Challenges of refractive cataract surgery in the era of myopia epidemic: a mini-review

Myopia is the leading cause of visual impairment in the world. With ever-increasing prevalence in these years, it creates an alarming global epidemic. In addition to the difficulty in seeing distant objects, myopia also increases the risk of cataract and advances its onset, greatly affecting the productivity of myopes of working age. Cataract management in myopic eyes, especially highly myopic eyes is originally more complicated than that in normal eyes, whereas the growing population of cataract with myopia, increasing popularity of corneal and lens based refractive surgery, and rising demand for spectacle independence after cataract surgery all further pose unprecedented challenges to ophthalmologists. Previous history of corneal refractive surgery and existence of implantable collamer lens will both affect the accuracy of biometry including measurement of corneal curvature and axial length before cataract surgery, which may result in larger intraocular lens (IOL) power prediction errors and a compromise in the surgical outcome especially in a refractive cataract surgery. A prudent choice of formula for cataract patients with different characteristics is essential in improving this condition. Besides, the characteristics of myopic eyes might affect the long-term stability of IOL, which is important for the maintenance of visual outcomes especially after the implantation of premium IOLs, thus a proper selection of IOL accordingly is crucial. In this mini-review, we provide an overview of the impact of myopia epidemic on treatment for cataract and to discuss new challenges that surgeons may encounter in the foreseeable future when planning refractive cataract surgery for myopic patients

Tilt, Decentration, and Internal Higher-Order Aberrations of Sutured Posterior-Chamber Intraocular Lenses in Patients with Open Globe Injuries

Purpose. To evaluate the tilt, decentration, and internal higher-order aberrations (HOAs) of sutured posterior-chamber intraocular lenses (IOLs) in patients with open globe injuries. Methods. 46 consecutive patients (47 eyes) who underwent transsclerally sutured IOL implantation were enrolled in this prospective cohort study. Nineteen eyes had a history of open globe injury. The tilt and decentration of the IOLs and the visual quality were measured 1 month after surgery. Results. The horizontal tilt and decentration of the IOLs in the open-globe-injury group were significantly higher than those in the control group (both P<0.05). In the open-globe-injury group, the horizontal decentration was significantly greater in the limbus-sclera-involved group (n=11) than in the only-cornea-involved group (n=8, P=0.040). The internal coma, 3rd-order, and total HOA values at pupil sizes of 4 mm (P=0.006) and 6 mm (P=0.013) were significantly higher in the open-globe-injury group than in the controls. Consequently, the optical quality data for the modulation transfer function and the Strehl ratio (all P<0.05) were significantly poorer in the open-globe-injury group. Conclusions. Open globe injuries damage the structural integrity of the eyeball, resulting in more-misaligned sutured IOLs and poorer visual quality

Evaluation of Anterior Chamber Volume in Cataract Patients with Swept-Source Optical Coherence Tomography

Purpose. To evaluate the anterior chamber volume in cataract patients with Swept-Source Optical Coherence Tomography (SS-OCT) and its influencing factors. Methods. Anterior chamber volume of 92 cataract patients was evaluated with SS-OCT in this cross-sectional study. Univariate analyses and multiple linear regression were used to investigate gender, age, operated eye, posterior vitreous detachment, lens opacity grading, and axial length (AXL) related variables capable of influencing the ACV. Results. The average ACV was 139.80 ± 38.21 mm3 (range 59.41 to 254.09 mm3). The average ACV was significantly larger in male patients than in female patients (P=0.001). ACV was negatively correlated with age and LOCS III cortical (C) grading of the lens (Pearson’s correlation analysis, r=-0.443, P<0.001, and Spearman’s correlation analysis, ρ=-0.450, P<0.001). ACV was also increased with AXL (Pearson’s correlation analysis, r=0.552, P<0.001). Multiple linear regression showed that, with all of the covariates entered into the model, gender (P=0.002), age (P=0.015), LOCS III C grade (P=0.043), and AXL (P=0.001) were still associated with ACV (F=10.252  P<0.001  R2=0.498). Conclusion. With SS-OCT, we found that, in healthy cataract patients, ACV varied significantly among different subjects. Influencing factors that contribute to reduced ACV were female gender, increased age, LOCS III C grade, and shorter AXL

Data from: Clinical efficacy of implantation of toric intraocular lenses with different incision positions: a comparative study of steep-axis incision and non-steep-axis incision

Background: To compare the clinical outcomes after implantation of AcrySof Toric IOLs with different clear corneal incisions. Methods: Sixty cataract patients with regular corneal astigmatism who underwent phacoemulsification combined with implantation of an AcrySof Toric IOL were enrolled. They were divided into two groups according to the position of the clear corneal incision: steep-axis and non-steep-axis. Main outcome measurements included visual acuity, residual astigmatism and changes of corneal astigmatism 3 months postoperatively. Deviation of IOL axis according to the re-calculation using the actual surgically induced astigmatism (SIA) and visual function 3 months after surgery were also evaluated. Results: The corneal astigmatism decreased significantly in steep-axis group 3 months postoperatively (P < 0.05). Besides, more patients in non-steep-axis group were with irregular corneal astigmatism after the surgery (43.33% vs 10%, P = 0.004). The deviation of IOL axis according to the re-calculation using the actual SIA was significantly larger in non-steep-axis group than that of steep-axis group (P < 0.001). Moreover, the postoperative visual function was better in eyes of steep-axis group in various measurements, including point spread function, modulation transfer function and high-order aberrations. Conclusion: Steep-axis clear corneal incision could reduce the cylinder power of toric IOL and lower the chance of postoperative irregular astigmatism, which may consequently improve the postoperative visual quality

Quantitative Phosphoproteomic Comparison of Lens Proteins in Highly Myopic Cataract and Age-Related Cataract

Purpose. To investigate and compare the lens phosphoproteomes in patients with highly myopic cataract (HMC) or age-related cataract (ARC). Methods. In this study, we undertook a comparative phosphoproteome analysis of the lenses from patients with HMC or ARC. Intact lenses from ARC and HMC patients were separated into the cortex and nucleus. After protein digestion, the phosphopeptides were quantitatively analyzed with TiO2 enrichment and liquid chromatography-mass spectrometry. The potential functions of different phosphopeptides were assessed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Results. In total, 522 phosphorylation sites in 164 phosphoproteins were identified. The number of phosphorylation sites was significantly higher in the cortex than in the nucleus, in both ARC and HMC lenses. The differentially phosphorylated peptides in the lens cortex and nucleus in HMC eyes were significantly involved in the glutathione metabolism pathway. The KEGG pathway enrichment analysis indicated that the differences in phosphosignaling mediators between the ARC and HMC lenses were associated with glycolysis and the level of phosphorylated phosphoglycerate kinase 1 was lower in HMC lenses than in ARC lenses. Conclusions. We provide an overview of the differential phosphoproteomes of HMC and ARC lenses that can be used to clarify the molecular mechanisms underlying their different phenotypes

Acute uveal effusion during phacoemulsification with preoperative central serous chorioretinopathy: a case report

Abstract Background We report a case of acute uveal effusion during phacoemulsification in an eye with preoperative chronic central serous chorioretinopathy (CSC). Case presentation A 55-year-old man with a history of chronic CSC for >18 months presented with bilateral opaque lenses. A preoperative ophthalmic examination showed suspected lenticonus and risky anatomical features, including a thick ciliary body, and anterior rotation of the ciliary process and iris root in both eyes. Optical coherence tomography (OCT) detected CSC in the left eye, but the results of fundus photography and B-scan ultrasonography were unremarkable. The anterior chamber flattened during phacoemulsification. Anterior vitrectomy was quickly performed for suspected infusion misdirection syndrome, and was followed by uneventful surgery. On postoperative day 1, fundus photography, type B ultrasound, and OCT revealed uveal exudation in the macula of the left eye. On postoperative day 50, the patient’s visual acuity recovered to 20/32, and fundus photography, ultrasonography, and OCT revealed complete resolution of the uveal effusion. Conclusions This case suggests an association between preoperative CSC and uveal effusion during surgery, because choroidal hyperperfusion and hyperpermeability were present in the patient’s CSC-affected eyes

DNA hypermethylation-mediated downregulation of antioxidant genes contributes to the early onset of cataracts in highly myopic eyes

High myopia is recognized as a risk factor for earlier onset of nuclear cataracts. One possible explanation for this is that lenses in highly myopic eyes are exposed to higher levels of oxygen than normal eyes owing to earlier vitreous liquefaction and, hence, are subjected to oxidative insults. Here, we first compared the methylation levels of six essential antioxidant genes (GSTP1, NRF2, OGG1, TXN, TXNRD1 and TXNRD2) between highly myopic cataract (HMC) and age-related cataract (ARC) lens epithelial samples via Sequenom MassARRAY. We found that specific CpG units in the promoters of GSTP1 and TXNRD2 were hypermethylated and that the expression levels of these two genes were lower in the HMC group than in the ARC group. A luciferase reporter assay confirmed the significance of differentially methylated fragments in the activation of transcription. The importance of GSTP1 and TXNRD2 in antioxidant capacity was confirmed by overexpression or knockdown experiments on cultured lens epithelial cells (LECs). In addition, the expression of DNA methyl transferase 1 (DNMT1) was higher in the lens epithelium of HMC patients than that of ARC patients, and the expression of GSTP1 and TXNRD2 was upregulated by use of a DNMT inhibitor in cultured LECs. Finally, we mimicked the intraocular environment of highly myopic eyes by treating LECs with hydrogen peroxide (H2O2) and observed both alterations in the methylation status of the GSTP1 and TXNRD2 promoters and time-dependent altered expression levels. Therefore, we propose that in an environment with high oxygen, in which lenses in highly myopic eyes are immersed, there exists a vicious cycle composed of increased oxidative stress and decreased enzymatic antioxidants via the hypermethylation of antioxidant genes. Keywords: Cataract, High myopia, DNA methylation, Oxidative stress, GSTP1, TXNRD

Perceived Pain during Cataract Surgery with Topical Anesthesia: A Comparison between First-Eye and Second-Eye Surgery

Purpose. To compare pain scores between first-eye and second-eye cataract surgery and to determine the affecting factors. Methods. 106 first-eye and 53 second-eye cataract surgery patients (mean age: 67 ± 13 and 69 ± 10 years, resp.) were enrolled. The patients completed simplified State-Trait Anxiety Inventory and visual analog scale (VAS) for anxiety questionnaires before surgery, and VAS for pain and Wong-Baker Faces Pain Rating Scale questionnaires after surgery. Blood pressure (BP) and heart rate (HR) were recorded perioperatively. Results. A greater proportion of patients who underwent second-eye surgery reported intraoperative pain compared with first-eye surgery patients (85% versus 35%, P<0.001). The pain scores were higher in second-eye surgery, while the VAS anxiety score was lower in second-eye surgery. Moreover, 31 patients reported greater pain during second-eye surgery than their first one, with higher pain scores than other 22 patients (P=0.032 and 0.003, resp.). The VAS pain score of these 31 patients was positively correlated with the differences between the intraoperative and postoperative diastolic BP, mean arterial pressure, and HR. Conclusions. Cataract patients were likely to have more pain during second-eye surgery, which may be related to lower preoperative anxiety. Monitoring perioperative BP and HR may help to identify patients with intraoperative pain