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AIM: To compare the accuracy of different intraocular lens(IOL)calculation formulas in cataract patients with axial length longer than 28mm and a history of radial keratotomy(RK).METHODS: Retrospective study. The medical records of 19 cataract patients(29 eyes)after RK and with axial length longer than 28mm who underwent cataract surgery from January 2011 to July 2020 in Beijing Tongren Hospital were analyzed. The absolute error(AE)of the difference among three different formulas was calculated. AE refers to the absolute value between the actual spherical equivalent after cataract surgery and the spherical equivalent predicted by the IOL formula. The AE values of the three formulas and the percentages of eyes with AE≤0.5, 0.75, 1.0, and 2.0D were calculated and compared.RESULTS: The AE values of the three formulas were significantly different(χ2=8.759, P=0.013). The Barrett True-K formula had the smallest median AE, which was only 0.62(0.20, 1.15)D, followed by the Haigis formula 0.76(0.34, 1.26)D, and the Holladay 1(D-K)formula had the largest 1.01(0.49, 1.62)D. The percentages of affected eyes with AE ≤0.5, 0.75, 1.0, and 2.0D for the Barrett True-K formula were 48%, 59%, 69%, and 93%, which were equal to or higher than the other two formulas.CONCLUSION: The Barrett True-K formula is more recommended among the three formulas for cataract patients after RK and with axial length longer than 28 mm.

AIM: To explore that double steep axial transparent corneal incision can effectively minimize corneal astigmatism and high-order aberration(HOA)in cataract patients with moderate to low degree corneal astigmatism, as well as improve postoperative visual quality.METHODS: A total of 60 cataract patients diagnosed with moderate to low corneal astigmatism in our hospital from October 2020 to July 2021 were randomly divided into group A(normal 135° incision, 30 cases)and group B(double steep axial transparent corneal incision, 30 cases). The uncorrected visual acuity(UCVA), astigmatism, astigmatism vector decomposition, polar keratometry(Polar K), second-order astigmatism, spherical, coma and trefoil aberration within 3mm of the central pupil were compared at 1 and 3mo before and after surgery.RESULTS: UCVA of group A and group B at 1 and 3mo after surgery was significantly higher than that before surgery(P0.05). The corneal astigmatism of group A at 1 and 3mo postoperative were not significantly different from that before surgery(P>0.05).The mean corneal astigmatism of group B was 0.66±0.13 and 0.61±0.12D at 1 and 3mo after surgery, respectively, which was significantly lower than the preoperative value of 1.38±0.24D(P0.05). In group A, CJ0/CJ45 were both significantly different from those at 1 and 3mo before surgery(P0.05). The coma aberration of group B at 3mo after surgery was lower than that before surgery and group A.CONCLUSION: For cataract patients with moderate to low corneal astigmatism, there was no significant difference in postoperative UCVA and HOA between double steep axial transparent corneal incision and normal incision. However, compared with normal incision, double steep axial transparent corneal incision can improve postoperative visual quality by effectively reducing corneal astigmatism and coma aberration.

AIM:To discuss the efficacy and safety of orthokeratology with reducing back optic zone diameter(5mm-BOZD)compared with conventional back optic zone diameter(6mm-BOZD)in the treatment of adolescent myopia.METHODS: A prospective randomized controlled trial was performed. There were 100 cases with 100 eyes of adolescent myopia(all right eye data were taken)selected from April 2016 to January 2019, the spherical degree was -1.00--5.00D. Then they were randomly divided into the two groups. The experimental group wore 5mm-BOZD orthokeratology, and the control group wore 6mm-BOZD orthokeratology. Their axis length(AL), spherical equivalent(SE), relative peripheral refraction(RPR), best corrected visual acuity(BCVA), uncorrected near visual acuity(NVA), Efron grading was applied to record the anterior segment of the eyes, corneal hysteresis(CH), corneal resistance factor(CRF), corneal-compensated intraocular pressure(IOPcc), average noninvasive Keratograph tear breakup time(NIKBUTav)and higher order aberration(RMSh) were compared between the two groups during the 1a treatment period.RESULTS: After 1a of treatment, the AL in experimental group increased 0.05±0.05mm,while it increased 0.15±0.05mm(t=-8.949, P0.05).CONCLUSION:Reducing back optic zone diameter orthokeratology can correct adolescent myopia safely and more effectively during the observation period.

AIM: To observe the epidemiological characteristics of myopia among primary school students in Xindu District of Chengdu before and after COVID-19 home isolation period(from Jan.-May 2020).METHODS:Cross-sectional study. A total of 10 153 primary school students from grade 1-6(age 6-13, three classes per grade)were selected from four primary schools in Xindu District of Chengdu for three consecutive years(2018-2020), by using a random stratified cluster sampling method. All students' visual acuity and spherical equivalent refraction(SE)were measured, a further cycloplegia optometry was conducted for those whose visual acuity was less than 5.0. The SE was recorded and the prevalence of myopia was calculated. Chi-square test was used to compare the difference of prevalence of myopia between different years. One-way Anova was used to compare the difference of SE among different years.RESULTS: There was statistical difference in prevalence of myopia between the three years(2018: 35.98%, 2019: 36.29%, 2020: 42.52%; χ2=39.374, P0.05).CONCLUSION: After the COVID-19 home isolation period, there was a significant myopic shift among students aged 6-9 years old. We should pay more attention to the window period for myopia prevention and control of 6-9 years old.

AIM: To observe the changes of tear film osmolarity(TFO)and inflammatory cytokines after wearing orthokeratology lens.METHODS: Prospective randomized controlled trial. Totally 79 cases of adolescent myopia(-1.00D to -5.00D)were selected from May 2016 to February 2019. Then they were randomly divided into the experimental group(39 cases)and the control group(40 cases). The experimental group wore orthokeratology lens, and the control group wore frame glasses. Their average noninvasive Keratograph tear breakup time(NIKBUTav), TFO, concentrations of IL-1β, IL-6, TNFα in tear samples were observed for 1a.RESULTS: NIKBUTav and TNFα after wearing orthokeratology lens for 6mo, 1a and stopping wearing for 4wk were different from that pre-wearing orthokeratology lens(P

AIM: To observe the changes of relative peripheral refraction(RPR)after wearing orthokeratology(OK)lens, and to explore the relationship between the changes of RPR and the axial length(AL).METHODS: Totally 104 cases of adolescent myopia(-1.00D to -6.00D)were selected from May 2016 to Nov. 2018. Then they were randomly divided into the experimental group and the control group. The experimental group wore OK lens, and the control group wore frame glasses. Their AL, RPR(N30°-T30°)were observed for 1a.RESULTS:The RPR of the experimental group showed myopic drift at each time point after wearing OK lens(P0.05). The RPR of the control group showed an increase in hyperopia. One year later, there were statistical differences in the changes of AL and RPR between the two groups(P

AIM: To observe the efficacy and safety of low-dose atropine eye drops combined with orthokeratology in the treatment of low and moderate myopia in adolescents.METHODS: Totally 126 cases of low and moderate myopia in adolescents(all right eye data, 126 eyes)who all wore orthokeratology lens for 1mo were selected from May 2016 to Aug 2018. Then they were randomly divided into the experimental group and the control group. The experimental group(63 eyes)was combined with low-dose(0.01%)atropine eye drops once a night, and the control group(63 eyes)was combined with polyethyleneglycol eye drops once a night. Their AL,SE, BCNVA,PD,AMP,BUT and IOP were observed. RESULTS: After 1y of treatment, the AL in the low myopia experimental group increased(0.13±0.03mm), while the low myopia control group increased(0.22±0.05mm). The AL in the moderate myopia experimental group increased(0.12±0.03mm),while the moderate myopia control group increased(0.20±0.05mm). The SE in the low myopia experimental group increased(0.16±0.07D), while the low myopia control group increased(0.21±0.08D). The SE in the moderate myopia experimental group increased(0.16±0.05D), while the moderate myopia control group increased(0.20±0.09D). There was statistical difference in AL and SE between the two groups(PP>0.05). But the pupil diameter of the experimental group was significantly larger than that of the control group. The accommodation amplitude of the experimental group was lower than that of the control group(PCONCLUSION: 0.01% atropine eye drops combined with orthokeratology can control the progression of myopia in adolescents more effectively, which is safe and effective.

AIM: To observe the adolescents with different degrees of myopia who wore orthokeratology lens for 1a were visited and discuss the influence and safety of orthokeratology for curing the adolescent myopia.METHODS: Totally 158 cases of adolescent myopia(-1.00D to -8.00D)who all wore the same brand orthokeratology lens were selected from September 2016 to December 2017. Their visual quality, including aberration detection, subjective discomfort and visual quality questionnaire was observed for 1a. RESULTS: After wearing orthokeratology, the patients' total RMS decreased, while the RMSh, the RMS3(including coma)and the RMS4(including spherical aberration)increased. The higher of baseline degree, the higher incidence of subjective visual discomfort, and the difference between pre-wearing and after was not statistically significant in subjective visual quality score(P>0.05).CONCLUSION: The patients' objective visual quality decreased after wearing orthokeratology lens. However, the long-term observation revealed that the overall visual quality had no significant impact on lifelihood and learning, which indicates orthokeratology is a safe and effective mean of myopia curing.

AIM:To investigate the prevalence of myopia among primary school students in Xindu district of Chengdu, and analyze the epidemiological characteristics and related influencing factors. METHODS: By means of stratified cluster random sampling survey, the first to sixth grade students from 4 primary schools in Xindu district of Chengdu were selected for ophthalmology examination and questionnaire survey, and the statistical analysis was carried out with SPSS21.0 software. RESULTS: There were 3 324 students participated in the survey, 1 124 students with myopia, and the prevalence rate of myopia was 33.81%. The single factor analysis of myopia found that different genders, different ages, different grades, eating fruits and vegetables and drinking milk frequency, parents supervise and remind students to use eye habits frequently, reading and writing light at home, continuous homework and reading time, sleep time, extracurricular activity time, frequency of going outdoors or doing eye exercises during recess, lying reading or reading in a wobbly car. The prevalence of myopia was different among the students with reading and writing posture and their parents with myopia, and the difference was statistically significant. The difference is statistically significant(PCONCLUSION: Juvenile myopia is related to many factors such as environment, heredity and so on. It is necessary to take appropriate measures as soon as possible to prevent its occurrence and development.

AIM:To study the refraction status in 354 amblyopia children and to investigate the related influence factors for the treatment effect. METHODS:Three hundred and fifty-four children diagnosed as ametropia amblyopia from January 2010 to June 2015 in our hospital were selected. The children were divided into groups according to the children's age, refraction types of amblyopia and degree of amblyopia. The clinical treatment effect of different groups was compared. RESULTS:The cure rate for amblyopia children in different groups was significantly different(PPPCONCLUSION:The treatment effect of ametropia amblyopia is correlated with the children's age, types of amblyopia and degree of amblyopia. It has a poor treatment effect for the older children with severe myopia and amblyopia.