Impact of Corneal Toricity on the Distribution of Corneal Epithelial Thickness.

PURPOSE: To investigate the impact of corneal toricity on the distribution characteristics of corneal epithelial thickness (CET). METHODS: A total of 330 eyes in 330 healthy participants were included in this study. They were divided into two groups based on the median of the corneal toricity value: low-toricity group (corneal toricity < 1.50 diopters) and high-toricity group (corneal toricity ≥ 1.50 diopters). The CET within a 9-mm-diameter area of the central cornea was obtained using optical coherence tomography. The difference of CET value between flat and steep meridians (F-S CET) was defined to evaluate the CET distribution. The F-S CET between the two groups was compared, and the correlations between F-S CET and the corneal toricity were analyzed. RESULTS: The CET was thinner in the superior-peripheral area than in other areas. A slight intergroup difference was noted in terms of the F-S CET at the paracentral (0.11 ± 0.93 vs 0.32 ± 0.92, P = .038), midperipheral (0.45 ± 0.78 vs 0.77 ± 0.89, P = .001), and peripheral (3.11 ± 2.18 vs 4.10 ± 2.38, P < .001) zone. In each zone, the difference in F-S CET between the two groups was less than 1 µm. As the area expanded, the F-S CET continued to increase (F = 850.303, P < .001). A weak correlation was observed between F-S CET and corneal toricity (r = 0.103 to 0.240); however, this correlation was not significant in the paracentral zone. Covariance analysis demonstrated that F-S CET was slightly correlated with age, refractive state, and intraocular pressure. CONCLUSIONS: The corneal toricity did not significantly affect the distribution of the corneal epithelium in normal corneas. [J Refract Surg. 2023;39(7):482-490.].

Two-year stability of posterior corneal surface after transepithelial photorefractive keratectomy with a residual stromal thickness less than 350 µm.

PURPOSE: This study aimed to investigate the stability of posterior corneal surface 2 years after transepithelial photorefractive keratectomy (TPRK) in patients with a residual stromal thickness less than 350 µm. METHODS: In total, 408 eyes of 212 patients (160 women, 52 men) who underwent TPRK were enrolled in this retrospective study. All surgeries were performed in the Amaris 750S excimer laser platform with smart pulse technology. The posterior corneal elevation, anterior chamber depth, Q value, and curvature were measured using Pentacam preoperatively and postoperatively. All patients were followed up for 2 years. The relationship between percent tissue altered (PTA), age, and changes in posterior corneal surface was analyzed. RESULTS: The mean preoperative spherical equivalent was - 6.80 ± 1.18 D (range: - 9.00 to - 2.63 D). The mean residual stromal thickness was 336.46 ± 7.25 µm (range: 310-348 µm). The mean PTA was 30.93 ± 2.03% (range: 24.29-35.28%). At 2 years after surgery, the elevation of six points in the central area decreased by 1.91 ± 2.97 µm, 2.98 ± 3.23 µm, 1.17 ± 3.85 µm, 1.70 ± 2.88 µm, 1.36 ± 3.19 µm, and 1.65 ± 3.18 µm, compared with the preoperative value (P < 0.05). The elevation of three points in the peripheral area increased by 1.87 ± 6.34 µm, 0.68 ± 6.00 µm, and 0.95 ± 5.50 µm (P < 0.05). There was no significant linear relationship between PTA, age, and changes in posterior corneal surface, anterior chamber depth, and K2 (all P > 0.05). CONCLUSION: Within 2 years after TPRK, the posterior corneal surface remained stable in patients with a residual stromal thickness between 310 and 350 µm. There was no sign of iatrogenic ectasia during the follow-up period.

Role of corneal epithelial thickness during myopic regression in femtosecond laser-assisted in situ keratomileusis and transepithelial photorefractive keratectomy.

BACKGROUND: The study aimed to investigate the relationship between changes in corneal epithelial thickness and the outcome of myopic regression after femtosecond laser-assisted in situ keratomileusis (FS-LASIK) and transepithelial photorefractive keratectomy (TPRK). METHODS: This study included 45 eyes of 25 patients undergoing FS-LASIK and 44 eyes of 24 patients undergoing TPRK. Myopic regression occurred in these patients postoperatively from 8 to 21 months. The corneal epithelial thickness was measured using a spectral-domain optical coherence tomography at the onset of regression, 3 months after treatment, and 3 months after drug withdrawal. RESULTS: Compared with that of preoperation, corneal epithelial thickness increased when regression occurred in both groups (all P < 0.05). The thickness of central corneal epithelium in FS-LASIK and TPRK groups reached 65.02 ± 4.12 µm and 61.63 ± 2.91 µm, respectively. The corneal epithelial thickness decreased when myopic regression subsided after 3 months of steroid treatment compared to the onset (P < 0.05). With a decrease in corneal epithelial thickness, the curvature of the anterior corneal surface, central corneal thickness, and refractive power all decreased (all P < 0.05). The corneal epithelial thickness and refractive error remained relatively stable after 3 months of treatment withdrawal (P > 0.05). CONCLUSION: The corneal epithelial thickness determined the outcome of myopic regression similarly in FS-LASIK and TPRK. When the corneal epithelium thickened, regression occurred. After steroid treatment, epithelial thickness decreased whereas regression subsided.

Comparison of wavefront-optimized and corneal wavefront-guided transPRK for high-order aberrations (>0.35 µm) in myopia.

PURPOSE: To compare the clinical outcomes, mainly including contrast sensitivity and high-order aberrations (HOAs), between wavefront-optimized (WFO) and corneal wavefront-guided (CWFG) transepithelial photorefractive keratectomy (transPRK) for preoperative HOAs >0.35 µm. SETTING: Qingdao Eye Hospital of Shandong First Medical University, Qingdao, Shandong, China. DESIGN: Prospective randomized controlled study. METHODS: 71 patients with preoperative total ocular and corneal aberrations >0.35 µm who underwent transPRK for the treatment of myopia and myopic astigmatism were randomly divided into the aberration optimization mode group (WFO group; 36 eyes) and the corneal wavefront-guided mode group (CWFG group; 35 eyes). Preoperative and postoperative visual outcome, refraction, contrast sensitivity, and HOAs were compared. RESULTS: 71 patients (71 eyes) who underwent transPRK were selected. The CWFG group had significantly lower total HOAs and coma values in the corneal aberration compared with the WFO group at 3 ( P = .009; P < .001) and 6 months postoperatively ( P = .006; P < .001). In addition, the CWFG group had significantly lower total HOAs and coma values in the whole-eye aberration compared with the WFO group at 3 ( P = .044; P = .004) and 6 months postoperatively ( P = .026; P = .001). The CWFG group had significantly better improvement in contrast sensitivity than the WFO group at spatial frequencies of 3 cycles per degree (cpd), 6 cpd, 12 cpd, and 18 cpd ( P = .005, P = .007, P = .001, and P < .001, respectively). CONCLUSIONS: CWFG transPRK is associated with better visual and refractive outcomes and less HOAs than WFO transPRK in eyes with preoperative aberrations >0.35 µm.

Comparison of efficacy of two different silicone hydrogel bandage contact lenses after T-PRK.

AIM: To compare the efficacy between two different silicone hydrogel bandage contact lenses after transepithelial photorefractive keratectomy (T-PRK). METHODS: In this randomized controlled trial, a total of 89 patients (178 eyes) who underwent T-PRK at the Qingdao Eye Hospital from October to December 2019 were selected. One random eye wore a Senofilcon A bandage contact lens after surgery, and the other eye a Balafilcon A bandage contact lens. Pain scores, uncorrected visual acuity (UCVA), spherical equivalent (SE), corneal epithelial healing status, epithelial thickness, bandage lenses deposits, lenses movement, and ocular surface conditions were measured and compared. RESULTS: There were no differences between the two groups in UCVA, SE, corneal epithelial healing status, corneal epithelial thickness, tear river heights and tear film rupture time at each follow-up visit. However, postoperative pain scores in the Senofilcon A group were significantly lower than those of the Balafilcon A group (F intergroups=67.833, P<0.001; F time=383.773, P<0.001; F interaction=57.344, P<0.001). The duration of pain in eyes in the Senofilcon A group was shorter than that of the Balafilcon A group (t=-3.326, P=0.001). The surface deposition scores and movement scores of Senofilcon A bandage lenses on the first and fourth days after surgery were lower than those of Balafilcon A bandage lenses (Z=-5.385, -6.782, P<0.001; Z=-8.336, -8.906, P<0.001). CONCLUSION: Both Senofilcon A and Balafilcon A bandage lenses have good efficacy after T-PRK. Senofilcon A lenses are associated with less pain and more comfort compared to Balafilcon A.

Agreement and Repeatability of Central and Peripheral Refraction by One Novel Multispectral-Based Refractor.

Purpose: To evaluate the repeatability of a multispectral-based refractor in central and peripheral refraction measurement, and to assess the agreement of such measurements with objective refraction (OR) and subjective refraction (SR) in patients with myopia. Methods: A total of 60 subjects were recruited in this prospective research. Patients were divided into three groups according to the refractive error. Next, the central and peripheral refraction parameters were measured using multispectral refractive tomography (MRT) before and after cycloplegia. In addition, OR and SR measurements were also performed. The intraobserver repeatability was analyzed using within-subject standard deviation (Sw), test-retest repeatability (TRT), and intraclass correlation coefficient (ICC). Agreement was evaluated using Bland-Altman plot and 95% limits of agreement (LoA). Results: The ICC value of central and peripheral refraction were all higher than 0.97 with or without cycloplegia. The peripheral refraction in the nasal, temporal, superior, and inferior quadrants was slightly worse than other parameters, with the largest error interval being 1.43 D. The 95% LoA of the central refraction and OR or SR ranged from -0.89 to 0.88 D and -1.24 to 1.16 D without cycloplegia, respectively, and from -0.80 to 0.42 D and -1.39 to -0.84 D under cycloplegia, respectively. Conclusions: The novel multispectral refraction topography demonstrated good repeatability in central and peripheral refraction. However, the refraction in the nasal, temporal, superior, and inferior quadrants were not as good as that of central and circle peripheral refraction.

Effect of Sunshine Duration on Myopia in Primary School Students from Northern and Southern China.

BACKGROUND: To assess the current myopia prevalence rate and evaluate the effect of sunshine duration on myopia among primary school students in the north and south of China. METHODS: This prospective cross-sectional study pooled data from 9171 primary school students (grades from 1 to 6) from four cities in the north and south of China. National Geomatics Center of China (NGCC) and China Meteorological Administration provided data about altitude, latitude, longitude, average annual temperature, and average annual sunshine duration. Non-cycloplegic refraction was recorded, and prevalence rates in primary school students and factors associated with myopia were analyzed. Univariate and multivariate logistic regression models were used to determine the independent association of risk factors of myopia. RESULTS: The overall myopia prevalence was 28.0%, from 7.5% to 50.6% for first and sixth grades, respectively. Low, moderate and high myopia significantly increased with school grades from 7.30% to 35.0%, 0.3% to 13.60% and 0.00% to 1.9%, respectively. Multiple regression analysis revealed that longer average cumulative daylight hours were connected to lower myopia prevalence in primary school students (OR, 0.721; 95% CI, [0.593-0.877]; P=0.001), whereas girls and higher grade was independently associated with higher myopia prevalence (girls: ß=0.189; OR, 1.208; 95% CI, [1.052-1.387]; P=0.007; higher grade: ß=0.502; OR, 1.652; 95% CI, [1.580-1.726]; P<0.001). CONCLUSION: This study demonstrated that myopia was highly prevalent in southern Chinese cities over northern ones, linked to shorter light exposure, higher education level, and female gender. Such findings reinforced the beneficial impact of daylight exposure with a protective role against myopia development.

The impact of cataract progression on accuracy of intraocular lens power measurement.

PURPOSE: The aim of this study was to assess the impact of cataract progression using the Haigis formula-calculated intraocular lens (IOL) power and investigate the accuracy of IOL power measured at different time points. METHODS: This prospective study was performed on 75 eyes of 75 patients who underwent uneventful cataract surgery. Preoperative ocular parameters including axial length (AL), keratometry (K), anterior chamber depth (ACD), corneal astigmatism, corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA) examined at the two time points, more than 3 months preoperatively and preoperative 1 day were compared. The ocular parameters measured in the two time points were used to calculate the predicted implanted IOL power and the actual IOL power was chosen on the basis of parameters measured earlier before surgery using the Haigis formula. The mean numerical error (MNE) and mean absolute error (MAE) predicted by the two time points were also compared. RESULTS: There were significant differences in the ACD, IOL power, UDVA and CDVA (P<0.01), but no statistical differences in AL, mean K and corneal astigmatism (P>0.05) during the average of 5.6 months before surgery. No statistically significant difference was detected in MNE (P>0.05), while the MAE had a significant difference in the two time points (P<0.05). CONCLUSION: The IOL power measured earlier before surgery might result in a higher accuracy and the postoperative refractive outcome tended towards emmetropia.

Comparison of clinical results between trans-PRK and femtosecond LASIK for correction of high myopia.

BACKGROUND: To compare the clinical outcomes of transepithelial photorefractive keratectomy (TPRK) with femtosecond laser-assisted in situ keratomileusis (FS-LASIK) for correction of high myopia. METHODS: In this prospective, non-randomised, cohort study, 85 eyes of 46 patients treated with TPRK and 80 eyes of 42 patients treated with FS-LASIK were included. All eyes were highly myopic (spherical equivalent refraction <- 6.00 diopters). Both TPRK and FS-LASIK were performed by Schwind Amaris 750S excimer laser. Visual acuity, refraction, corneal high order aberration (HOA) and other variables were analyzed before and at 1, 3, 6, 12 months after surgery. RESULTS: At 12 months after surgery, uncorrected logMAR distance visual acuity (UDVA) in the TPRK and FS-LASIK groups was - 0.04 ± 0.04 and - 0.01 ± 0.08, respectively (P = 0.039). Corrected logMAR distance visual acuity (CDVA) was - 0.06 ± 0.05 and - 0.04 ± 0.05 in both groups (P = 0.621). For UDVA, 86% of eyes in the TPRK group and 80% in the FS-LASIK group remained unchanged or improved one or more logMAR lines (P = 0.314), compared to preoperative CDVA. For CDVA, 97% of eyes in the TPRK group and 90% in the FS-LASIK group remained unchanged or improved one or more lines (P = 0.096), compared to preoperative CDVA. Spherical equivalent refraction was - 0.05 ± 0.39 and - 0.26 ± 0.47 in both groups (P = 0.030). 87% of eyes in the TPRK group and 73% in the FS-LASIK group achieved ±0.50 D target refraction (P = 0.019). All 85 eyes (100%) in the TPRK group and 75 eyes (92%) in the FS-LASIK group were within ±1.00 D of target (P = 0.003). Root mean square (RMS) of corneal total HOA and vertical coma in the TPRK group were lower compared with the FS-LASIK group (P < 0.001 for both variables). CONCLUSIONS: TPRK and FS-LASIK showed good safety, efficacy and predictability for correction of high myopia. Clinical outcomes of TPRK were slightly better than FS-LASIK.

Associated factors of screened myopia of junior middle school students in six provinces of China / 中国学校卫生

Objective@#To understand the current situation and associated factors of myopia in junior middle school students, and to provide scientific basis for prevention and control of myopia in junior middle school students.@*Methods@#A total of 5 393 junior middle school students were selected from middle schools in Guangdong, Guangxi, Guizhou, Liaoning, Shandong, Shanxi provinces. The visual acuity of middle school students was examined, and the data of general population, economy, sociology and natural environment were obtained through statistical yearbook of each province. The influencing factors of myopia of middle school students were analyzed by univariate and multivariate Logistic regression.@*Results@#The results of single factor analysis showed that the myopia rate of junior high school students was different by gender, grades, parents average wage, sunshine duration, temperature, altitude, longitude and latitude(χ2=47.76，59.05，10.79，106.19，53.56，85.02，76.23，107.07，P<0.05). The results of multi factor analysis showed that gender, grade, average wage, temperature and latitude was positively associated with myopia vision; sunshine duration and longitude were negatively associated with the risk for myopia(OR=1.54，1.34，1.62，7.58，27.10，0.42，0.39，P<0.05).@*Conclusion@#The myopia of junior high school students is affected by a variety of factors, economic and social factors and natural environmental factors have an impact on the screening of sexual myopia in junior high school students. Economic and social factors and natural environmental factors should be taken into account in the formulation of myopia prevention and control measures.

Analysis of influencing factors of screened myopia in primary school students in seven provinces / 中国学校卫生

Objective@#To understand the current situation and associated factors of myopia among primary school students, and to provide scientific basis for prevention and control of myopia among primary school students.@*Methods@#In Gansu, Guangdong, Guangxi, Guizhou, Liaoning, Shandong, Shanxi and other provinces, 1 prefecture was selected, and a number of primary schools were selected from each region. All the students in the class were selected as the object of this survey. A total of 8 365 middle school students were examined for their eyesight, and the data of general population economic indicators and natural environment indicators were obtained through the statistical yearbook of various provinces and cities. The influencing factors of primary school students myopia were analyzed by chi-square test and multivariate Logistic regression.@*Results@#Univariate analysis showed that different provinces and different sex, different nationalities, different grade, parents average salary, sunshine duration, air temperature, altitude, longitude, latitude, different economic zone(χ2=116.22, 18.08, 26.33, 1 059.04, 14.86, 10.28, 16.95, 10.01, 23.15, 29.43, 88.14, P<0.05). Multivariate analysis results showed that gender, grade, sunshine duration, longitude were risk factor for poor vision(OR=1.31, 1.71, 1.45, 1.54, P<0.05); Economic zone and parents salary were protective factors for poor eyesight of students (OR=0.65, 0.86, P<0.05).@*Conclusion@#Myopia of primary school students is affected by a variety of factors, economic and social factors and natural environmental factors have an impact on the screening.

Effects of dopaminergic agents on progression of naturally occurring myopia in albino guinea pigs (Cavia porcellus).

PURPOSE: Disruption of dopaminergic signaling has been implicated in the abnormalities of ocular development in albinism, and many experiments have shown that retinal dopamine is a major regulator of postnatal eye growth and myopia in animal models. Therefore, in the present study we investigated whether progressive myopia, which can occur in albino guinea pigs without experimental manipulation of visual conditions, is affected by dopaminergic agents. METHODS: Two-week-old albino guinea pigs, selected for being myopic (range refractive error [RE], -2 to -10 diopters [D]), received unilateral peribulbar injections of apomorphine (nonselective dopamine receptor agonist; 0, 7.5, 25, 75, 250, 750, and 2500 ng; n = 112), SKF38393 (D1-like agonist; 0, 10, 100, 1000 ng; n = 63), SCH23390 (D1-like antagonist; 0, 2500 ng; n = 27), quinpirole (D2-like agonist; 0, 10, 100, 1000 ng; n = 58), or sulpiride (D2-like antagonist; 0, 2500 ng; n = 24) once a day for four weeks. One noninjected group (n = 19) served as untreated control. Refractive states and axial dimensions of the eyes were measured without cycloplegia or general anesthetic, using eccentric infrared photoretinoscopy and A-scan ultrasonography, respectively, before treatment, and after 2 and 4 weeks of treatment. The main drug effects were analyzed by paired t-test or 2-way repeated measures ANOVA, as required. RESULTS: The naturally occurring progression of myopic RE was inhibited by apomorphine at relatively high doses (250 and 750 ng), SKF38393 at 100 ng (D1-like agonist), and sulpiride at 2500 ng (D2-like antagonist), but promoted by apomorphine at a lower dose (25 ng), quinpirole at 100 ng (D2-like agonist), and SCH23390 at 2500 ng (D1-like antagonist). All drugs affected primarily vitreous chamber depth, rather than anterior segment dimensions. CONCLUSIONS: Our data suggest that the activation of D1-like receptors inhibits, whereas activation of D2-like receptors promotes, progressive myopia in this animal model. The robust effects of antagonists suggest that ocular dopamine receptors in these albinos may be in a chronic state of partial excitation. The precise location and identity of the receptors responsible for these effects remain to be determined.

Disruption of emmetropization and high susceptibility to deprivation myopia in albino guinea pigs.

PURPOSE: To compare emmetropization in albino and pigmented guinea pigs. METHODS: Distributions of refractive state were examined in 214 albino and 234 pigmented guinea pigs. Albino (A) and pigmented (P) guinea pigs were divided into two groups, hyperopic (H) and myopic (M). Eye development was separately followed in 10 randomly selected animals from each group (AH, AM, PH, PM) from 2 to 10 weeks of age. In addition, deprivation myopia was induced in 36 age-matched albino (18 AH and 18 AM) and 36 pigmented (18 PH and 18 PM) guinea pigs by diffusers that were worn from 2 to 6 weeks of age. Finally, sclera fibril diameters were measured using transmission electron microscopy. RESULTS: Strikingly, the distributions of refractive errors were bimodal at 2 weeks of age, both in albino and pigmented animals, with clearly different averages (-2.86 ± 5.60 diopters [D] vs. 2.13 ± 5.27 D respectively; t = 9.712; P < 0.001). Spontaneous myopia was more common in albino animals: 70.1% were myopic (AM) and 29.9% hyperopic (AH), whereas only 28.6% were myopic (PM) and 71.4% hyperopic (PH) in pigmented guinea pigs. Different from PM and AM did not show any recovery from myopia. With diffusers, AH became more myopic (-7.61 ± 2.71 D and -11.17 ± 2.55 D) than PH (-4.48 ± 1.46 D and -8.28 ± 2.13 D) after 2 and 4 weeks, respectively. Deprivation myopia could still be induced in PM (-1.64 ± 1.44 D and -5.17 ± 1.88 D after 2 and 4 weeks, respectively; P < 0.01) but not in AM. Scleral fibril diameters were smaller in myopic animals, both albino and pigmented. CONCLUSIONS: Deprivation myopia could not be induced in spontaneously myopic but only in hyperopic albino guinea pigs, where it was even higher than in pigmented animals. The distinct effects of albinism on emmetropization will help to elucidate the mechanisms underlying the emmetropization.

[Refractive and biometric changes in adolescent guinea pig eyes in development and recover stages of form-deprivation myopia].

OBJECTIVE: To investigate changes in refraction and vitreous length during form-deprivation and visual re-exposure in guinea pig eyes. METHODS: It was an experimental study. Ninety-six guinea pigs with age of three weeks were randomly divided into form-deprivation and normal control groups (n = 48 in each group). The form-deprivation group was further divided into 4 subgroups (n = 12 in each subgroup) which underwent monocular form-deprivation for 1, 2, 4, and 6 weeks, respectively. At the end of each time point, the form-deprived eyes in all animals were visually re-exposed and followed for 3 (n = 6) and 7 days (n = 6). The control group was also divided into four subgroups (n = 12 in each subgroup) to match the time-points of the form-deprivation group. During form-deprivation and recovery, vitreous length and refraction in each group was measured and compared. RESULTS: There was significant difference in vitreous length (F = 6.108, 28.222, 19.195) and refraction (F = 12.504, 15.003, 6.829) when compared deprived eyes with contralateral eyes 2, 4, or 6 weeks after form-deprivation (P < 0.05). Difference in refraction between deprived eyes and contralateral eyes was -2.36 D, -3.64 D and -3.68 D at 2, 4, 6 week, respectively. Difference in vitreous length was 0.08 mm, 0.19 mm and 0.22 mm. During visual re-exposure, form-deprived eyes changed into hyperopia as compared with contralateral eyes. At day 3 point, there was no significant difference in refraction and vitreous length between form deprived eyes and contralateral eyes in 1 week and 2 weeks groups (F = 0.032, 0.280; P > 0.05). After 7 days recovery, vitreous length and refraction in deprived eyes almost backed to level of contralateral eyes in 1 and 2 weeks groups. At day 3 point, there was significant difference of refraction and vitreous length between form-deprived eyes and contralateral eyes in 4 weeks group and 6 weeks group. After 7 days recovery, there was significant difference in vitreous length for 4 weeks group and there was significant difference in both refraction and vitreous length for 6 weeks group (F = 4.108, 6.317; P < 0.05). CONCLUSION: Form-deprivation causes myopic changes in deprived eyes, during visual re-exposure the refraction recovers and the extent depends on the length of form-deprivation. The recovery rate is faster during the first 3 days and then slower after 3 days. The mechanism of form-deprivation myopia in guinea pig eyes is similar to that of myopia in juvenile human beings.

[Clinical analysis on the effects of laser-assisted subepithelial keratomileusis in treatment of super high myopia].

OBJECTIVE: To assess the clinical efficacy and safety of LASEK in the treatment of super high myopia. METHODS: It was a retrospective case series study. Fifty-six eyes of 33 cases with super high myopia were treated with LASEK. Mean spherical equivalent preoperative was (-11.70 +/- 1.59) D (range from -10.0 D to -15.13 D), mean ablation zone was (5.3 +/- 0.51) mm (range from 4.3 mm to 6.0 mm), mean ablation depth was (146.1 +/- 29.3) microm. The mean time of alcohol used treatment was (29.2 +/- 2.8) seconds. Postoperative follow-up assessments were performed at 1, 3, 6 and 12 months after surgery. Postoperative measurements included slit-lamp microscopy, manifest refraction, un-corrected visual acuity (UCVA), best corrected visual acuity (BCVA), intraocular pressure and haze, etc. The time of follow-up was more than one year. The results were analyzed with ANOVA by SPSS software. RESULTS: Fifty percent of eyes obtained UCVA of > or = 1.0, and 78.6% of eyes obtained UCVA > or = 0.6, at six months after operation. Forty-one percent eyes obtained UCVA of > or = 1.0, and 73.2% eyes obtained UCVA > or = 0.6 at one year postoperatively. The mean UCVA in Snellen chart was 0.85 +/- 0.20, 0.88 +/- 0.28, 0.84 +/- 0.26 and 0.83 +/- 0.28 at 1, 3, 6 and 12 months after operation, respectively. These data were transformed into lgMAR visual acuity and analyzed statistically. There was no significant statistically difference between UCVA at different follow-up periods (F = 0.749, P = 0.518). The postoperative UCVA compared to preoperative BCVA being the same/or improved in 71.4% eyes and decreased in 28.6% eyes at six months after operation; and was 64.3%, and 35.7% at one year after operation, respectively. The effective index was 0.994 and 0.992 at six and twelve months after operation, respectively. The postoperative BCVA compared to preoperative being the same (or improved) and decreased at six and twelve months after operation was 85.3% vs. 14.7%, and 84.8% vs. 15.2%, respectively. The mean BCVA in Snellen chart was 0.90 +/- 0.17, 0.94 +/- 0.24, 0.95 +/- 0.16 and 0.96 +/- 0.16 at 1, 3, 6 and 12 months after operation, respectively. These data were transformed into lgMAR visual acuity and analyzed statistically. There was no significant statistically difference between lgMAR BCVA at difference different follow-up periods (F = 1.567, P = 0.229). The safe index at 6 and 12 months were 1.009 and 1.010. The incidence of refraction regression at 3, 6 and 12 months after operation was 19.6%, 28.6% and 30.3%, respectively. Mean regressive diopter in regressed eyes at 3, 6 and 12 months after operation was (-1.20 +/- 1.08) D, (-1.23 +/- 0.75) D, (-1.49 +/- 1.04) D, respectively. Haze grade 0.5 was 21.4% at 3 months after operation; grade 0.5 and 1 were 8.9% and 5.4% at 6 months after operation, respectively, at 6 months after operation. Haze grade 0.5 was 12.5% at one year after operation. The incidence of high intraocular pressure induced by topical use of corticosteroid eye drop was 8.9%. CONCLUSIONS: LASEK is a safe and effective procedure for correction of super high myopia, though there is still some regression happened after operation and the intraocular pressure should be observed during the follow-up periods.