Basis Of Visual Acuity Research Articles

Effectiveness of SMILE Combined with Micro-Monovision in Presbyopic Patients: A Pilot Study

Binocular summation along all defocus range after a micro-monovision procedure has scarcely been studied. The aim of this pilot study was to evaluate the efficacy of SMILE combined with different levels of micro-monovision in presbyopic patients and to assess the binocular summation effect on contrast sensitivity defocus curves (CSDC) at the 6-month follow-up. Efficacy was assessed on the basis of visual acuity (VA) and stereopsis at far, intermediate, and near distances. Patient-reported outcomes (PROs) and binocular CSDC were also evaluated. Six patients completed the study with a programmed median anisometropia of 0.81 Diopter. The median binocular uncorrected VA was better than 0 logMAR at the three evaluated distances, and stereopsis was not impaired in any patient, achieving a median of ≤119 arcsec at any distance. CSDC increased binocularly after surgery, significantly in the range of -2 to -3 D (p < 0.05). No clinically relevant changes were observed in PROs compared with the preoperative period, and all patients achieved spectacle independence at intermediate/near distance and were likely or very likely to undergo the same surgery. In conclusion, micro-monovision with SMILE could be an effective procedure, with results that might be comparable to other laser correction techniques specifically designed for presbyopia correction.

Phototherapeutic Keratectomy for Salzmann's Nodular Degeneration. What Effect Does the Choice of Excimer Laser Have on Treatment Success?

The aim of this study was to assess the difference in treatment success after phototherapeutic keratectomy (PTK) for Salzmann's nodular degeneration (SND) using two excimer lasers with different specifications. 272 PTK procedures, which had been performed on 246 eyes with SND from 181 patients, were retrospectively examined in the period from 2007 to 2017. Until 2014 the excimer laser MEL70 (Carl Zeiss Meditec Vertriebsgesellschaft mbH, Oberkochen, Germany) was used for PTK following manual pannectomy, and after 2014 the excimer laser Amaris 750S (Schwind eye-tech-solutions GmbH, Kleinostheim, Germany) was used. Treatment success was assessed on basis of visual acuity, refraction, and astigmatism, as well as pachymetry and endothelial cell count, recorded at the following time points: T1 = preoperative, T2 = 6-week follow-up, T3 = 6-month follow-up. The Wilcoxon-Mann-Whitney U test and the chi-square test with a significance level of 5% were used to compare the data. A significantly higher improvement of 0.17 ± 0.33 logMAR could be shown for visual acuity in the Schwind group (p < 0.013) after 6 months. In the Zeiss group, visual acuity improved by only 0.11 ± 0.36 (logMAR p < 0.057). Regarding refraction, a significant reduction of the spherical equivalent (SEQ) (p < 0.001) by 3.35 ± 2.76 diopters (D) after 6 months could only be shown for the Schwind group. SEQ did not change significantly in the Zeiss group (p < 0.676). The topographic astigmatism was significantly improved after 6months in both study groups, by 1.73 ± 1.99 D in the Schwind group (p < 0.001) and by 1.99 ± 2.21 D in the Zeiss group (p < 0.0001). Haze had to be treated in 12.7% of the cases in the Schwind group and in 16.2% of the cases in the Zeiss group. No endothelial cell damage was found in either group. In both study groups, the patients with SND clearly benefited from PTK. However, a significantly higher advantage for visual acuity and refraction was shown for the Schwind group compared with the Zeiss group. In contrast to the usual hyperopic effect of PTK in other diagnoses, PTK in SND showed a "myopic shift", which can be explained by the often midperipheral SND nodes and the associated asymmetric tear film pooling prior to surgery.

Role of high dose intravenous methylprednisolone and visual evoked potential (VEP) in the management of methyl alcohol poisoning: A case series report

To study the effectiveness of high dose intravenous methylprednisolone and to discuss the role of visual evoked potential (VEP) as a marker of severity and of improvement in methyl alcohol poisoning.In an outbreak of methanol poisoning, a total of six patients presented to JNMCH, AMU. Meticulous history was taken followed by examination. They were treated with high dose IV methyl prednisolone and later underwent visual evoked potential testing. The patients were examined daily till the time of discharge and then followed up at 1 month.Following treatment with high dose IV methyl prednisolone, 100% of cases showed improvement in vision which was judged on the basis of visual acuity and visual evoked potential assessment at the time of presentation. As recorded by VEP, 4 patients (66.6%) had prolonged P100 latency while no response was recorded in 2 patients (33.3%). In 3 (50%) of the 6 cases, improvement in visual acuity of at least two lines of Snellen chart was observed at 1 month follow-up while two patients (33.3%) improved from doubtful light perception to counting fingers at least 2 metres and one patient (16.6%) improved from perception of light present to counting finger at least 2 metres.Early presentation and timely intervention improves visual outcome in methanol poisoning. High-dose IV methylprednisolone seems to have benefits in the treatment of methanol optic neuropathy. The VEP examination appears to be a sensitive marker for diagnosis and prognosis of even subclinical impairment of the optic system due to methanol poisoning.

Comparison of intravitreal injections of Ranibizumab and Aflibercept in neovascular age related macular degeneration

ABSTRACT Clinical relevance: Pivotal studies are based on strict treatment regimens of vascular endothelial growth factor blocking drugs in neovascular age-related macular degeneration. However, looser regimens with poorer results have been reported in real-world studies with various outcomes. This results in a search of more precise data to rely on in the management of patients with neovascular age-related macular degeneration. Background: The aim of this study is to analyse the real-world outcome of vascular endothelial growth factor blocking agents in neovascular age-related macular degeneration. Methods: This is a retrospective comparative study of treatment-naïve patients who received intravitreal aflibercept or ranibizumab administration for neovascular age-related macular degeneration for at least 12 months on an as needed regimen following a loading phase of three-monthly injections. Full eye examination and optical coherence tomography scans were provided at all visits. The drugs were compared on the basis of visual acuity, central macular thickness, and subfoveal choroidal thickness. The baseline optical coherence tomography features were analysed seeking a correlation with the outcome. Results: One hundred and forty-one eyes were enrolled. The mean age was 71.7 ± 8.5 years. Sixty-eight (48.2%) patients received aflibercept and 73 (51.8%) received ranibizumab injections. The mean number of injections was 6.5 ± 2.5. The mean number of injections were also similar between groups (6.4 ± 2.5 vs. 6.5 ± 2.6, respectively, p = 0.783). At one year, both drugs caused significant increase in visual acuity and decrease in central macular thickness and subfoveal choroidal thickness. Conclusion: In a real-world setting, aflibercept and ranibizumab yielded similar results at one year in the management of neovascular age-related macular degeneration.

Micropulse Transscleral Cyclophotocoagulation: A Look at Long-Term Effectiveness and Outcomes

To investigate the long-term effectiveness of intraocular pressure (IOP) and medication reduction in patients who have undergone micropulse transscleral cyclophotocoagulation (mTS-CPC). Retrospective chart review. A total of 73 eyes of 62 patients treated no more than 1 time with mTS-CPC in a practice in New York City with at least 1 year of follow-up. Treatment was 100 seconds of mTS-CPC with energy titrated on the basis of visual acuity. Paired t test and multivariable analysis were performed with SAS (SAS Institute Inc, Cary, NC). Visual acuity, IOP, medication burden, phthisis, and development of macular edema were followed. Average initial IOP was 25.5±9.4, and average number of initial medications was 3.1±1.1. At 1 year, average IOP was 13.8±7.0 (46% reduction) and average number of medications was 2.5±1.0 (19% reduction). A total of 11 of 15 patients (73.3%) initially taking an oral carbonic anhydrase inhibitor before CPC did not require the oral carbonic anhydrase inhibitor 1 year after treatment. Seventy-six percent of patients obtained at least 20% IOP reduction. Multivariate analysis found IOP reduction was associated with power used and preoperative IOP, whereas medication reduction was associated with initial medication burden. Notably, there was a 57% reduction in IOP at 2500 mW power and a 30% reduction at 2000 mW power. No patients developed macular edema or phthisis from the procedure. Some 18.8% of patients with 20/400 vision or better experienced persistent vision loss of ≥2 lines after the procedure, and 10% of patients with light perception to count finger vision progressed to no light perception (NLP) after the procedure. Of patients with 20/400 vision or better, 12.5% gained ≥2 lines of visual acuity on the Snellen chart at the postoperative year 1 visit. In addition, 15.4% of patients with count fingers to NLP vision improved at the postoperative year 1 visit after treatment. One of 6 patients (16.7%) with NLP gained vision at the postoperative year 1 visit. This study provides evidence that mTS-CPC is a clinically useful procedure associated with good long-term medication burden reduction and IOP reduction that follows a dose-response pattern related to power used.

The macular function and structure in patients with diabetic macular edema before and after ranibizumab treatment.

PurposeTo evaluate macular function and structure in patients with diabetic macular edema prior to, as well as 3 and 6 months after intravitreal ranibizumab treatment.Patients and methodsSeventeen eyes of 17 patients with type 2 diabetes mellitus and diabetic macular edema (DME) were treated with intravitreal injections of 0.5 mg ranibizumab. Prior to the first injection, as well as after 3 and 6 months, the following examinations were performed: assessment of distance best-corrected visual acuity (log MAR), perception of metamorphopsia (M-Chart), slit lamp examination of the anterior and posterior segment of the eye (Volk 90D lens), evaluation of the retinal and choroidal circulation (fluorescein angiography), assessment of the structure and thickness of the macula (OCT), as well as evaluation of the macular function (PERG and mfERG). ResultsWe observed that ranibizumab significantly improved visual acuity after 3 and 6 months from the beginning of the treatment, which was a consequence of reduced macular edema and vascular leakage. There was a statistically significant decrease in metamorphopsia frequency at month 3; however, at month 6 it was a statistically insignificant when compared to the baseline. The results of electrophysiological examinations revealed no improvement in ranibizumab-treated patients.ConclusionImprovement of visual acuity and reduction in macular thickness were maintained up to the 6-month follow-up. The results of electrophysiological examinations revealed that ranibizumab injections tend to stabilize bioelectrical macular function of the outer, middle and inner retinal layers, which was impossible to recognize on the basis of visual acuity and OCT. Therefore, the electrophysiological examinations should be used as an additional objective tool for the evaluation of the anti-VEGF treatment effectiveness in DME.

Factors affecting visual loss and visual recovery in patients with pseudotumor cerebri syndrome

To investigate the frequency of visual loss (VL), possible predictive factors of VL, and improvement in patients with pseudotumor cerebri (PTC) syndrome. We reviewed 50 PTC patients (43 females, seven males) who underwent neuro-ophthalmic examination at the time of diagnosis and after treatment. Demographic data, body mass index (BMI), time from symptom onset to diagnosis (TD), maximum intracranial pressure (MIP), occurrence of cerebral venous thrombosis (CVT), and treatment modalities were reviewed. VL was graded as mild, moderate, or severe on the basis of visual acuity and fields. Predictive factors for VL and improvement were assessed by regression analysis. The mean ± SD age, BMI, and MIP were 35.2 ± 12.7 years, 32.0 ± 7.5 kg/cm2, and 41.9 ± 14.5 cmH2O, respectively. Visual symptoms and CVT were present in 46 and eight patients, respectively. TD (in months) was <1 in 21, 1-6 in 15, and >6 in 14 patients. Patients received medical treatment with (n=20) or without (n=30) surgery. At presentation, VL was mild in 16, moderate in 12, and severe in 22 patients. Twenty-eight patients improved and five worsened. MIP, TD, and hypertension showed a significant correlation with severe VL. The best predictive factor for severe VL was TD >6 months (p=0.04; odds ratio, 5.18). TD between 1 and 6 months was the only factor significantly associated with visual improvement (p=0.042). VL is common in PTC, and when severe, it is associated with a delay in diagnosis. It is frequently permanent; however, improvement may occur, particularly when diagnosed within 6 months of symptom onset.

Recent insights into perceptual and motor skill learning.

Recent insights into perceptual and motor skill learning.

Parallel universes with a universal problem

<h3>Objective:</h3> To examine the determinants of formal and informal care utilisation amongst persons with age-related macular degeneration (AMD). <h3>Design:</h3> Cross-sectional hospital-based study. <h3>Setting:</h3> Hospital eye clinic in Northern Ireland. <h3>Participants:</h3>...

Autofluorescence Imaging in Age-Related Macular Degeneration Complicated by Choroidal Neovascularization: A Prospective Study

To determine if integrity of the retinal pigment epithelium (RPE)/photoreceptor complex as assessed by autofluorescence imaging can be predicted on the basis of visual acuity (VA), size, or fluorescein angiographic characteristics of the lesion in the early stage of choroidal neovascularization in age-related macular degeneration (AMD). Prospective, observational, consecutive case series. Seventy-nine eyes of 78 patients with untreated early-stage subfoveal neovascular AMD. Digital color fundus photography and fluorescein angiography were carried out by certified photographers using the same camera throughout the study. Confocal scanning laser ophthalmoscopy images were obtained using a retinal angiograph. Autofluorescence images were compared with digital fluorescein angiography and fundus color photographs using IMAGEnet. Autofluorescence at the macula was correlated with VA, angiographic lesion characteristics, lesion size, and length of symptoms. Of the 79 eyes studied, 40 had classic and predominantly classic choroidal neovascularization, 10 had minimally classic, 29 had occult, 75 were subfoveal, and 4 were juxtafoveal. In 54 eyes, autofluorescence was continuous at the central macula, and this correlated significantly with VA, lesion size, and symptom length but not choroidal neovascularization type. However, there was considerable overlap between the 2 groups such that the integrity of RPE autofluorescence could not be predicted on the basis of these criteria. Intact autofluorescence at the macula in early choroidal neovascularization correlates with VA, lesion size, and symptom length but not lesion type. None predict with any certainty the integrity of the outer retina. Our data suggest that the RPE/photoreceptor complex may be intact at the macula for several months in the presence of choroidal neovascularization, suggesting that VA might be rescued if treatment were effective in suppressing neovascular growth without damaging the RPE/retina complex, although this remains to be tested. It would be sensible to assess autofluorescence in treatment protocols to test this concept because it may be a marker for earlier disease and predict outcomes of treatment.

Formal and informal care utilisation amongst elderly persons with visual impairment

Objective:To examine the determinants of formal and informal care utilisation amongst persons with age-related macular degeneration (AMD).Design:Cross-sectional hospital-based study.Setting:Hospital eye clinic in Northern Ireland.Participants:284 persons aged ⩾50 years.Main outcome measures:Participants...

Visual risk factors for crash involvement in older drivers with cataract.

The Impact of Cataracts on Mobility project has previously demonstrated that older drivers with cataract have an elevated risk of motor vehicle collision. To examine what types of visual impairment serve as a basis of the increased crash risk of older drivers with cataract. A cross-sectional analysis was performed on 274 older drivers with cataract and 103 older drivers free of cataract recruited through 12 eye care clinics for the purposes of the Impact of Cataracts on Mobility project, a prospective study on driving mobility in older adults with cataract. Tests measured visual acuity, contrast sensitivity, and disability glare for each eye separately using habitual distance correction. The dependent variable was involvement in at least 1 state-recorded, at-fault vehicle crash during the 5 years prior to study enrollment. Logistic regression evaluated associations (odds ratios [ORs]) between visual function and crash involvement. Better and worse eye models defined on the basis of visual acuity were developed. Associations between each type of visual function and crash involvement were adjusted for age, sex, driving exposure, cognitive status, and other types of visual function. For both the better and worse eye models, contrast sensitivity was independently associated with crash involvement, whereas visual acuity and disability glare were not. Drivers with a history of crash involvement were 8 times more likely to have a serious contrast sensitivity deficit in the worse eye (defined as a Pelli-Robson score of 1.25 or less) than those who were crash-free (OR = 7.86; 95% confidence interval [CI], 1.55-39.79); this association was weaker for the better eye but still statistically significant (OR = 3.78; 95% CI, 1.15-12.48). Crash-involved drivers were 6 times more likely to have severe contrast sensitivity impairment in both eyes (OR = 5.78; 95% CI, 1.87-17.86) than crash-free drivers. A severe contrast sensitivity deficit in only 1 eye was still significantly associated with crash involvement (OR = 2.70; 95% CI, 1.16-6.51). Severe contrast sensitivity impairment due to cataract elevates at-fault crash risk among older drivers, even when present in only 1 eye.

A Fluorescem Angiographic Study of Patients with Pars Planitis and Peripheral Exudation (snowbanking) before and after Cryopexy

Transconjunctival cryopexy of the vitreous base is clinically effective in patients with steroid nonresponsive pars planitis who have peripheral neovascularization. Cryoablation of the region previously has been thought to eliminate the areas of permeable neovascular tissue, thus removing the focus of exudation. The authors report the first study of patients with refractory pars planitis in which fluorescein angiography of the inferior pars plana snowbanks was performed both before and after cryopexy of the vitreous base. Twelve consecutive phakic eyes with pars planitis and prominent peripheral snowbanks had fluorescein angiograms of the pars plana. Clinical involvement was graded on the basis of visual acuity, levels of vitreous inflammation and cystoid macular edema, and on the extent of peripheral snowbanking. Transconjunctival cryopexy of the vitreous base was performed. Fluorescein angiography of the pars plana snowbanks was repeated 2 months after the procedure, and clinical involvement again was graded. Early hyperfluorescence with late leakage was present in all eyes and was limited to the area of the pars plana snowbanks. After cryopexy of the vitreous base, all eyes demonstrated hypofluorescence and diminution of late-phase dye leakage in the treated areas. Eighty-three percent of all eyes demonstrated clinical improvement, consistent with previously reported studies. Cryopexy of the vitreous base decreases peripheral exudation in patients with refractory pars planitis and snowbanking. This suggests that elimination of peripheral neovascular tissue may be directly related to clinical improvement in these patients.

Molecular and cellular basis of visual acuity Edited by ?, 184 pp., 72 figs, Springer, New York, 1984, DM 98, approx. US$38.50.

Molecular and cellular basis of visual acuity Edited by ?, 184 pp., 72 figs, Springer, New York, 1984, DM 98, approx. US$38.50.

Contrast sensitivity in evaluation of visual impairment due to diabetes.

Spatial contrast sensitivity of 19 diabetics with different degrees of visual impairment was studied. It was found that contrast sensitivity at intermediate and low spatial frequencies may decrease without corresponding loss of visual acuity. In advanced cases of diabetes the opposite may be true: contrast sensitivity was better than expected on the basis of visual acuity. Thus both visual acuity and contrast sensitivity measurements are useful in the evaluation of the nature of visual impairment due to diabetic eye disease.

Improvement in Rapid Reading as Related to Visual Acuity and Initial Reading Speed

College freshmen enrolled in a rapid reading course were assigned to one of two groups on the basis of visual acuity. These groups were further divided on the basis of their pretest reading speed. Reading speed and compre hension measures were taken before, after, and periodically throughout the course. Results indicated that the in crease in reading speed of the myopic group was significantly greater than that of the emmetropic group and that the group reading initially faster improved at a more rapid rate than did the slower group. Comprehension de creased during the course with the fast readers maintaining better comprehension. By the final measure, reading speed was more related to visual acuity than to the individual's initial reading speed. The results were interpreted as supporting the contention that myopes are more visually oriented.

The physiological basis of visual acuity.

The physiological basis of visual acuity.