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Contrast discrimination determines the threshold contrast required to distinguish between two suprathreshold visual stimuli. It is typically measured using sine-wave gratings. We first present a modification to Barten’s semi-mechanistic contrast discrimination model to account for spatial frequency effects and demonstrate how the model can successfully predict visual thresholds obtained from published classical contrast discrimination studies. Contrast discrimination functions are then measured from images of natural scenes, using a psychophysical paradigm based on that employed in our previous study of contrast detection sensitivity. The proposed discrimination model modification is shown to successfully predict discrimination thresholds for structurally very different types of natural image stimuli. A comparison of results shows that, for normal contrast levels in natural scene viewing, contextual contrast detection and discrimination are approximately the same and almost independent of spatial frequency within the range of 1–20 c/deg. At higher frequencies, both sensitivities decrease in magnitude due to optical limitations of the eye. The results are discussed in relation to current image quality models.

Background: Vision is an adaptive function and should be considered a prerequisite for neurodevelopment because it permits the organization and the comprehension of the sensory data collected by the visual system during daily life. For this reason, the influence of visual functions on neuromotor, cognitive, and emotional development has been investigated by several studies that have highlighted how visual functions can drive the organization and maturation of human behavior. Recent studies on animals and human models have indicated that visual functions mature gradually during post-natal life, and its development is closely linked to environment and experience. Discussion: The role of vision in early brain development and some of the neuroplasticity mechanisms that have been described in the presence of cerebral damage during childhood are analyzed in this review, according to a neurorehabilitation prospective.

Aberrant production of reactive oxygen species (ROS) is a common feature of damaged retinal neurons in diabetic retinopathy, and antioxidants may exert both preventive and therapeutic action. To evaluate the beneficial and antioxidant properties of food supplementation with Lisosan G, a powder of bran and germ of grain (Triticum aestivum) obtained by fermentation with selected lactobacillus and natural yeast strains, we used an in vivo model of hyperglycemia-induced retinal damage, the fruit fly Drosophila melanogaster fed with high-sucrose diet. Lisosan G positively affected the visual system of hyperglycemic flies at structural/functional level, decreased apoptosis, and reactivated protective autophagy at the retina internal network. Also, in high sucrose-fed Drosophila, Lisosan G reduced the levels of brain ROS and retina peroxynitrite. The analysis of oxidative stress-related metabolites suggested 7,8-dihydrofolate, uric acid, dihydroorotate, γ-L-glutamyl-L-cysteine, allantoin, cysteinyl-glycine, and quinolate as key mediators of Lisosan G-induced inhibition of neuronal ROS, along with the upregulation of glutathione system. Of note, Lisosan G may impact oxidative stress and the ensuing retinal cell death, also independently from autophagy, although the autophagy-ROS cross-talk is critical. This study demonstrated that the continuous supplementation with the alimentary integrator Lisosan G exerts a robust and multifaceted antioxidant effect on retinal neurons, thus providing efficacious neuroprotection of hyperglycemic eye.

The objective of this study was to compare visual parameters and retinal layers’ morphology pre-treatment (baseline) and 6 months post-treatment in polypoidal choroidal vasculopathy (PCV) eyes. A single centre, longitudinal, prospective study was conducted at a public tertiary hospital of Malaysia. Visual parameters including distance and near visual acuity (DVA and NVA), contrast sensitivity (CS), reading speed (RS), and different qualitative and quantitative optical coherence tomography (OCT) parameters were evaluated pre- and 6 months post-treatment. Thirty-three naïve PCV eyes of 32 patients (mean age of 67.62 years) were evaluated pre- and post-treatment of intravitreal ranibizumab with and without photodynamic therapy. After treatment, sub retinal fluid decreased from 27 eyes (84.35%) at baseline to 7 eyes (21.88%) at 6 months while pigment epithelium detachment decreased from 32 eyes (100%) at base line to 15 eyes (46.87%) at 6 months. Mean pre-treatment quantitative morphological OCT retinal parameters including thickness and volume of central sub field, center thickness, center minimum, and maximum thickness reduced significantly. Similarly, all visual parameters including DVA, NVA, CS, and RS showed statistically significant improvement. While 89% of the eyes showed improvement in CS, 78%, 71%, and 65% of the eyes showed improvement in NVA, RS, and DVA, respectively. Thus, CS was the most treatment responsive visual parameter.

The article focuses on the structure and the dynamics of partial functions of visual skills (visual segmentation – visual differentiation of the figure/background, visual differentiation of shapes and visual memory) children during their last year at nursery school and their first two years of school attendance as a part of the research project of the Faculty of Education, Palacký University Olomouc. The stimulus material of the investigation was made up of diagnostic and reeducation instruments by Viennese professor B. Sindelar. The Sindelar’s instrument has no norms, the aim of the investigation was to determine the median values of the performances in the aforementioned areas of visual perception of children and thus to determine the dynamics of the development of these functions in the intact population. The research sample consisted of children from pupils of Moravian and Prague schools – the last year of kindergarten and the first two years of elementary school, it was a deliberate and institutional sample selection. Since the survey had a quantitative design, a statistical procedure was used to analyze the collected data (median value, statistically significant difference between respondent groups was determined by the Mann–Whitney test). The results of the investigation were demonstrated by a table and a graph for each subtest.

In early and intermediate age related macular degeneration (ARMD), visual acuity alone has failed to explain the complete variation of vision. The aim of the present study was to determine correlation between different visual functions and retinal morphology in eyes with early and intermediate ARMD. In this single center cross sectional study, patients diagnosed as early or intermediate ARMD in at least one eye were recruited. Visual functions measured were best- corrected distance visual acuity (DVA), near vision acuity (NVA), reading speed (RS), and contrast sensitivity (CS). Parameters such as thickness (RT) and volume (RV) of the retina, outer retinal layer thickness (ORLT) and volume (ORLV), outer nuclear layer thickness (ONLT) and volume (ONLV), retinal pigment epithelium layer-Bruch&rsquo, s membrane complex thickness (RPET) and volume (RPEV) were assessed employing semi-auto segmentation method of Spectralis optical coherence tomography (OCT). Twenty-six eyes were evaluated. DVA, CS, and RS showed significantly good correlation with RPET, ONLT, and ONLV, whereas NVA showed good correlation with ONLV and RPET. The present study concluded that RS, CS, NVA, and DVA represent the morphological alteration in early stages and should be tested in clinical settings. ONLT, ONLV, and RPET morphological parameters can be employed as important biomarkers in diagnosis of early to intermediate ARMD.

Purpose This study was undertaken to find correlations between visual functions and visual disabilities in patients with diabetic retinopathy. Method A cross-sectional study was carried out among 38 visually impaired diabetic retinopathy subjects at the Low Vision Clinic of B.P. Koirala Lions Centre for Ophthalmic Studies, Kathmandu. The subjects underwent assessment of distance and near visual acuity, objective and subjective refraction, contrast sensitivity, color vision, and central and peripheral visual fields. The visual disabilities of each subject in their daily lives were evaluated using a standard questionnaire. Multiple regression analysis between visual functions and visual disabilities index was assessed. Result The majority of subjects (42.1%) were of the age group 60–70 years. Best corrected visual acuity was found to be 0.73 ± 0.2 in the better eye and 0.93 ± 0.27 in the worse eye, which was significantly different at p = 0.002. Visual disability scores were significantly higher for legibility of letters (1.2 ± 0.3) and sentences (1.4 ± 0.4), and least for clothing (0.7 ± 0.3). Visual disability index for legibility of letters and sentences was significantly correlated with near visual acuity and peripheral visual field. Contrast sensitivity was also significantly correlated with the visual disability index, and total scores. Conclusion Impairment of near visual acuity, contrast sensitivity, and peripheral visual field correlated significantly with different types of visual disability. Hence, these clinical tests should be an integral part of the visual assessment of diabetic eyes.

AIM:To compare posterior capsule opacification (PCO) degree and visual functions after phacoemulsification in eyes implanted with 360-degree square edge hydrophilic acrylic intraocular lens (IOL) (570C C-flex, Rayner) and sharp edge hydrophobic acrylic IOL (Sensar AR40e, AMO) in diabetic patients.METHODS:Sixty diabetic patients underwent uneventful phacoemulsification and randomly implanted one of the two IOLs. The PCO value was measured by retroillumination photographs and Evaluation of Posterior Capsule Opacification (EPCO) 2000 image-analysis software at 1, 6, 12, and 24mo after surgery. Visual acuity, and contrast sensitivity in photopic and mesopic conditions were also examined at each follow up time point. The incidence of eye that required Nd:YAG laser posterior capsulotomy were also compared.RESULTS:There was not any statistically significant difference in PCO scores between Rayner C-flex 570C group and Sensar AR40e group at each follow up time point. Visual acuity, Nd:YAG capsulotomy incidence and contrast sensitivity also had no significant difference during the 24mo follow-up.CONCLUSION: For diabetic patients, Rayner 570C C-flex and Sensar AR40e IOLs are same effective for prevent PCO. The 360-degree square edge design maybe is a good alternative technique to improve PCO prevention.

Objectives To assess the stability of axis and patient satisfaction after toric visian implantable collamer lens (TICL) implantation for moderate to high myopic astigmatism. Methods Total 33 eyes of 21 consecutive patients who underwent implantation of TICL for the correction of moderate to high myopic astigmatism were recorded and a minimum follow-up of six months was performed. The deviation of axis of TICL was detected from one week to six months postoperatively. The evaluation of the visual functions was done by the same clinician at six months after surgery. Results The mean refractive cylinder decreased from -2.48±0.91 diopters (D) preoperatively to -0.54±0.25D and -0.50±0.19D at one week and six months after surgery respectively. Mean changes in astigmatism from one week to six months after surgery was 0.03±0.17D. The mean deviation of axis of TICL from one week to six months postoperatively was 2.48±1.25°(range,1°~ 6°) and no TICL required secondary repositioning. 14.3% patients felt difficult about the middle distant visual function (Reading Computer Screen). Evaluations of other visual functions were positive or very positive. Conclusions : Six months after implantation of the TICL, it showed slightly axis rotation and high satisfaction about the visual functions.

BACKGROUND: Children with perinatal brain damage have a high prevalence of visual impairment. Stimulation of vision at a critical period can encourage brain plasticity and the recovery of impaired function. OBJECTIVE: The aim of our study was to investigate when is the critical period for visual stimulation in children with perinatal brain damage. METHODS: We compared 35 children within the first eight months of life (median age = 4 months) to 35 children aged between eight and thirty months (median age = 15 months), all with perinatal brain damage. All the children were attending an early intervention program at Mali dom, Zagreb, a rehabilitation centre for children with visual impairment. We compared the results from baseline and follow-up assessments of visual functions (grating acuity and contrast sensitivity). We also compared differences in change scores between the two groups. RESULTS: Our results have shown that children who commence a visual stimulation program within the first eight months of life had more improvement in both visual functions. This improvement is statistically significant in visual acuity (p = 0.048). CONCLUSIONS: These results indicate the importance of starting a visual stimulation program within the first eight months after birth.

Background : We assessed visual functioning of the children with special needs in Oman between 2009 and 2012. We present the methods of assessing different visual functions, outcomes and interventions carried out to improve their functioning. Materials and Methods : In this case series type of study, optometrists assessed visual functions of children of "day care centers" in Oman. Experts further assessed them and provided low vision care. Ocular movements, refractive corrections, near, distance, contrast color, motion, field of vision and cognitive, visual function test results were noted. Feedback to caregivers was given to improving visual functioning of these children. Results: We grouped 321 participants, (196 (61.1%) boys, age range of 3-18 years) into 61; Down syndrome (DS), 72 with intellectual disabilities, 67; hearing impaired and 121 with other conditions. Refractive error and lag of accommodation was 26 (42.6%) and 14 (22.6%) among children with DS. Contrast sensitivity was impaired in 8 (12.7%) among hearing impaired children. Defective distant and near vision was in 162 (70%) and 104 (42%) of our cohort. Children with intellectual disability were most difficult to assess. Children in group of other disabilities′′ had a higher proportion of impaired visual functioning. They were given low vision aids (telescopes (22), filters (7) and magnifiers (3)) in large numbers compared to those in other groups. Conclusions : The outcomes of assessment of visual functioning of children with other disabilities show great variation and difficult to group. The care therefore should be individual. All visual functions cannot be assessed at one time.

Background and Objective. The aim of this study was to evaluate associations between visual functions (visual acuity, perimetry, optic nerve disc condition, and color contrast sensitivity) and pituitary adenoma (PA) diameter. Material and Methods. In the study, 20 patients with PA, which was confirmed by computed tomography or magnetic resonance imaging scans, were examined. The patients were divided into 2 groups: those with a PA diameter of ≤1 cm (14 eyes) and with a PA diameter of >1 cm (26 eyes). The control group comprised 40 healthy age- and gender-matched persons (80 eyes). The diameter of PA, visual acuity, and perimetry were analyzed; the F-M 100 hue test for color discrimination was used in patients with PA. Results. Visual acuity was better in the control group as compared with both groups of patients (1.0 vs. 0.90 [SD, 0.50] and 0.64 [SD, 0.21]; P=0.01; respectively). The results of the Farnsworth- Munsell 100 hue test were also better in the control group compared with the patients with PA of ≤1 cm and >1 cm (error score of 80.1 [SD, 53.0] vs. 131.8 [SD, 30.6] and 244.68 [SD, 51. 6], respectively; P=0.011). There was a very strong positive correlation between the error score of the F-M 100 hue test and PA diameter (r=0.905), but the correlation between the error score and visual acuity (r=–0.32), perimetry (r=0.21), and eye fundus changes (r=0.36) and PA diameter was weak. Conclusions. Our results showed that PA can cause the impairments of visual acuity, perimetry, and color contrast sensitivity. The computerized F-M 100 hue test can be one of the methods for an early diagnosis of chiasm damage in patients with PA.

We investigated a case of unilateral optic nerve hypoplasia using spectral domain optical coherence tomography (SDOCT). Optical coherence tomography was done on both eyes using 5-line Raster scan for the fovea to analyze the retinal nerve fiber layer thickness, inner retinal layer thickness, outer retinal layer thickness, and optic disc cube scan for the disc. Retinal nerve fiber layer thickness, inner retinal layer thickness, and outer retinal layer thickness were manually measured at 21-points of each five lines, and results were compared between both eyes. Retinal nerve fiber layer thickness and inner retinal layer thickness of optic nerve hypoplasia were significantly thinner than the opposite eye, but there was no significant difference in the thickness of the outer retinal layer between both eyes.

Aim: To investigate the longitudinal change in central corneal thickness (CCT) over 3 years in patients with glaucoma. Materials and Methods: The Chennai Glaucoma Follow-up Study, an offshoot of the Chennai Glaucoma Study, was designed to evaluate the progression of glaucoma. A cohort of participants in the Chennai Glaucoma Study that were suffering from glaucoma or were at a higher risk for glaucoma underwent comprehensive ophthalmic evaluation at the base hospital at 6-month intervals during the years 2004 to 2007. The CCT (average of 10 readings) was measured between 11 am and 1 pm on any given day using an ultrasonic pachymeter. Patients with a history of ocular surgery, corneal disease and usage of topical carbonic anhydrase inhibitor were excluded. No patient was a contact lens wearer. Results: One hundred and ninety-six patients (84 male, 112 female) met the inclusion criteria. We analyzed data from the right eye. The mean age of the patients was 59.97 ± 9.06 years. Fifty-nine (30.1%) of the patients were diabetic. The mean change in CCT (CCT at first patient visit - CCT at last patient visit) was 3.46 ± 7.63 μm. The mean change in CCT was 0.75 μm per year (R 2 = 0.00). Age, gender, intraocular pressure at the first patient visit and diabetic status had no significant influence on the magnitude of change in CCT. Conclusion: A carefully obtained CCT reading by a trained examiner need not be repeated for at least 3 years as long as the ocular and systemic factors known to affect the measurement of CCT are constant.

Rhinosporidium seeberi , till recently known as a fungus, has been reclassified as a protistan parasite. It infects humans and many animal species. The authors describe a rare case of oculosporidiosis with involvement of the lacrimal sac exhibiting features of idiopathic orbital inflammatory disease in a young male patient. Clinical features, pathophysiology, and management of lacrimal sac rhinosporidiosis have been discussed.

WOS: 000330854300008, PubMed: 24145558, Aims: The aim of this study was to compare the visual field test results in healthy children obtained via the Humphrey matrix 24-2 threshold program and standard automated perimetry (SAP) using the Swedish interactive threshold algorithm (SITA) -Standard 24-2 test. Materials and Methods: This prospective study included 55 healthy children without ocular or systemic disorders who underwent both SAP and frequency doubling technology (FDT) perimetry visual field testing. Visual field test reliability indices, test duration, global indices (mean deviation [MD], and pattern standard deviation [PSD]) were compared between the 2 tests using the Wilcoxon signed-rank test and paired t-test. The performance of the Humphrey field analyzer (HFA) 24-2 SITA-standard and frequency-doubling technology Matrix 24-2 tests between genders were compared with Mann-Whitney U-test. Results: Fifty-five healthy children with a mean age of 12.2 +/- 1.9 years (range from 8 years to 16 years) were included in this prospective study. The test durations of SAP and FDT were similar (5.2 +/- 0.5 and 5.1 +/- 0.2 min, respectively, P = 0.651). MD and the PSD values obtained via FDT Matrix were significantly higher than those obtained via SAP (P < 0.001), and fixation losses and false negative errors were significantly less with SAP (P < 0.05). A weak positive correlation between the two tests in terms of MD (r = 0.352, P = 0.008) and PSD (r = 0.329, P = 0.014) was observed. Conclusion: Children were able to complete both the visual test algorithms successfully within 6 min. However, SAP testing appears to be associated with less depression of the visual field indices of healthy children. FDT Matrix and SAP should not be used interchangeably in the follow-up of children.

Background: We evaluated the refractive status and visual function of children with special needs (other handicap) in 2010 and compared them with healthy 1 st grade school students in Oman. Materials and Methods: This was a cohort study. Optometrists recorded vision using a logarithm of minimum angle of resolution (LogMAR) chart. Preferential looking method was used for testing 31 children. Cycloplegic refraction was performed on all children. Contrast sensitivity was tested using 2.5%, 10%, and 100% contrast charts. Ocular movement, alignment, and anterior segment were also assessed. A pediatrician reviewed the health records of all the children at the time of their enrollment in this study to determine if the child had been diagnosed with a systemic condition or syndromes. The visual functions were assessed by study investigators. We estimated the rates and the risk of different visual function defects in children with special needs. Result: The prevalence of refractive error in 70 children (4.7 ± 0.8 years) with special needs (group 1) and 175 normal healthy first grade students (group 2) were 58.5% and 2.9%, respectively. The risk of refractive error was significantly higher in children with special needs [relative risk, 48.1 (95% confidence interval, 17.54-131.8)]. Hyperopia (>1.00 D), myopia (≥ 1.00D) and astigmatism (≥ ±1.00 D) were found in 18.6%, 24.3%, and 27.1%, respectively, in group 1. Six children in this group had defective near vision. Sixteen (80%) children with Down syndrome had refractive error. Seven (50%) children with developmental disorder showed decreased contrast sensitivity. Conclusion: Prevalence of uncorrected refractive error was much higher in children with special needs. Prevalence of strabismus, nystagmus, and reduced contrast sensitivity was also higher in children with special needs. Early vision screening, visual function assessment, correction of refractive error, and frequent follow-up are recommended.

Objective : To determine the effects of the visual functions on the occurrence of road traffic accidents (RTA) amongst commercial drivers in Ife central local government area (LGA) of Osun state of Nigeria. Design : A cross-sectional study. Settings : Four major motor parks located at Ife Central LGA. Materials and Methods : Of the estimated 270 commercial drivers in the four major parks of the LGA, 215 consecutive drivers were interviewed and had their eyes examined. Structured questionnaires were administered by an ophthalmologist. Results: The prevalence of visual impairment (visual acuity < 6/18) in the better eye without correction was 3.3% ± 2.4 and there was a significant association between uncorrected visual acuity impairment in the better eye and RTA ( P = 0.0152). Refractive error was seen in 8.4% of the drivers, but none of these wear corrective glasses. Visual field defect, abnormal stereopsis and color vision impairment did not have any significant association with RTA. Conclusion : Poor visual acuity is strongly associated with RTA amongst Nigerian commercial drivers as opposed to visual field defect, abnormal color vision and stereopsis. A significant proportion of visual impairment was due to uncorrected refractive errors.

Purpose The aim was to assess visual functions in patients with retinoblastoma (Rb) after treatment and complete cure and the effect of this on quality of life by means of visual functioning questionnaire-39 (VFQ-39). Patients and methods A cross-sectional study was carried out in the period from July 2017 to February 2018 in Ophthalmology Department, Ain Shams University Hospital, Retinoblastoma Clinic. A total of 30 patients were recruited at least after 1 year of complete cure from Rb. They were classified into two groups: group I included unilateral cases (15 patients), and group II included bilateral cases (15 patients). All children were subjected to detailed history, and ophthalmological examination included best-corrected visual acuity (BCVA), binocular and color vision assessment, and dilated fundus examination. Scoring of VFQ-25 and VFQ-39 subscales was conducted by the parents. Results Mean overall vision-related quality of life scores were 90.5±10.45 (range: 60.9–100) and 89.1±8.59 (range: 76.1–100) in groups I and II, respectively, with no difference of statistical significance being found between them (P=0.86), with marked affection of mental health in group II. A highly statistically significant negative correlation was found between each of BCVA (logMAR) and duration of therapy and the mean total score (r: −0.57, P=0.001, and (r: −0.41, P=0.04, respectively). Conclusion High scores regarding VFQ-25 and VFQ-39 subscales were achieved in older children with Rb, with no difference between unilateral and bilateral cases. BCVA and duration of therapy had a big influence on the results.