The Use of Infrared Auto Refractometer for Meibomian Gland Imaging

Introduction This study proposes the utility of an infrared auto refractometer for meibography and compares miebographs obtained by an auto refractometer to meibographs obtained by a designated meibography machine. Methods A prospective observational comparative study of meibographs of patients with clinical signs of meibomian gland dysfunction (MGD) using a designated meibography machine and an infrared auto refractometer. Five masked, experienced interpreters graded the images of the two machines. The Kappa test was used to calculate Intra-rater and inter-rater agreements between the meibography machine and automated refractor grading of meibomian gland dysfunction. Results High-quality photos of all 30 eyes delineating the meibomian glands (MG) were successfully obtained with both the meibography machine and the autorefractor. Both methods had a good intra-rater agreement (κ= 0.667 to 0.784, average 0.738). Poor to fair interrater agreement was noticed in the grading of autorefractor images (k= -0.030 to 0.343, average 0.092) and poor to moderate agreements between investigators for meibography machine images (K= -0.016 to 0.420, average 0.173). Conclusion A commercially available auto refractometer could capture high-quality non-contact IR digital meibographs.

A Comparison of Autorefraction and Subjective Refraction in an Academic Optometry Clinic

BACKGROUND

 Refractive error is the most common cause of decreased visual acuity. Refractive measurement in adults consists of cycloplegic (objective) and manifest (subjective) refraction. Although the effectiveness of autorefraction is a crucial factor, there needs to be more information on its accuracy and precision on each autorefractor compared with subjective measurement in Thai patients.

OBJECTIVE

 To compare the accuracy and precision of the two autorefractors' findings in Rajavithi Hospital, OptoChek Plus, and TOMEY Auto Refractometer RC-5000, with each other and with those of the subjective method.

MATERIALS & METHODS

 An observational study was conducted at the Ophthalmology clinic in Rajavithi Hospital from March 1, 2021, to March 31, 2022. All subjects were tested using the two autorefractors (OptoChek Plus and TOMEY Auto Refractometer RC-5000) and subjective refraction. One eye per subject was included in the study.

RESULTS

 Forty-eight patients (48 eyes) were enrolled in the study. The difference between spherical powers obtained by OptoChek and subjective refraction was not significantly different; however, there was a significant difference between those calculated by Tomey and the subjective method (p=0.77, p=0.04 respectively). The variations between cylindrical powers arrived at by the two autorefraction techniques and those calculated by the subjective method were significantly different (OptoChek and Tomey p-=0.01, p-value<0.001, respectively). In addition, 95% of the limit of agreement (95% of LOA) was low in the cylindrical measurement of each autorefractor compared with subjective refraction. (84.61%, 86.36%, respectively). No statistically significant difference between the spherical equivalent calculated by the two autorefractors and that of subjective refraction was observed in the present study (OptoChek: p-value=0.26 and Tomey: p-value=0.77).

CONCLUSIONS

 There was a clinically significant difference between the cylindrical power calculated by the two autorefractors and those obtained from subjective refraction. Patients with high astigmatism should be monitored closely when measured by autorefractors, as there can be a slightly lower agreement between objective and subjective refraction.

Effect of multifocal spectacle lenses on accommodative errors over time: Possible implications for myopia control

The study purpose was to improve understanding of how multifocal spectacle lenses affect accommodative errors and whether this changes over time. Fifty-two myopes aged 18 to 27 years were allocated randomly to one of two progressive addition lens (PAL) types with 1.50 D additions and different horizontal power gradients across the near-periphery boundary. Lags of accommodation were determined with a Grand Seiko WAM-5500 autorefractor and a COAS-HD aberrometer for several near distances with the distance correction and the near PAL correction. For the COAS-HD the neural sharpness (NS) metric was used. Measures were repeated at three-month intervals over 12 months. At the final visit, lags to booster addition powers of 0.25, 0.50, and 0.75 D were measured. Except at baseline, both PALs' data were combined for analysis. For the Grand Seiko autorefractor, both PALs reduced accommodative lag at baseline compared with SVLs (p < 0.05 and p < 0.01 at all distances for PAL 1 and PAL 2, respectively). For the COAS-HD, at baseline PAL 1 reduced accommodative lag at all near distances (p < 0.02), but PAL 2 only at 40 cm (p < 0.02). Lags measured with COAS-HD were greater for shorter target distances with PALs. After 12 months' wear, the PALs no longer reduced accommodative lags significantly, except at 40 cm distance, but 0.50 D and 0.75 D booster adds decreased the lags to those measured at baseline or less. In conclusion, for PALs to reduce accommodative lag effectively, addition power should be tailored to typical working distances and after the first year of wear should be boosted by at least 0.50 D to maintain efficacy.

Refractive errors in mixed breed dogs of different ages

The purpose of the study was to evaluate the occurrence and range of refractive errors in dogs of different ages. A total of 99 clinically healthy, mixed-breed mesocephalic dogs were included in the study and divided into three different age groups according to the current human/pet analogy chart: 40 adults (23 males, 17 females, 1-8 years old, 3-70 kg), 21 seniors (14 males, 7 females, 6-11 years old, 7-42 kg), and 38 geriatrics (22 males, 16 females, 8-13 years old, 5-45 kg). All the dogs underwent an ophthalmic examination, including Schirmer tear test, tonometry, biomicroscopy, and ophthalmoscopy. Neither eye drops nor pharmacological sedatives were administered before the autorefractometry. The refractive states were assessed bilaterally using a hand-held Retinomax 3 (Righton) autorefractor. The results underwent statistical analysis using Statistica v12 software (ANOVA and t-test). A P-value < 0.05 was considered as significant. Emmetropia, defined as a refractive state > -0.5 D and < +0.5 D, was found in 36% of the adult, 43% of the senior, and 38% of the geriatric patients. Anisometropia was found in 1% of the adult, 9.5% of the senior and 5.5% of the geriatric dogs when the refractive power of the two eyes differed ≥ 1.0 myopia ≤ -0.5 D and hyperopia ≥ +0.5 D were found in 23% and 41% of the adult eye globes as well as 24% and 33% in the senior dogs and 15% and 47% in the geriatric dogs, respectively. The maximal values of the myopia in the adult and geriatric dogs were -2.5 D and -2.75 D, respectively. The maximal values of the hyperopia in the adult and geriatric dogs were 1.75 D and 2.5 D, respectively. No statistically significant correlation was found between the groups. Ametropia is a common refractive state for dogs of different ages. The most frequent refractive state in ametropic mixed-bed dogs in all age groups is hyperopia.

Validation of the PowerRef 3 for Measuring Accommodation: Comparison With the Grand Seiko WAM-5500A Autorefractor

Purpose

This validation study examines the PowerRef 3 as a method for measuring accommodation objectively. We assess agreement with refractive measurements obtained simultaneously by the Grand Seiko WAM-5500A autorefractor.

Methods

Refractive measurements were recorded simultaneously using the PowerRef 3 and WAM-5500A in 32 noncyclopleged participants aged 15 to 46 years. Accommodative states were recorded for 10 seconds at six accommodative demands (5 diopters [D], 4 D, 3 D, 2.5 D, 2 D, and 0 D) while participants fixated a high-contrast Maltese cross. WAM-5500A measurements were converted to power in the vertical meridian for comparison with PowerRef 3 data. Dioptric difference values were computed, and agreement was assessed using Bland-Altman plots with 95% limits of agreement (LOA) and intraclass correlation coefficient analyses.

Results

The mean absolute dioptric differences measured 0.14 D or less across accommodative demands. Analyses showed an excellent intraclass correlation coefficient across the tested demands (0.93). Bland-Altman plots indicated a bias of -0.02 D with 95% LOA of -1.03 D to 0.99 D. The 95% LOA was smallest for the 3 D demand (-0.71 D to 0.64 D), and largest at 5 D demand (-1.51 D to 1.30 D).

Conclusions

The mean dioptric differences between the PowerRef 3 and WAM-5500A autorefractor were small and not clinically significant. While some variability in agreement was observed depending on the tested demand, the PowerRef 3 demonstrated good agreement with the WAM-5500A.

Translational Relevance

The PowerRef 3 may be used to obtain objective measures of accommodation both monocularly and binocularly and provides a more flexible method, especially in pediatric populations.

Accommodation lags are higher in myopia than in emmetropia: Measurement methods and metrics matter

Purpose

To determine whether accommodative errors in emmetropes and myopes are systematically different, and the effect of using different instruments and metrics.

Methods

Seventy‐six adults aged 18–27 years comprising 24 emmetropes (spherical equivalent refraction of the dominant eye +0.04 ± 0.03 D) and 52 myopes (−2.73 ± 0.22 D) were included. Accommodation responses were measured with a Grand Seiko WAM‐5500 and a Hartmann–Shack Complete Ophthalmic Analysis System aberrometer, using pupil plane (Zernike and Seidel refraction) and retinal image plane (neural sharpness—NS; and visual Strehl ratio for modulation transfer function—VSMTF) metrics at 40, 33 and 25 cm. Accommodation stimuli were presented to the corrected dominant eye, and responses, referenced to the corneal plane, were determined in the fellow eye. Linear mixed‐effects models were used to determine influence of the refractive group, the measurement method, accommodation stimulus, age, race, parental myopia, gender and binocular measures of heterophoria, accommodative convergence/accommodation and convergence accommodation/convergence ratios.

Results

Lags of accommodation were affected significantly by the measurement method (p < 0.001), the refractive group (p = 0.003), near heterophoria (p = 0.002) and accommodative stimulus (p < 0.05), with significant interactions between some of these variables. Overall, emmetropes had smaller lags of accommodation than myopes with respective means ± standard errors of 0.31 ± 0.08 D and 0.61 ± 0.06 D (p = 0.003). Lags were largest for the Grand Seiko and Zernike defocus, intermediate for NS and VSMTF, and least for Seidel defocus.

Conclusions

The mean lag of accommodation in emmetropes is approximately equal to the previously reported depth of focus. Myopes had larger (double) lags than emmetropes. Differences between methods and instruments could be as great as 0.50 D, and this must be considered when comparing studies and outcomes. Accommodative lag increased with the accommodation stimulus, but only for methods using a fixed small pupil diameter.

Clinical evaluation of autorefraction and subjective refraction with and without cycloplegia in Chinese school-aged children: a cross-sectional study

BACKGROUND

The accuracy of open-field autorefractors is important for vision screening, clinical care, and vision research, especially in patients with childhood myopia. TOPCON KR3000 autorefractor was conventional autorefractor and subjective refraction after cycloplegia was gold criteria for assessing the refraction. Results of refractive error in Chinese school-aged children obtained by three methods were evaluated and compared.

METHODS

A cross-sectional study was conducted. A total of 89 patients (with a total of 177 eyes) diagnosed as refractive error in the Affiliated Hospital of Nanjing University of Chinese Medicine from July 2020 to September 2020 were sequentially enrolled in this study. All subjects underwent routine ophthalmic examination to exclude other ocular diseases and had a best corrected visual acuity no less than 0.1 The spherical diopter (SD), spherical equivalence (SE), and astigmatism (J0 and J45) were determined in patients before cycloplegia using two autorefractors, and again after cycloplegia. Subjective refraction results were obtained simultaneously after cycloplegia as gold criteria for comparison. A comparison of data between three methods was performed using paired t-tests and presented graphically using Bland-Altman plots.

RESULTS

Before cycloplegia, the SD and SE results from WAM were 0.14 D and 0.12 D more positive than the reading from TOPCON (P=0.011 and P=0.021, respectively). The SD measured by WAM and TOPCON was 0.31 D and 0.45 D more negative than the values obtained by subjective refraction after cycloplegia, respectively (P<0.001 and P<0.001, respectively). The SE readings also showed a similar trend (P<0.001, P<0.001). After cycloplegia, the SD and SE measurement obtained with WAM were 0.13 D and 0.12 D more positive than those measured by TOPCON (P<0.001 and P<0.001, respectively), and this was not significantly different to the results obtained using subjective refraction. However, the results of SD, SE, and J0 measured by the TOPCON were significantly different from the results obtained using subjective refraction (P<0.001, P<0.001, and P=0.002, respectively).

CONCLUSIONS

In clinical application, the measurements obtained with the WAM-5500 autorefractor were more reliable than those of the TOPCON KR3000 autorefractor in patients with or without cycloplegia. The WAM-5500 Autorefractor represents a reliable and valid objective refraction tool for optometric practice.

Does the Accuracy and Repeatability of Refractive Error Estimates Depend on the Measurement Principle of Autorefractors?

Purpose

The purpose of this study was to determine the accuracy and repeatability of refractive errors obtained using three autorefractors based on different measurement principles, vis-à-vis, gold-standard retinoscopy.

Methodology

Accuracy of noncycloplegic, sphero-cylindrical refractive error of 234 eyes was obtained using the rotary prism-based RM-8900 closed-field autorefractor, photorefraction based Spot vision screener, wavefront aberrometry based E-see, and streak retinoscopy by four different examiners, masked to the results of each other. Intersession repeatability of autorefractors was determined by repeat measurements in a subset of 40 subjects.

Results

Retinoscopy values of M, J₀, and J₄₅ power vectors for the cohort ranged from -10.2 to 8 D, -1.4 to 1.8 D, and -0.9 to 1.2 D, respectively. Across autorefractors, the interequipment bias of M and J₀ power vectors were statistically insignificant (< ±0.5 D; P > 0.05) but the corresponding limits of agreement were ±2.5 and ±1 D, respectively, without any trend across instruments or the patient's age (P > 0.5). Repeatability of M and J₀ power vectors were ±0.75 D and ±0.40 D, respectively, across autorefractors. The range of J₄₅ power vector was too narrow for any meaningful analysis.

Conclusions

Refractive errors measured using autorefractors operating on different principles show minimal bias and good short-term repeatability but relatively large agreement limits, vis-à-vis, retinoscopy. Among them, the wavefront aberrometry based E-see autorefractor performs relatively better in all measurement parameters evaluated here.

Translational Relevance

Although autorefractor estimates of noncycloplegic refractive error appears independent of their measurement principle, their relatively poor agreement with gold-standard retinoscopy warrants caution while used for screening and quantification of refractive errors.

Accuracy, speed and repeatability of the voice assisted subjective refractor (VASR)

PURPOSE

To compare the accuracy, speed and repeatability of the voice assisted subjective refractor (VASR) to traditional refractive methods.

METHODS

Fifty healthy adult subjects were examined by autorefractor, followed by subjective phoropter refinement. Subjects were then evaluated using the VASR (Vmax Vision) to obtain an objective and subjective result. Three total assessments were performed for each subject using each of the methods described. Corrected visual acuity was recorded for each eye after each procedure. The total time was measured for both the traditional and VASR refraction.

RESULTS

A comparison of the results obtained by traditional refraction and VASR revealed no statistically significant difference from the mean in equivalent sphere measurements (P=0.1383), and the datasets were highly correlated (r=0.993). The data comparisons for cylinder power and axis were similar (cylinder: P=0.6377, r=0.864) (axis: P=0.6991, r=0.738). VASR, on average, required 71 additional seconds to complete when compared to traditional phoropter refraction. In terms of repeatability, the average difference noted upon repeat of equivalent sphere power was 0.01 D for the phoropter (P=0.98) and 0.10 D for the VASR (P=0.23). For sphere power, the average difference was 0.02 D for the phoropter (P=0.55) and 0.07 D for the VASR (P=0.58). For cylinder power, the average difference was 0.02 D for the phoropter (P=0.11) and 0.03 D for the VASR (P=0.39). For all refractive methods, the differences between measurements amounted to ≤0.10 diopters, which is neither clinically nor statistically significant.

CONCLUSION

Refractive error results obtained with the VASR were not statistically different from those achieved using traditional phoropter methods. Time elapsed for the VASR was slightly longer than a more traditional refractive sequence. The VASR demonstrated clinically and statistically significant repeatability of measurement, consistent with traditional refraction.

Validity of autorefractor based screening method for irregular astigmatism compared to the corneal topography- a cross sectional study

AIM

To present a method of screening for irregular astigmatism with an autorefractor and its determinants compared to corneal topography.

METHODS

This cross-sectional validity study was conducted in 2013 at an eye hospital in Spain. A tabletop autorefractor (test 1) was used to measure the refractive status of the anterior surface of the cornea at two corneal meridians of each eye. Then corneal topography (test 2) and Bogan's classification was used to group eyes into those with regular or no astigmatism (GRI) and irregular astigmatism (GRII). Test 1 provided a single absolute value for the greatest cylinder difference (Vr). The receiver operating characteristic (ROC) were plotted for the Vr values measured by test 1 for GRI and GRII eyes. On the basis a Vr value of 1.25 D as cut off, sensitivity, specificity were also calculated.

RESULTS

The study sample was comprised of 260 eyes (135 patients). The prevalence of irregular astigmatism was 42% [95% confidence interval (CI): 36, 48]. Based on test 2, there were 151 eyes in GRI and 109 eyes in GRII. The median Vr was 0.75 D (25% quartile, 0.5 D) for GRI and 1.75 D (25% quartile, 1.25 D) for GRII. The area under curve was 0.171 for GRI and 0.83 for GRII. The sensitivity of test I was 78.1% and the specificity was 76.1%.

CONCLUSION

A conventional autorefractor can be effective as a first level screening method to detect irregular corneal astigmatism in places where corneal topography facilities are not available.

Accommodation stimulus and response determinations with autorefractors

PURPOSE

To develop equations for accommodation stimulus and accommodation response with autorefractors when the accommodation stimulus is produced by combinations of object distances and lenses placed in front of eyes, and to give worked examples using these equations.

METHODS

Simple ray tracing was used to determine stimulus and response equations, taking into account the reference positions for targets, for refraction, and for autorefractor readings.

RESULTS

Several examples applying equations are provided. Features of these examples include evaluating approximate calculations that have been used previously, demonstrating which equations should be used in different circumstances, how to substitute numbers into equations, how to deal with discrepancies between subjective and objective refraction, and how to deal with astigmatism. Problems associated with measuring accommodation response by placing lenses in front of the eye are discussed.

CONCLUSIONS

Accurate equations for accommodation stimulus and accommodation response for a range of accommodation stimuli in different setups have been developed.

Vision screening for children 36 to <72 months: recommended practices

PURPOSE

This article provides recommendations for screening children aged 36 to younger than 72 months for eye and visual system disorders. The recommendations were developed by the National Expert Panel to the National Center for Children's Vision and Eye Health, sponsored by Prevent Blindness, and funded by the Maternal and Child Health Bureau of the Health Resources and Services Administration, United States Department of Health and Human Services. The recommendations describe both best and acceptable practice standards. Targeted vision disorders for screening are primarily amblyopia, strabismus, significant refractive error, and associated risk factors. The recommended screening tests are intended for use by lay screeners, nurses, and other personnel who screen children in educational, community, public health, or primary health care settings. Characteristics of children who should be examined by an optometrist or ophthalmologist rather than undergo vision screening are also described.

RESULTS

There are two current best practice vision screening methods for children aged 36 to younger than 72 months: (1) monocular visual acuity testing using single HOTV letters or LEA Symbols surrounded by crowding bars at a 5-ft (1.5 m) test distance, with the child responding by either matching or naming, or (2) instrument-based testing using the Retinomax autorefractor or the SureSight Vision Screener with the Vision in Preschoolers Study data software installed (version 2.24 or 2.25 set to minus cylinder form). Using the Plusoptix Photoscreener is acceptable practice, as is adding stereoacuity testing using the PASS (Preschool Assessment of Stereopsis with a Smile) stereotest as a supplemental procedure to visual acuity testing or autorefraction.

CONCLUSIONS

The National Expert Panel recommends that children aged 36 to younger than 72 months be screened annually (best practice) or at least once (accepted minimum standard) using one of the best practice approaches. Technological updates will be maintained at http://nationalcenter.preventblindness.org.

Comparison of the Retinomax hand-held autorefractor versus table-top autorefractor and retinoscopy

AIM

To compare noncycloplegic and cycloplegic results of Retinomax measurements with findings achieved after cycloplegia using table-top autorefractor and retinoscopy.

METHODS

The study included 127 patients (mean age 96.7mo, range 21 to 221). Retinomax (Rmax) (Nikon Inc., Japan) was used to obtain noncycloplegic refraction. Under cycloplegia, refraction was measured with Rmax, table-top autorefractor (TTR) (Nikon NRK 8000, Inc., Japan) and retinoscopy. The values of sphere, spherical equivalent, cylinder and axis of cylinder were recorded for Rmax, TTR and retinoscopy in each eye. All results were analyzed statistically.

RESULTS

THE MEAN SPHERIC VALUES (SV), SPHERICAL EQUIVALENT VALUES (SEV) AND CYLINDRICAL VALUES (CV) OF THE NONCYCLOPLEGIC RMAX (SV: 0.64 D, SEV: 0.65 D and CV: 0.03 D, respectively) were found to be significantly lower than cycloplegic TTR (1.43 D, 1.38 D and 0.3 D; P=0.012, P=0.011 and P=0.04, respectively) and retinoscopy (1.34 D, 1.45 D and 0.23 D; P=0.04, P=0.002 and P=0.045, respectively). Mean cycloplegic SV, SEV, CV were not significantly different between Rmax and TTR, Rmax and retinoscopy, TTR and retinoscopy. Cycloplegic or noncycloplegic axis values were not different between any method.

CONCLUSION

Rmax may be used successfully as a screening tool but may not be accurate enough for actual spectacle prescription. Cycloplegic Rmax measurements may be able to identify refractive error in children because of approximate results to retinoscopy.

How representative is the 'Representative Value' of refraction provided by the Shin-Nippon NVision-K 5001 autorefractor?

PURPOSE

The aim of the study was to evaluate the level of agreement between the 'Representative Value' (RV) of refraction obtained from the Shin-Nippon NVision-K 5001 instrument with values calculated from individual measurement readings using standard algebraic methods.

METHODS

Cycloplegic autorefraction readings for 101 myopic children aged 8-13 years (10.9 ± 1.42 years) were obtained using the Shin-Nippon NVision-K 5001. Ten autorefractor measurements were taken for each eye. The spherical equivalent (SE), sphere (Sph) and cylindrical component (Cyl) power of each eye were calculated, firstly, by averaging the 10 repeated measurements (Mean SE, Mean Sph and Mean Cyl), and secondly, by the vector representation method (Vector SE, Vector Sph and Vector Cyl). These calculated values were then compared with those of RV (RV SE, RV Sph and RV Cyl) provided by the proprietary software of the NVision-K 5001 using one-way analysis of variance (anova). The agreement between the methods was also assessed.

RESULTS

The SE of the subjects ranged from -5.37 to -0.62 D (mean ± SD, = -2.89 ± 1.01 D). The Mean SE was in exact agreement with the Vector SE. There were no significant differences between the RV readings and those calculated using non-vectorial or vectorial methods for any of the refractive powers (SE, p = 0.99; Sph, p = 0.93; Cyl, p = 0.24). The (mean ± SD) differences were: RV SE vs Mean SE (and also RV SE vs Vector SE) -0.01 ± 0.06 D; RV Sph vs Mean Sph, -0.01 ± 0.05 D; RV Sph vs Vector Sph, -0.04 ± 0.06 D; RV Cyl vs Mean Cyl, 0.01 ± 0.07 D; RV Cyl vs Vector Cyl, 0.06 ± 0.09 D. Ninety-eight percent of RV reading differed from their non-vectorial or vectorial counterparts by less than 0.25 D.

CONCLUSION

The RV values showed good agreement to the results calculated using conventional methods. Although the formula used to calculate RV by the NVision-K 5001 autorefractor is proprietary, our results provide validation for the use of RV measurements in clinical practice and vision science research.

Clinical comparison of the Welch Allyn SureSight™ handheld autorefractor vs. streak retinoscopy in dogs

OBJECTIVE

To compare the Welch Allyn SureSight™ wavefront autorefractor with retinoscopy in normal dogs.

ANIMALS STUDIED

Fifty privately owned dogs (100 eyes) of 20 breeds, free of ocular disease. Mean ± SD age: 5.7 ± 3.25 years (range: 6 months-13 years).

PROCEDURES

The refractive error was determined in each eye by two experienced retinoscopists using streak retinoscopy as well as by an autorefractor operated by two different examiners. Measurements were performed before and approximately 30-45 min after cycloplegia was induced by cyclopentolate 0.5% and tropicamide 0.5% ophthalmic solutions.

RESULTS

Mean ± SD noncyclopleged retinoscopy net sphere was -0.55 ± 1.14 (range: -3.75 to 3.5) diopters (D). Mean cyclopleged retinoscopy net sphere was -0.52 ± 1.18 (range: -4.25 to 2) D. Mean ± SD noncyclopleged autorefractor spherical equivalent (SE) was -0.42 ± 1.13 D (range: -3.36 to 2.73) D. Mean cyclopleged autorefractor SE was 0.10 ± 1.47 (range: -5.62 to 3.19) D. Noncyclopleged autorefraction results were not significantly different from streak retinoscopy (whether noncyclopleged or cyclopleged, P = 0.80 and P = 0.26, respectively). Cyclopleged autorefraction results were significantly different from noncyclopleged or cyclopleged streak retinoscopy (P < 0.0001 in both states). There was no significant difference between noncyclopleged and cyclopleged streak retinoscopy (P = 0.97).

CONCLUSIONS

Noncyclopleged autorefraction shows good agreement with streak retinoscopy in dogs and may be a useful clinical technique. Cycloplegia does not significantly affect streak retinoscopy results in dogs.

Comparison of the Retinomax and Palm-AR Auto-Refractors: a pilot study

PURPOSE

To compare the performance of two handheld auto-refractors, the Retinomax and the Palm-Automatic Refractometer (Palm-AR), for detecting significant vision disorders in pre-school children.

METHODS

Children attending Philadelphia PreKindergarten Head Start were screened with the Retinomax and Palm-AR and underwent a gold standard eye examination. The results of cycloplegic retinoscopy, cover testing, and visual acuity were used to classify children as having normal vision or one of four conditions: amblyopia, strabismus, significant refractive error, and reduced visual acuity. Pass/fail criteria for each instrument were selected to maximize overall sensitivity (with specificity set at 90% and at 94%) for detecting targeted disorders. Comparisons of sensitivities between the auto-refractors were performed using the exact McNemar test.

RESULTS

Testability was >99% for both instruments. Test time was similar for the two instruments (median 2 min; p=0.10). At 90% specificity, the sensitivity for detection of one or more targeted conditions was 74% for the Palm-AR and 78% for the Retinomax. At 94% specificity, the sensitivity for detection of one or more targeted conditions was 66% for both the Palm-AR and the Retinomax. At 90% specificity, the sensitivity for detecting significant refractive error was 84% for both auto-refractors, and at 94% specificity, the sensitivity was 76% for the Palm AR and 75% for the Retinomax. There were high correlations between the instruments for sphere (r=0.85) and cylinder (r=0.88) power. The mean difference between instruments was -0.13 diopters (D) (95% limit of agreement: -2.28 to 2.02) for sphere, and -0.15 D (95% limit of agreement: -0.89 to 0.59) for cylinder.

CONCLUSIONS

In this pilot study, the Retinomax and Palm-AR appear comparable with respect to testability, sensitivity, and specificity. There was strong agreement in readings of sphere and cylinder indicating that they may perform similarly in a screening setting.

Effects of age on dynamic accommodation

Visual accommodation plays a critical role in one's visual perception and activities of daily living. Age-related accommodation loss poses an increased risk to older adults' safety and independence. Although extensive effort has been made towards understanding the effect of age on steady-state accommodation, dynamic aspects of accommodation is still unknown. A study was therefore conducted to investigate age-related dynamic accommodative characteristics utilising a modified autorefractor. Ten individuals from each of three age groups (i.e. younger group: 20 to 29 years old; middle-aged group: 40 to 49 years old; older group: 60 to 69 years old) were recruited and their dynamic accommodation responses were examined. The laboratory experiment was designed to assess dynamic accommodation associated with an abrupt change from a constant far target (400 cm, 50 cd/m(2)) to a near target (70 cm, 100 cd/m(2) or 20 cd/m(2)), which aimed to simulate car dashboard reading behaviour while driving. The results of the study indicated that age and target intensity both had a significant impact on dynamic accommodation. These effects were attributed to both the age-related physiological limitation of the eye as well as to central neural processing delay. A method of measuring dynamic accommodation and the implications of the study are discussed. STATEMENT OF RELEVANCE: The results of the study indicate that age and target intensity both have a significant impact on dynamic accommodation. These effects are attributed to age-related physiological limitation of the eye as well as central neural processing delay and to decreased sensitivity of the cone photoreceptors. To enhance the visual performance of the ageing population involving dynamic accommodation, target distance and target light intensity should be carefully evaluated to facilitate effective viewing.