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Ophthalmic & Physiological Optics : the... Jul 2022To simulate both lens-induced and screen-induced aniseikonia, and to assess its influence on stereopsis. Additionally, to determine if screen-based size differences...
PURPOSE
To simulate both lens-induced and screen-induced aniseikonia, and to assess its influence on stereopsis. Additionally, to determine if screen-based size differences could neutralise the effects of lens-induced aniseikonia.
METHOD
A four-circle (4-C) paradigm was developed, where one circle appears in front or behind the others because of crossed or uncrossed disparity. This stereotest was used for three investigations: (1) Comparison with the McGill modified random dot stereogram (RDS), with anisometropia introduced with +2 D spheres and cylinders, and with aniseikonia introduced with 6% overall and 6% meridional (×180, ×90) magnifiers before the right eye; (2) Comparison of lens-induced and screen-induced 6% overall and meridional magnifications and (3) Determining if lens and screen effects neutralised, by opposing 6% lens-induced magnification to the right eye with screen-inducements of either 6% left eye magnification or 6% right eye minification. A pilot study of the effect of masking versus not masking the surround was also conducted.
RESULTS
The 4-C test gave higher stereo-thresholds than the RDS test by 0.5 ± 0.2 log units across both anisometropic and aniseikonic conditions. However, variations in power, meridian and magnification affected the two tests similarly. The pilot study indicated that surround masking improved neutralisation of screen and lens effects. With masking, lens-induced and screen-induced magnifications increased stereo-thresholds similarly. With lens and screen effects opposed, for most participants stereo-thresholds returned to baseline for overall and ×180 magnifications, but not for ×90 magnification. Only three of seven participants showed good compensation for ×90 magnification.
CONCLUSIONS
Effects of lens-induced aniseikonia on stereopsis cannot always be successfully simulated with a screen-based method. The ability to neutralise refractive aniseikonia using a computer-based method, which is the basis of digital clinical measurement, was reasonably successful for overall and ×180 meridional aniseikonia, but not very successful for ×90 aniseikonia.
Topics: Aniseikonia; Depth Perception; Eyeglasses; Humans; Pilot Projects; Refraction, Ocular
PubMed: 35253250
DOI: 10.1111/opo.12973 -
Indian Journal of Ophthalmology Dec 2022To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia.
PURPOSE
To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia.
METHODS
A cross-sectional study was conducted on 1403 subjects (range: 5-45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets.
RESULTS
There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia.
CONCLUSION
The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.
Topics: Female; Male; Humans; Anisometropia; Emmetropia; Hyperopia; Astigmatism; Cross-Sectional Studies; Amblyopia; Myopia
PubMed: 36453354
DOI: 10.4103/ijo.IJO_658_22 -
Oman Journal of Ophthalmology 2022The purpose of this study was to determine the magnitude and determinants of refractive error (RE) and related ocular morbidities among preparatory and secondary Saudi...
PURPOSE
The purpose of this study was to determine the magnitude and determinants of refractive error (RE) and related ocular morbidities among preparatory and secondary Saudi students in Riyadh.
METHODS
This study was conducted in 2017-2018 at preparatory (12-14 years) and secondary (15-18 years) schools. A "Spot Screener" was used to determine if the child passed or failed a refraction test. Fail test meant RE ≥ ± 0.50 D. Data were collected on refractive status in each eye, anisometropia, and strabismus. The type of RE was estimated and analysis was performed for an association to gender, age, and education levels. The use of spectacle while screening defined the compliance of spectacle wear.
RESULTS
The study sample was comprised of 708 Saudi students. There were 59.5% of boys. The prevalence of RE was 43.6% (95% confidence interval [CI]: 40.0, 47.3). The prevalence of RE in preparatory and secondary students was 44.5% and 43.2%, respectively. The proportion of myopia (≥ -0.5 D) and hyperopia (≥ +0.5 D) among students with RE was 82.2% and 17.8%, respectively. Family history of RE was positively associated to RE in students (odds ratio: 1.8 [95% CI: 1.3, 2.5]). The current screening initiative identified 45 (6.4%) new cases of RE who required spectacles. The compliance rate for using visual aid among students with RE was 74.6%. The prevalence of anisometropia and strabismus was 3.0% and 4.1%, respectively.
CONCLUSIONS
A high proportion of Saudi adolescence in Riyadh have RE. Periodic ophthalmic assessment and refractive services are recommended as part of school health screening initiatives.
PubMed: 35388239
DOI: 10.4103/ojo.ojo_114_21 -
Journal of Current Ophthalmology 2020To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with...
PURPOSE
To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran.
METHODS
In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants.
RESULTS
The prevalence and 95% confidence interval (CI) of presenting visual impairment and blindness was 2.19% (1.48-3.23) and 0.27% (0.12-0.62), respectively. Refractive errors comprised 75% of the causes of visual impairment. The prevalence (95% CI) of myopia [spherical equivalent (SE) ≤ -0.5 D], hyperopia (SE ≥ 0.5 D), and astigmatism (cylinder power < -0.5 D) was 42.71% (39.71-45.77), 3.75% (2.85-4.51), and 29.46% (27.50-31.50), respectively. Totally, 49.03% (46.39-51.68) of the participants had at least one type of refractive error. There was a positive association between weight and myopia (1.01; 95% CI: 1.01-1.02), anisometropia (1.03; 95% CI: 1.01-1.06), and refractive errors (1.01; 95% CI: 1.01-1.02). In comparison with the age group 18-19 years, the odds ratio (OR) of astigmatism in the age group 26-27 years was 1.64 (95% CI: 1.03-2.61), and the OR of anisometropia in the age group ≥ 30 years was 0.21 (95% CI: 0.04-0.98).
CONCLUSIONS
The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders.
PubMed: 32510017
DOI: 10.1016/j.joco.2018.08.001 -
PloS One 2022To analyze ocular biometric changes following unilateral cataract surgery in children.
PURPOSE
To analyze ocular biometric changes following unilateral cataract surgery in children.
METHODS
A total of 57 children aged under 13 years who underwent unilateral cataract surgery were analyzed. Groups were classified according to their age at surgery: group I (age <3), II (3≤ age <6), III (6≤ age <9), and IV (age ≥9). The myopic shift, axial growth, and corneal curvature changes were compared between the pseudophakic eyes and the fellow phakic eyes.
RESULTS
During 7.81 ± 4.39 years, the overall myopic shift (D) and the rate of myopic shift (D/year) were significantly higher at -3.25 ± 3.21 D and -0.45 ± 0.44 D/year in the pseudophakic eyes than -1.78 ± 2.10 D and -0.22 ± 0.29 D/year in the fellow phakic eyes (P = 0.01, 0.004). Group I (-1.14 ± 0.66 vs -0.02 ± 0.45 D/year) and group II (-0.63 ± 0.37 vs -0.31 ± 0.29 D/year) showed significantly higher rate of myopic shift in the pseudophakic eyes than in the phakic eyes. The rate of myopic shift in the pseudophakic eyes decreased in the older age groups (P = 0.001). There was no significant between-eye difference in the changes in axial length and keratometric values postoperatively.
CONCLUSION
Following unilateral cataract surgery, a significant postoperative myopic shift was noticed in the pseudophakic eyes compared to the fellow phakic eyes in groups under 6 years old. Postoperative myopic shift and the resultant anisometropia should be considered when selecting the optimal power of IOL in young children requiring unilateral cataract surgery.
Topics: Aged; Biometry; Cataract; Cataract Extraction; Child; Child, Preschool; Cornea; Follow-Up Studies; Humans; Lens Implantation, Intraocular; Myopia; Refraction, Ocular
PubMed: 35930578
DOI: 10.1371/journal.pone.0272369 -
Translational Vision Science &... Apr 2023This study aimed to examine the differences of retinal oxygen saturation between the paired eyes in anisometropia and to further explore the relation between retinal... (Observational Study)
Observational Study
PURPOSE
This study aimed to examine the differences of retinal oxygen saturation between the paired eyes in anisometropia and to further explore the relation between retinal oxygenation and myopia.
METHODS
This was an observational cross-sectional study, with 124 adults with anisometropia included. According to the interocular differences in spherical equivalent (SE), individuals with a difference ≥3.0 D belonged to the ΔSE ≥ 3.0 D group, and those with a difference ≥1.5 D and <3.0 D belonged to the ΔSE <3.0 D group. The ΔSE ≥ 3.0 D group contained 61, and the ΔSE < 3.0 D group contained 64. All were performed examinations of retinal oximetry, SE, axial length (AL), intraocular pressure, central corneal thickness and average keratometry.
RESULTS
The median SE and AL were -5.06 (-7.22 ∼ -3.41) D and 25.54 (24.73 ∼ 26.62) mm in the "ΔSE < 3 D" group and -4.25 (-6.88 ∼ -2.09) D and 25.52 (24.49 ∼ 26.45) mm in the other group. The retinal arterial oxygen saturation (SaO2) was 93.97% ± 1.26% in the less myopic eyes and 93.18% ± 1.53% (P < 0.001) in the more myopic eyes. In multivariate analyses, SE and AL were both significantly associated with the SaO2.
CONCLUSIONS
The SaO2 between anisometropic myopic eyes was different, and it was associated with SE and AL.
TRANSLATIONAL RELEVANCE
This study demonstrates a relationship between myopia and retinal vascular oxygenation through a novel retinal oximeter.
Topics: Humans; Adult; Anisometropia; Cross-Sectional Studies; Oxygen Saturation; Axial Length, Eye; Myopia
PubMed: 37052910
DOI: 10.1167/tvst.12.4.14 -
Using electronic medical record data to establish and monitor the distribution of refractive errors.Journal of Optometry 2022To establish the baseline distribution of refractive errors and associated factors amongst a population that attended primary care optometry clinics.
OBJECTIVE
To establish the baseline distribution of refractive errors and associated factors amongst a population that attended primary care optometry clinics.
DESIGN
Retrospective cross sectional cohort study of electronic medical records (EMR).
METHODS
Electronic medical record data was extracted from forty optometry clinics, representing a mix of urban and rural areas in Ireland. The analysis was confined to demographic and clinical data gathered over a sixty-month period between 2015 and 2019. Distribution rates were calculated using the absolute and relative frequencies of refractive error in the dataset, stratified for age and gender using the following definitions: high myopia ≤ -6.00 D, myopia ≤ -0.50 D, hyperopia ≥ +0.50 D, astigmatism ≤ -0.75 DC and anisometropia ≥ 1.00 D. Visual acuity data was used to explore vision impairment rates in the population. Further analysis was carried out on a gender and age-adjusted subset of the EMR data, to match the proportion of patients in each age grouping to the population distribution in the most recent (2016) Irish census.
RESULTS
153,598 clinic records were eligible for analysis. Refractive errors ranged from -26.00 to +18.50 D. Myopia was present in 32.7%, of which high myopia represented 2.4%, hyperopia in 40.1%, astigmatism in 38.3% and anisometropia in 13.4% of participants. The clinic distribution of hyperopia, astigmatism and anisometropia peaked in older age groups, whilst the myopia burden was highest amongst people in their twenties. A higher proportion of females were myopic, whilst a higher proportion of males were hyperopic and astigmatic. Vision impairment (LogMAR > 0.3) was present in 2.4% of participants. In the gender and age- adjusted distribution model, myopia was the most common refractive state, affecting 38.8% of patients.
CONCLUSION
Although EMR data is not representative of the population as a whole, it is likely to provide a reasonable representation of the distribution of clinically significant (symptomatic) refractive errors. In the absence of any ongoing traditional epidemiological studies of refractive error in Ireland, this study establishes, for the first time, the distribution of refractive errors observed in clinical practice settings. This will serve as a baseline for future temporal trend analysis of the changing pattern of the distribution of refractive error in EMR data. This methodology could be deployed as a useful epidemiological resource in similar settings where primary eyecare coverage for the management of refractive error is well established.
Topics: Male; Female; Humans; Aged; Astigmatism; Hyperopia; Anisometropia; Electronic Health Records; Cross-Sectional Studies; Retrospective Studies; Prevalence; Refractive Errors; Myopia; Age Distribution; Sex Distribution
PubMed: 36220741
DOI: 10.1016/j.optom.2022.09.001 -
Indian Journal of Ophthalmology Mar 2021To quantitatively correlate the loss of stereopsis by induced anisometropia with its effect on tasks that require binocular vision and stereopsis, such as ophthalmic...
PURPOSE
To quantitatively correlate the loss of stereopsis by induced anisometropia with its effect on tasks that require binocular vision and stereopsis, such as ophthalmic surgery in a simulated environment.
METHODS
Thirty-nine ophthalmic residents with best-corrected visual acuity of 20/20 or better OU, with normal binocular vision and stereopsis, were recruited for the study. Anisometropia was induced using spherical and cylindrical trial lenses from +1D to +5D in a trial frame. The residents performed an anterior chamber navigation exercise on the EYESi simulator and the surgical score at baseline and for each level of induced anisometropia was noted. Near stereopsis was assessed by the Randot test and TNO test at baseline and for each level of induced anisometropia.
RESULTS
Stereoacuity on the Randot test and TNO test were 30 (95% CI, 25.9-34.1) and 44.4 (95% CI, 28.5-60.3) arcseconds, respectively which reduced to 65.5 (95% CI, 48.7-82.3) and 75.9 (95% CI, 15.5-136.3) arcseconds at anisometropia of +1D Sph (P < 0.001) and 380 (95% CI, 309.9-450.1) and 1922.1 (95% CI, 1582.5-2261.7) arcseconds for +5D Sph, respectively for the two tests, (P < 0.001). The corresponding surgical score reduced from 93.8 (95% CI, 91.1-96.7) to 87.5 (95% CI, 79.2-95.8, P < 0.001) for 1 DSph and 55.97 (95% CI, 38.3-73.7, P < 0.001) for 5DSph. There was a strong negative correlation between stereopsis scores and surgical task scores (Spearman's rho -0.86, P value <0.001) Similar changes were seen for anisometropia induced with cylindrical powers.
CONCLUSION
Induced anisometropia is associated with a significant diminution in surgical task scores in a simulated environment and this is correlated with the deterioration in stereoacuity. Assessment of stereopsis may be included as a regular part of the screening procedure for ophthalmic trainee residents.
Topics: Anisometropia; Anterior Chamber; Depth Perception; Humans; Vision, Binocular; Visual Acuity
PubMed: 33595474
DOI: 10.4103/ijo.IJO_1540_20 -
Clinical & Experimental Optometry Jan 2020We live in a three-dimensional world and the human eye can focus images from a wide range of distances by adjusting the power of the eye's lens (accommodation).... (Review)
Review
We live in a three-dimensional world and the human eye can focus images from a wide range of distances by adjusting the power of the eye's lens (accommodation). Progressive senescent changes in the lens ultimately lead to a complete loss of this ability by about age 50, which then requires alternative strategies to generate high-quality retinal images for far and close viewing distances. This review paper highlights the biomimetic properties and underlying optical mechanisms of induced anisometropia, small apertures, dynamic lenses, and multi-optic lenses in ameliorating the visual consequences of presbyopia. Specifically, the advantages and consequences of non-liner neural summation leveraged in monovision treatments are reviewed. Additionally, the value of a small pupil is quantified, and the impact of pinhole pupil location and their effects on neural sensitivity are examined. Different strategies of generating multifocal optics are also examined, and specifically the interaction between ocular and contact or intraocular lens aberrations and their effect on resulting image quality are simulated. Interestingly, most of the novel strategies for aiding presbyopic and pseudophakic eyes (for example, monovision, multifocality, pinhole pupils) have emerged naturally via evolution in a range of species.
Topics: Accommodation, Ocular; Anisometropia; Contact Lenses; Eyeglasses; Humans; Optics and Photonics; Presbyopia; Pupil; Visual Acuity
PubMed: 31734940
DOI: 10.1111/cxo.12987 -
Clinical Ophthalmology (Auckland, N.Z.) 2024Uncorrected refractive errors (REs) and amblyopia can lead to visual impairment with deleterious effects on quality of life and academic performance. Early detection and...
PURPOSE
Uncorrected refractive errors (REs) and amblyopia can lead to visual impairment with deleterious effects on quality of life and academic performance. Early detection and treatment by community vision care programs, such as the UCI EyeMobile for Children, can aid in addressing preventable vision loss.
METHODS
A total of 5074 children between the ages of 3 and 10 years were screened at 153 locations, including preschools, head start programs, and elementary schools within Orange County (OC), California (CA). Subsequently, 1024 children presented for comprehensive eye examinations. A retrospective analysis of all examined children was conducted, determining the frequency and severity of REs and amblyopia and the spectacle prescription rate by age. Propensity score matching analysis evaluated the effect of median household income on RE and amblyopia frequency.
RESULTS
Among those who failed initial screening and were subsequently examined, significant rates of REs and amblyopia were detected: myopia (24.4%), hyperopia (35.4%), astigmatism (71.8%), anisometropia (8.9%), amblyopia (7.0%), and amblyopia risk (14.4%). A majority (65.0%) of those examined received prescription spectacles from UCI EyeMobile, with around a third requiring a new or updated prescription. The frequency of REs and amblyopia and the spectacle prescription rate were uniform across OC congressional districts. Myopia and amblyopia risk was positively and negatively associated with household income, respectively.
CONCLUSION
The UCI EyeMobile for Children serves as a vital vision care program, providing free vision screening, comprehensive eye examinations, and spectacles. A significant number of children required examination, and a high frequency of REs and amblyopia were detected in examined children, with subsequent provision of prescription spectacles to most children.
PubMed: 38860118
DOI: 10.2147/OPTH.S460879