bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of clinical and eye movement characteristics between albinism and idiopathic infantile nystagmus with and without mutations in the FRMD7 gene
Authors: KUMAR AS , GOTTLOB I , PROUDLOCK FA , THOMAS S 
Published: September 2008

Abstract Purpose Nystagmus consists of involuntary to and fro oscillations of the eyes. The differences between nystagmus associated with albinism and idiopathic infantile nystagmus (IIN) are unclear. Recently mutations in a novel gene called FRMD7 have been found to underlie a significant proportion of X‐linked IIN. Phenotypic variations in eye movements between FRMD7 and non‐FRMD7 types have also been recently described. We have compared clinical and eye movement characteristics between albinism and IIN with and without mutations in the FMRD7 gene. Methods Clinical features and eye movement were recorded from 37 albino subjects, 83 subjects with the FRMD7 mutation and 45 subjects without the FRMD7 mutation. Results Mean visual acuity was significantly worse in albinos compared to IIN patients (p<<0.0001). Although there was no significant differences between the groups (p>0.05) for nystagmus amplitude or foveation, the frequency of nystagmus was significantly slower in albinism (p<<0.0001). In addition, nystagmus associated with albinism was significantly more likely to be jerk nystagmus rather than pendular nystagmus compared to FRMD7 group (p<<0.0001). The most common waveform associated with albinism was pure jerk nystagmus, whereas non‐FRMD7 was more likely to be associated with jerk with extended foveation. Conclusion Contrary to available literature, nystagmus associated with albinism shows distinct differences to IIN both with and without FRMD7 mutations. This suggests the possibility of different underlying mechanisms to albinism and IIN in generating eye oscillations although these are yet to be elucidated
Optical Coherence Tomography testing : possible biomarker value in multiple sclerosis?
Authors: RADOVIC N , PAVLOVIC D 
Published: September 2008

Abstract Purpose To assess retinal nerve fiber layer thickness ( RNFLT ), macula volume (MV) and visual acuity (VA) in multiple sclerosis (MS) eye , with or without optic neuritis (ON). Methods Optical coherence tomography ( OCT ) measures of the RNFLT and MV were studied in 14 patients with primary progressive multiple sclerosis ( 8 male / 6 female ‐ mean age 47 yrs ) and 12 patients with secondary progressive multiple sclerosis ( 5 male / 7 female ‐ mean age 41 yrs ). From the group with secondary progressive dissease 8 had history of ON. Control group consisted of 12 healthy control( 3 male / 9 female ‐ mean age 49 yrs ) underwent RNFLT and MV OCT testing. Results Of the patients eyes not affected by ON, mean RNFLT and macula volume were reduced when compared with control values.The mean RNFLT and MV were significantly decreased in secondary progressive MS group, but not in primary progressive MS, when compared with controls. Decreased RNFL and MV significantly correlated with decreased VA and visual field mean deviation. RNFL loss was most evident in the tmeporal quadrant, where significant reduction was seen in secondary compared to primary progression MS, and primary progression MS versus control group. Conclusion Progressive MS is manifesting more marked decrease in RNFLT and MV. OCT is promissing to detect subclinical changes in RNFL and MV, and could possibly considered as potential biomarker of reinal / brain involvement in MS.
The role for stimulus timing in local retinal responses: global propagation of retinal inhibition, in space and time
Authors: CASTELO‐BRANCO M , MAIA‐LOPES S , REIS AA , MATEUS C , SEBASTIAO AR , STASCHE M , FINGER J , NUNES S 
Published: September 2008

Abstract Purpose Stimulus timing strongly influences visual responsiveness, a dramatic example being the exquisite neural sensitivity to certain spatiotemporal patterns in photosensitive epilepsy. Local inhibition is a widely recognized property of mammalian retinal function. One signature of such adaptive inhibition is the reduced local response to a second flash. Here we studied global propagation of retinal inhibition, in space and time, as a function of temporal stimulus properties. Methods We have used a scanning laser ophthalmoscope based system interfaced with multifocal electroretinography to extract local retinal responses by means of standard reverse correlation techniques across 19 independent locations in 11 subjects. Results Specific manipulations of previous stimulus history and timing revealed invariable shifts of the balance between excitation and inhibition. Local responses were significantly inhibited, by the presentation of flashes within a preferred temporal window at other locations, depending of local flash modulation rate. Asymmetries were observed for P1, but not for the N1 component contribution, showing a retinal origin beyond the photoreceptor level. Conclusion These findings confirm that responses to even apparently homogeneous patterns may systematically shift depending on stimulus timing and that human retinal networks can globally adapt with exquisite temporal sensitivity, with local responses influencing far responses in space and time even when local stimulation patterns are independent.
What limits chromatic sensitivity in normal and colour deficient observers?
Authors: BARBUR JL , RODRIGUEZ‐CARMONA M , HARLOW JA 
Published: September 2008

Abstract Purpose Variability in chromatic sensitivity was assessed in normal trichromats (n=133) and in subjects with deutan (n= 106) and protan (n=48) deficiency. The purpose of this study was to quantify variability within normal colour vision and to determine how this impacts the assessment of minimum colour vision requirements within occupational environments. Methods Rayleigh matches were modelled with the aim of explaining the locations of match midpoints and ranges. Model parameters included the wavelength of peak sensitivity of cone photopigments, the photopigment optical density and the noise amplitude in the red/green colour channel. In order to avoid the suprathreshold, perceptual effects of extreme L:M cone ratios on colour vision, selective postreceptoral amplification of cone signals is needed. The noise is also amplified and this causes corresponding changes in red/green threshold sensitivity. Results We measured midpoint and matching range in anomaloscope matches and red/green and yellow/blue thresholds under conditions that isolate the use of colour signals. A subset of subjects with deutan deficiency that exhibited less common Nagel matches were selected for genetic analysis of their cone pigment genes to predict the corresponding peak wavelength separation of their two, long‐wavelength cone pigments. Conclusion The model predicts accurately the midpoint and the range for the spectral differences specified by the genes. The model also predicts the “normal” matches made by some subjects that rely on two hybrid genes and therefore exhibit red/green thresholds outside the normal range, typical of mild deuteranomaly. The anomaloscope is therefore not by itself sufficient to classify with certainty the colour deficiency involved.
New approach to establish safe colour vision limits for occupational environments
Authors: RODRIGUEZ‐CARMONA M , O'NEILL‐BIBA M , BARBUR JL 
Published: September 2008

Abstract Purpose Concern has been expressed that current colour vision (CV) standards in occupational environments tend to screen for normal trichromacy and may not therefore relate directly to actual CV requirements within specific working environments. Methods The new approach of establishing CV limits for specific occupations involves: ‐ measuring chromatic sensitivity and investigating the variability amongst normal trichromats ‐ accurate assessment of the severity of CV loss ‐ identifying the most important colour‐critical tasks at the work place when no redundancy is involved and discrimination of colour differences is most difficult ‐ simulating the most critical colour‐based tasks identified ‐ correlating the level of chromatic sensitivity and the subject’s performance of these tasks. Results A large number of normal trichromats and colour deficient observers have been examined on the CAD (Colour Assessment & Diagnosis) test. The test provides an accurate measure of the severity of CV loss (for red‐green and yellow‐blue discrimination) and diagnoses the class of deficiency involved. The findings from this study so far have produced minimum CV requirements in two specific occupational environments. These limits specify the level of chromatic sensitivity loss below which colour deficient subjects no longer perform the most demanding colour related tasks with the same accuracy as normal trichromats. Conclusion The new approach provides evidence‐based guidelines for minimum CV standards that can be implemented through objective testing without having to rely on either arbitrary limits or normal trichromacy. Further, this approach can be extended to other occupational environments where colour is important for carrying out visual tasks.
Variability of pupil behaviour due to different retinal’s illumination levels
Authors: SANCHEZ RAMOS C , DIAZ SERRANO Y , VINAS PENA M , RODRIGO E , BONNIN C , SILLERO QUINTANA M 
Published: September 2008

Abstract Purpose To get the knowledge about how can pupil size be manipulated, in an artificial way, by using optical filters, with different absorbances, in order to change the level of retinal’s illumination. This knowledge will allow the obtaining of an artificial myosis or mydriasis, with an optimal non‐invasive technology, so that will be applied in several ways. Methods The transversal study included data from 56 eyes of 28 subjects. To measure the different pupil size was used a digital binocular infrared pupillometer, which simulated 3 different light’s conditions: high mesopic (4lux), low mesopic (0,4lux) and scotopic (0,04lux). The obtained pupil size measurements, without filter, were compared with the results after the insertion of the different optical filters used: 16 filters with different transmittances (from 82% to 5%). Results Only in high mesopic (4lux) condition, the results showed significant differences between the pupil size measurements without and with different transmittance optical filters. The mean variation was between 10% and 14% depending on the filter which was used. Conclusion The existence of a physiologically visual system limit for myosis in scotopic condition was confirmed, due to the lower amount of light in retina. Only in high mesopic condition, significant differences were obtained in the pupil size results with filter.
Introduction to straylight as quality measure for ophthalmic procedures
Authors: VAN DEN BERG TJTP 
Published: September 2008

Abstract Purpose Often patients complain about halos, glare, hazy vision and blinding at night, but while doing regular tests like visual acuity, contrast sensitivity and slit lamp examination little unusual can be found. Most probably, the patient’s complaints are caused by increased large angle light scattering in the eye media which can not be detected by common tests, but straylight degrades the image projected on the retina, thus decreasing the quality of vision. Usually the variable for increasing ocular straylight is the crystalline lens and a cataract may cause a significant increase. Increased ocular straylight may also be caused by refractive surgery and pathological changes. Methods A forced choice psychophysical assessment technique was developed ("Compensation Comparison"), which resulted in a commercial product (C‐Quant from Oculus). The task of the patient is to make 25 short observations, comparing flicker strength in two half fields, and indicate with push buttons wich half field flickers most strongly. The straylight value is obtained including a reliability estimate. Added value in comparison to visual acuity was assessed in 2400 subjects in the European GLARE study. Results Straylight gives the part of the point‐spread‐function outside 1 degree. In contrast, visual acuity and contrast sensitivity relate to the psf within 0.3 degrees. Consequently, straylight assesses a part of the visual spectrum that is missed with the classical visual function measures. Patient studies have been performed on normal aging, cataract and cataract surgery, refractive surgery, YAG capsulotomy, etc. In all those studies straylight was often much increased, corresponding to complaints, while visual acuity was good. Conclusion Straylight is important to assess quality of vision.
Commercial interest
In‐vitro characterisation of corneal scatter in rabbit corneas following PRK
Authors: GINIS H , DE BROUWERE D , PENTARI I , PALLIKARIS I 
Published: September 2008

Abstract Purpose The present work pertains to the measurement of light scatter in rabbit corneas after Excimer laser treatment, to the microscopic characterisation of the corneal irregularities and to the development of a mathematical model of light propagation through the post‐laser treatment cornea, based on the statistical properties of the scattering structures. Methods Fourteen rabbits underwent photorefractive keratectomy (‐6D). Nine to twelve weeks postoperatively, after confocal imaging, animals were sacrificed and the corneas were excised. The intensity and angular distribution of scatter was measured by enclosing the excised rabbit corneas between two glass elements to form a triplet lens. This lens was used with a CCD camera to record images projected on a computer screen. Scatter intensity and distribution was calculated by measuring the intensity in small dark disk concentric with a series of bright disks. After the scatter measurement, the corneas were examined histologically. The structures observed using the confocal microscope ‐corresponding to refractive index (and therefore optical path difference) variation were fitted with a fractal surface band‐pass filtered in the Fourier domain. Results Scattered light is characterised by a narrow forward distribution. Scatter is dominated by the subepithelial structures having sizes of the order of 50‐150 microns. The modelling of scatter by means of a spatially filtered fractal surface corresponding to OPD results to predictions in accordance to the experimental data. Conclusion Forward scatter following PRK can be attributed mainly to the subepithelial irregular layer. The angular distribution of scatter is in accordance to the size of structures observed microscopically in this layer.
Glare test as indicator for cataract surgery
Authors: TASSIGNON MJ , ROZEMA JJ 
Published: September 2008

Abstract Purpose The concept of glare, as determined by the Oculus C‐Quant device, can be useful in clinical practice as additional parameter to guide the surgeon in its decision for cataract surgery. Before to decide upon pathological conditions of glare, benchmarks of what is considered normal should be available. Methods The C‐Quant device was calibrated in the Department of Ophthalmology of the Antwerp University Hospital in order to achieve benchmarks of what is “physiological” glare. Results Based on the results of the Gullstrand Benchmark study, glare in our “normal” population was found slightly higher than in other settings. Glare was also measured prior to each cataract operation as well as after cataract surgery. Conclusion Two conclusions can be drawn: it might be important to calibrate each individual machine before testing pathology, and glare is generally increased prior to cataract surgery and decreased after successful cataract surgery.
Risk factors for progression in glaucoma. The Groningen Longitudinal Glaucoma Study
Authors: JANSONIUS NM , WESSELINK C , HEEG GP 
Published: September 2008

Abstract Purpose To investigate risk factors associated with visual field progression in glaucoma. Methods 221 patients with a reproducible glaucomatous visual field defect at baseline were followed prospectively with perimetry (HFA 30‐2). Three criteria for progression were used: the EMGT algorithm (GPA), a non‐parametric algorithm applied to mean deviation (MD; NPA) and MD slope. For progression according to GPA, the last field had to be labelled as possible or likely progression. For progression according to NPA, the last two or more consecutive fields had to have an MD value worse than the worse baseline MD value. Risk factor analyses were performed using Cox proportional hazard models (dependent variables: classification by GPA and NPA) and multiple linear regression (dependent variable: MD slope). Results Mean follow‐up was 5.4 years; on average 7.2 reliable fields were available. Mean MD at baseline and MD slope during follow‐up were ‐9.9 dB and ‐0.26 dB/yr for OD and ‐9.0 dB and ‐0.21 dB/yr for OS. Of 167 eligible right eyes, 45 showed progression with GPA and 69 with NPA. For OS, these numbers were 36 and 67 of 167. Mean IOP during follow‐up (per mmHg increase; GPA: HR 1.13, P=0.014; NPA: HR 1.10, P=0.016; MD slope: ‐0.042 dB/yr/mmHg, P=0.002) and disease stage (early versus moderate/severe glaucoma with MD = ‐6 dB as cut‐off point; GPA: HR 1.88, P=0.034; NPA: HR 2.05, P=0,001; MD slope: ‐0.20 dB/yr, P=0.010) were found to be significant risk factors. Less convincing associations were found for family history of glaucoma and age. Highest IOP ever measured, myopia, sex and cardiovascular disease were not associated with progression. Conclusion Higher mean IOP during follow‐up and worse disease stage at baseline were associated with progression.
Higher‐order wavefront aberrations and accommodative response variations with phenylephrine 5%
Authors: GICQUEL JJ , NGUYEN–KHOA JL , HARMS F , LOPEZ GIL N , LEGRAS R , DIGHIERO PL , LEBUISSON DA , LE GARGASSON JF 
Published: September 2008

Abstract Purpose To study the effects of phenylephrine 5% topical administration on accommodative response and optical aberrations variation. Methods The research followed the tenets of the Declaration of Helsinki . 28 eyes from 14 volunteers with spherical equivalent defocus error between –2D and +1D, no eye disease history and between 20 to 25 years of age, underwent wavefront measurements with a Shack–Hartmann wavefront aberrometer which included a movable accommodative target. Wavefront data was acquired while applying 6 different increasing accommodative stimuli, from 0 D to 5 D by steps of 1 D, before and after pupil dilation with Phenylephrine 5%. Results The dilation using Phenylephrine 5% was found to larger lag errors in the accommodative response of about half of the subjects. The total RMS amount of aberrations above defocus remained stable during accommodation with and without dilation. Spherical aberration was positive in average in the non accommodated eye and changed toward negative values with increasing accommodation (p<0.05). Cylinder axis came closer to 90° as accommodation increased (p<0.05). Although vertical coma did not significantly vary with accommodation, horizontal coma increased significantly with accommodation (p<0.05). These changes in aberrations with increasing accommodation were similar on average in both pupil conditions. Conclusion Phenylephrine 5% modifies the accommodative focus response of a significant proportion of young adult eyes. Wavefront aberrations above defocus undergo similar variations in both natural and dilated pupil conditions. However the total RMS error of aberrations above defocus remains relatively constant when the eye accommodates.
Accommodative function in school ‐age children with poor reading skills
Authors: PALOMO‐ALVAREZ C , PUELL MC 
Published: September 2008

Abstract Purpose Prior findings suggest correlation between reading problems and accommodative function, but few studies have assessed accommodation in children with poor reading skills. Our aim was to characterize monocular accommodative amplitude, relative accommodation and binocular accommodative facility in a population of healthy, non‐dyslexic primary school children with reading difficulties. Methods We conducted a cross‐sectional study on 87 poor readers and 32 control children (all 8‐13 years of age) in grades three to six recruited from eleven elementary schools in Madrid, Spain. In each subject with best spectacle correction, negative relative accommodation and positive relative accommodation were measured using a phoropter, monocular accommodative amplitude was determined using the minus lenses method, and binocular accommodative facility was measured using the Bernell Acuity Suppression Slide (VO/9) and a ± 2.00 D accommodative demand during 1 minute. Results Monocular accommodative amplitude was significantly lower (p < 0.001) in the group of poor readers (right eye 9.1 D ± 2.3, left eye 9.0 D ± 2.3) than in the control group (right eye 10.5 D ± 1.7, left eye 10.5 D ± 1.7). Binocular accommodative facility values were significantly lower (p<0.05) in the poor readers (4.9 cpm ± 3.1) than controls (6.3 cpm ± 2.9). Negative and positive relative accommodation values were similar in both groups of children. Conclusion This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility such that this function should be assessed by an optometric clinician in children whose reading level is below average.
Effect of litter size and birth weight on naturally occurring myopia in the Labrador retriever
Authors: PHILLIPS JR , BLACK J , BROWNING SR , COLLINS AV 
Published: September 2008

Abstract Purpose To evaluate early environmental influences (e.g. litter size, birth weight, birth season) on adult refractive error in dogs. A previous familial aggregation analysis has shown that the distribution of refractive error in a large family of pedigree Labrador Retrievers has a significant genetic component, but that litter size and other residual/environmental factors also have significant effects. Methods Refractive error was measured by cycloplegic retinoscopy in both eyes of 166 dogs, 1‐8 years of age and free of ocular pathology, from a large family of pedigree Labrador Retrievers. All dogs originated from the same breeding colony. The early records of these dogs included information on birth weight, maternal litter cohort, litter size and neonatal weight gain, measured daily for the first 6 weeks. These factors were analyzed to investigate their effect on adult refractive error. Results The average adult spherical equivalent refraction (SER) was ‐0.44D (‐5.38D to +1.65D, n = 166): 35% were myopic (SER ≤ ‐0.50D), 58% emmetropic (SER = ‐0.49 to +0.99) and 7% hyperopic (SER ≥ +1.00D). Mean birth weight was 421±57g. Higher birth weight was weakly (R=0.3) correlated with more hyperopic adult refractions. Relative to large litters (≥ 7), dogs from small litters (< 7) gained more weight within the first 6 weeks of life and were on average 0.43D more myopic. Conclusion The dog provides a unique model for studying a wide range of environmental influences on the development of naturally occurring, high prevalence, low degree myopia.