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INTRODUCTION: To quantitatively assess visual performance and patient satisfaction during photochromic contact lens (CL) wear in an indoor environment. METHODS: This observational study comprised 82 eyes of 41 healthy subjects (mean age ± standard deviation, 21.7 ± 0.7 years) who had no ophthalmic diseases except for refractive errors at Kitasato University in 2021. We prospectively compared visual acuity, kinetic visual acuity, functional (time-dependent) visual acuity, the maintaining rate of visual acuity, the response time, contrast sensitivity function, higher-order aberrations, and patient satisfaction score for overall vision in such subjects during photochromic and non-photochromic CL wear in such an environment. RESULTS: The kinetic visual acuity at 30 km/h was 0.32 ± 0.21 and 0.41 ± 0.24 in the photochromic and non-photochromic CL groups, respectively (p = 0.008). The kinetic visual acuity at 60 km/h was 0.32 ± 0.21 and 0.41 ± 0.24, respectively (p = 0.034). The functional visual acuity was 0.00 ± 0.21 and 0.05 ± 0.25, respectively (p = 0.030). The average response time was 1.19 ± 0.15 s and 1.23 ± 0.15 s, respectively (p = 0.029). The patient satisfaction score for overall visual performance was 4.22 ± 0.11 and 3.59 ± 0.68, respectively (p < 0.001). Otherwise, we found no significant differences in visual acuity, the maintaining rate, higher-order aberrations, or contrast sensitivity function (p = 0.116, p = 0.053, p = 0.371, or p = 0.943). We found no apparent complications such as ocular discomfort, superficial punctate keratitis, conjunctival injection, or infectious keratitis during the observation period. CONCLUSIONS: According to our experience, the photochromic CL showed good visual quality, especially in terms of kinetic and functional visual acuities and subsequent high patient satisfaction, even in an indoor environment, suggesting its viability of visual correction not only in daily activities but also in indoor sports activities.
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This study was aimed to evaluate the relationship between the area under the log contrast sensitivity function (AULCSF) and several optical factors in eyes suffering mild cataract. We enrolled 71 eyes of 71 patients (mean age, 71.4 ± 10.7 (standard deviation) years) with cataract formation who were under surgical consultation. We determined the area under the log contrast sensitivity function (AULCSF) using a contrast sensitivity unit (VCTS-6500, Vistech). We utilized single and multiple regression analyses to investigate the relevant factors in such eyes. The mean AULSCF was 1.06 ± 0.16 (0.62 to 1.38). Explanatory variables relevant to the AULCSF were, in order of influence, logMAR best spectacle-corrected visual acuity (BSCVA) (p < 0.001, partial regression coefficient B = -0.372), and log(s) (p = 0.023, B = -0.032) (adjusted R2 = 0.402). We found no significant association with other variables such as age, gender, uncorrected visual acuity, nuclear sclerosis grade, or ocular HOAs. Eyes with better BSCVA and lower log(s) are more susceptible to show higher AULCSF, even in mild cataract subjects. It is indicated that both visual acuity and intraocular forward scattering play a role in the CS function in such eyes.
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This study was aimed to determine the effect of the amount of astigmatism on distance visual acuity, and to provide a prediction formula of visual acuity according to astigmatism, in a presbyopic population. We comprised 318 eyes of 318 consecutive patients (158 phakic and 160 pseudophakic subjects) without any eye diseases, except for refractive errors with astigmatism of 3 diopter or less. We assessed the relationship of the spherical equivalent visual acuity (SEVA) with astigmatism, and also provided a regression formula of visual acuity according to astigmatism in such subjects. We found a significant correlation between the SEVA and the amount of astigmatism (r = 0.715, p < 0.001) in the entire study population. We obtained similar results, not only in phakic eyes (r = 0.718, p < 0.001), but also in pseudophakic eyes (r = 0.717, p < 0.001). The regression formula was expressed as follows: y = 0.017x2 + 0.125x - 0.116 (R2 = 0.544), where y = logMAR SEVA, and x = astigmatism. We also found no significant differences in the SEVA for matched comparison among the with-the-rule (WTR), against-the-rule (ATR), and oblique (OBL) astigmatism subgroups (p = 0.922). These regression formulas may be clinically beneficial not only for estimating the visual prognosis after astigmatic correction, but also for determining the surgical indication of astigmatic correction.
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Astigmatismo/patología , Presbiopía/patología , Agudeza Visual/fisiología , Anciano , Anciano de 80 o más Años , Envejecimiento/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Seudofaquia/patología , Refracción OcularRESUMEN
PURPOSE: Regional variations of the preoperative biometry can affect the refractive accuracy of cataract surgery. We aimed to compare the preoperative biometric data for cataract surgery between two domestic institutions. METHODS: We retrospectively reviewed the preoperative biometric data of 673 consecutive eyes undergoing standard cataract surgery at Miyata Eye Hospital (Miyazaki; M group) and Kitasato University Hospital (Kanagawa; K group), and compared these data between the two groups. RESULTS: We found significant differences in the mean keratometric readings (44.39 ± 1.56 D vs. 44.09 ± 1.74 D) (unpaired t test, p = 0.034), the anterior chamber depth (3.14 ± 0.43 mm vs. 3.46 ± 0.62 mm) (p < 0.001), the axial length (23.98 ± 1.62 mm vs. 24.59 ± 1.82 mm) (p < 0.001), and the lens thickness (4.64 ± 0.48 mm vs. 4.37 ± 0.62 mm) (p < 0.001), in the M and K groups, respectively. Otherwise, we found no significant differences in corneal astigmatism (p = 0.104), or central corneal thickness (p = 0.480) between the two groups. For subgroup analysis, the prediction error (0.06 ± 0.47 D) in the M group was significantly more hyperopic than that (- 0.09 ± 0.54 D) in the K group (p = 0.006). CONCLUSIONS: There were significant differences in the mean keratometric readings, the anterior chamber depth, the axial length, and the lens thickness, by approximately 0.3 D, 0.3 mm, 0.6 mm, and 0.3 mm, respectively. Regional variations of the preoperative biometry did exist to some extent, and were not clinically negligible, in consideration of the precise IOL power calculation and the subsequent refractive accuracy of cataract surgery. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trial Registry (000037994).
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Extracción de Catarata , Catarata , Lentes Intraoculares , Biometría , Catarata/diagnóstico , Humanos , Implantación de Lentes Intraoculares , Refracción Ocular , Estudios RetrospectivosRESUMEN
PURPOSE: The relationship between conventional keratometry and total keratometry has not been fully investigated. This study was aimed at conventional keratometry measured with the automated keratometer and total keratometry with the corneal tomographer in ophthalmologically normal subjects. METHODS: We enrolled fifty eyes of 50 consecutive subjects (mean age ± standard deviation, 34.9 ± 8.0 years) who have no ophthalmologic diseases, other than refractive errors, with no history of ocular surgery. Conventional keratometry was measured with the automated keratometer. The total keratometry, the true net power (TNP), and the total corneal refractive power (TCRP) were measured with the Scheimpflug camera, and the real power (RP) was measured with anterior segment optical coherence tomography (As-OCT). Anterior keratometries (Km and AvgK) were also measured with the Scheimpflug camera and the As-OCT, respectively. RESULTS: Conventional keratometry was 43.64 ± 1.48 D, which was significantly higher than the TCRP (42.94 ± 1.45 D, p = 0.042), the TNP (42.13 ± 1.37 D, p < 0.001), and the RP (42.62 ± 1.39 D, p = 0.001, Dunnett's test). We found significant correlations between conventional keratometry and each total corneal power (the TCRP (Pearson's correlation coefficient r = 0.986, p < 0.001), the TNP (r = 0.986, p < 0.001), the RP (r = 0.987, p < 0.001), the Km (r = 0.990, p < 0.001), and the AvgK (r = 0.991, p < 0.001)). The intraclass correlations of conventional keratometry with the TCRP, the TNP, the RP, the Km, and the AvgK were 0.986, 0.983, 0.985, 0.990, and 0.990, respectively. We found no significant differences in the keratometric data measured with the automated keratometer, the Scheimpflug camera, and the As-OCT (ANOVA, p = 0.729). CONCLUSIONS: Conventional keratometry was significantly larger than total keratometry, by approximately 0.70 to 1.52 D, in ophthalmologically normal subjects. By contrast, there were no significant differences in the keratometric data among the three devices. It is suggested that conventional keratometry overestimates the total corneal power in daily practice.
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Córnea/diagnóstico por imagen , Topografía de la Córnea , Tomografía de Coherencia Óptica , Adulto , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
PURPOSE: To assess visual performance and patient satisfaction of multifocal contact lenses in eyes having monofocal intraocular lens (IOL) implantation. METHODS: We prospectively assessed uncorrected visual acuity at all distances (0.3, 0.4, 0.5, 0.7, 1, and 5 m), higher-order aberrations (HOAs), objective scattering index (OSI), contrast sensitivity, and patient satisfaction, before and during multifocal contact lenses wear in IOL-implanted eyes. RESULTS: Visual acuity at 0.3, 0.4, 0.5, 0.7, 1, and 5 m during wearing multifocal contact lenses was 0.21 ± 0.08, 0.11 ± 0.06, 0.01 ± 0.08, -0.02 ± 0.10, -0.02 ± 0.08, and -0.01 ± 0.07, respectively. We found a significant improvement at near to intermediate distances (30, 40, and 50 cm), but no significant change at intermediate to far distances (70 cm, 1 m, and 5 m). Log contrast sensitivity significantly decreased at 6 and 12 cycles/degrees, but did not significantly change at 1.5, 3, and 18 cycles/degrees. Third-order aberrations significantly increased after CL treatment, but fourth-order aberrations or total higher-order aberrations did not significantly change during CL treatment. The OSI and log(s) did not significantly change during CL treatment. The patient satisfaction score for overall vision significantly improved during CL treatment. CONCLUSIONS: Multifocal contact lenses significantly improved visual acuity at near to intermediate distances, and subsequent patient satisfaction, even though contrast sensitivity function slightly decreased, suggesting its viability of presbyopic correction in monofocal IOL-implanted eyes.
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Lentes de Contacto , Implantación de Lentes Intraoculares/métodos , Lentes Intraoculares , Satisfacción del Paciente , Errores de Refracción/terapia , Agudeza Visual/fisiología , Adulto , Anciano , Sensibilidad de Contraste/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Diseño de Prótesis , Errores de Refracción/fisiopatologíaRESUMEN
PURPOSE: To compare the angle-to-angle (ATA) distance, and the repeatability and the reproducibility of these measurements among the three devices. METHODS: We performed the ATA measurements in 26 healthy subjects using anterior segment optical coherence tomography (CASIA2, Tomey, Japan), the Scheimpflug camera (Pentacam HR, Oculus, Wetzlar, Germany), and the combined Placido-ring corneal topography and Scheimpflug camera (TMS-5, Tomey). We also compared the repeatability and the reproducibility of the ATA measurements among these three devices. RESULTS: The ATA in the CASIA2 group was significantly larger than that in the Pentacam group (Bonferroni test, p = 0.002), or that in the TMS-5 group (p < 0.001). The coefficient variation of the first and second ATA measurements for a single examiner was 0.44% in the CASIA2 group, followed by 0.84% in the TMS-5 group, and 1.92% in the Pentacam group. The coefficient variation of the ATA measurements for two examiners was 0.61% in the CASIA2 group, followed by 0.97% in the TMS-5 group, and 1.84% in the Pentacam group. CONCLUSIONS: The ATA distance measured with the CASIA2 was ~0.40 and 0.56 mm larger than that with the Pentacam and the TMS-5, respectively. The CASIA2 provided the highest repeatability and reproducibility of the ATA measurements, followed by the TMS-5, and the Pentacam. These three instruments cannot be used interchangeably in terms of ATA measurements.
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Córnea , Tomografía de Coherencia Óptica , Topografía de la Córnea , Humanos , Japón , Estudios Prospectivos , Reproducibilidad de los ResultadosRESUMEN
OBJECTIVE: To evaluate the diagnostic accuracy of keratoconus using deep learning of the colour-coded maps measured with the swept-source anterior segment optical coherence tomography (AS-OCT). DESIGN: A diagnostic accuracy study. SETTING: A single-centre study. PARTICIPANTS: A total of 304 keratoconic eyes (grade 1 (108 eyes), 2 (75 eyes), 3 (42 eyes) and 4 (79 eyes)) according to the Amsler-Krumeich classification, and 239 age-matched healthy eyes. MAIN OUTCOME MEASURES: The diagnostic accuracy of keratoconus using deep learning of six colour-coded maps (anterior elevation, anterior curvature, posterior elevation, posterior curvature, total refractive power and pachymetry map). RESULTS: Deep learning of the arithmetical mean output data of these six maps showed an accuracy of 0.991 in discriminating between normal and keratoconic eyes. For single map analysis, posterior elevation map (0.993) showed the highest accuracy, followed by posterior curvature map (0.991), anterior elevation map (0.983), corneal pachymetry map (0.982), total refractive power map (0.978) and anterior curvature map (0.976), in discriminating between normal and keratoconic eyes. This deep learning also showed an accuracy of 0.874 in classifying the stage of the disease. Posterior curvature map (0.869) showed the highest accuracy, followed by corneal pachymetry map (0.845), anterior curvature map (0.836), total refractive power map (0.836), posterior elevation map (0.829) and anterior elevation map (0.820), in classifying the stage. CONCLUSIONS: Deep learning using the colour-coded maps obtained by the AS-OCT effectively discriminates keratoconus from normal corneas, and furthermore classifies the grade of the disease. It is suggested that this will become an aid for improving the diagnostic accuracy of keratoconus in daily practice. CLINICAL TRIAL REGISTRATION NUMBER: 000034587.
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Aprendizaje Profundo , Queratocono/clasificación , Tomografía de Coherencia Óptica/métodos , Estudios de Casos y Controles , Progresión de la Enfermedad , Humanos , Estudios Retrospectivos , Sensibilidad y EspecificidadRESUMEN
Target size and test distance effects on stereoacuity were investigated in 24 subjects using a three-dimensional monitor. Examination 1: Target Size Effects. The test distance was 2.5 m for 0.1°, 0.2°, 0.5°, and 0.9° target sizes; crossed parallax was presented in 22-second units. Average stereoacuity values for 0.1°, 0.2°, 0.5°, and 0.9° target sizes were 59.58 ± 14.86, 47.66 ± 13.71, 41.25 ± 15.95, and 39.41 ± 15.52 seconds, respectively. Stereoacuity was significantly worse with a 0.1° target than with 0.2°, 0.5°, and 0.9° target sizes (P = 0.03, P < 0.0001, and P < 0.0001, resp.). Examination 2: Test Distance Effects. Test distances of 2.5, 5.0, and 7.5 m were investigated for a 0.5° target size; crossed parallax was presented in 22-second units. Average stereoacuity values at 2.5 m, 5.0 m, and 7.5 m test distances were 44.91 ± 16.16, 34.83 ± 10.84, and 24.75 ± 7.27 seconds, respectively. Stereoacuity at a 7.5 m distance was significantly better than at distances of 2.5 m and 5.0 m (P < 0.0001 and P = 0.02, resp.). Stereoacuity at a 5.0 m distance was significantly better than at 2.5 m (P = 0.04). Stereoacuity should be estimated by both parallax and other elements, including test distance and target size.
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PURPOSE: To investigate the repeatability and reproducibility of intraocular pressure (IOP) and central corneal thickness (CCT) measurements using a noncontact tono/pachymeter (NT-530P) and to assess the correlation of CCT with IOP. METHODS: Forty-six eyes of healthy volunteers were measured by two examiners. Three consecutive measurements per eye were performed. Repeatability was assessed using the coefficient of variation, and reproducibility was assessed using Bland-Altman plots. Linear correlations were used to determine agreement between CCT and noncorrected IOP and CCT and corrected IOP, which was calculated using a formula built into the NT-530P. RESULTS: The coefficient of variation for IOP was 6.4% and for CCT was 0.4%. The 95% limits of agreement between examiners were -0.17 ± 1.42 mmHg (range: -2.95 to 2.61 mmHg) for IOP, -0.93 ± 4.37 µ m (range: -9.50 to 7.64 µm) for CCT. The corrected IOP was significantly higher than the noncorrected IOP (P = 0.010.3). The noncorrected IOP significantly correlated with CCT (r = -0.4883, P = 0.0006). The corrected IOP showed no significant correlation with CCT (r = -0.0285, P = 0.8509). CONCLUSIONS: NT-530P offered repeatability and reproducibility in both IOP and CCT measurements. The corrected IOP calculated using the NT-530P was independent of the CCT, suggesting that this IOP may be less influenced by the central corneal thickness.
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Paquimetría Corneal/métodos , Presión Intraocular , Tonometría Ocular/instrumentación , Adulto , Humanos , Persona de Mediana Edad , Reproducibilidad de los Resultados , Estadística como AsuntoRESUMEN
PURPOSE: To investigate the intraocular pressure (IOP) and corneal biomechanical properties of normal and normal-tension glaucoma (NTG) eyes. METHODS: This study included 83 normal and 83 NTG eyes. We measured corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), corneal resistance factor (CRF), corneal hysteresis (CH) and central corneal thickness (CCT) three times each for normal and NTG eyes using an Ocular Response Analyzer (ORA). RESULTS: No significant difference in CCT was seen between normal eyes (541.4 ± 26.8 µm) and NTG eyes (535.4 ± 24.9 µm; p = 0.16). IOPcc was significantly higher in NTG eyes (16.1 ± 2.6 mmHg) than in normal eyes (15.1 ± 2.9 mmHg; p = 0.01), while IOPg was significantly lower in NTG eyes (14.1 ± 2.7 mmHg) than in normal eyes (15.1 ± 3.0 mmHg; p = 0.04). CRF and CH were significantly lower in NTG eyes (CRF, 8.9 ± 1.5 mmHg; CH, 9.2 ± 1.3 mmHg) than in normal eyes (CRF, 10.6 ± 1.4 mmHg; CH, 10.8 ± 1.3 mmHg; p < 0.0001 each). CONCLUSION: IOPcc was significantly higher in NTG eyes than in normal eyes. The ORA may be useful for distinguishing between the IOPcc of NTG eyes with normal IOP and that of normal eyes. In addition, the ORA enables CRF and CH to be measured in vivo, and weakness of the lamina cribrosa may be clinically inferred from the fact that CRF and CH were reduced in NTG eyes in our study. Low CRF and CH may be clues to the pathology of NTG.
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Córnea/fisiología , Elasticidad/fisiología , Glaucoma de Baja Tensión/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos/fisiología , Femenino , Humanos , Presión Intraocular/fisiología , Masculino , Persona de Mediana Edad , Refracción Ocular/fisiología , Tonometría Ocular , Agudeza Visual/fisiología , Campos Visuales/fisiologíaRESUMEN
BACKGROUND: To investigate intraocular pressure (IOP) measurement values in normal tension glaucoma (NTG) eyes using two different types of tonometer that are supposed to be little affected by corneal biochemical properties. METHODS: This study included 30 normal eyes of 16 healthy subjects and 30 eyes of 16 patients with NTG. IOP was measured with a Goldmann applanation tonometer (GAT), a Pascal dynamic contour tonometer (DCT), and a Reichert ocular response analyzer (ORA) three times each for normal and NTG eyes. The main measures were GAT-IOP, DCT-IOP, corneal-compensated IOP (IOPcc), Goldmann-correlated IOP (IOPg), and central corneal thickness (CCT). RESULTS: In normal eyes, GAT-IOP was 13.2 +/- 1.4 mmHg; DCT-IOP, 13.0 +/- 1.6 mmHg; IOPcc, 13.6 +/- 2.0 mmHg; and IOPg, 12.4 +/- 2.0 mmHg. Multivariate analysis revealed no significant differences between the four measurements (p = 0.08). CCT was 524.6 +/- 27.3 microns. In NTG eyes, GAT-IOP was 13.1 +/- 1.3 mmHg; DCT-IOP, 13.7 +/- 1.3 mmHg; IOPcc, 15.2 +/- 2.0 mmHg; and IOPg, 12.7 +/- 2.0 mmHg. Multivariate analysis showed significant differences between the four measurements (p < 0.01). Sheffé's test showed that IOPcc was significantly higher than GAT-IOP, DCT-IOP, and IOPg (GAT-IOP vs IOPcc: p < 0.0001; DCT-IOP vs IOPcc: p = 0.01; IOPcc vs IOPg: p < 0.0001). CCT was 515.4 +/- 32.9 microns, with no significant difference between normal and NTG eyes (p = 0.15). CONCLUSIONS: We investigated the values of IOP in NTG eyes as measured by the DCT and ORA. IOPcc was significantly greater than GAT-IOP, DCT-IOP and IOPg in NTG eyes, suggesting the possibility that IOP values may be underestimated.
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Glaucoma de Ángulo Abierto/fisiopatología , Presión Intraocular/fisiología , Tonometría Ocular/instrumentación , Adulto , Anciano , Córnea/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tonometría Ocular/métodosRESUMEN
PURPOSE: To assess the effect of corneal astigmatism on intraocular pressure (IOP) measurements using an Ocular Response Analyzer (ORA) and a Goldmann applanation tonometer (GAT). METHODS: We prospectively examined 59 normal eyes of 59 healthy volunteers (18 men, 41 women; age, mean +/- standard deviation, 40.5 +/- 14.2 years; age range, 19-68 years). We quantitatively assessed the values of corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOP(G)) using an ORA (Reichert Ophthalmic Instruments). We also measured the IOP using a GAT (GAT-IOP). The amount of corneal astigmatism was assessed with an autokeratometer. We carried out these measurements three times, and the mean value obtained was used for statistical analysis. RESULTS: The mean IOPcc, IOP(G), and GAT-IOP were 14.7 +/- 2.6, 14.0 +/- 2.8, and 14.2 +/- 1.7 mmHg respectively. The mean corneal astigmatism was 0.94 +/- 0.55 D. We found no significant correlation between IOPcc and corneal astigmatism (Pearson's correlation coefficient r = -0.04, p = 0.79), or between IOP(G) and corneal astigmatism (r = 0.09, p = 0.52). However, we found a weak, but significant, correlation between GAT-IOP and corneal astigmatism (Pearson's correlation coefficient r = 0.34, p = 0.009). CONCLUSIONS: Both IOPcc and IOP(G) measured with ORA were less affected by the amount of corneal astigmatism, and the GAT-IOP readings were significantly higher in eyes with greater corneal astigmatism, suggesting that IOPcc as well as IOP(G) may be helpful for accurate IOP measurements in eyes with some corneal astigmatism.
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Astigmatismo/diagnóstico , Enfermedades de la Córnea/diagnóstico , Presión Intraocular , Tonometría Ocular/instrumentación , Tonometría Ocular/métodos , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Índice de Severidad de la Enfermedad , Adulto JovenRESUMEN
BACKGROUND AND OBJECTIVE: This study evaluated the fixation points of macular holes using scanning laser ophthalmoscope microperimetry before and after surgery with internal limiting membrane peeling. PATIENTS AND METHODS: This prospective non-comparative study examined 21 eyes (21 patients) with macular holes. Hole size and distance between preoperative and postoperative fixation points were measured. RESULTS: The fixation points were located on the superior edge of the macular hole in 18 (86%) cases preoperatively and shifted centrally in 15 (71.4%) cases postoperatively. Macular hole size correlated well with the distance moved by the fixation points (r = .83, P < .0001). CONCLUSION: Scanning laser ophthalmoscope microperimetry facilitated pinpointing of fixation points before and after surgery. The correlation between macular hole size and fixation point shift suggests that the retina around the hole moves centripetally after surgery.
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Membrana Basal/cirugía , Fijación Ocular/fisiología , Retina/fisiopatología , Perforaciones de la Retina/cirugía , Vitrectomía , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Oftalmoscopía , Estudios Prospectivos , Perforaciones de la Retina/fisiopatología , Agudeza Visual , Pruebas del Campo Visual/métodosRESUMEN
BACKGROUND: To evaluate factors affecting corneal hysteresis (CH) in normal eyes. METHODS: We examined 86 normal eyes of 43 healthy volunteers (age, 39.1 +/- 14.5 years (mean +/- standard deviation); range, 19 to 68 years; gender, 26 men, 60 women; manifest refraction, -2.25 +/- 2.89 diopters (D); range, -9.13 to 3.88 D). We quantitatively assessed the value of CH using an Ocular Response Analyzertrade mark (Reichert Ophthalmic Instruments). We carried out this measurement three times, and the average value was used for statistical analysis. Multiple regression analysis was used to assess the relevant factors of the CH. RESULTS: The mean CH was 10.2 +/- 1.3 mmHg. Explanatory variables relevant to the CH were, in order of magnitude of influence, the central corneal thickness (CCT) (partial regression coefficient B = 0.022, p < 0.0001), and the intraocular pressure (IOP) (B = -0.119, p = 0.04). No significant correlation was seen with other clinical factors such as age, gender, manifest refraction, or mean keratometric readings. CONCLUSIONS: Eyes with thinner CCT and eyes with higher IOP are more predisposed to have lower CH. Refractive surgeons should, from a biomechanical viewpoint, take not only CCT but also IOP into consideration before performing keratorefractive surgery.