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Biomedical subjects

D A Goss

Publications and source records attributed to D A Goss.

At least 19 recordsLinked to original sources
PubMed2001

Reliability of rotary prism fusional vergence ranges.

BACKGROUND: The measurement of fusional vergence ranges is an important clinical test in the assessment of binocular vision status. Fusional vergence ranges are typically measured by recording a patient's reports of blur, break, and recovery to base-in (BI) and base-out (BO) prism. Published reliability data on fusional vergence ranges are very limited. METHODS: Eight subjects underwent four testing sessions, at which repeated measurements of fusional vergence ranges were taken. Near ranges were tested at the first session only Distance ranges were tested at all four sessions. Intra-examiner standard deviations were calculated for each fusional vergence test result (BI and BO; blur, break, and recovery) for each session. Intra-examiner standard deviations were averaged. These values were used to determine 95% limits of agreement. RESULTS: The 95% limits of agreement were between 2 delta and 2.5 delta for the distance BI break and recovery and for the near BI recovery; between 3 and 4 delta for near BI break and near BO break; between 4 and 5 delta for distance BO blur and recovery and for near BI blur; and between 5 and 5.5 delta for distance BO break and near BO blur and recovery.

Adult↗
PubMed2000

Nearwork and myopia.

Explore the source record for details and available documents.

Accommodation, Ocular↗
PubMed1999

Refractive error changes in mixed astigmatism.

The purpose of this note is to examine refractive error changes in children who change from mixed astigmatism to myopic astigmatism. Data were collected for 16 children who changed from mixed astigmatism to simple myopic or compound myopic astigmatism. Children with mixed astigmatism showed minimal refractive changes until they converted to myopic astigmatism, at which time refractive changes increased.

Adolescent↗
PubMed1999

Clinical findings before the onset of myopia in youth: 5. Intraocular pressure.

BACKGROUND: We conducted a study to compare variables in children who were initially emmetropic and subsequently became myopic to those in children who remained emmetropic. This paper investigates intraocular pressure (IOP) in the two groups. Some theories of myopia development suggest a role for elevated IOP in axial elongation of the eye, and some studies have found higher IOPs in myopes than in nonmyopes. METHODS: A cohort of initially emmetropic children were given eye and vision examinations at 6-month intervals over a 3-year period. IOPs were obtained by Goldmann tonometry. RESULTS: The mean IOP for the became-myopic group was 13.9 mm Hg (N = 24; SD = 2.5). The mean IOP for the remained-emmetropic group was 14.7 mm Hg (N = 53; SD = 3.1). The difference was not statistically significant. CONCLUSION: Children who became myopic did not show a greater IOP at an examination 6 months or less before the onset of myopia than children who remained emmetropic.

Adolescent↗
PubMed1999

Relationship of accommodative response and nearpoint phoria in a sample of myopic children.

Esophoria has been associated with onset and progression of myopia in children. The induction of myopia by optical defocus shown by animal models suggests that a high lag of accommodation during near work may contribute to myopia in children. This paper examines the relationship of nearpoint phoria and accommodative response in a sample of children with myopia. Accommodative response was measured under binocular conditions with the Canon Autoref R-1 autorefractor with a 40 cm viewing distance. Phorias were measured with the von Graefe method using a 40 cm test distance. In the statistical analysis exophoria was scored as a negative number and esophoria was scored as a positive number. The coefficient of correlation of accommodative response with phoria was -0.32 (n = 73; p<0.01), thus showing an association of a more positive (more convergent) near phoria with lower accommodative response. The correlation coefficient increased to -0.39 when an exponential function was used. When only esophores were considered, the correlation coefficient was -0.59 (n = 44; p<0.001). Lower accommodative response (higher lag of accommodation) was associated with greater esophoria.

Accommodation, Ocular↗
PubMed1999

Nearpoint phoria changes associated with the cessation of childhood myopia progression.

BACKGROUND: A convergent (eso) shift in near phoria associated with the onset of myopia has been reported. METHODS: Data from two Midwestern United States optometry practices were used to assess whether the near phoria shifted back in the divergent (exo) direction after the cessation of childhood myopia progression. Data were collected for myopic children who had three or more examinations before the age of 15 years and at least one examination after the age of 17 years. RESULTS: Refractive error data were used to calculate an index of the age of cessation of childhood myopia progression. The phoria at the first examination after the cessation age was designated as the baseline and was normalized to zero. For all previous and subsequent examinations, the changes in phoria with respect to the baseline phoria were calculated. The phoria at the examination just after the cessation age was significantly more divergent than those at the first, third, and fourth examinations prior to the cessation age (1.1, 1.4, and 1.7 prism diopters, respectively). The third visit after the cessation age was 1.8 prism diopters more divergent than the first visit after the cessation age. Thus, these data showed an exo shift in near phoria after the cessation of childhood myopia progression.

Adolescent↗
PubMed1998

Role of the cornea in emmetropia and myopia.

The purpose of this paper is to review the available evidence concerning the role of the cornea in achieving and maintaining emmetropia, as well as its role in the development and progression of myopia. The role of the cornea in emmetropization is most evident at the two extremes of life. During infancy, when the axial length increases rapidly, both the cornea and the lens become flatter, moving the refractive state of the eye toward emmetropia; during the later years of life, when the axial length remains constant or even shortens, the cornea appears to steepen somewhat. When myopia develops, in some cases the cornea may undergo a "paradoxical" steepening, which accelerates, rather than retards, the development of myopia. The effect of the cornea on the development and progression of myopia is evident when the ratio of axial length to corneal radius--the AL/CR ratio--is considered. Recent studies suggest that a high AL/CR ratio, which has a value of approximately 3.0 in the emmetropic eye, is a risk factor for youth-onset myopia. Several studies have shown that myopic eyes have greater mean corneal powers than emmetropic eyes; this may be mostly due to greater corneal powers being a risk factor for youth-onset myopia.

Accommodation, Ocular↗
PubMed1998

Inter-examiner repeatability of heterophoria tests.

Relatively few studies have reported on the repeatability of heterophoria (phoria) measurement procedures. The purpose of this study was to assess the inter-examiner repeatability of seven clinical tests of phoria measurement, using correlational and mean difference analyses. Two experienced optometrists performed each of the 7 phoria tests on 72 healthy adult subjects. Subjects ranged in age from 22 to 40 years, had visual acuity correctable to 20/20 in each eye, had no strabismus or amblyopia, and had normal eye health. The seven phoria tests used were: (1) the estimated cover test, (2) the prism-neutralized objective cover test, (3) the prism-neutralized cover test with subjective reporting of target movement, (4) the von Graefe phorometry with continuous target presentation, (5) the von Graefe phorometry with flashed target presentation, (6) the Thorington method, and (7) the modified Thorington method. All tests were performed in the same way by both examiners in random sequence, using standard clinical procedures. Inter-examiner correlations were determined for each test, as well as the mean and standard deviation of the differences between each examiner measurement (in prism diopters) on each subject. The modified Thorington method had the smallest mean difference and standard deviation of all tests and, thus, may be considered the most repeatable. This test also had the highest inter-examiner correlation. The prism-neutralized cover test with subjective reporting of target movement had the second highest correlation and the second lowest 95% limits of agreement, but had the largest mean difference of all tests. von Graefe phorometry methods were the least repeatable of the phoria tests.

Adult↗
PubMed1998

Reliability of and comparisons among three variations of the alternating cover test.

One of the most commonly used methods for measuring heterophoria is the alternating cover test. Differences in specific procedures and observational criteria used by examiners may result in different measurements of heterophoria on the same patient. This study evaluated the inter-examiner reliability of three different cover test techniques: the estimated cover test, the prism neutralized objective cover test, and the prism neutralized subjective cover test. Two examiners performed each technique on each of 72 subjects. Reliability was assessed using correlational methods and mean difference calculations. Although there were some inter-examiner differences for the different techniques, all of these differences were within previously determined minimum detectable eye movement ranges. Therefore, when used by experienced clinicians, each of these techniques appears to be a reliable method of heterophoria determination, and their results are comparable.

Adult↗
PubMed1998

Relation of childhood myopia progression rates to time of year.

BACKGROUND: One potential method for assessment of the effect of near work on childhood myopia progression is to compare progression rates overtime spans that have differing near-point demands. METHODS: Myopia progression rates were calculated for a 6-month period during the school year (called school rate in this article) and for a 6-month period that included the 3 months of summer vacation (called summer rate). Data used for analysis were right eye spherical equivalents from manifest subjective refractions of 27 children in a longitudinal study at Northeastern State University in Oklahoma, and 15 children in a longitudinal study at Indiana University. All subjects wore single-vision spectacle lenses. RESULTS: The mean summer rate for the 42 subjects was -0.39 diopters per year (D/yr) (SD = 0.46). The mean school rate was -0.72 D/yr (SD = 0.57). The rates during the two periods were significantly different by two-tailed paired t-test (p = 0.006). CONCLUSIONS: The differing amount of nearpoint activity during the school year and the summer is a potential explanation for the different rates of myopia progression during those two time periods.

Child↗
PubMed1998

Armaignac's 1906 paper on the recording of visual acuity and the progression of letter sizes on visual acuity charts.

BACKGROUND: Henry Armaignac, a French ophthalmologist in the early twentieth century, criticized the Monoyer optometric scale, which was used to measure visual acuity. METHODS: This article discusses the "optometric scale" for visual acuity letter sizes proposed by Armaignac in a 1906 publication. CONCLUSION: Armaignac pointed out the flaws of the Monoyer visual acuity chart commonly used in France at the time and suggested an improvement in the progression of letter sizes on the chart.

Equipment Design↗
PubMed1997

Ocular components measured by keratometry, phakometry, and ultrasonography in emmetropic and myopic optometry students.

Ocular components were measured by keratometry, phakometry, and ultrasonography on 176 young adults. Refractive error was measured by retinoscopy. Mean vitreous depth was greater and the cornea was steeper in myopes than in emmetropes. There were no significant differences between myopes and emmetropes in mean anterior chamber depth, crystalline lens thickness, anterior crystalline lens radius, posterior crystalline lens radius, or crystalline lens power. Coefficients of correlation were calculated for each of the ocular components with refractive error for the entire group of 176 subjects. The components that showed statistically significant correlations with refractive error were vitreous depth and anterior corneal radius. Eyes with greater vitreous depths tended to have flatter anterior corneal surfaces. The slope of the principal axis relating these two variables was significantly different in emmetropes and myopes. Eyes with greater vitreous depths tended to have lesser crystalline lens power. Vitreous depth showed a statistically significant correlation with posterior lens radius, but not with anterior lens radius.

Adolescent↗
PubMed1996

Clinical findings before the onset of myopia in youth: 2. Zone of clear single binocular vision.

BACKGROUND: Many theories of myopia etiology suggest differences in accommodation and convergence in children who become myopic. Several studies have found differences in accommodation and convergence in myopes and emmetropes. Only one previous study examined accommodation and convergence before youth onset myopia. METHODS: A cohort of initially emmetropic children was given eye and vision examinations at 6-month intervals for 3 years. The data collected included fusional vergence ranges at 4 m and 40 cm, and relative accommodation findings with a target at 40 cm. These clinical accommodation and vergence test findings were compared in children who became myopic (became-myopic group) to children who did not (remained-emmetropic group). The mean test findings were used to construct a zone of clear single binocular vision (ZCSBV) for each group. RESULTS: The midpoint between the 40-cm fusional vergence range blur points was more convergent in the became-myopic group (+5.8 delta compared to +3.2 delta in the remained-emmetropic group; p < 0.004). The positive relative accommodation (PRA) finding was less in magnitude in the became-myopic group (-1.46 D) than in the remained-emmetropic group (-2.04 D), the difference being significant at he 0.02 level. CONCLUSIONS: The ZCSBV near blur point were more convergent in the children who became myopic as indicated by the more convergent position of the midpoint of the near fusional vergence range. The lower value for the PRA test in the became-myopic group duplicates the same result reported in a previous study for retrospective longitudinal private practice data.

Accommodation, Ocular↗
PubMed1996

Clinical findings before the onset of myopia in youth: 3. Heterophoria.

BACKGROUND: Some contemporary theories of the etiology of youth onset myopia suggest differences in accommodation and convergence function. Previous studies have related esophoria to various aspects of myopia development. This paper examines whether differences in phorias exist before the onset of myopia. METHODS: A cohort of initially emmetropic children had eye and vision examinations at 6-month intervals for a period of 3 years. Dissociated phorias were measured by the von Graefe method. These prospective data were analyzed by: (1) comparing phorias in children who became myopic to those in children who remained emmetropic; (2) determination of sensitivity and specificity of phorias to distinguish between children who became myopic and those who did not; and (3) determining the change in phorias with time. These same analyses were also performed as additional analyses of some previously published retrospective private practice data. RESULTS: Distance phorias were not significantly different in the became-myopic and remained-emmetropic group by the Mann Whitney U test in either the private practice data or the prospective data. The near phoria was more convergent in the became-myopic group than in the remained-emmetropic group in the private practice data (p < 0.02 by Mann Whitney U test). In the prospective data there were proportionately more children who became myopic outside the near phoria range of 3 delta exo to 1 delta eso (p < 0.05 by chi 2 test). In both data sets the near phoria showed an eso shift with time in the children who became myopic, beginning before and continuing after the onset of myopia. The children in the remained-emmetropic groups did not show eso shifts in near phoria. CONCLUSIONS: A near phoria which is not close to orthophoria appears to be a risk factor for youth onset myopia, but sensitivity and specificity were not as high as those for other variables such as corneal power, axial length to corneal radius ratio, positive relative accommodation (PRA), and midpoint of the near fusional vergence range. The onset of myopia is associated with an eso (convergent) shift in the near phoria.

Child↗
PubMed1996

Clinical findings before the onset of myopia in youth: 4. Parental history of myopia.

BACKGROUND: We conducted a study to compare variables in children who were initially emmetropic and became myopic to those in children who remained emmetropic. This paper examines parental history of myopia in the two groups of children. METHODS: A cohort of initially emmetropic children was given eye and vision examinations at 6-month intervals for 3 years. Data on parental history of myopia were obtained by questionnaire. RESULTS: A greater proportion of children in the became-myopic group had myopic parents compared to children in the remained-emmetropic group. The sensitivity for onset of myopia was 0.95 and specificity was 0.38 if at least one parent was myopic. A sensitivity of 0.36 and a specificity of 0.87 were found for both parents being myopic. There was a significant association between parental history of myopia and development of myopia in the children in the study (p < 0.01 by chi 2 for categorization of whether neither, one, or both parents were myopic for children in the became-myopic and remained-emmetropic groups). CONCLUSION: Parental history of myopia is a risk factor for the development of myopia.

Child↗
PubMed1996

Reliability of and comparisons among methods of measuring dissociated phoria.

Many methods of heterophoria measurement are available clinically. This paper reviews several studies which have examined the reliability of phoria measurements, and have compared various tests of phoria measurement. Different methods of data analysis make comparison of studies difficult. Two studies indicated 95% limits of agreement of 2 to 4 delta for reliability of modified Thorington, von Graefe, and Maddox rod phoria tests. Studies using correlational analysis to compare different measurement methods have found a high degree of association of the results of these methods. Studies using statistical methods assessing the agreement of test results found a high level of agreement among some tests and a low level of agreement among some tests. Some of the various phoria measurement methods differ in the technique used for dissociation, in the ability to control accommodation adequately, in the level of proximal convergence induced, or in the method by which the phoria is quantified. These differences can result in different phoria measurements on the same patient.

Humans↗
PubMed1996

A comparison of three subjective tests for astigmatism and their interexaminer reliabilities.

BACKGROUND: Astigmatism is a common cause of blurred vision and asthenopia. Several different tests for the measurement of astigmatism have been described in the literature, but there are few studies that have compared the results of various tests. METHODS: The results of three astigmatism tests performed on 40 subjects by two examiners were compared. Two of the tests, the Jackson cross cylinder (JCC) and the Humphriss immediate contrast (HIC), utilized distance targets; one test, the Pratt test, involved a near target. RESULTS: The mean differences between all tests were less than 0.25D. There was a slight tendency for higher cylinder power to be found on the Pratt test. The three tests agreed within +/- 0.25D on cylinder power 80 to 98 percent of the time and within 10 degrees of cylinder axis 85 to 98 percent of the time. Interexaminer reliability showed mean differences less than 0.12D for each of the three tests, agreement within +/- 0.25D on cylinder power 88 to 90 percent of the time and within 10 degrees on cylinder axis 85 to 93 percent of the time. CONCLUSIONS: The results suggested that any of the three techniques could be substituted for another for astigmatism testing. On theoretical grounds, a binocular refraction method for cylinder axis determination, such as the HIC, is advisable for patients with cyclophorias and significant amounts of astigmatism. The results showed good reliability for each of the three methods.

Adolescent↗