Rigid contact lenses with eccentricity through manufacture can more or less influence visual correction or induce the corneal warpage. Therefore the fine detection of rigid contact lens eccentricity is needed and important. This study was aimed to design a system for lens eccentricity measurement by the principle of optical reflection. By using a standard concave mirror in the center of lens jig, the geometrical center of a lens could be detected accurately. It has solved the problem of lens distortion and breakableness attributed to the conventional method based on rotating reflection. The system is proved to be of practical method with good repeatability.
Contact Lenses ; adverse effects ; Cornea ; pathology ; Refraction, Ocular ; physiology ; Refractive Errors ; pathology

BACKGROUNDOptical Quality Analysis System II (OQAS, Visiometrics, Terrassa, Spain) that uses double-pass (DP) technique is the only commercially available device that allows objective measurement of ocular retinal image quality. This study aimed to evaluate the impact of spectacle lenses on the ocular optical quality parameters and the validity of the optometer within OQAS.

METHODSSeventy eyes of healthy volunteers were enrolled. Optical quality measurements were performed using OQAS with an artificial pupil diameter of 4.0 mm. Three consecutive measurements were obtained from spectacle correction corresponding to subjective refraction and from the OQAS built-in optometer separately. The modulation transfer function cutoff frequency, the Strehl ratio, the width of the point spread function (PSF) at 10% of its maximal height (PSF10), and the width of the PSF at 50% of its maximal height (PSF50) were analyzed.

RESULTSThere was no significant difference in any of the parameters between the spectacle correction and the optometer correction (all P > 0.05, paired t-test). A good agreement was found between both the methods and a good intraobserver repeatability in both the correction methods. Difference in best focus between two methods was the only parameter associated significantly with optical quality parameter differences. Best focus difference, built-in optometer correction with or without external cylindrical lens, and age were associated significantly with PSF10 difference. No linear correlation between refractive status and optical quality measurement difference was observed. A hyperopic bias (best focus difference of (0.50 ± 0.44) D) and a relatively better optical quality using spectacle correction in high myopia group were found.

CONCLUSIONSOQAS based on DP system is a clinically reliable instrument. In patients with high myopia, measurements using built-in optometer correction should be considered and interpreted with caution.

Adolescent ; Adult ; Aged ; Female ; Humans ; Male ; Middle Aged ; Refraction, Ocular ; Visual Acuity ; physiology ; Young Adult

Higher order aberrations (HOAs) were measured in 54 anisometropic amblyopic children using the ZY-WAVE II aberrometer. The results were compared in normal fellow and amblyoic eyes which were determined by the corrected visual acuity. Between the normal eyes and anisometropic amblyopic eyes, no statistically significant difference were found in mean root square of total HOAs, total coma (TC), total spherical aberration (TSA), and the 5th root mean square (RMS5). There was no correlation among best corrected visual acuity (BCVA), HOAs, TC, TSA, and RMS5. There was some positively correlation between the degree of anisometropia and TC. HOAs increase with the increasing of the degree of anisometropic amblyopia. Lower order aberrations are the main refractive factors leading to amblyopia, and HOAs is related to anisometropia amblyopia. The study helps us understand the mechanism of amblyopia and make the further study.
Aberrometry ; Adolescent ; Amblyopia ; diagnosis ; physiopathology ; Child ; Corneal Wavefront Aberration ; physiopathology ; Female ; Humans ; Male ; Refraction, Ocular ; physiology ; Visual Acuity ; physiology

BACKGROUNDAmblyopia is a common ophthalmological condition and the wavefront aberrometer is a relatively new diagnostic tool used globally to measure optical characteristics of human eyes as well as to study refractive errors in amblyopic eyes. We studied the wavefront aberration of the amblyopic children's eyes and analyzed the mechanism of the wavefront aberration in the formation of the amblyopia, try to investigate the new evidence of the treatment of the amblyopia, especially in the refractory amblyopia.

METHODSThe WaveScan Wavefront System (VISX, USA) aberrometer was used to investigate four groups of children under dark accommodation and cilliary muscle paralysis. There were 45 cases in the metropic group, 87 in the amblyopic group, 92 in the corrected-amblyopic group and 38 in the refractory amblyopic group. One-way analysis of variance (ANOVA), t-test and multivariate linear regression were used to analyze all the data.

RESULTSThird order to 6th order aberrations showed a decreasing trend whereas in the higher order aberrations the main ones were 3rd order coma (Z(3)(-1)-Z(3)(1)), trefoil (Z(3)(-3)-Z(3)(3)) and 4th order aberration (Z(4)(0)); and 3rd order coma represented the highest percentage of all three main aberrations. Within 3rd order coma, vertical coma (Z(3)(-1)) accounted for a greater percentage than horizontal coma (Z(3)(1)). Significant differences of vertical coma were found among all clinical groups of children: vertical coma in the amblyopic group (0.17 +/- 0.15) was significantly higher than in the metropic group (0.11 +/- 0.13, P < 0.05). In addition, the vertical coma in the refractory amblyopic group (0.19 +/- 0.15) was higher compared with the metropic group (P < 0.05), the 5th order aberration (0.11 +/- 0.08) was also significantly higher than in the metropic group (0.07 +/- 0.04, P < 0.05). No significant difference was found in vertical coma and 5th order aberration between the corrected-amblyopic group (0.13 +/- 0.11) and metropic group (0.07 +/- 0.04) (P > 0.05).

CONCLUSIONSAlthough lower order aberrations such as defocus (myopia and hyperopia) and astigmatism are major factors determining the quality of the retinal image, higher order aberrations also need to be considered in amblyopic eyes as their effects are significant.

Aberrometry ; Amblyopia ; pathology ; physiopathology ; Child ; Child, Preschool ; Female ; Humans ; Male ; Refraction, Ocular ; physiology ; Refractive Errors ; diagnosis ; pathology

PURPOSE: To evaluate the effect of acrylic refractive prism and Fresnel membrane prism on stereoacuity in intermittent exotropia. MATERIALS AND METHODS: Stereoacuities of fifty-two patients (mean age, 12.4 years; range 6 to 45 years) with intermittent exotropia were measured using the Titmus and TNO stereotests, while they wore prisms of varying power on nonfixating eye or evenly on each eye. RESULTS: Stereoacuities were significantly reduced with increasing prism power for both prisms, ranging from 8 to 25 prism dipotres. The effects on stereoacuity in single acrylic prism and single Fresnel prism were similar, whereas spilt Fresnel prisms reduced stereoacuity more than spilt acrylic prisms. Spilt prisms were found to have much less effect on stereoacuity than single prisms for both acrylic and Fresnel prisms. CONCLUSION: The use of acrylic refractive prism shared evenly on each eye would be optimal method to minimize the reduction of stereoacuity during the prismatic therapy for intermittent exotropia.
Adolescent ; Adult ; Child ; Depth Perception/*physiology ; Exotropia/physiopathology/*therapy ; *Eyeglasses ; Female ; Humans ; Male ; Refraction, Ocular/physiology ; Visual Acuity/*physiology ; Young Adult

PURPOSE: The aim of this study is to investigate the clinical characteristics of patients diagnosed with refractive accommodative esotropia (RAE) whose refractive errors were gradually reduced to below +2.00 diopters (D) during follow-up but use of spectacles was still required for maintenance of good ocular alignment. METHODS: We conducted a retrospective review of the medical records of patients diagnosed with RAE from 1995 to 2011. Patients were divided into 2 groups according to their ocular alignment at the last visit. Inclusion criteria were hyperopia > or =+2.00 D detected with cycloplegic refraction at the initial visit, which then became mild hyperopia (<+2.00 D) or myopia during follow-up, with more than 5 years of follow-up. RESULTS: A total of 92 patients met the inclusion criteria. Twenty-six patients showed persistent esotropia (> or =10 prism diopters [PD]) without spectacles (group A) and 66 patients showed good ocular alignment (<10 PD) without spectacles (group B) at the last visit. No statistically significant differences in the spherical equivalent of the refractive errors at the initial and last visit were observed between the two groups. A significantly lower number of positive responses on the Lang I stereotest was observed in group A (n = 1, 3.8%) compared to group B (n = 22, 33.3%) (p = 0.003). There were increasing trends toward group A with worsening stereoacuity measured by the Stereo Fly Stereotest between the two groups (p = 0.016, linear by linear association). The results of the Lang I test, Stereo Fly Stereotest, and duration between the onset of esotropia and prescribing spectacles showed a significant association with the discontinuation of spectacles in the univariate logistic analysis. CONCLUSIONS: Stereoacuity showed more significant associations than refractive errors in RAE with refractive error <+2.00 D but still required spectacles for maintenance of good ocular alignment. The prompt treatment of accommodative esotropia at the onset of esotropia is important for the discontinuation of spectacles.
Accommodation, Ocular/physiology ; Adult ; Aged ; Esotropia/*physiopathology ; *Eyeglasses ; Female ; Follow-Up Studies ; Humans ; Hyperopia/physiopathology/*therapy ; Male ; Middle Aged ; Refraction, Ocular/physiology ; Retrospective Studies ; Vision, Binocular/*physiology ; Visual Acuity/physiology

OBJECTIVE: To explore the relationship between best corrected visual acuity (BCVA) and refraction parameters in myopia. METHODS: Two thousand two hundred and seventy-four patients (4245 eyes) with different degrees of myopia were collected. Their BCVA, diopter of spherical (DS), diopter of cylinder (DC), astigmatism axis, axial length (AL) and corneal thickness were detected. The influence of those parameters on BCVA was studied and the mathematical model of the relationship between BCVA and other parameters including the age and gender of patients was established. RESULTS: The logistic regression analysis showed that there were correlations between the BCVA (y) and DS (x1), DC (x2), gender (x3), AL (x4), corneal thickness (x5), astigmatism axis (x6) and age (x7) (P<0.05): y=0.580 6-0.034 0 x1-0.046 8 x2+0.056 5 x3+0.016 5 x4+ 0.0007 x5+0.000 2 x6-0.005 8 x7. CONCLUSION For people with myopia, age, gender and corneal thickness have small effect on BCVA, while the DS, DC, AL and astigmatism axis have significant effect on BCVA. The BCVA would decline following the extension of DS, DC and AL. It is helpful to assess the vision of myopia by analyzing the refraction parameters comprehensively.
Adolescent ; Adult ; Child ; Cornea/pathology* ; Female ; Forensic Medicine/methods* ; Humans ; Male ; Middle Aged ; Models, Theoretical ; Myopia/physiopathology* ; Refraction, Ocular/physiology* ; Refractometry ; Visual Acuity ; Visual Fields/physiology* ; Young Adult

PURPOSE: To compare changes of anterior corneal aberration (Pentacam(R)) and ocular aberration (aberrometer, LADARWave(R)) after laser refractive surgery. METHODS: Sixty-six eyes underwent laser refractive surgery and were retrospectively reviewed. Anterior corneal aberration and ocular aberration were measured by Pentacam(R) and an aberrometer (LADARWave(R)) respectively. Changes of root mean square (RMS) values of coma, spherical aberration, and total high order aberration (HOA) were evaluated before, 1 month, and 3 months after surgery RESULTS: Ocular aberrations displayed low preoperative values, but after laser refractive surgery, anterior corneal aberration and ocular aberration increased equally. There were no statistically significant differences of internal optics aberration values (ocular aberration minus anterior corneal aberration) in coma, spherical aberration, and total HOA. Anterior corneal aberration and ocular aberration showed statistically significant correlations at 1 and 3 months after surgery. CONCLUSIONS: Internal optics aberration compensated the anterior corneal aberration effectively before surgery, but the increase of anterior corneal aberration after laser refractive surgery exceeded the compensation of internal optics. As a result, anterior corneal aberration and ocular aberration increased equally. The correlation between anterior corneal aberration and ocular aberration after surgery was statistically significant due to the increased proportion of anterior corneal aberration in ocular aberration.
Adult ; Cornea/*physiopathology ; Corneal Topography ; Humans ; Lasers, Excimer/*therapeutic use ; Myopia/surgery ; Photography ; Refraction, Ocular/*physiology ; Refractive Errors/*physiopathology ; *Refractive Surgical Procedures ; Retrospective Studies

PURPOSE: To determine effectiveness of laser-assisted in situ keratomileusis (LASIK) in the treatment of astigmatism following penetrating keratoplasty (PK). METHODS: We performed a retrospective review of medical records of patients who underwent LASIK following PK and had over 1 year of follow-up data. RESULTS: Twenty-six patients (26 pairs of eyes) underwent LASIK following PK. Mean age of the patients at the time of LASIK was 40.7 years (range, 26 to 72 years). Following LASIK, the mean cylinder was reduced by 2.4 diopters and mean reduction of cylinder after LASIK was 65.4% from the preoperative values at the last follow-up visit. Uncorrected visual acuity became 20 / 50 or better in 69.2% of the eyes after LASIK. Best-corrected visual acuity became 20 / 50 or better in 73.1% of the eyes after LASIK. All of them were intolerable to contact lenses before LASIK. After LASIK, 6 pairs (23.1%) did not need to use contact lenses and 18 pairs (69.2%) were tolerable to using contact lenses or spectacles. There were no significant endothelial cell density changes 12 months after LASIK (p = 0.239). CONCLUSIONS: LASIK is effective in the treatment of astigmatism following PK and increases contact lens and spectacle tolerance.
Adult ; Aged ; Astigmatism/etiology/physiopathology/*surgery ; *Contact Lenses/utilization ; Corneal Topography ; Female ; Humans ; Keratomileusis, Laser In Situ/*methods ; Keratoplasty, Penetrating/*adverse effects ; Lasers, Excimer/*therapeutic use ; Male ; Middle Aged ; Refraction, Ocular/physiology ; Retrospective Studies ; Vision, Binocular/physiology ; Visual Acuity/physiology

PURPOSE: To compare the refractive results of cataract surgery measured by applanation ultrasound and the new partial coherence interferometer, AL-scan. METHODS: Medical records of 76 patients and 104 eyes who underwent cataract surgery from January 2013 to June 2013 were retrospectively reviewed. Biometries were measured using ultrasound and AL-scan and intraocular lens power was calculated using the SRK-T formula. Automatic refraction examination was done 1 month after the operation, and differences between the ultrasound group and AL-scan group were compared and analyzed by mean absolute error. RESULTS: Mean axial length measured preoperatively by the ultrasound method was 23.53 +/- 1.17 mm while the lengths measured using the AL-scan were 0.03 mm longer than that of the ultrasound group (23.56 +/- 1.15 mm). However, there was not a significant difference in this finding (p = 0.638). Mean absolute error was 0.34 +/- 0.27 diopters in the ultrasound group and 0.36 +/- 0.31 diopters in AL-scan group, which showed no significant difference (p = 0.946) in precision of predicting postoperative refraction. CONCLUSIONS: Although the difference was not statistically significant, intraocular lens calculations done by the AL-scan were nearly similar in predicting postoperative refraction compared to those of applanation ultrasound, however more precise measurements may be obtained if the axial length is longer than 24.4 mm. Except in the case of opacity in the media, which makes obtaining measurements with the AL-scan difficult, AL-scan could be a useful biometry in cataract surgery.
Aged ; Anterior Chamber/pathology ; Axial Length, Eye/*pathology ; Biometry/methods ; Female ; Humans ; Interferometry/*instrumentation ; *Lens Implantation, Intraocular ; Lenses, Intraocular ; Light ; Male ; Middle Aged ; *Phacoemulsification ; Refraction, Ocular/physiology ; Reproducibility of Results ; Retrospective Studies ; Visual Acuity/physiology