Haike Guo

Impact of axis misalignment of toric intraocular lenses on refractive outcomes after cataract surgery

PURPOSE: To theoretically and clinically evaluate the impact of axis misalignment of toric intraocular lenses (IOLs) on postoperative refraction. SETTING: International Vision Correction Research Center, University of Heidelberg, Heidelberg, Germany. DESIGN: Case series. METHODS: A method based on mathematical solutions to obliquely crossed spherocylinders was derived according to the pseudophakic refractive properties and used to analyze the impact of toric IOL misalignment on postoperative refraction. The refractive outcomes were theoretically analyzed and actual postoperative outcomes assessed to confirm the theoretically identified impact. RESULTS: The mean IOL misalignment was 12.5 degrees ± 6.7 (SD). Three main factors had an impact on refractive outcomes: hyperopic change in refractive sphere, reduction in astigmatic correction, and rotation of the astigmatic axis. The mean calculated spherical change was 0.32 ± 0.23 diopters (D) and the actual change, 0.36 ± 0.71 D. The mean calculated reduction in astigmatic correction was 0.65 ± 0.45 D and the actual reduction, 0.95 ± 0.54 D, indicating undercorrection of preexisting astigmatism. The mean calculated absolute astigmatic rotation was 32.7 ± 13.2 degrees (range 8 to 55 degrees) and the actual rotation, 29.1 ± 17.4 degrees. There was a correlation between the calculated and actual reduction (r2 = 0.51; P = .001) and between the calculated and actual rotation (r2 = 0.86; P<.001). CONCLUSION: In addition to a reduction in astigmatic correction, misalignment of toric IOLs induced hyperopic spherical change and astigmatic rotation. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Comparison of ray-tracing method and thin-lens formula in intraocular lens power calculations

PURPOSE: To compare the accuracy of the thin‐lens and ray‐tracing methods in intraocular lens (IOL) power calculations in normal eyes and eyes after corneal refractive surgery. SETTING: International Vision Correction Research Centre, University of Heidelberg, Heidelberg, Germany. METHODS: Pseudophakic eye models were constructed using Zemax optical software, importing corneal radii (normal ray tracing) and corneal surface elevation data (individual ray tracing) measured by Pentacam Scheimpflug photography. Algorithms to predict IOL position (effective lens position [ELP]) or postoperative anterior chamber depth [ACDpost]) (Haigis, Hoffer Q, Norrby, Olsen 2) were used in the thin‐lens and ray‐tracing methods. Intraocular lens power was calculated in 25 eyes after corneal refractive surgery using normal and double‐K modified thin‐lens and ray‐tracing methods. RESULTS: Back‐calculation of ELP and ACDpost were well correlated. Using algorithms of Haigis, Hoffer Q, Norrby, and Olsen 2 to predict IOL position, mean absolute prediction errors (MAEs) of the thin‐lens formula were 0.64 diopters (D) ± 0.52 (SD), 0.57 ± 0.46 D, 0.59 ± 0.42 D, and 0.61 ± 0.47 D, respectively; MAEs of normal ray‐tracing method were 0.64 ± 0.50 D, 0.58 ± 0.44 D, 0.59 ± 0.41 D, and 0.62 ± 0.45 D, respectively; MAEs of individual ray‐tracing method were 0.66 ± 0.52 D, 0.59 ± 0.45 D, 0.59 ± 0.43 D, and 0.62 ± 0.50 D, respectively. No statistical differences were found between the thin‐lens and ray‐tracing methods. CONCLUSION: Theoretical thin‐lens formulas were as accurate as the ray‐tracing method in IOL power calculations in normal eyes and eyes after refractive surgery.

Intraocular lens power calculation after laser refractive surgery: Corrective algorithm for corneal power estimation

PURPOSE: To evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after myopic laser refractive surgery using direct corneal measurements. SETTING: International Vision Correction Research Centre, University of Heidelberg, Heidelberg, Germany. METHODS: Corneal parameters in normal eyes and eyes of refractive surgery cases were evaluated by rotating Scheimpflug imaging. Corneal optical power (Koptical) calculated by a Gaussian optics formula was simplified as Koptical = Kanterior + K2 (Kanterior = anterior corneal power; Kposterior = posterior corneal power; K2 = Kposterior − Kanterior × Kposterior × corneal thickness/1.376). The variation and change in K2 induced by refractive surgery were analyzed. A corrective algorithm to calculate Koptical using mean K2 (−6.10 diopters [D]), Kcorrective = 1.114 × measured K − 6.10, was derived based on statistical analysis, which was in accordance with the modified Maloney method. The IOL power after refractive surgery was calculated using Kcorrective. RESULTS: The mean K2 of normal and post‐refractive corneas was −6.10 ± 0.23 D and −6.16 ± 0.17 D, respectively (P = .17). The mean refractive surgery–induced change in K2 was −0.06 ± 0.10 D. The variations in K2 were small (95% confident interval, −6.55 to −5.65 [normal cornea]; −6.48 to −5.70 [pre‐refractive]; − 6.49 to −5.83 [post‐refractive)]. Using Kcorrective for IOL power calculation in post‐refractive cases yielded mean absolute prediction errors of 0.58 ± 0.52 D (Haigis), 0.59 ± 0.49 D (double‐K Hoffer Q), and 0.58 ± 0.47 D (double‐K SRK/T). CONCLUSION: The algorithm that induced low error in corneal power estimation was relatively reliable in IOL calculation after myopic laser refractive surgery. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Corneal power estimation for intraocular lens power calculation after corneal laser refractive surgery in Chinese eyes

PURPOSE: To develop and evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after corneal laser refractive surgery in Chinese eyes. SETTING: Guangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangzhou, China. DESIGN: Prospective comparative case series. METHODS: Corneal parameters in Chinese eyes and German eyes were measured using a rotating Scheimpflug camera. Corneal power was simplified as a corrective algorithm: KC = 1.114 × KM + K2 (KM = measured K reading; K2 = KP − KA × KP × CT/1.376; KA = anterior corneal power; KP = posterior corneal power; CCT = central corneal thickness). The variation and change in K2 induced by refractive surgery were analyzed in Chinese eyes. The corrective algorithm was identified as KC = 1.114 × KM − 6.20. The method was evaluated in Chinese cataract cases after refractive surgery using the Haigis formula. RESULTS: No difference in anterior corneal radius (RA) or CCT between Chinese eyes and German eyes were found; however, the posterior corneal radius (RP), RA/RP ratio, keratometric index, and K2 were different. The mean K2 was −6.23 diopters (D) ± 0.24 (SD) in Chinese eyes and −6.12 ± 0.23 D in German eyes (P<.01). The mean change in K2 induced by refractive surgery was −0.02 ± 0.06 D. The median absolute prediction error in IOL power calculation was 0.43 D (range 0.01 to 1.80 D). CONCLUSION: The algorithm was a relatively reliable method in IOL power calculation after corneal refractive surgery in Chinese eyes. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Pseudophakic eye with obliquely crossed piggyback toric intraocular lenses.

A 72-year-old man presented with high astigmatism (2.25 -5.0 x 45) induced by long-term rotation of a toric intraocular lens (IOL). Corneal astigmatism was 3.78 diopters (D). The corrected distance visual acuity (CDVA) was 20/32. Because of the risk of repositioning, a secondary toric IOL of -3.0/6.0 D especially designed for sulcus implantation was piggybacked through 3.5 mm sutureless clear-corneal incision with a cylindrical axis obliquely crossed with that of the primary IOL. Eight months postoperatively, the corneal astigmatism was 5.04 D. The CDVA was 20/25 with a refraction of 1.0 -2.5 x 70. No interlenticular opacification or significant rotation or decentration of the secondary toric IOL was observed. The refractive properties of this pseudophakic eye were analyzed using a mathematical approach. The calculated postoperative refraction was 0.84 -1.7 x 47. A piggyback toric IOL can be implanted in an obliquely crossed style that allows a secondary toric IOL to correct astigmatism induced by long-term toric IOL rotation.

Biometry and corneal astigmatism in cataract surgery candidates from Southern China

Purpose To analyze biometry data and corneal astigmatism in cataract candidates from Southern China. Setting Guangdong Eye Institute, Guangdong General Hospital, Guangzhou, China. Design Cross‐sectional hospital‐based study. Methods The axial length (AL), anterior chamber depth (ACD), horizontal corneal diameter (white to white [WTW]), and corneal power (keratometry [K], flat K, steep K) were measured using the IOLMaster system. Ocular biometric data were collected and analyzed between 2007 and 2011. Results The study comprised 6750 eyes of 4561 consecutive cataract candidates with a mean age of 70.4 years ± 10.5 (SD). The mean AL, ACD, and WTW were 24.07 ± 2.14 mm, 3.01 ± 0.57 mm, and 11.68 ± 0.45 mm, respectively. All values were statistically significantly greater in men than in women (P < .001) and had a significant trend toward a decrease as age increased (P < .001). The mean K value was 44.13 ± 1.63 D. The median corneal astigmatism was 0.90 D (interquartile range, 0.54‐1.43). Corneal astigmatism of 1.00 D or greater was found in 2963 eyes (43.9%), and 3590 eyes (53.2%) had against‐the‐rule (ATR) astigmatism. The axis of corneal astigmatism turned in the ATR direction with age. Conclusions This study provides reference data for cataract patients from Southern China. The profiles of ocular biometric data and corneal astigmatism can help improve surgical procedures and intraocular lens design for the Chinese population. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

TGF-β2 induces epithelial-mesenchymal transition in cultured human lens epithelial cells through activation of the PI3K/Akt/mTOR signaling pathway

The present study aimed to investigate whether the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway is involved in the transforming growth factor β2 (TGF-β2)-induced epithelial-mesenchymal transition (EMT) in human lens epithelial (HLE) cells. HLEB-3 cells were cultured and stimulated with 10 ng/ml TGF-β2 for 24 h. Western blotting was then performed to analyze the expression levels of connexin 43 and fibronectin, and the activities of Akt and mTOR. Confocal cell immunofluorescence was used to observe the expression of phosphorylated (p)-Akt. The toxicity of 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) was assessed using a Cell Counting Kit-8 assay, and inhibition investigations were performed using a PI3K inhibitor. The expression of connexin 43 was suppressed and the expression of fibronectin was increased when the cells were stimulated with 10 ng/ml TGF-β2 for 24 h. In addition, Akt and mTOR were activated during TGF-β2-induced EMT. Treatment of with LY294002 (20 µM) inhibited the activation of Akt and mTOR and effectively prevented TGF-β2-induced EMT in the HLECs. Therefore, the results of the present study indicated that TGF-β2 induces EMT by activating the PI3K/Akt/mTOR signaling pathway in cultured HLECs.

Intraocular Pressure and Associations in Children. The Gobi Desert Children Eye Study

Purpose To assess the intraocular pressure (IOP) and its association in children in a population living in an oasis in the Gobi Desert. Methods The cross-sectional school-based study included all schools in the Ejina region. The children underwent an ophthalmic examination, non-contact tonometry and measurement of blood pressure and body height and weight. Results Out of eligible 1911 children, 1565 (81.9%) children with a mean age of 11.9±3.5 years (range: 6–21 years) participated. Mean spherical refractive error was −1.58±2.00 diopters. In multivariate analysis, higher IOP (right eye) was associated with younger age (P<0.001; standardized coefficient beta: −0.13; regression coefficient B: −0.13; 95% Confidence interval (CI):−0.18, −0.07), higher diastolic blood pressure (P<0.001;beta:0.13;B:0.05;95%CI:0.03,0.07), higher corneal refractive power (P<0.001;beta:0.11;B:0.23;95%CI:0.12,0.34), more myopic refractive error (P = 0.035;beta: −0.06;B: −0.10;95%CI: −0.19, −0.001), and Han Chinese ethnicity of the father (P = 0.03;beta:0.06;B:0.42;95%CI:0.04,0.89). If age and diastolic blood pressure were dropped, higher IOP was associated with higher estimated cerebrospinal fluid pressure (CSFP) (P<0.001;beta:0.09; B:0.13;95%CI:0.06,0.21) after adjusting for higher corneal refractive power (P<0.001) and Han Chinese ethnicity of the father (P = 0.04). Correspondingly, higher IOP of the left eye was associated with younger age (P<0.001;beta: −0.15;B: −0.16;95%CI: −0.21, −0.10), female gender (P<0.001;beta:0.09;B:0.65;95%CI:0.30,1.01), higher corneal refractive power (P<0.001;beta:0.08;B:0.19;95%CI:0.06,0.32), more myopic refractive error (P = 0.03;beta: −0.06;B: −0.12;95%CI: −0.22, −0.01), and higher estimated CSFP (P<0.001;beta:0.11;B:0.17;95%CI:0.09,0.24). Conclusions In school children, higher IOP was associated with steeper corneal curvature and with younger age and higher blood pressure, or alternatively, with higher estimated CSFP. Corneal curvature radius should be included in the correction of IOP measurements. The potential association between IOP and CSFP as also assumed in adults may warrant further research.

Lack of an association of PD-1 and its ligand genes with Behcet's disease in a Chinese Han population.

Background Behcets disease is a chronic, multi-systemic autoimmune disease. Programmed cell death 1 (PD-1) gene is one of non-human leucocyte antigen genes. It has been demonstrated to be associated with several autoimmune diseases. However, only a few studies have addressed the association of ligand genes of PD-1, PD-L1 and PD-L2 with autoimmune disease. The purpose of this study was to analyze the potential association of the PD-1 and its ligand genes with Behcets disease in a Chinese Han population. Methodology/Principal Findings Four single-nucleotide polymorphism (SNPs) rs2227981 and rs10204525 of PD-1, rs1970000 of PD-L1 and rs7854303 of PD-L2 were genotyped in 405 Behcets patients and 414 age-, sex-, ethnic-matched healthy controls using polymerase chain reaction-restriction fragment length polymorphism assay. The results revealed that there were no significant differences in the genotype and allele frequencies of PD-1 rs2227981 and rs10204525 between the Behcets patients and controls. A similar result was found for PD-L1 rs1970000 versus healthy controls. Only the C allele and the CC genotype of PD-L2 rs7854303 were identified in patients and controls. Stratification analysis based on gender and clinical findings did not show any associations between PD-1 or its ligand polymorphisms and Behcets disease. Conclusions/Significance None of the currently studied SNPs, PD-1 rs2227981 and rs10204525, PD-L1 rs1970000 and PD-L2 rs7854303, are associated with the susceptibility to Behcets disease in a Chinese Han population. More studies are needed to confirm these findings in Behcets patients with other ethnic backgrounds.

Linkage analysis and mutation screening of the rhodopsin gene in a Chinese Bai family with autosomal dominant retinitis pigmentosa

Autosomal dominant retinitis pigmentosa (adRP) is a common form of RP worldwide. Although rhodopsin (RHO) is the most frequently reported adRP gene in many populations, it has not been detected in patients from the Bai nationality, one of the minority ethnic groups of southwest China. In this study, we used linkage analysis and mutation screening to identify the RHO gene in a Chinese Bai family with adRP. We found that in all affected members of the Bai family, the maximum two-point logarithm of odds score obtained was 3.61 and 4.52 at a recombination fraction (θ) of zero, with markers D3S3606 and D3S1292, respectively. Haplotype analysis showed cosegregation at the 1-c region harboring the RHO gene between the two markers with the disease. Direct sequencing of RHO revealed a c.1040C>T (p.Pro347leu) mutation in exon 5, which was supported by the reaction of the restriction enzyme. Two nonpathogenic single-nucleotide polymorphisms, rs7984 and rs2269736, were found in exon 1. To the best of our knowledge, this is the first genetic analysis of a Chinese Bai family with adRP, and a known missense RHO mutation (p.Pro347leu) is responsible for it.