Super High Myopia Research Articles

Influence of implantable Collamer lens implantation on choroidal thickness and blood flow density

Objective: To observe the impact of implantable Collamer lens (ICL) implantation surgery on choroidal thickness and blood flow density in myopic patients. Methods: This was a prospective cohort study. Patients undergoing ICL surgery at Qingdao University Affiliated Hospital between June 2021 and May 2023 were consecutively enrolled. Patients were categorized into high myopia (HM) and super high myopia (SHM) groups based on whether their spherical equivalence power exceeded 10.00 D. Comprehensive ophthalmic examinations, including optical coherence tomography, optical coherence tomography angiography, visual acuity assessment, intraocular pressure measurement, and optometry, were performed preoperatively and at 1 week, 1 month, and 3 months postoperatively. Results: A total of 42 patients (84 eyes), with an average age of (25.27±3.18) years, comprising 11 males and 31 females, were enrolled in the study. Among them, 20 patients belonged to the HM group, while 22 patients were in the SHM group. Both choroidal thickness and blood flow density exhibited significant increases at postoperative 1 week and 1 month compared to preoperative levels (P<0.05), but returned to baseline levels by postoperative 3 months. Specifically, the subfoveal choroidal thickness increased from (169.49±61.57) μm preoperatively to (180.16±66.61) μm at 1 week, (186.69±63.32) μm at 1 month, and then reverted to (169.58±60.82) μm at 3 months. The central choroidal blood flow density showed changes from 60.03%±1.60% preoperatively to 61.04%±1.17% at 1 week, 60.42%±1.81% at 1 month, and 60.22%±1.57% at 3 months. Furthermore, the HM group exhibited more pronounced changes in both choroidal thickness and blood flow density across all time points compared to the SHM group. Significant differences were observed in choroidal thickness changes at various areas at 1 month, while changes in blood flow density in specific areas were significant. However, no significant differences were noted at 3 months postoperatively. Correlation analysis revealed a negative correlation of changes in subfoveal choroidal thickness and central choroidal blood flow density postoperatively at 1 week and 3 months with preoperative choroidal blood flow density. Notably, no correlation was found between preoperative choroidal thickness and postoperative changes. Conclusions: In the early period following ICL implantation, the increase in choroidal thickness and blood flow density may be more pronounced in HM compared to SHM, but the two parameters can return to baseline levels by 3 months. ICL implantation transiently affects the fundus microenvironment in myopic patients, with implications of preoperative choroidal blood flow.

Application of Femtosecond Laser + Piggyback Multifocal Intraocular Lens Implantation in Patients with Super-High Myopia Complicated with Cataract

ABSTRACT Objective To observe the clinical effect of piggyback multifocal intraocular lens (IOL) implantation in treating patients with high myopia complicated with cataract. Methods This was a prospective controlled study. We compared 32 eyes of 32 patients who underwent femtosecond laser-assisted cataract surgery with piggyback IOL implantation (two IOLs were implanted into the capsule) with 32 eyes of 32 patients who also underwent the same surgery (one IOL implanted into the capsule) due to high myopia complicated with cataract at the Wuhan Aier Eye Expert Hospital between January 2019 and October 2020. All patients were followed up for three months after surgery. Uncorrected distance visual acuity (UCDVA), uncorrected intermediate visual acuity (UCIVA), uncorrected near visual acuity (UCNVA), best-corrected distance visual acuity, distance-corrected intermediate visual acuity (DCIVA), distance-corrected near visual acuity (DCNVA), postoperative spectacle independence, postoperative visual interference, equivalent spherical lens, defocus curve, and IOL tilt and eccentricity were evaluated. Results Three months after surgery, the patients’ UCIVA, UCNVA, DCIVA, and DCNVA were 0.49 ± 0.07, 0.38 ± 0.15, 0.47 ± 0.09, and 0.36 ± 0.12, respectively, in the research group and 0.56 ± 0.18, 0.72 ± 0.22, 0.55 ± 0.13, and 0.69 ± 0.15, respectively, in the control group; the differences between the two groups were statistically significant (P < .05). The spectacle independence rate was higher in the research group (93%) than in the control group (13%). The overall satisfaction regarding postoperative visual quality was also higher in the research group than in the control group. The absolute mean value of the spherical equivalents was 0.48 ± 0.28 D in the research group and 0.62 ± 0.33 D in the control group; the difference between the two groups was statistically significant (P < .05). Conclusion Piggyback multifocal IOL implantation can expand the multifocal IOL application range, and satisfy the desire of patients with high myopia complicated with cataract to see both near and far.

Five-year outcomes of EVO implantable collamer lens implantation for the correction of high myopia and super high myopia

BackgroundTo evaluate the long-term safety, efficacy, predictability, and stability of implantable collamer lens with a central hole (EVO ICL) implantation for correcting high myopia (HM) and super high myopia (SHM).MethodsThis prospective study evaluated 83 eyes of 46 patients who were divided into groups based on their spherical equivalent refractive error (SE): HM group (− 12 D ≤ SE < − 6 D) and SHM group (SE < − 12 D). They were followed up for 5 years after ICL implantation; assessments of uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractive error, axial length, intraocular pressure, corneal endothelial cell density, and vault were conducted, and a questionnaire was administered.ResuItsAt 5 years postoperatively, the safety indices of the HM and SHM groups were 1.03 ± 0.10 and 1.32 ± 0.39, and the efficacy indices were 0.83 ± 0.25 and 0.86 ± 0.32, respectively. In the HM group, 60.47% and 79.07% of the eyes were within ± 0.50 D and ± 1.00 D of the attempted correction, while it was achieved for 22.50% and 47.50% of the eyes in the SHM group, respectively. The SE of the HM group decreased from − 9.72 ± 1.41 D preoperatively to 0.04 ± 0.39 D 1 month postoperatively and − 0.67 ± 0.57 D 5 years postoperatively, while in the SHM group, it decreased from − 15.78 ± 3.06 D preoperatively to − 0.69 ± 0.97 D 1 month postoperatively and − 1.74 ± 1.19 D 5 years postoperatively.ConclusionEVO ICL implantation is safe, effective, and predictable for correcting HM and SHM. CDVA improved more after surgery for SHM, but the growth of axial length still needs attention.

Visual quality after implantation of a rotational asymmetric refractive intraocular lens in patients with high myopia and cataract

Objective: To evaluate the visual quality after phacoemulsification and implantation of a rotational asymmetric refractive intraocular lens in patients with high myopia and cataract. Methods: A retrospective cohort study. Sixty-two patients (92 eyes) of the First Affiliated Hospital of Zhengzhou University from June 2017 to December 2019 were evaluated after phacoemulsification and implantation of a rotational asymmetric refractive intraocular lens (LS-313 MF30). According to the axial length, the participants were allocated to either a control group or a high myopia group. Among the 33 patients (46 eyes) in the control group, the axial length was shorter than 26 mm; among the 29 patients (46 eyes) in the high myopia group, the axial length was more than 26 mm. The high myopia group was further divided into two subgroups. The super high myopia subgroup included 12 patients (18 eyes), and the axial length was ≥30 mm; the high myopia subgroup consisted of 17 patients (28 eyes), and the axial length was<30 mm and ≥26 mm. Uncorrected distance visual acuity, uncorrected intermediate visual acuity and uncorrected near visual acuity were recorded after surgery. The follow-up time was more than 6 months. At the end of the follow-up, patients' contrast sensitivity (CS), reading acuity, reading speed and visual quality questionnaire results were assessed. The main statistical methods were two-way repeated measures analysis of variance, independent sample t-test, one-way analysis of variance and Kruskal-Wallis test. Results: There were no significant differences in gender distribution, age, or follow-up time between the control and high myopia groups, the control and high myopia subgroup, or the super high myopia subgroup (all P>0.05). At the end of the follow-up, the uncorrected distance, intermediate and near visual acuity of the super high myopia subgroup was 0.07±0.11, 0.34±0.08 and 0.20±0.09, respectively. The difference in postoperative visual acuity was not statistically significant (all P>0.05). The CS and CS with glare of the high myopia group (3 cpd: 1.48±0.18, 1.42±0.16; 6 cpd: 1.75±0.18, 1.76±0.15; 12 cpd: 1.44±0.24, 1.43±0.19; 18 cpd: 0.90±0.23, 0.85±0.20) were significantly different from the control group (3 cpd: 1.66±0.18, 1.62±0.16; 6 cpd: 1.88±0.14, 1.85±0.11; 12 cpd: 1.54±0.18, 1.53±0.14; 18 cpd: 1.06±0.18, 1.01±0.15) (P<0.05), except at 12 cpd (P=0.05). The CS and CS with glare of the super high myopia subgroup (3 cpd: 1.39±0.21, 1.31±0.13; 6 cpd: 1.66±0.16, 1.64±0.12; 12 cpd: 1.32±0.23, 1.31±0.18; 18 cpd: 0.75±0.16, 0.73±0.15) were worst (all P<0.05). A significant difference between the high myopia subgroup and the control group was only found at 3 cpd (1.53±0.13 vs. 1.66±0.18, 1.50±0.13 vs. 1.62±0.16; both P<0.05). The reading acuity and reading speed of the super high myopia subgroup were lower than the high myopia subgroup and the control group, while the differences were not statistically significant (all P>0.05). The questionnaire survey showed that there was no significant difference in the proportion of glare and halo between the two subgroups and the control group (both P>0.05). No patients reported dissatisfaction. The rate of glasses independents was 11/12 in the super high myopia subgroup, 15/17 in the high myopia subgroup and 31/33 in the control group, with no significant difference (P>0.05). Conclusions: The rotational asymmetric refractive intraocular lens is suitable for patients with high myopia and cataract, and has good far and near vision after operation. However, it could result in relatively low CS for super high myopia patients, so rigorous preoperative examination must be done. (Chin J Ophthalmol, 2021, 57: 358-365).

Characterization of the Three Distinct Retinal Capillary Plexuses Using Optical Coherence Tomography Angiography in Myopic Eyes.

PurposeTo segment and quantify three distinct retinal capillary plexuses using optical coherence tomography angiography (OCTA) in myopic eyes.MethodsWe analyzed 96 eyes from 62 subjects with myopia (27.76 ± 7.05 years of age) and evaluated 30 normal eyes from 15 subjects (28.33 ± 3.13 years of age) for controls. En face OCTA images generated by AngioPlex (Carl Zeiss; Oberkochen, Germany) were manually segmented by the progressive matching method into superficial, middle, and deep capillary plexuses (SCPs, MCPs, and DCPs, respectively). Estimated positions for each plexus relative to the reference line were calculated. After strict artifact removal and magnification correction, vessel density (VD) and skeleton density (SD) analyses were performed on each capillary plexus.ResultsMyopic eyes were divided into three groups according to their degree of myopia. We defined the relative estimated positions of the MCP outer boundary to the retinal pigment epithelium fit layer as MCP = –89.317 – 0.178 (central retinal thickness) – 0.580 (ganglion cell inner plexiform thickness); the DCP outer boundary was 38.48 ± 6.24 µm below the inner plexiform layer. VDs were significantly higher in the super-high myopia group than in the control and moderate myopia groups for the DCP (all P < 0.05). SDs in the SCPs were significantly lower in the high myopia and super-high myopia groups than in the control groups (all P < 0.001).ConclusionsWith progressive matching, we segmented three capillary plexuses and defined the relative estimated positions of each capillary plexus to the reference line in myopic eyes. The VD of the DCP increased for more myopic eyes.Translational RelevanceOur study provides a visual method for OCTA image vascular segmentation for myopic eyes.

Optical quality after posterior chamber Phakic implantation of an intraocular Lens with a central hole (V4c implantable Collamer Lens) under different lighting conditions

BackgroundThe current study compared optical quality before and after implantation of a posterior chamber phakic intraocular lens with a central hole [V4c implantable collamer lens (ICL)] under bright and dark lighting conditions by means of the Optical Quality Analysis System™ (OQAS; Visiometrics, Terrassa, Spain).MethodsThis prospective study involved 91 eyes of 46 consecutive high myopia patients (15 males and 31 females, average spherical equivalent − 10.50 ± 0.33D) undergoing implantation of a V4c ICL. The modulation transfer function (MTF) cutoff frequency, Strehl ratio, objective scattering index (OSI), and predicted visual acuities (PVAs; 100, 20, and 9%), under different lighting conditions, were measured before and 1 week, 1 month, and 3 months after surgery.ResultsAll optical parameters showed significant improvements, at all time points, under dark condition after surgery. We observed no significant changes in PVA 9% at 1 week (mean value 0.539, P = 0.12) or 1 month after surgery (mean value 0.573, P = 0.08) under bright condition; but all other postoperative parameters improved significantly. Comparing the two lighting conditions, the OSI decreased more under dark conditions at 1 week (P = 0.02), 1 month (P = 0.004), and 3 months (P = 0.002), but there was no significant difference in any other parameter. In addition, patients were divided into super high myopia (group S, spherical equivalent greater than − 10 D) and high myopia (group H, spherical equivalent from − 6 D to − 10 D), the group S improved significantly more than group H in all parameters, under both bright and dark conditions.ConclusionsV4c ICL implantation improved optical quality under both bright and dark lighting conditions, and had a better ability to reduce the extent of scattering in the dark. Furthermore, group S achieved greater improvement in visual quality, which should be considered by physicians before surgery.

Lenticule Thickness Accuracy and Influence in Predictability and Stability for Different Refractive Errors after SMILE in Chinese Myopic Eyes

ABSTRACTPurpose: To evaluate the differences between the estimated and measured lenticule thickness and relationships in myopic eyes with different refractive errors after small-incision lenticule extraction (SMILE).Methods: This prospective study included a total of 190 eyes (96 patients) with a manifest refraction spherical equivalent (MRSE) of −6.16 ± 1.71 D. The measured lenticule thickness was obtained from digital spectral-domain optical coherence tomography image analysis. The estimated lenticule thickness was obtained from the software program. Comparative statistics and linear regression analyses were performed.Results: At 1 month, the estimated lenticule thickness was 113.68 ± 19.35 µm and the measured lenticule thickness was 96.9 ± 17.5 µm. The difference between the estimated and measured lenticule thickness was 13.63 ± 9.1 µm (p < 0.001) thicker. The difference was lower than the mean data in the moderate myopia group (9.7 ± 6.4 µm) and larger in the high myopia group (12.3 ± 8.8 µm) and the super-high myopia group (17.9 ± 6.9 µm). The discrepancy between the estimated and measured lenticule thickness was significantly dependent on the MRSE (p < 0.001). MRSE only showed significant differences between the three and six-month follow-up visit in the super-high myopic group (p = 0.03).Conclusion: The measured lenticule thickness was thinner than the estimated lenticule thickness for SMILE in most eyes. The higher the refraction, the larger the difference after SMILE surgery. The mismatch between the estimated and measured thickness did not influence the refractive precision and stability of different refractive errors.

Comparison on visual quality of V4 and V4c cposterior chamber intraocular lens implantation for the correction of super high myopia

Objective To compare the visual quality after implantation phakic intraocular lens of ICL V4 and ICL V4c in patients with super high myopia. Methods The data of 84 eyes of 42 patients with super high myopia were selected. All patients were divided randomly into control group and observation group, with 42 eyes of 21 cases in each group.The control group were implanted with ICL V4, the observation group were implanted with ICL V4c. The visual quality of two groups were compared 3 months after treatment. Results The difference in uncorrected visual acuity after surgery was not statistically significant between the two groups (P=0.26). The BCVA after surgery improved ≥2 lines of control group was in 15 cases (71.4%) and the observation group in 16 cases(76.2%), the difference wasn’t statisti-cally significant between the two groups (P=0.32). The postoperative UCVA≥BCVA before surgery was in 19 cases(90.5%)of the control group and 20 cases(95.2%)of the observation group, the difference wasn’t statistically significant between the two groups (P=0.19). The difference of brightlight, dark light, bright light glare and dark glare contrast light sensitivity were not significant between the two groups (P>0.05). The higher order aberrations of the control group were (0.29±0.07)μm, and the observation group were (0.26±0.03)μm, and the difference was not significant between the two groups (P=0.37). Conclusion The difference is not significant in visual quality between ICL V4c and ICL V4 after surgery, but the patients with ICL V4c can avoid peripheral iridectomy. Key words: Myopia, super high; Phakic intraocular lens; ICL V4, ICL V4c; Visual quality

Analysis on the refraction change of high and super high myopia 6 years after LASIK

Objective To observe the diopter and height of cornea posterior surface of high and super high myopia patients after LASIK. Methods The data of 103 eyes of 58 cases with high and super high myopia 6 years after LASIK were collected.Before LASIK all cases of spherical equivalent refraction were - 6.00 D to-18.00 D. There were 40 eyes of 21 cases male and 63 eyes of 37 cases female.The age range was from 20 to 41 years, average was (25.06±7.51) years. The uncorrected visual acuity, best corrected visual acuity, diopter, corneal curvature , axial length and cornea posterior surface height at 1 month and 6 years after surgery were recorded. Results Six years after operation, the uncorrected visual acuity ≥0.8 occupyed for 69.70%.Diopter of myopia under -1.00 D occupyed for 75.75% and under -2.00 D in 90.9%.Corneal posterior surface height was (1.25±3.72) μm. No corneal posterior surface expansion happened .The average axial length was ( 26.84±1.31) mm.The difference was not statistically significant between before and after surgery (P=0.051). The postoperative best corrected visual acuity wasn’t impaired. The safety index was 1.19 and the efficacy index was 0.98. Conclusion After long-term observation, LASIK surgery is effective to high myopia and super high myopia .No corneal posterior surface expansion or secondary keratoconus happened. Key words: Myopia, high, super high; LASIK; Diopter change; Long-term

A randomized controlled clinical study on reverse-chopper prechop technique with phaco-and-chop technique for high myopia associated with hard nucleus cataract

Background The innovation of pre-chop technique lies in shortening surgery duration, reducing ultrasound power, and deseasing the loss of corneal endothelial cells (CECs). Objective This study was to compare the efficacy and safety of pre-chop technique using a reverse-chopper and phaco-and-chop phaco technique to super high myopia associated with hard nucleus cataract. Methods A prospective randomized-controlled-clinical interventional study was performed.Fourty eyes of 40 high myopia associated with cataract patients with Ⅲ-Ⅳ degree of nucleus were enrolled in Beijing Tongren Hospital from March to September 2016.The patients were randomized into the pre-chop group and matched phaco-and-chop group according to random number table, and the self-made reverse chopper-assisted pre-chop phacoemulsification (phaco) surgery and phaco-and-chop phaco surgery were performed on the eyes of different groups, respectively.The phaco power, effective phaco duration and best corrected visual acuity (BCVA) were recorded and compared between the two groups to evaluate the efficacy, and the loss rate of corneal endothelial cells and eyes in different grades of cornea edema after operation were compared between the two groups to assess the safety of surgery procedure.Written informed consent from each patient was obtained prior to relevant examination and surgery. Results The surgery was finished smoothly in the eyes.The mean effective phaco duration was (47.30±11.29) seconds and (57.70±14.51) seconds in the pre-chop group and phaco-and-chop group, respectively, with a significant difference between them (t=-2.530, P=0.016). The BCVA was better at the seventh day after surgery in the pre-chop group than that in the phaco-and-chop group (4.75±0.11 vs.4.67±0.14), showing a significant difference between the two groups (t=2.147, P=0.038). In 1 month after surgery, the CECs loss rate was (10.82±3.77)% in the pre-chop group, which was lower than (16.11±6.47)% in the phaco-and-chop group (t=-3.758, P=0.001). The number of the eyes with grade 2-3 of corneal edema in the pre-chop group was significantly decreased in comparison with the phaco-and-chop group 7 days after surgery (Z=11.822, P=0.008). Conclusions Compared with the conventional phaco-and-chop technique, reverse-chopper prechop technique appears to have a better efficacy and safety in phaco surgery for high-myopia associated with hard nuclear cataractous eyes. Key words: Cataract extraction/methods; Phacoemulsification/methods; High myopia; Lens nucleus, crystalline/surgery; Treatment outcome; Pre-chopping technique; Phaco-and-chop technique; Randomized-controlled clinical study; Reverse-chopper

Clinical study on small incision lenticule extraction surgery for super high myopia

Clinical study on small incision lenticule extraction surgery for super high myopia

Multifocal electroretinogram in non-pathological myopic subjects: correlation with optical coherence tomography

To investigate the changes of retinal function in non-pathological myopic subjects using multifocal electroretinography (mfERG) and to correlate the data with the central macular thickness obtained using optical coherence tomography (OCT). One hundred and thirteen subjects (113 eyes) with age range from 18 to 35y were enrolled in the study. The subjects were divided into four groups according to spherical equivalent (SE) and axial length (AL): emmetropia group (EG, n=31; SE: +0.75 to -0.50 D; AL: 22 to 24 mm), low and medium myopia group (LMMG, n=26; SE: >-0.50 to -6.00 D; AL: >24 to 26 mm), high myopia group (HMG, n=34; SE: >-6.00 to -10.00 D; AL: >26 to 28 mm) and super high myopia group (SHMG, n=22; SE: >-10.00 D; AL:>28 mm). The P1 amplitude density, P1 amplitude, and P1 implicit time of the first-order kernel mfERG responses were obtained and grouped into five rings. The central subfield macular thickness (CST) was obtained using macular cube 512×218 scan of Cirrus HD-OCT. With the increasing of eccentricity, the first positive peak (P1) amplitude density (P=0.0000, 0.0001, 0.0021 in ring 1-3 respectively) and P1 amplitude (all P=0.0000 in ring 1-5) of each group decreased. With the increasing of myopia, P1 implicit time gradually extended (all P=0.0000 in ring 1-3). The average CST in four diagnostic groups was 241.56±12.72 µm, 244.56±12.19 µm, 254.33±11.61 µm, 261.75±11.83 µm respectively. With the increasing of myopia, CST increased (P<0.001). There was negative relationship between CST and P1 amplitude, P1 amplitude density (r=-0.402, P<0.001; r=-0.261, P=0.003). There was positive relationship between CST and P1 implicit time (r=0.34, P<0.001). With the increasing of myopia, P1 amplitude density and P1 amplitude of the first-order reaction gradually reduced. This showed potential decline in retinal function in myopia. To some extent it may reflect the functional disorder or depression of the visual cells. The exact mechanism needs further study.

Long-Term Observation of Triplex Surgery for Cataract after Phakic 6H Implantation for Super High Myopia

Purpose. To analyze the safety, effectiveness, and stability of triplex surgery for phakic 6H anterior chamber phakic intraocular lens explantation and phacoemulsification with in-the-bag IOL implantation for super high myopia in long-term observations. Methods. This retrospective case series evaluated 16 eyes of 10 patients who underwent triplex surgery. Best corrected visual acuity (BCVA), endothelial cell density (ECD), and associated adverse events were evaluated. Results. The mean follow-up time after the triplex surgery was 46 ± 14 months. The mean logMAR BCVA was significantly improved after triplex surgery (P = 0.047). One eye developed endophthalmitis five days postoperatively and underwent pars plana vitrectomy (PPV). Five eyes with preoperative severe endothelial cell loss developed corneal decompensation and underwent keratoplasty at a mean time of 9.4 ± 2.6 months after the triplex surgery. One eye had graft failure and underwent a second keratoplasty. The eye developed rhegmatogenous retinal detachment and underwent PPV with silicone oil 18 months later. ECD before the triplex surgery was not significantly different compared with that at last follow-up (P = 0.495) apart from these five eyes. Three eyes (18.8%) developed posterior capsule opacification. Conclusions. Triplex surgery was safe and effective for phakic 6H related complicated cataracts. Early extraction before severe ECD loss is recommended.

Objective optical quality and intraocular scattering in myopic adults.

To evaluate objective optical quality and intraocular scattering in adults with myopia. This was a cross-sectional study. Patients between 18 and 40 years of age were recruited from those undergoing routine preoperative examinations prior to myopic refractive surgery. The spherical equivalent refraction (SE) ranged from -14.25 to -0.63 diopters (D). Right eyes of 274 subjects were included for factor analyses: 25 eyes were super-high myopia (SE < -9 D), 88 eyes were high myopia (-6 D > SE ≥ -9 D),133 eyes were moderate myopia (-3 D > SE ≥ -6 D), and 28 eyes were low myopia (SE ≥ -3 D). A double-pass system was used to measure the modulation transfer function cutoff frequency (MTFcutoff) and objective scatter index (OSI). Mean MTFcutoff was 32.38 ± 9.73 and 27.61 ± 8.11 cycles per degree (cyc/deg) in the high and super-high myopia groups, significantly lower than 39.92 ± 10.53 and 37.39 ± 8.74 cyc/deg in the low and moderate groups (P < 0.01). Mean OSI was 0.89 ± 0.61 and 1.33 ± 0.65 in the high and super-high myopia groups, significantly higher than in the low and moderate groups, 0.50 ± 0.39 and 0.57 ± 0.44 (P < 0.01). No significant difference was found between the low myopia and the moderate myopia group in any of the parameters (P > 0.05). Other factors such as eye side, sex, and age did not significantly affect optical quality parameters or OSI in this study population (P > 0.05). Optical quality and intraocular scattering varied among individuals with myopia. High myopia has more influence on retinal image quality and scattering than moderate and low myopia. Our study also helps to establish MTFcutoff and OSI standards for Chinese refractive surgery candidates.

Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT.

To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography (OCT). Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length: low and medium myopia group (LMMG), high myopia group (HMG) and super high myopia group (SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness, central subfield thickness, inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis. There was no significant difference in age among the three groups (P=0.2789). The mean refraction error in the LMMG, HMG, and SHMG groups was -2.49±1.38D, -8.53±1.95D and -13.88±1.76D, respectively (P<0.001). The central subfield thickness of three groups was 244.56±12.19µm, 254.33±11.61µm and 261.75±11.83µm, respectively, and there were statistically significance between random two groups. The total average macular thickness, inner/outer macular thickness, and macular volume decreased with increased myopia/axial length. Average foveal thickness had negative correlations with refractive error (P<0.001), and positive correlations with axial length. The inferior and temporal inner macular thickness, all the quadrants of outer ring, total average macular thickness and macular volume featured positive correlations with refractive error, and negative correlations with axial length. Average foveal thickness, superior and temporal inner macular thicknesses, and temporal outer macular thickness was lower in females compared to males. With an increase in myopia degree/axial length, the average foveal thickness increased and the inner/outer macular thickness decreased. Females featured thicker average foveal thickness, and thinner macular thickness compared to males.

The efficacy of phacoemulsification and aspiration combined with Bigbag IOL implantation for superhigh myopia with cataract

Objective To study the clinical effects of phacoemulsification and aspiration combined with Bigbag intraocular lens implantation for superhigh myopia with cataract.Methods Twenty-five cases (30 eyes) of superhigh myopia with cataract were treated by phacoemulsification combined with Bigbag intraocular lens implantation under surface anesthesia.Flexibility of vitreous body,best corrected visual acuity ( BCVA),refraction diopter and complications were observed after surgery.The follow-up period was 1 to 8 months.Results For the BCVA,8 eyes were ≥0.5(26.7％ ),16 eyes were 0.3 ～0.4(53.3％ ),and 6 eyes were ＜ 0.3 (20.0％),respectively.No posterior capsular rupture was detected during the surgery.Corneal edema of various degrees showed on day 1 after surgery,and eliminated 3 to 10 days later.No retinal detachment,choroids detachment,cystoid macular edema and after-cataract were noted.Conclusion Phacoemulsification combined with Bigbag intrancular lens implantation could improve the visual acuity of patients with superhigh myopia with cataract,enhance the stability of vitreous body and prevent the occurrence of complications. Key words: Cataract; Phacoemulsification; Bigbag intraocular lens

Corneal Asphericity and Its Related Factors in 1052 Chinese Subjects

To observe and analyze corneal asphericity and its related factors in Chinese subjects. The corneal asphericity of 1052 right eyes from a Chinese population was determined using the Wavelight-ALLEGRO Topographer. The corneal asphericity coefficient Q describes the rate of curvature variation of the cornea from its center to the periphery and specifies the type of conicoid that best represents its shape. All cases were grouped by age in years (A: ≤ 9; B: 10 to 19; C: 20 to 29; D: 30 to 39; E: 40 to 49; F: ≥50), and 223 myopic cases were grouped by magnitude in spherical equivalent (SE) refractive error (low myopia, > -3.0 diopters (D); moderate myopia, -6.0 D < SE ≤ -3.0 D; high myopia, -8.0 D < SE ≤ -6.0 D; and super high myopia, SE ≤ -8.0 D). In addition, corneal asphericity was analyzed by corneal quadrant (nasal, temporal, superior, and inferior) and two meridians (vertical and horizontal). The mean Q value of 1052 right eyes was -0.30 ± 0.12. Although statistical differences were found between some age groups, no statistical correlation between Q values and age was found in this study (r = -0.58, p = 0.06). Q values of the nasal and superior corneal quadrant were significantly more oblate than that of the temporal and inferior quadrants, respectively (both p < 0.0001). A trend toward more oblate Q values was found as the level of myopia increased (r = 0.166, p = 0.013). There was a negative relationship between Q value and central corneal radius in this entire study population (r = -0.09, p = 0.004). Corneal asphericity in this population is related more to corneal quadrant location than to age. The results from this study suggest that degree of myopia and central corneal radius both have a significant though weak association with corneal asphericity in Chinese eyes.

The change of contrast sensitivity of myopic patients after laser in situ keratomileusis

Objective To evaluate the contrast sensitivity function before and after laser in situ keratomileusis(LASIK).Methods With test chart,contrast sensitivity was measured in randomly selected 58 subjects(112 eyes)before,1 month and 3 months after LASIK.The contrast sensitivity was measured at 1.5,3.0,6.0,12.0 and 18.0 cycles per degree(c/d)spatial frequency respectively and comparison was made.Results The patients achieved the mean uncorrected visual acuity(UCVA) of 1.07 ±0.15 and 1.10±0.20 at postoperative 1-month and 3-months respectively.Which were close to the correct preoperative visual acuity.There was a general reduction in contrast sensitivity in all spatial frequencies at postoperative 1-month when they were compared with the preoperative contrast sensitivity.The difference at 6.0,12.0 and 18.0 c/d spatial frequency was statistically significant(P<0.01).By the 3-month visit,all eyes showed a recovery of contrast sensitivity function.Near contrast sensitivity in 6.0.12.0 and 18.0 c/d spatial frequency had a decline in superhigh myopia patients at 3-month(P<0.01).Conclusion Near contrast sensitivity became worse at the early stage after LASIK.It could be recovered later on.But that in super high myopia would take a longer recover time. Key words: laser in situ keratomileusis; myopia; contrast sensitivity