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Academic literature on the topic 'Eye - Accommodation and refraction - Statistical methods'
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Journal articles on the topic "Eye - Accommodation and refraction - Statistical methods"
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Bolinovska, Sofija, and Jovan Popovic. "Cyclopentolate as a cycloplegic drug in determination of refractive error." Medical review 61, no. 7-8 (2008): 327–32. http://dx.doi.org/10.2298/mpns0808327b.
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Cycloplegia is loss of the power of accommodation with inhibition of a ciliary muscle. We obtain in this way the smallest refraction of the lens and make it possible to determine the presence and size of the particular refractive error in cycloplegia by using cyclopentolate. Cyclopentolate is a synthetic anticholinergic drug and antagonist of the muscarine receptors. If applied in the eye, it blocks the effect of cholinergic stimulation on the sphincter pupillae muscle and ciliary muscle. It provokes severe mydriasis (dilation of the pupil) and cycloplegia (paralysis of the accommodation). Cyclopentolate has been used occasionaly in diagnostic purposes: defining ocular refraction and in ophthalmoscopy. This is the prospective study which included 200 children (400 eyes) aged 3-18 years, carried out in one ambulatory ophthalmological examination. The results were analysed using standard statistical methods. The most often refractive error in the examined group of children is hyperopia with hyperopic astigmatism, then myopia with myopic astigmatism and mixtus astigmatism are the most often in the oldest group of children. The mean value of corneal astigmatism on the right eye was 1.24 D, on the left eye 1.23 D. Anisometropy was found in 40% children. The presence of myopia, myopic and astigmatism mixtus tended to increase, and hyperopia and hyperopic astigmatism tended to decrease toward older groups of children. Refractive error could result in a poor development of visual acuity, causing amblyopia and strabismus, and because of that represents an important public health problem. As one of amblyogenic risk factors in children, it can be prevented with screening program and appropriate treatment, thus providing prevention of amblyopia as one form of blindness.
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Stokkermans, Thomas J., Jeremy C. Reitinger, George Tye, Chiu-Yen Kao, Sangeetha Ragupathy, Huachun A. Wang, and Carol B. Toris. "Accommodative Exercises to Lower Intraocular Pressure." Journal of Ophthalmology 2020 (December 18, 2020): 1–7. http://dx.doi.org/10.1155/2020/6613066.
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Purpose. This study investigated how a conscious change in ocular accommodation affects intraocular pressure (IOP) and ocular biometrics in healthy adult volunteers of different ages. Methods. Thirty-five healthy volunteers without ocular disease or past ocular surgery, and with refractive error between −3.50 and +2.50 diopters, were stratified into 20, 40, and 60 year old (y.o.) age groups. Baseline measurements of central cornea thickness, anterior chamber depth, anterior chamber angle, cornea diameter, pupil size, and ciliary muscle thickness were made by autorefraction and optical coherence tomography (OCT), while IOP was measured by pneumotonometry. Each subject’s right eye focused on a target 40 cm away. Three different tests were performed in random order: (1) 10 minutes of nonaccommodation (gazing at the target through lenses that allowed clear vision without accommodating), (2) 10 minutes of accommodation (addition of a minus 3 diopter lens), and (3) 10 minutes of alternating between accommodation and nonaccommodation (1-minute intervals). IOP was measured immediately after each test. A 20-minute rest period was provided between tests. Data from 31 subjects were included in the study. ANOVA and paired t-tests were used for statistical analyses. Results. Following alternating accommodation, IOP decreased by 0.7 mmHg in the right eye when all age groups were combined ( p = 0.029). Accommodation or nonaccommodation alone did not decrease IOP. Compared to the 20 y.o. group, the 60 y.o. group had a thicker ciliary muscle within 75 μm of the scleral spur, a thinner ciliary muscle at 125–300 μm from the scleral spur, narrower anterior chamber angles, shallower anterior chambers, and smaller pupils during accommodation and nonaccommodation ( p ’s < 0.01). Conclusion. Alternating accommodation, but not constant accommodation, significantly decreased IOP. This effect was not lost with aging despite physical changes to the aging eye. A greater accommodative workload and/or longer test period may improve the effect.
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Jitendra, Yadav, De Tapas Kumar, Sah Sanjay Kumar, and Anyam Sandip Das. "Changes in anterior segment parameters of normal subjects during accommodation using a Scheimpflug imaging system." Medical Hypothesis, Discovery & Innovation in Optometry 1, no. 3 (March 22, 2021): 124–28. http://dx.doi.org/10.51329/mehdioptometry117.
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Background: Accommodation changes ocular parameters, such as the anterior chamber volume (ACV), anterior chamber depth (ACD), anterior chamber angle (ACA), and pupil diameter (PD), which can reflect a risk of angle-closure glaucoma. Previous studies of changes in ocular anterior segment parameters, have used high diopters or maximum amplitude. Here, we focused on normal accommodation at a reading distance of 30‒40 cm. The aim of this study was to assess changes in anterior segment parameters during a normal accommodative state, using a Scheimpflug imaging system.
Methods: In this cross-sectional study, 40 emmetrope subjects (mean ± SD of age: 22 ± 4.0 years) who met the inclusion criteria and provided informed consent were enrolled. Clinical history, refraction, amplitude of accommodation, slit lamp examination, Goldman applanation tonometry, and Pentacam investigations were performed on all subjects. Accommodative and non-accommodative targets were induced via the Pentacam. Two seconds were allowed for accommodation or relaxation prior to measurements in each eye.
Results: Eighty normal eyes were evaluated; a small but statistically significant change in ACV, ACA, and PD during accommodation (P < 0.01, < 0.01, and < 0.05, respectively) was observed. The ACD did not change substantially with accommodation (P = 0.29). The mean ± SD values of ACV, ACD, ACA, and PD before and after accommodation were 151.85 ± 24.04 mm3 and 145.38 ± 23.30 mm3, 2.87 ± 0.28 mm and 2.86 ± 0.27 mm, 35.06° ± 3.68° and 33.84° ± 3.72°, and 3.46 ± 0.57 mm and 3.41 ± 0.53 mm, respectively.
Conclusions: Accommodation changes ocular parameters, such as ACV, ACA, and PD, in healthy young emmetropes. Interestingly, the ACD remains unaltered during accommodation. Nevertheless, although these changes were statistically significant, they were not clinically significant in our study.
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Chaudhary, Neha Priyadarshani, Pramod Sharma Gautam, Sagar Dahal, and Devendra Acharya. "Study of the Amplitude of Accommodation and its Relation to Errors of Refraction: A Hospital Based Study." Journal of Nobel Medical College 7, no. 2 (December 31, 2018): 20–24. http://dx.doi.org/10.3126/jonmc.v7i2.22289.
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Background: The unique ability of the eye to vary the refractive power of the lens and to focus on things at a range of distances is called accommodation. The reduction of this ability in which the near point recedes further away from comfortable reading distance is called presbyopia. There is continuing research to understand this process and correct this affliction that affects each and every person at the peak of their productive life. With an aging population, the proportion of people above 40 years is on the rise. This will therefore have public health and economic implications.
Materials and Methods: This is a hospital based retrospective study which was conducted in 100 presbyopic patients in age group of 35 to 60 years at outpatient department of ophthalmology in Nobel Medical College and Teaching Hospital, Biratnagar, from 1st October 2016 to 30th March 2017. The amplitude of accommodation was calculated by measuring near point of accommodation with the help of RAF rule and the data collected was subjected to statistical analysis.
Results: Out of 100 patients in this study who visited our OPD with presbyopic complains, the no. of hypermetropic patients were highest (56%) and they presented with presbyopic symptoms at an early age as compared to myopes, while the no. of myopic patients were less(13%) and they presented late with presbyopic symptoms. The mean amplitude of accommodation was highest in myopes in all age group (3.35 D in 36-40 year age group which reduced to 2.65 D in 56-60 year age group).There was stastistically significant difference in amplitude of accommodation between myopia and hypermetropia in all age groups except in 56-60 year age group.
Conlusion: The amplitude of accommodation is generally higher in myopes in all age groups as compared to hypermetropes and emmetropes and they usually develope presbyopic symtoms later in life.
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Sergeeva, A. V., O. V. Kolenko, E. L. Sorokin, and Y. E. Pashentsev. "Features of the Development of Eyes and the State of Refraction in Children of the Indigenous Peoples of the North Living in the Amur Region." Russian ophthalmology of children, no. 3 (October 21, 2020): 13–18. http://dx.doi.org/10.25276/2307-6658-2020-3-13-18.
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Purpose. To study the anatomical and morphometric parameters of the eyes and the state of refraction in children of the indigenous and alien population living in the Khabarovsk krai of Russia. Material and methods. The study included 180 children living in the Nanai District of the Khabarovsk krai, aged from 3 months to 18 years. Two groups of children were formed, according to the criteria of belonging to the indigenous/alien population. 1st group – 84 children of the indigenous population – Nanai. 2nd group – 96 children of the alien population - peoples related to the Slavs. Both groups were matched for gender and age. In each of these groups, 5 age subgroups were formed. The comparison group is the average statistical indicators of the child population of Russia in the corresponding subgroups. Results. In comparative study, difference in the refractive index of the cornea was not found between the groups. A statistically significant delayed growth of the axial length of the eye was revealed in children of the indigenous population of the Khabarovsk krai in the age subgroups of 4–6, 7–10, 11–14 years old, in comparison with similar subgroups children of the newcoming population and with the average Russian indicators. Tendency to myopization was revealed in children of the 1st group from 7–10 years and older at retinoscopy on narrow pupil, in whom, after cycloplegia with 0,5–1% solutions of Cyclopentolate, a shift towards hyperopic refraction was revealed. Conclusion. The revealed features of the development of eyes in children of the indigenous population of the Khabarovsk krai must be taken into account, conducting them retinoscopy only in the conditions of achieving complete medical accommodation paresis, and, if necessary, to prescribe them adequate optical correction. This will allow timely prevention of the formation of complications associated with the peculiarities of the development of their refraction.
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Kaluzny, B. J. "Anterior Movement of the Crystalline Lens in the Process of Accommodation in Children." European Journal of Ophthalmology 17, no. 4 (July 2007): 515–20. http://dx.doi.org/10.1177/112067210701700406.
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Purpose To investigate changes of crystalline lens position during accommodation in children with emmetropia, myopia, and hyperopia. Methods A total of 188 children (372 eyes) from 4 to 19 years old (mean age 11.3±4.43) with cycloplegic refractive error within a range +9.00 D to −9.00 D were enrolled. After a general ophthalmic examination, ultrasound biometry was performed, with the eye at a maximal accommodative effort. Cycloplegia was induced by triple installation of 1% tropicamide drops and 30 minutes later the biometric examination was repeated. Results In emmetropic eyes in the process of accommodation, the anterior pole of the crystalline lens moved forward by 0.144±0.14 mm (p ≤ 0.001); the position of the posterior pole did not change. In myopic eyes, the anterior pole moved forward by 0.071±0.13 mm (p≤0.001) and the posterior pole moved backward by 0.039±0.10 mm (p=0.003). In hyperopic eyes, the whole lens translocated anteriorly: anterior pole moved forward by 0.242±0.16 mm (p≤ 0.001) and posterior pole moved forward by 0.036±0.09 mm (p≤0.001). Differences among emmetropia, myopia, and hyperopia were statistically significant. Forward movement of the posterior pole correlated with a low axial length of the eye, and also with plus refractive error and with a smaller accommodative increase of lens thickness. Conclusions In children, accommodative changes of the crystalline lens position depend on refractive status.
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Tarutta, E. P., N. A. Tarasova, G. A. Markosian, S. V. Milash, S. G. Harutyunyan, K. A. Ramazanova, and N. L. Cherednichenko. "Changes in functional, anatomical and optical parameters of the eye in children with habitually excessive accommodation stress and pseudomyopia after regular badminton playing." Russian Ophthalmological Journal 12, no. 4 (December 12, 2019): 51–63. http://dx.doi.org/10.21516/2072-0076-2019-12-4-51-63.
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Purpose. To study the state of refraction, accommodation, and blood flow in eye vessels of children with habitually excessive accommodation stress (HEAS) and pseudomyopia practicing badminton.Material and methods. The study involved 11 patients (20 eyes) aged 7 to 11 years (average M±SD: 9.24 ± 1.06 years) with pseudomyopia and HEAS: 4 patients with myopia (7 eyes), 3 children with hyperopia (6 eyes), 4 children with emmetropia (7 eyes) before they started practicing badminton and after playing it for a certain time. All patients were tested for visual acuity, subjective and objective accommodation, optical biometry, aberrometry, velocity of blood flow in eye vessels, and choroidal thickness.Results. After 1 year of regular badminton workout, the subjects revealed a 0.92 ± 0.82 D weakening of manifest refraction, a decrease in accommodation tone by 0.85 ± 0.77 D, an increase in blood flow rate in ophthalmic artery and the central retinal artery, an increase in positive spherical aberration, a decrease in aberrations associated with mismatch and irregularity ofoptical system elements (tilt, trefoil, coma), which indirectly indicates a strengthening of the ligamentous apparatus of the lens.Conclusion. Practicing sports (badminton) contributes to the elimination of pseudomyopia, improvement of uncorrected visual acuity, accommodative ability, and ophthalmic hemodynamics indicators.
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Tarutta, E. P., N. A. Tarasova, G. A. Markosyan, N. Yu Kushnarevich, and T. Yu Larina. "An objective study of negative accommodation." Russian Ophthalmological Journal 12, no. 1 (March 16, 2019): 64–68. http://dx.doi.org/10.21516/2072-0076-2019-12-1-64-68.
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Purpose: to study the dynamic refraction of myopic eyes at the time when the object is fixed in an open field at a distance of 5 m and determine habitual accommodation tone (HAT) in an open field. Material and methods. 130 patients (260 eyes) aged 6 to 23 years (ave. 11.26 ± 0.2 years) with an average refraction spherical equivalent of -4.16 ± 0.13 D were divided into 4 groups, depending on the degree of myopia. The HAT was measured by an automatic binocular open field (OP) autorefkeratometer Grand Seiko WR-5100K (Japan), while the HAT according to Yuri Rosenblum was determined by a conventional autorefractometer Nidek. Results. Comparing noncycloplegic and cycloplegic refraction using the two devices, we obtained different results. In the first case, we found the maximal difference of -0.15 D (-4.38 – (-4.23)), and in the second case, the minimal difference of -0.09 D (-4.16 – (-4.07)). Over the whole group, HAT according to Yuri Rosenblum averaged -0.21 ± 0.02 D. In patients with low myopia HAT was the highest and averaged -0.33 ± 0.03 D. In patients with moderate myopia an average HAT level was -0.23 ± 0.03, and in high myopia it was -0.19 ± 0.04 D. Patients with anisomyopia showed a significant difference of the tone between the fellow eyes: the eyes with lower refraction showed a HAT of -0.21 ± 0.03 D, while for the worse eye it was 0.06 ± 0,11 D (p < 0.05) (i.e. a negative accommodation tone). Over the whole contingent HAT OP averaged -0.17 ± 0.02 D: in patients with low myopia it averaged -0.22 ± 0.04 D, in those with moderate myopia, -0.27 ± 0.02 D, in high myopia — -0.09 ± 0.04 D. PTA OP patients with anisomyopia averaged -0.07 ± 0.03 D and demonstrated a significant difference between the eyes (-0.26 ± 0.03 D for the better eyes and 0.12±0.06 D — for the worse eyes, p < 0.01). A negative tone of accommodation of HAT OP in myopia occurs, on average, in 30% of patients; the frequency was maximal in high myopia (50 %) and minimal in moderate myopia (13.8 %). Conclusions. Objectively determined the weakening of the far dynamic refraction as compared with the static refraction (in terms of cycloplegia) was objectively determined. Thus, the existence of negative accommodation was confirmed.
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Khvatova, Natalya, and Natalya Slishalova. "Available methods of the examination of accommodation of the eye in the ophthalmological outpatient department (materials from the Conference on Accomodation, Yaroslavl, 2019)." Eye 126, no. 2019-2 (June 2019): 59–68. http://dx.doi.org/10.33791/2222-4408-2019-2-59-68.
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Time limits in the outpatient department practice do not allow to perform an extensive examination of young patients with refraction and accommodation disorders and to assess the severity and significance of their condition. Constantly redundant tension of accommodation (CRTA), weakness of accommodation, as well as the in¬flexibility of accommodation – all have the similar clinical picture, require a careful approach to differential diagnosis and, thereby, different methods of treatment. Therefore, the examination of accommodation of younger patients must be as comfortable as possible, not tedious, impersonal and informative. Accommodation disorders not only accompany, but also act as triggers as far as a number of diseases are concerned, the role of accommodation response delay has been already proven to be a reason of myopia progression. Underestimation of their role in the development of some pathological conditions can leave a patient with¬out the required assistance and limit his or her visual performance during the most productive age. The authors offer an examination algorithm that does not contradict with global requirements on this issue, but significantly reduces the amount of time that doctors need for detecting an accommodation disorder. The relevance of the suggested algorithm of subjective and objective accommodation examination methods is that they do not require expensive equipment, are not time-consuming and are quite accurate despite their apparent simplicity.
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Asakawa, Ken, Susumu Kanno, Tomonori Ando, Kenji Osawa, and Hitoshi Ishikawa. "The Effects of Chewing Gum in Preventing Eyestrain." BioMed Research International 2020 (November 16, 2020): 1–7. http://dx.doi.org/10.1155/2020/2470473.
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Purpose. To investigate the effects of chewing gum and tablet candy to reduce eyestrain in healthy individuals. Materials and Methods. A double-blinded crossover trial was conducted. Forty-six healthy individuals (23 men, 23 women) between 20 and 59 years old, feeling eyestrain, were enrolled. Each 10-year age group included 12 individuals except the 30s group, which included 10 individuals. A visual task was performed on reading material displayed on a computer screen at a fixed distance for 60 min. Gum or tablet candy of two pieces were chewed for two 15-min periods starting 15 and 45 min after starting to read. Subjects chewed gum on Day 1 and tablet candy on Day 2, and vice versa. Primary outcome is as follows: subjective eye fatigue (eye tiredness, eye heaviness, blurred vision, double vision, and eye dryness) using a visual analog scale (VAS). Secondary outcomes are as follows: subjective accommodation from near and far points of accommodation measured with a D’ACOMO, spherical equivalent refraction, and eye dryness by analyzing ring break-up time (RBUT) measured with the RT-7000 Auto Ref-Topographer. Results. The VAS scores of subjective eye fatigue were not significantly changed between chewing gum and tablet candy ( P = 0.397 - P = 0.909 ). Those scores of eye tiredness and eye heaviness were significantly longer before and after the visual task with tablet candy ( P = 0.013 and P = 0.025 , respectively) but not with chewing gum. The changes of subjective accommodation were significantly lower after the visual task between chewing gum and candy ( P = 0.043 ). There were significant differences among each age group (20 s vs. 30 s, P = 0.594 ; 20 s vs. 40 s, P = 0.002 ; 20 s vs. 50 s, P = 0.002 ). After reading, the changes of spherical equivalent refraction did not indicate a shift toward myopia ( P = 0.267 ). In the RBUT, there were no significant differences between the samples ( P = 0.680 ). Conclusions. Chewing gum helps improve the ability of the eye to focus, especially in young adults.
Dissertations / Theses on the topic "Eye - Accommodation and refraction - Statistical methods"
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Cronje-, Dunn Sonja. "Short-term keratometric variation in the human eye." Thesis, 2014. http://hdl.handle.net/10210/9106.
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M.Phil. (Optometry)Previous studies of corneal and keratometric variation used incomplete or incorrect statistical methods. For the first time, proper multivariate statistical methods are applied to evaluate short-term keratometric variation in human eyes. Keratometric variation is represented graphically by means of stereo-pair scatter plots, trajectories of change in dioptric power, ellipsoidal confidence regions for mean dioptric power, as well as meridional profiles. Quantitative expressions of variation are given in terms of mean values, variance-covariance matrices and volumes of 95% distribution ellipsoids. Manual and automatic keratometry is compared, both on a steel ball and on an eye. It appears that the automatic keratometer exhibits less variation than the manual keratometer....
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Klaassen, Donald Gregory Istvan. "Keratometric variation during pregnancy and postpartum." Thesis, 2012. http://hdl.handle.net/10210/6644.
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M.Phil.Keratometric readings on three subjects were taken both during pregnancy and postpartum. One subject was visually non-compensated and did not require refractive correction, one was a contact lens wearer and one had undergone radial keratotomy. Twenty readings were taken by means of an automatic keratometer on each eye, morning and afternoon, every fortnight. The recent matrix method of optometric statistical analysis was employed and the results graphically compared and analysed. Findings indicate diurnal variations including variation in corneal curvature and variance through the course of normal pregnancy. Most evident was an increase in keratometric variation in all three subjects at the time of birth and a substantial decrease in corneal refractive power in the subject who had before undergone radial keratotomy. This result may have far-reaching implications on the long term prognosis of refractive surgery especially for females of child bearing age. Outliers representing transient increases in curvature were most common in the vertical meridian (indicating possible lid interaction), while the presence of bimodal distributions suggests a sensitivity of the automatic keratometer to changes in head posture.
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Malan, Dawid Johannes. "The excess of objective automatic refraction over subjective clinical refraction : methods of analysis and results." Thesis, 2014. http://hdl.handle.net/10210/9753.
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M.Sc. (Optometry)The difference between objective automatic and subjective clinical refraction is studied using new statistical techniques. The question, by how much the two refraction techniques differ, is investigated by subtracting the subjective refraction finding from the auto refractory finding and then examining the distribution of the difference or excess as it will be called here. Computerized procedures were developed to automate mathematical and statistical methods of analysis. The methods were applied to two different samples: one of patients visiting an ordinary optometric practice (the clinical sample) and the other of children refracted in a screening program (the sample of school children) . The clinical sample, consisting of mainly older patients, is examined first. The difference between the autorefractor and subjective findings is studied and described. This difference could be used to compare different types of auto refractors assuming that the subjective refraction is correct. For the purpose of this study, however, the results of eight autorefractors are grouped together, combining left and right eyes, to serve as basis for studying the older population. The study shows that on the average there is no clinically significant excess. This means that there is on average no clinically significant difference between the automatic and clinical refraction for this population.
Books on the topic "Eye - Accommodation and refraction - Statistical methods"
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Lens, Al. Optics, retinoscopy, and refractometry. 2nd ed. Thorofare, NJ: SLACK Inc., 2005.
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Manas, Leo. Visual analysis. 4th ed. Santa Ana, CA: Optometric Extension Program Foundation, 2009.
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Manas, Leo. Visual analysis. 4th ed. Santa Ana, CA: Optometric Extension Program Foundation, 2009.
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The methods employed in examining the eyes for the detectio[n] of hysteria: Presented to the section on neurology and medical jurisprudence at the forty-ninth annual meeting of the American Medical Association held at Denver, Colo., June 7-10, 1898. Chicago: American Medical Association Press, 1985.
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