Utility of retinoscopy to examine peripheral refraction

PURPOSE

This study explored whether retinoscopy (RET) provides comparable results of relative peripheral refraction (RPR) to open-field autorefractometry (AR) in myopic subjects.

METHODS

Peripheral refraction was measured in 20 myopic and 20 control adult subjects. Both central and peripheral refraction (20° nasal and temporal eccentricity) were measured using RET and open-field AR. Differences in the median central spherical equivalent (SE), median RPR, and median J45/J180 power vectors between the RET and AR techniques were analyzed. Moreover, Bland - Altman plots were used to assess the agreement between RET and AR methods for RPR measurements in MG.

RESULTS

For MG, the median RPR values were positive (hyperopic shift), and no significant differences were observed between the RET and AR techniques with respect to RPR measurement. In addition, we did not observe any significant differences in the RPR values between the nasal and temporal eccentricities for either the RET or AR technique for myopic subjects. There was also a significant correlation and agreement between the RET and AR technique for RPR measurements. With respect to central refraction, the median SE was slightly more positive for the RET than for the AR technique. Inside the CG, we also found significant correlation between the RET and AR technique for RPR measurements, and we observed a myopic shift in peripheral eccentricities.

CONCLUSION

Our results show that retinoscopy may be a useful tool for objective measurements of RPR in myopic subjects and may be used interchangeably with the open-field AR method in everyday clinical practice.

Training in retinoscopy: learning curves using a standardized method

BACKGROUND

Retinoscopy is one of the most effective objective techniques for evaluating refractive status, especially in non-cooperative patients. However, it presents a slow learning curve that often leads to student frustration. With the current Covid-19 pandemic and the need for social isolation, clinical education based on simulation has become more relevant. Therefore, we implemented retinoscopy laboratories and learning protocols to reduce student stress and learning time.

METHODS

We conducted a study to evaluate the retinoscopy learning curve using a new training protocol proposal. One hundred trainees were assessed in four stages, corresponding to 08, 12, 16, and 20 hours of training. Six different refractive defects were used trying to reproduce frequent conditions of care. The time spent on the assessment was not considered as additional training time. To analyze the data, we used non-parametric statistics and linear regression to assess the variables associated with training time and performance rate.

RESULTS

The mean performance score at 08 hrs was 32.49% (±16.69 SD); at 12 hrs was 59.75% (±18.80 SD); at 16 hrs was 70.83% (±18.53 SD) and at 20 hrs was 84.26% (±13.18 SD). Performance at 12 hrs was significative higher than 08 hrs of training, but did not show significant differences with the performance rate at 16 and 20 hrs. We found a strong positive correlation between performance and training time in retinoscopy (R = 0.9773, CI: 0.2678 - 0.9995 p = 0.0227).

CONCLUSION

This study showed that an increasing number of hours of practice positively correlates with performance in retinoscopy. The elaboration of a protocol and standardization of performance per hour also allowed us to estimate that a minimum of 13.4 hrs of practice is required to achieve 60% performance. Using the resulting formula, it is possible to determine the number of hours of retinoscopy practice are necessary to reach a certain level of performance.

Correlation and agreement between the Mohindra and cycloplegic retinoscopy techniques in children

PURPOSE

As an objective technique to assess refractive status, retinoscopy is particularly useful in children. The Mohindra technique (RM) is an alternative for those patients not good candidates for cycloplegic retinoscopy (RC). The aim of the present research was to compare both techniques and to determine the correlation and agreement of their measurements.

MATERIAL AND METHODS

A total of 47 boys and girls of ages ranging from 3 to 11 years old were included in the study. Cycloplegic (cyclopentolate 1%) and Mohindra retinoscopy were conducted in both eyes, and refraction was also assessed with an autorefractometre (AR). The results from the three techniques were compared and a correction factor between RM and RC was calculated.

RESULTS

Statistically significant differences were found between RM and RC (median of -0.42 D; p < 0.001) and between RM and AR (median of -0.42 D; p = 0.008), but not between RC and AR (median of 0.00 D; p = 0.758). A strong correlation was found between RM and RC (rho = 0.846; p < 0.001), although the Bland-Altman test revealed a larger difference between these techniques in patients with larger hyperopic refractive errors, with a correction factor of RC = 1.15 RM + 0.42.

CONCLUSIONS

The Mohindra technique may be considered a valid alternative to cycloplegic retinoscopy in patients of young age, with a good correlation between both techniques, albeit less agreement in patients with high hyperopic refractions.

Introducing a new method of retinoscopy for refraction of infants and young children: The "Mirza" tele lens retinoscopy

PURPOSE

This study aimed to evaluate the refractive error of the uncooperative infants and children with the new method of retinoscopy called the tele-lens ("Mirza") retinoscopy.

METHODS

In the "Mirza" tele-lens retinoscopy, the examiner placed the trial lenses in 1/3 distance between the tested eye person and peephole of the retinoscope (22.2 cm far from the spectacle plane). First, the optical calculations were done to find the correction factors for this new method of retinoscopy. Second, the dry standard and "Mirza" tele-lens retinoscopy were performed in 78 eyes from 39 children aged 7-12 years with good cooperation and next, the procedure was repeated using cyclopentolate drops and then the results of the two methods were compared, and at the end, the dry "Mirza" tele-lens retinoscopy was done in the 60 eyes of 31 uncooperative infants with a mean age of 21.85 ± 8.79 months for evaluating the feasibility of the "Mirza" tele-lens retinoscopy procedure. The intraclass correlation coefficient (ICC) and Bland-Altman plot for assessment of agreement between the findings of two retinoscopic methods in dry and cyclo conditions were used.

RESULTS

The comparison between the dry standard and "Mirza" tele-lens retinoscopic results with means of 1.39 ± 1.43 and1.36 ± 1.39, respectively were not statistically significant (p > 0.05). Besides, comparing the mean cycloplegic results of two methods (standard vs. "Mirza" tele-lens), the difference was not statistically significant (2.37 ± 1.44 vs. 2.41 ± 1.37) (p > 0.05). Moreover, Two-way repeated measures ANOVA revealed no significant retinoscopy method × use of drops interaction (P = 0.103) in comparing two methods of the standard and "Mirza" tele-lens retinoscopy. ICC results indicated high agreement between two methods in both dry (ICC = 0.993) and cyclo (ICC = 0.989) conditions.

CONCLUSIONS

The "Mirza" tele-lens retinoscopy method can be performed with satisfactory results in infants and children who do not cooperate for the standard procedure of measuring the refractive errors.

Performance of Plusoptix A09 Photo Screener in Refractive Error Screening in School Children Aged between 5 and 15 Years in the Southern Part of India

Purpose:

To evaluate the performance of Plusoptix A09 in detecting ametropia, warranted against frequently-used technique of retinoscopy in children attending school (5–15 years) and its probability as a screening tool.

Methods:

This study was the subset of a larger epidemiological study visual acuity refractive error squint conducted in schools to determine the prevalence of ocular morbidity among the 5–15 years' school children population. Every 7^th student in the class (each school had mean value of 100 students) was randomly selected for this study after ascertaining their eligibility as per the inclusion criteria. A cohort of a total of 150 children within the age group of 5–15 (mean, 10.21 ± 2.83) years were recruited from 11 schools of Udupi district. Students with best corrected visual acuity of 20/20, refractive error within ±5.00 diopter (D), without any eccentric fixation, and no history of ocular pathology or seizures were recruited. Refractive error was tested by Plusoptix photorefractor followed by non-cycloplegic and cycloplegic retinoscopic techniques. The examiners performing these tests were masked and unware of the findings. Bland Altman plotted the agreement between the techniques, followed by the receiver operating characteristic curve (ROC), and sensitivity of Plusoptix.

Results:

One-way analysis of variance calculated statistical differences among Plusoptix, objective retinoscopy, and cycloplegic retinoscopy for mean spherical value (1.12 ± 1.16 D, 0.65 ± 0.69 D, and 0.8 ± 0.82 D), cylindrical value (−0.83 D ± 1.27, −0.32 D ± 0.86, and −0.34 D ± −0.93), and spherical equivalent value (0.71 D ± 1.06, 0.45 D ± 0.7, and 0.61 D ± 0.81), with P = 0.0001, 0.0001, and 0.097, respectively. Bland Altman plots showed good agreement for spherical equivalent values of Plusoptix and objective retinoscopy. However, the area under the ROC curve (0.386) suggests that lower diagnostic ability of this device in this age group population in comparison to retinoscopy (0.575) with the sensitivity and specificity of Plusoptix was 69.2% and 84.8%.

Conclusions:

This study fails to report ideal sensitivity mandated for a screening tool, although good specificity and agreement are observed. Along with retinoscopy, this tool will be effective in screening a children's population aged between the age group of 5 and 15 years.

Comparison of open-field autorefraction, closed-field autorefraction, and retinoscopy for refractive measurements of children and adolescents in Taiwan

PURPOSE

To evaluate the accuracy and effectiveness of noncycloplegic and cycloplegic autorefraction using two types of autorefractors (ARs) compared with retinoscopy in children and adolescents.

METHODS

This cross-sectional study included 308 students (6-17 years old) from eastern Taiwan. Noncycloplegic and cycloplegic refractive measurements were obtained using open-field AR (Shin-Nippon NVision-K 5001), closed-field AR (Topcon KR-800), and cycloplegic retinoscopy. Three optical components emerged from the measurements: spherical equivalent (M) and two Jackson cross-cylinder values (J0 and J45). Agreement between both ARs and retinoscopy was evaluated using intraclass correlation coefficient. Measurement discrepancies from retinoscopy among different ARs and cycloplegic status were compared using repeated measures ANOVA and receiver operating characteristic curve analysis.

RESULTS

Compared with retinoscopy, measurements obtained before and after cycloplegia with both ARs showed excellent reliability for evaluating M and J0 and fair to good results for J45. More myopic results were obtained using KR-800 before cycloplegia; more hyperopic results were obtained using KR-800 and NVision-K 5001 after cycloplegia(all p < 0.05). J45 data obtained using NVision-K 5001 were closest to those obtained by retinoscopy; J0 data obtained using both ARs were comparable with retinoscopy after cycloplegia. NVision-K 5001 outperformed KR-800 in refractive measurements, particularly in hyperopia diagnosis among younger children.

CONCLUSIONS

Both autorefractors showed great agreement with retinoscopy. Results obtained using NVision-K 5001 without cycloplegia were most similar to those by retinoscopy, especially for oblique astigmatism and hyperopia detection in younger children. For large vision screening in elementary school, Shin-Nippon NVision-K 5001 might be a more suitable autorefractor.

Intraocular lens power calculation for the equine eye

Background

Phacoemulsification and intraocular lens (IOL) implantation during cataract surgery in horses occur with increasing frequency. To reduce the postoperative refractive error it is necessary to determine the proper IOL power. In the present study retinoscopy, keratometry and ultrasonographic biometry were performed on 98 healthy equine eyes from 49 horses. The refractive state, corneal curvature (keratometry) and the axial location of all optical interfaces (biometry) were measured. The influences of breed, height at the withers, gender and age on values obtained and the comparison between the left and right eye were evaluated statistically. Corresponding IOL power were calculated by use of Binkhorst and Retzlaff theoretical formulas.

Results

Mean ± SD refractive state of the horses was + 0.32 ± 0.66 D. Averaged corneal curvature for Haflinger, Friesian, Pony, Shetland pony and Warmblood were 21.30 ± 0.56 D, 20.02 ± 0.60 D, 22.61 ± 1.76 D, 23.77 ± 0.94 D and 20.76 ± 0.88 D, respectively. The estimated postoperative anterior chamber depth (C) was calculated by the formula C = anterior chamber depth (ACD)/0.73. This formula was determined by a different research group. C and axial length of the globe averaged for Haflinger 9.30 ± 0.54 mm and 39.43 ± 1.26 mm, for Friesian 10.12 ± 0.33 mm and 42.23 ± 1.00 mm, for Pony 8.68 ± 0.78 mm and 38.85 ± 3.13 mm, for Shetland pony 8.71 ± 0.81 mm and 37.21 ± 1.50 mm and for Warmblood 9.39 ± 0.51 mm and 40.65 ± 1.30 mm. IOL power was calculated with the Binkhorst and Retzlaff theoretical formulas. Calculated IOL power for the several breeds ranged from 18.03 D to 19.55 D. The mean value across all horses was 18.73 D determined with Binkhorst formula and 18.54 D determined with Retzlaff formula.

Conclusions

Mean result of this study is: an 18.5 D IOL seemed to be the most appropriate to achieve emmetropia after IOL implantation in horses. Cataract surgery without IOL implantation results in hyperopic and visual compromised horses. Retinoscopy, keratometry and ultrasonographic biometry should be performed on every affected horse and postoperative visual outcome should be determined.

Comparison of the refractive measurements with hand-held autorefractometer, table-mounted autorefractometer and cycloplegic retinoscopy in children

Purpose

To evaluate the performance of the hand-held and table-top autorefractokeratometer in measuring refractive errors by comparing them with cycloplegic retinoscopy.

Methods

Included in the study were 112 eyes of 112 pediatric patients whose mean age was 6.78 ± 2.61 years (range, 2 to 12 years). The refractive errors of all the eyes were measured with and without cycloplegia using a hand held autorefractokeratometer (Retinomax K-plus 3), table top autorefractokeratometer (Canon RK-F1) and performing cycloplegic retinoscopy. The spherical equivalent, cylindrical axis and keratometer values were statistically compared.

Results

The mean spherical equivalent obtained from the Retinomax K-plus 3 was significantly less hyperopic than that of Canon RK-F1 (p = 0.004) before cycloplegia. When the Bland Altman analysis was performed in comparisons of spherical equivalent values measured with the Retinomax K-plus 3, Canon RK-F1 and cycloplegic retinoscopy, it was seen that almost all of the differences between the measurements remained within the range of ±2 standard deviation. Good agreement was found between Retinomax K-plus 3 and Canon RK-F1 for the Jackson cross-cylinder values at axis 0° and 45°; keratometer values respectively.

Conclusions

The refractive error components were highly correlated between the two instruments and cycloplegic retinoscopy.

Can retinoscopy keep up in keratoconus diagnosis?

PURPOSE

To evaluate the diagnostic potential of retinoscopy in comparison with Amsler-grading, Pentacam and Ocular Response Analyzer (ORA) in classifying keratoconus stages.

METHODS

Clinical examination, retinoscopy, Pentacam and ORA were performed in 126 patients. Data of Amsler, retinoscopy, topographic keratoconus classification (TKC) of Pentacam and keratoconus match probability (KMP) of ORA were analyzed. Each of these four classification techniques quotes keratoconus into stage 0 (normal) to 4 (severe). Descriptive analysis and cross tables were used to compare the different devices.

RESULTS

For retinoscopy the distribution in the five keratoconus grades normal/suspect/mild/moderate/severe (in numbers) was 34/33/34/17/8. For Amsler it was 37/36/35/12/4, for TKC 38/17/34/31/4, for KMP 32/34/32/15/9. The cross tables show large classification differences of all devices. Overall, classification of retinoscopy and Amsler/TKC/KMP is congruent in 51.6%/36.3%/39.8% of the cases. Of all eyes, Amsler was congruent with TKC/KMP in 54.0%/48.4%, and TKC and KMP were congruent in 53.3%. In a binary decision (normal vs. any stage of mild/moderate/severe) matching between retinoscopy and Amsler/TKC/KMP was 98.6%/88.8%/82.4%. Sensitivity/specificity for retinoscopy and Amsler, TKC, KMP was 98.8%/94.0%, 84.4%/100% and 80.0%/79.1%.

CONCLUSIONS

The congruence of keratoconus classification was very poor of all the techniques tested in our study. This applies to objective measures such as TKC, KMP as well as clinical classification techniques such as Amsler and retinoscopy. Compared to TKC and KMP, retinoscopy underestimates keratoconus stages. In contrast, the performance of binary decisions (normal vs. keratoconus) shows a high sensitivity and specificity. Retinoscopy, however, showed a clear clinical use in confirming the diagnosis of keratoconus.