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1.
Optom Vis Sci ; 98(10): 1203-1209, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34620781

RESUMO

SIGNIFICANCE: Anterior eye shape measurements are important for clinical contact lens fitting. The detailed assessment of measurement repeatability using the Eye Surface Profiler (ESP; Eaglet Eye B.V., AP Houten, the Netherlands) allows for more reliable interpretation of eye surface topography measurements. PURPOSE: This study aimed to determine the repeatability of the ESP for anterior central corneal power and anterior eye surface height measurements. METHODS: A Badal optometer was mounted on the ESP to provide an external fixation target with appropriate accommodation control and refractive correction. Forty-five healthy young adults underwent two sessions of anterior eye measurements, separated by 20 minutes, using the ESP. In each session, three consecutive scans were captured. Sagittal height data were obtained from 8-mm central cornea and from 8- to 14-mm diameter (encompassing the corneal periphery and anterior sclera). Anterior corneal powers were determined from the central cornea. Intersessional and intrasessional repeatability values were determined as coefficients of repeatability and root mean square error differences. RESULTS: Sagittal height intersessional coefficients of repeatability for central nasal (5 µm) and central temporal (7 µm) were better than peripheral nasal (24 µm) and peripheral temporal (21 µm) regions. Sagittal height intrasessional coefficients of repeatability were 9, 8, 28, and 31 µm for central nasal, central temporal, peripheral nasal, and peripheral temporal regions, respectively. Intersessional coefficients of repeatability of mean sphere, 90/180° (J0) astigmatism, and oblique (J45) astigmatism were 0.67, 0.22, and 0.13 D, respectively, with corresponding intrasessional coefficients of repeatability of 1.27, 0.21, and 0.27 D. CONCLUSIONS: The modified measuring procedure for the ESP used in this study provides highly repeatable sagittal height measurements in the central cornea but is less repeatable in the corneal periphery and scleral region. Results of the current study can be considered when using ESP in the interpretation of anterior eye surface shape measurements and in contact lens fitting and design.


Assuntos
Astigmatismo , Córnea , Acomodação Ocular , Córnea/diagnóstico por imagem , Topografia da Córnea , Humanos , Reprodutibilidade dos Testes , Esclera , Adulto Jovem
2.
Ophthalmic Physiol Opt ; 41(6): 1346-1354, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34605581

RESUMO

PURPOSE: Prolonged nearwork has been implicated in myopia progression. Accommodation responses of young-adult myopes wearing different multifocal contact lenses were compared. METHODS: Twenty adults, 18-25 years, with myopia (spherical equivalent refraction -0.50 to -5.50 D, mean -2.1 ± 1.6 D) wore five lens types in random order: Proclear single vision distance (SV), MiSight concentric dual-focus +2.00 D Add (MS), Biofinity aspheric centre distance +1.50 D Add (CD1) and +2.50 D Add (CD2) (all Coopervision), and NaturalVue aspheric (Visioneering Technologies) (NVue). Using a Grand-Seiko WAN-5500 autorefractor with binocular correction and viewing right eye accommodative responses were measured after a 10 min adaptation period at 4.0, 1.0, 0.5, 0.33 and 0.25 m distances. Dynamic measurements were taken for 4 s at 6 Hz. Accommodative stimuli and responses were referenced to 4 m (i.e., refraction differences between 4 m and nearer distances). Accommodation lags and refraction instabilities (standard deviations of dynamic responses) were determined. For comparison, results were obtained for an absolute presbyopic eye, where trial lenses counteracted the accommodation stimulus. RESULTS: For SV and MS, accommodation responses were similar to the stimulus values. For aspheric lenses CD1, CD2 and NVue, accommodation responses were approximately 1.0 D lower across the stimulus range than with SV and MS, and rates of change were approximately 0.84 D per 1 D stimulus change. MS produced greater refraction instabilities than other lenses. For the presbyope, changes in refraction matched the trial lenses, indicating that corrections due to measurement through the different lenses were not needed. CONCLUSION: Reductions in accommodation response occurred in young myopes wearing aspheric multifocal contact lenses independent of the labelled 'add' power. The concentric dual-focus MS lens produced minimal lags but had greater instability than the other lenses. The results indicate that the mechanism of multifocal contact lenses slowing myopia progression is unlikely to be through relaxing accommodation, at least in young adults.

3.
Biomed Opt Express ; 12(8): 4969-4981, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34513236

RESUMO

The Stiles-Crawford effect of the first kind (SCE) is the phenomenon in which light entering the eye near the center of the pupil appears brighter than light entering near the edge. Previous investigations have found an increase in the directionality (steepness) of the effect as the testing location moves from the center of the visual field to parafoveal positions, but the effect of central field size has not been considered. The influence of field size on the SCE was investigated using a uniaxial Maxwellian system in which stimulus presentation was controlled by an active-matrix liquid crystal display. SCE directionality increased as field size increased from 0.5° to 4.7° diameter, although this was noted in four mild myopes and not in two emmetropes. The change with field size was supported by a geometric optics absorption model.

4.
Ophthalmic Physiol Opt ; 41(6): 1222-1230, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34427946

RESUMO

PURPOSE: Approaches are developed to determine relative retinal magnifications in anisometropic patients undergoing cataract surgery; these can be used to balance between full spectacle corrections with equal intraocular lens (IOL) powers and a pure IOL power correction. METHODS: The analysis started from the original and pseudophakic Navarro eye models, where in the latter case an IOL replaced the natural lens. A third model was a simplified Navarro-IOL model with a single surface cornea and a thin lens. These models were manipulated by altering vitreous length, corneal power and lens position. Retinal image sizes were determined for both full IOL corrections and full spectacle corrections by raytracing and approximate equations. Relative magnification (RM) was determined as the ratio of retinal image size of an eye to that of the appropriate standard eye. RESULTS: For raytracing and full IOL correction, vitreous length led to RM change of 5%/mm, while for corneal power and IOL position this was -0.4%/D and 1.4%/mm, respectively. For raytracing and spectacle correction, effects were 0%/D (vitreous depth), -1.6%/D (corneal power) and +1.0%/mm (IOL position). For full IOL correction, the approximate RM calculations were highly accurate. For spectacle correction, the approximate RM calculations were exact for vitreous length changes, reasonably accurate for corneal power changes but very inaccurate for changes in anterior chamber depth. CONCLUSION: Relative magnification approximations may be useful to assess the risk of aniseikonia in anisometropic patients targeted for postoperative emmetropia. Some of these patients would be corrected best by a combination of spectacles and IOLs.

5.
Ophthalmic Physiol Opt ; 41(5): 1110-1118, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34387885

RESUMO

PURPOSE: To measure the Stiles-Crawford effect of the first kind (SCE-I), corresponding to central vision, with innovative technology to evaluate changes in the directionality and photoreceptor alignment with accommodation. METHODS: A uniaxial Maxwellian system (spot size in pupil 0.5 mm diameter) was employed, incorporating a spatial light modulator to flicker at 2 Hz between two 2.3° fields corresponding to test (peripheral pupil) and reference (pupil centre) positions. Participants determined thresholds at 13 positions along the horizontal pupil meridian by indicating if the test field was brighter or dimmer than the reference field. Thresholds were determined by a staircase procedure after four reversals at each pupil location. After pupil dilation, seven emmetropes were tested at 0 D to 6 D accommodation stimulus levels in 2 D intervals. Data were fit by the Gaussian function, both when the fits were unforced or forced to pass through the sensitivity expected for the reference point. Directionality (ρ) and peak location values ( x max ) were determined for unforced and forced fits. RESULTS: Regression slopes for ρ as a function of accommodation stimulus were not significant. There was a tendency for x max to shift temporally with increasing accommodation across the 6 D stimulus range. This was not significant for regression fitting (-0.059 mm/D, R2  = 0.06, p = 0.20), but a paired t-test for 0 and 6 D stimuli showed a weakly significant change of 0.62 mm (p = 0.05). The differences between the two fitting approaches were small and non-significant. CONCLUSIONS: Directionality did not change with accommodation, but the pupil peak location showed a significant temporal shift of approximately 0.62 mm with 6 D accommodation stimulus. It is possible that substantial changes in the directionality and a shift in the direction of peak location might occur at very high levels of accommodation.

6.
Biomed Opt Express ; 12(5): 2550-2556, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34123486

RESUMO

Cataract-induced refractive change (CIRC) is the change in refraction induced by a cataract. It can amount to several diopters (D). It alters predicted errors in refraction following cataract surgery through changes in axial length measurement. This study determined the effect of CIRC on the accuracy of intraocular lens power formula predictions of refraction in 872 eyes of 662 patients. Regression of results gave -0.030 D prediction error per 1 D of CIRC, i.e. cataract-induced myopia and hyperopia tended to yield postoperative hyperopia and myopia, respectively. Theoretical determinations with a model eye supported this result. There was significant correlation of nuclear cataract opalescence with CIRC. Although these effects are difficult to identify based on changes in refraction, if biometers were able to identify cataract density and automatically adjust axial length measurement, IOL power predictions might improve.

7.
Appl Opt ; 60(4): A173-A178, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33690367

RESUMO

We introduce the digital holographic microscope for recording in vivo human eye retinal structures. Current eye imaging technologies cannot provide images with resolutions better than 1 µm within depths of a few hundred micrometers. This can be improved with digital holography, in which a hologram of the eye captured with digital camera contains information about structures over the full depth of the eye. This information can be reconstructed either optically or numerically. Our hologram recording scheme utilizes working principles of the off-axis digital holographic microscope, designed for reflective micro-object investigation. The eye cornea and lens form the microscope objective. We can record in vivo digital holograms of the human eye retina with resolution after reconstruction of at least 1.3 micrometer.


Assuntos
Holografia/métodos , Microscopia/métodos , Retina/diagnóstico por imagem , Algoritmos , Desenho de Equipamento , Holografia/instrumentação , Humanos , Microscopia/instrumentação , Processamento de Sinais Assistido por Computador
9.
Ophthalmic Physiol Opt ; 41(4): 664-672, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33769593

RESUMO

PURPOSE: To quantify the effect of a single scleral lens design on visual acuity and ocular higher-order aberrations in eyes with post-LASIK ectasia, keratoconus and pellucid marginal degeneration (PMD) that could not achieve satisfactory vision with spectacles or soft contact lenses. METHODS: Forty-six eyes of 28 participants fitted with diagnostic scleral lenses (KeraCare) were analysed, including 19, 15 and 12 eyes with post-LASIK ectasia, keratoconus and PMD, respectively. Corrected distance visual acuity (CDVA) and ocular aberrations were measured prior to lens wear and during lens wear after 60 min of settling. An i-Trace aberrometer was used to determine aberrations over a 4.5 mm diameter pupil. RESULTS: Before lens wear, the median (95% confidence interval) values across all groups were: CDVA 0.30 (0.30, 0.40) logMAR, spherical equivalent refraction -2.75 (-5.25, -2.12) D, cylindrical refraction 3.75 (2.50, 5.00) D, higher-order-root-mean-square error (HO-RMS) 0.90 (0.64, 1.03) µm and vertical coma co-efficient C(3,-1) -0.32 (-0.42, -0.12) µm. RMS coma of 0.52 (0.40, 0.74) µm was higher for the keratoconus group than for the other groups (p < 0.05). During lens wear, values improved considerably across all groups: CDVA 0.0 (0.0, 0.00) logMAR, spherical equivalent refraction -0.50 (-0.75, +0.50) D, cylindrical refraction 0.50 (0.00, 0.50) D, HO-RMS 0.32 (0.26, 0.42) µm and C(3,-1) +0.12 (+0.02, +0.19) µm (all p < 0.001 compared to pre-lens wear). While reduced significantly, RMS coma remained higher in the keratoconus group at 0.35 (0.31, 0.52) µm than in the post-LASIK ectasia and PMD groups at 0.17 (0.12, 0.21) µm and 0.07 (0.02, 0.46) µm, respectively (p < 0.05). CONCLUSIONS: The KeraCare scleral contact lens reduced ocular aberrations and improved visual acuity in patients with post-LASIK ectasia, keratoconus and PMD. The sign of vertical coma changed in keratoconus and PMD.

10.
Ophthalmic Physiol Opt ; 41(2): 401-408, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33609050

RESUMO

Third-order equations are well known for determining sagittal and tangential powers of a thin lens, corresponding to an eye rotating behind a lens to view objects away from the optical axis of the lens. These equations are referenced to the back surface of the lens and do not take into account the peripheral thickness of the lens. They do not give the same results as finite raytracing at small angles in which powers are referenced to the vertex sphere, which is the same distance from the centre-of-rotation for all object angles. Modified forms of the third-order sagittal and tangential image vergence error equations are developed to overcome the discrepancies. These are used to determine Tscherning ellipses for zero oblique astigmatism and zero mean oblique power error. While solutions to oblique astigmatism are not affected by the modifications, there are considerable changes to mean oblique error solutions.


Assuntos
Astigmatismo/terapia , Óculos/tendências , Modelos Teóricos , Óptica e Fotônica , Refração Ocular/fisiologia , Astigmatismo/fisiopatologia , Desenho de Equipamento , Humanos
11.
Exp Eye Res ; 203: 108435, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33421425

RESUMO

PURPOSE: Convergence plays a fundamental role in the performance of near visual tasks. We measured the effect of two levels of convergence on anterior scleral thickness and shape in emmetropes, low to moderate myopes and high myopes. METHODS: Forty-five healthy young adults aged between 18 and 35 years including 15 emmetropes, 15 low/moderate myopes, and 15 high myopes were recruited. Anterior segment optical coherence tomography and eye surface profilometry were used to evaluate the anterior scleral thickness (nasal only, n = 42) and shape (n = 40), before and during two visual tasks involving 9° and 18° convergence, in those participants with complete and reliable data. RESULTS: Convergence led to a thickening of the total anterior eye wall (5.9 ± 1.4 µm) and forward movement (10 ± 2 µm) of the nasal anterior scleral surface (both p < 0.001). Larger changes were found at 18° than at 9° convergence and in more peripheral nasal scleral regions. There was a significant association between total wall thickening and forward movement of the scleral surface. Refractive group was not a significant main effect, but there were significant interactions between refractive group and the thickness changes with convergence in different scleral regions. CONCLUSION: During convergence, the biomechanical forces acting on the eye lead to nasal anterior scleral thickening and forward movement of the nasal scleral surface.


Assuntos
Segmento Anterior do Olho/fisiopatologia , Convergência Ocular/fisiologia , Esclera/fisiopatologia , Adolescente , Adulto , Segmento Anterior do Olho/diagnóstico por imagem , Emetropia/fisiologia , Feminino , Humanos , Masculino , Miopia/patologia , Oftalmoscopia , Tamanho do Órgão , Esclera/diagnóstico por imagem , Tomografia de Coerência Óptica , Adulto Jovem
12.
Cont Lens Anterior Eye ; 44(4): 101361, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32830067

RESUMO

PURPOSE: Myopia prevalence has increased in recent years, including the levels of high myopia. While myopia has been associated with scleral remodelling and changes in posterior scleral shape, there has been little research examining how myopia affects in-vivo anterior sclera shape. We compared anterior scleral shape in emmetropes, low to moderate myopes, and high myopes. METHODS: In this prospective study, the Eye Surface Profiler instrument was used to quantify anterior eye surface shapes of forty-five young adult participants (58 % females) aged between 18 and 35 years, including 15 emmetropes, 15 low to moderate myopes, and 15 high myopes. Sagittal height and axial radius of curvature of regions over the nasal and temporal corneal periphery and anterior sclera were exported and analysed. RESULTS: After quality control of the data, 39 and 43 subjects had data analysed from the nasal and temporal sides, respectively. The nasal sides of the surfaces of the corneal periphery and anterior sclera had greater sagittal height in high myopes than in emmetropes across all regions (mean sagittal heights 2.44 ± 0.07 and 2.21 ± 0.04 mm, respectively, p = 0.02), but no significant differences were found between low to moderate myopes with emmetropes or with high myopes. No significant refractive group differences occurred for temporal anterior eye surface height. High myopes' nasal-temporal asymmetry of sagittal height was less than of emmetropes (means 0.20 ± 0.07 and 0.46 ± 0.06 mm, respectively, p = 0.02). High myopes also exhibited less nasal-temporal axial radius of curvature asymmetry than emmetropes (mean 0.35 ± 0.08 and 0.71 ± 0.08 mm, respectively, p = 0.01) across all regions. CONCLUSIONS: High myopes exhibited a different anterior eye surface shape than emmetropes, having greater sagittal height in the nasal corneal periphery and anterior sclera. There was less nasal-temporal asymmetry of sagittal height and axial radius of curvature in high myopes than in emmetropes. Asymmetric growth of the eye associated with myopia development may be the underlying reason. These findings have implications for design of contact lenses, particularly soft and larger rigid lenses such as mini-sclerals.


Assuntos
Emetropia , Miopia , Adolescente , Adulto , Córnea , Feminino , Humanos , Masculino , Estudos Prospectivos , Esclera , Adulto Jovem
13.
Biomed Opt Express ; 11(10): 5860-5870, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33149991

RESUMO

Optical biometry uses interferometry to measure the axial length (AL) of the eye. Traditionally, one-variable regression formulas have converted the optical path length measured by a biometer to a geometric AL. An alternate calculation of axial length sums the individual segments of the eye (sum-of-segments AL). This calculation has been shown to improve predictions of some intraocular lens power formulas when used in place of traditional axial length. Sum-of-segments ALs are determined from 13 refractive index models. As measured in 1695 eyes, these yield different ocular axial lengths. A path to standardization from these models is presented.

14.
Ophthalmic Physiol Opt ; 40(5): 660-668, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32776575

RESUMO

PURPOSE: To determine whether monocularly- and binocularly-induced spherical and meridional blur and aniseikonia had similar effects on stereopsis thresholds. METHODS: Twelve participants with normal binocular vision viewed McGill modified random dot stereograms to determine stereoacuities in a four-alternative forced-choice procedure. Astigmatism was induced by placing trial lenses in front of the eyes. Twenty-three conditions were used, consisting of zero (no lens), +1 D and +2 D spheres and cylinders at axes 180, 45 and 90 in front of the right eye, and the following binocular combinations of both lens powers: R × 180/L × 180, R × 45/L × 45, R × 90/L × 90, R sphere/L sphere, R × 180/L × 90, R × 45/L × 135, R × 90/L × 180. Aniseikonia was induced by placing magnifying lenses in front of the eyes. Twenty-three conditions were used, consisting of zero, 6% and 12% overall magnification and both magnifications at axes 180, 45 and 90 in front of the right eye only, and the following binocular combinations using 3% and 6% lenses: R × 90/L × 90, R × 45/L × 45, R × 180/L × 180, R overall/L overall, R × 90/L × 180, R × 45/L × 135, and R × 180/L × 90. RESULTS: Stereopsis losses for binocular blur effects with parallel axes (non-anisometropic) were the same as for monocular blur effects of the same axes, and these were strongly dependent on axis (spherical blur and ×90 had the greatest effects). Binocular blur effects with orthogonal axes had greater effects than with parallel axes, with the axis combination of the former having no effect (e.g. R × 90/L × 180 was similar to R × 45/L × 135). For induced aniseikonia, splitting the magnifications between the eyes improved stereopsis slightly, and the effects were not dependent on axis. CONCLUSION: Binocular blur affects stereopsis similarly to monocular meridional blur if axes in the two eyes are parallel, whereas the effect is greater if the axes are orthogonal. In meridional aniseikonia, splitting magnification between the right and left lenses produces a small improvement in stereopsis that is independent of axis direction and right/left combination.


Assuntos
Aniseiconia/fisiopatologia , Percepção de Profundidade/fisiologia , Refração Ocular/fisiologia , Visão Binocular/fisiologia , Acuidade Visual , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
15.
Ophthalmic Physiol Opt ; 40(4): 482-490, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32495362

RESUMO

PURPOSE: The sclera plays an important role in the biomechanical stability of the eye. We aimed to examine if changes in the shape of the anterior sclera occur in response to accommodation and convergence. METHODS: Thirty-six healthy young adult participants aged between 18 and 30 years including 18 myopes (-0.5 to -4.0 D) and 18 emmetropes (+0.5 to -0.25 D) were recruited. Eye surface profilometry was used to evaluate the anterior eye surface shape before and during visual tasks involving accommodation (5.0 D demand), simulated convergence (9° demand) and their combination. The changes in the sagittal height and axial radius of curvature of the nasal (n = 25) and temporal (n = 31) corneal periphery and anterior sclera were analysed in those participants with complete and reliable data on these sides. RESULTS: Significant changes were confined to the nasal anterior scleral surface. A significant forward movement of the surface accompanied accommodation (mean change: 5 ± 2 µm), convergence (19 ± 6 µm), and their combination (16 ± 6 µm). There was flattening with convergence (0.092 ± 0.044 mm) and with the combination of accommodation and convergence (0.201 ± 0.071 mm). The changes in response to accommodation and convergence increased peripherally. Changes were not significantly different between low to moderate myopes and emmetropes. CONCLUSIONS: Accommodation and simulated convergence affect the nasal anterior scleral shape, with the greatest changes associated with convergence and being most evident in the more peripheral nasal scleral regions.


Assuntos
Acomodação Ocular/fisiologia , Emetropia/fisiologia , Esclera/diagnóstico por imagem , Tomografia de Coerência Óptica/métodos , Adolescente , Adulto , Córnea/diagnóstico por imagem , Feminino , Voluntários Saudáveis , Humanos , Masculino , Adulto Jovem
16.
J Opt Soc Am A Opt Image Sci Vis ; 37(4): A122-A132, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32400532

RESUMO

Lighting conditions nominated for color vision testing are many and varied. The recommendation of CIE color rendering index (CIE CRI) ≥90 and correlated color temperature of close to 6500 K is widely made for color vision testing generally. With the demise of incandescent and fluorescent lighting and their replacement by light-emitting diodes (LEDs), this is an opportune time to revisit the recommendation. In this paper, we consider the current sources, acceptable and unacceptable, and improvements to the recommendation as it applies to the Farnsworth-Munsell 100 Hue Test (FM100Hue Test). We conclude that there is no need to treat LEDs as a special case but propose a modified CRI measure.

17.
Ophthalmic Physiol Opt ; 40(3): 323-332, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32128857

RESUMO

PURPOSE: Stereopsis depends on horizontally disparate retinal images but otherwise concordance between eyes. Here we investigate the effect of spherical and meridional simulated anisometropia and aniseikonia on stereopsis thresholds. The aims were to determine effects of meridian, magnitude and the relative effects of the two conditions. METHODS: Ten participants with normal binocular vision viewed McGill modified random dot stereograms through synchronised shutter glasses. Stereoacuities were determined using a four-alternative forced-choice procedure. To induce anisometropia, trial lenses of varying power and axes were placed in front of right eyes. Seventeen combinations were used: zero (no lens) and both positive and negative, 1 and 2 D powers, at 45, 90 and 180 axes; spherical lenses were also tested. To induce aniseikonia 17 magnification power and axis combinations were used. This included zero (no lens), and 3%, 6%, 9% and 12% at axes 45, 90 and 180; overall magnifications were also tested. RESULTS: For induced anisometropia, stereopsis loss increased as cylindrical axis rotated from 180° to 90°, at which the loss was similar to that for spherical blur. For example, for 2 D meridional anisometropia threshold increased from 1.53 log sec arc (i.e. 34 sec arc) for x 180 to 1.89 log sec arc (78 sec arc) for x 90. Anisometropia induced with either positive or negative lenses had similar detrimental effects on stereopsis. Unlike anisometropia, the stereopsis loss with induced meridional aniseikonia was not affected by axis and was about 64% of that for overall aniseikonia of the same amount. Approximately, each 1 D of induced anisometropia had the same effect on threshold as did each 6% of induced aniseikonia. CONCLUSION: The axes of meridional anisometropia but not aniseikonia affected stereopsis. This suggests differences in the way that monocular blur (anisometropia) and interocular shape differences (aniseikonia) are processed during the production of stereopsis.


Assuntos
Aniseiconia/fisiopatologia , Anisometropia/fisiopatologia , Simulação por Computador , Percepção de Profundidade/fisiologia , Óculos , Acuidade Visual , Adulto , Aniseiconia/terapia , Anisometropia/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Visão Binocular , Adulto Jovem
18.
Surv Ophthalmol ; 65(2): 239-249, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31622629

RESUMO

We evaluate the impact of duration on the treatment effect of multifocal spectacle lenses used to inhibit myopia progression in children. A systematic literature search identified randomized controlled trials where multifocal lenses were prescribed as the intervention, with single-vision lenses as the control. Nine randomized control trials involving 1,701 children aged 8-13 years were included in the meta-analysis. Treatment effects, that is, differences in spherical equivalent refraction between intervention and nonintervention groups, were analyzed over both 6- and 12-month intervals. As treatment duration increased, effectiveness reduced. In 6-month intervals, treatment effects were 0.07 D (95 % CI 0.02, 0.13), 0.03 D (95% CI -0.02, 0.08), and 0.02 D (95% CI -0.05, 0.11) for baseline to 6, 6-12, and 12-18 months, respectively. For 12-month intervals, treatment effects were 0.21 D (95% CI 0.12, 0.29), 0.11 D (95% CI 0.03, 0.19), and 0.12 D (95% CI -0.01, 0.25) for baseline to 12, 12-24, and 24-36 months, respectively. Even during the second 6 months of wear, the ability of multifocal spectacle lenses to inhibit myopia progression was reduced. It is not appropriate to extrapolate the treatment effect observed in the first 6 months or 12 months to estimate the likely future benefit of treatment.


Assuntos
Óculos , Miopia Degenerativa/terapia , Refração Ocular/fisiologia , Acuidade Visual , Criança , Progressão da Doença , Humanos , Miopia Degenerativa/fisiopatologia , Fatores de Tempo
19.
Biomed Opt Express ; 11(12): 7376-7394, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33409003

RESUMO

A combination of human subject data and optical modelling was used to investigate unexpected nasal-temporal asymmetry in peripheral refraction with an aspheric myopia control lens. Peripheral refraction was measured with an auto-refractor and an aberrometer. Peripheral refraction with the lens was highly dependent upon instrument and method (e.g. pupil size and the number of aberration orders). A model that did not account for on-eye conformation did not mirror the clinical results, but a model assuming complete lens conformation to the anterior corneal topography accounted for the positive shift in clinically measured refraction at larger nasal field angles. The findings indicate that peripheral refraction of highly aspheric contact lenses is dependent on lens conformation and the method of measurement. These measurement methods must be reported, and care must be used in interpreting results.

20.
Optom Vis Sci ; 96(9): 695-705, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31479025

RESUMO

SIGNIFICANCE: Clinicians who administer the Farnsworth-Munsell D-15 test need to pay attention to the quality and quantity of lighting and the time that they allow for completion of the test, and all repeat attempts need to be included in reports on compliance with color vision standards. PURPOSE: The validity of the Farnsworth-Munsell D-15 has been questioned because practice may allow significantly color vision-deficient subjects to pass. In this article, we review the influence of practice and other factors that may affect the performance. These relate to both the design and the administration of the test. METHODS: We review the literature and present some calculations on limitations in the colorimetric design of the test, quantity and quality of lighting, time taken, and repeat attempts. RESULTS: In addition to the review of the literature, color differences and luminance differences under selected sources are calculated, and the increases in luminance clues under some sources and for protanopes are illustrated. CONCLUSIONS: All these factors affect the outcome of the test and need specification and implementation if the test is to be applied consistently and equitably. We recommend the following: practitioners should never rely on a single color vision test regardless of the color vision standard; lighting should be Tcp '' 6500 K and Ra > 90; illuminance levels should be between 200 and 300 lux if detection of color vision deficiency is a priority or between 300 and 1000 lux if the need is to test at the level where illuminance has minimal influence on performance; illuminance should be reported; time limits should be set between 1 and 2 minutes; repeat testing (beyond the specified test and one retest) should be carried out only with authorization; and initial and repeated results should be reported. A set of test instructions to assist in the consistent application of the test is provided in the Appendix.


Assuntos
Testes de Percepção de Cores/métodos , Testes de Percepção de Cores/normas , Defeitos da Visão Cromática/diagnóstico , Adulto , Algoritmos , Visão de Cores/fisiologia , Defeitos da Visão Cromática/fisiopatologia , Colorimetria , Humanos , Iluminação , Masculino
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