Accuracy and precision of automated subjective refraction in young hyperopes under cycloplegia

Purpose: To assess the agreement between the Eye Refract, an instrument to perform subjective automated refraction, and the traditional subjective refraction, as the gold standard, in young hyperopes under noncycloplegic and cycloplegic conditions. Methods: A cross-section and randomized study was carried out, involving 42 participants (18.2 ± 7.7 years, range 6 to 31 years). Only one eye was chosen for the analysis, randomly. An optometrist conducted the refraction with the Eye Refract, while another different optometrist conducted the traditional subjective refraction. Spherical equivalent (M), cylindrical components (J0 and J45), and corrected distance visual acuity (CDVA) were compared between both refraction methods under noncycloplegic and cycloplegic conditions. A Bland-Altman analysis was performed to assess the agreement (accuracy and precision) between both refraction methods. Results: Without cycloplegia, the Eye Refract showed significantly lower values of hyperopia than the traditional subjective refraction (p < 0.009), the mean difference (accuracy) and its 95% limits of agreement (precision) being -0.31 (+0.85, -1.47) D. Conversely, there were no statistical differences between both refraction methods under cycloplegic conditions (p ≥ 0.05). Regarding J0 and J45, both refraction methods manifested no significant differences between them under noncycloplegic and cycloplegic conditions (p ≥ 0.05). Finally, the Eye Refract significantly improved CDVA (0.04 ± 0.01 logMAR) compared with the traditional subjective refraction without cycloplegia (p = 0.01). Conclusions: The Eye Refract is presented as a useful instrument to determine the refractive error in young hyperopes, the use of cycloplegia being necessary to obtain accurate and precise spherical refraction. (AU)

Accuracy of an objective binocular automated phoropter for providing spectacle prescriptions.

CLINICAL RELEVANCE: Currently eye examinations are usually based on autorefraction followed by subjective refraction (SR) with a phoropter. An automated phoropter that can also perform autorefraction may facilitate the optometric workflow. BACKGROUND: The efficiency and feasibility of an objective autorefraction and correction system are assessed by comparing objective refractive measurements with SR on the same subjects and evaluating the visual acuity (VA) values obtained after the objective refractive measurement and correction. METHODS: Objective autorefraction and correction was performed on 41 subjects using an automated binocular phoropter system. The auto-phoropter performs autorefraction by wavefront measurement and corrects the spherical and cylindrical errors with tunable fluidic lenses while the patient looks at a visual display inside the instrument. The instrument outputs are optometric constants of spherical and cylindrical aberrations. After measurement and automated correction of the refractive errors, the VA values were assessed by having the subjects look at an integrated Snellen chart. The objective measurement results were statistically compared with their SR. RESULTS: The correlations between SR and objective autorefraction and correction spherical equivalents (M) were 0.98 (0.97-0.99) and 0.96 (0.93-0.98), the vertical Jackson cross cylinder (J0) were 0.96 (0.92-0.98) and 0.95 (0.91-0.97), and the oblique Jackson cross cylinder (J45) were 0.73 (0.55-0.85) and 0.82 (0.69-0.90), for the right and left eyes, respectively, with the 95% confidence interval (CI) values in parentheses. 89.0% of the 82 eyes had at least 6/7.5 VA. CONCLUSIONS: A significant agreement between the SR and objective autorefraction and correction was observed. An all-objective refractive assessment with instantaneous verification may improve the precision of eye prescriptions and possibly reduce the procedure time.

Accuracy and precision of automated subjective refraction in young hyperopes under cycloplegia.

PURPOSE: To assess the agreement between the Eye Refract, an instrument to perform subjective automated refraction, and the traditional subjective refraction, as the gold standard, in young hyperopes under noncycloplegic and cycloplegic conditions. METHODS: A cross-section and randomized study was carried out, involving 42 participants (18.2 ± 7.7 years, range 6 to 31 years). Only one eye was chosen for the analysis, randomly. An optometrist conducted the refraction with the Eye Refract, while another different optometrist conducted the traditional subjective refraction. Spherical equivalent (M), cylindrical components (J0 and J45), and corrected distance visual acuity (CDVA) were compared between both refraction methods under noncycloplegic and cycloplegic conditions. A Bland-Altman analysis was performed to assess the agreement (accuracy and precision) between both refraction methods. RESULTS: Without cycloplegia, the Eye Refract showed significantly lower values of hyperopia than the traditional subjective refraction (p < 0.009), the mean difference (accuracy) and its 95% limits of agreement (precision) being -0.31 (+0.85, -1.47) D. Conversely, there were no statistical differences between both refraction methods under cycloplegic conditions (p ≥ 0.05). Regarding J0 and J45, both refraction methods manifested no significant differences between them under noncycloplegic and cycloplegic conditions (p ≥ 0.05). Finally, the Eye Refract significantly improved CDVA (0.04 ± 0.01 logMAR) compared with the traditional subjective refraction without cycloplegia (p = 0.01). CONCLUSIONS: The Eye Refract is presented as a useful instrument to determine the refractive error in young hyperopes, the use of cycloplegia being necessary to obtain accurate and precise spherical refraction.

COMPARISON OF SMARTPHONE-BASED AND AUTOMATED REFRACTION WITH SUBJECTIVE REFRACTION FOR SCREENING OF REFRACTIVE ERRORS.

PURPOSE: To compare Netra smartphone-based and automated refraction with subjective refraction for screening of refractive errors. METHODS: Cross-sectional study at the University of Malaya Medical Centre, Kuala Lumpur. Subjects underwent subjective refraction, then automated refraction, and finally Netra smartphone-based refraction. All results were converted to power vectors (M, J0 and J45) and were analysed using repeated-measures ANOVA and Bland-Altman plots. Sensitivity and specificity were determined. The best cut-off points were determined from ROC curve analysis. P < .05 was considered statistically significant. RESULTS: Data from the right eyes of 204 subjects were analysed. Mean age was 36.6 ± 15.7 years (range 16-78 years). Spherical equivalent [mean (95% CI)] from Netra and automated refraction were similar, and both more myopic than subjective refraction; -2.87 (-3.23 to -2.51), -2.85 (-3.21 to -2.49) and -2.46 (-2.83 to -2.10) respectively (p < .001). Differences in J0 and J45 between Netra and subjective refraction were not statistically significant (0.10 vs 0.11 and 0.01 vs -0.02 respectively, both p > .05), but those between automated and subjective refraction were (0.06 vs 0.11 and 0.07 vs -0.02, p = .004 and p < .001 respectively). Bland Altman plots showed the 95% limits of agreement with Netra refraction were wider than with automated refraction (-2.21D to 1.42D vs. -1.90D to 1.16D respectively). CONCLUSION: Netra smartphone-based refraction gives similar readings to automated refraction, and both show myopic overestimation when compared to subjective refraction. However, due to non-insignificant practical usage issues, its use as a screening tool for refractive errors is limited.

Stabilisation of Automated Refraction in the Immediate Time After Uneventful Cataract Surgery.

INTRODUCTION: To determine which day automated refraction stabilised the first week after uneventful cataract surgery. METHODS: This was a prospective, single-blinded, randomised cohort study of 148 eyes in 148 consecutive patients undergoing uneventful cataract surgery. Automated refraction was measured from days 2 to 7 after surgery and compared to automated refraction measured 6 weeks post-surgery. We compared measurements using a hierarchical mixed-effect model. RESULTS: Our adjusted results did not show a statistically significant change in spherical equivalent between the first week after surgery and 6 weeks after surgery (p-values: day 2: 0.914, day 3: 0.922, day 4: 0.168, day 5: 0.211, day 6: 0.457, day 7: 0.621). We measured the spherical error as stable except for day 5, where a statistically significant change of 0.32 dioptre (p = 0.049) was detected. Similarly, the cylindrical error was also stable on all days of measurements except on day 6, where a significant change of 0.28 dioptre (p = 0.034) was detected. CONCLUSION: The adjusted spherical equivalent was stable on days 2-7 after uneventful cataract surgery in our study population. However, as we observed a statistically significant difference in spherical and cylindrical errors on days 5 and 6, respectively, we could not conclude that automated refraction stabilised the first week after uncomplicated cataract surgery.

Automated refraction is stable 1 week after uncomplicated cataract surgery.

PURPOSE: To compare automated refraction 1 week and 1 month after uncomplicated cataract surgery. METHODS: In this prospective cohort study, we recruited patients in a 2-month period and included consecutive patients scheduled for bilateral small-incision phacoemulsification cataract surgery. The exclusion criteria were (i) corneal and/or retinal pathology that could lead to automated refraction miscalculation and (ii) surgery complications. Automated refraction was measured 1 week and 1 month after surgery. RESULTS: Ninety-five patients met the in- and exclusion criteria and completed follow-up. The mean refractive shift in spherical equivalent was -0.02 dioptre (D) between 1 week and 1 month after surgery and not statistical significant (p = 0.78, paired t-test). The magnitude of refractive shift in either myopic or hyperopic direction was neither correlated to age, preoperative corneal astigmatism, axial length nor phacoemulsification energy used during surgery (p > 0.05 for all variables, regression analysis). The refractive target was missed with 1.0 D or more in 11 (12%) patients. In this subgroup, the mean refractive shift in spherical equivalent was 0.49 D between 1 week and 1 month after surgery with a trend towards statistical significance (p = 0.07, paired t-test). There was no difference in age, preoperative corneal astigmatism, axial length or phacoemulsification energy used during surgery compared to the remainder of the patients (p > 0.05 for all variables, unpaired t-test). CONCLUSION: Automated refraction is stabile 1 week after uncomplicated cataract surgery, but there is a trend towards instability, if the refractive target is missed with 1.0 D or more.

The Stabilization Time of Ocular Measurements after Cataract Surgery.

PURPOSE: To determine the stabilization time of automated refraction, ocular biometric parameters, keratometry, and central corneal thickness (CCT) and to find the optimal time for glasses' prescription after cataract surgery. METHODS: This was a prospective, case series study of 62 consecutive eyes with senile cataracts. Patients undergoing uncomplicated phacoemulsification surgery were included in the study. Automated refraction, keratometry, ocular biometric parameters, and CCT were recorded at baseline before cataract surgery and at follow-up visits at one day, one week, two weeks, and four weeks after surgery. RESULTS: The study was composed of 62 eyes of 62 patients with a mean age of 66±12.38 (range, 40 to 84 years). The automated refraction stabilized one week after surgery and changed minimally between the first week and the first month after cataract surgery. The stabilization of average keratometric corneal astigmatism in keratometry, average anterior chamber depth, and CCT was achieved after the second postsurgical week. CONCLUSION: It may be possible to prescribe glasses starting from two weeks after an uneventful phacoemulsification cataract surgery for most patients.

Difference of the Accuracy between Autorefration and Subjective Refraction in Photorefractive Keratectomy(PRK) and LASIK-Treated Eyes

Authors decided to test whether differences occurred in automated and subjective refraction in untreated, PRK, and LASIK-treated eyes. Ninety six eyes of 50 patients(96 eyes) who underwent PRK(57 eyes) or LASIK(39 eyes) for myopia and myopic astigmatism were routinely autorefracted with the CANON RK-3 before subjective refraction was done, using several parameters. This two procedures were done preoperation and 3 months after operation. In comparing the postoperative(PRK, LASIK) results, automated refraction showed more myopia and higher cylinder power, without significant difference in refractive axis, than those of subjective measurement. The difference of cylinder power were found in the cases of large ablation depth(above 100micrometer), high degree of eccentric ablation(above 0.25 mm), LASIK operation. The significant differences of cylinder power and axis were found in the cases of high degree of eccentric ablation(above 0.25 mm). So we recommend the method of subjective refraction before PRK and LASIK operation instead of using automated refraction. Postoperatvely, we also should evaluate the postoperative status of the patient by subjective refraction. And we should decide the amount of ablation in case of retreatment by subjective refraction, instead of autorefraction. We have to be cautious of evaluating the automated refraction results after operation, especially in cases of large ablation depth, high degree of eccentric ablation, and LASIK.

A Study about the Accuracy of Automated Refraction

We analysed the differences between the values of noncycloplegicautomated refraction and manifest refraction by ophthalmologist 150 patients(274 eyes)were studied. We divided these patients into five groups according to the age; Group 1 included patients under 10 yea(n=50 eyes), Group 2 from 10 yrs to 19 yrs(n=74 eyes), Group 3 from 20 yrs to 39 yrs(n=66 eyes), Group 4 from 40 yrs to 49yrs(n=39 eyes), Group 5 over 50 yrs(n=46 eyes); We used Canon Auto Ref R-10 autorefractor and ophthalmologist's refractions were the results of both subjective refraction by retinoscope and objective refraction used by cross cylinder. Between the two examinations, the percentages of eyes of disagreement beyond +/-0.5D were 22%(group 1), 39.2%(group 2), 14.1%(group 3), 15.8%(group 4), 17.4%(group 5) in spherical power; 18%, 23%, 27.3%, 29%, 15.2% in cylindrical power respectively; 20%, 31.9%, 18.2%, 15.8%, 19.6% in spherical equivalent respectively and the percentages of eyes of disagreement beyond +/-10 degrees in cylindrical axis were 25%, 42.6%, 39.2%, 40%, 52.9% respectively. There was no statistic significance between the age groups when we compared the absolute differences of values between two examinations. Conclusively, this study revealed that there were large differences between the values of noncycloplegic automated refraction and manifest refraction by ophthalmologist in the large amout of patients and then our results indicated that automated refraction was dangerous to patient's eyes and subjective refinement was needed by ophthalmologist if patients wanted the spectacle or contact lens.