Chinese Journal of Optometry Ophthalmology and Visual science

Amblyopia is an ophthalmic diseases, usually derives from functional imbalance between two eyes during early development. Its treatment depends on the plasticity of the visual system. Once beyond the critical period, like older children with amblyopia and adult amblyopia, the treatment effect of traditional methods is powerless. Perceptual learning refers to a selectively improved performance of perceptual tasks after perceptual training, which physiological mechanism is the plasticity of the neural system. Recently, visual perceptual learning has been shown to significantly improve visual functions of human and animals. Additionally, perceptual learning could also improve impaired visual functions of amblyopia and other patients with visual dysfunction. Animal electrophysiological studies showed that perceptual learning resulted in an improvement of neuronal tuning properties. All these findings suggested that neural plasticity maintained in some degree even beyond the critical period of visual development.

Objective To evaluate the application of the binocular phase combination paradigm in quantifying interocular suppression in amblyopia, and to further assess the correlation between interocular suppression and visual deficits in amblyopia. Methods This was a cross-sectional study. Twenty-five normal controls and 51 patients with monocular amblyopia who had no prior treatment were included in this study. A binocular phase combination paradigm was used to examine an individual′s balance point when the two eyes were equally effective. The correlation between balance points and visual deficits, including the visual acuity of the amblyopic eye, stereoacuity and the degree of anisometropia were studied. Results The average balance point of the amblyopic group was 0.227±0.016, far lower than that in normal subjects (0.984±0.020), and the difference was statistically significant (t=27.316, P<0.01). There was a significant correlation between the balance point and the visual acuity of the amblyopic eye (r=-0.339, P<0.05), and between the balance point and stereoacuity (Titmus: r=-0.421, P<0.01; RDS: r=-0.548, P<0.01; Fishy: r=-0.553, P<0.01). However, no significant correlation was found between the balance point and the degree of anisometropia (r=-0.086, P>0.05). Conclusion A binocular phase combination paradigm can provide a quantitative measure of the binocular status of amblyopia, which is useful in clinical binocular examinations.

Objective To study the effect of levodopa (L-dopa) on monocular amblyopic children using chromatic pattern visual evoked potentials and FM 100-hue tests; to assess the role of levadopa on possible color vision recovery. Methods This was a prospective randomized controlled study. Fifty-five research candidates (110 eyes), ranging in age from 5 to 12 years, who were diagnosed with monocular amblyopia were randomly selected for the project from January 2014 to February 2015 at the Zhongshan Ophthalmic Center. The children were randomly divided into a control group of 27 cases (54 eyes) and a treatment group of 28 cases (56 eyes). The healthy eye of both groups was covered. The control group was treated with spectacles and the treatment group was treated with levodopa. Binocular visual acuity, refractive state, FM 100-hue color sorting and chromatic pattern visual evoked potentials (CP-VEP) were used for testing. The data was analyzed with SPSS 19.0 software, including an independent-samples t test and Spearman rank correlation. Results ①There was a negative correlation between the visual acuity of the amblyopic eye and (r=-0.298, P＜0.05). The confusion axis in the amblyopic patients distributed mainly in the blue and yellow sectors. ②There were no significant differences in the narrow time frame of P100 latencies between the L-dopa treatment group and the control group, except for the test based on red-gray (t=2.258, P＜0.05). There were no significant differences between the two groups in the increase of N75-P100 amplitudes, except for the tests based on black-white (t=2.642, P＜0.05), red-gray (t=2.861, P＜0.01), green-gray (t=2.526, P＜0.05), and red-green (t=2.281, P＜0.05). ③Excluding the effect of visual acuity on the CP-VEP, there were no significant differences in the narrow time frame of P100 latencies between the L-dopa treatment group and control group, except for the tests based on red-gray (t=2.113, P＜0.05) and green-gray (t=2.085, P＜0.05). There were no significant differences in the increase of N75-P100 amplitudes between the two groups, except for the tests based on black-white (t=2.531, P＜0.05), green-gray (t=2.229, P＜0.05) and red-green (t=2.374, P＜0.05). Conclusion There is a close relationship between CP-VEP latency and the amplitude of the change and the therapeutic effect when taking levodopa. Levodopa can improve partial color vision, but the specific mechanism is not clear.

Objective To evaluate the Spot vision screener for its testability and reliability of refractive data and its effectiveness in detecting refractive amblyopia risk factors in preschoolers. Methods This was a prospective study. One hundred forty-four children (mean age 3.0±1.2 years) were tested with Spot prior to an examination by a pediatric ophthalmologist. Agreement between screenings and cycloplegic refraction measurements were assessed using a t-test and a Pearson correlation for analysis. Sensitivity, specificity, positive predictive value, and negative predictive value for detection of refractive amblyopia risk factors were determined using the 2013 AAPOS vision screening committee referral guidelines. Results The Spot vision screener produced a computer printout result for 96.5% of the children, and provided refractive and eye position estimates in all computer printouts. Compared with cycloplegic retinoscopy, the device underestimated hyperopia or overestimated myopia (-1.32 D) and overestimated astigmatism(+0.39 D). The Pearson correlation coefficient for sphere and cylinder measures indicated good agreement between Spot and cycloplegic retinoscopy. Spot sensitivity was 90.9%, specificity was 82.1%, the positive predictive value was 48.8%, and the negative predictive value was 98% in detecting refractive amblyopia risk factors. Conclusion The Spot vision screener provides clinical data on a greater percentage of preschool children. The device is able to provide binocular refraction estimates and refractions with Spot agree more closely with cycloplegic refraction measurements. Spot is considered a useful device for screening refractive amblyopia risk factors.

Objective To investigate the criteria for vision and refraction screening in 2- and 3-year-old children. Methods This was a cross-sectional study of 3 804 children (7 656 eyes) aged 2 and 3 years old from kindergartens in the Haidian district who were selected for vision testing and refractive measurement． Distance vision was tested by the child symbols chart and refraction was measured with the Welch Allyn SureSight with noncycloplegy． Medians M (P25, P75) were used to describe visual acuity and refraction． The children were divided into seven groups based on their sphere and cylinder refraction and the distribution of refraction results was compared between any two groups. Visual acuity lower than 0.4 was considered abnormal. The incidence of abnormal vision in different groups was compared. The children were divided into three groups according to their refraction: normal vision ≥0.6; low vision=0.5; abnormal vision≤0.4, then an analysis of the incidence of refractive error in different vision groups was performed. Comparison of visual acuity in different refractive groups using rank sum test; the incidence of visual acuity and refractive abnormalities was compared using chi square test. Results The M (P25, P75) values for visual acuity were 0.6(0.6, 0.6) in 2-year-olds and 0.6(0.6, 0.8) in 3-year-old children. The visual acuity of 3-year-old children was higher than that of 2-year-old children and the difference was statistically significant(Z=-10.10, P<0.01). However, the difference was not significant for sphere and cylinder refraction (Z=-2.48, -2.10, P>0.05). There was a statistically significant difference for sphere refraction(χ²=89.22, P<0.01). The visual acuity in the 3.00 D or more group was lower (Z=3.53, P<0.01) than the overall sample; the visual acuity in the -0.25～+0.75 D group was significantly better (Z=1.66, P<0.05) than the overall sample. The differences in visual acuity between +1.00～+2.75 D group and the overall sample were not statistically significant (Z=0.44, P>0.05); while the +3.00 D or more group was significantly lower (Z=3.53, P<0.01). The difference was statistically significant among different cylinder refractions(χ²=373.73, P<0.01). The visual acuity between group 0.00～-1.50 D and the overall sample was not significantly different (Z=1.02, P>0.05). When the cylinder was -1.75 D or higher, visual acuity was significantly lower than normal levels (Z=3.31, 4.73, 4.97, P<0.01). When the sphere was higher than +3.00 D and the cylinder was more than -1.75 D, then the abnormal rate of visual acuity was significantly higher than normal levels (χ²=142.20, P<0.01). The abnormal rate of refraction was also significantly higher in the group with abnormal vision(χ²=240.82, P<0.01). Conclusion Refraction screening of 2- and 3-year-old children is helpful in detecting amblyopia early. The criteria for refraction screening: sphere +3.00 D or higher and cylinder -1.75 D or more.

Objective To investigate refractive surgery on new recruits in the Chinese People’s Liberation Army Navy in 2014 in the Qingdao north China sea fleet, as well as to provide a reference for the design of a vision monitoring system. Methods This was a cross-sectional study. A total of 1990 new recruits in the Chinese People’s Liberation Army Navy in the north China sea fleet were interviewed and underwent routine examinations for visual acuity, intraocular pressure, refraction and slit-lamp microscopy. Patients were divided into low myopia group and media high myopia group according to preoperative spherical equivalent, and ≤6 months group and >6 months group according to postoperative time. The differences in the sample rate between the two groups were analyzed with a chi-square test. Results All 1990 new recruits came from 12 provinces and direct-controlled municipalities. A total of 210 new recruits (10.55%) had undergone LASIK surgery before joining the army. The surgical procedures included 154 cases of LASIK (73.3%), 28 cases of LASEK (13.3%), 24 cases of femtosecond LASIK (11.4%), 3 cases of SMILE (1.5%) and 1 case of ICL (0.5%). Postoperative complications included reading fatigue in 33 cases (15.7%), diminution of night vision in 15 cases (7.1%) and glare in 10 cases (4.7%), double image in 8 cases (3.8%), and dry eye in 43 cases (20.5%). There were statistically significant differences in postoperative complications between the low myopia group and the moderate and high myopia groups (χ²=5.339, 5.271, 4.508, 6.117, P<0.05). There were statistically significant differences between the ≤6 months group and the >6 months group in diminution of night vision, reading fatigue and dry eyes (χ²=3.940, 4.516, 5.418, P<0.05). There were no statistically significant differences between the ≤6 month group and the >6 month group in diminution of night vision and glare (χ²=0.606, 0.609, P>0.05). Conclusion The recruits′ postoperative complications are related to preoperative refractive error and amount of time since surgery. The visual standard of recruits for visual acuity, degree of myopia and the time line since surgery should be adjusted.

Objective To investigate the visual rehabilitation needs of low vision patients and the potential reasons for low vision rehabilitation refusals in order to develop practical policies for more successful delivery of low vision rehabilitation. Methods A retrospective study was conducted of the records of 361 patients who had visited the Center of Excellence in Low Vision & Vision Rehabilitation in Eye Hospital of Wenzhou Medical University, from July 2013 to July 2014. Reviewed parameters included age, gender, patients source, cause of visual impairment, the percentage of visual impairment, visual rehabilitation goals, rehabilitation service ratio, low vision aids (LVAs) acceptance ratio and the reasons for refusing low vision rehabilitation. Of all 361 subjects (193 males, 168 females), aged from 3 to 92 years, mean of 44.2±23.0 years, 68.5% were referred by other departments at this hospital. Results The two major causes of visual impairment were congenital cataract (30.7%) and nystagmus (28.0%) in 3-19 year olds and pathological myopia (25.5%) and other retinal diseases (25.2%) in the 20+ group. 88.2% of the patients had low vision rehabilitation needs. There were two dominant needs cited for improving vision. The most dominant need for distance vision was to improve visual acuity for entertainment. The most dominant need for near vision was also to improve visual acuity for entertainment, but the second most important need was to improve reading. LVA acceptance ratio was 59.4%. Patients refused treatment because they hoped to get help from other medical treatments (93.6%). Conclusion The most common visual rehabilitation need of patients in our low vision clinic is to improve visual acuity for entertainment. The development of low vision rehabilitation strategies for entertainment may be the most efficient and effective means of rehabilitation.