scholarly journals THE VARIABILITY OF INTENSITY DISCRIMINATION BY THE HONEY BEE IN RELATION TO VISUAL ACUITY

1933 ◽  
Vol 16 (5) ◽  
pp. 787-793 ◽  
Author(s):  
Ernst Wolf ◽  
W. J. Crozier
Keyword(s):  
Visual Acuity ◽  
Honey Bee ◽  
Power Function ◽  
Intensity Discrimination ◽  
Frequency Of Occurrence ◽  
Threshold Response ◽  
The Difference

Variation in the determined magnitudes of the difference in brightness between alternating members of a system of stripes requisite for the elicitation of a threshold response in bees shows that the intensity of excitation, as a function of width of stripe and of intensity of illumination, is determined by the intensity of illumination and by the frequency of occurrence of divisions between bright and less bright bars. The variation of ΔI is limited by the intensity of excitation, so that the curves relating P.E. (ΔI/I) have the same form in relation to I as do the curves for ΔI/I. The limiting rule according to which P.E. ΔI is a power function of I for stripes of maximum usable width is departed from more and more markedly, for lower intensities, as narrower stripes are employed.

scholarly journals ON THE VARIABILITY OF CRITICAL ILLUMINATION FOR FLICKER FUSION AND INTENSITY DISCRIMINATION

1936 ◽  
Vol 19 (3) ◽  
pp. 503-522 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
Visual Acuity ◽  
General Problem ◽  
Visual Function ◽  
Visual Discrimination ◽  
Dark Adaptation ◽  
Intensity Discrimination ◽  
The Sun ◽  
Threshold Response ◽  
Independent Variable ◽  
Flicker Fusion

From the data of experiments with bees in which threshold response is employed as a means of recognizing visual discrimination between stripes of equal width alternately illuminated by intensities I1 and I2, it is shown that the detectable increment of intensity ΔI, where ΔI = I2 - I1, is directly proportional to σI2 (I1 being fixed). From tests of visual acuity, where I1 = 0 and the width of the stripes is varied, σI2 = kI2 + const.; here I2 = ΔI, and ΔI/I2 = 1. When the visual excitability of the bee is changed by dark adaptation, λI ≡ kΔI (= k' σΔI) = k'' I + const. For the measurements of critical illumination at threshold response to flicker, σI2 (= σΔI) = k I2 = k' ΔI + const. The data for critical illumination producing threshold response to flicker in the sun-fish Lepomis show for the rods σI2 = K I2 for the cones σI2 = K'(I2 + const.). The data thus indicate that in all these experiments essentially the same visual function is being examined, and that the recognition of the production of a difference in effect by alternately illuminated stripes takes place in such a way that d (ΔI)/d (σI2) = const., and that ΔI is directly proportional to I (or "I2," depending on the nature of the experiment). It is pointed out that the curve for each of the cases considered can be gotten equally well if mean I or σI is plotted as a function of the independent variable involved in the experiment. Certain consequences of these and related facts are important for the treatment of the general problem of intensity discrimination.

scholarly journals ON THE RELATION BETWEEN MEASUREMENTS OF INTENSITY DISCRIMINATION AND OF VISUAL ACUITY IN THE HONEY BEE

1933 ◽  
Vol 16 (5) ◽  
pp. 773-786 ◽  
Author(s):  
Ernst Wolf
Keyword(s):  
Visual Acuity ◽  
Visual Field ◽  
Honey Bee ◽  
Visual Angle ◽  
Constant Level ◽  
Intensity Discrimination ◽  
Direct Test ◽  
Discrimination Power ◽  
Consistent Manner

1. Bees respond by a characteristic reflex to a movement of their visual field. By confining the field to a series of parallel stripes of two alternating different brightnesses it is possible to determine for any width of stripe, at any brightness of one of the two sets of stripes, the brightness of the second at which the bee will first respond to a displacement of the field. Thus the relations between visual acuity and intensity discrimination can be studied. 2. For each width of stripe and visual angle subtended by the stripe the discrimination power of the bee's eye for different brightnesses was studied. For each visual acuity the intensity discrimination varies with illumination in a characteristic, consistent manner. The discrimination is poor at low illuminations; as the intensity of illumination increases the discrimination increases, and reaches a constant level at high illuminations. 3. From the intensity discrimination curves obtained at different visual acuities, visual acuity curves can be reconstructed for different values of ΔI/I. The curves thus obtained are identical in form with the curve found previously by direct test for the relation between visual acuity and illumination.

Comparison of the Effectiveness of Intravitreal Ranibizumab for Diabetic Macular Edema in Vitrectomized and Nonvitrectomized Eyes

2016 ◽  
Vol 236 (2) ◽  
pp. 67-73 ◽  
Author(s):  
Yoshito Koyanagi ◽  
Shigeo Yoshida ◽  
Yoshiyuki Kobayashi ◽  
Yuki Kubo ◽  
Muneo Yamaguchi ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Macular Edema ◽  
Diabetic Macular Edema ◽  
Treatment Option ◽  
Central Macular Thickness ◽  
Intravitreal Ranibizumab ◽  
Corrected Visual Acuity ◽  
The Mean ◽  
The Difference ◽  
Best Corrected Visual Acuity

Purpose: To compare the effectiveness of intravitreal ranibizumab (IVR) for diabetic macular edema (DME) between eyes with and without previous vitrectomy. Procedures: We prospectively assessed the best-corrected visual acuity (BCVA) and central macular thickness (CMT) after IVR for 6 months. Results: There were no significant differences in the baseline BCVA and CMT between both groups. In the nonvitrectomized group (n = 15), the mean changes of BCVA and CMT from baseline to month 6 were significant (p < 0.01). In the vitrectomized group (n = 10), the improvement appeared to be slower, and the mean BCVA improvement was not significant (p = 0.5), although the mean CMT decrease was significant (p < 0.05). There were no significant differences in the mean changes of BCVA and CMT between both groups at 6 months. Conclusions: The difference in the effectiveness of IVR between both groups was not significant. IVR can be a treatment option even for vitrectomized DME eyes.

scholarly journals Outcomes of Femtosecond Laser Assisted Cataract Surgery Performed by Resident and Attending Surgeons

2021 ◽  
Vol 13 (01) ◽  
pp. e26-e31
Author(s):  
Spencer C. Cleland ◽  
Daniel W. Knoch ◽  
Jennifer C. Larson
Keyword(s):  
Visual Acuity ◽  
Femtosecond Laser ◽  
Cataract Surgery ◽  
Retrospective Chart Review ◽  
Dissipated Energy ◽  
Independent Practice ◽  
Postoperative Visual Acuity ◽  
Included Patient ◽  
Duration Of Surgery ◽  
The Difference

Abstract Objective The study aimed to evaluate the safety and efficacy of resident surgeons performing femtosecond laser assisted cataract surgery (FLACS). Methods A retrospective chart review was conducted at the University of Wisconsin-Madison from postgraduate year four residents performing FLACS between 2017 and 2019. Data were also collected from residents performing manual cataract surgery, and attending surgeons performing FLACS for comparison. Recorded data included patient demographics, pre- and postoperative visual acuity, pre- and postoperative spherical equivalent, nuclear sclerotic cataract grade, ocular and systemic comorbidities, intraocular lens, duration of surgery, cumulative dissipated energy (CDE), and intraoperative and postoperative complications. Results A total of 90 cases were reviewed with 30 resident manual cases, 30 resident FLACS cases, and 30 attending FLACS cases. Resident manual (25.5 ± 6.8 minutes) and resident FLACS (17.5 ± 7.1 minutes) cases took a significantly longer time to complete compared with attending FLACS cases (13.6 ± 4.4 minutes; p < 0.001). There was higher CDE in resident FLACS and resident manual cases compared with attending FLACS cases, but the difference was not statistically significant (p = 0.06). Postoperative visual acuity was not statistically different at 1-day and 1-month after surgery among the three groups. Resident FLACS complications, which included one case requiring an intraoperative suture to close the wound, two cases with intraoperative corneal abrasions, two cases with postoperative ocular hypertension, and one case with cystoid macular edema, were not significantly greater than attending FLACS complications (p = 0.30). Conclusion The FLACS performed by resident surgeons had comparable visual acuity outcomes to FLACS performed by attending surgeons, and to manual cataract surgery performed by resident surgeons. However, resident FLACS cases took significantly longer time to complete, and they were associated with a higher CDE and minor complication rate compared with attending FLACS cases. Introducing advanced technologies into surgical training curricula improves resident preparedness for independent practice, and this study suggests FLACS can be incorporated safely and effectively into resident education.

scholarly journals Frequency of deep convective clouds in the tropical zone from 10 years of AIRS data

2013 ◽  
Vol 13 (21) ◽  
pp. 10795-10806 ◽  
Author(s):  
H. H. Aumann ◽  
A. Ruzmaikin
Keyword(s):  
Brightness Temperature ◽  
Frequency Of Occurrence ◽  
Tropical Zone ◽  
Convective Clouds ◽  
The Past ◽  
Atmospheric Window ◽  
Deep Convective Clouds ◽  
Sst Anomaly ◽  
The Difference ◽  
Global Precipitation

Abstract. Deep convective clouds (DCCs) have been widely studied because of their association with heavy precipitation and severe weather events. Changes in the properties of DCCs are likely in a changing climate. Ten years of data collected by Atmospheric Infrared Sounder (AIRS) allow us to identify decadal trends in frequency of occurrence of DCCs over land and ocean. In the past, DCCs have been identified in the thermal infrared by three methods: (1) thresholds based on the absolute value of an atmospheric window channel brightness temperature; (2) thresholds based on the difference between the brightness temperature in an atmospheric window channel and the brightness temperature centered on a strong water vapor absorption line; and (3) a threshold using the difference between the window channel brightness temperature and the tropopause temperature based on climatology. Simultaneous observations of these infrared identified DCCs with the Advanced Microwave Sounding Unit–Humidity Sounder for Brazil (AMSU-HSB) using 183 GHz water channels provide a statistical correlation with microwave deep convection and overshooting convection. In the past 10 years, the frequency of occurrence of DCCs has decreased for the tropical ocean, while it has increased for tropical land. The area of the tropical zone associated with DCCs is typically much less than 1%. We find that the least frequent, more extreme DCCs show the largest trend in frequency of occurrence, increasing over land and decreasing over ocean. The trends for land and ocean closely balance, such that the DCC frequency changed at an insignificant rate for the entire tropical zone. This pattern of essentially zero trend for the tropical zone, but opposite land/ocean trends, is consistent with measurements of global precipitation. The changes in frequency of occurrence of the DCCs are correlated with the Niño34 index, which defines the sea surface temperature (SST) anomaly in the east-central Pacific. This is also consistent with patterns seen in global precipitation. This suggests that the observed changes in the frequency are part of a decadal variability characterized by shifts in the main tropical circulation patterns, which does not fully balance in the 10-year AIRS data record. The regional correlations and anti-correlations of the DCC frequency anomaly with the Multivariate ENSO Index (MEI) provide a new perspective for the regional analysis of past events, since the SST anomaly in the Nino34 region is available in the form of the extended MEI from 1871.

scholarly journals Frequency of deep convective clouds in the tropical zone from ten years of AIRS data

2013 ◽  
Vol 13 (4) ◽  
pp. 10009-10047
Author(s):  
H. H. Aumann ◽  
A. Ruzmaikin
Keyword(s):  
Water Vapor ◽  
Brightness Temperature ◽  
Frequency Of Occurrence ◽  
Tropical Zone ◽  
Convective Clouds ◽  
Atmospheric Window ◽  
Deep Convective Clouds ◽  
Sst Anomaly ◽  
The Difference ◽  
Global Precipitation

Abstract. Deep Convective Clouds (DCC) have been widely studied because of their association with heavy precipitation and severe weather events. To identify DCC with Atmospheric Infrared Sounder (AIRS) data we use three types of thresholds: (1) thresholds based on the absolute value of an atmospheric window channel brightness temperature; (2) thresholds based on the difference between the brightness temperature in an atmospheric window channel and the brightness temperature centered on a strong water vapor absorption line; and (3) a threshold using the difference between the window channel brightness temperature and the tropopause temperature based on climatology. We find that DCC identified with threshold (2) (referred to as DCCw4) cover 0.16% of the area of the tropical zone and 72% of them are identified as deep convective, 39% are overshooting based on simultaneous observations with the Advanced Microwave Sounding Unit-HSB (AMSU-HSB) 183 GHz water vapor channels. In the past ten years the frequency of occurrence of DCC decreased for the tropical ocean, while it increased for tropical land. The land increase-ocean decrease closely balance, such that the DCC frequency changed at an insignificant rate for the entire tropical zone. This pattern of essentially zero trend for the tropical zone, but opposite land/ocean trends, is consistent with measurements of global precipitation. The changes in frequency of occurrence of the DCC are correlated with the Niño34 index, which defines the SST anomaly in the East-Central Pacific. This is also consistent with patterns seen in global precipitation. This suggests that the observed changes in the frequency are part of a decadal variability characterized by shifts in the main tropical circulation patterns, which does not fully balance in the ten year AIRS data record. The regional correlations and anti-correlations of the DCC frequency anomaly with the Multivariate ENSO Index (MEI) provides a new perspective for the regional analysis of past events, since the SST anomaly in the Nino34 region is available in the form of the extended MEI since 1871. Depending on the selected threshold, the frequency of DCC in the tropical zone ranges from 0.06% to 0.8% of the area. We find that the least frequent, more extreme DCC also show the largest trend in frequency, increasing over land, decreasing over ocean. This finding fits into the framework of how weather extremes respond to climate change.

scholarly journals The effect of amblyopia on clinical outcomes of children with astigmatism

2021 ◽  
Vol 13 ◽  
pp. 251584142110408
Author(s):  
Burçin Çakır ◽  
Nilgün Özkan Aksoy ◽  
Sedat Özmen ◽  
Özlem Bursalı
Keyword(s):  
Visual Acuity ◽  
Clinical Outcomes ◽  
Medical Records ◽  
Convergence Insufficiency ◽  
Corrected Visual Acuity ◽  
Ocular Deviation ◽  
The Mean ◽  
The Difference ◽  
Best Corrected Visual Acuity

Background: Amblyopia is more common in children with high astigmatism, but factors contributing to development of amblyopia and visual outcomes are not fully understood. Objective: To evaluate the effect of amblyopia on the clinical outcomes in children with ⩾1.75 diopter (D) astigmatism. Methods: We reviewed the medical records of children with ⩾1.75 D astigmatism with and without amblyopia (amblyopes group and non-amblyopes group). The mean age, gender, amount and type of ocular deviation, presence of convergence insufficiency (CI), stereopsis, time of initial spectacle use and follow-up time, differences in best-corrected visual acuity (VoD) and spherical equivalent (SE) between eyes were assessed and compared between the groups. Best-corrected visual acuity (BCVA), mean SE, astigmatism measurements were assessed and compared between amblyopic, fellow, and non-amblyopic eyes. Results: The records included 68 eyes of 34 children with amblyopia and 56 eyes of 28 children without amblyopia. The mean age, gender, amount and type of ocular deviation, presence of CI, stereopsis, time of initial spectacle use, follow-up time, and the difference in SE did not differ between groups. In amblyopes, exodeviation was more common and statistically greater in near (33 cm) than at distance (6 m) (p = 0.005). The mean BCVA and astigmatism values were statistically different between amblyopic, fellow, and non-amblyopic eyes. Conclusion: A greater near than distance exodeviation and higher mean astigmatism value were found in amblyopic children with astigmatism.

Prospective analysis of visual function changes in patients with dermatochalasis after upper eyelid blepharoplasty

2019 ◽  
Vol 30 (5) ◽  
pp. 978-984
Author(s):  
Meryem Altin Ekin ◽  
Seyda Karadeniz Ugurlu
Keyword(s):  
Visual Acuity ◽  
Contrast Sensitivity ◽  
Visual Function ◽  
Spherical Aberration ◽  
Higher Order ◽  
Rank Test ◽  
Higher Order Aberrations ◽  
Upper Eyelid ◽  
Spatial Frequencies ◽  
The Difference

Objective: To evaluate the changes of visual acuity, contrast sensitivity, astigmatism, and higher order aberrations after blepharoplasty in patients with dermatochalasis. Methods: Two hundred six eyelids of 103 patients with dermatochalasis were prospectively studied. Visual acuity, contrast sensitivity, corneal topography, astigmatism degree, and higher order aberrations were examined and recorded before and at 1 month after upper eyelid blepharoplasty. Change in contrast sensitivity and astigmatism values were determined according to margin reflex distance of patients, which were classified into three following groups: <2 mm, 2–3 mm, and ⩾ 4 mm. A Wilcoxon signed rank test was performed to compare the difference. Results: No significant differences were observed for visual acuity (p = 0.157). The contrast sensitivity of patients significantly increased at all spatial frequencies both under glare and nonglare conditions (p < 0.05). The mean refractive astigmatism significantly decreased from ‒1.01 ± 1.3 to ‒0.79 ± 0.71, postoperatively (p = 0.029). In patients with marginal reflex distance < 2 mm, mean contrast sensitivity was increased (p < 0.001) and mean astigmatism was decreased significantly (p < 0.001) compared with those with ⩾ 2 mm. Higher order aberrations decreased significantly from 0.62 ± 0.41 µm to 0.55 ± 0.38 µm (p = 0.038) after blepharoplasty. Root mean square of the vertical trefoil (p = 0.038), vertical coma (p = 0.002), horizontal trefoil (p = 0.027), third-order aberration (p = 0.005), secondary vertical stigmatism (p = 0.001), spherical aberration (p = 0.023), secondary horizontal astigmatism (p = 0.002), fourth-order aberration (p = 0.024), vertical pentafoil (p = 0.015), secondary horizontal coma (p = 0.035), secondary horizontal trefoil (p = 0.030), and horizontal pentafoil (p = 0.048) were decreased significantly. Conclusion: Upper eyelid blepharoplasty in patients with dermatochalasis has a significant improvement in visual function in terms of contrast sensitivity, astigmatism, and higher order aberrations.

Changes in Visual Acuity and Refraction in the Exfoliation Syndrome. A Five-Year Follow-up Study

2001 ◽  
Vol 11 (3) ◽  
pp. 245-251 ◽  
Author(s):  
P.M. Puska ◽  
A.H.A. Tarkkanen
Keyword(s):  
Visual Acuity ◽  
Main Type ◽  
Exfoliation Syndrome ◽  
Follow Up Study ◽  
Exfoliative Glaucoma ◽  
The Difference ◽  
Term Management ◽  
Fellow Eyes

Purpose To examine changes in visual acuity (VA) and refraction in non-glaucomatous patients with unilateral exfoliation syndrome (EXS). Methods The best corrected values for VA (Snellen acuity cards) subjectively adjusted for refraction, and IOP were measured, and the development of lens opacities was examined in 46 non-glaucomatous patients with unilateral EXS. Results After five years the rate of conversion to bilateral exfoliation was 22% and to exfoliative glaucoma 30%. There was a significant decrease in VA in the exfoliative (E) eyes (median; QI, QIII, range: 1; 0.8, 1, 0.4-1.3 vs. 0.55; 0.4, 1, 0.05-1.4, p<0.0001) and the fellow, initially non-exfoliative (NE), eyes (1; 0.9, 1, 0.3–1.3 vs. 0.7; 0.5, 0.9, 0.1–1.4, p<0.0001) and a significant myopic change in refraction in the E eyes (+1.02 ± 2.48 vs. +0.11 ± 3.06, p=0.0001) and the NE eyes (+0.99 ± 2.25 vs. +0.43 ± 2.55 D, p<0.01). At study entry the difference in refraction between the fellow eyes (refraction in the NE eye – refraction in the E eye) was −0.27 ± 1.00D. After five years it was +0.32 ± 1.44 (p 0.016), reflecting greater myopic changes in the E eyes. The main type of lens opacification was nuclear sclerosis. Conclusions In five years, significant decreases in VA and myopic shifts in refraction occurred in the E and fellow eyes. The E eyes showed significantly greater myopic changes than the fellow eyes; the cause was clearly nuclear sclerosis, which must be taken into account in the long-term management of patients with EXS.

I. Note to a paper on the geometrical construction of the cell of the honey bee ('Roy. Soc. Proc.,' vol. 39, page 253)

1887 ◽  
Vol 41 (246-250) ◽  
pp. 442-443
Keyword(s):  
Honey Bee ◽  
Geometrical Construction ◽  
Simple Method ◽  
Straight Line ◽  
The Difference

The result obtained in the paper on the cell of the honey bee, read November 26, 1885, by which the side of one of the lozenges composing the cell was found to be three times the difference between the two parallel edges forming the sides of one of the trapeziums of the prism, gives a very simple method for constructing the figure as follows. On a straight line take a part AD, and lay off DC equal to twice AD, from D erect a perpendicular, and with radius AC = 3DA cut off DP; AC and AP are sides of the lozenge ACEP, which fulfils the required conditions. It is manifest that from this lozenge the remaining two lozenges and also the six trapeziums can he immediately constructed.

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