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Biomedical subjects

D O Mutti

Publications and source records attributed to D O Mutti.

51 records · Page 3Linked to original sources
PubMed1994

The effect of parental history of myopia on children's eye size.

OBJECTIVE: To evaluate whether eye size and shape are different in children based on their parental history of myopia. DESIGN: A community-based cohort study of schoolchildren (aged 6 to 14 years), the Orinda (Calif) Longitudinal Study of Myopia. SETTING: Four campuses of the Orinda Union School District, a predominantly white, high socioeconomic status community. PARTICIPANTS: A cross-sectional volunteer sample of 716 children (662 non-myopic) in the first, third, and sixth grades in 1989, 1990, and 1991. All children in those grades were eligible for inclusion in the study. INTERVENTION(S): None. MAIN OUTCOME MEASURES: Refractive error (measured by autorefraction), corneal curvature (measured by photokeratoscopy), crystalline lens power (measured by video phakometry), and axial ocular dimensions (measured by ultrasonography). RESULTS: With prevalent cases of myopia excluded and grade in school and "near work" controlled for, children with two myopic parents had longer eyes and less hyperopic refractive error (analysis of covariance, P < or = .01) than children with only one myopic parent or no myopic parents. A model incorporating parental history is only improved by the addition of near work for the prediction of refractive error. CONCLUSIONS: Even before the onset of juvenile myopia, children of myopic parents have longer eyes. These results suggest that the premyopic eye in children with a family history of myopia already resembles the elongated eye present in myopia.

Adolescent↗
PubMed1994

The effect of cycloplegia on measurement of the ocular components.

PURPOSE: The purpose of this study was to examine the effect of cycloplegic agent on the measurement of refractive error and the ocular components. METHODS: We compared two commonly used topical cycloplegic agents, 1% tropicamide and 1% cyclopentolate, for their effect on the measurement of refractive error (by Canon R-1 autorefraction), accommodative response (by Canon R-1 autorefraction and by the conventional, subjective "pushup" method), crystalline lens power (by video phakometry and by calculation), and axial ocular dimensions (by A-scan ultrasonography) in 20 emmetropic to moderately hyperopic children. RESULTS: Comparison of refractive error at each drug's reported time of maximum cycloplegia (30 minutes for tropicamide and 60 minutes for cyclopentolate) showed that distance autorefraction in the vertical meridian differed by +0.20 +/- 0.30 diopters (D) (P = 0.008). The average difference was +0.07 +/- 0.10 mm for anterior chamber depth (P = 0.004), -0.03 +/- 0.05 mm for crystalline lens thickness (P = 0.025), -0.65 +/- 0.69 D for phakometrically measured crystalline lens power (P < 0.001), +0.03 +/- 1.55 D for calculated crystalline lens power (P = 0.94), and -0.09 +/- 0.19 mm for vitreous chamber depth (P = 0.062, all paired t tests; positive signs denote greater values with cyclopentolate). Residual accommodation was 0.47 and 0.67 D greater with tropicamide when measured by autorefraction and the pushup method (P = 0.013 and 0.08 respectively, paired t test). All significant differences were consistently in the direction of poorer cycloplegia with tropicamide. CONCLUSIONS: Although tropicamide, as expected, showed poorer cycloplegia compared to cyclopentolate, the degree of difference appeared to be small, with minimal effect on the measurement of distance refractive error and the ocular optical components.

Accommodation, Ocular↗
PubMed1993

Initial cross-sectional results from the Orinda Longitudinal Study of Myopia.

BACKGROUND: Although investigations of human refractive error development and normal ocular growth have been conducted for the last 50 years, no previous study of refractive error and the ocular components has measured all the ocular components. METHODS: The Orinda Longitudinal Study of Myopia was initiated to characterize the development of refractive error and normal eye growth in a sample of predominantly Caucasian children ages 6 to 14 years. RESULTS: Cross-sectional results from 530 children ages 5 to 12 years in the 1st, 3rd, and 6th grades are presented. CONCLUSIONS: This sample's refractive error decreased toward emmetropia with age from an average of +0.73 D at age 6 years to an average of +0.50 D by age 12 years. Between the ages of 6 and 12 years, the vitreous chamber elongated (by 0.52 mm) and the crystalline lens power decreased (by 1.35 D); surprisingly, the crystalline lens thinned by 0.14 mm during this same time period.

California↗
PubMed1993

Comparison of cyclopentolate versus tropicamide cycloplegia in children.

This double masked study compares the cycloplegic effects of tropicamide 1% and cyclopentolate 1% in 20 nonstrabismic, nonamblyopic, hyperopic 6- to 12-year-old children with a mean refractive error = +1.48 +/- 1.10 diopters (D). Unlike previous studies which used only amplitude of accommodation to measure the depth of cycloplegia, this study compares refractive error as determined by retinoscopy, distance subjective refraction, and distance autorefraction (Canon R-1). In addition, we compare the amplitude of accommodation as measured by subjective push-up and objective autorefraction methods. There is no statistically significant difference between cyclopentolate and tropicamide for either cycloplegic retinoscopy or distance subjective refraction. Autorefraction measurement of refractive error shows a statistically significant but clinically unimportant bias (0.14 +/- 0.30 D) toward more hyperopia with cyclopentolate. Both drops reveal latent hyperopia, and the mean latencies are not statistically different between the two cycloplegic agents. Latent hyperopia is not systematically related to the degree of hyperopia after tropicamide, but this relation is significant after cyclopentolate. No differences were found between refractive results with either agent at 30 min compared to 60 min after drop instillation. When measured objectively with the autorefractor, accommodation is inhibited more effectively by cyclopentolate than by tropicamide. Our results suggest that although tropicamide is not as effective as cyclopentolate in inhibiting accommodation it is, nevertheless, a useful cycloplegic agent for measuring distance refractive error of low to moderate hyperopia in school-aged children.

Accommodation, Ocular↗
PubMed1992

Retinoscopic measurement of the refractive state of the rat.

Using retinoscopy, we measured the refractive state of 96 eyes of three different strains of rats: albino Sprague-Dawley, Royal College of Surgeons (RCS) with and without inherited retinal dystrophy, and lean and obese varieties of Zucker rats. Contrary to previous reports, we do not find consistent high hyperopia in the rat, but rather refractions that range from near emmetropia (-0.12 D) to extreme hyperopia (+18.95 D). This range of refractive errors suggests a poorly developed emmetropization mechanism in the rat, and that individual refractions should be performed on animals utilized in experiments where refractive state is critical.

Albinism, Ocular↗
PubMed1992

A video technique for phakometry of the human crystalline lens.

Accurate measurement of the dioptric power of the human crystalline lens is important in any study of ocular development and refractive error. Previous studies have used comparison ophthalmophakometry, measuring crystalline lens curvature and power from still flash photographs of Purkinje images I, III, and IV. This report presents a video-based technique for in vivo measurement of crystalline lens power suitable for use with children. The repeatability and validity of this video system were evaluated in comparison to a still photograph system through the measurement of anterior and posterior lens curvatures of 40 normal adults. The video system's repeatability (95% limits of agreement) was +/- 0.52 diopters for the anterior lens power, +/- 0.73 D for the posterior lens power, and +/- 0.88 D for the total lens power. The repeatability of the still flash photography system was +/- 0.78 D for the anterior, +/- 1.43 D for the posterior, and +/- 1.84 D for the lens power as a whole. An indirect method of calculating lens power using other ocular component measures gave a repeatability of +/- 1.78 D. The validity of the video system was improved by having the camera and the light source closer to the optic axis of the eye. The bias induced by having a more off-axis configuration (40 degrees separation between camera and light source) was a +0.10 D overestimation of surface power for the anterior and +0.73 D for the posterior lens surface power compared to a more coaxial arrangement (20 degrees between camera and light source). The use of video phakometry improved the repeatability and the validity of lens curvature measures relative to still flash photograph comparison ophthalmophakometry and to an indirect method of calculating lens power. This was achieved through the system's ability to analyze multiple frames, the use of a collimated light source, and the placement of the light source for the Purkinje images closer to the eye's optic axis.

Adult↗
PubMed1992

The repeatability of measurement of the ocular components.

Studies of the ocular components of refraction typically neglect issues of repeatability of measurement methods or analyze method comparison/repeatability data inappropriately using correlation. The authors have examined the repeatability of refractive error measures (retinoscopy, subjective refraction, and Canon R-1 autorefraction, noncycloplegic and cycloplegic), axial dimension measures (Allergan-Humphrey A-scan ultrasound), and corneoscopy (keratometry and KERA photokeratoscopy), and the agreement between different refractive error and corneal measurement methods on 40 pre-presbyopic normal adults. The authors plotted the difference versus the mean of two different measurement occasions (repeatability), or two different methods (agreement), to determine the bias (mean of the differences relative to zero) and 95% limits of agreement of each technique. The most reliable measure of refractive error was autorefraction with cycloplegia, with 95% limits of agreement of +/- 0.32 diopters. Cycloplegic autorefraction had no statistically significant bias compared to cycloplegic subjective refraction. Cycloplegic retinoscopy was the least reliable refractive error measure, with repeat measures on two separate occasions extending over 95% limits of agreement of +/- 0.95 D. Anterior chamber depth was reliable to +/- 0.29 mm, lens thickness to +/- 0.20 mm, and vitreous chamber depth to +/- 0.37 mm. Corneal curvature measures show keratometry to be more reliable (to +/- 0.87 D) than photokeratoscopy (+/- 2.02 D) with a statistically significant bias (paired t-test, P less than 0.0001) of 0.57 D flatter for photokeratoscopy.

Adult↗
PubMed1987

Refractive error changes in law students.

We report two separate studies: a retrospective survey and a longitudinal study; both were designed to assess the changes in refractive error of a group of young adult law students. The retrospective survey compared the previous spectacle correction to the current refractive error in the ocular examination records of 87 members of the class of 1982 law students who were examined at the University of California, Berkeley School of Optometry. Forty-one students (47.1% of the sample, 12.9% of the entire class of 318) increased at least -0.50D in myopia in at least one eye. In the longitudinal study, we followed 16 first year law students for 6 months, measuring refractive error. Five eyes (15.6%) became at least +0.50D more hyperopic, and 12 eyes (37.5%) became at least -0.50D more myopic. These data represent analysis of a small number of eyes over a short period of time. An adult myopic shift is nonetheless evident. A methodology for accumulation of more meaningful data on the specific ocular component changes responsible for this effect is discussed.

Adult↗
PubMed1987

Contact lens fitting relation and visual acuity in keratoconus.

The presence of visual decrement in keratoconus is widely recognized, but little is known about the effect of different contact lens fitting philosophies on visual acuity. We studied 10 eyes with keratoconus, each of which was tested with an automated visual acuity device while wearing rigid contact lenses of varying base curves and diameters. Lenses used were large, flat lenses and small, steep lenses, fitted from 0.4 mm flatter to 0.4 mm steeper than the average keratometric measurement in 0.1-mm increments, including parallel to the average corneal curvature. A small improvement in visual acuity was noted with the flat lenses, equalling approximately one-half line of visual acuity, which, although statistically significant, was not deemed to be clinically significant. In addition, a decrement in visual acuity of keratoconus patients with centrally placed cones was noted and is discussed.

Contact Lenses↗
PubMed1986

Artifact in optical pachometry with contact lenses in situ.

We describe a measurement artifact associated with the wearing of a contact lens during optical pachometry. The contact lens essentially magnifies the image of the cornea, creating a nonphysiological apparent increase in corneal thickness. This artifact ranges from 0.27 to 1.22% with four current extended wear hydrogel lenses, depending on lens thickness and index of refraction. The implications of this artifact are discussed relative to study design and interpretation of results for contact lens-induced corneal edema.

Contact Lenses↗
PubMedDate not supplied

Repeatability of corneal topography: the "corneal field".

BACKGROUND: The purpose of this study was to determine the interoccasion repeatability of keratometry, photokeratography, and videokeratography and to describe the "corneal field," a scheme for explaining videokeratography results. METHODS: A single examiner obtained corneal curvature measurements with a keratometer, a photokeratoscope, and the TMS-1 in 29 adult patients on two occasions. RESULTS: Estimates for the repeatability of keratometry were +/- 0.49 and +/- 0.65 diopters (D) for the horizontal and vertical meridians respectively. The repeatability of photokeratography was +/- 0.90 and +/- 1.21 D. We presented a rational method for presenting numeric videokeratographic data by temporally and spatially averaging corneal curvature values and grouping them into 24 regions. The repeatability of videokeratography with the TMS-1 was +/- 0.50 D centrally, +/- 0.65 D paracentrally, and +/- 0.80 to +/- 1.00 D in the midperiphery. CONCLUSIONS: Repeatability of the photokeratoscope for central measurements is considerably worse than the keratometer. The repeatability of videokeratography is worse toward the periphery. Refractive surgeons and contact lens investigators need to be aware of these limitations so that true change can be distinguished from measurement error.

Adult↗
PubMedDate not supplied

Quantifying corneal toricity from videokeratography with Fourier analysis.

BACKGROUND: Fourier analysis can be used to quantify corneal toricity from videokeratography data. This study measures the repeatability of Fourier-derived toricity values in normal adult corneas. METHODS: The Topographic Modeling System (TMS) was used to model the corneas of 29 subjects on two occasions, and Fourier analysis applied to the data. Repeatability of Fourier-derived toricity values between sessions was examined, and 95% limits of agreement were established. RESULTS: The 95% limits of agreement between sessions for the Fourier method were -0.02 +/- 0.16 diopters (D) and -0.5 +/- 5.7 degrees for toricity amount and axis, respectively. CONCLUSIONS: The Fourier method yields highly repeatable toricity values and thus provides a sensitive means of detecting longitudinal toricity change in normal corneas.

Adult↗
PubMedDate not supplied

Repeatability and validity of astigmatism measurements.

BACKGROUND: As more patients inquire about refractive surgical procedures, the measurement of astigmatism prior to surgery becomes more important in assessing refractive outcome. Knowledge of the repeatability of the astigmatism measurement allows one to distinguish a true change in cylinder power from measurement error. METHODS: Forty adults with structurally normal eyes and refractive errors were evaluated for the repeatability of astigmatic refractive error measures. Noncycloplegic and cycloplegic measurements of refractive astigmatism were made by retinoscopy, subjective refraction, and autorefraction. All measures were made at 2 visits within 2 weeks by the same examiner. Difference versus mean plots and the 95% limits of agreement of each technique determined the repeatability of a measurement and the agreement between the methods of measurement. RESULTS: The most reliable measure of astigmatic refractive error was cycloplegic autorefraction, with 95% limits of agreement of +/- 0.28 D, followed by noncycloplegic autorefraction (+/- 0.35 D) and cycloplegic subjective refraction (+/- 0.44 D). Noncycloplegic retinoscopy was the least reliable astigmatic refractive error measure, with interoccasion 95% limits of agreement of +/- 1.02 D. The most repeatable measurement of cylinder axis was cycloplegic autorefraction; none of the measurements differed by 10 degrees or more. The least repeatable measurement was noncycloplegic retinoscopy; 40% of the measurements differed by 10 degrees or more. CONCLUSION: For studies seeking to measure changes in astigmatism in normal eyes, cycloplegic autorefraction is the method of choice.

Adult↗