Evaluation of Aniseikonia in Patients with Successfully Treated Anisometropic Amblyopia Using Spatial Aniseikonia Test.

Anisometropic amblyopia is decreased visual acuity in one eye, and treatment consists of wearing complete corrective spectacles. Aniseikonia occurs with complete correction of anisometropia using spectacles. Aniseikonia has been ignored when treating pediatric anisometropic amblyopia because of the prevailing belief that anisometropic symptoms are suppressed by adaptation. However, the conventional direct comparison method for evaluating aniseikonia significantly underestimates the degree of aniseikonia. This study investigated whether the adaptation occurs due to long-term anisometropic amblyopia treatment in patients who have had successful amblyopia treatment using a spatial aniseikonia test with high accuracy and repeatability compared with the conventional direct comparison method. The amount of aniseikonia was not significantly different between the patients with successful amblyopia treatment and individuals with anisometropia without a history of amblyopia. In both groups, the aniseikonia per 1.00 D of anisometropia and the aniseikonia per 1.00 mm of aniso-axial length were comparable. The repeatability of the amount of aniseikonia using the spatial aniseikonia test did not differ significantly between the two groups, indicating a high degree of agreement. These findings suggest that aniseikonia is not adapted to amblyopia treatment and that aniseikonia increases as the difference between spherical equivalent and axial length increases.

Comparisons of size of foveal avascular zone area among children with posterior microphthalmos, high hyperopia, and normal eyes.

PURPOSE: To determine the area of the surface foveal avascular zone (FAZ) in children with posterior microphthalmos (PM), high hyperopia, and normal eyes using optical coherence tomography (OCT) and OCT angiography (OCTA). METHODS: Thirty-six children were studied including 6 cases 12 eyes of PM (mean age 9.5 ± 5.2 years), 15 cases 30 eyes of high hyperopia (6.9 ± 1.5 years), and 15 cases 30 eyes of healthy individuals (8.7 ± 1.7 years). The B- and C-scan images in all children were recorded by OCT and OCTA with a scanning area of 3.0 × 3.0 mm centered on the fovea. All images were corrected for axial length differences, and the area of the FAZ surface and central macular thickness (CMT) was measured manually and compared. RESULTS: The area of FAZ in the PM group was 0.007 ± 0.003 mm2, which was significantly smaller than that in the high hyperopia eyes at 0.286 ± 0.108 mm2 and healthy eyes at 0.318 ± 0.129 mm2 (both P < 0.001). The CMT in the PM group was 401.58 ± 33.60 mm, which was significantly thicker than in the high hyperopia eyes at 202.93 ± 12.28 mm and the normal eyes at 204.43 ± 18.76 mm. The area of the FAZ and CMT in the hyperopia group did not differ significantly from that of the normal healthy eyes. CONCLUSION: These findings indicate that patients with PM have a hypoplastic macular region, which must be considered in any treatment of these eyes.

Refractive changes with post-rotatory nystagmus in healthy individuals.

PURPOSE: Post-rotatory nystagmus has been used to detect autism spectrum disorders in clinical settings. Although previous studies have focused on eye movements, they did not evaluate the change in ocular refraction during post-rotatory nystagmus. This study aimed to evaluate the changes in ocular refraction during post-rotatory nystagmus in healthy individuals. METHODS: A total of 34 healthy volunteers (mean age ± standard deviation, 20.9 ± 0.6 years) participated in this study. The ocular refraction during post-rotatory nystagmus was measured using MR-6000 (Tomey Inc.) on quick mode with a sampling rate of 30 Hz under noncycloplegic and cycloplegic conditions. The amplitude of post-rotatory nystagmus was calculated on the basis of the anterior eye images, while the ocular refraction measurements were simultaneously recorded. The accommodative convergence per accommodation ratio was calculated using the heterophoria method. Video oculography was performed to measure the angle of convergence during post-rotatory nystagmus. RESULTS: The changes in ocular refraction during post-rotatory nystagmus were significantly greater under the noncycloplegic condition than under the cycloplegic condition. The changes in ocular refraction during the post-rotatory nystagmus were significantly and positively correlated with the amplitude of post-rotatory nystagmus under the noncycloplegic condition. The angle of convergence during post-rotatory nystagmus was significantly higher under the noncycloplegic condition than under the cycloplegic condition. The changes in the angle of convergence were significantly and positively correlated with the predicted accommodative convergence. CONCLUSIONS: These findings suggest that the accommodation was functional during the post-rotatory nystagmus to compensate for the retinal image slip, and the accommodative convergence can help weaken the nystagmus.

Evaluation of newly-developed aniseikonia testing method based on space eikonometry.

BACKGROUND: We have developed a new aniseikonia testing method based on the space eikonometry (ATSE) principle. The purpose of this study was to compare aniseikonia obtained by the ATSE to that of the conventional new aniseikonia tests (NAT), which is commonly used in Japan. METHODS: Thirty normal subjects (mean age: 22.8 years) without ocular disease except for refractive errors were studied. All of the subjects had normal binocular single vision with stereopsis. We excluded subjects with refractive errors greater than 1.00 D cylinder or anisometropia (spherical equivalent) greater than 1.00 D. We simulated overall aniseikonia of five and 10 per cent with afocal size lenses (HOYA, Tokyo, Japan) placed in the optical path of the fully corrected right eye. We measured aniseikonia three times with either the ATSE or NAT and the averages were used for the statistical analyses. RESULTS: The mean and standard deviation (SD) of aniseikonia determined by the ATSE was 5.1 ± 0.8 per cent with the five per cent afocal lens and 10.1 ± 0.8 per cent with the 10 per cent afocal lens. Aniseikonia was 2.8 ± 1.3 per cent with the five per cent afocal lens and 6.0 ± 2.5 per cent with the 10 per cent afocal lens by the NAT. The mean error was + two per cent of the theoretical value by the ATSE and -42 per cent by the NAT for both afocal lenses. CONCLUSION: We recommend the use of the new ATSE for quantitative determination of aniseikonia, as it is more accurate than the NAT.

Pattern visual evoked potentials elicited by organic electroluminescence screen.

PURPOSE: To determine whether organic electroluminescence (OLED) screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs). METHOD: Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA) screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan) screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years). RESULTS: The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT) screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. CONCLUSION: The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account.

Comparisons of pattern visually evoked potentials elicited by different response time liquid crystal display screens.

PURPOSE: To evaluate the usefulness of a liquid crystal display (LCD) with higher driving frequency and shorter response time (2 ms) as a visual stimulator to elicit pattern reversal visually evoked potentials (p-VEPs). METHOD: p-VEPs were recorded from 12 eyes of 12 healthy volunteers (28.3 ± 9 years). The p-VEPs elicited by a conventional cathode ray tube (CRT) screen were compared to those elicited by a high-speed LCD screen (2-ms LCD, GD245HQbid, Acer, Taipei, Taiwan). The luminance changes of each monitor were measured with a photodiode. RESULTS: During the reversal phase the luminance of the 2-ms LCD screen with 97% contrast was transiently reduced, which can elicit an electroretinogram (ERG) and therefore a flash VEP. The 2-ms LCD with 81% contrast checkerboard had a minimal luminance reduction during the reversal phase, and therefore no ERGs were elicited. No significant differences in the amplitude of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by a CRT or the 2-ms LCD screens as stimulators. CONCLUSION: The luminance change can elicit flash VEPs, and this artifact can be minimized by using a 2-ms LCD screen with reduced contrast of the checkerboard stimulus.