Age-Specific Changes in the Prevalence of Best-Corrected Visual Impairment in an Italian Population

Purpose: To investigate changes in the prevalence of visual impairment in an Italian population from 1988 to 2000. Methods: Standardized ophthalmologic examinations were administered to citizens of Ponza, Italy aged 40–87 years in 1988 and 2000. Visual Acuity (VA) was measured using a standard logarithmic chart. Visual fields (VF) were tested in all subjects with diagnosed or suspected glaucoma or hereditary degenerative retinopathy. Visual impairment was classified as blindness (VA > 1.3 LogMAR or VF < 10° around central fixation) or low vision (VA > 0.5 to 1.3 LogMAR or VF < 20° to 10°) according to WHO criteria. Results: The prevalence of binocular total visual impairments decreased significantly among 64–75 year-olds (from 6.7% to 2.6%, p = 0.045), and almost significantly among 40–51 year-olds (from 2.4%, 95% CI 1.1–5.3, to 0.0%, 95% CI 0.0–1.3). By 2000, visual impairment was no longer significantly associated with female gender, and age 64–75 years; the mean age of subjects with vision-impairing cataract, diabetic retinopathy, or age-related macular degeneration had risen significantly. Conclusions: A decline in the prevalence of visual impairment, particularly in cataract-associated visual impairment was found in the middle-aged groups. The progression of age-related eye diseases seems to have slowed in this population possibly due to improvements in the life expectancy and socio-economic conditions.     

A Calculator for LogMAR Visual Acuity Measurements

A sliding-scale calculator is presented that indicates the conventional (6m) Snellen acuity fraction, given any logMAR chart standard viewing distance and the size of the smallest letters on that chart read correctly by a patient.     

Visual fields for frontal plane motion and for changing size

Thresholds were measured in 15 subjects for 2-Hz oscillations of size and for 2-Hz oscillatory motion in the frontal plane using test squares of side lengths 0.5°, 1.0° and 2.0°. Size-oscillation thresholds were lowest (i.e. sensitivity was greatest) for the 2.0° square while thresholds were highest (i.e. sensitivity was least) for the 0.5° square in 28 of 34 tests. Frontal plane motion thresholds, on the other hand, did not generally depend on square size. Equal-threshold contours in the visual field were roughly elliptical in 10 of 13 subjects for both types of oscillation. None of 13 subjects had visual field defects for oscillating-size or frontal plane motion, in contrast with the known incidence of stereo-motion scotomata. One subject was known to be selectively “blind” to stereoscopically-oscillating disparity in some areas of the visual field, but oscillating-size sensitivity was normal in these regions, thus preserving an alternative basis for motion-in-depth judgments.     

Alcohol Consumption,Drinking Pattern,and Self-Reported Visual Impairment

Purpose: To examine whether alcohol drinking status and drinking pattern are associated with self-reported visual impairment.

Methods: We used data from the Behavioral Risk Factor Surveillance System, a state-based telephone health survey conducted by random-digit dialing among non-institutionalized US adults. The Visual Impairment and Access to Eye Care module was implemented among 42, 713 adults aged 50 years and older in 2005 and 2006. Visual impairment was defined as any degree of difficulty experienced in recognizing a friend across the street or reading print in newspaper, magazine, recipe, menu, or numbers on the telephone with usual correction. Drinking patterns included drinking quantity (drinks per drinking day), frequency (drinking days in the past month), and binge drinking.

Results: After adjustment for age, sex, race/ethnicity, educational attainment, smoking status, Body Mass Index, history of cardiovascular diseases, diabetes, and eye diseases, current drinking status was not associated with distance and/or near vision impairment. However, drinking more than 1 drink per drinking day (odds ratio [OR], 1.21; 95% confidence intervals [CI], 1.09–1.35) and binge drinking (OR, 1.32; 95% CI, 1.14–1.53) were associated with visual impairment among current drinkers.

Conclusion: Among current drinkers, drinking patterns were significantly associated with near and distance vision impairment. Longitudinal studies are needed to confirm whether drinkers who drink beyond drinking guidelines, especially binge drinkers, are at higher risk of visual impairment than those who drink at lower levels.     

The Parameters of Pattern Visual Evoked Potential in the Severe Visual Loss Patients in Korean

PurposeTo compare the characteristics of the pattern visual evoked potential (PVEP) in patients with severe visual loss and normal controls, and to demonstrate the range of PVEP parameters in normal Koreans.MethodsThe patients were divided into three groups according to visual acuity: group 1, ranging from no light perception to less than 0.02; group 2, ranging from 0.02 to 0.1; and group 3, ranging from 0.125 to 0.25. Group 4 was established as a healthy control group. The 95% confidence intervals (CIs) of the PVEP parameters were calculated for group 4. The PVEP parameters were compared among these four groups, and the amplitudes were evaluated with respect to the 95% CIs. We used the area under the curve to integrate the sensitivity and the specificity of the PVEP parameter quantitative values (7.01 to 9.57 µV and 6.75 to 10.11 µV).ResultsA total of 101 eyes were investigated. The 95% CIs of the P100 and N135 amplitudes of group 4 were 7.01 to 9.57 µV and 6.75 to 10.11 µV, respectively. The amplitudes of P100 and N135 were significantly higher in group 4 (p < 0.001). The P100 and N135 amplitude were below the 95% CI in all group 1 patients. The area under the curve of the P100 amplitude was the highest (0.789).ConclusionsNo legally blind patient in the present study exhibited a value within the 95% CI of the controls. The P100 amplitude may be the best parameter for defining blindness in patients.     

Visual information processing in recently abstaining methamphetamine-dependent individuals: evoked potentials study

Objective Methamphetamine (MAP) is an indirect dopamine agonist that can temporarily increase cognitive performance. However, its long-term abuse may cause dopamine depletion and consequent cognitive and attentional impairment. The worsening of visual functions in Parkinson’s disease and their improvement after levodopa administration implicates the role of dopamine in the physiology of vision. This provides the rationale for the investigation of visual functions in abstaining MAP abusers. Methods We investigated changes in visually evoked potentials (VEPs) to pattern-reversal and motion-onset stimuli. Such changes serve as indices of visual information processing in the primary and associative areas in a group of recently abstaining MAP abusers (5 females, 18 males, MAP abuse 5.3 ± 2.8 years) and in 23 age- and gender-paired controls. Results We did not find differences between the groups in visual acuity. In the group of MAP abusers we observed an attenuation of the early responses around 80 ms and a prolongation of the P1 peak latency after the reversal of high spatial frequency checkerboards (10 and 20 arcmin checks). Furthermore, an attenuation of the latter positive response (170–250 ms) was observed among all the stimuli in parieto-frontal derivations for the MAP abusers. Conclusions This is the first report suggesting a slowing and attenuation of VEP responses during visual processing in abstaining methamphetamine abusers.     

Multifocal Visual Evoked Responses to Dichoptic Stimulation Using Virtual Reality Goggles: Multifocal VER to Dichoptic Stimulation

Multifocal visual evoked potentials (mfVEPs) have demonstrated good diagnostic capabilities in glaucoma and optic neuritis. This study aimed at evaluating the possibility of simultaneously recording mfVEP for both eyes with dichoptic stimulation using virtual reality goggles and also to determine the stimulus characteristics that yield maximum amplitude. ten healthy volunteers were recruited and temporally sparse pattern pulse stimuli were presented dichoptically using virtual reality goggles. Experiment 1 involved recording responses to dichoptically presented checkerboard stimuli and also confirming true topographic representation by switching off specific segments. Experiment 2 involved monocular stimulation and comparison of amplitude with Experiment 1. In Experiment 3, orthogonally oriented gratings were dichoptically presented. Experiment 4 involved dichoptic presentation of checkerboard stimuli at different levels of sparseness (5.0 times/s, 2.5 times/s, 1.66 times/s and 1.25 times/s), where stimulation of corresponding segments of two eyes were separated by 16.7, 66.7,116.7 & 166.7 ms respectively. Experiment 1 demonstrated good traces in all regions and confirmed topographic representation. However, there was suppression of amplitude of responses to dichoptic stimulation by 17.9±5.4% compared to monocular stimulation. Experiment 3 demonstrated similar suppression between orthogonal and checkerboard stimuli (p = 0.08). Experiment 4 demonstrated maximum amplitude and least suppression (4.8%) with stimulation at 1.25 times/s with 166.7 ms separation between eyes. It is possible to record mfVEP for both eyes during dichoptic stimulation using virtual reality goggles, which present binocular simultaneous patterns driven by independent sequences. Interocular suppression can be almost eliminated by using a temporally sparse stimulus of 1.25 times/s with a separation of 166.7 ms between stimulation of corresponding segments of the two eyes.     

视觉虚拟现实训练与传统训练方法治疗儿童弱视的比较

目的：比较视觉虚拟现实训练与传统训练方法治疗儿童弱视的疗效。方法：前瞻性随机对照试验。 选取2018年6月至2019年12月于武汉大学中南医院确诊的并首次接受治疗的3～12岁弱视患儿90例 （146眼）,虚拟组45例（74眼）,传统组45例（72眼）。在屈光矫正及定量遮盖的基础上,虚拟组采用视 觉虚拟现实训练方法治疗,传统组采用传统训练方法治疗,时间为3个月,比较2组患儿治疗前后视 力及立体视的变化。采用t检验或秩和检验、χ2 检验及Fisher确切概率对数据进行分析。结果：虚拟组 总有效率87%,传统组总有效率68%,2组比较差异有统计学意义（χ2 =7.086,P=0.008）。3～6岁,虚 拟组有效率91%,优于传统组74%（χ2 =4.652,P=0.031）;7～9岁和10～12岁患儿,虚拟组和传统组之 间差异无统计学意义;轻度弱视患儿,虚拟组有效率为92%,优于传统组的75%（χ2 =2.908,P=0.018）; 中度、重度弱视患儿,虚拟组和传统组之间差异无统计学意义;屈光不正性弱视患儿,虚拟组有效 率为89%,传统组为74%,差异无统计学意义;屈光参差性弱视患儿,虚拟组有效率为85%,传统 组为57%,差异有统计学意义（χ2 =3.840,P=0.045）。在治疗后1、2、3个月后虚拟组有效率为43%、 54%和87%,持续高于传统组的24%、40%和68%,差异有统计学意义（χ2 =6.308,P=0.012;χ2 =2.779, P=0.016;χ2 =7.086,P=0.008）;3个月后,虚拟组立体视觉正常者比例为72%,高于传统组61%（χ2 =8.214, P=0.004）。结论：视觉虚拟现实训练较传统方法治疗儿童弱视疗效更显著,特别是对3～6岁轻度的 屈光参差性弱视;该方法不仅可以较快提高患儿视力,还有助于双眼立体视觉的改善。     

Comparison of Visual Virtual Reality Training and Traditional Treatment for Childhood Amblyopia

Objective: To compare the clinical effects of a visual virtual reality training system and a traditional method for amblyopia in children. Methods: This was a prospective, randomized, controlled study. A total of 90 children (146 eyes) from 3 years to 12 years of age underwent treatment for amblyopia for the first time. They were divided into an experimental group (45 cases, 74 eyes) and control group (45 cases, 72 eyes). Children in the experimental group had treatment with a visual virtual reality training system, and the control group had conventional integrated therapy. Visual tests were conducted every month, and a stereopsis examination was conducted after 3 months. The efficacy and safety of the visual virtual realitytraining method was evaluated by comparing the effects for the two groups. Data were analyzed using t test, rank sum test, Chi-square test and Fisher exact test. Results: The total effective rate for the experimental group was 87%, and was 68% for the control, and the difference was significant (χ2 =7.086, P=0.008). The results were significantly different for the patients in the 3 to 6 age group (91% vs. 74%, χ2 =4.652, P=0.031). For mild amblyopia, the effective rate was 92% in experimental group, which was significantly better than the 75% in control group (χ2 =2.908, P=0.018). For anisometropic children the effective rate in the experimental group was significantly better than the rate in the control group (85% vs. 57%, χ2 =3.840, P=0.045). When the effective rates for the two treatments were compared at 1, 2 and 3 months, the effective rates in the experimental group (43%, 54% and 87%) were significantly better than the rates in the control group (24%, 40% and 68%) (χ2 =6.308, P=0.012; χ2 =2.779, P=0.016; χ2 =7.086, P=0.008). When stereopsis was compared after 3 months, stereopsis in the experimental group (72%) was better than that in the control group (61%)(χ2 =8.214, P=0.004). Conclusions: The efficacy of visual virtual reality training is better than traditional treatment, especially for children 3 to 6 years of age and for anisometropia amblyopia. Visual virtual reality training cannot only improve visual acuity, it helps to improve stereopsis as well.     

单焦点IOL植入术后RGPCL诱导屈光参差后的视觉质量

目的探讨在年龄相关性白内障手术中,应用单眼视概念,双眼植入不同度数单焦点人工晶状体（IOL）的可行性。方法前瞻性非随机临床对照研究。选取双眼白内障摘除联合单焦点IOL植入术后符合标准的患者40例（80眼）,做2种矫正处理：以硬性透氧性角膜接触镜（RGPCL）一眼矫正为正视,一眼矫正为-2.0 D近视,即屈光参差状态或双眼矫正为正视,即全矫状态。分别检测其远方三级视功能、近立体视及远、近对比敏感度,并对生活满意度进行调查评估。对数据进行配对t检验,配对符号秩和检验或χ2检验。结果立体视检查显示：矫正状态远融合功能、立体视优于屈光参差状态（χ2=9.03、16.88,P<0.01）,屈光参差状态的近立体视优于矫正状态,差异有统计学意义（Z=-3.230,P<0.01）。但屈光参差状态仍有相当数量患者存在远立体视,矫正状态有近立体视患者数量较少。对比敏感度检查显示：在低频段,无论明亮还是昏暗条件,2种状态下远近对比敏感度差异无统计学意义;在中高频段,矫正状态远对比敏感度优于屈光参差状态（t=0.37、0.51、0.35、0.46、0.44、0.46、0.51、0.40,P<0.01）,而屈光参差状态近对比敏感度优于矫正状态（t=0.18、0.34、0.49、0.38、0.20、0.34、0.24、0.38,P<0.01）。生活质量调查显示,屈光参差状态总体视力满意度较全矫状态高,差异有统计学意义（t=-3.05,P<0.01）。结论年龄相关性白内障术后双眼诱导屈光参差,视远视觉质量下降,但仍有相当数量患者存在远立体视,视近视觉质量明显提高,生活满意度提高。     

The Impact of Visual Impairment on Completion of Cognitive Screening Assessments: A Post-Hoc Analysis from the IVIS Study

Aim:The aim of this study was to evaluate completed cognitive screens in stroke survivors with and without visual impairment to explore whether the presence of visual impairment impacts on completion of cognitive screening.Materials and methods:Cognitive screening assessment was undertaken using the Oxford Cognitive Screen (OCS). Data from visual function assessments (inclusive of visual acuity, visual fields, eye movements and visual perception evaluation) were analysed to determine whether presence and/or type of visual impairment impacted on cognitive screening scores achieved. Covariates, including glasses use, gender, age at stroke onset and stroke type, were used to assess confounding impacts on scores attained during cognitive screening.Results:1500 stroke admissions were recruited. One hundred ninety-seven who completed the OCS, were identified from the IVIS study database. Those who reported visual symptoms performed worse statistically on all cognitive tasks except the recall recognition (p = 0.232) and executive tasks (p = 0.967). Visual symptoms did not prevent participants from completing every section of the OCS (p = 0.095). In certain tasks, those not wearing their required glasses performed worse, including the executive function (p = 0.012), broken hearts and sentence reading tasks.Conclusions:Many tasks within cognitive screening assessment are impacted by presence of visual deficits, and adjustments, where possible (e.g. good lighting, large print) should be used to facilitate completion of cognitive screening. It is important to ensure required reading correction is worn during screening.     

Visual Field Defects Following an Uncomplicated Coil Embolisation of a Carotid-Ophthalmic Aneurysm

A carotid-ophthalmic aneurysm often causes ocular symptoms and signs not only because of subarachnoid haemorrhage due to ruptured aneurysm but also because of the anatomical location, a proximity to the optic apparatus and ophthalmic artery. In addition, the permanent vision loss may be developed by direct injury to optic nerve and ophthalmic artery after surgical treatment. Recently, endovascular treatments such as coil embolisation have been frequently used for this aneurysm with a decreased complication. However, coil embolisation may rarely cause acute and delayed visual deterioration due to thromboembolism and perianeurysmal inflammation. The authors report two patients who early or immediately developed visual field defects following an uncomplicated coil embolisation of a carotid-ophthalmic aneurysm.     

Causes of visual impairment among patients referred to a visual rehabilitation clinic in Iran

Purpose

Epidemiologic evaluation and investigating the causes of visual impairment in any society is a matter of concern and has a direct effect on the country''s health care planning. In this study we describe causes of low vision and blindness in Iranian patients referred to rehabilitation clinics for taking vision aids.

Methods

In this cross-sectional study, visual acuity was classified based on best-corrected visual acuity in the better eye according to the World Health Organization definition (blindness, visual acuity [VA] < 20 / 400; severe visual impairment, VA < 20 / 200-20 / 400; mild to moderate visual impairment, VA < 20 / 60-20 / 200). The causes of blindness and low vision were determined using the 10th version of International Classification of Diseases based on the main cause in both eyes. To describe data, we used mean ± SD and frequency.

Results

The study included 432 patients, 65% male, with a mean age of 43.6 ± 25.5 years (range, 3 to 92 years). Mild to moderate visual impairment, severe visual impairment and blindness were present in 122 (28.8%), 196 (46.4%) and 105 (24.8%) of the patients, respectively. The main causes of visual impairment were retinal and choroidal diseases (74.5%), optic nerve and optic tract diseases (9.8%), vitreous and globe disorders (5.3%), congenital cataract (3.1%), and glaucoma (2.6%). The distribution pattern of the causes was similar in all age subgroups.

Conclusions

Diseases of the retina and choroid are the main cause of visual impairment among patients referred to an academic visual rehabilitation clinic in Iran.     

Visual Loss Due to Wernicke Syndrome Following Gastric Bypass

Purpose: To report a case of Wernicke encephalopathy after gastric bypass surgery resulting in vision loss, ophthalmoplegia, and ataxia, all of which reversed with a single dose of IV thiamine. Methods: Observational case report. Results: A 34-year-old woman presented with decreased vision and intermittent diplopia after gastric bypass surgery. She was found to have bilateral limitation of horizontal gaze, decreased vision with bilateral central scotoma and mild disc edema OU. Her cranial magnetic resonance imaging (MRI) was normal. A presumptive diagnosis of Wernicke encephalopathy was made. The patient was admitted, and a single dose of IV thiamine reversed the ophthalmoplegia and vision loss within 24 hours. Conclusion: Wernicke encephalopathy should be considered in patients with vision loss after gastric bypass surgery. The classic triad of confusion, ataxia, and ophthalmoplegia may not be present and, although uncommon, the findings of optic disc edema and vision loss should not deter the clinician from making the diagnosis. Replacement thiamine if given promptly may rapidly reverse the findings.     

重视后视路损伤的治疗与视功能的康复

累及后视路的脑卒中、脑肿瘤及脑外伤所导致同向偏盲性视野缺损在临床上很常见.尽管部分患者在损伤早期视野有部分改善,但是仍严重影响患者日常生活工作能力.国外系列研究显示以“残余视觉理论”和“脑塑形”为基础的视觉重建治疗可以通过扩大患者视野改善视功能.尽管目前国际上对视觉重建治疗效果和机制还存在较大争论,但由于视路损害所致视...     

Visual acuity testing. From the laboratory to the clinic

The need for precision in visual acuity assessment for low vision research led to the design of the Bailey–Lovie letter chart. This paper describes the decisions behind the design principles used and how the logarithmic progression of sizes led to the development of the logMAR designation of visual acuity and the improved sensitivity gained from letter-by-letter scoring. While the principles have since been adopted by most major clinical research studies and for use in most low vision clinics, use of charts of this design and application of letter-by-letter scoring are also important for the accurate assessment of visual acuity in any clinical setting. We discuss the test protocols that should be applied to visual acuity testing and the use of other tests for assessing profound low vision when the limits of visual acuity measurement by letter charts are reached.     

Visual search is guided to categorically-defined targets

To determine whether categorical search is guided we had subjects search for teddy bear targets either with a target preview (specific condition) or without (categorical condition). Distractors were random realistic objects. Although subjects searched longer and made more eye movements in the categorical condition, targets were fixated far sooner than was expected by chance. By varying target repetition we also determined that this categorical guidance was not due to guidance from specific previously viewed targets. We conclude that search is guided to categorically-defined targets, and that this guidance uses a categorical model composed of features common to the target class.     

Visual search training in subjects with severe to profound low vision

Effects of practicing on feature search tasks (a 2 degrees square target amid 1 degrees square distracters) for 5 days were compared between 45 visually impaired (VI) subjects with severe to profound low vision and 23 age-matched normal controls (NV). Search accuracy and speed improved in both groups. VI subjects had larger training gains than NV subjects, but their proportional gains were similar to that of NV subjects. There were no significant differences in training effect at different set sizes in both groups. Search performance on a 40 degrees field improved more than that on a 10 degrees or 20 degrees field in VI subjects, but not in NV subjects. No significant change was found between day 5 and 1-month follow-up. The fact that feature search training is equally efficient in VI and NV subjects encourages development of general purpose perceptual training protocols for low vision rehabilitation.     

Acute Bilateral Visual Loss Related to Orthostatic Hypotension

A 50-year-old man had undergone lumbar vertebral surgery and was confined to bed in the supine position for three months. When he sat up from the prolonged supine position, he showed clinical signs of orthostatic hypotension and reported decreased vision in both eyes. He also had underlying anemia. Ophthalmologic findings suggested bilateral anterior ischemic optic neuropathy (ION) as the cause of the visual loss. Although there are numerous reports of ION in the setting of hemodynamic compromise, such as systemic hypotension, cases of ION-associated orthostatic hypotension are very rare.     

Using a Computerised Staircase and Incremental Optotype Sizes to Improve Visual Acuity Assessment Accuracy

Background:Given the impact of visual acuity results on diagnosis and management, it is essential that the test is accurate, determined by factors such as test-retest variability. Standardisation improves accuracy, which can be performed via a computerised staircase methodology. Standard clinical tests with scoring of 0.02 per optotype implies an incremental score per optotype despite optotype size remaining constant on each line. The aim of this study is to establish if near continuous incremental optotype display and scoring improves test-retest variability compared to current testing methods.Methods:A computerised three up, one down adaptive staircase was used to display Kay Picture optotypes on an LCD monitor. Three methods of visual acuity assessment were undertaken: ETDRS, Kay Pictures and computerised Kay Pictures. Tests were performed twice under standard clinical conditions.Results:One hundred nineteen adults were tested. Test-retest variability for computerised Kay pictures was 0.01 logMAR (±0.04, p = 0.001). Good levels of agreement were observed for computerised Kay pictures in terms of test-retest variability, where the test had the smallest mean bias (0.01 logMAR compared to 0.03 and 0.08 logMAR for Kay Pictures and ETDRS respectively) and narrowest limits of agreement. Participants performed better in computerised Kay pictures than Kay Pictures by 0.03 logMAR, and better in ETDRS than computerised Kay pictures by 0.1 logMAR.Conclusion:Computerised Kay pictures exhibited a low test-retest variability, demonstrating it is reliable and repeatable. This repeatability measure is lower than the test-retest variability of the ETDRS and Kay Pictures tests.