Factors influencing axial elongation in myopic children using overnight orthokeratology.

Several factors influence axial length in children with myopia treated using overnight orthokeratology. To identify these factors, this retrospective study collected axial length and corneal aberration data on 78 eyes before and 1-year after orthokeratology. Patients were divided according to axial elongation (cut-off, 0.25 mm/year). Baseline characteristics included age, sex, spherical equivalent refraction, pupil diameter, axial length, and orthokeratology lens type. Corneal shape effects were compared through tangential difference maps. Group differences in higher-order aberrations of a 4 mm zone were compared at baseline and 1-year following therapy. Binary logistic regression analysis was conducted to identify the variables determined for axial elongation. Significant differences between both groups included the initial age of wearing orthokeratology lenses, type of orthokeratology lens, size of central flattening area, corneal total surface C12 (1-year), corneal total surface C8 (1-year), corneal total surface spherical aberration (SA) (1-year root mean square [RMS] values), change in total corneal surface C12, and change in front and total corneal surface SA (RMS values). The age when wearing an orthokeratology lens was the most important factor influencing axial length in children with orthokeratology-treated myopia, followed by lens type and change in the C12 of the total corneal surface.

Synergistic effects of defocus-incorporated multiple segments and atropine in slowing the progression of myopia.

Myopia is a leading cause of visual impairment in young people worldwide. It sometimes increases the risk of blindness and reduces life quality. Previous reports have revealed the treatment effects of defocus-incorporated multiple segments (DIMS) and topical atropine (ATP) on myopia control. However, no study has evaluated these two interventions together. In this retrospective study, we aimed to determine whether the combination of DIMS lenses and 0.01% ATP can slow the progression of myopia compared with DIMS lenses or single vision (SV) lenses alone. We included 107 children with myopia who were treated with DIMS and 0.01% ATP combination (DIMS + ATP group), DIMS monotherapy (DIMS group), or a control group (SV group). We compared treatment effects among three groups in axial length and myopia progression. After a 1-year follow-up, the DIMS + ATP group showed a smaller change in axial length and myopia progression than the DIMS and SV groups (P < 0.05). Hence, combination treatment with DIMS and 0.01% ATP might be a better choice for children with myopia.

Analysis of amino acids in human tears by hydrophilic interaction liquid chromatography and quadrupole orbitrap mass spectrometry.

Amino acids in human tears play certain physiological roles and their determination is challenging due to complicated chemical properties. This study described a fast and sensitive method for the simultaneous determination of 15 amino acids (AAs) in tears by hydrophilic interaction liquid chromatography and quadrupole orbitrap mass spectrometry (HILIC-Q-Orbitrap-MS). Amino acids in tears were extracted by methanol, and then cleaned up with a solid phase extraction (SPE) cartridge. Chromatographic separation was performed on a 1.7 µm BEH Amide column within 8 min. Tear samples spiked with free AAs were tested in terms of linearity, sensitivity, repeatability, and recovery. Two stable isotope-labeled amino acids were used as internal standards to improve the method performance. Recoveries for all analytes ranged from 89 to 107%. Intra-day and inter-day precision, expressed as relative standard deviations, were all below 10%, and the method detection limits ranged from 0.02 µmol L-1 to 0.11 µmol L-1. The developed method with high throughput and high analyte specificity shows good promise for consistent analysis of free amino acids in tears.

The use of in-strip digestion for fast proteomic analysis on tear fluid from dry eye patients.

Tear is an accessible fluid for exploring biomarkers of dry eye disease. This study describes a fast proteomic method by LC-Q-orbitrap-MS analysis with in-strip digestion and investigates the tear proteome of dry eye patients. Schirmer's strips were used for collection of tear fluid from patients. These strips were cut into pieces and directly digested with trypsin before mass spectrometry analysis. The data showed that more than 50 proteins were found in tear fluid from dry eye patients. Gene Ontology (GO) annotation showed that most of proteins were transfer/carrier proteins, hydrolyses, enzyme modulators and signaling molecules. Targeted proteomics strategy revealed that 18 proteins were differentially expressed in dry eye patients. Furthermore, it was showed that the common post-translational modification in tear proteins is deamidation of Asn.

[Observation on changes of anterior chamber and chamber angle structures after posterior chamber phakic intraocular lens implantation by ultrasound biomicroscopy].

OBJECTIVE: To study the changes of anterior chamber and chamber angle structures after implantable contact lens (ICL) implantation in high myopia by using ultrasound biomicroscopy (UBM). METHODS: A prospective series case study was conducted on 15 high myopia patients (30 eyes) treated with ICL implant. These patients were followed for one year postoperatively. Intraocular pressure (IOP) was measured by Goldmann applanation tonometer after surgery. All eyes were examined by UBM one year after the surgery. Central anterior chamber depth (ACD), trabecular-iris angle (TIA), the distance between the posterior surface of ICL and the lens and the distance between peripheral surface of ICL and the lens were measured. Nonparametric test was used to compare TIA. One-way ANOVA was used to assess the distance between peripheral surface of ICL and the lens. Repeated Measure ANOVA and Bonferroni test was performed to compare the IOP level before and after surgery. Paired t-test was used to compare ACD. RESULTS: Intraocular pressure changed from (13.75 +/- 2.27) mm Hg (1 mm Hg = 0.133 kPa) preoperatively to (14.27 +/- 1.70), (14.70 +/- 2.07), (14.07 +/- 2.24), (14.00 +/- 2.69) and (13.97 +/- 2.95) mm Hg at 1 week, 1, 3, 6 and 12 months after the surgery, respectively. There was a statistically significant increase of the IOP one month after the surgery, which was normalized completely at 3 months after surgery. The distances between central posterior surface of the cornea to the ICL and the lens were (2.24 +/- 0.21) and (2.97 +/- 0.11) mm, respectively. There was significant difference between these two data (t = 20.63, P < 0.01). TIA was measured in 12:00, 3:00, 6:00 and 9:00. There were no statistically differences between them. TIA was greater than 30 degree in 55.8% of cases. The distance between the central anterior surface of the ICL to the lens (central section) was (0.63 +/- 0.16) mm. No contact was found between the ICL and the crystalline lens. CONCLUSIONS: Posterior chamber phakic intraocular lens implantation for the surgical correction of high myopia is a safe procedure as evaluated with immediate visual and refractive results. We found that the iridocorneal angle and the anterior chamber depth are decreased after the surgery. There is no contact between the crystalline lens and ICL. The ICL contacts with the posterior iris surface.

Comparison of high order aberration after conventional and customized ablation in myopic LASIK in different eyes of the same patient.

PURPOSE: To verify whether there exists any difference in higher order aberrations after undergoing myopic LASIK (laser in situ keratomileusis) with conventional ablation and customized ablation in different eyes of the same patient. METHODS: This was a prospective randomized study of 54 myopic eyes (27 patients) that underwent LASIK using the Nidek EC-5000 excimer laser system (Nidek, Gamagori, Japan). Topography-guided customized aspheric treatment zone (CATz) was used in the first eye of the patient (study group) and the other eye of the same patient was operated on with conventional ablation (control group). Higher order aberrations [root-mean-square (RMS) in the 5-mm zone] of both groups were observed with the Nidek OPD-Scan aberrometer before and 3 months after LASIK. Preoperative mean refractive error was similar between two eyes of the same patient (t=-0.577, P>0.05). RESULTS: Preoperatively, higher order aberrations (RMS in the 5-mm zone) in the CATz ablation and conventional groups were (0.3600+/-0.0341) microm and (0.2680+/-0.1421) microm, respectively. This difference was not statistically significant (t=1.292, P>0.05). Three months after LASIK, higher order aberrations (RMS in 5-mm zone) in the CATz ablation and conventional groups were (0.3627+/-0.1510) microm and (0.3991+/-0.1582) microm, respectively. No statistically significant difference was noted between pre- and postoperative higher order aberrations in the CATz group (t=-0.047, P>0.05). However, a statistically significant increase in higher order aberrations was observed after conventional ablation (t=-5.261, P<0.05). A statistically significant difference was noted in the increase of higher order aberrations after LASIK between groups (t=-2.050, P=0.045). CONCLUSION: LASIK with conventional ablation and topography-guided CATz ablation resulted in the same BSCVA (best spectacle-corrected visual acuity) 3 month after LASIK. Higher order aberrations were increased, but the increase of higher order aberrations after customized ablation treatment was less than that after conventional ablation.

[Posterior chamber phakic intraocular lens for correction of extreme myopia].

OBJECTIVE: To evaluate the efficacy, safety and stability of posterior chamber phakic intraocular lens implantation for the correction of extreme myopia. METHODS: This study included 216 eyes of 113 patients with a mean age of 30 years (18 approximately 49) from January 1997 to December 2005. An implantable contact lens (ICL V2 and V4, Staar Surgical Inc.) was inserted. Patients were examined preoperatively and followed at 1 day, 1 week, 1, 3, 6, 12, 24, and 36 months postoperatively. The examination content included the uncorrected visual acuity, best corrected visual acuity (BCVA), slitlamp examination, refraction, intraocular pressure, endothelial cell morphometry, etc. Spherical equivalent was (17.78 +/- 3.88) diopters before the operation. Surgical implantation was performed through a 3.2 mm clear corneal sutureless incision using paraocular anesthesia. The mean follow-up period was 18.2 months (ranged 6 to 24 months) for refractive data and 24.3 months (ranged 6 to 36 months) for the complications. RESULTS: Successful implantation was achieved in all patients. Postoperatively, all eyes had a significant increase in uncorrected visual acuity. The mean spherical equivalent refraction at the last examination was (-1.00 +/- 1.40), within +/- 1.00 D of the targeted refraction in 191 eyes (88.4%) and within +/- 0.50 D in 165 eyes (76.4%). In eyes in which the preoperative myopia was less than 20.00 D (n = 151), the achieved refraction was within +/- 1.00 D of the intended refraction in 145 eyes (96.0%) and within +/- 0.50 D in 128 eyes (84.8%). The refraction remained stable with a statistically insignificant change (P > 0.05) at each interval during the follow-up. The best corrected visual acuity (BCVA) improved by 1 or more lines in 168 eyes (77.8%) at 1 year after the operation. Four eyes (1.85%) lost 1 line of BCVA. Pupillary block glaucoma requiring surgical intervention occurred in 4 eyes (1.85%). Three eyes (1.39%) developed cataract 1 year after ICL (V2) implantation, all ICLs in these eyes were removed, and the refractive errors were corrected by lensectomy and implantation of low-power posterior chamber IOLs. BCVA was mentioned in all of these eyes. CONCLUSION: Posterior chamber phakic intraocular lens implantation appears to be an effective, safe and reliable method for the correction of extreme myopia.

Bilateral comparison of conventional versus topographic-guided customized ablation for myopic LASIK with the NIDEK EC-5000.

PURPOSE: To compare visual acuity and higher order aberrations before and after myopic LASIK using conventional versus customized ablation. METHODS: This prospective, randomized study included 54 myopic eyes in 27 patients who underwent bilateral LASIK using the NIDEK EC-5000 excimer laser system (NIDEK Technologies, Gamagori, Japan). Customized aspheric treatment zone (CATz) treatment was used in one eye (CATz group) and conventional ablation (conventional group) was used in the fellow eye. Uncorrected visual acuity (UCVA) and higher order aberrations (root-mean-square [RMS] in 4-mm and 6-mm zones) of both groups were observed with the NIDEK OPD-Scan aberrometer before and 3 months after LASIK. Preoperative mean refractive error was similar for both eyes of each patient (P>.05). RESULTS: No statistically significant differences were noted in preoperative higher order aberrations (RMS in 4-mm and 6-mm zones) between groups (P>.05). No statistically significant difference was noted between pre- and postoperative higher order aberrations in the CATz group (P>.05). However, a highly statistically significant increase in higher order aberrations was observed after conventional ablation (P<.001). There was a statistically significant higher increase of higher order aberrations after LASIK in the conventional group than the CATz group (P<.05). Postoperative UCVA with both conventional and customized ablation was not significantly different (P>.05). CONCLUSIONS: LASIK with conventional ablation and CATz ablation resulted in the same UCVA. The increase in higher order aberrations after CATz ablation was less than after conventional ablation.

[Characteristics and correlative factors of posterior corneal surface changes after laser in situ keratomileusis].

OBJECTIVE: To assess the changes of the posterior corneal surface and the factors influencing these changes after laser in situ keratomileusis (LASIK). These factors included the preoperative refraction, preoperative intraocular pressure (IOP), preoperative corneal thickness, spherical equivalent correction and one-week postoperative corneal thickness. METHODS: The posterior corneal radius of curvature for the posterior best fit sphere (PBFS), irregularity of posterior surface, and anterior chamber depth (ACD) were obtained with the scanning slit topography system before and 1 week, 1 month and 3 months after LASIK in 64 eyes of 34 patients with myopic refractive errors of -2.25 to -12.5 diopters. Multiple regression analysis was used to assess the factors that affecting these changes of posterior corneal surface. The difference of radius PBFS and posterior elevation difference (PED) was used as an indicator for the forward shift of posterior corneal surface. RESULTS: The ACD before the surgery and 1 week, 1 month and 3 months after the surgery was (3.2448 +/- 0.2806), (3.2770 +/- 0.2810), (3.2579 +/- 0.2932) and (3.2651 +/- 0.2875) mm, respectively. The PBFS at that time was (6.5095 +/- 0.2177), (6.3731 +/- 0.2127), (6.4257 +/- 0.2358) and (6.4354 +/- 0.2266) mm, respectively. The posterior corneal irregularity at 5 diameters zone was 0.622 +/- 0.142, 0.978 +/- 0.244, 0.884 +/- 0.207 and 0.881 +/- 0.174, respectively The preoperative posterior corneal radius of curvature for PBFS, the irregularity of the posterior surface and the ACD were significantly different from that of postoperative data at each time point (P < 0.01). There was no significant difference in these indexes between 1 month and 3 months postoperatively. Multiple regression analysis showed that factors relevant to the changes of posterior corneal surface were the corrected preoperative refraction (regression coefficient r = 0.0173, P = 0.005) and 1 week postoperative corneal thickness (mm) (regression coefficient r = -1.495, P = 0.001). CONCLUSIONS: The posterior corneal surface after LASIK become steeper and more irregular and remains stable in three months after the surgery. Eyes with thinner corneas and higher myopia requiring more ablation are more predisposed to the changes of posterior corneal surface. The results of the present study should not be used in extremely high degree myopia. A study using a larger group of patients with a longer observation period is required.

Differences between regressive eyes and non-regressive eyes after LASIK for myopia in the time course of corneal changes assessed with the Orbscan.

The aim of this study was to compare regressive eyes with non-regressive eyes after laser in situ keratomileusis (LASIK) for myopia with regard to the time course of biomechanical changes of the cornea and to evaluate the possible roles of these changes in refractive regression following surgery. 15 eyes of 9 patients with refractive regression and 15 eyes of 11 patients with no refractive regression after LASIK for myopia were enrolled in this study. The time courses of central corneal thickness (CCT) and anterior/posterior corneal curvature radiuses (CCR) were measured with Orbscan slit scanning before and 1 week, 1 month and 3 months after LASIK for myopia. The regressive and non-regressive eyes had similar time courses of CCT before and after LASIK, whereas the 2 groups differed in the time courses of corneal shifting movements. In the regression group, the posterior CCR after LASIK was relatively stable (all p > 0.05). By contrast, in the non-regression group, the postoperative posterior CCR at week 1 had a significantly steeper curvature than that at month 3 (p = 0.000). The anterior CCR in the regression group at week 1 had a significantly flatter curvature than that at month 3 (p = 0.002) postoperatively. In contrast, there was no significant change of anterior CCR postoperatively (all p > 0.05) in the non-regression group. Taken together, these data suggest that refractive regression after LASIK might be mainly induced by corneal protrusion rather than central corneal thickening.