Average Anterior Chamber Depth Research Articles

Agreement of implantable collamer lens sizes using parameters from different devices

ObjectiveTo assess agreement and repeatability of white-to-white (WTW) and anterior chamber depth (ACD), and agreement of implantable collamer lens (ICL) size using these measurements from different devices.Methods and analysisA retrospective...

How direct measurements of worker eyes with a Scheimpflug camera can affect lensdose coefficients in interventional radiology

The 2013/59/Euratom Directive reduced the occupational exposure limits for the lens. Since it has become crucial to estimate the dose absorbed by the lens, we have studied the individual variability of exposed workers’ ocular conformations with respect to the data estimated from their personal dosimetry. The anterior eye conformations of 45 exposed workers were acquired using Scheimpflug imaging and classified according to their sight conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario using Monte Carlo code. The models were dosimetrically analysed by simulating setup A, a theoretical monoenergetic and isotropic photon source (10–150 keV) and setup B, a more realistic interventional setting with an angiographic x-ray unit (50, 75, 100 kV peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1–10.1) mm. Using these data for model reconstruction, dose coefficients (DCs) were simulated for all ocular structures. Regardless of the eye model used, the DCs showed a similar trend with radiation energy, which highlighted that for the same energy and setup, no significant dependence on ocular morphology and workers’ visual conditions was observed. The maximum difference obtained did not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction, compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the dose absorbed by the other eye structures, it is, instead, essential to know the spectrum of the source that has generated the irradiation, since there are differences between monoenergetic sources and more realistic angiographic units.

Evaluation of the Diagnostic Performance of Swept-Source Anterior Segment Optical Coherence Tomography in Primary Angle Closure Disease

To evaluate the diagnostic performance of swept-source anterior segment optical coherence tomography (SS-OCT) in differentiating eyes with primary angle closure disease (PACD) from eyes of control subjects, as well as eyes with PAC and PAC glaucoma (PACG) from eyes with PAC suspect (PACS) disease. Multicenter cross-sectional study. Chinese patients were classified into control, PACS, and PAC/PACG groups. The area under the receiving operating characteristic curve (AUC) from logistic regression models was used to evaluate discriminating ability. Sensitivity and specificity were calculated, and performance of the models was validated using an independent dataset. A total of 2928 SS-OCT images from 366 eyes of 260 patients were recruited to develop diagnostic models. The validation dataset included 1176 SS-OCT images from 147 eyes of 143 patients. For distinguishing PACD from control eyes, average anterior chamber depth had the highest AUC (0.94). With a cutoff of 2.2 mm for average anterior chamber depth, the sensitivity and specificity were 90.2% and 85.2% in the training set. For distinguishing PAC/PACG from PACS, a multivariate model had an AUC of 0.83, with sensitivity and specificity of 82.0% and 62.8% in the training set. The validation set confirmed the findings. SS-OCT of the anterior segment showed excellent diagnostic performance distinguishing PACD from normal eyes and moderate diagnostic ability distinguishing eyes with PAC/PACG from eyes with PACS. ACD alone may provide a simple and effective way to diagnose PACD from control subjects. As ACD can be obtained using other more available modalities, this has implications for the early diagnosis of PACD.

Evaluating the anterior chamber depth and axis length in high myopia

Objectives: to evaluate the anterior chamber depth (ACD), axis length (AL), and the relationships between ACD and AL in high myopia patients. Objects and methods: a descriptive study was conducted on 168 eyes (88 patients, ≥12 years old) diagnosed with high myopia (more than -6D). Results: the average myopia degree, ACD, and AL were -8.75±2.61D, 3.72±0.20 mm, and 27.33±1.49 mm, respectively. There was no statistical signification between ACD and myopia degree (r=0.044; p>0.05), strong correlation between AL and myopia degree (r=-0.762; p<0.001), and weak correlation between ACD and AL (r=0.165; p<0.05). Conclusion: myopia degree does not relate to ACD, but has a strong correlation to AL. Measuring the AL on high myopia patients is important for the diagnosis, prognosis, and treatment.

Clear lens extraction for patients who are unfit for laser-assisted in situ keratomileusis and implantable contact lenses in central Indian population.

Purpose:The purpose of this study is to establish the safety of clear lens extraction (CLE) for the correction of high myopia in patients unfit for implantable contact lenses (ICLs) and laser in situ keratomileusis in the central Indian population.Methods:In this retrospective observational study performed at a tertiary care centre, medical records of the patients who had undergone CLE with implantation of intraocular lens (IOL) to treat high myopia were retrieved. Details of the demographic profile, surgical procedure, complications, power, and type of IOLs implanted were recorded.Results:The average postoperative follow-up period was 64.1 ± 4.2 months. The average postoperative spherical power was −1.4 ± 0.6 D, which was much lower than the preoperative spectacle power - 15 ± 4.4 D. There was improvement in the postoperative visual acuity (0.4 ± 0.2 logMAR) from the preoperative distant uncorrected visual acuity (0.8 ± 0.2 logMAR). No significant change in intraocular pressure (IOP) was observed. The postoperative average anterior chamber depth (ACD) (2.66 ± 0.1 mm) was significantly deeper than the preoperative ACD (2.61 ± 0.1 mm) P = 0.00. Barrage laser was required for lattice degeneration in one patient before CLE and in two patients during follow-up. Two patients (8.7%) required Nd:YAG capsulotomy for posterior capsular opacification. None of the patients had corneal decompensation, retinal detachment, or endophthalmitis.Conclusion:CLE with implantation of IOL is the safe procedure for correcting high myopia in patients who are unfit for ICL. None of the patient had eye loss in the follow-up period of 5 years. The low incidence of complications can be attributable to the closed chamber lens removal and implantation of IOL and prophylactic retinal treatment.

Anterior chamber dimensions, angles and pupil diameter in patients with Down syndrome: A comparative population-based study.

Purpose:To study the anterior chamber (AC) dimensions, angles and pupil diameter (PD) in patients with Down syndrome compared to normal controls.Methods:Prospective study is comparing the AC parameters in patients with Down syndrome aged 10-30 years and age-matched controls. Extracted indices included average anterior chamber depth on the 2-mm ring (ACD-2 mm), 4-mm ring (ACD-4 mm), at the corneal apex from the endothelium (endo-ACD), at the corneal apex from the epithelium (epi-ACD), anterior chamber volume (ACV), mean anterior chamber angle (ACA), and PD measured by Pentacam.Results:Data from 202 patients with Down syndrome (age 17.2 ± 4.8 years) were compared with 190 normal controls (age 17.2 ± 4.5 years). In Down and normal groups, mean ± SD were 2.51 ± 0.31 and 2.83 ± 0.34 mm for ACD-2 mm, 1.65 ± 0.30 and 1.93 ± 0.31 mm for ACD-4 mm, and 3.03 ± 0.29 and 3.24 ± 0.26 mm for endo-ACD, 3.54 ± 0.29 and 3.80 ± 0.26 mm for epi-ACD, mean 169.31 ± 30.38 and 200.17 ± 33.20 mm3 for ACV, 40.69 ± 4.50 and 39.97 ± 4.12° for ACA, and 2.79 ± 0.62 and 3.59 ± 0.80 mm for PD, respectively (all P < 0.001). None of the studied indices significantly correlated with age, except for ACA (P = 0.011). All parameters, except for PD, were significantly higher in males compared to females (all P < 0.001). Temporal ACA was significantly wider in male subjects (44.61 ± 6.52 vs. 42.24 ± 6.52°; P < 0.001).Conclusion:The AC in patients with Down syndrome is smaller than normal individuals. AC in females with Down syndrome is smaller than males, and the narrower ACA is attributable to the difference in the temporal angle and not the ACA in other meridians.

Evaluation of Anterior Chamber Depth and Anterior Chamber Angle Changing After Phacoemulsification in the Primary Angle Close Suspect Eyes.

BACKGROUND:Phacoemulsification surgery has the ability to deeply alter the segment anterior morphology, especially in eye with shallow anterior chamber (AC), narrow anterior chamber angle (ACA). However, the changes of anterior chamber depth (ACD) and ACA on the close angle suspect eyes after phacoemulsification have not been mentioned in many studies. So, we conduct this research.AIM:To evaluate the alteration in the ACA and ACD after phacoemulsification in the close angle suspect eyes.METHODS:Interventional study with no control group. Subjects were the primary angle closure suspect (PACS) eyes, that were operated by phacoemulsification with intraocular lens (IOL) at Glaucoma Department of VNIO from December 2017 to October 2018.RESULTS:29 PACS eyes with cataract were operated by phacoemulsification with intraocular lens. After 3 months of monitoring, the average ACD augmented from 2.082 ± 0.244 to 3.673 ± 0.222 mm. AOD500 increase from 0.183 ± 0.088 to 0.388 ± 0.132 μm, AOD750 increased from 0.278 ± 0.105 to 0.576 ± 0.149 μm. The TISA500 enlarged from 0.068 ± 0.033 to 0.140 ± 0.052 mm2, TISA750 enlarged from 0.125 ± 0.052 to 0.256 ± 0.089 mm2 at the third month (p < 0.01).CONCLUSION:Phacoemulsification surgery increases the ACD and enlarged the angle in the PACS eyes.

Flat Anterior Chamber after Trabeculectomy in Secondary Angle-Closure Glaucoma with BEST1 Gene Mutation: Case Series.

PurposeTrabeculectomy has been regarded as a mainstay of initial treatment in eyes of angle closure glaucoma (ACG) with peripheral anterior synechia > 180° in the Chinese population while its efficacy in secondary ACG with BEST1 gene mutation remains unclear. We set out to investigate the treatment outcome of trabeculectomy for secondary ACG in a group of patients with autosomal recessive bestrophinopathy (ARB).MethodsIn this retrospective case series study, 8 secondary ACG patients with ARB and their 4 recruited family members underwent a thorough ophthalmic examination including best-corrected visual acuity, Goldmann applanation tonometry, gonioscopy, and fundus examinations. Ultrasound biomicroscopy, optical coherence tomography (OCT), ultrasound A-scan, B-scan, electro-oculography (EOG), Humphrey perimetry, fundus photography, fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) were also performed. Blood samples were obtained in the patients and their available family members to analyze the variants of the BEST1 gene. Trabeculectomy was performed in the 8 patients (15 eyes).ResultsThe age of onset varied from 13 to 38 years. The average axial length (AL) of the affected eyes was 21.82 ± 0.92 mm and the average anterior chamber depth (ACD) was 2.19 ± 0.29 mm. There was marked axial shallowing of the anterior chamber in all 15 eyes after trabeculectomy, and was not improved with potent mydriatics. The IOP was elevated in 3 eyes. Variable degree of yellowish subretinal deposits was observed in the posterior retina. The FFA showed punctuate or patched hyperfluorescence suggesting retinal pigment epithelium impairment. The ICGA demonstrated dilatation of choroidal vessels. The OCT revealed diffused neuroretinal detachment in the posterior and midperipheral retina, with intraretinal fluid collections, and hyperreflective subretinal accumulations. The average subfoveal choroidal thickness of the patients was 382.36 ± 80.09 μm. All the patients and enrolled family members carried mutation in BEST1 gene.ConclusionsARB is a rare condition with fundus manifestations mimicking various diseases. Careful discrimination should be taken to exclude any secondary causes for ACG before treatment. Concerning the high incidence of postoperative shallow anterior chamber, selection of filtering surgery should be very careful in these patients.

The Stabilization Time of Ocular Measurements after Cataract Surgery

ABSTRACTPurpose: To determine the stabilization time of automated refraction, ocular biometric parameters, keratometry, and central corneal thickness (CCT) and to find the optimal time for glasses’ prescription after cataract surgery. Methods: This was a prospective, case series study of 62 consecutive eyes with senile cataracts. Patients undergoing uncomplicated phacoemulsification surgery were included in the study. Automated refraction, keratometry, ocular biometric parameters, and CCT were recorded at baseline before cataract surgery and at follow-up visits at one day, one week, two weeks, and four weeks after surgery. Results: The study was composed of 62 eyes of 62 patients with a mean age of 66±12.38 (range, 40 to 84 years). The automated refraction stabilized one week after surgery and changed minimally between the first week and the first month after cataract surgery. The stabilization of average keratometric corneal astigmatism in keratometry, average anterior chamber depth, and CCT was achieved after the second postsurgical week. Conclusion: It may be possible to prescribe glasses starting from two weeks after an uneventful phacoemulsification cataract surgery for most patients.

Comparison of Anterior Segment Measurements between Dual and Single Scheimpflug Camera

Purpose: To assess the degree of agreement of two rotating Scheimpflug cameras, Galilei G6 and Pentacam HR, in measuring corneal refractive power (K), anterior chamber depth (ACD), and central corneal thickness (CCT). Methods: Measurement agreement was assessed in 40 eyes of 40 outpatients at our hospital. Measurements of anterior and posterior corneal refractive power (K), ACD, and CCT were compared between the Galilei G6 and Pentacam HR. Results: For Galilei G6 (4 mm), Pentacam HR (3 mm) and Pentacam HR (4 mm), the anterior corneal refractive powers (K) were 44.35 ± 1.38 D, 44.09 ± 1.32 D, and 44.12 ± 1.35 D, respectively, and the posterior corneal refractive powers (K) were 6.39 ± 0.23 D, 6.45 ± 0.23 D, 6.45 ±0.22 D. The differences in the results were statistically significant. The average ACD measurements using Galilei G6 and Pentacam HR were 3.26 ± 0.42 mm and 3.17 ± 0.42 mm, respectively, and the average CCT measurements were 556.65 ± 30.12 μm and 553.78 ± 29.42 μm. The differences in the measurements were statistically significant. In addition, ACD 95% limits of agreement (LoA) between Galilei G6 and Pentacam HR were in the range of -0.14~0.32 mm, and CCT 95% LoA were in the range of -12.54~18.29 μm. Conclusions: There were significant differences in measurements of anterior and posterior corneal refractive power (K), ACD, and CCT between the two cameras. Agreement analysis suggests that Galilei G6 and Pentacam HR should not be used interchangeably. J Korean Ophthalmol Soc 2016;57(7):1056-1062

Ultrasound biomicroscopy in patients with unilateral pseudoexfoliation.

To compare the anterior segment morphology evaluated using ultrasound biomicroscopy (UBM) in patients with clinical pseudoexfoliation syndrome (XFS) in one eye and no clinical XFS in the fellow eye. Thirty patients with unilateral XFS were included in the study. All patients underwent evaluation of their anterior segment using UBM with and without dilatation with 1% cyclopentolate. The anterior chamber depth (ACD), lens thickness (LT), anterior chamber angle (ACA), ciliary body thickness (CBT), scleral thickness (ST), trabeculae -ciliary processes distance (T-CPD), and iris-ciliary processes distance (I-CPD) were measured using UBM scans. All results between the eyes with clinical XFS and their fellow eyes without clinical XFS were then compared. Before dilatation the eyes with XFS (4.350±0.531 mm) were found to have a significantly thicker lens (P=0.002) than the eyes without XFS (4.238±0.540 mm). In addition after dilatation, the eyes with XFS (4.310±0.500 mm) were found to have a significantly thicker lens than the eyes without XFS (4.160±0.480 mm) (P=0.019). The average ACD, for the group with XFS, comparing pre-dilatation (2.616±0.349 mm) and post-dilatation measurements (2.714±0.413) was found to be statistically increased (P=0.014). The average ACD, comparing pre-dilatation to post-dilatation measurements in patients without XFS (2.680±0.360), (2.720±0.500) was found to be statistically unchanged (P=0.450). Crystalline lenses tended to be thicker in the eyes with clinical pseudoexfoliation than their fellow eyes without pseudoexfoliation.

Kammerwinkelbeurteilung im klinischen Alltag – ein Vergleich zwischen der optischen Kohärenztomografie und der Gonioskopie

In glaucoma the structures of the anterior chamber are important for classification, therapy, progression and prognosis. In this context anterior segment optical coherence tomography (AS-OCT) gains more relevance. This study compares AS-OCT with gonioscopy in diagnostic performance of chamber angle (CA) assessment. 104 consecutive subjects with glaucoma underwent AS-OCT imaging using the Visante OCT. RESULTS were compared to gonioscopic grading from patient history using the Shaffer system. In addition, anterior chamber depth (ACD) assessment using slitlamp examination was evaluated as a prognostic factor for chamber angle width (CAW) and verified by AS-OCT measurement. Average CAW was 29° (AS-OCT). 17 % of the CAs that were "wide" in gonioscopy (variance 5-55°), showed a "narrow" CA in AS-OCT. 35 % of the CAs that were "narrow" in gonioscopy (variance 0-39°) showed a "wide" CA in AS-OCT. ACD assessment using slitlamp examination is a good predictor for CAW. In this context the technique provides equal informative value as gonioscopy. In cases of "wide" ACDs it is even superior. The critical ACD for an increased risk of angle closure is 2.4 mm. Concerning the critical ACD (< 2.4 mm) the technique gave the possibility to estimate, whether the patients were in the crucial range or not. Average ACD was 2.7 mm (AS-OCT). A strong correlation (correlation coefficient 0.83) between ACD and CAW was observed. Variation of 1 mm in the ACD leads to a change of 18.9° in the CAW. All patients with angle closure glaucoma were below this threshold and 74 % of patients with critical ACD had "narrow" (AS-OCT) CAs. In the case of routine clinical practice with inexperienced residents or circumstances that make gonioscopy difficult or impossible, optical coherence tomography is an effective alternative to the gold standard and is to some extent even superior.

Agreement between Orbscan II, VuMAX UBM and Artemis-2 very-high frequency ultrasound scanner for measurement of anterior chamber depth

BackgroundThe aim was to compare the anterior chamber depth (ACD) measurements taken with Orbscan II, ultrasound biomicroscopy (UBM) and the Artemis-2 VHF (very-high-frequency) ultrasound scanner in normal subjects.MethodsIn this prospective study, one eye from each of 60 normal subjects was randomly selected. Three subjects dropped out of the study because they were apprehensive about the UBM examination; their data were excluded entirely. Measurements of ACD were taken with the Orbscan II, UBM and Artemis-2 VHFUS. Results were obtained for coefficient of variance (CV) and intra-class correlation coefficient (ICC), and statistical analysis was by repeated-measures analysis of variance (ANOVA) for intra-observer repeatability. ANOVA and Bland–Altman analyses were used to determine limits of agreement (LOA) between the three instruments.ResultsThe average ACD (± standard deviation) was 3.13 ± 0.34 mm, 2.96 ± 0.27 mm and 2.87 ± 0.31 mm for the Orbscan II, UBM and Artemis-2 VHFUS, respectively. The repeatability scores were 0.015 ± 0.014%, 0.08 ± 0.09% and 0.07 ± 0.06% for the Orbscan II, UBM and Artemis-2 VHFUS, respectively. The ICC for repeatability of Orbscan II, UBM and Artemis-2 VHFUS measurements was high and equal to 0.99%. The intra-observer repeatability scores of the ACD measurement p-values using Orbscan II, UBM and Artemis-2 VHFUS were 0.12, 0.70 and 0.10, respectively. The mean difference and standard deviations for ACD measurements using Orbscan II vs UBM, Orbscan II vs Artemis-2 VHFUS and UBM vs Artemis-2 VHFUS were 0.17 ± 0.31 mm, 0.27 ± 0.34 mm and 0.10 ± 0.18 mm, respectively. LOAs were 0.78 to -0.44 mm, 0.93 to -0.39 mm and 0.45 to -0.26 mm. ANOVA revealed a statistically significant difference between the Orbscan II, UBM and Artemis-2 VHFUS (p < 0.0001).ConclusionsMeasurements by the three instruments show high repeatability. UBM and the Artemis-2 VHFUS can be used interchangeably, but the Orbscan II cannot be used interchangeably with UBM or the Artemis-2 VHFUS.

Normative Values and Contralateral Comparison of Anterior Chamber Depth Measured by Orbscan II in an Iranian Population

Purpose: The objective of study was (i) to determine the normative values of anterior chamber depth (ACD) with Orbscan II Topography System and (ii) to compare right and left eyes data in the normal young population. Methods: A total of 1001 healthy participants aged 18-45 years participated in this observational cross-sectional study. The study population consisted of 616 female and 385 male subjects. The ACD was measured with the Orbscan II. In our study, ACD was defined as the distance between the corneal epithelium and the anterior lens surface. The differences between genders, between right and left eyes and age-related changes were evaluated. Statistical analyses were performed using student t test. Results: The average ACD in our study population was recorded as 3.653 ± 0.306 mm (median: 3.670 mm, mode: 3.70 mm, minimum: 2.35 mm and maximum: 6.60 mm, 95% Confidence interval: 3.640 to 3.666). The ACD was 3.64±0.30 mm in males and 3.67±0.32 mm in females which was statistically different between genders (P &lt; 0.01). There was a much similarity in ACD values in both eyes. ACD was decreased with age (r= -0.250, p&lt;0.001). Conclusion: Detailed description and analysis of ACD with Orbscan demonstrated that the obtained average value of ACD was higher in female than male and decreased slightly with increasing age. There was no difference between the eyes.

Anterior Chamber Morphology Before and After Laser Peripheral Iridotomy Determined by Scheimpflug Technology in White Patients With Narrow Angles

To investigate the changes of anterior segment morphology in patients with narrow angles using a rotating Scheimpflug camera before and after laser peripheral iridotomy (LPI). Forty-six eyes of 46 patients classified as primary angle closure suspect, primary angle closure, primary angle closure glaucoma, acute angle closure glaucoma, fellow eyes of acute angle closure glaucoma, and iris plateau configuration were enrolled in this prospective interventional case series. Anterior chamber volume (ACV), anterior chamber depth (ACD), and anterior chamber angle (ACA) were evaluated with an Scheimpflug camera, before and after LPI. After LPI, the average anterior chamber depth increased from 1.88 ± 0.36 to 1.93 ± 0.32 mm (P=0.49). The mean ACV increased from 74.6 ± 25 to 89.4 ± 21.1 mm (P=0.003). The average ACA increased from 21.1 ± 4.8 to 23.4 ± 3.8 degrees (P=0.01). Eyes with synechial angle closure (primary angle closure and primary angle closure glaucoma) demonstrated a significantly smaller change in ACV compared with eyes with appositional angle closure (primary angle closure suspect). ACV and ACA determined by Scheimpflug technology increase to a statistically significant degree and this change appears to be more pronounced in cases of appositional angle closure.

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 short-term 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.

Postoperative hyperopic shift after cataract surgery in silicone oil‐filled eyes

Vitrectomy with silicone oil (SO) instillation has been widely used in complicated vitreoretinal diseases to achieve retina stability. Because progressive lens opacity is common after vitrectomy and SO infusion, the removal of SO and cataract extraction with intra-ocular lens (IOL) implantation may be performed in the same setting. The refractive outcomes of cataract surgery with simultaneous SO removal have shown acceptable results. However, the refractive outcome after cataract surgery is less predictable in some complicated cases in which intravitreal SO is retained to achieve a long-term tamponade effect. We investigate the refractive outcome of cataract surgery in 21 SO-filled eyes with complicated vitreoretinal diseases and compare the results with those in 42 vitrectomized eyes without SO instillation. The SO used in our study was 5000 centistokes. Axial length (AL) measurements were performed using contact A-scan echography (Sonomed A-2500, New York, NY, USA). To adjust the falsely elongated AL due to the low sound velocity in SO, the following formula was used: AL = anterior chamber depth + lens thickness + vitreous length *0.68. IOL power was calculated using the SRK-T formula. In all SO-filled eyes, we generally chose a more myopic calculated target refraction when deciding the IOL power to compensate for the possible hyperopic shift due to a higher refractive index of SO (Stefansson et al. 1988; Smith et al. 1990; Hotta & Sugitani 2005). Foldable acrylic IOLs (AcrySof SA60AT for power ≧6 D or AcrySof MA60MA for power<6 D; Alcon Surgery) were implanted into the capsular bag in all eyes. Intergroup comparison was shown in Table 1. The refractive outcomes in the SO-filled group were more variable (1.07 ± 2.26 D versus −0.57 ± 1.15 D) and showed a significant tendency of hyperopic shift (+2.89 ± 2.15 D versus + 0.04 ± 1.0 D, p < 0.001). Eyes in the SO-filled group had a higher proportion of cases undergoing scleral buckling procedure, a shorter anterior chamber depth (ACD) and a longer adjusted AL in average. In one eye in the SO-filled group, the refraction changed from +3.25 D after cataract surgery to 0 D after SO removal 3 years later. The uncertainty of postoperative refraction after cataract surgery in SO-filled eyes is due to several perioperative factors. In our study, the SO-filled group had significantly longer average AL and shorter average ACD, which might be related to a higher rate of scleral buckling procedure performed in those eyes. A longer AL could augment the SO-induced acoustic signal attenuating effect and make the measurement less reliable (Ghoraba et al. 2002). Previous studies found that a hyperopic shift in refraction would be induced when vitreous was replaced with SO through vitrectomy in phakic or pseudophakic eyes (Stefansson et al. 1988; Smith et al. 1990; Hotta & Sugitani 2005). This tendency of SO-induced hyperopic shift was also noted in our study. However, the amount of hyperopic shift showed great variation among different studies. The posterior convex curvature of the IOL is thought to be related to the amount of hyperopic shift (Hotta & Sugitani 2005). Incomplete SO filling in the vitreous cavity causing changes in curvature and contact area of SO-fluid interface in different head positions may also result in variability in refractions and AL measurement (Dick et al. 1997). In conclusion, the refractive results of cataract surgery in SO-filled eyes were generally more variable than in simply vitrectomized eyes. Because a mean hyperopic shift is about 3.0 D in our study, we suggest choosing −2.5 to − 3.0 D target refraction, which may partially compensate for the SO-induced hyperopic shift, if SO is intended to be left for a long-term tamponade effect.

Three-Dimensional Evaluation of Accommodating Intraocular Lens Shift and Alignment In Vivo

To quantify 3-dimensionally the anterior segment geometry, biometry, and lens position and alignment in patients before and after implantation of the Crystalens-AO (Bausch & Lomb, Rochester, NY) accommodating intraocular lens (A-IOL). Prospective, observational study. Ten patients (20 eyes) with cataract before and after implantation of the Crystalens-AO A-IOL. Custom full anterior segment 3-dimensional (3-D) spectral optical coherence tomography (OCT) provided with quantification tools was used to image the cornea, iris, and natural lens preoperatively and intraocular lens postoperatively. Measurements were obtained under phenylephrine preoperatively and under natural viewing conditions and phenylephrine (for accommodative efforts ranging from 0 to 2.5 diopters [D]) and pilocarpine postoperatively. Three-dimensional quantitative anterior segment images, corneal geometry and power, anterior chamber depth (ACD), lens thickness, pupil diameter, A-IOL shift with accommodative effort or drug-induced accommodation, and A-IOL alignment. Crystalline lens and IOLs were visualized and quantified 3-dimensionally. The average ACD were 2.64±0.24 and 3.65±0.35 mm preoperatively and postoperatively (relaxed state), respectively, and they were statistically significantly correlated (although their difference was not statistically correlated with lens thickness). The A-IOL did not shift systematically with accommodative effort, with 9 lenses moving forward and 11 lenses moving backward (under natural conditions). The average A-IOL shift under stimulated accommodation with pilocarpine was-0.02±0.20 mm. The greatest forward shift occurred bilaterally in 1 patient (-0.49 mm in the right eye and-0.52 mm in the left eye, under pilocarpine). The high right/left symmetry in the horizontal tilt of the crystalline lens is disrupted on IOL implantation. Accommodative IOLs tend to be slightly more vertically tilted than the crystalline lens, with increasing tendency with accommodative effort. Two subjects showed postoperative IOL tilts >9 degrees. Changes in pupillary diameter correlated with pilocarpine-induced A-IOL axial shift. Intermediate accommodative demands (1.25 D) elicited the greater shifts in axial A-IOL location and tilt and pupil diameter. Quantitative 3-D anterior segment OCT allows full evaluation of the geometry of eyes implanted with A-IOLs preoperatively and postoperatively. High-resolution OCT measurements of the Crystalens 3-D positioning revealed small (and in many patients backward) A-IOL axial shifts with both natural or drug-induced accommodation, as well as tilt changes with respect to natural lens and accommodative effort.

Anterior Segment Optical Coherence Tomography for the Quantitative Evaluation of the Anterior Segment Following Boston Keratoprosthesis

ObjectiveTo quantitatively evaluate the anterior segment using anterior segment optical coherence tomography (AS-OCT) following Boston keratoprosthesis type 1.MethodsA retrospective study consisted of AS-OCT imaging at a single time point postoperatively in 52 eyes. Main outcomes measures include anatomical and functional anterior chamber depth (ACD), angle (ACA) and peripheral and proximal synechiae.ResultsThe mean time point of imaging was 19.3 months postoperatively. Average anatomical and functional ACD was 2.0 and 0.21 mm respectively, and mean ACA ranged from 2.5° to 6.14° in representative meridians. An average of 8.7 clock hours of angle closure was observed in the 25 eyes in which all meridians were imaged. The majority of eyes showed peripheral (86.5%) and proximal (67.3%) synechiae.ConclusionsAS-OCT is a useful tool for quantitative evaluation of anterior segment and angle after keratoprosthesis, which is otherwise poorly visible. The majority of eyes showed shallow ACD, extensive angle closure and synechiae formation.

The effect of pharmacologic pupillary dilatation on anterior segment parameters in patients with exfoliation syndrome

PurposeThe purpose of this study was to evaluate the effect of pharmacologic pupillary dilatation on anterior chamber depth (ACD) and anterior chamber angle (ACA) in eyes with exfoliation syndrome (XFS). MethodsThirty-six eyes of 36 patients with XFS were evaluated with slit-lamp examination, Goldmann applanation tonometry and ultrasound biomicroscopy (UBM) under standard light conditions. Primary outcome parameters were defined as the change in ACD and ACA measured before and 40min after instillation of a single drop of either 1% cyclopentolate (Group I; n=12), 2.5% phenylephrine (Group II; n=12) or 1% tropicamide (Group III; n=12). Change in intraocular pressure (IOP) during the same time interval was included as a secondary outcome measure. ResultsThe average predilatation ACD, ACA and IOP values in the study subjects were 2.54±0.40mm, 27.9±6.3° and 14.9±3.1mmHg, respectively. There were no significant differences in the mean age (p=0.461), the female/male ratio (p=0.232), baseline ACD (p=0.841), ACA (p=0.761) or IOP (p=0.070) within the three groups. Differences in dilation induced changes in ACD (p=0.108), ACA (p=0.636) and IOP (p=0.160) between the three groups were not statistically significant. ConclusionPupillary dilatation with a single drop of 1.0% cyclopentolate, 2.5% phenylephrine or 1% tropicamide is not associated with shallowing of the anterior chamber or narrowing of the ACA in patients with XFS who present with open angles.