SEARCH · PubMed Health

Results for “Visual Acuity”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources

PubMed2000

Visual acuity in children with coloboma: clinical features and a new phenotypic classification system.

OBJECTIVE: The aims of this study were to describe the clinical features and biometric findings in the eyes of children with coloboma and to develop a classification of coloboma that correlates with visual function. DESIGN: Retrospective observational case series. PARTICIPANTS: One hundred thirteen children and young adults (48 female, 65 male) aged 0 to 20 years with 196 eyes having coloboma. METHODS: Children with coloboma were recruited from schools for the blind, integrated education programs, schools for the mentally handicapped, community-based rehabilitation services, and hospital clinics in Andhra Pradesh, India, between January 1998 and January 1999. Visual function was assessed, including distance and near visual acuity (VA), and navigational vision. The corneal diameter and axial length of eyes were measured wherever possible. MAIN OUTCOME MEASURES: Anatomic site of coloboma, association with microcornea and/or microphthalmos, VA, presence of navigational vision and reading vision. RESULTS: Of 196 eyes with colobomatous malformations, 11 had microphthalmos with cyst, and 185 eyes had coloboma (associated with microcornea in 155 eyes and with a normal corneal diameter in 30). Microphthalmos was present in 72 of the 185 eyes with coloboma, of which 71 of 72 also had microcornea. The prognosis for vision depended on the phenotype of the better eye. Microphthalmos with cyst had the worst prognosis (VA < 3/60, 100%; reading and navigational vision, 0%). Microcornea with microphthalmos had a worse prognosis than microcornea without microphthalmos (VA < 3/60: 66.7% vs. 23.3%; unable to read N10: 66.7% vs. 34.1 %; no navigational vision: 30.6% vs. 6.73%). Simple coloboma (no microcornea or microphthalmos) had the best prognosis (VA < 3/60: 6.7%; able to read N10: 93.3%; navigational vision: 100%). A corneal diameter <6 mm had a poor visual prognosis, whereas a corneal diameter >10 mm had a good prognosis. CONCLUSIONS: A phenotypic classification of coloboma is proposed, which in this study showed a good correlation with visual acuity, reading, and navigational vision. Microphthalmos with cyst had the worst prognosis, coloboma with microcornea and microphthalmos a poor prognosis, coloboma with only microcornea had an intermediate prognosis, and simple coloboma had the best prognosis.

Adolescent↗

PubMed2005

Can we utilize photorefractive keratectomy to improve visual acuity in adult amblyopic eyes?

PURPOSE: To report the results of photorefractive keratectomy (PRK) in adult amblyopic patients. DESIGN: Noncomparative case series. PARTICIPANTS: Thirty-eight amblyopic eyes of 36 adult patients who had undergone PRK ranging from -14.63 diopters (D) to +3.75 D (mean, -6.38+/-4.10) were analyzed. METHODS: Preoperative and postoperative (1, 3, and 6 months) refractions and measurements of the best spectacle-corrected visual acuity (BSCVA) were reviewed. Statistical evaluation was performed using a paired Student's t test. MAIN OUTCOME MEASURES: Best-corrected visual acuity before and after PRK. RESULTS: Before PRK, BSCVA ranged between 0.2 and 0.7 lines (mean, 0.60+/-0.13). One month after PRK, BSCVA ranged between 0.2 and 1.2 lines (mean, 0.77+/-0.24), with a significant difference (P = 3x10(-5)). Three months after PRK, BSCVA ranged between 0.15 and 1.15 lines (mean, 0.84+/-0.23), with a significant difference (P = 5x10(-7)). Six months after PRK, BSCVA ranged between 0.25 and 1.3 lines (mean, 0.88+/-0.25), with a significant difference (P = 8x10(-8)). CONCLUSIONS: Our study does not imply that refractive surgery should or may be performed in young children but, rather, that adults wishing to undergo refractive surgery may undertake such procedures despite an amblyopic eye thought to be refractory to visual rehabilitation by conventional methods, such as spectacles and contact lenses.

Adult↗

PubMed1997

[A case of pituitary apoplexy: remarkable improvement of visual acuity and field by surgical intervention at the subchronic stage].

A case is reported of a pituitary apoplexy which shows remarkable improvement of visual acuity and field by transsphenoidal surgery performed 33 days after hemorrhage. Possible factors contributing to this excellent surgical outcome are speculated about as follows; atrophic brain (wide suprasellar cistern), destruction of the sella floor by the tumor (infrasellar/extracranial decompression), no vasospasm (pure intracapsular hemorrhage), no hypopituitarism, less invasive operation (transsphenoidal surgery), and so on. Transsphenoidal surgery is thought to be worth performing for pituitary apoplexy, even if timing for the operation is later than the acute stage and even if initial visual impairment is severe.

Chronic Disease↗

PubMed1994

[Visual acuity at twilight and contrast vision in patients with bifocal IOL].

After cataract extraction by phacoemulsification, the True Vista bifocal lens (group I; Storz Ophthalmics, St. Louis, Missouri, USA) was implanted in 20 eyes, and the Accurasee bifocal lens (group II; Alcon, Forth Worth, Texas, USA) was implanted in 14 eyes. Following a 4-6 month postoperative period, both groups were checked with respect to visual acuity, mesopic acuity, and thresholds of contrast under mesopic light conditions. As mean values, group I demonstrated a distance acuity without correction of 0.77 (+/- 0.17), group II of 0.73 (+/- 0.14); the average near acuity without correction in group I was 0.84 (+/- 0.17), and in group II, 0.85 (+/- 0.15). The near acuity, with distance correction only, was determined to be 0.94 (+/- 0.09) in group I, and 0.91 (+/- 0.01) in group II. Examination of mesopic visual acuity by means of the Mesoptometer II (Oculus Company, Dutenhofen) revealed 0.25 (+/- 0.08) for the True Vista bifocal lens, and 0.26 (+/- 0.07) for the Accurasee bifocal lens. Under reduced field luminance, both groups of lenses showed comparable results while testing contrast thresholds were under 0.1 cd/m2; under 0.032 cd/m2 and 0.1 cd/m2 with permanent glare, however, group I demonstrated a slight advantage.

Contrast Sensitivity↗

PubMed1981

Disparate diameter grafting. Astigmatism, intraocular pressure, and visual acuity.

We studied 180 consecutive corneal transplants performed by one surgeon to determine the benefit obtained by using a 0.5 mm oversize (OS) graft. We compared 61 same size (SS) grafts to 119 oversize (OS) grafts, with a mean follow-up time of 24 and 13 months respectively. While the refractive error, recovery of visual acuity, and intraocular pressure were similar in both groups, the astigmatism was found to be significantly elevated in the (OS) group. Using a 0.5 mm oversize graft did not afford any protection against postkeratoplasty glaucoma, did not increase the speed of recovery of the patients' visual acuity, but produced significantly more astigmatism than a same size graft.

Adult↗

PubMed2001

Visual acuity assessment in infants and young children.

The accurate and reliable assessment of visual function in infants and young children is important for ensuring optimal management of those at risk of abnormal visual development. Visual acuity is the aspect of visual function most commonly assessed by optometrists and can be measured in infants and children using appropriate techniques. Acuity measurements obtained using different techniques may show considerable disagreement and may mislead the optometrist when monitoring acuity development. It is important for the practitioner to appreciate these differences so that reasonable comparisons may be made between acuity estimates made using different techniques. With this in mind, we discuss methodological differences between some of the techniques used in visual assessment of very young patients and the effects those differences may have on acuity estimates.

Journal Article↗

PubMed2006

Visual acuity after acute primary angle closure and considerations for primary lens extraction.

BACKGROUND/AIM: Primary lens extraction has been advocated for acute primary angle closure (APAC), but it is not known if this is warranted in all cases. The aim of this study was to investigate the visual acuity (VA) of APAC eyes shortly after resolution of the acute episode in order to assess the appropriateness of performing such surgery in this condition. METHODS: This was a prospective observational case series. As part of a randomised controlled trial comparing phacoemulsification and laser iridotomy, 135 consecutive APAC subjects over a 2 year period underwent subjective refraction and measurement of Snellen VA once the acute episode had resolved with reduction of intraocular pressure (IOP) and improved corneal clarity. RESULTS: Subjects were predominantly Chinese (95.6%) and female (79.3%), with a mean age of 63.6 (SD 9.6) years. When assessed 1.7 (2.7) days after presentation, the majority of APAC cases (50.4%) had good VA (6/12 or better), with more than a quarter of cases having VA of 6/7.5 or better. Poor VA was associated with duration of symptoms (p = 0.04, OR = 4.1, 95% CI 1.1 to 15.7) and time taken to resolution of APAC (p = 0.04, OR = 2.2, 95% CI 1.02 to 4.6), but not with sex (p = 0.31), age (p = 0.26), duration from presentation to measurement of visual acuity (p = 0.53), or presenting IOP (p = 0.73). CONCLUSION: Within days after APAC, more than half of APAC affected eyes had good VA (6/12 or better). The role of lens extraction in the management of APAC warrants further debate, especially for eyes with good VA.

Acute Disease↗

PubMed2004

Irregularity of photoreceptor layer after successful macular hole surgery prevents visual acuity improvement.

PURPOSE: To investigate the association between a photoreceptor irregularity and visual acuity (VA) after macular hole (MH) surgery. DESIGN: Prospective observational case series. METHODS: Twenty-four eyes with an idiopathic MH that resolved after vitreous surgery were examined by new optical coherence tomography (OCT 3000). The images were divided into regular photoreceptor, detected as a straight line above the retinal pigment epithelium reflex, and irregular, which cannot be detected by it. RESULTS: Regular images were observed in 12 eyes (80%) and irregular images in 3 eyes (20%) with good VA (>or=0.7). Regular images were seen in 3 eyes (33%) and irregular images in 6 eyes (67%) with poor VA (<0.7). The percentage of regular images in the group with good VA was significantly higher than that in the group with poor VA (P <.05). CONCLUSION: A photoreceptor irregularity after MH surgery may prevent VA improvement.

Aged↗

PubMed1985

Epidemiologic aspects of senile cataract extraction stratified by visual acuity, age, and sex.

A review of records for 221 patients 50 years old and older undergoing first cataract extractions showed that women constituted 64% of this population (142 cases). The men had a mean age of 70.8 years and the women a mean age of 71.8 years. This difference was not significant. Men had a significantly (P less than .05) better mean best corrected visual acuity preoperatively than women (20/100 vs 20/400). In the two younger groups (those aged 50 to 59 years and those aged 60 to 69 years), men also had significantly (P less than .05) better preoperative visual acuities.

Age Factors↗

PubMedDate not supplied

Visual acuity after successful treatment of large macular retinoblastoma.

Recent trends in the treatment of retinoblastoma have favored radiation therapy as opposed to enucleation. A major determining factor in selecting radiation therapy is the possibility of useful posttreatment visual function. While the treatment of nonmacular tumors seems reasonable, little information is available about the posttreatment visual outcome of large posterior pole tumors. We treated 17 patients (20 eyes) with group III-V retinoblastoma and large posterior pole tumors with external beam radiation. Visual acuity after treatment ranged from 5/200 to 20/50. Potential posttreatment visual function was difficult to predict using such pretreatment factors as age at diagnosis, funduscopic appearance, and the number, size, and location of the tumors. Surprising visual function was obtained in some patients with multiple large macular tumors. Follow up ranged from 1 to 8 years. No patient developed metastatic disease; however, four patients required subsequent cataract extraction. This study supports the consideration of radiation therapy as the primary treatment in eyes previously felt to have a poor visual outcome.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Self-motion-induced eye movements: effects on visual acuity and navigation.

Self-motion disturbs the stability of retinal images by inducing optic flow. Objects of interest need to be fixated or tracked, yet these eye movements can infringe on the experienced retinal flow that is important for visual navigation. Separating the components of optic flow caused by an eye movement from those due to self-motion, as well as using optic flow for visual navigation while simultaneously maintaining visual acuity on near targets, represent key challenges for the visual system. Here we summarize recent advances in our understanding of how the visuomotor and vestibulomotor systems function and interact, given the complex task of compensating for instabilities of retinal images, which typically vary as a function of retinal location and differ for each eye.

Adaptation, Physiological↗

PubMedDate not supplied

Low vision rehabilitation: visual acuity measurement in the low vision range.

1. To predict function and prescribe low vision aids, accurate measurements are needed. The routine measurement range can be extended by moving test charts normally used at 20 ft to a closer distance; 1 m is recommended, which gains a factor of 6. 2. Some practitioners recommend testing all reading at a standard distance, but they differ in the distances they recommend. Using a variable distance and recording the distance with every measurement allows for patients' preferred distances. 3. If the distance and letter size are properly recorded, the same visual acuity score should be calculated for all distances. Inches and J numbers, the most prevalent measurements, make visual acuity calculations impossible, but by adopting metric measurements, calculations are far easier.

Distance Perception↗

PubMed1986

Assessment of visual acuity in infants and children: the acuity card procedure.

The 'acuity card' procedure described here is a simplified method of testing visual acuity of infants and young children, and has been developed to allow preferential looking to be assessed in a laboratory or clinic. A higher proportion of children can be tested successfully than has been reported for more traditional procedures. Initial studies indicate that the acuity card procedure is a fast, accurate method for assessing the acuity of normal infants and children, and those with visual or neurological impairments, across a wide age-range and in both clinical and laboratory settings.

Child Development↗

PubMed1992

Dietary essential fatty acid supply and visual acuity development.

The influence of dietary omega-3 fatty acid supply on visual acuity development was evaluated in very low birth weight (VLBW) infants using visual-evoked potential (VEP) and forced-choice preferential-looking (FPL) procedures at 36 and 57 wk postconception. The VLBW infants born at 27-33 wk postconception were randomized to one of three diet groups: corn oil, which provided solely linoleic acid; soy oil, which provided linoleic and alpha-linolenic acids; or soy/marine oil; which was similar to the soy oil formula but also provided preformed long chain omega-3 fatty acids. The VLBW infants in the soy/marine oil group had higher omega-3 levels in erythrocyte membranes and better VEP and FPL acuities at 36 and 57 wk than infants in the corn oil group. The soy oil group had intermediate omega-3 levels in erythrocyte membranes and significantly poorer VEP acuity at 57 wk compared with the soy/marine oil group. Only the soy/marine oil group had acuities comparable to the "gold standards" of VLBW infants fed human milk and preterm infants who were born and tested at 35-36 wk postconception. In addition, VEP and FPL acuity were poorer in a nonrandomized group of formula-fed full-term infants than in breast-fed full-term infants. The results suggest that dietary omega-3 fatty acid supply may play an important role in early human visual development.

Breast Feeding↗

PubMed1998

Setting an uncorrected visual acuity standard for police officer applicants.

Government agencies have used uncorrected visual acuity (UVA) standards for many years for police officer applicants. With the passage of the Americans With Disabilities Act of 1990, public employers have concern about the validity of these standards. This report shows how data can be used to set a reasonable standard. The report includes a description of a survey of incumbents, acuity testing of a sample of incumbents, collection of essential task information, and experimentation based on the essential tasks. A series of focus group meetings resulted in agreement that 2 essential tasks officers must be able to perform when visually incapacitated are identifying a weapon in a typical room and finding spectacles that have been dislodged. The experimentation showed that a noticeable performance decrement begins to appear at 20/125 level of acuity. As a result of the research, the City of Columbus, Ohio, changed the UVA standard from 20/40 to 20/125.

Adult↗

PubMed1991

Eye movements, visual acuity and spatial constancy.

How are eye movements related to acuity or to the lack of spatial constancy, oscillopsia (OSOP)? How do subjects with congenital nystagmus (CN) suppress OSOP? Can we apply their strategies to cases of acquired nystagmus? In normals, the maintenance of target foveation with low retinal slip is thought to be necessary for good visual acuity. Retinal slip velocities below 1.67-4 deg/sec have been given as upper bounds for good vision. Subjects with CN do not usually have OSOP and can have good (even normal) visual acuity. CN subjects can maintain target position (SD = 0.21 deg) and low retinal slip velocities (SD = 1.97 deg/sec). Previously, we identified two possible mechanisms for the suppression of OSOP in subjects with CN : 1) efference copy of the CN waveform to negate the effects of the oscillation or 2) the stable vision available during foveation periods. A 48 year-old man with hereditary CN lost consciousness; when he came to, he had troublesome, intermittent OSOP. Recordings revealed a jerk left with extended foveation (JLef) waveform when OSOP was absent (SD of eye position was 0.24 deg and SD of retinal slip velocity was 1.87 deg/sec). However, with the onset of OSOP, his CN waveform abruptly changed to jerk right (JR) and was biased several degrees to the right of the target. Phase-plane analysis revealed that, during the periods of OSOP, the JR waveform did not enter the foveation window defined by the limits, 0 +/- 0.5 deg and 0 +/- 4.0 deg/sec.(ABSTRACT TRUNCATED AT 250 WORDS)

Eye Movements↗

PubMed1997

Glare sensitivity and visual acuity after excimer laser photorefractive keratectomy for myopia.

BACKGROUND: Following excimer laser photorefractive keratectomy (PRK), an increase in glare sensitivity and a reduction in contrast sensitivity can occur owing to changes in the cornea (structure and topography). In this study, an attempt was made to quantify and document objectively a change in those subjective perceptual factors. METHODS: Snellen visual acuity and disability glare were measured with the Berkeley glare test preoperatively as well as 1, 3, 6, 9, and 12 months postoperatively, after excimer laser photorefractive keratectomy (PRK) on 32 myopic patients (46 eyes). During the postoperative progress checks, haze was graded and contrast sensitivity was measured with the Vistech chart. All the data were statistically analysed by multiple regression. RESULTS: One year after PRK, a reduction in visual acuity (VA) measured with the low acuity contrast chart (10%) with and without glare could still be found, despite the fact that acuity measurements with a high contrast Snellen chart showed the same VA 6 months postoperatively as well as before the treatment. The lowest VA could be measured 1 month postoperatively; thereafter, the acuity increased despite the increase in haze that occurred during the first 3 months. CONCLUSION: Disability glare and a reduction in contrast sensitivity could be observed in most patients after PRK treatment with the Meditec laser system with its scanning slit. The future will show if new technology and a broader flattening area of 6 to 7 mm can minimise these postoperative complications.

Adult↗

PubMed1990

Intraocular lens implantation after penetrating keratoplasty. Improved unaided visual acuity, astigmatism, and safety in patients with combined corneal disease and cataract.

Twenty-two eyes with combined corneal disease and cataract were followed prospectively after nonsimultaneous intraocular lens (IOL) placement after penetrating keratoplasty; the majority had a penetrating keratoplasty and planned extracapsular cataract extraction (ECCE) followed later by the placement of an IOL. The mean follow-up after IOL placement was 25 months (range, 3-55 months). No graft failures occurred after secondary surgery. All graft sutures were removed in 86% (19/22) of eyes before IOL surgery. Ninety-five percent (21/22) of the eyes achieved refractive errors within 2 diopters (D) of the desired result. Corneal astigmatism decreased from 4.88 to 2.92 D after secondary surgery and wound revision. Unaided visual acuity was 20/40 or better in 68% (15/22) and 20/100 or better in 91% (20/22) of the eyes. The advantages of excellent unaided visual acuity, reduced astigmatism, and lack of anisometropia and graft failure outweigh the disadvantage of some delay in final visual rehabilitation (11 months) and increased secondary capsulotomy rate (85%) in this series with two separate surgeries compared with previously reported triple procedure results.

Adult↗