Bent Krogsaa

THE BLOOD‐RETINAL BARRIER PERMEABILITY IN DIABETIC PATIENTS

By the of aid an extended corpus vitreum fluorophotometric technique, the blood‐retinal barrier permeability for fluorescein was studied in diabetologically well characterizied patients with insulin dependent diabetes mellitus. The method, which involves simultaneous determination of the fluorescein concentration in corpus vitreum and plasma, is described and discussed. A clear correlation was found between the degree of retinopathy and permeability (P). Patients with normal visus, ophthalmoscophy, fundus photo and fluorescence angiography exhibited P‐values of 1·10−7 cm·sec−1. This was similar to P‐values found in normal volunteers. Simplex retinopathy without macular oedema showed values of 2.5·10−7 cm·sec−1 while simplex retinopathy with macular oedema showed P‐values of 10·10−7 cm·sec−1.

Clinical course and prognosis of pseudotumor cerebri. A prospective study of 24 patients.

ABSTRACT— In a prospective study, 24 consecutive patients with pseudotumor cerebri were followed for an average of 49 months with regular neurologic and ophthalmologic examinations. At the first examination the intracranical pressure was between 18 and 45 mm Hg; several patients had pressure waves up to 70 mm Hg and decreased conductance to cerebrospinal fluid outflow. In the majority, medical treatment, usually with diuretics and acetazolamide, induced a rapid relief of symptoms, but about 25% had a more protracted disease course with persistent headache, asthenia and memory disturbances interfering with daily life. Five patients required a shunt operation. Chronic changes of the optic disc developed in nearly half the patients, and one had optic atrophy and severe visual impairment. Repeated measurements of the intracranial pressure and conductance to cerebrospinal fluid outflow showed that abnormalities can persist for a long time, even in cases without symptoms of intracranial hypertension.

FLUORESCEIN IN HUMAN PLASMA IN VITRO

A method to determine fluorescein in human plasma is described. By aid of ultrafiltration a separation between fluorescein bound to plasma proteins and fluorescein free in the water is obtained. Both fractions are quantitated. Fluorescein is bound to plasma proteins. The protein binding is reversible, not sensitive to practically appearing changes in pH, temperature and gas tensions. For a normal person it appeared that at a total plasma concentration between (10‐6–10‐4) g·ml‐1 approximately 15% was free while at a total concentration of 10‐3 g·ml‐1 45% was free, pointing towards a limited amount of protein binding sites.

The blood-retinal barrier permeability in essential hypertension.

In a series of 8 patients with recently discovered moderate essential hypertension the blood‐retinal barrier permeability to fluorescein was determined by aid of quantitative vitreous fluorophotometry before and after normalization of the systemic blood pressure. The permeability before medical treatment was 1.69·10‐7 cm/sec (± SEM = 0.14) and after medical treatment and normalization of the blood pressure 1.27·10‐7 cm/sec (± SEM = 0.12), corresponding to the permeability in a normal population. Thus the blood‐retinal barrier permeability is pathologically increased even in moderate degrees of essential hypertension, but this increase in permeability is reversible.

Photometric oculometry. II. Measurement of axial ocular distances with slit-lamp microscopy. Clinical evaluation, and comparison with ultrasonography.

Photometric oculometry is a slit‐lamp technique, which makes possible an estimation of intraocular axial distances and axial length. The technique is based on a transformation of a sagittal slit‐lamp movement into intraocular axial distances when the slit‐lamp focal plane is moved in the optical axis from retina to cornea. Determination of the axial length in 50 eyes (refractive range +4.75 to −5.25 D) showed that the axial length varied from 21.9mm in hypermetropic eyes to 26.0 mm in myopic eyes, with the emmetropic eyes being approximately 24 mm. A comparison of intraocular axial distances determined by photometric oculometry and by ultrasonography on a small series of eyes showed no significant differences between the axial length, the length of the vitreous body, and the lens thickness, whereas a significant difference between the anterior chamber depth was observed (photometry giving slightly larger values than ultrasound).

Transient transport across the blood-retina barrier.

A mathematical model of the transport of fluorescein across the blood-retina barrier in the transient state and the subsequent diffusion of fluorescein in the vitreous body is presented. The function of the barrier is lumped in a single parameter—the permeability. The sensitivity of this parameter due to changes in the other parameters of the model is given. This establishes the foundation for the quantitative assessment of the barrier function through vitreous fluorophotometry.

Breakdown of the blood-retinal barrier in multiple sclerosis measured by vitreous fluorophotometry

Abstract Periphlebitis retinae in multiple sclerosis appears as transitory cellular infiltrations around veins in an otherwise normal retina. Similar cellular infiltrations have been found around veins in the central nervous system. In the present study the blood‐retinal barrier has been investigated by vitreous fluorophotometry. Eight multiple sclerosis patients with actual periphlebitis retinae and 9 patients with previous but not active periphlebitis retinae were included in this study. Abnormal leakage of fluorescein was manifest in the group of multiple sclerosis patients with periphlebitis retinae. Permeability (1.8 ± 0.2 times 10‐7 cm/sec; mean ± SEM) but not in the control group as a whole permeability (1.3 ± 0.1 times 10‐7 cm/sec; mean ± SEM) compared to 17 normals (permeability 1.1 ± 0.005). It is thus concluded that breakdown of the blood‐retinal barrier may be transitory when connected with periphlebitis retinae in multiple sclerosis.

Ophthalmologic prognosis in Benign Intracranial Hypertension

Abstract In a prospective study twenty patients with benign intracranial hypertension, 15 females and five males with mean age 34 years (range 12–61 years), were followed up from 12 to 61 months (mean 22 months). Initially all patients showed marked papilledema, normal visual acuity, considerable enlargement of the blind spot area, and significantly delayed pattern reversal visual evoked potentials.

PHOTOMETRIC OCULOMETRY. I: An analysis of the optical principles in slit-lamp fluorophotometry

The optical principles of slit‐lamp fluorophotometry are analysed by aid of a mathematical model of the optical system. The analysis forms the theoretical basis for a slit‐lamp technique called photometric oculometry, which makes possible an estimation of intraocular axial distances and axial length. The technique is based on a calculation ‐ by aid of a mathematical model of the eye — of the ratio between intraocular movement of the slit‐lamp focal plane and corresponding movement of the slit‐lamp. Intraocular axial distances can be calculated by aid of this ratio and a direct measurement of the slit‐lamp movement when the focal plane is moved in the optical axis from retina to cornea. These items are prerequisites for a quantitative determination of the blood‐retinal barrier permeability to fluorescein during vitreous fluorophotometry.

Carriers of X-linked retinitis pigmentosa* A fluorophotometric determination of the permeability of the blood-retinal barrier

The blood-retinal barrier permeability to fluorescein was studied in a single family with X-linked retinitis pigmentosa by an elaborate vitreous fluorophotometric method. Affected males showed a ten times increase of permeability compared with normals. In a group of seven obligate carriers the mean permeability was significantly increased by 45% compared with the mean permeability in a group of normals. Five of the seven carriers had permeabilities higher than the normal mean permeability + 2 SD, while two carriers had a permeability within the normal mean +/- 2 SD. Thus, this study supported that carriers of X-linked retinitis pigmentosa show deterioration of the blood-retinal barrier. However, the phenomenon is not present in all carriers and the permeability cannot be used as a completely safe indicator of the carrier state.