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A report on three patients with illustrations of their visual anomalies following light coagulation for their CSR disease is presented. The correspondence of the phenomena illustrated with the ophthalmoscopically visible fundus changes prove their objective origin.
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The blue field entoptic phenomenon (BFE), which allows the observation of one's own leukocytes flowing in macular retinal capillaries, was used to predict postoperative macular function in 136 consecutive patients undergoing uncomplicated cataract operation. The results were compared to those obtained with three commonly used tests: two-light discrimination, color perception, and the Purkinje vascular entoptic phenomenon. All four tests identified a nearly equal number of the good maculae (visual acuity 20/40 of better) ranging from 87% for the two-light discrimination test to 94% for the BFE test. However, the tests varied greatly in predicting poor macular function (visual acuity 20/50 or worse). The BFE test identified more than 75% of the poor maculae; the Purkinje vascular entoptic test and the two-light discrimination test, only 22%; and the color perception test, 11%. A positive response to the BFE test indicated a .98 probability of good macular function; a negative response indicated a .82 probability of poor macular function, predictions that were better than the other three tests or their combination.
The entoptic phenomenon of the flying corpuscles (FLC) consists of the perception of one's own leukocytes flowing in the perifoveal capillaries. A method has been developed to investigate the type of motion of the FLC, their relative number and speed, and their distribution over the central visual field. The results in 38 patients with disease affecting the macula correlated well with the clinical findings obtained by ophthalmoscopy, visual field tests, and fluorescein angiography. The test is noninvasive, inexpensive, easy to perform, and provides information on the perifoveal retinal circulation and on macular function.
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Entopic perception of the central choriocapillaris is documented by personal experience. Seen in this manner, the choriocapillaris appears due to circulatory conditions as a wavy convolute of fresh capillaries whose paths are paralleled by numerous, irregularly distributed, round, black structures. The latter have been presumed to be corpuscles, i.e. erythrocytes, and can be seen entopically as single rows of radial capillaries. Histological studies have shown, however, that these rows of erythrocytes are not always isolated; they have also been found in the choriocapillaris in clusters of rows. Moreover, analogously to the lack of entopic perception of erythrocytes in the retinal vessels in Purkinje's images, the erythrocytes of the choriocapillaris may likewise not be perceived for physical and optical reasons. Therefore the round, black formations are not entoptically perceivable erythrocytes of the choriocapillaries but can only originate in the circular network of the central choriocapillaris. Light directed experimentally into the eye and focussed on the choriocapillaris through a narrow slit positioned nasally leads via reflection to stimulation of the retina from outside to inside and so to entoptic perception of the choriocapillary network. Closer analysis of entoptic perception of the choriocapillaris is significant in view of its heuristic value.
Visually evoked cortical potentials closely related to the appearance and disappearance of Haidinger's brushes were obtained in response to onset and offset of rotation of plane-polarized blue light. The method provides a means of investigating macular function in man; it is fairly independent of ocular opacities and relates, for the first time, entoptic phenomena to those evoked by extrinsic light stimulation.
The author reviews the literature on hallucinations that occur as a result of acute and chronic administration of cocaine. He examined the phenomenology of cocaine hallucinations in a group of 85 recreational cocaine users, 15 of whom reported hallucinatory experiences in visual, tactile, olfactory, auditory, and gustatory modalities. He discusses a new phenomenon of "snow lights" in terms of initiating a progression of symptoms leading to the classic "cocaine bugs." He also points out the similarity of cocaine hallucinations to entoptic phenomena and migraine hallucinations, which suggests a common mechanism of action based on CNS excitation and arousal.
Entoptic visualisation of cataract is a simple technique to use. Retro-illumination photography demonstrates that it can also be accurate. The optics of the methods used are discussed.
A measurement system for macular blood flow using the blue field entoptoscope and a microcomputer was devised by Riva & Petrig in 1980. However, there have been difficulties in applying their system to some clinical cases, especially when subjects are aged and their responses are not reliable. A modified method suitable even for such cases is presented.
Blood circulation in the central retina was examined in 30 eyes suffering from glaucoma, using the entoptic phenomenon to count leucocytes travelling through the retinal capillaries in the macula area. Two measurements were taken for each eye at different intraocular pressure levels and the results were compared with each other. They showed that reduction of an originally high intraocular tension level significantly increased the blood flow. In a control group of healthy eyes in a similar group of patients insignificant changes in blood flow were recorded. There was thus a direct linear relationship between reduction of intraocular pressure and relative increase in blood flow with a strongly positive correlation (r = 0,74). Hence an effective autoregulation of blood flow in relation to changes in intraocular pressure could not be demonstrated.
The Purkinje vascular entoptic test is a test of macular function which employs a light directed through the sclera illuminating the fundus. This light casts shadows of retinal blood vessels on to posterior pole photoreceptors. When the light source is moved, a patient with a good macular function should be able to see a negative image of his or her retinal blood vessels. We evaluated the Purkinje test in eyes with clear ocular media. A bright 3.5 watt halogen rechargeable transilluminator was used instead of a pen torch as previously described. Sixty-eight patients (129 eyes) attending a diabetic eye clinic, were tested. The test correctly identified 91% of eyes with good macular function and 77% of eyes with poor macular function (visual acuity 6/24 or poorer). If a vascular pattern was seen, it was probable (0.89) that good macular function was present. If no vascular pattern was seen, it was probable (0.80) that the eye had poor macular function (chi 2 = 60.14, P = < 0.001). Our results were superior to those previously reported. We attribute the increased accuracy of our test to the brighter light source used.
A series of 54 non-myopic aphakic eyes with no signs of posterior vitreous detachment and 63 non-myopic aphakic eyes with various stages of posterior vitreous detachment was followed-up for a period of 6 months to 6 years. Over half of the eyes with no vitreous detachment when first examined developed various stages of posterior vitreous detachment during the follow-up period; in 10 eyes this was accompanied by entopsies with or without photopsies and three eyes developed five new retinal tears. In over half of the eyes with partial vitreous detachment when first examined, the vitreous detachment continued to progress causing retinal detachment in one eye. Late vitreous detachment in non-myopic aphakia or the completion of a partially-detached vitreous could account for the higher incidence of retinal tears in this group of eyes.
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A simplified method of recording and analyzing amblyopic and strabismic examinations is presented. With this new form, the average practitioner is provided with a relatively standardized set of tests in a logical, organized sequence. Programming the patient's responses into meaningful categories facilitates the formation of a differential diagnosis and also provides valuable insight into the eventual outcome of each case.
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