Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “refractive error”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,765 records · Page 98Linked to original sources
PubMed1989

Ocular effects of second generation oral hypoglycemic agents.

Second generation oral hypoglycemic agents, such as glyburide and glipizide, are often the treatment of choice in non-insulin dependent diabetes mellitus. These sulfonylureas are more potent osmotic agents than their predecessors and may give rise to crystalline lens changes and refractive error shifts in the absence of blood glucose variation. Such a case is presented, as is a detailed description of the mechanism of action of commonly prescribed oral hypoglycemic agents.

Administration, Oral↗
PubMed2004

Comparison between two hand-held autorefractors: the Sure-Sight and the Retinomax.

PURPOSE: To compare the results of manifest refraction obtained with two different hand-held autorefractors (Sure-Sight, Welch Allyn Co. and Retinomax 1, Nikon Inc.) and with the Topcon RMA 6000 on-table autorefractor in order to estimate any potential bias between these refractometers and to compare the diagnostic performances of these two hand-held autorefractors as screening devices. METHODS: Ninety-eight children were refracted under manifest conditions with the three above-mentioned refractometers and under cycloplegic conditions with the Topcon on-table autorefractor, or by means of retinoscopy. The agreement between the manifest measurements obtained with the three different autorefractors was studied using the method of Bland and Altman. The validity of several thresholds of manifest refractive anomalies as measured with the Sure-Sight and with the Retinomax was estimated by receiver operating characteristic (ROC) curves using cycloplegic measures as reference. results There is a spherical positive bias of 1 D between the Sure-Sight and the Retinomax and better agreement between the Topcon and the Retinomax. The surface area indexes of the ROC curves and the diagnostic performances in term of sensitivity and specificity are better with the Retinomax in cases of hyperopia, astigmatism and anisometropia. For myopia, the Sure-Sight has better performance. CONCLUSIONS: The results suggest that either device may be sufficient for assessing refractive errors in children in a screening setting. However, because of a bias between both refractometers in measuring the sphere, distinctive referral criteria must be chosen for the detection of hyperopia and myopia. The diagnostic performance is slightly in favor of the Retinomax.

Adolescent↗
PubMed1994

[Video refraction measurement in the first year of life].

BACKGROUND: 426 children were examined, using the isotropic photorefraction method (Atkinson et al. 1981). The aim of this study was to analyze whether the frequency of convergent strabismus and/or amblyopia would increase, particularly in cases of high ametropia, and whether the early prescription of spectacles would be beneficial. The preliminary results of this study are presented here. MATERIALS AND METHODS: 426 children aged between 5 and 12 months were examined. Family history, particularly involving strabismus, ametropia and amblyopia, was ascertained and taken into consideration. RESULTS: Spherical refraction: 92% of the children were emmetropic or slightly hyperopic (< or = +2.5 D). 3.4% were hyperopic (> +2.5 D spherical equivalent) and 4.6% were myopic (0.9 > or = -2.0 D). Astigmatism: 85% had no or mild (< or = 1.5 D) astigmatism. Values greater than 3.5 D were rarely seen. Anisometropia: 67% of the children had no side-difference and only 2.4% had anisometropia with values greater than 1.5 D. Family history/orthoptic findings: 2.6% of the examined population had strabismus. In 12.2% of all the cases one or more first degree relatives had strabismus. Hyperopia and strabismus were found more frequently in this latter group, namely hyperopia (> +2.5 D spherical equivalent) in 13.6% and strabismus in 11.5%. CONCLUSIONS: Refractive errors greater than 2.5 D were seldom seen in this study, and yet were more frequently detected in families with a history of strabismus. In our opinion, isotropic photorefraction is a method most suitable to screening these especially high-risk groups.

Amblyopia↗
PubMedDate not supplied

[The adaptation to contact lenses].

The indications of contact lens adaptation in optical purpose are widely large, starting, with refractive errors [correction of vices], unilateral and bilateral aphakia, myopia, anisometropia and astigmatism, together with the use of contact lens in esthetic purpose. We have been presented the adaptation techniques, the supervise, and maintenance of contact lens.

Adaptation, Physiological↗
PubMed2005

Delayed mfERG responses in myopia.

It has been suggested that changes in the multifocal electroretinogram (mfERG) responses in myopes are primarily due to the increased axial length that accompanies myopia development. We investigated the characteristics of mfERG responses between emmetropes and myopes and determined the contribution of axial length to the mfERG data in 30 subjects (10 emmetropes and 20 myopes) using VERIS I. The amplitude and implicit time of the first positive peak (P1) of the first-order kernel were analyzed. We found that P1 implicit time in myopes was significantly longer by 1.3-3.1 ms than that of the emmetropes and this was not explained by the myopes having greater axial lengths than the emmetropes. Axial length contributed to 15% of the implicit time total variance while refractive error accounted for 27%. Delayed mfERG responses observed in myopes were not attributable to the anatomical change that accompanies myopia and may suggest underlying differences in retinal function that result from being myopic.

Adolescent↗
PubMedDate not supplied

Intraoperative biometry for intraocular lens (IOL) power calculation at silicone oil removal.

PURPOSE: Cataract development is common following retinal detachment surgery that necessitates silicone oil injection. Intraocular lens (IOL) power calculation in the presence of silicone oil is challenging for many reasons. The authors evaluated the accuracy of intraoperative biometry during cataract surgery in silicone-filled eyes. METHODS: Twelve cases of cataract in eyes filled with silicone oil after retinal detachment surgery were included. Preoperatively, keratometric readings were documented. Intraoperative axial length was measured following removal of silicone oil using a sterile probe of the Nidek Echoscan US800 unit. IOL power calculation was computed using the SRK/T formula. This was followed by phacoemulsification and foldable lens implantation. Postoperative refraction allowed evaluation of the accuracy of intraoperative biometry. The predictability of three different formulas was also compared (Holladay, SRK/T, and SRK II). RESULTS: Seven men and five women with a mean age of 50.2 years were included in the study. The mean postoperative spherical equivalent using the described technique was 6.77 +/- 0.43 diopters. SRK/T and Holladay formula had the best predictability for high axial length eyes, whereas the three studied formulas showed no significant differences in predictability in eyes with normal axial length. CONCLUSIONS: Intraoperative biometry proved to have good predictability for the absolute postoperative refractive error in cataract surgery for eyes at the time of silicone oil removal. This predictability was accurate independent of axial length.

Adult↗
PubMed2004

Wavefront corrections of intraocular lenses.

This article describes two currently available intraocular lenses (IOLs) that have special design features allowing for correction of optical aberrations other than spherical refractive errors. Although they are not yet fully "customized" lenses, their development has involved average aberrations measured with wavefront technology. An experimental IOL manufactured with a special technology is also described that, when used in conjunction with wavefront sensing, has the potential for full customization.

Animals↗
PubMed1992

The effect of defocusing the image on the perception of the temporal order of flashing lights.

The temporal interval between flashing lights that is required to perceive nonsimultaneity decreases as the refractive error increases from 0 to +2 diopters. The interval then remains constant with further increases to 3 and 4 diopters. The results are discussed in terms of the relative increase of transient to sustained visual channels and of the increase in apparent movement.

Adult↗
PubMed1986

Performance of the dot visual acuity test with uncorrected ametropia resulting in target blur.

The dot visual acuity test is used to test the acuity of children between the ages of 2 and 4 years who do not respond to the tumbling E test. Because the test involves the detection of a black dot on a white background it is appropriate to ask if the detection threshold is lowered artificially in the presence of target blur. Twenty-one children (42 eyes) were used in the study. Refractive errors were fully corrected and each subject's lag of accommodation was measured. A monotonic decrease in acuity was found with increasing amounts of optical blur. The explanation for the decreased acuity is found in the reduced retinal image contrast of the blurred target.

Accommodation, Ocular↗
PubMedDate not supplied

Visual loss in patients with craniofacial synostosis.

We reviewed the ocular findings in patients with cranial stenosis, who were seen in the Craniofacial Clinic at The Children's Hospital of Philadelphia, to determine the prevalence, pattern, and etiology of visual loss. There were 15 patients with Apert syndrome, 25 patients with Crouzon syndrome, and 18 patients with other forms of craniofacial synostoses. Visual loss occurred in 17 eyes of 11 patients with Apert syndrome, 14 eyes of 11 patients with Crouzon syndrome, and 12 eyes of 8 patients with other craniofacial synostosis syndromes. Refractive errors and strabismus were present in the majority of these patients. Amblyopia due to strabismus, ametropia, or ptosis was the major reason for visual loss in all three groups of patients. Structural abnormalities contributed to loss of vision in six eyes.

Craniofacial Dysostosis↗
PubMed2003

Eccentric correction for off-axis vision in central visual field loss.

BACKGROUND: Subjects with absolute central visual field loss use eccentric fixation and magnifying devices to utilize their residual vision. This preliminary study investigated the importance of an accurate eccentric correction of off-axis refractive errors to optimize the residual visual function for these subjects. METHODS: Photorefraction using the PowerRefractor instrument was used to evaluate the ametropia in eccentric fixation angles. Methods were adapted for measuring visual acuity outside the macula using filtered optotypes from high-pass resolution perimetry. Optical corrections were implemented, and the visual function of subjects with central visual field loss was measured with and without eccentric correction. RESULTS: Of the seven cases reported, five experienced an improvement in visual function in their preferred retinal locus with eccentric refraction. CONCLUSIONS: The main result was that optical correction for better image quality on the peripheral retina is important for the vision of subjects with central visual field loss, objectively as well as subjectively.

Adolescent↗
PubMedDate not supplied

[Changes in the visual system in low birth weight children].

PURPOSE: Evaluation of the visual system, especially refraction, in children with low birth weight under observation between 1990-1992. MATERIAL AND METHODS: 248 children with birth weight 600-2500 g and gestational age 26-37 weeks underwent ophthalmological examination including USG, ERG and VER. The children were first examined between 3-4 weeks of life, then at 8 and 12 weeks and 6, 12, 18 and 24 months. RESULTS: Refractive errors were found in 216 of patients, in 85.2% hypermetropia. ROP occurred in 7 children with birth weight below 1500 g and gestational age 27-32 weeks. Other ocular changes were observed in 19 (7.6%) of the examined children.

Female↗
PubMed1978

Evaluation of 225 consecutive intraocular-lens implants.

A retrospective study of the first 225 intraocular lens implants (IOL) performed by a single surgeon was conducted for this report. In complication rate and visual acuity assessed 4.5 months postoperatively, these patients (pseudophakes) compared very closely with 2 populations of aphakic patients who had had phacoemulsification surgery without lens implantation by the same surgeon. The majority of pseudophakes were left with moderate to low refractive errors. Patient satisfaction was found to be high. It appears that implantation of iris and capsular fixated intraocular lenses is a comparatively safe and in many cases advantageous procedure.

Adult↗
PubMed1982

Development of visual line acuity in humans.

An acuity test was developed with defined space between symbols to determine the effect of crowding on visual line acuity. The test differentiates between normalsighted subjects, those with low but uncorrected refractive errors and amblyopes. Furthermore, the test allows a quantitative examination of the crowding phenomenon and a measure of progress during amblyopia therapy. In normal-sighted subjects a maturational effect on visual line acuity was found, reaching the maximum test level at approximately the tenth year of life.

Age Factors↗
PubMed1987

A survey of visual defects on Tristan da Cunha, 1984.

This paper gives data, obtained during 1984, on the incidence of refractive error and ocular disease in the small, isolated island community of Tristan da Cunha in the South Atlantic. In general, despite inevitable consanguinity among the population of less than 300, ocular health is good.

Adolescent↗
PubMedDate not supplied

Amblyopia: etiology, diagnosis, and treatment. American Academy of Ophthalmology.

1. Sometimes called "lazy eye," amblyopia is poor vision in an eye that did not develop normal sight during early childhood. Amblyopia is common, affecting approximately 2 or 3 out of every 100 people. The best time to correct amblyopia is during infancy or early childhood. 2. Amblyopia has three major causes: strabismus (misaligned eyes), unequal focus (refractive error), and cloudiness in the normally clear eye tissues. 3. To correct amblyopia, a child must be made to use the weak eye. This is usually done by patching or covering the strong eye. Amblyopia cannot be cured by treating the cause alone; the weaker eye must be made stronger in order to see normally.

Amblyopia↗
PubMed2005

Anisometropia is independently associated with both spherical and cylindrical ametropia.

PURPOSE: To explore the associations between anisometropia and spherical ametropia, astigmatism, age, and sex. METHOD: Associations between the prevalence and magnitude of anisometropia with age, sex, spherical power, and cylindrical power, were assessed in a group of 90,884 subjects attending optometry practices in the United Kingdom. Logistic regression models were used to assess the independent contribution of each explanatory variable. RESULTS: Logistic regression analyses that included all subjects or just those aged 20 to 40 years showed that spherical ametropia and astigmatism were independently associated with anisometropia (myopes, P < 1.0E-61; hyperopes, P < 1.0E-11). Anisometropia was relatively stable between the ages of 20 and 40 years, but then became more common with age, in myopes from the age of 40 years onward (P < 0.003) and in hyperopes from the age of 70 years onward (P < 1.0E-6). Sex was not associated with anisometropia to a clinically significant extent. CONCLUSIONS: This is the first study to show an independent association between anisometropia and both spherical ametropia and astigmatism. The results also suggest that the previously noted increased prevalence of anisometropia with age occurs later in hyperopes than in myopes, once other covariates have been controlled for. However, it could not be ruled out that this latter effect was due to clinical selection bias in our sample. The findings suggest that research projects involving the recruitment of highly ametropic subjects, such as those investigating the genetics of refractive error, may benefit by avoiding the use of stringent inclusion criteria for anisometropia, because otherwise a large proportion of the relevant population will be excluded.

Adolescent↗
PubMed1995

Ocular outcome in children born before 32 weeks gestation.

Ocular outcome was assessed in a 2 year cohort of all children born before 32 weeks gestation within a geographically defined population of approximately 3 million. Five hundred and sixty-five children were born within the study period; 558 children (98.8% of the study group) were assessed at approximately 2 years old. There was a high incidence of abnormalities, particularly strabismus (70, 12.5%), cortical visual loss (7, 1.3%), sequelae of retinopathy of prematurity (16, 2.9%) and other significant refractive errors (69, 12.7%). These data provide a recent estimate of gestational age-specific prognosis and suggest that follow-up yields a significant proportion of children with visual abnormalities who could benefit from treatment.

Child, Preschool↗