Axial length,vitreoretinal pathology,and anterior chamber depth can predict postoperative refractive outcomes in phacovitrectomy/silicone oil removal

AIM:To evaluate the postoperative refractive prediction error(PE)and determine the factors that af fect the refractive outcomes of combined pars plana vitrectomy(PPV)or silicone oil removal(SOR)with cataract surgery.METHODS:The study is a retrospective,case-series study.Totally 301 eyes of 301 patients undergoing combined PPV/SOR with cataract surgery were enrolled.Eligible individuals were separated into four groups according to their preoperative diagnoses:silicone oil-filled eyes after PPV(group 1),epiretinal membrane(group 2),macular hole(group 3),and primary retinal detachment(RD;group 4).The variables af fecting postoperative refractive outcomes were analyzed,including age,gender,preoperative best-corrected visual acuity(BCVA),axial length(AL),keratometry average,anterior chamber depth(ACD),intraocular tamponade,and vitreoretinal pathology.The outcome measurements include the mean refractive PE and the proportions of eyes with a PE within±0.50 diopter(D)and±1.00 D.RESULTS:For all patients,the mean PE was-0.04±1.17 D,and 50.17%of patients(eyes)had a PE within±0.50 D.There was a significant difference in refractive outcomes among the four groups(P=0.028),with RD(group 4)showing the least favorable refractive outcome.In multivariate regression analysis,only AL,vitreoretinal pathology,and ACD were strongly associated with PE(all P<0.01).Univariate analysis revealed that longer eyes(AL>26 mm)and a deeper ACD were correlated with hyperopic PE,and shorter eyes(AL<26 mm)and a shallower ACD were correlated with myopic PE.CONCLUSION:RD patients have the least favorable refractive outcome.AL,vitreoretinal pathology,and ACD are strongly associated with PE in the combined surgery.These three factors affect refractive outcomes and thus can be used to predict a better postoperative refractive outcome in clinical practice.

Anterior Chamber Depth Changes in Narrow Iridocorneal Angles after Phacoemulsification

Background: The burden of cataract and glaucoma has been increasing. Primary angle closure occurs as a result of crowded anterior segment anatomy causing appositional contact between peripheral iris and trabecular meshwork. Lens extraction has been proposed as a method of deepening anterior chamber and managing intraocular pressure. Purpose: To assess changes in anterior chamber depth after phacoemulsification with intraocular lens implantation in narrow angle eyes. Design: Prospective controlled trial (before-after) study. Method: The study was conducted from March 2015 to August 2017 among the patients of department of Ophthalmology of BSMMU who were diagnosed as cataract with narrow angles. Anterior chamber angle grading of 2 or less (Shaffer grading) in 3 or more quadrants was considered narrow angle (NA). The purposive type sampling technique was applied to collect sample from the study population, as per inclusion and exclusion criteria. Complete clinical evaluation including history, physical examination, relevant ocular examinations and systemic examinations were performed. In this prospective study, subjects underwent phacoemulsification with foldable lens implantation. A scan ultrasonography was performed preoperatively and 10th and 30th postoperative days of surgery. Results: Thirty eyes of 29 patients included in the study, male: female ratio was 1:1, with an overall mean age of 62.03 ± 8.95 years. The mean preoperative central ACD was 2.95 ± 0.35 mm. At 10th and 30th POD mean central ACD were 3.94 ± 0.32, and 3.92 ± 0.28 mm respectively. Mean of increase in central ACD at final follow-up was 0.96 mm (p Conclusion: Phacoemulsification with posterior chamber in bag lens implantation can deepen the anterior chamber depth in patients with narrow angles. Based on these findings, it is concluded that phacoemulsification with foldable intraocular lens implantation is an effective tool in deepening the anterior chamber.

Effect of axial length and anterior chamber depth on the peripheral refraction profile

AIM:To evaluate the effect of axial length(AL)and anterior chamber depth(ACD)on peripheral refractive profile in myopic patients compared to emmetropic participants.METHODS:This cross-sectional study was conducted in right eyes of 58 participants of whom 38 were emmetropic and 20 were myopic.Central and peripheral refraction were measured at 10°,20°,and 30°eccentricities in nasal and temporal fields using an open-field autorefractor.The Lenstar LS900 was used to measure ACD and AL.The participants were divided into three groups of short(<22.5 mm),normal(22.5-24.5 mm),and long eye(>24.5 mm)according to AL and three groups of low ACD(<3.00 mm),normal ACD(3.00-3.60 mm),and high ACD(>3.60 mm)according to ACD.RESULTS:The mean age of the participants was 22.26±3.09 y(range 18-30 y).The peripheral mean spherical refractive error showed a hypermetropic shift in myopic and emmetropic groups although this shift was more pronounced in the myopic group.The results showed significant changes in the spherical equivalent,J0,and J45 astigmatism in all gazes with an increase in eccentricity(P<0.001).The pattern of refractive error changes was more noticeable in long and short eyes versus normal AL eyes.Moreover,the pattern of peripheral refractive changes was much more prominent in the high ACD group versus the normal ACD group and in the normal ACD group versus the low ACD group.CONCLUSION:Peripheral refraction changes are greater in participants with AL values outside the normal range and deeper ACD values compared to participants with normal AL and ACD.

Measurement of the depths at different regions of the anterior chamber in healthy Chinese adults

AIM: To measure the depths of different regions of the anterior chamber(AC) in healthy Chinese adults, and to explore possible correlations with age or gender.METHODS: The AC was imaged by swept-source optical coherence tomography in healthy Chinese adults. The horizontal scan of the right eye was used to measure the anterior chamber depth(ACD) at 199 points.RESULTS: A total of 309 images from 309 subjects were analyzed. The ACD values at nearly all locations were negatively correlated with age(all P<0.05), except for ACD1, 2, 198, and 199(correspond to the iris roots). The mean annual decrease 0.013±0.005 mm/y for all ACDs combined, 0.008±0.004 mm/y for the peripheral region, 0.017±0.003 mm/y for the middle peripheral region, and 0.014±0.001 mm/y for the central region. The mean annual decrease was significantly different among these three regions(P<0.001). The ACD was greater in males than in females(P<0.05). The mean difference in ACD between males and females was 0.081±0.025 mm.CONCLUSION: This study showed that optical coherence tomography can be used to measure the ACD of different regions of the AC. We found reductions in ACD with age, although the reduction varied among different points, in healthy Chinese adults.

Device interchangeability on anterior chamber depth and white-to-white measurements: a thorough literature review

We have reviewed a set of recently published studies that compared the anterior chamber depth（ACD） and/or white-to-white（WTW） distance obtained by means of different measuring devices.Since some of those studies reached contradictory conclusions regarding device interchangeability,this review was carried out in attempting to clarify which clinical devices can or cannot be considered as interchangeable in clinical practice to measure ACD and/or WTW distance,among these devices：A-scan,ultrasound biomicroscopy,Orbscan and Orbscan Ⅱ（Bausch＆Lomb Surgical Inc.,San Dimas,California,USA）,Pentacam and Pentacam HR（Oculus,Wetzlar,Germany）,Galilei（Ziemer,Switzerland）,Visante optical coherence tomography（Visante OCT,Carl Zeiss Meditec Inc.,Dublin,California,USA）,lOLMaster（Carl Zeiss Meditec,Jena,Germany）,and Lenstar LS 900/Biograph（Haag-Streit AG,Koeniz,Switzerland/Alcon Laboratories Inc.,Ft Worth,Texas,USA）.

Distribution of Axial Length, Anterior Chamber Depth and Lens Thickness of Pre-Operative Cataract Patients in Indonesian Population

Purpose: Biometry measurement of pre-operative cataract patients plays a major role in calculating intraocular lens power. This study aimed to review and determine the distribution of biometry components, such as axial length (AL), anterior chamber depth (ACD), and lens thickness (LT) of pre-operative cataract patient in Indonesian population. Methods: A cross-sectional study data were obtained from 2015-2018 cataract surgery at Prima Husada Citra Hospital, Surabaya, East Java, Indonesia. A total of 1295 eyes with cataract was included in the study based on their medical record. We analyzed the data using descriptive analysis and correlated each variable using the Spearman’s Rho analysis. Results: Mean AL, LT and ACD was 23.81 ± 1.46 mm, 4.49 ± 0.55 mm, 3.25 ± 0.70 mm respectively. Male has longer AL and deeper ACD with (p < 0.001), while LT was found thicker in female (p = 0.005). The increase of AL was accompanied by ACD (r = 0.457;p < 0.001) and a thinner LT (r = -0.101;p < 0.001). Conclusions: LT is increased with age while AL and ACD are shortened with age. There was a positive correlation between AL and ACD, but an inverse correlation between AL and LT.

Effect of low dose laser cycloplasty on deepening anterior chamber in chronic angle-closure glaucoma

AIM:To describe the outcome of using low-dose laser cycloplasty(LCP)in chronic angle-closure glaucoma(CACG).METHODS:A retrospective case series.Medical charts of CACG patients who underwent LCP in the Eye Hospital of Wenzhou Medical University were reviewed.The main outcomes included intraocular pressure(IOP),the number of glaucoma medication,anterior segment parameters and surgery-related complications.RESULTS:A total of 7 eyes of 7 CACG patients(age 38.9±11.0y)underwent LCP with a mean follow-up of 27.1±13.7mo(range 16-48mo).Following LCP,mean IOP and glaucoma medications decreased from 26.1±6.1 mm Hg with 3.1±1.1 glaucoma medications pre-treatment to 14.9±3.1 mm Hg(P=0.027)with 0.4±1.1 glaucoma medications(P=0.001)at final follow-up.The anterior chamber depth(ACD),angle opening distance500 and trabecular-iris angle increased from 1.65±0.33 mm,0.05 mm(range 0-0.30 mm)and 5.1°(range,0-31.97°)at baseline to 1.98±0.43 mm(P=0.073),0.53 mm(range 0.42-0.91 mm,P=0.015),45.9°(range,40.2°-59.4°),(P=0.015)in the long-term follow-up,respectively.The deepening of ACD and reopening of anterior chamber angle(ACA)was observed in 6 eyes(85.7%).CONCLUSION:LCP is a promising treatment option for patients with CACG via reducing IOP and glaucoma medication without serious complications.In addition,LCP can bring a significant deepening in ACD and reopening of ACA.

Axial length and anterior chamber indices in elderly population: Tehran Geriatric Eye Study

AIM:To determine the normative distribution of axial length(AL),anterior chamber depth(ACD),anterior chamber volume(ACV),anterior chamber angle(ACA),and some of their associated factors in subjects aged 60 and over.METHODS:In this cross-sectional study,160 clusters were sampled using multi-stage cluster sampling in Tehran,Iran.After a preliminary interview,the participants underwent optometric examinations including visual acuity and refraction measurement followed by slit lamp biomicroscopy.Finally,ocular imaging was done using the Pentacam AXL to measure AL,ACD,ACV,and ACA.RESULTS:A total of 4519 eyes of 2436 participants were evaluated,of whom 58.0%(n=1412)were female.The mean age of the subjects was 67.32±6.05y(range:60-95y).The mean AL,ACD,ACV,and ACA was 23.22 mm(23.18-23.27 mm),2.61 mm(2.59-2.62 mm),126.56 mm3(125.08-128.04 mm3),and 30.61°(30.3°-30.92°),respectively.In the multivariable model,after adjusting for the effect of both eyes,the longest and shortest AL was seen in myopic and hyperopic subjects,respectively.AL,ACD,ACV and ACA were significantly larger in men compared to women(P<0.001).Except ACA,other evaluated parameters showed an inverse correlation with age(P<0.001),however,this correlation was insignificant for AL(P=0.623).CONCLUSION:Normative value of AL,and other biometric parameters are specific for each ethnicity,age and sex group.Any alteration in these parameters and their effect on refraction should be considered in this age group,especially in case of cataract surgery.

The Effects of Anterior Chamber Depth to Endothelial Cell Loss Using Tranversal Phacoemulsification

Background: Phacoemulsification surgery is the most frequent cataract surgery performed in developed countries because of its effectiveness and safety. However, some degree of endothelial loss is inevitable in any type of cataract surgery, including phacoemulsification. Anterior chamber depth (ACD) could be considered as one of important anatomical parameters for preserving endothelial loss from the mechanical and thermal damage that can occur during the procedure. Purpose: To evaluate the effects of ACD on endothelial cell density, hexagonality, coefficient variation (CV) and central corneal thickness (CCT) at one and four weeks after phacoemulsification using transversal ultrasound. Method: This was a prospective study conducted at Cicendo National Eye Hospital Indonesia from April to August 2018, where we performed phacoemulsification in 148 patients with ACD < 3 mm group, ACD ≥ 3 mm group. Specular microscopy examination was performed prior to phacoemulsification and repeated at one and four weeks after surgery. The changes in endothelial density, percentage of hexagonality, CV and CCT between two groups were evaluated and compared. Result: Mean (SD) endothelial density in ACD < 3 mm group and ACD ≥ 3 mm group at 1-week evaluation was 1761.9 (503.3) and 1966.1 (530.6) cells/mm2 respectively, with p value 0.030. At 4-week evaluation, endothelial cell density in ACD < 3 mm group and ACD ≥ 3 mm group was 1537.8 (504.9) and 1798.7 (554.0) cells/mm2 respectively, with p value 0.010. There was no statistical difference regarding hexagonality, CV and CCT between both groups at 1-week and 4-week evaluation. Endothelial density changes percentage also higher in ACD < 3 mm group at 1-week and 4-week evaluation. Conclusion: Endothelial cell density in ACD < 3 mm group was significantly lower compared to ACD ≥ 3 mm group at 1-week and 4-week evaluation after phacoemulsification.

Efficacy of Combined Phacoemulsification and Goniosynechialysis in the Treatment of Patients with Primary Angle Closure Disease and Concomitant Cataract at Preah Ang Duong Hospital in Cambodia

Background: Goniosynechialysis is a surgical procedure that has been shown to slow the progression of glaucoma in oriental eyes with chronic angle closure glaucoma. This procedure was successful in 80% of cases, and the peripheral anterior syenchiae did not exist until one year later. Nonetheless, there is little evidence of its efficacy in our context. Our study aims to investigate the efficacy of goniosynechialysis during phacoemulsification in patients with primary angle closure disease and concomitant cataract. Methods: This was an observational, prospective study. The intra-ocular pressure, need for anti-glaucoma drugs, visual acuity, the extent of synechiae, anterior chamber depth, surgical success rate, and other indicators were monitored for at least three months following surgery. Results: This study included 114 patients (118 eyes), 61 with chronic angle closure glaucoma (51.69%), 33 with primary angle closure (27.97%), and 24 with acute attack angle closure (20.34%), who were surgically treated with phacoemulsification and goniosynechialysis (Phaco-GSL). The mean intra-ocular pressure had significantly decreased three months after surgery (pre- vs post-op: 22.04 ± 10.86 vs 15.41 ± 6.06 mmHg, p-value p-value p-value p-value p-value Conclusion: Regardless of the type of glaucoma, combined phacoemulsification-goniosynechialysis is effective in lowering pressure, restoring vision, reducing the need for anti-glaucoma drugs, and preventing the synechial recurrence. Success was higher in eyes with less extensive synechiae. Phaco-GSL is safe and effective in the treatment of primary angle closure diseases with co-existing cataract.

Comparison of anterior section parameters using anterior segment optical coherence tomography and ultrasound biomicroscopy in myopic patients after ICL implantation

AIM：To compare the agreement of anterior chamber depth（ACD）and central vault measurements obtained by anterior segment optical coherence tomography（AS-OCT）and ultrasound biomicroscopy（UBM）of post surgical high myopic eyes with posterior chamber phakic intraocular lens（Visian ICL;STAAR Surgical）implantation.·METHODS：Fifty-two phakic eyes of 28 high myopic patients who underwent implantable Collamer lens（ICL）surgery for the correction of high myopia were studied.The postoperative ACD,the distance between the corneal endothelium and the anterior surface of ICL（cornea-ICL）and the central vault were measured with the AS-OCT system and the UBM system.Intraclass correlation coefficient（ICC）and the Bland-Altman plot were used to evaluate the repeatability and agreement of two devices.·R ESULTS：The mean ACD,cornea-ICL and central vault in the 52 phakic eyes after ICL surgery was 3.19±0.28 mm,2.47±0.28 mm,0.50±0.19 mm by AS-OCT and3.13±0.25 mm,2.49±0.25 mm,0.44±0.19 mm by UBM,respectively.Pairwise comparison of ACD and central vault measurements showed significant differences between AS-OCT and UBM（〈0.05）.However,no statistically significant difference was found between these imaging techniques in cornea-ICL（〉0.05）.The Pearson correlation coefficient（）between AS-OCT and UBM measurements for ACD,cornea-ICL and vault was0.88,0.80 and 0.89,respectively（〈0.001）.The ICC was0.89-0.94 for the measurements of AS-OCT and UBM.Bland-Altman analysis showed the 95%limits of agreement of ACD,cornea-ICL,central vault measurements between these two devices were-0.20 to 0.32 mm,-0.36to 0.32 mm and-0.12 to 0.24 mm,respectively.58·CONCLUSION：Central ACD and vault measurements using AS-OCT demonstrated a slight significantly higher value than using UBM in phakic eyes after ICL surgery.These two devices should not be used interchangeably for measurements of central ACD and vault in patients after phakic intraocular lens implantation.

Comparison of postoperative anterior segment changes associated with pars plana vitrectomy with and without vitreous base shaving

AIM:To compare changes in anterior segment topography and axial length(AL)evaluated with Pentacam and IOL Master after pars plana vitrectomy(PPV)performed with and without vitreous base shaving.METHODS:This prospective study included patients who underwent PPV or phacoemulsification+PPV(Phaco+PPV)for various indications.Patients who underwent total posterior hyaloid detachment and excessive vitreous base shaving with scleral indentation were referred to as complete PPV(c-PPV).The patients whom posterior hyaloid was separated as far as the posterior arcades and vitreous base shaving with scleral depression was not performed were classified as the partial PPV(p-PPV)group.All patients underwent detailed ophthalmologic examinations preoperatively and lwk,I,and 3mo postoperatively.Changes in the anterior chamber depth(ACD),anterior chamber volume(ACV),iridocorneal angle(ICA)f central corneal thickness(Cd),and keratometric measurements(K1 and K2)were evaluated with Pentacam HR.Changes in the AL measurements were analyzed with IOL Master.RESULTS:A significant increase in ACD was observed in c-PPV cases(P=0.02),but this increase was not significant in the p-PPV group(P=0.053).In contrast,ICA increased significantly in the c-PPV group(P=0.02)but decreased in the p-PPV group(P=0.09).BCVA was significantly improved in the c-PPV group from week 1(P<0.001)while the increase in the p-PPV group reached significance at 3mo(P=0.035).Cd increased in the first week and later returned to baseline in both groups.No significant differences in the other parameters were observed between the groups,and there were no significant changes in intraocular pressure,ACV,AL,K1 or K2 values(P>0.05 for all).CONCLUSION:Incomplete posterior hyaloid excision and not removing the vitreous base in PPV surgeries may create a more stable anterior chamber,thus preventing the downward movement of the lens-iris diaphragm,and may cause ciliary body retraction,thereby reducing ICA.Awareness of these effects can provide some amount of guidance to physicians in selecting the appropriate PPV procedure and preempting surgical complications.

Comparison of anterior segment measurements using rotating Scheimpflug imaging and partial coherence interferometry

AIM:To compare central corneal thickness(CCT) and anterior chamber depth(ACD) measurements using rotating Scheimpflug imaging and partial coherence interferometry.·METHODS:As part of the first phase of Shahroud Eye Cohort Study with 5 190 subjects of 40 to 64 years of age,CCT and ACD were measured using Scheimpflug imaging with the Pentacam(Oculus,Inc.,Lynnwood,WA,USA) and partial coherence interferometry with the Allegro BioGraph(Wavelight,Erlangen,Germany).·RESULTS:After applying exclusion criteria,we had data of 4 387 subjects with a mean age of 50.7±6.2 years.Mean CCT with Pentacam and BioGraph were 528.6 ±33.2μm and 525.6 ±32μm respectively;the difference was statistically significant(P 【0.001),but the correlation was high(R=0.920).Mean ACD measurements using Pentacam and BioGraph were 2.68 ±0.35mm and 2.62 ±0.33mm respectively;the inter-device difference was significant(P 【0.001) with high correlation(R=0.944).The 95% limits of agreements between devices were-22.65μm to28.61μm and-0.16mm to 0.29mm for CCT and ACD measurements,respectively.·CONCLUSION:For both CCT and ACD,the BioGraph gave significantly lower values than the Pentacam(P 【0.05).Despite the high inter-device correlation,the 95%limits of agreements were wide,and this may limit their interchangeability in measuring the CCT and ACD.

Measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients

AIM:To evaluate the measurements of anterior segment parameters using three different non-contact optical devices in keratoconus patients.·METHODS:A hundred and one eyes of 55 keratoconus patients were enrolled in this study.The mean age was26.2 ±8.9 years.The inclusion criteria were keratoconus stage I to III according to the Amsler-Krumeich keratoconus classification.All the measurements were done by the same operator,under the mesopic light condition and repeated with three different optical methods;Visante,Orbscan and Pentacam.The evaluated anterior segment parameters were anterior chamber depth(ACD),central and thinnest corneal thickness(CCT and TCT) and pupil diameter(PD).·RESULTS:The mean CCT measured by Visante,Orbscan and Pentacam were as follows:462.0 ±48.1μm,463.9±60.9μm,476.5±45.3μm,respectively(P =0.873).The mean ACD values were 3.34±0.33mm,3.26±0.33mm,3.49±0.40mm,respectively(P=0.118).The mean PD measurements were 5.11 ±1.14mm,4.80 ±0.85mm,3.80 ±1.38mm,respectively(P 【0.001).The mean TCT measurements of Visante,Orbscan and Pentacam were 437.9 ±48.2μm,447.6±60.6μm and 459.9±44.0μm,respectively(P =0.214).The Visante and Orbscan measured CCT similarly,while Pentacam measured CCT thicker than the other two.The Visante measured TCT thinner than the other two devices.In ACD measurements,Orbscan was the one giving the lowest values.PD was measured differently by the devices.·CONCLUSION:Although TCT,CCT and ACD measurements acquired by Visante,Orbscan and Pentacam in keratoconus patients are similar,PDmeasurements show large differences among the devices.

Analysis of risk and protective factors associated with retinal nerve fiber layer defect in a Chinese adult population

AIM:To investigate the risk and protective factors associated with the retinal nerve fiber layer defect(RNFLD)in a Chinese adult population.METHODS:This study was a cross-sectional populationbased investigation including employees and retirees of a coal mining company in Kailuan City,Hebei Province.All the study participants underwent a comprehensive systemic and ophthalmic examination.RNFLD was diagnosed on fundus photographs.Binary logistic regression was used to investigate the risk and protective factors associated with the RNFLD.RESULTS:The community-based study included 14440 participants.There were 10473 participants in our study,including 7120 males(68.0%)and 3353 females(32.0%).The age range was 45-108y,averaging 59.56±8.66y.Totally 568 participants had RNFLD and the prevalence rate was 5.42%.A higher prevalence of RNFLD was associated with older age[P<0.001,odds ratio(OR):1.032;95%confidence interval(CI):1.018-1.046],longer axial length(P=0.010,OR:1.190;95%CI:1.042-1.359),hypertension(P=0.007,OR:0.639;95%CI:0.460-0.887),and diabetes mellitus(P=0.019,OR:0.684;95%CI:0.499-0.939).The protective factors of RNFLD were visual acuity(P=0.038,OR:0.617;95%CI:0.391-0.975),and central anterior chamber depth(P=0.046,OR:0.595;95%CI:0.358-0.990).CONCLUSION:In our cross-sectional community-based study,with an age range of 45-108y,RNFLD is associated with older age,longer axial length,hypertension,and diabetes mellitus.The protective factors of RNFLD are visual acuity and central anterior chamber depth.These can help to predict and evaluate RNFLD related diseases and identify high-risk populations early.

Comparison of corneal measurements in keratoconic eyes using rotating Scheimpflug camera and scanning-slit topography

AIM: To compare the anterior segment measurements obtained by rotating Scheimpflug camera(Pentacam) and Scanning-slit topography(Orbscan IIz) in keratoconic eyes.METHODS: A total of 121 patients, 71 males(58.7%)and 50 females(41.3%)(214 eyes) with the diagnosis of keratoconus(KC) were enrolled in this study. Following diagnosis of KC by slit-lamp biomicroscopic examination, central corneal thickness(CCT), thinnest corneal thickness(TCT), anterior chamber depth(ACD),and pupil diameter(PD) were measured by a single examiner using successive instrumentation by Pentacam and Orbscan.RESULTS: There was no significant difference between the two instruments for the measurement of CCT and TCT. In contrast, scanning-slit topography measured ACD(3.46±0.40 mm vs 3.38±0.33 mm, P =0.019) and PD(4.97 ±1.26 mm vs 4.08 ±1.19 mm, P 【0.001) significantly larger than rotating Scheimpflug camera.The two devices made similar measurements for CCT(95% CI:-2.94 to5.06, P =0.602). However, the mean difference for TCT was-6.28(95% CI:-10.51 to-2.06, P =0.004) showing a thinner measurement by Orbscan than by Pentacam. In terms of the ACD, the mean difference was 0.08 mm(95%CI: 0.04 to 0.12, P 【0.001) with Orbscan giving a slightly larger value than Pentacam. Similarly, Orbscan measurement for PD was longer than Pentacam(95% CI:0.68 to 1.08, P 【0.001).CONCLUSION: A good agreement was found between Pentacam and Orbscan concerning CCT measurement while comparing scanning-slit topography and rotatingScheimpflug camera there was an underestimation for TCT and overestimation for ACD and PD.

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.

Changes in anterior chamber depth following vitrectomy

Background Anterior segment morphometry is crucial for ophthalmologists to understand the visual outcomes of cataract surgery,keratorefractive surgery,as well as some other anterior segment disorders.Previous reports in literature have shown that anterior chamber depth （ACD） may shift slightly after vitrectomy.This study aimed to characterize the shortterm changes in ACD in eyes after vitrectomy by means of A-scan ultrasound.Methods A prospective case series study was carried out on 29 eyes of 29 patients who underwent vitrectomy as the sole procedure.ACD was measured using A-scan ultrasound biometry shortly before vitrectomy and 1 week,1 month,and 3 months after the surgery.Postoperative ACDs were compared with baseline.Results Twenty-nine patients （16 males and 13 females） were enrolled in the study,with mean age of （50±11） （25-65） years.Twenty-three eyes of 23 patients were vitrectomized for vitreous hemorrhage （VH） and the other six were operated for idiopathic epiretinal membrane （ERM）.The mean preoperative ACD of the VH eyes was （2.98±0.38） mm.No significant difference was found between the ACD of the VH eyes and their fellow eyes （P=0.058）.The average preoperative ACD in the ERM eyes was （2.94±0.31） mm,which was statistically deeper than that of their fellow eyes （（2.85±0.28） mm,P=0.008）.No statistical difference was found in the postoperative average ACD of the VH eyes compared with baseline.In the ERM group,the postoperative ACD in the surgical eyes was still statistically deeper than the fellow eyes 1 week after surgery （P=0.034）.However,such statistical difference disappeared at 1 or 3 months postoperative （P=0.186 and 0.682）.Conclusions ERM may induce deepening of the ACD,which can be recovered by uneventful vitrectomy.VH does not cause shift of ACD,neither does vitrectomy.

Ocular biometry in the adult population in rural central China: a population-based, cross-sectional study

·AIM: To describe the distribution and determinants of ocular biometric parameters and to ascertain the relative importance of these determinants in a large population of adults in rural central China.·METHODS: A population-based, cross-sectional study performed in rural central China included 1721 participants aged 40 or more years. Ocular biometrical parameters including axial length(AL), anterior chamber depth(ACD), radius of corneal curvature(K) and horizontal corneal diameter [white-to-white(WTW)distance] were measured using non-contact partial coherence interferometry [intraocular lens(IOL)-Master].·RESULTS: Ocular biometric data on 1721 participants with a average age of 57.0 ±8.7y were analyzed at last.The general mean AL, ACD, mean corneal curvature radius(MCR), WTW were 22.80±1.12, 2.96±0.36, 7.56±0.26 and 11.75 ±0.40 mm, respectively. The mean values of each parameter in 40 to 49, 50 to 59, 60 to 69, and 70 to91 years age groups were as follows: AL, 22.77 ±0.87,22.76 ±1.06, 22.89 ±1.41, 22.92 ±0.80 mm; ACD, 3.10 ±0.32,2.98 ±0.34, 2.86 ±0.36, 2.77 ±0.35 mm; MCR, 7.58 ±0.25,7.54 ±0.26, 7.55 ±0.26, 7.49 ±0.28 mm; WTW, 11.79 ±0.38,11.75 ±0.40, 11.72 ±0.41, 11.67 ±0.41 mm. The AL, ACD,MCR and WTW were correlated with age and the AL was correlated with height and weight.·CONCLUSION: Our findings can serve as an important normative reference for multiple purposes and may help to improve the quality of rural eye care.

Ultrasonic Evaluation of the Lens Thickness to Axial Length Factor in Primary Closure Angle Glaucoma

Ultrasonic biometry was done in 232 normal eyes and 138 eyes with primary angle closure glaucoma (ACG), using Ultrascan Digital B System IV (10 MHz). The ratio between the lens thickness and the axial length (lens thickness to axial length factor, LAF) was evaluated as a biometric index for assessing the eye with primary ACG in Chinese. LAF of 2.00 was found to be ideal point of demarcation between ACG and normal eyes (i.e., lens thickness equals to 1/5 of axial length). It appears that LAF is helpful i...