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PubMedDate not supplied

[Chromatopsia].

A total of 277 chromatopsia cases (0.09 percent of the total number) are analyzed, including erythropsia, xanthopsia, cyanopsia, chloropsia, and polychromatopsia. True chromatopsia and chromatopsia due to staining of optic media of the eyes were distinguished and an attempt to explain this entoptic phenomenon made. True chromatopsias are related to depression of stimulation of the optic nerve route.

Adult↗
PubMed1998

An optical explanation of the entoptic phenomenon of 'clouds' in posterior vitreous detachment.

The purpose of this work is to investigate in detail the optics of the shadow cast by vitreous opacities and its effects in the perception of related entoptic phenomena. The optics of the eclipse has been used as a model. The various parameters affecting the shadow, i.e. the diameter of the opacity, its distance from the retina and the overall distance between the pupillary plane and the retina, have been taken into account in the calculations. A mathematical function has been derived and curves defining the density of the penumbra have been plotted for various distances of an opacity from the retina. An area of uniform partial illumination of the retina behind the opacity has been defined, outside of which the density of the penumbra falls rapidly. It is concluded that the sensation of 'cloud' or 'smoke' reported by the patient stems from this uniform area of penumbra behind the opacity, whose extent depends on the above mentioned parameters. Thus, the optics of the eclipse explains this entoptic phenomenon. Of course, 'clouds' can also be due to semi-transparent vitreous floaters.

Humans↗
PubMed2006

Scanning laser entoptic perimetry for the detection of visual defects associated with diabetic retinopathy.

AIM: To determine the sensitivity and specificity of entoptic perimetry for diagnosing diabetic retinopathy at all levels of severity. METHODS: A prospective clinical study at the Shiley Eye Center, University of California, and San Diego. 30 patients with photographically documented diabetic retinopathy and 24 controls with a similar age distribution. Sensitivity and specificity of entoptic perimetry were computed for detecting clinically significant macular oedema within the central 120 degree radius of the fovea compared to fundus photographs. RESULTS: Entoptic perimetry can detect clinically significant diabetic retinopathy with a sensitivity of 0.88 and specificity of 1.00. Entoptic perimetry can detect the earliest stages of diabetic retinopathy with a sensitivity of 0.86. CONCLUSION: Scanning laser entoptic perimetry is an effective tool for detecting visual function loss caused by diabetic retinopathy.

Aged↗
PubMed2004

Marius Tscherning (1854-1939): his life and work in optical physiology.

BACKGROUND: This article is based on Tscherning's papers, scientific protocols and letters and the many original instruments kept in the Medical History Museum in Copenhagen, Denmark. HISTORY: In 1884, after his thesis concerning the frequency of myopia in Denmark, Tscherning became adjunct director of the ophthalmological laboratory at the Sorbonne University in Paris. He was called back to Denmark in 1910 and appointed professor of ophthalmology and head of the Eye Department, Rigshospitalet. He continued to work scientifically as emeritus from 1925. ACHIEVEMENTS: Tscherning published about 100 scientific papers, mainly concerning optical physiology (i.e. the aetiology of myopia, entoptic phenomena, Purkinje pictures, the polygonal pattern provoked by corneal rubbing, etc.). He studied the law of Listing and projections depending on torsion of the eye and invented the ophthalmophacometer, which measures the changes that occur in the front and back curvatures of the crystalline lens during accommodation. Tscherning also studied aberration and calculated and constructed forward bulging periscopic (punctal) spectacle lenses. In addition, he studied colour sense, dark vision and adaptation.

Denmark↗
PubMed2000

Entoptic perimetry screening for central diabetic scotomas and macular edema.

OBJECTIVE: The aim of this study was to compare entoptic perimetry, using conventional television, to Amsler grid and patient-reported visual loss for the detection of functional diabetic maculopathy and macular edema. DESIGN: Observational case series. PARTICIPANTS: A single eye from each of 104 consecutive patients with diabetes in an academic retina clinic. INTERVENTION: Each eye was screened by Amsler grid, entoptic perimetry, and Humphrey 10-2 threshold visual field testing (HVF 10-2; Humphrey Instruments Inc., San Leandro, CA) in random order. Eyes were then examined clinically. MAIN OUTCOME MEASURES: The presence or absence of new visual decline since the patient's last clinical examination, the presence or absence of central visual field abnormalities using an Amsler grid, entoptic perimetry, HVF 10-2, and the presence or absence of clinically significant macular edema (CSME). RESULTS: The sensitivities and specificities for the detection of central diabetic scotomas as evidenced by HVF 10-2 abnormalities were: subjective impression, 31 of 90 eyes (34.4%) and 11 of 14 eyes (78.6%); Amsler grid, 29 of 90 eyes (32.2%) and 13 of 14 eyes (92.9%); and entoptic perimetry, 58 of 90 eyes (64.4%) and 11 of 14 eyes (78.6%). Entoptic perimetry was statistically more sensitive than both subjective impression (P < 0.001) and Amsler grid (P < 0.001), but the specificities were statistically indistinguishable. The sensitivities and specificities for the detection of CSME were: subjective impression, 6 of 24 eyes (25.0%) and 52 of 80 eyes (65.0%); Amsler grid, 9 of 24 eyes (37.5%) and 59 of 80 eyes (73.8%); and entoptic perimetry, 17 of 24 eyes (70.8%) and 44 of 80 (55.0%) eyes. These results are also statistically significant, with entoptic perimetry being more sensitive and less specific than both subjective impression (P = 0.007 and P = 0.011, respectively) and Amsler grid (P = 0.008 and P < 0.001, respectively) in this subset of patients. CONCLUSIONS: Entoptic perimetry is 87% more sensitive than the subjective impression of visual decline (P < 0.001) and 100% more sensitive than Amsler grid (P < 0.001) for the detection of central scotomas in diabetic patients. For the detection of CSME, entoptic perimetry is 183% more sensitive than subjective impression (P = 0.007) and 89% more sensitive than Amsler grid (P = 0.008). Hence, entoptic perimetry, performed using conventional television, has the potential to be an effective, inexpensive, and widespread adjunct to surveillance examinations for the early detection of diabetic maculopathy.

Adult↗
PubMed1995

Aniseikonia, metamorphopsia and perceived entoptic pattern: some effects of a macular epiretinal membrane, and the subsequent spontaneous separation of the membrane.

Following cryo surgery for retinal hole repair, visual effects in the senior author's eyes were caused by an epiretinal membrane. Subjectively, metamorphopsia was noted, and entoptically perceived radial striae were observed centred near fixation. After subsequent cataract surgery, metamorphopsia was not detectable. Several months later, the centre of the striate entoptic pattern was observed to be centered several degrees from fixation. Concurrently, loss of contrast in the central visual field was noted. In time, both the entoptic pattern and the contrast effects became less visible (contrast improved much faster). The epiretinal membrane had spontaneously separated from the fovea. Repeated measurements of aniseikonia were obtained before cataract surgery, and after cataract surgery both prior to, and after the separation of the epiretinal membrane. Inferences are drawn.

Aniseikonia↗
PubMed1991

Macular retinal capillary hemodynamics in diabetic patients.

Macular retinal capillary hemodynamics was evaluated in 39 nonhypertensive insulin-dependent diabetic patients and 24 age-matched control subjects using the blue field entopic simulation technique. A statistically significant 25% increase in macular capillary flow velocity was observed among the diabetic eyes along with a 37% decrease in the density of the entoptically perceived leukocytes. When the eyes of diabetic patients were graded according to the modified composite scale of Klein et al, capillary flow velocity was elevated in the group without retinopathy as well as in those with mild background retinopathy and those with preproliferative or proliferative retinopathy. The density of the entopically perceived leukocytes was more severely reduced in those with retinopathy than in those without retinopathy but was poorly correlated with the composite grading scale. These results are consistent with the concept that in diabetes, capillary obstruction, either transient or permanent, may focally occur within the retina associated with vasodilation in the adjacent microvasculature because of relative tissue hypoxia.

Adult↗
PubMed1993

Effect of aging on retinal macular microcirculation: a blue field simulation study.

PURPOSE: Structural changes in the retina are known to occur with aging. This study was performed to investigate whether aging also affects the retinal macular microcirculation. METHODS: Healthy volunteers with ages ranging from 20 to 78 years (mean +/- SD, 49 +/- 19 years) were included in this study. The retinal macular microcirculation was assessed with the blue field simulation technique, based on the blue field entoptic phenomenon. Subjects were asked to match the velocity and density of computer-simulated particles displayed on a screen with those of their entoptically observed leukocytes. Ten matching trials were performed, and an average leukocyte velocity and density were calculated. RESULTS: Significant negative linear correlations were observed between velocity and age (P = 0.0001) and density and age (P = 0.009). Older subjects (50 to 78 years of age) had a significantly slower velocity (0.61 +/- 0.21 mm/s) and smaller density (90 +/- 43 particles per field of view) than younger subjects (0.92 +/- 0.12 mm/s and 135 +/- 65 particles, respectively; unpaired Student's t-test, P = 0.001 and P = 0.01, respectively). CONCLUSIONS: These results suggest that, in normal subjects, retinal macular blood flow decreases with age. The 20% decrease in average velocity with age is very similar to the age-related decrease in number of cells observed in the human foveal ganglion cell layer.

Adult↗
PubMed1992

Macular capillary hemodynamic changes associated with Raynaud's phenomenon.

BACKGROUND: Raynaud's phenomenon is an episodic, reversible spasm of the digital arterioles. Previous studies have suggested that Raynaud's phenomenon may be associated with alterations in the ocular circulation. The authors used the blue field entoptic simulation technique to study macular retinal capillary hemodynamics in patients with Raynaud's phenomenon. METHODS: Forty-two volunteers participated in the study: 18 with a connective tissue disease and secondary Raynaud's phenomenon, 8 with a connective tissue disease and no Raynaud's phenomenon, and 16 healthy volunteers. The mean of three blue field entoptic density and velocity measurements was determined before as well as during and 10 minutes after the immersion of one hand in ice water. RESULTS: Patients with severe Raynaud's phenomenon demonstrated a statistically significant 30% decrease in retinal capillary flow during immersion of a hand in ice water (P less than 0.05), which remained 17% reduced (P less than 0.05) for at least 10 minutes after removal. The decrease in capillary flow was not observed in control individuals or in individuals with connective tissue disease who demonstrated minimal or no Raynaud's phenomenon. CONCLUSION: The prolonged reduction in retinal capillary flow observed in subjects with Raynaud's phenomenon is probably caused by retinal arteriolar vasoconstriction and is similar to concurrent arteriolar vasoconstriction reported in other systemic vascular beds. In the retina, the recurrent ischemic episodes may result in dysfunction or injury.

Adult↗
PubMed1986

A comparison of visual function tests in eyes with maculopathy.

Several recently developed tests of visual function, including the Potential Acuity Meter (PAM), laser interferometer (LI), white-light interferometer (WLI), blue field entoptic phenomenon, and focal electroretinogram (ERG) were compared in 81 eyes with clear media and known macular disease. The results indicate that the PAM, the LI, and the WLI overread relative to Snellen acuity. Laser interferometric acuity values differed from Snellen acuity by at least 1.5 octaves in approximately 40% of all eyes, regardless of stimulus size (2, 5, or 8 degrees). Similar results were obtained with the WLI. Agreement with Snellen acuity was better for the PAM, with 91% of eyes falling within 1.5 octaves of Snellen acuity. Blue field and focal ERG results were categorized as normal or abnormal. While not producing Snellen equivalents, abnormal results from the blue field and focal ERG corresponded with poor Snellen acuity (less than 20/40) in 65% and 91% of eyes, respectively. Assuming that media opacities do not prevent adequate retinal stimulation, the present results suggest that the PAM and focal ERG are the most reliable for evaluating macular function when maculopathy is present.

Electroretinography↗