrophy were examined with vitreous fluorophotometry and results were compared with a normal population. Seventeen of the 20 affected eyes demonstrated an intact blood-retinal barrier with normal inward permeability of fluorescein dye. Despite diffuse functional impairment of the retinal pigment epithelium (RPE), determined by electro-oculography, as well as accumulation of a lipofuscin or lipofuscin-like substance within virtually all RPE cells, the blood-retinal barrier function of these cells remained intact as determined by clinical fluorophotometry. Similar findings have previously been noted in another hereditary retinal disorder (fundus flavimaculatus) in which a lipofuscin-like substance also accumulates diffusely within RPE cells.

Adolescent↗
PubMed1997

Reproducibility of vitreous fluorophotometry in patients with type 1 diabetes mellitus.

We assessed the day-to-day reproducible of vitreous fluorophotometry in 7 type 1 diabetic patients and in 1 healthy control subject. The coefficient of variation for duplicate measurements was 33.7, 40.3 and 23.6%, for the right eyes, the left eyes and mean values of both eyes, respectively. Assessment of reproducibility in 1 healthy subject, measured 4 times, resulted in coefficients of variation of about 60%. These values are somewhat worse than those obtained by others in healthy subjects. Since technical problems do not seem to play a significant role in this regard, our reproducibility results reflect the true biological variability of the permeability of the blood-retina barrier assessed by vitreous fluorophotometry in diabetic patients. This variability is substantial. Therefore, we conclude that this method is not precise enough to be used in intervention studies with a limited number of subjects.

Adult↗
PubMed1993

A comparison of two methods of measuring aqueous flow in humans: fluorophotometry and flare measurement.

The technique of Anjou and Krakau for measuring flare and Krakau's method for estimating aqueous humor flow in humans was compared to the fluorophotometric procedure of Jones and Maurice. The precision of flare was measured in 20 normal human volunteers, and the precision of flow was measured with fluorophotometry in 24 volunteers. In addition, the circadian rhythms of both flow and flare were measured simultaneously in a separate group of 20 subjects. This simultaneous measurement allowed us to calculate the entry rate of scattering substances into the aqueous humor as a function of time of day. This entry rate is critical for measuring flow by the method of Krakau. The mean coefficient of variation (+/- SD) of repeated measurements of flare at the same time of day was 23.2% +/- 10.3%. The mean coefficient of variation of the measurement of aqueous flow by fluorophotometry was 15.9% +/- 8.2%, significantly better than the measurement of flare (p = 0.01). The daytime entry rate of scattering substances into the aqueous humor varied from 1.39 +/- 0.86 microgram/min (calculated as albumin) to 1.05 +/- 0.58 microgram/min. The rates in daytime hours were not significantly different from each other. At night during sleep, the entry rate was 0.67 +/- 0.48 microgram/min, significantly slower (p between 0.002 and < 0.001). These data indicate that the flare technique cannot be used alone to calculate the circadian rhythm of flow and that direct measurement of flow by fluorescein clearance is likely to be the most repeatable and accurate of the two.

Aqueous Humor↗
PubMed2002

Derivation of lenticular transmittance from fluorophotometry.

PURPOSE: To derive transmittance spectra for the human lens using the ratio between posterior and anterior autofluorescence of the lens as measured by fluorophotometry. METHODS: Transmittance spectra of the lens can be described with a one-parameter model to a high degree of accuracy. The parameter m of this model defines the differences between lens transmittance spectra of individuals. In fluorophotometry literature another parameter related to lens transmittance, T, has been defined as the square root of the ratio between posterior and anterior lenticular autofluorescence. T can be predicted from parameter m, given the spectra of the excitation light, of the fluorescence emitted by the lens and of the detecting device are known, and assuming that the anterior and posterior fluorescence efficiencies of the lens are equal. When this relation is inverted, parameter m can be derived from T, giving the complete transmittance spectrum on the basis of T. RESULTS: A transformation curve was calculated to determine T from m and vice versa. The light transmittance spectrum of the lens was calculated as a function of T. The validity of this approach was evaluated using an independent method for assessment of lenticular transmittance. This method consisted of making color slitlamp slides, grading the observed color of these slides with the LOCS III NC grading system, and transforming these grades into the model parameter m using published transformation curves. CONCLUSIONS: The total transmittance spectrum can be calculated reliably from a fluorophotometric scan of the human lens.

Aged↗
PubMed1991

[Fluorophotometry and corneal endothelium].

The corneal endothelium plays a major part in corneal deturgence and hydratation by functioning as a barrier and a pump. Fluorophotometry enables assessment of this barrier function because of endothelial permeability to fluorescein. After a description of the technique of fluorophotometry, the authors show its interest in the understanding of endothelial physiopathology: during aging, in compensated or decompensated endothelial dystrophy, during lens and corneal surgery, in irido-corneal endothelial syndrome and in pharmacology.

Biological Transport↗
PubMed1990

Fluid movement across the blood-retinal barrier: a review of studies by vitreous fluorophotometry.

Vitreous fluorophotometry was used to study the fluid movement across the blood-retinal barrier. The effect of plasma osmolality and intraocular pressure on the movement of the fluorescent tracer confirmed the interaction between the tracers and the fluid flow across the blood-retinal barrier. The measurement of outward and inward permeabilities to carboxyfluorescein revealed the existence of a posteriorly directed fluid flow in the vitreous cavity of cynomolgus monkey eyes with retinal detachment. Fluid movement across the blood-retinal barrier was shown to be inhibited by furosemide and enhanced by acetazolamide. Furthermore, vitreous fluorophotometry proved to be useful in estimating the in vivo fluid dynamics in the vitreous and across the human retina.

Animals↗
PubMedDate not supplied

[Functional evaluation of the corneal endothelium using anterior segment fluorophotometry].

The AA have studied the permeability of the corneal endothelium by anterior segment fluorophotometry using instillation of fluorescein. The Fluorotron Master TM has been modified with the introduction of a new slit (58.4 microns) and of the voltage output (6.5 v) has also been increased. The resolution has been improved from 2.39 mm to 0.59 mm. Of this study, we have examined 20 patients submitted to extracapsular cataract extraction with intraocular lens implantation (ECCE + IOL). The patients have been divided in two groups, according to the surgical technic used: "can-open" and intracapsular. Each patient have been submitted before surgery and 1 week after to an ophthalmologic examination, paquimetry and anterior segment fluorophotometry. The permeability coefficient (PAC) increases with the duration of surgery and when using "can-opener" instead of endocapsular.

Aged↗
PubMed1990

[Fluorophotometry of the vitreous body in diabetics without retinopathy or with minimal retinopathy].

Vitreous fluorophotometry using the Fluorotron Master, was performed on the two eyes of 56 diabetics patients 45,65 year-old +/- 14,91 (mean +/- S.D.), duration of diabetes was 15,14 years +/- 9,17; and on one eye of 17 normal subjects 39,18 years old +/- 11,19. According to biomicroscopic and angiographic examinations, only diabetic subjects with either no or microaneurysmal retinopathy were included. Three groups of right and three groups of left eyes were made: Groups 1: no retinopathy (28 right eyes, 27 left eyes); Groups 2: 1 to 5 microaneurysms (11 right eyes, 20 left eyes); Groups 3: greater than 5 microaneurysms (11 right eyes, 9 left eyes) For the two eyes, posterior vitreous penetration ratio increased with the degree of retinopathy. In the eyes without retinopathy (Groups 1), the penetration ration is not statistically different from the normal subjects; it was the opposite for the eyes with microaneurysmal retinopathy (Groups 2 et 3). The results indicated a breakdown of the blood-retinal barrier only when clinical diabetic retinopathy was present. The relation between fluorophotometric evaluation and the degree of retinopathy showed that vitreous fluorophotometry can be useful in the follow-up of diabetic subjects.

Adolescent↗
PubMed1993

Permeability of the blood-retinal barrier and the blood-aqueous barrier in type I diabetes without diabetic retinopathy: simultaneous evaluation with fluorophotometry.

For the evaluation of a possible malfunction of the blood-retinal barrier (BRB) and the blood-aqueous barrier (BAB) in type I diabetes without manifest angiopathy after i.v. injection of sodium fluorescein, the permeability of the BRB (P) and the permeability coefficient of the BAB [P(a)] were simultaneously determined by fluorophotometry in 34 eyes of 34 type-I diabetics [hemoglobin (Hb)A1c = 6.6% +/- 0.9%] without retinopathy whose age ranged from 19 to 38 years (mean, 30.5 +/- 5 years); the diabetes duration was between 5 and 18 years. Fluorescein angiography was performed to exclude nonperfused areas. In all, 34 eyes of 34 healthy volunteers whose age ranged between 23 and 34 years (mean, 28.5 +/- 3.3 years) served as controls; in this group, fluorophotometry was performed twice to evaluate reproducibility. The mean BAB permeability coefficient in diabetics [P(a) = 5.3 +/- 1.8 x 10(-4)/min] was significantly increased (P = 0.00003) as compared with control values [P(a) = 3.7 +/- 0.7 x 10(-4)/min]; BRB permeability in diabetics (P = 3.2 +/- 1.4 x 10(-7) cm/s) was raised, with this elevation being of lower significance (P = 0.019; controls, P = 2.6 +/- 0.7 x 10(-7) cm/s). We found a decrease in BRB permeability depending on diabetes duration (r = -0.15; P = 0.007) that was not significant in the BAB (r = -0.1; P = 0.24). No correlation was found to exist between permeability and hemoglobin (Hb)A1c values either in the BAB or in the BRB. The reproducibility in controls was 9% in BRB determinations and 12% in BAB measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Effect of topical 0.5% timolol on tear flow in patients with primary open-angle glaucoma as assessed by fluorophotometry.

The question as to whether or not topical medication with beta blockers causes a decrease in tear production remains unanswered. Earlier studies using filter-paper strip tests have yielded contradictory results. In the present study, computerized objective fluorophotometry was used to assess the effect of topical medication with 0.5% timolol (b.i.d.; OU) on tear volume and tear production in 24 consecutive patients with bilateral primary open-angle glaucoma. Tear-film fluorophotometry was performed before treatment as well as at 7 days, 14 days, and 4-7 months after the onset of treatment. The results showed that by 7 days after the initiation of timolol treatment, both tear volume (-29%, P < 0.01) and tear secretion (-36%, P < 0.01) had decreased significantly. However, at both 14 days and 4-7 months after the onset of treatment, none of the values differed significantly from those obtained before treatment. Thus, topical antiglaucomatous treatment with 0.5% timolol eye drops leads to a transient decrease in tear production. This effect, however, lasts no longer than 14 days after the beginning of treatment.

Administration, Topical↗