Anterior ischemic optic neuropathy.

Though anterior ischemic optic neuropathy (AION) has been widely reported, it is not fully appreciated as one of the commonest causes of impaired vision in persons past middle age. These patients are not infrequently suspected of having an intracranial tumor. This article reviews the clinical features of AION and discusses its pathogenesis and treatment.

Blood-retinal barrier in eyes with long-standing aphakia with apparently normal fundi.

Vitreous fluorophotometry was used to evaluate the integrity of the blood-retinal barrier in 130 eyes with long-standing aphakia and apparently normal fundi. All patients had undergone intracapsular lens extraction because of senile cataract and had been followed up for approximately one year (group 1) or three years (group 2). Thirty normal eyes served as controls. Thirty minutes or one hour after intravenous administration of fluorescein sodium, 50 of 130 aphakic eyes (32 of 70 group 1 eyes; 18 of 60 group 2 eyes) and three of 30 control eyes were judged abnormal in breakdown of the blood-retinal barrier. In aphakic eyes, the older the age at operation, the higher the incidence of barrier breakdown. These results indicate that the blood-retinal barrier remains disrupted for a longer postoperative period than was previously thought, and that the incidence of barrier breakdown relates to the age at operation. Although these findings reflect subclinical phenomena, they are biologically important.

Indirect funduscopy in a gas filled eye: an observation.

It has been observed that a vitrectomised, gas filled, phakic eye can produce a real, inverted, aerial image of the fundus anterior to the cornea. The optics of this phenomenon are discussed.

Optical quality of the human eye.

1. Optical quality of the eye was measured at eight pupil sizes between 1.5 and 6.6 mm diameter by recording the faint light emerging from the eye; this light was reflected from the bright image of a thin line on the fundus.2. The nature of the fundus reflexion was examined; it was found that the fundus acts very much like a perfect diffuser while retaining polarization.3. Using the result that the fundus acts like a diffuser, the recorded line images were Fourier analysed to provide modulation transfer functions. These functions indicate an optical quality considerably higher than that found in previous physical studies.4. Linespread profiles were then derived from the modulation transfer functions. These profiles are 40% narrower than those of previous physical studies for a 3.0 mm pupil. The narrowest profile occurred with a 2.4 mm pupil.5. Our results demonstrate that physical and psychophysical studies can yield similar estimates of optical quality. The influence of optical factors not common to both techniques is discussed. Evidence for the existence of neural ;image sharpening' mechanisms is reviewed.

Polarized light and the human fundus oculi.

1. Measurements were made of the relative fractions of diffuse and specular reflexions in the fovea and periphery of the human fundus oculi.2. All the light emerging from the eye is scattered or reflected behind the receptors as bleaching the retina affects both fractions equally.3. Bruch's membrane is the most likely surface at which specular reflexion occurs whereas the choroid and sclera are probably involved in scattering.4. Both diffuse and specular components show marked directional effects that vary with wave-length.

DC recording of the human corneofundal potential.

The limitation of an AC technique for the amplification and display of the indirectly recorded human corneofundal potential (CFP)is discussed. A Mingograph M34 with EMT 12 B preamplifiers (Siemens) has been tested with regard to a DC recording of the CFP. With the same purpose the electrical characteristics of two electrode types--a Kaiser lead alloy electrode and a Beckman silver-silver chloride cupped electrode--were examined and a suitable preparation of the skin contact area indicated. Finally the base line stability was evaluated and a comparative study of AC and DC recordings of the CFP presented and subjected to statistical anaylsis.

Effect of pre-exposure fundus temperature on threshold lesion temperatures in the laser-irradiated rabbit retina.

The relationship between pre-exposure fundus temperature and the temperature rise which produces a threshold burn was examined in rabbit eyes exposed to an Argon c. w. laser (4,880 A) for 10 seconds. The posterior pole of the eye was surgically exposed and a 20-micron tip diameter probe was inserted into the ocular fundus to measure temperature rises. The temperature rise for threshold burns linearly increased as preexposure fundus temperature decreased, implying a constant threshold temperature. Threshold temperature was indirectly predicted to be 52.4 degrees C. using a system with an estimated error of plus or minus 1/2 degrees C.

The normal fundus fluorescein angiogram. IV. A classification of the normal fundus fluorescein angiogram based on angiographic findings in clinically healthy subjects and in diabetics without ophthalmoscopically abnormalities.

A comparison of fundus elements in the posterior pole of the eye in a group of 48 clinically healthy subjects and in a group of 17 insulin dependent diabetics showed a significant overrepresentation (P less than 0.05) of hyperfluorescent and hypofluorescent elements among the diabetics, as estimated from serial fundus fluorescein angiograms at 3 examinations during one year. In the diabetics a significant intraindividual variation of hyperfluorescent elements (6/17 eyes) occurred during one year in contrast to the clinically healthy subjects (0/48)-(P less than 0.01). The normal fundus fluorescein angiogram (i.e. in clinically healthy subjects) is characterized by: a wide physiologic variation of the number of hyperfluorescent elements i.e. 0-4 elements or 0-11 elements as assessed with and without a one tailed 10% percentile as an upper limit. Hypofluorescent elements in variable number may occur in 21% (upper limit 10% percentile) or 31% (without an upper limit) of normal eyes. No intra-individual variation of these hyper- and hypofluorescent elements developed during the observation period.

A simple method for screening of children with strabismus, anisometropia or ametropia by simultaneous photography of the corneal and the fundus reflexes.

A simple screening method for detecting strabismus, anisometropia and ametropia in young children by simultaneous photography of the corneal and fundus reflexes with a conventional camera and flashlight is presented. The method is the photographic application of the von Brückner Durchleuchtung test and static skiascopy. The objective document from the external part of the eyes and the face is obtained at the same time. Model photographs with certain gaze deviation angles are presented with the method.