To study the effects of the new aldose reductase inhibitor tolrestat on diabetic retinopathy, 31 diabetic patients with various degrees of retinopathy were randomly assigned to either tolrestat (200 mg once daily) or placebo treatment for six months. Separate morphological features of diabetic retinopathy were assessed by fundus photography and fluorescein angiography before and at the end of the study. The results showed some amelioration of clinical signs of diabetic retinopathy during aldose reductase treatment. Hard exudates, intraretinal hemorrhages and focal fluorescein leakage increased on average in the placebo and decreased in the tolrestat group. The difference was statistically significant for focal fluorescein leakage only. The permeability of the blood retinal barrier was determined by vitreous fluorophotometry before and at the end of the study. No change in permeability values was found.

Administration, Oral↗

PubMed1992

Effect of morphological abnormalities on blood retinal barrier permeability in diabetic retinopathy.

The morphological base for the impaired function of the blood retinal barrier was studied in 50 eyes of 10 insulin dependent and 21 non-insulin dependent patients with various levels of diabetic retinopathy. The permeability of the blood retinal barrier (PBRB) was determined by vitreous fluorophotometry with correction for autofluorescence, lens transmission and non-protein bound plasma fluorescein concentration. Morphological abnormalities of diabetic retinopathy assessed by fundus photography and fluorescein angiography were individually scored on a decimal scale and related to the PBRB by multiple regression analysis. The PBRB was not correlated to morphological abnormalities of non-proliferative retinopathy [(1) microaneurysms, (2) hard exudates, (3) soft exudates, (4) intraretinal hemorrhages, (5) fluorescein leakage, and (6) capillary closure, p greater than 0.3]. The PBRB was correlated to morphological abnormalities of (pre)proliferative retinopathy [(1) intraretinal microvascular abnormalities (SIRMA) and (2) new vessels (Sneo): PBRB = A+B.SIRMA + C.Sneo with PBRB in nm/sec, A = 1.5 +/- 0.5, B = 0.9 +/- 0.2 and C = 1.7 +/- 0.4, R2 = 0.65, p less than 0.0001]. It can be concluded that the increased blood retinal barrier permeability in diabetic patients is mainly due to (pre)proliferative abnormalities and not to non-proliferative abnormalities.

Blood-Retinal Barrier↗

PubMed1991

Epithelial permeability in corneal grafts by fluorophotometry.

The epithelial permeability to fluorescein of 27 clear corneal grafts in 23 patients was determined by fluorophotometry at greater than 1 year after penetrating keratoplasty (PKP) so as to study the recovery of corneal epithelial function. The mean epithelial permeability of the corneal grafts did not differ significantly from that of normal corneas (0.042 +/- 0.016 and 0.038 +/- 0.017 nm/s, respectively; P greater than 0.3). Multiple linear regression analysis showed that permeability correlated with recipient age but not with donor age (permeability increase, 0.00054 nm/s per year; r = 0.6, P less than 0.005 and r = 0.1, P greater than 0.5, respectively). These results indicate that corneal grafts can regain a normal epithelial barrier function and that recovery of epithelial function is better in young than in old recipients.

Adult↗

PubMed1990

Corneal autofluorescence in diabetic and penetrating keratoplasty patients as measured by fluorophotometry.

At first it was verified that the major part of the fluorophotometer signal obtained when measuring corneal autofluorescence originated from fluorescence and not from scatter of excitation light at the corneal surface. The minimum percentage of the signal which can be attributed to fluorescence was determined using a fluorescence blocking filter placed in the excitation and fluorescence light path, respectively. The minimum percentages in two healthy controls, two diabetic patients and two patients after penetrating keratoplasty ranged from 75% to 93% (mean 84%). Then the corneal autofluorescence was determined in 22 healthy controls, 18 non-insulin-dependent diabetes mellitus (NIDDM). 23 insulin-dependent diabetes mellitus (IDDM) and 21 penetrating keratoplasty patients in order to detect a possible difference in autofluorescence as a result of diabetes or penetrating keratoplasty. The means of the corneal peak autofluorescence values in the NIDDM, IDDM and penetrating keratoplasty patient groups were significantly higher than that in the healthy control group (mean values in ng equivalent fluorescin ml-1: 18.0 +/- 4.2 S.D., 20.6 +/- 5.1 S.D., 17.9 +/- 5.5 S.D. and 13.7 +/- 3.7 S.D., respectively; P less than 0.01). The mean values in the NIDDM and IDDM patients did not differ significantly (P = 0.09). The autofluorescence values were independent of age in all four groups (linear correlation coefficient: r less than 0.47). The corneal peak autofluorescence was linearly correlated with the diabetes duration in the NIDDM and IDDM patients [r = 0.6, P = 0.02; increase: 0.36 ng equiv. fluorescein ml-1 yr diabetes-1]. Our results show that corneal autofluorescence is an easily obtained parameter which can be of assistance in evaluating corneal metabolism.

Adolescent↗

PubMed1989

Blood retinal and blood aqueous barriers in diabetics by fluorophotometry.

The permeability of the blood retinal barrier (PBRB) and the diffusion coefficient into the anterior chamber (kd) in 20 insulin dependent (ID) and in 11 non-insulin dependent (NID) diabetics with various degrees of retinopathy were determined by fluorophotometry with a 25% accuracy. The difference of PBRB and the kd values between the NID and the ID patients was not significant (p greater than 0.05 and p greater than 0.22). The mean PBRB and the mean kd values differed significantly from those of a healthy population (p less than 0.0013 and p = 0.025). A significant correlation was established between PBRB and diabetes duration (r = 0.55; p less than 0.01) but not between PBRB or kd values and metabolic control (HbAl) (p greater than 0.5) or creatinine clearance (p greater than 0.5). The time integrals of unbound plasma fluorescein in the diabetics between the time of injection and 1 hour later were comparable with those of healthy controls. The difference between the mean PBRB value of diabetics with advanced retinopathy and that of a healthy population was significant (p less than 0.003) but the difference for the mean values of diabetics with no or minimal background retinopathy was not (p greater than 0.2), indicating that PBRB values do not increase to an abnormal level while signs of diabetic retinopathy are absent on fluorescein angiography.

Age Factors↗

PubMed1988

Corneal epithelial permeability after instillation of ophthalmic solutions containing local anaesthetics and preservatives.

The effect of the local anaesthetics oxybuprocaine (OBu) and tetracaine (Tetra) and the preservatives chlorhexidine (CH) and benzalkonium chloride (BAK) on corneal epithelial permeability was studied by fluorophotometry in normal human eyes. Five instillations of one drop ophthalmic solution of the compounds were administered to one eye at 2-minute intervals; a control solution was instilled into the fellow eye. The increase in corneal epithelial permeability, expressed as the permeability ratio between the treated and control eye, was not significant after instillation of the anaesthetics. The preservatives and the combination OBu + CH increased corneal epithelial permeability significantly (P less than 0.05). OBu + BAK and Tetra + BAK increased permeability to a far greater extent (P less than 0.005).

Adult↗

PubMed1988

Corneal epithelial permeability and daily contact lens wear as determined by fluorophotometry.

The condition of the corneal epithelium of 57 non-, 18 soft-, 29 gas-permeable- and 26 hard contact lens-wearing eyes was investigated by fluorophotometric determination of the corneal epithelial permeability. The mean permeability values for non-, soft-, gas-permeable- and hard contact lens-wearing eyes were 0.040 nm/s +/- 0.017 SD, 0.024 nm/s +/- 0.009 SD, 0.028 nm/s +/- 0.017 SD and 0.044 nm/s +/- 0.020 SD, respectively. The mean permeability values for soft and gas-permeable contact lens-wearing eyes were significantly lower than that for non contact lens-wearing eyes (-40%, p less than 0.001 and -30%, p less than 0.005); no significant difference was found between the mean values for hard and non contact lens-wearing eyes (p = 0.38).

Adolescent↗

PubMed1987

Plasma fluorescein decay determination during fluorophotometry.

Two useful methods for determination of the decay curve of non-protein bound fluorescein (NPBF) in plasma up to 1 hour after intravenous fluorescein injection are described and evaluated. The course of NPBF is approximated in method 1 by a sum of two exponential decay functions and in method 2 by a power of time function. The parameters in these functions are calculated with the use of concentration values measured in two blood samples taken at about 5 min. and 60 min. after injection. Calculations in method 1 include the amount of fluorescein injected. The accuracy of each method was evaluated in 7 volunteers by measuring NPBF concentration in 15-28 blood samples taken after fluorescein injection at intervals of 5 min. or less. The mean relative deviation between calculated and measured concentration values amounted to 9.2% +/- 4.3 SD and 12.7% +/- 4.5 SD for method 1 and 2, respectively. The time integral of NPBF concentration in plasma up to one hour after injection was calculated according to the results of both methods and compared with integral values obtained by linear interpolation between concentration values measured in the 15-28 plasma samples. The mean relative deviation for the 7 volunteers amounted at 15 min. to 2.8% and 17% and at 60 min. to 11% and 18% for method 1 and 2, respectively. The maximal difference between the blood-retinal barrier permeability value for NPBF calculated with and without taking glucuronation into account was estimated to be 20% for an average glucuronation percentage of 70% or less.

Adolescent↗

PubMed1987

A simple method for determination of corneal epithelial permeability in humans.

A simple method for the determination of human corneal epithelial permeability to fluorescein is presented. The method consists of applying a 1% sodium fluorescein solution to the cornea for 8 minutes by means of an eye bath, rinsing the eye, and measuring corneal fluorescence by fluorophotometry. The permeability value is calculated from the corneal fluorescein concentration immediately after the bathing period. Mean permeability value determined in 86 eyes of 46 volunteers aged 15 to 67 years (mean 30.9 years) was 0.038 nm/s +/- 0.017 SD. No significant correlation with age was found (corr. coeff. = 0.17, P = 0.28). The reproducibility was within 10%.

Adolescent↗

PubMed1985

In vivo assessment of lens transmission for blue-green light by autofluorescence measurement.

A simple quantitative and reproducible method for evaluating lens transmission (lambda = 490 and 530 nm) is described. It is based on the measurement of autofluorescence in the anterior and the posterior part of the lens by means of a fluorophotometer, assuming an about equal fluorescence quantum efficiency in both parts. Consequently any difference in fluorescence between both parts can be attributed to a loss of exciting and fluorescent light in the lens. For both wavelengths, the average lens transmission is determined by this method in a normal population as a function of age.

Aged↗