Influence of Peripheral Visual Signals on Emmetropization of Infant Rhesus Monkeys / 中山大学学报(医学科学版)

[Objective]To investigate the effects of peripheral form-deprivation and central form-deprivation on em-metropization of infant rhesus monkeys.[Methods]Nineteen healthy infant rhesus monkeys,about 3 weeks of age,were divided into three groups of A(n=6),B(n=6)and C(n=7)by random.The monkeys from group A wore peripheral form-deprivation spectacle lenses over both of their eyes.The monkeys from group B wore central form-deprivation lenses over both of their eyes.The monkeys from group C were 0.00 Dlenses over both of their eyes as control.The monkeys'refractive error,corneal topography,vitreous chamber depth were measured at the start of lens wear and at 2 weeks,1.5 months, 2 months,3 months post-treatment. By these means,we can observe the changes of eye growth and refractive status dynamically.[Results]In group A,B and C,no statistically significant difference was observed between the right and left eyes in vitreous chamber depth and refractive errors pre-and post-treatment(P>0.05).During the course of study,the vitreous chamber depthelongated gradually and refractive status became less hyperopic in all animals.After 3 months'lens wear,the axial eyeball elongation amplitude(mm)of group A(peripheral form-deprivation group,1.25±0.36)monkeys was more obvious than that of group C(control group,0.55±0.19,P=0.001),but there was no statistically significant difference between group B(0.59±0.14)and C(P=0.807).The decrease of hyperopic degrees(D)of group A monkeys (-4.44±1.33)was more obvious than that of group C(-1.83±0.58,P=0.000).The eyes of group A monkeys appeared a remarkable myopic shift after treatment. No statistically significant difference was found between group B(-2.25±0.31) and C in hyperopic degrees reduction(P=0.383). Before and after lens wear,no statistically significant difference was found within or between groups in corneal Sim K values(P>0.05).[Conclusion]During the emmetropization process of infant rhesus monkeys,if the visual signals from peripheral retina are in conflict with those from central retina,the former will play a dominant role.

Macular edema in Asian Indian premature infants with retinopathy of prematurity: Impact on visual acuity and refractive status after 1‑year.

Purpose: To report the impact of transient, self‑resolving, untreated “macular edema” detected on spectral domain optical coherence tomography in Asian Indian premature infants with retinopathy of prematurity (ROP) on visual acuity (VA) and refraction at 1‑year of corrected age. Materials and Methods: Visual acuity and refraction of 11 infants with bilateral macular edema (Group A) was compared with gestational age‑matched 16 infants with ROP without edema (Group B) and 17 preterms infants without ROP and without edema (Group C) at 3, 6, 9 and 12 months of corrected age using Teller Acuity Cards and cycloplegic retinoscopy. Sub‑group analysis of the previously described pattern A and B macular edema was performed. Results: Visual acuity was lower in infants with macular edema compared with the other two control groups throughout the study period, but statistically significant only at 3 months. Visual improvement in these infants was highest between the 3rd and 6th month and plateaued by the end of the 1st year with acuity comparable to the other two groups. The edema cohort was more hyperopic compared to the other two groups between 3 and 12 months of age. Pattern A edema had worse VA compared to pattern B, although not statistically significant. Conclusion: Macular edema, although transient, caused reduced VA as early as 3 months of corrected age in Asian Indian premature infants weighing <2000 g at birth. The higher hyperopia in these infants is possibly due to visual disturbances caused at a critical time of fovealization. We hypothesize a recovery and feedback mechanism based on the principles of active emmetropization to explain our findings.

Long-Term Changes of Hyperopic Refractive Error in Refractive Accommodative Esotropia

PURPOSE: To analyze the long-term changes of hyperopic refractive error in patients with refractive accommodative esotropia. METHODS: We retrospectively reviewed the medical records of 54 patients with accommodative esotropia who underwent at least 36 months of follow-up and had hyperopia more than +1.50 diopter (D). The patients were divided into groups according to the degree of hyperopia: +1.50~ or =+3.00~ or =+5.00 D, the age of their first hyperopic glasses prescription: under two-years old, between two to four-years old and older than four years old, whether or not they had amblyopia, the degree of astigmatism: or =0.75- or =1.25 D and divided into two groups according to the degree of stereopsis: 400 sec. The divided groups were than retrospectively reviewed if they influenced the refractive error at the third year of follow-up using Fisher's exact test, paired t-test, Wilcoxon's signed-ranks test, Mann-Whitney U test, Kruskal-Wallis H test, and ANOVA (p < 0.05). RESULTS: The mean follow-up period was 103.72 +/- 41.82 months for refractive accommodative esotropia. Patients with a greater initial hyperopic refractive err or showed a significant tendency towards emmetropization with a higher rate of hyperopic decrease (p < 0.001), regardless of the hyperopic refractive error. Statistical differences were not observed in patients who started wearing glasses after four-years old, patients with amblyopia, patients with a large degree of astigmatism, and patients with poor stereoacuity. CONCLUSIONS: Long-term changes of hyperopic refractive error in accommodative esotropia showed a significant decrease when initial hyperopic refractive error was high. Wearing hyperopic glasses at an older age and visual functions such as amblyopia, large degree of astigmatism, and poor stereoacuity may influence emmetropization.

Normal development of refractive state and ocular dimensional components in guinea pigs / 吉林大学学报(医学版)

Objective To study the emmetropization in guinea pig eyes during the normal development from birth in order to provide theoretical basis to use guinea pigs as model for research on near-sightedness.Methods Sixty-four guinea pigs were assigned to 8 groups (n=8,4 male/4 female).Each group underwent a series of ocular examinations at one of the 8 time-points (0,1,2,3,5,7,9 and 11 weeks),including refraction(R),radius of corneal curvature (RCC),depth of anterior segment(AS),thickness of crystalline lens (CL),length of vitreous chamber (VC)and axial length (AL).Pooled results from both eyes of the same animals with mixed sexes can be used for further assessment of the emmetropization with the associated biometrical changes of the eye.Correlations were made between RCC,AS,CL,VC,AL and R. Results There were no significant differences between the right eye and left eye or between male and female in results of all the examinations. The refraction at birth was (+5.25?0.22 )D in guinea pigs.This value rapidly decreased during the first 3 weeks,approaching(+1.34?0.61) D by 11 weeks.There was no significant difference in refraction between 9 and 11 weeks (P= 0.215). The RCC was (3.23?0.01) mm at birth,AS was (1.20?0.00) mm at birth,CL was (2.72?0.02) mm at birth and VC was (3.27?0.01) mm at birth,they increased within the first 3 weeks despite a transient decrease in the RCC within the first week.Such an increase continued except the AS which became constant after 3 weeks.The VC was more correlated to the emmetropization (r=-0.818,P

Long-term Follow-up Results of Hyperopic Refractive Change

PURPOSE: To investigate the trend of refractive change in hyperopic patients according to increases in age. METHODS: Eighty-eight children who had hyperopia of more than +1.50 diopters (D) and could be followed up for at least 5 years were included in this study. We divided the patients into two groups according to the level of initial hyperopia and retrospectively analyzed hyperopic refractive changes over a 5-year period according to age at initial diagnosis, presence of esotropia, amblyopia, astigmatism and anisometropia. RESULTS: We gained the following formula about the aspect of hyperopic reduction in 88 patients over a period of 5 years: Diopter (D)=7.99-2.14 Ln (age). The presence of anisometropia and amblyopia did not affect hyperopic reduction. Hyperopic reduction amounts in the group with a hyperopic eye of more than +5D at initial diagnosis were greater than in the group with a hyperopic eye less than +5D, and greater in the group with an astigmatic eye of more than 1D. The presence of esotropia and the age at initial diagnosis did not affect hyperopic reduction. CONCLUSIONS: We show that emmetropization in hyperopic children occurs according to the following formula: Diopter (D)=7.99-2.14 Ln (age). Both the initial level of hyperopia and the concurrent presence of astigmatism affected hyperopic reduction. However, the presence of anisometropia, amblyopia, esotropia and the age at initial diagnosis did not significantly affect hyperopic reduction.

Long-term Observations on the Emmetropization of the High Hyperopia

PURPOSE: We are to investigate the reduction rate of high hyperopia, that is, process of emmetropization. METHODS: Thirty children who had hyperopia more than spherical equivalent of+4.0 diopter and could be followed at least 3 years were reviewed retrospectively. Data including visual acuity and the magnitude of hyperopia were collected every 6 months from 3 years of age. Annual reduction rates of hyperopia were analysed. Changes in the level of hyperopia were compared with those who had strabismus or astigmatism and those who did not. RESULTS: The children who had higher degree of initial hyperopia showed the faster rates of annual reduction but also significantly higher level of remained hyperopia (p=0.003). The concurrent presence of astigmatism was associated with a lesser reduction in hyperopia (p=0.01). CONCLUSIONS: Our data show that, as a whole, the emmetropization of high hyperopia occurs as a linear function of the initial level and converges toward a low hyperopic value. We have also found that astigmatism might impede emmetropization.

The Effects of Illumination to Experimentally Induced Refractive Errors in the Chick

The effects of different luminance levels and light sources to emmetropization in the chick were investigaed. One-day-old, forty chicks were reared under condition of unilateral visual deprivation with translucent goggle. Under normal light cycles (12-h light/12-h dark), three kinds of luminance levels and two light sources (incandescent lamp vs fluorescent lamp) were used. Three weeks after hatching, refractive error, axial length, equator diameter and corneal diameter of the eyes were measured. The deprived eyes exhibited severe myopia of -11.94 diopters (p<0.001) and refractive changes were mainly related with axial elongations. Refractive error of 1000 lux group was less myopic than 2000 lux group (p<0.05). The fellow eyes didn't show significant difference between groups. No significant changes were noted between different light source groups. The experiment suggests that different degrees of illumination under normal light/dark environment can cause different refractive changes; More studies will be needed to show that the ideal luminance condition for emmetropization in our enviroment be present.