Repeatability of ARK-30 in a pediatric population

Purpose: To determine repeatability and agreement of the ARK-30 handheld autorefractor with retinoscopy under cycloplegic and noncycloplegic conditions in children. Methods: Three consecutive autorefractor measurements (with and without cycloplegia) and retinoscopy were performed and compared in 30 randomized eyes of 30 children (mean age of 6.7 ± 2.7 years with spherical equivalent [SE] refraction from ?4.01 to +7.38 D) in a cross-section and masked study. Bland–Altman analysis of autorefractor measurements (with and without cycloplegia) and agreement with retinoscopy were calculated with conventional notation (sphere [Sph] and cylinder [Cyl]) and vector notation (SE, J0, and J45coefficients). Results: ARK-30 measurements without cycloplegia were lower than under cycloplegic conditions (Sph: ?0.52 ± 2.37 D vs + 0.86 ± 2.60 D, P < 0.01; Cyl: ?0.83 ± 0.80 D versus ?0.78 ± 0.77 D, P = 0.37; and SE: ?0.94 ± 2.19 D vs + 0.47 ± 2.44 D, P < 0.01, respectively) and statistically different (P < 0.03) from retinoscopy (Shp: +0.83 ± 2.66 D; Cyl: ?0.71 ± 0.87 D; SE: +0.51 ± 2.49 D). Without statistical differences were in J0and J45coefficients. Cyloplegic autorefraction measures were not found to be statistically significantly different to retinoscopy measures. ARK-30 under cycloplegia shows better repeatability with lower limits of agreement (LoA) in Sph (LoA: ?0.66 to +0.69 D), and SE (LoA: ?0.66 to +0.65 D) than without cycloplegia (LoA: ?1.45 to +1.77 D, and ?1.38 to +1.74 D, respectively). Conclusion: Under noncycloplegic conditions, ARK-30 autorefractor has low repeatability and a tendency toward minus over correction in children. However, repeatability and agreement with retinoscopy under cycloplegic conditions allow use of ARK-30 in children to estimate refraction but not to substitute gold standard retinoscopic refraction.

Comparison of Manifest Refraction and Cycloplegic Refraction Using Retinoscopy or an Autorefractor in Children

PURPOSE: To compare the measurements between manifest refraction and cycloplegic refraction using retinoscopy or an autorefractor in children and to investigate factors affecting the difference. METHODS: A total of 388 children with a mean age of 7.4 ± 3.6 years were examined using retinoscopy and a Grand Seiko GR-3500KA autorefractor before and after cycloplegia. We compared the difference in spherical and cylindrical components between refractions and analyzed the results according to gender, age, type of refractive error, amblyopia, strabismus, and neuro-developmental disorder. A difference in refractions of ±0.50 D or more was considered as a significant discrepancy. RESULTS: Before cycloplegia, the spherical portion of the refractive error via autorefractor measurement was more myopic than for the retinoscopic measurement in 47.2% of patients, and the cylindrical portion was greater in 37.1%. The spherical discrepancies were more common in children aged < 7 years, with hyperopia, or amblyopia (respectively, p = 0.002, p < 0.001, and p = 0.033). After cycloplegia, the spherical component of the refractive error by auto-refraction differed from retinoscopic measurement in 29.4% of patients, and the cylindrical portion differed in 30.7%. However, the difference was not significant and there was no difference according to clinical features. More than half of the children with discrepancies in the spherical component between retinoscopic refractions before and after cycloplegia had a discrepancy between auto-refraction and retinoscopic refraction before cycloplegia, and the two discrepancies had a significant correlation. CONCLUSIONS: Auto-refraction after cycloplegia can estimate retinoscopic values partially. Nevertheless, 30% of the children still showed a discrepancy. The discrepancy of manifest refraction or auto-refraction compared to retinoscopic refraction with cycloplegia should be considered in younger children, cases with hyperopia or amblyopia, and cases with a difference in auto-refraction and retinoscopic refraction before cycloplegia.

Intra-operative autorefraction for intraocular lens power calculation in cataract surgery.

Objective: To evaluate the correlation between the refractive state of an aphakic eye after phacoemulsification and the appropriate intraocular lens (IOL) power for emmetropia. Methods: This was a prospective, noncomparative consecutive case series study conducted in the Department of Ophthalmology, Ramathibodi Hospital, Bangkok, Thailand. A total of 57 patients underwent phacoemulsification with foldable IOL implantation by a single surgeon. The intra-operative autorefraction was performed by another assisting surgeon prior to IOL implantation. The implanted IOL power and 1-month post-operative spherical equivalent (SE) were used to retrospectively calculate the predicted IOL power for emmetropia. The correlation between intra-operative aphakic SE and the predicted IOL power for emmetropia was evaluated. Results: Fifty seven patients with a mean age of 67.53 years (SD = 7.52) were included in the study. A linear relationship between intra-operative aphakic SE and predicted IOL power achieving plano was found with a formula: predicted IOL power (Diopter; D) = 9.416 + 1.107 (intra-operative aphakic SE), when the intra-operative aphakic SE range was + 7.25 to +16.25 D, with A-constant of 118.7. Conclusion: There is a linear relationship between intra-operative aphakic SE and predicted IOL power. Intra-operative autorefraction may be a simple and reliable method for IOL power calculation in cataract surgery.

Clinical Comparison of Autorefractor versus Retinoscopic Refraction in Children according to the Age

PURPOSE: We analyzed the difference in values between noncycloplegic and cycloplegic autorefraction and refraction, as measured by ophthalmologist, in children according to age. METHODS: We classified the 84 children (153 eyes) whose best corrected visual acuity was better than 0.6 into four groups according to age. The first age group ranged from 29 to 57 months (36 eyes); the second age group ranged from 58 to 75 months (47 eyes); the third age group ranged from 76 to 95 months (36 eyes); and the fourth age group ranged from 96 to 121 months (34 eyes). The children were examined with an autorefractometer (Canon Auto Ref RK-2) and a retinoscope before and after cycloplegia. RESULTS: The children in all age groups tend to show more myopia in autorefraction than refraction regardless of cycloplegia. Also, differences in spherical component and spherical equivalents in noncycloplegic autorefraction and cycloplegic refraction were regarded as significant statistically (P<0.05) in all age groups. However, in all groups, none of the refractive values in cycloplegic autorefraction and refraction were statistically significant. CONCLUSION: Refraction measurement should be recommended for cycloplegic refraction in children. It is suggested that cycloplegic autorefraction could be useful for the refraction partially.

Comparison of Autorefraction and Clinical Refraction with or without in Children

PURPOSE: The difference in the values between autorefraction and clinical refraction with or without cycloplegia in children were analyzed as a function of age. METHODS: One hundred and twenty five children (230 eyes) with myopia or hyperopia were classified into three age groups. Their ages ranged from 2 to 14. They were examined with a Cannon RK-5 autorefractor, and experienced personnel the clinical refraction before and after cycloplegia. Discrepancies beyond 0.5 diopter in spherical equivalent, spherical and cylinder power were regarded as being significant and the discrepancy rates (%) were calculated. The mean absolute differences in the values of each refractive component in myopia and hyperopia were also compared separately according to. RESULTS: All the differences by cycloplegia were significantly smaller in the myopia patients over 5 years old. However, only the discrepancy rates of the spherical equivalent and the sphere component between the clinical manifest refraction and the cycloplegic refraction were significantly smaller in the higher age groups. The comparisons between the clinical and autorefraction revealed significant difference between the age groups only in those with myopia with cycloplegia. CONCLUSIONS: There were differences between the cycloplegic refraction and non-cycloplegic refraction values particularly in myopia patients under five years old and in all hyperopic patients. Autorefraction showed differences from the clinical refraction in both myopia and hyperopia regardless of their ages particularly in those without cycloplegia. Therefore, autorefraction and clinical refraction should be used with caution in children.

Refraction before and after LASIK

PURPOSE: It is important to know the accurate refractive error of the patients before LASIK because the amount of ablation is determined by that. We analyzed whether there are differences among the preoperative and postoperative results of cycloplegic retinoscopy (CR), module setting value, and autorefraction with and without cycloplegia (ACR, AMR). METHODS: The manifest and cycloplegic refractions of 104 eyes of 104 patients who underwent LASIK from February 2001 to July 2001 were reviewed. The preoperative and postoperative cycloplegic refraction, autorefraction by Canon RK-5, and module setting value were analyzed. RESULTS: In comparison of the preoperative values, AMR showed myopic shift compared to CR, module setting, and ACR (p<.001). ACR showed hyperopic shift compared to CR (p<0.001). The module setting showed myopic shift compared to CR, but it was not statistically significant. Postoperative mean spherical equivalent was 0.04 +/- 0.67D(range: -1.75 ~ +1.5). In comparison of the postoperative results, ACR showed hyperopic shift compared to CR (p<0.001) and AMR showed myopic shift compared to CR (p<0.001). CONCLUSIONS: As there is a difference between autorefraction and cycloplegic refraction, it is inappropriate to decide the amount of ablation only by one method. Hence when LASIK or LASIK retreatment is planned, cycloplegic refraction as well as autorefraction is necessary.

Comparison of Refractive Errors Measured by Several Different Methods

PURPOSE: Preoperative measurement of refractive error before LASIK or PRK is very important for good postoperative result because the measured refractive error is the basis of correction amount of operation. We analyzed the difference in spherical equivalent values of manifest refraction by operator (OMR), manifest and cycloplegic refraction by resident (RMR and RCR), noncycloplegic automated refraction (AMR). METHODS: The randomized charts of 50 patients (100 eyes) who had undergone LASIK or PRK for myopia at the Department of Ophthalmology at Samsung Medical Center between May 2000 and November 2000 were reviewed retrospectively and spherical equivalent values of preoperative OMR, RMR, RCR, and AMR by Nikon NRK-8000 autorefractor were analyzed by paired T-test. RESULTS: The mean spherical equivalent values of OMR, RMR, RCR, AMR were -5.40+/-2.10 D, -5.47+/-2.23 D, -5.36+/-2.18 D, -6.25+/-2.24 D, respectively. The spherical equivalent value of AMR was more myopic than the values of others and the bias was statistically significant. The absolute difference of spherical equivalent diopter between OMR and RMR was 0.27+/-0.27 D and that between OMR and RCR was 0.30+/-0.33 D. These two absolute difference did not show statistical significance. CONCLUSIONS: This study revealed that there was statistically significant difference in spherical equivalent diopter measured by AMR compared to those measured by OMR, RMR, or RCR. So we recommend the method of manifest and cycloplegic refraction by two ophthalmologists before LASIK or PRK for accurate measurement of refractive error.

The Evaluation of Noncycloplegic and Cycloplegic Autorefraction in Children According to the Age

We analysed the difference of values between noncycloplegic and cycloplegic autorefractionand refraction by ophthalmologist in children. We classified the 109 children [218 eyes] who did not have strabismus or amblyopia into five groups according to the age. Their age ranged from 3 to 12. They were examined with Canon RK-3 autorefractor before and after cycloplegia and then, cycloplegic and post-cycloplegic refraction were performed by ophthalmologist. Discrepancies beyond 0.5D in spherical and cylindrical power and 10 degree in cylindrical axis were regarded as significant. The percentages of discrepancy were greater in spherical power between noncycloplegic autorefraction and refraction by ophthalmologist especially in young age groups[p<0.05]. The percentages of discrepancy were greater in spherical and cylindrical power between cycloplegic autorefraction and refraction by ophthalmologist especially in young age groups[p<0.05]. The percentages of discrepancy of cycloplegic autorefraction showed a tendency to be greater than those of noncycloplegic autorefraction in spherical power as compared with refraction by ophthalmologist. In conclusion, the refractive measurements of cycloplegic autorefractor is not close to those of refraction by ophthalmologist in children. The refraction by ophthalmologist must be recommended for correction of refractive errors in children.