Schematic Eye Research Articles

Peter Orlebar Bishop. 14 June 1917—3 June 2012

Peter Orlebar Bishop was an Australian neurophysiologist renowned for his ingenious quantitative approach to the study of the mammalian visual system and his great ability to attract a large number of talented people to visual research. Peter’s research was based on specially designed, precise instrumentation and data quantification applied mainly to analysis of the response properties of single neurones in the principal dorsal thalamic visual relay nucleus, the dorsal lateral geniculate nucleus (LGNd) and the primary visual cortex. This quantitative bent was evident throughout Peter’s entire research career: starting with the design and construction of innovative DC amplifiers; to his quantitative analysis of optics, ‘schematic eye’ for the cat, which rivalled Gullstrand’s schematic eye for humans; to creating and demonstrating validity of the concept of ‘projection lines’ in the representation of contralateral visual field in different cellular layers of the LGNd of mammals with frontally positioned eyes and discovery of massive binocular input to single LGNd neurones. Peter’s engineering approach was probably at its heuristic peak when it revealed many details of binocular interactions at the level of single neurones in the primary visual cortex—the interactions which appear to underpin overall mechanisms underlying stereopsis, the high precision binocular depth sense.

Peter Orlebar Bishop 1917–2012

Peter Orlebar Bishop was an Australian neurophysiologist renowned for his ingenious quantitative approach to study of the mammalian visual system and great ability to attract a large number of talented people to visual research. Peter's research was based on specially designed, precise instrumentation and data quantification applied mainly to analysis of the response properties of single neurones in the principal dorsal thalamic visual relay nucleus, the dorsal lateral geniculate nucleus (LGNd) and the primary visual cortex. This quantitative bent was evident throughout Bishop's entire research career:starting with the design and construction of innovative DC amplifiers; through to his quantitative analysis of optics—‘schematic eye' for the cat, which rivaled Gullstrand's schematic eye for humans; to creating and demonstrating validity of the concept of ‘projection lines' in the representation of contralateral visual field in different cellular layers of the LGNd of mammals with frontally positioned eyes and discovery of a very substantial binocular input to single LGNd neurones. The engineering approach of Peter was probably at its heuristic peak when it revealed many details of binocular interactions at the level of single neurones in the primary visual cortex—the interactions that appear to underpin overall mechanisms underlying stereopsis, the high precision binocular depth sense.

Design of optical system for binocular fundus camera

A non-mydriasis optical system for binocular fundus camera has been designed in this paper. It can capture two images of the same fundus retinal region from different angles at the same time, and can be used to achieve three-dimensional reconstruction of fundus. It is composed of imaging system and illumination system. In imaging system, Gullstrand Le Grand eye model is used to simulate normal human eye, and Schematic eye model is used to test the influence of ametropia in human eye on imaging quality. Annular aperture and black dot board are added into illumination system, so that the illumination system can eliminate stray light produced by corneal-reflected light and omentoscopic lens. Simulation results show that MTF of each visual field at the cut-off frequency of 90lp/mm is greater than 0.2, system distortion value is −2.7%, field curvature is less than 0.1 mm, radius of Airy disc is 3.25um. This system has a strong ability of chromatic aberration correction and focusing, and can image clearly for human fundus in which the range of diopters is from −10 D to +6 D(1 D = 1 m−1).

Postnatal maturation of the fovea in Macaca mulatta using optical coherence tomography

Changes in the foveal anatomy during infancy are an important component in early development of spatial vision. The present longitudinal study in rhesus monkeys was undertaken to characterize the postnatal maturation of the fovea. Starting at four weeks after birth, the retinas of the left eyes of sixteen infant monkeys were imaged using spectral domain optical coherence tomography (SD OCT). Retinal scans were repeated every 30 days during the first year of life and every 60 days thereafter. Volume scans through the fovea were registered, scaled using a three surface schematic eye, and analyzed to measure foveal pit parameters. The individual layers of the retina were manually segmented and thicknesses were measured over a transverse distance of 1250 microns from the center of the foveal pit. Based on infrared scanning laser ophthalmoscope (IR SLO) images acquired with the SD OCT system, there were significant changes in the extent of the retina scanned as the eyes matured. Using a three-surface schematic eye, the length of each scan could be computed and was validated using image registration (R2 = 0.88, slope = 1.003, p < 0.05). Over the first 18 months of life, the mean retinal thickness at the pit center had increased by 21.4% with a corresponding 20.3% decrease in pit depth. The major changes occurred within the first 120 days, but did not stabilize until a year after birth. In Macaca mulatta infants, the primary anatomical maturation of the fovea occurs within the first few months of life, as determined by longitudinal data from SD OCT measurements. The timelines for maturation of the fovea correspond well with the normal development of the lateral geniculate nucleus, cortical neurophysiology, and spatial resolution in monkeys.

Determination of retinal surface area.

Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye invivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25±6.06years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50±4.03D and mean axial length (AL) 24.51±1.57mm. Mean TSA and RSA for the RE were 2058±189 and 1363±160mm2 , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P<0.01) which, contrasted with ST (365±43mm2 ), was significant for IT (340±40mm2 P<0.01), SN (337±40mm2 P<0.01) and IN (321±39mm2 P<0.01) quadrants. For all quadrants, QRSA was significantly correlated with AL (P<0.01) and exhibited equivalent increases in retinal area/mm increase in AL. Although the differences between QRSAs are relatively small, there was evidence of concordance with reported inter-quadrant patterns of susceptibility to retinal breaks associated with PVD. The data allow AL to be converted to QRSAs, which will assist further work on inter-quadrant structural variation.

Extended depth of focus contact lenses vs. two commercial multifocals: Part 1. Optical performance evaluation via computed through-focus retinal image quality metrics

PurposeTo compare the computed optical performance of prototype lenses designed using deliberate manipulation of higher-order spherical aberrations to extend depth-of-focus (EDOF) with two commercial multifocals. MethodsEmmetropic, presbyopic, schematic eyes were coupled with prototype EDOF and commercial multifocal lenses (Acuvue Oasys for presbyopia, AOP, Johnson & Johnson & Air Optix Aqua multifocal, AOMF, Alcon). For each test configuration, the through-focus retinal image quality (TFRIQ) values were computed over 21 vergences, ranging from −0.50 to 2.00D, in 0.125D steps. Analysis was performed considering eyes with three different inherent aberration profiles: five different pupils and five different lens decentration levels. ResultsExcept the LOW design, the AOP lenses offered ‘bifocal’ like TFRIQ performance. Lens performance was relatively independent to pupil and aberrations but not centration. Contrastingly, AOMF demonstrated distance centric performance, most dominant in LOW followed by MED and HIGH designs. AOMF lenses were the most sensitive to pupil, aberrations and centration. The prototypes demonstrated a ‘lift-off’ in the TFRIQ performance, particularly at intermediate and near, without trading performance at distance. When compared with AOP and AOMF, EDOF lenses demonstrated reduced sensitivity to pupil, aberrations and centration. ConclusionWith the through focus retinal image quality as the gauge of optical performance, we demonstrated that the prototype EDOF designs were less susceptible to variations in pupil, inherent ocular aberrations and decentration, compared to the commercial designs. To ascertain whether these incremental improvements translate to a clinically palpable outcome requires investigation through human trials.

Infants' object processing is guided specifically by social cues

Previous studies showed that the movements of another person's eyes and head guides infants' attention and promotes social learning by leading to enhanced encoding of cued objects. However, it is an open question whether social features like eyes are required or if the lateral movement of any arbitrary stimulus can elicit similar effects. The current experiments investigate the effects of the movement of a nonsocial cue and a perceptually similar social cue on object processing in 4-month-olds using event-related potentials (ERPs). Infants were presented with one of two central cues, either a box with a checkerboard pattern or a box with eye-like features on the front, which turned to one side. The cue thereby either turned toward a novel object or turned away from it. Afterwards, the object was presented again and ERPs in response to these previously cued or uncued objects were compared. When the nonsocial box served as the cue, no difference in neural processing of previously cued and uncued objects was found. In contrast, when the box with eyes served as the cue, we found an enhanced positive slow wave (PSW) for uncued as compared to cued objects. While the turning of the box with eyes promoted the encoding of cued objects, uncued objects needed enhanced activity for processing when presented for a second time. Results suggest that not every dynamic cue can influence infants’ object processing but that the presence of a basic social characteristic like isolated schematic eyes is sufficient to enhance social learning processes in early infancy. This hints on a specific sensitivity of the infant brain to social information which helps infants to focus on relevant information in the environment during social learning.

임상데이터에 근거한 여성 노안 모형안의 전산모사 연구

임상데이터에 근거한 여성 노안 모형안의 전산모사 연구

Accuracy of Axial Length Calculation Using Schematic Eyes in Ametropia

Accuracy of Axial Length Calculation Using Schematic Eyes in Ametropia

Q-optimized Algorithms: Theoretical Analysis of Factors Influencing Visual Quality After Myopic Corneal Refractive Surgery.

To model the effect of pupil size, optical zone, and initial myopic level on the retinal image quality after Q-optimized myopic corneal refractive surgery. Different Q-optimized and paraxial Munnerlyn algorithms were tested using a schematic myopic eye model to analyze the optical quality of the final retinal image for initial myopic errors from -1.00 to -7.00 diopters (D). Different optical zones (5.5, 6, and 6.5 mm in diameter) and two pupil diameters (5 and 7 mm, mesopic-scotopic conditions) were included in the comparison. Modulation transfer function (MTF) and area under the MTF from 0 to 60 cycles per degree (MTFa) were calculated by ray tracing to evaluate this retinal image quality. The Q-optimized algorithm with Q = -0.45 provided the highest MTF and MTFa results for myopic corrections less than -5.00 D. For refractive errors greater than -5.00 D, Q = -0.26 provided the highest MTF and MTFa results. Q-optimized algorithms improve the visual outcomes with respect to the paraxial Munnerlyn algorithm for myopic corneal surgery. The results show that the Q value that optimizes the results of the Q-optimized algorithm depends on the degree of myopia to correct and the size of the pupil. [J Refract Surg. 2016;32(9):612-617.].

Refractive shift of silicone oil tamponade in pseudophakic eye.

BackgroundRefraction change of silicone oil (SO) tamponade in phakic and aphakic eye has been studied thoroughly; however, it is rarely studied in pseudophakic eye. In this paper we aimed to deduce a theoretical formula predicting refractive shift of silicone oil tamponade in pseudophakic eye and compared it with clinical findings.MethodA theoretical formula was deduced through strict geometric optical principles under the Helmholtz Schematic eye model. Pre/postoperative refractive status of patients who previously underwent phacoemulsification, intraocular lens (IOL) implant, vitrectomy, SO tamponade and required SO extraction was studied.ResultsTwenty-six patients (27 eyes, 13 males and 13 females) were studied. Refractive error of SO-off was -1.88 ± 2.73D, and of SO-in was 2.02 ± 3.90. Refractive shift of SO tamponade was -3.90 ± 1.74D. Refractive shift was significantly associated with refractive power of IOL (r = -0.7903, p < 0.0001, Pearson correlation test) and anterior chamber distance (ACD, r = 0.3840, p = 0.0480, Pearson correlation test). Theoretical refractive shift was -4.10 ± 1.51D, and there was no significant difference between the theoretical and the clinical refractive shift (p = 0.3329, Paired T test).ConclusionsRefractive shift of SO tamponade in pseudophakic eye correlates with refractive power of implanted IOL and ACD, and strong correlation between theoretical formula and clinical findings was detected.Electronic supplementary materialThe online version of this article (doi:10.1186/s12886-016-0243-z) contains supplementary material, which is available to authorized users.

Predicting Accommodative Response Using Paraxial Schematic Eye Models.

Previous ultrasound biomicroscopy (UBM) studies showed that accommodative optical response (AOR) can be predicted from accommodative biometric changes in a young and a pre-presbyopic population from linear relationships between accommodative optical and biometric changes, with a standard deviation of less than 0.55D. Here, paraxial schematic eyes (SE) were constructed from measured accommodative ocular biometry parameters to see if predictions are improved. Measured ocular biometry (OCT, A-scan, and UBM) parameters from 24 young and 24 pre-presbyopic subjects were used to construct paraxial SEs for each individual subject (individual SEs) for three different lens equivalent refractive index methods. Refraction and AOR calculated from the individual SEs were compared with Grand Seiko (GS) autorefractor measured refraction and AOR. Refraction and AOR were also calculated from individual SEs constructed using the average population accommodative change in UBM measured parameters (average SEs). Schematic eye calculated and GS measured AOR were linearly related (young subjects: slope = 0.77, r = 0.86; pre-presbyopic subjects: slope = 0.64, r = 0.55). The mean difference in AOR (GS - individual SEs) for the young subjects was -0.27D and for the pre-presbyopic subjects was 0.33D. For individual SEs, the mean ± SD of the absolute differences in AOR between the GS and SEs was 0.50 ± 0.39D for the young subjects and 0.50 ± 0.37D for the pre-presbyopic subjects. For average SEs, the mean ± SD of the absolute differences in AOR between the GS and the SEs was 0.77 ± 0.88D for the young subjects and 0.51 ± 0.49D for the pre-presbyopic subjects. Individual paraxial SEs predict AOR, on average, with a standard deviation of 0.50D in young and pre-presbyopic subject populations. Although this prediction is only marginally better than from individual linear regressions, it does consider all the ocular biometric parameters.

Prediction of Axial Length Using Schematic Eyes in Emmetropia

Prediction of Axial Length Using Schematic Eyes in Emmetropia

Influence of Ametropia and Its Correction on Measurement of Accommodation

Amplitude of accommodation (AA) is reportedly greater for myopic eyes than for hyperopic eyes. We investigated potential explanations for this difference. Analytical analysis and computer ray tracing were performed on two schematic eye models of axial ametropia. Using paraxial and nonparaxial approaches, AA was specified for the naked and the corrected eye using the anterior corneal surface as the reference plane. Assuming that axial myopia is due entirely to an increase in vitreous chamber depth, AA increases with the amount of myopia for two reasons that have not always been taken into account. First is the choice of reference location for specifying refractive error and AA in diopters. When specified relative to the cornea, AA increases with the degree of myopia more than when specified relative to the eye's first Gaussian principal plane. The second factor is movement of the eye's second Gaussian principal plane toward the retina during accommodation, which has a larger dioptric effect in shorter eyes. Using the corneal plane (placed at the corneal vertex) as the reference plane for specifying accommodation, AA depends slightly on the axial length of the eye's vitreous chamber. This dependency can be reduced significantly by using a reference plane located 4 mm posterior to the corneal plane. A simple formula is provided to help clinicians and researchers obtain a value of AA that closely reflects power changes of the crystalline lens, independent of axial ametropia and its correction with lenses.

Relationship between retinal distance and object field angles for finite schematic eyes.

Retinal anatomical studies have used the Drasdo & Fowler three-refracting surface schematic eye to convert between retinal distances and object field angles. We compared its performance at this task with those of more sophisticated four-refracting surface schematic eyes. Raytracing was performed for Drasdo & Fowler, Lotmar, Navarro, Liou & Brennan, Kooijman and Atchison schematic eyes, and some of their variants. The Drasdo & Fowler eye gives a greater rate of change of object field angle with retinal distance at the retinal centre of about 5% than the other schematic eyes. This rate of change also increases much more quickly into the peripheral retina for the Drasdo & Fowler eye than for the other eyes. The reason for these differences is only that the Drasdo & Fowler eye is shorter than the other eyes. The relationship between retinal distance and visual field angle appears robust to changes in retinal radius of curvature when the retina is spherical. The retinal asphericity of Kooijman and Atchison eyes appears to play a role beyond 14 mm (~50°). Changing the length of the Drasdo & Fowler eye, to match those of the four-refracting surface schematic eyes, gives similar relationships between retinal distance and object field angle up to a retinal distance of approximately 14 mm (~50°). The relationship will change with refractive error as this is related to axial length and to retinal shape, and this should be taken into consideration for accurate conversions. For distances and angles beyond 14 mm and ~50°, retinal shape should be taken into account.

Qualitative analysis of the evaluation indicators and their related parameters of ametropic state

To investigate the theoretical basis and practical limitations of the existing calculation formulas in the evaluation of ametropic state. The evaluation indicators and their calculation parameters of ametropia were analyzed by using the reduced schematic model eye, the paraxial imaging principle, and the dimension laws. The existing formulas resulted from the reduced object vergence of object distance and image distance relation. Regarding the two measurement indicators of the existing formulas, diopter was misused for refractive power. "Ametropia degree" was a non-standard diction. Both of them were not suitable as the evaluation indicators. The outcomes of the existing formulas and their related plus or minus sign rules showed refractive corrections instead of refractive errors proper. For refractive errors, there was no suitable evaluation indicator. In the evaluation of ametropic state, there are fundamental problems in the existing formulas resulting from the reduced object vergence. The measurement indicators and their dimensional units are confused and misused. The calculation results refer to the refractive corrections only. The evaluation indicators for ametropia need to be further discussed.

Navarro 모형안을 이용한 노안 정밀모형안의 전산모사

목적: 본 연구는 Navarro 정밀모형안을 이용하고 임상데이터를 적용시킨 새로운 노안 모형안을 전산모사하는 것을 목표로 하였다. 방법: 40세, 50세, 60세 남성을 대상으로 선행연구로부터 광학적 매개변수에 관한 임상데이터를 수집하고, ZEMAX 광학프로그램을 이용하여 노안 정밀모형안을 설계하였다. 결과: 설계된 노안 정밀모형안들의 노안 진행 과정과 특징들이 선행연구들의 임상데이터들과 잘 일치하였다. 결론: Navarro 모형안을 기반으로 하여 임상자료와 상응하는 노안 정밀모형안을 새롭게 설계할 수 있었다. Purpose: This study was aimed to design new schematic eyes for presbyopia using the Navarro eye model and clinical data. Methods: We collected clinical data of eye-optical parameters of males in their age of 40, 50, and 60 from previous studies, and designed schematic eyes for presbyopia using the ZEMAX program. Results: The presbyopic process and features of the designed schematic eyes well accorded with the clinical data of previous studies. Conclusions: On the basis of the Navarro eye model, a finite schematic eyes for presbyopia were newly designed corresponding with clinical data.

Optical Analysis of the Gullstrand's Schematic Human Eye and a Myopic Astigmatism Human Eye by Using Matrix Method

Optical Analysis of the Gullstrand's Schematic Human Eye and a Myopic Astigmatism Human Eye by Using Matrix Method

Ultra-widefield retinal imaging through a black intraocular lens

To evaluate the feasibility of ultra-widefield retinal imaging in patients with near infrared (IR)-transmitting black intraocular lenses (IOLs). Oxford Eye Hospital, Oxford, United Kingdom. Laboratory evaluation of a diagnostic technology with interventional case report. The field of retinal imaging through a Morcher poly(methyl methacrylate) (PMMA) black IOL was determined in a purpose-built adult schematic model eye with the HRA2 Spectralis confocal scanning laser ophthalmoscope using standard imaging, Staurenghi retina lens-assisted imaging, and ultra-widefield noncontact imaging. Retinal imaging using each modality was then performed on a patient implanted with another Morcher PMMA black IOL model. Ultra-widefield noncontact imaging and lens-assisted imaging captured up to 150 degrees of field (versus 40 degrees with a standard confocal scanning laser ophthalmoscope). Ultra-widefield retinal images were successfully acquired in a patient eye with a black IOL. This study has identified the first ultra-widefield retinal imaging modalities for patients with near IR-transmitting black IOLs. Should larger studies confirm this finding, noncontact ultra-widefield confocal scanning laser ophthalmoscopy might be considered the gold standard imaging technique for retinal surveillance in patients with near IR-transmitting black IOLs. No author has a financial or proprietary interest in any material or method mentioned.

Optical performance of toric intraocular lenses in the presence of decentration.

To evaluate the optical performance of toric intraocular lenses (IOLs) after decentration and with different pupil diameters, but with the IOL astigmatic axis aligned. Optical performances of toric T5 and SN60AT spherical IOLs after decentration were tested on a theoretical pseudophakic model eye based on the Hwey-Lan Liou schematic eye using the Zemax ray-tracing program. Changes in optical performance were analyzed in model eyes with 3-mm, 4-mm, and 5-mm pupil diameters and decentered from 0.25 mm to 0.75 mm with an interval of 5° at the meridian direction from 0° to 90°. The ratio of the modulation transfer function (MTF) between a decentered and a centered IOL (MTFDecentration/MTFCentration) was calculated to analyze the decrease in optical performance. Optical performance of the toric IOL remained unchanged when IOLs were decentered in any meridian direction. The MTFs of the two IOLs decreased, whereas optical performance remained equivalent after decentration. The MTFDecentration/MTFCentration ratios of the IOLs at a decentration from 0.25 mm to 0.75 mm were comparable in the toric and SN60AT IOLs. After decentration, MTF decreased further, with the MTF of the toric IOL being slightly lower than that of the SN60AT IOL. Imaging qualities of the two IOLs decreased when the pupil diameter and the degree of decentration increased, but the decrease was similar in the toric and spherical IOLs. Toric IOLs were comparable to spherical IOLs in terms of tolerance to decentration at the correct axial position.