Analysis of changes in crystalline lens thickness and its refractive power after laser in situ keratomileusis

AIM: To evaluate changes in the anterior chamber depth (ACD), crystalline lens thickness (LT) and its refractive power after laser in situ keratomileusis (LASIK). METHODS: In all cases, the preoperative and postoperative central ACD which were measured with Pentacam, Orbscan, IOL-Master and A-scan ultrasonography, central corneal true net power which was measured with the Pentacam, Orbscan and IOL-Master, axial length (AL) which was measured with IOL-Master and LT which was measured with the A-scan ultrasonography were compared using the paired sample t test. Ocular refractive errors and lens refractive power at corneal plane were calculated and their correlations were also evaluated before and after LASIK. RESULTS: At 1 week after LASIK, LT and crystalline lens refractive power at corneal plane (Dlens) which were associated with the IOL-Master and Pentacam increased significantly (P <= 0.005), ACD decreased significantly (P <= 0.001), but no significant increase was observed in the Diens which was associated with the Orbscan(P=0.261). Significant correlations between the changes in the ocular refractive errors and Diens which were associated with the Pentacam were observed at 1 week and 6 months after LASIK (P = 0.028; P=0.001). CONCLUSION: LT increased significantly after LASIK, and this might partially lead to ACD decrease, Diens increase and a small quantity of myopic regression.

Objective evaluation of the changes in the crystalline lens during accommodation in young and presbyopic populations using Pentacam HR system

AIM: To quantify the changes in the lens profile with accommodation in different age groups. METHODS: The Pentacam HR system was used to obtain the images of the anterior eye segment from 23 young and 15 presbyopic emmetropic subjects in unaccommodated (with an accommodation stimulus of 0.0D) and accommodated (with an accommodation stimulus of 5.0D for the young group and 1.0D for the presbyopic group) states. The phakic crystalline lens shape, including curvature of crystalline lens and central lens thickness (CLT), and the measurements of anterior segment length (ASL), central anterior chamber depth (CACD) were investigated. The anterior chamber volume (ACV) was also measured. RESULTS: The reduction of CACD and ACV were significant in both groups after accommodation stimulus. From the profile of anterior eye segment, a significant decrease in anterior crystalline lens radii of curvature (-2.52mm) and a mean increase in CLT (0.222mm) and ASL (0.1138mm) were found in the. young group with an accommodation stimulus of 5.0D. However, no statistically significant changes of CLT, ASL, or crystalline lens radii of curvature were found in the presbyopic group. CONCLUSION: Our data showed that the shallowing of anterior chamber during accommodation was caused by the forward bulging of the anterior lens surface, rather than by anterior shifting of lens position in either young or presbyopic subjects.

Preoperative evaluation of human crystalline lens hardness using A-scan ultrasound biometry： a pilot study

Dear Editor,I write to present the results of a study on the correlation between the ultrasound energy consumed during phacoemulsification with various preoperative parameters,including best corrected distance visual acuity（BCDVA）,the signal to noise ratio（SNR）obtained by partial coherence laser interferometry and primarily,lens spikes measurements derived by A-scan ultrasound biometry.Quantification of crystalline lens hardness before cataract removal has been attempted by several researchers in the past.These have been in humans and in animals,in vivo and in vitro,and have used a variety of imaging modalities.

Transient vacuolar changes of the crystalline lens in patients using a dispersive ophthalmic viscosurgical device

AIM:To report the clinical prognosis and pathological findings of accidental lens vacuolar changes in eyes with intraoperative exposure to a dispersive ophthalmic viscosurgical device(OVD).METHODS:Two patients who developed transient lens vacuolar changes during uneventful persistent pupillary membrane(PPM)removal surgery were presented and followed up.This event was speculated to be associated with an intraoperative dispersive OVD DisCoVisc(hyaluronic acid 1.6%-chondroitin sulfate 4.0%)exposure.Then,to provide the pathological basis for our speculation,another four cataract patients were randomly exposed to different OVDs,and their anterior lens capsules were investigated with transmission electron microscopy(TEM).RESULTS:After months,the subcapsular vacuoles in both PPM cases were gradually disappeared without visual deterioration.For the cataract patients,similar lens changes were observed intraoperatively in those exposed to a dispersive DisCoVisc but not a cohesive OVD IVIZ(sodium hyaluronate gel 1.0%).In addition,marked ultrastructural changes,including chromatin condensation,extensive cytoplasmic vacuoles,and obvious intercellular space between lens epithelial cells in the anterior lens capsules of all eyes exposed to DisCoVisc,were observed by TEM.CONCLUSION:The lens vacuolar changes may be associated with a dispersive OVD exposure.Therefore,it is not preferable to use dispersive OVDs in patients with transparent lenses or without the intention of lens extraction.In addition,close follow-ups instead of immediate lens extraction are recommended for the occurrence of similar lens lesions.

23-Gauge Pars Plana Vitrectomy Alone by a Bimanual Technique for the Removal of Dense Posteriorly Dislocated Crystalline Lens

Background: We sought to verify the efficacy and safety of transconjunctival 23-gauge pars plana vitrectomy (PPV) alone by our bimanual technique for the removal of dense posteriorly dislocated crystalline lens. Methods: A retrospective, noncomparative, interventional study of 31 consecutive cases of patients who underwent 23-gauge PPV alone for the removal of dense posteriorly dislocated crystalline lens following complicated cataract surgeries using our bimanual technique was conducted. The main outcomes measured included best-corrected visual acuity (BCVA), preoperative intraocular pressure (IOP), postoperative IOP and postoperative complications. Results: In all 31 cases included in this study, those dense posteriorly dislocated crystalline lenses were successfully removed. The enrolled patients consisted of 17 males and 14 females with a mean age of (75.84 ± 6.17) years (range 59 - 90). The mean follow-up length was (7.61 ± 1.87) months with a range of 6 months to 1 year. The mean preoperative BCVA was 0.22 ± 0.11 logMAR system, and the postoperative BCVA was 0.33 ± 0.07 logMAR system after 6 months of follow-up. The mean operative time was 46.32 ± 4.80 minutes with a range of 38.00 to 57.00 minutes. All of the conjunctival incisions self-closed within the first week with no wound leakage or hemorrhage. The postoperative complications were relatively rare. Conclusions: The removal of dense posteriorly dislocated crystalline lens might be a challenge for micro-incision vitrectomy. Our bimanual technique was proved to be an effective and safe method for those particular dense lenses using 23-gauge alone.

Measurement of crystalline lens tilt in high myopic eyes before cataract surgery using swept-source optical coherence tomography

Background:To measure the crystalline lens tilt in eyes with various degrees of myopia before cataract surgery using swept-source optical coherence tomography(SS-OCT).Methods:We used SS-OCT(IOLMaster 700)to scan 131 emmetropic eyes(axial length<24.5 mm),25 mild/moderate myopic eyes(axial length 24.5–26 mm),and 123 high myopic eyes(52,29,and 42 eyes with axial lengths of 26–28,28–30,and>30 mm,respectively)as part of the routine preoperative examination before cataract surgery.SS-OCT involved B-scans along six meridians.The data were analyzed to assess the magnitude and orientation of the lens tilt and their correlation with other optical biometric parameters.Result:The mean tilt was 3.36±0.98°in emmetropic eyes,3.07±1.04°in mild/medium myopic eyes,and 2.35±1.01°in high myopic eyes.Tilt correlated significantly and inversely with axial length(Pearson’s r=−0.427,P<0.001).The crystalline lens tilt predominantly faced the upper outer quadrant relative to the visual axis,symmetrically in both eyes,with mean angles of 24.32°and 147.36°in the right and left eyes,respectively.The variability in the lens tilt direction increased with increasing axial length(χ^(2) test,P<0.001).Conclusion:The magnitude of crystalline lens tilt decreased with increasing axial length.The direction of tilt was predominantly towards the upper outer quadrant in both eyes.The variability in the tilt orientation increased with increasing axial length.Trial registration:NIH(clinicaltrial.gov),NCT03062085.Registered 23 February 2017.

Measurement of crystalline lens tilt in high myopic eyes before cataract surgery using swept-source optical coherence tomography

Background:To measure the crystalline lens tilt in eyes with various degrees of myopia before cataract surgery using swept-source optical coherence tomography(SS-OCT).Methods:We used SS-OCT(lOLMaster 700)to scan 131 emmetropic eyes(axial length<24.5 mm);25 mild/moderate myopic eyes(axial length 24.5-26 mm),and 123 high myopic eyes(52,29,and 42 eyes with axial lengths of 26-28,28-BO,and>30 mm,respectively)as part of the routine preoperative examination before cataract surgery.SS-OCT involved B-scans along six meridians.The data were analyzed to assess the magnitude and orientation of the lens tilt and their correlation with other optical biometric parameters.Result:The mean tilt was 3.36±0.98。in emmetropic eyes,3.07±1.04° in mild/medium myopic eyes,and 2.35±1.01° in high myopic eyes.Tilt correlated significantly and inversely with axial length(Pearson,sr=-0.427,P<0.001).The crystalline lens tilt predominantly faced the upper outer quadrant relative to the visual axis,symmetrically in both eyes,with mean angles of 24.32°and 147.36°in the right and left eyes,respectively.The variability in the lens tilt direction increased with increasing axial length(x2 test,P<0.001).Conclusion:The magnitude of crystalline lens tilt decreased with increasing axial length.The direction of tilt was predominantly towards the upper outer quadrant in both eyes.The variability in the tilt orientation increased with increasing axial length.Trial registration:NIH(clinicaltrial.gov),NCT03062085.Registered 23 February 2017.

Multiple methods of surgical treatment combined with primary IOL implantation on traumatic lens subluxation/dislocation in patients with secondary glaucoma

AIM:To describe clinical findings and complications from cases of traumatic lens subluxation/dislocation in patients with secondary glaucoma,and discuss the multiple treating methods of operation combined with primary intraocular lens(IOL)implantation.METHODS:Non-comparativeretrospectiveobservational case series.Participants:30 cases(30 eyes)of lens subluxation/dislocation in patients with secondary glaucoma were investigated which accepted the surgical treatment by author in the Ophthalmology of Xi’an No.4Hospital from 2007 to 2011.According to the different situations of lens subluxation/dislocation,various surgical procedures were performed such as crystalline lens phacoemulsification,crystalline lens phacoemulsification combined anterior vitrectomy,intracapsular cataract extraction combined anterior vitrectomy,lensectomy combined anterior vitrectomy though peripheral transparent cornea incision,pars plana lensectomy combined pars plana vitrectomy,and intravitreal cavity crystalline lens phacofragmentation combined pars plana vitrectomy.And whether to implement trabeculectomy depended on the different situations of secondary glaucoma.The posterior chamber intraocular lenses(PC-IOLs)were implanted in the capsular-bag or trassclerally sutured in the sulus decided by whether the capsular were present.Main outcome measures:visual acuity,intraocular pressure,the situation of intraocular lens and complications after the operations.RESULTS:The follow-up time was 11-36mo(21.4±7.13).Postoperative visual acuity of all eyes were improved;28 cases maintained IOP below 21 mm Hg;2cases had slightly IOL subluxation,4 cases had slightlytilted lens optical area;1 case had postoperative choroidal detachment;4 cases had postoperative corneal edema more than 1wk,but eventually recovered transparent;2 cases had mild postoperative vitreous hemorrhage,and absorbed 4wk later.There was no postoperative retinal detachment,IOL dislocation,and endophthalmitis.CONCLUSION:To take early treatment of traumatic lens subluxation/dislocation in patients with secondary glaucoma by individual surgical plan based on the different eye conditions would be safe and effective,which can effectively control the intraocular pressure and restore some vision.

The effect of lens aging and cataract surgery on circadian rhythm

Many organisms have evolved an approximately 24-hour circadian rhythm that allows them to achieve internal physiological homeostasis with external environment.Suprachiasmatic nucleus（SCN） is the central pacemaker of circadian rhythm,and its activity is entrained to the external light-dark cycle.The SCN controls circadian rhythm through regulating the synthesis of melatonin by pineal gland via a multisynaptic pathway.Light,especially shortwavelength blue light,is the most potent environmental time cue in circadian photoentrainment.Recently,the discovery of a novel type of retinal photoreceptors,intrinsically photosensitive retinal ganglion cells,sheds light on the mechanism of circadian photoentrainment and raises concerns about the effect of ocular diseases on circadian system.With age,light transmittance is significantly decreased due to the aging of crystalline lens,thus possibly resulting in progressive loss of circadian photoreception.In the current review,we summarize the circadian physiology,highlight the important role of light in circadian rhythm regulation,discuss about the correlation between age-related cataract and sleep disorders,and compare the effect of blue light-filtering intraocular lenses（lOLs） and ultraviolet only filtering lOLs on circadian rhythm.

Expression and effect of basic fibroblast growth factor on human cataract lens epithelial cells

OBJECTIVE: To detect the expression of basic fibroblast growth factor (bFGF) in human ocular tissues, and to assess the effect of bFGF on the proliferation of human cataract lens epithelial cells (LECs) and its correlation with age. METHODS: Enucleated eyes were subjected to immunostaining for bFGF protein. Human cataract LECs were cultured in vitro, and treated with bFGF for 48 hr. Proliferation was estimated by the positive area ratio of proliferating cell nuclear antigen (PCNA) in immunohistochemistry. RESULTS: bFGF protein was found in various human ocular tissues. bFGF stimulated human cataract LEC proliferation, and there was an age-related decrease in responsiveness of human cataract LECs to bFGF (P

Research progress of lens zonules

Background:The lens zonule,a circumferential system of fibres connecting the ciliary body to the lens,is responsible for centration of the lens.The structural,functional,and positional abnormalities of the zonular apparatus can lead to the abnormality of the intraocular structure,presenting a significant challenge to cataract surgery.Main text:The lens zonule is the elaborate system of extracellular fibers,which not only centers the lens in the eye but also plays an important role in accommodation and lens immunity,maintains the shape of the lens,and corrects spherical aberration.The zonules may directly participate in the formation of cataract via the immune mechanism.Abnormal zonular fibers that affect the position and shape of the lens may play an important role in the pathogenesis of angle closure disease and increase the complexity of the surgery.Capsular tension rings and related endocapsular devices are used to provide sufficient capsular bag stabilization and ensure the safety of cataract surgery procedures.Better preoperative and intraoperative evaluation methods for zonules are needed for clinicians.Conclusions:The microstructure,biomechanical properties,and physiological functions of the lens zonules help us to better understand the pathogenesis of cataract and glaucoma,facilitating the development of safer surgical procedures for cataract.Further studies are needed to carefully analyze the structure–function relationship of the zonular apparatus to explore new treatment strategies for cataract and glaucoma.

Changes in gap junctional intercellular communication in rabbits lens epithelial cells induced by low power density microwave radiation

OBJECTIVE: To demonstrate the changes in gap junctional intercellular communication (GJIC) mediated by low power density microwave radiation in rabbits lens epithelial cells (LECs) and its mechanisms. METHODS: Rabbits' eyes were exposed to 5 mW/cm(2) and 10 mW/cm(2) power densities of microwave radiation for 3 hours. The fluorescence-recovery-after-photobleaching (FRAP) method was used to determine the GJIC. The localization and function of connexin 43 in LECs was detected by laser scanning confocal microscopy. RESULTS: The GJIC of rabbits LECs was inhibited by microwave radiation especially in the 10 mW/cm(2) irradiated samples. A decrease in connexin 43-positive staining was seen in 5 mW/cm(2) x 3 h treated LECs. Intracellular space accumulation and cytoplasmic internalization were clearly demonstrated in 10 mW/cm(2) group. CONCLUSIONS: Low power densities microwave radiation (5 mW/cm(2) and 10 mW/cm(2)) induces damage to connexin 43 and inhibits the GJIC of rabbits LECs. These changes result in an osmotic imbalance within the lens and induce early cataract. 5 mW/cm(2) or 10 mW/cm(2) microwave radiation is cataractogenic.

Expression of nuclear factor- κB in traumatic cataract

Objective ：To study the differences in expression of nuclear factor-κB （NF-κB） between human traumatic cataract and normal lenticular epithelial cells. Methods： Total RNA of anterior capsule specimens was taken under the microscope from normal cadaveric eyes donors and those suffering from traumatic cataract to make semi-quantitative RT-PCR and conduct analysis of differences in expression of NF-κB between them. Results： As compared with the mean of 0.8337 in normal control group, the expression equivalent of NF-κB was 0. 9074 for the lenticular epithelial cells in traumatic cataract sufferers, and the differences are of noticeable significance （ t = 2.447, P 〈 0.05） accordingly. Conclusions： NF-κB is likely a kind of transcription factor necessary to maintain metabolism of normal lenticular epithelial cells. Higher NF-κB available in the traumatic cataract sufferer＇s lenticular epithelial cells means NF-κB is of possible relevance to occurrence and development of traumatic cataract.