Ultrasonographic biomicroscopy, Scheimpflug photography, and novel provocative tests in contralateral eyes of Chinese patients initially seen with acute angle closure

Efficacy and Safety of Different Types of Intraocular Pressure-Lowering Surgeries in Patients with Primary Angle Closure (PAC) or PAC Glaucoma: Systematic Review and Network Meta-Analysis of Randomized Clinical Trials

OBJECTIVE

To compare the intraocular pressure (IOP)-lowering effect of different types of surgery available in the literature using a network meta-analysis (NMA) based on a systematic review.

METHODS

PubMed and the Cochrane database were searched. Randomized clinical trials involving surgical interventions for high IOP for PAC (primary angle closure) or PACG (primary angle closure glaucoma) were included. Descriptive statistics and outcomes were extracted. Bayesian NMA was performed to compare the IOP-lowering effect and the change in the number of antiglaucoma drugs required between baseline and endpoint, as well as success rates.

RESULTS

This NMA included 21 articles with 1237 eyes with PAC or PACG. Interventions were characterised as phacoemulsification (phaco), trabeculectomy, goniosynechialysis (GSL) with viscoelastic or blunt device, goniosurgery (GS) (trabeculotomy or goniotomy), micro-bypass stent (Istent®), endocyclophotocoagulation (ECPL) or various combinations of these procedures. Phaco+GSL [-1.73 (95%CrI: -3.53 to -0.13)] and phaco+GSL+GS [-3.92 (95%CrI: -6.91 to -1.31)] provided better IOP lowering effects than phaco alone. Phaco+trabeculectomy [-3.11 (95%CrI: -5.82 to -0.44)] was inferior to phaco+GSL+GS. Phaco+trabeculectomy [-0.45 (95%CrI: -0.81 to -0.13)] provided a better outcome in terms of reducing the need for antiglaucoma drug compared to phaco alone. There were no differences between the other surgeries in terms of reduction of antiglaucoma drug number and IOP lowering effect. Success rates were similar for all surgical procedures.

CONCLUSIONS

Phaco+GSL+GS showed the most promising results for lowering IOP. Phaco+trabeculectomy resulted in a significant reduction in the number of antiglaucoma drugs compared to phaco alone.

Rethinking Prophylactic Laser Peripheral Iridotomy in Primary Angle-Closure Suspects: A Review

PURPOSE

To examine the generalizability, discuss limitations, and critically appraise recommendations on the management of primary angle-closure suspects (PACSs) that emerged as a result of recent randomized clinical trials challenging the widely accepted clinical practice of offering laser peripheral iridotomy (LPI) to PACS patients. To synthetize findings from these and other studies.

DESIGN

Narrative review.

SUBJECTS

Patients classified as PACS.

METHODS

The Zhongshan Angle-Closure Prevention (ZAP)-Trial and the Singapore Asymptomatic Narrow Angle Laser Iridotomy Study (ANA-LIS) along with accompanying publications were reviewed. Epidemiologic studies reporting on the prevalence of primary angle-closure glaucoma and other precursor forms of the disease were also analyzed along with publications reporting on the natural course of the disease or studies reporting on outcomes after prophylactic LPI.

MAIN OUTCOME MEASURES

Incidence of progression to more severe forms of angle closure.

RESULTS

Patients recruited in recent randomized clinical trials are asymptomatic, do not have cataracts, may be younger, and have, on average, deeper anterior chambers depth compared with patients treated with LPI in clinics.

CONCLUSIONS

The ZAP-Trial and ANA-LIS clearly represent the best available data on PACS management, additional parameters however may need to be considered when physicians face patients in clinic. PACS patients encountered at tertiary referral centers may represent more advanced cases with respect to ocular biometric parameters and may be at higher risk for disease progression compared with those recruited through population-based screening.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Detection of Nocturnal Elevation in Intraocular Pressure Using a Home Tonometer in a Patient With Iridocorneal Endothelial Syndrome

We report on a patient with iridocorneal endothelial (ICE) syndrome in whom intraocular pressure (IOP) elevation during the night was detected using a home tonometer. A 44-year-old woman was diagnosed with ICE syndrome in the left eye. Angle-closure attack-like symptoms, including blurred vision and headache, appeared and spontaneously resolved irregularly at bedtime. Daytime examination indicated normal IOP and no obvious signs of glaucoma such as visual field defects or fundus abnormalities. However, nocturnal IOP measurements using a home tonometer revealed temporary high IOP at the time of symptom onset. A home tonometer may be a useful tool to detect transient IOP elevation at night, even if the IOP is normal during daytime examinations.

Dynamic analysis of iris changes and a deep learning system for automated angle-closure classification based on AS-OCT videos

Background

To study the association between dynamic iris change and primary angle-closure disease (PACD) with anterior segment optical coherence tomography (AS-OCT) videos and develop an automated deep learning system for angle-closure screening as well as validate its performance.

Methods

A total of 369 AS-OCT videos (19,940 frames)—159 angle-closure subjects and 210 normal controls (two datasets using different AS-OCT capturing devices)—were included. The correlation between iris changes (pupil constriction) and PACD was analyzed based on dynamic clinical parameters (pupil diameter) under the guidance of a senior ophthalmologist. A temporal network was then developed to learn discriminative temporal features from the videos. The datasets were randomly split into training, and test sets and fivefold stratified cross-validation were used to evaluate the performance.

Results

For dynamic clinical parameter evaluation, the mean velocity of pupil constriction (VPC) was significantly lower in angle-closure eyes (0.470 mm/s) than in normal eyes (0.571 mm/s) (P < 0.001), as was the acceleration of pupil constriction (APC, 3.512 mm/s²vs. 5.256 mm/s²; P < 0.001). For our temporal network, the areas under the curve of the system using AS-OCT images, original AS-OCT videos, and aligned AS-OCT videos were 0.766 (95% CI: 0.610–0.923) vs. 0.820 (95% CI: 0.680–0.961) vs. 0.905 (95% CI: 0.802–1.000) (for Casia dataset) and 0.767 (95% CI: 0.620–0.914) vs. 0.837 (95% CI: 0.713–0.961) vs. 0.919 (95% CI: 0.831–1.000) (for Zeiss dataset).

Conclusions

The results showed, comparatively, that the iris of angle-closure eyes stretches less in response to illumination than in normal eyes. Furthermore, the dynamic feature of iris motion could assist in angle-closure classification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40662-022-00314-1.

A comparison of lens parameters in patients with various subtypes of primary angle-closure disease and the normal population: A prospective study

Purpose:

To assess the role of lens parameters in the detection and progression of primary angle-closure disease (PACD) by combining A-scan and A-scan optical coherence tomography (AS-OCT) parameters.

Methods:

A cross-sectional study was conducted in a tertiary health-care center in eastern India. A total of 91 study subjects including cases and controls were included in the study. The parameters studied were lens thickness (LT), lens axial factor (LAF), relative lens position (RLP), and lens vault (LV). Anterior chamber depth (ACD) and axial length (AL) were also analyzed using A-scan.

Results:

The LT was significantly more in all subtypes of PACD (from 4.24 ± 0.84 to 5.02 ± 0.18 mm) than in controls (4.04 ± 0.46 mm; P < 0.01). Similarly, LAF was significantly less among all subtypes of PACD compared to controls (P < 0.001). The RLP, calculated using the formula (ACD + 0.5 LT)/AL × 10, showed no significant difference (P > 0.05) between various study groups. The LV in acute angle-closure glaucoma (AcCG) patients was significantly higher compared to the control population (P < 0.01). Ocular parameters like ACD decreased, whereas LT and LAF increased from normal through primary angle closure (PAC) to primary angle-closure glaucoma (PACG). Logistic regression analysis found a significant association between a decrease in ACD and an increased risk of PACG (P-value was 0.0001) and an increase in LT and LAF with increased risk of PACG (P = 0.040 and P = 0.006, respectively).

Conclusion:

Inclusion of lens parameter assessment in the workup of a patient with PACD helps in detection and close monitoring of the progression from suspected to disease state.

Anterior Chamber Angle Changes in Primary Angle-closure Glaucoma Following Phacoemulsification Versus Phacotrabeculectomy: A Prospective Randomized Clinical Trial

PRCIS

We used anterior segment optical coherence tomography to investigate anterior chamber angle in primary angle-closure glaucoma (PACG) eyes following phacoemulsification and phacotrabeculectomy. Angle widening was significantly greater after phacoemulsification up to 6 months after the surgery.

PURPOSE

To compare anterior chamber angle following 2 common surgeries for PACG.

METHODS

One hundred ten glaucoma patients were evaluated in this single center, prospective, randomized clinical trial. Those with concomitant PACG and senile cataract and without a history of ocular surgery, trauma, or chronic miotic use were recruited. Monocular patients were also excluded. Finally, 52 eligible subjects were randomly assigned to phacoemulsification ("Phaco" group, 25 eyes) or phacotrabeculectomy ("Combined" group, 27 eyes) surgeries. A swept-source, anterior segment optical coherence tomography device (CASIA SS-1000 OCT) was used to image the anterior segment. Mask graders used the images to measure the following parameters before and 1 week, 1 month, and 6 months after surgery: angle opening distance at 500 µm, trabecular iris surface area at 500 µm, and trabecular iris angle at 500 µm.

RESULTS

There was no significant difference between study groups regarding best-corrected visual acuity, intraocular pressure (IOP), and the number of glaucoma medications in preoperative or postoperative visits (P>0.076). Also, the measured angle parameters were not statistically significantly different between the 2 groups before surgery (P>0.123). After surgery, all measured parameters were significantly increased in both groups (P<0.0001). At the 6-month follow-up, nasal angle opening distance at 500 µm was 0.383±0.027 vs. 0.349±0.017, trabecular iris surface area at 500 µm was 0.141±0.007 vs. 0.125±0.005, and trabecular iris angle at 500 µm was 40.1±12.9 vs. 34.6±3.1 in Phaco and Combined groups, respectively (P<0.0001 for all).

CONCLUSIONS

Anterior chamber angle widening by anterior segment optical coherence tomography was observed in PACG patients following surgery and was significantly greater after phacoemulsification compared with combined phacotrabeculectomy at all time points. Similar IOP and medication burden were noted for up to 6 months as secondary outcomes. The contribution of angle changes to the IOP-lowering effect of phacoemulsification in PACG eyes needs further study.

Changes in Iris Stiffness and Permeability in Primary Angle Closure Glaucoma

Purpose

To evaluate the biomechanical properties of the iris by evaluating iris movement during pupil constriction and to compare such properties between healthy and primary angle-closure glaucoma (PACG) subjects.

Methods

A total of 140 subjects were recruited for this study. In a dark room, the anterior segments of one eye per subject were scanned using anterior segment optical coherence tomography imaging during induced pupil constriction with an external white light source of 1700 lux. Using a custom segmentation code, we automatically isolated the iris segments from the AS-OCT images, which were then discretized and transformed into a three-dimensional point cloud. For each iris, a finite element (FE) mesh was constructed from the point cloud, and an inverse FE simulation was performed to match the clinically observed iris constriction in the AS-OCT images. Through this optimization process, we were able to identify the elastic modulus and permeability of each iris.

Results

For all 140 subjects (95 healthy and 45 PACG of Indian/Chinese ethnicity; age 60.2 ± 8.7 for PACG subjects and 57.7 ± 10.1 for healthy subjects), the simulated deformation pattern of the iris during pupil constriction matched well with OCT images. We found that the iris stiffness was higher in PACG than in healthy controls (24.5 ± 8.4 kPa vs. 17.1 ± 6.6 kPa with 40 kPa of active stress specified in the sphincter region; P < 0.001), whereas iris permeability was lower (0.41 ± 0.2 mm2/kPa s vs. 0.55 ± 0.2 mm2/kPa s; p = 0.142).

Conclusions

This study suggests that the biomechanical properties of the iris in PACG are different from those in healthy controls. An improved understanding of the biomechanical behavior of the iris may have implications for the understanding and management of angle-closure glaucoma.

Analyzing Anatomical Factors Contributing to Angle Closure Based on Anterior Segment Optical Coherence Tomography Imaging

PURPOSE

To analyze anatomical factors contributing to angle closure based on anterior segment optical coherence tomography (AS-OCT) imaging.

METHODS

A total of 238 patients with angle closure and 1122 normal controls were consecutively recruited for this study. Participants' eyes were imaged using AS-OCT under the same darkened ambient light conditions. The following parameters were analyzed: central anterior chamber depth (ACD); anterior chamber area (ACA); anterior chamber volume (ACV), anterior chamber width (ACW); corneal diameter (CD); posterior cornea curvature (PCC); anterior cornea curvature (ACC); maximum iris thickness (ITM); iris thickness at 750 um (IT750) and 2000 um (IT2000) from the scleral spur; iris curvature (IC); iris area (IA); lens vault (LV); angle opening distance (AOD); trabecular iris space area at 500 um (TISA500) and 750 um (TISA750) from the scleral spur; angle recess area (ARA). Lasso regression models were used to detect the collinearity of parameters. The multivariable logistic regression was performed to determine the independent association between angle closure and those parameters included in Lasso regression model. Also Factor analysis was performed to extract a few underlying factors (components) from these parameters.

RESULTS

Lasso regression showed that ACD, ACV, PCC, IT750, IT2000 and LV were screened in the model. The multivariable logistic regression indicated that ACV, PCC, IT750 and LV were significantly associated with angle closure. Factor analyses revealed that 4 factors, each with its closely associated clusters of variables, produced the best results: ACA, ACV and ACD (Factor 1); LV, tIC and nIC, (Factor 2); ACW, CD and PCC (Factor 3); and tITM, tIT2000, tIT750, nIT2000 and nIT750 (Factor 4).

CONCLUSIONS

Four separate mechanisms were showed to be involved in the pathogenesis of angle closure, from anterior chamber dimensions, lens, iris and cornea respectively. The parameters ACV, PCC, IT750, and LV are more predominant in determining angle closure.

The Singapore Asymptomatic Narrow Angles Laser Iridotomy Study: Five-Year Results of a Randomized Controlled Trial

PURPOSE

To examine the efficacy of laser peripheral iridotomy (LPI) in patients who received a diagnosis of primary angle-closure suspect (PACS).

DESIGN

Prospective, randomized controlled trial.

PARTICIPANTS

This multicenter, randomized controlled trial (ClinicalTrials.gov identifier, NCT00347178) enrolled 480 patients older than 50 years from glaucoma clinics in Singapore with bilateral asymptomatic PACS (defined as having ≥2 quadrants of appositional angle closure on gonioscopy).

METHODS

Each participant underwent prophylactic LPI in 1 randomly selected eye, whereas the fellow eye served as a control. Patients were followed up yearly for 5 years.

MAIN OUTCOME MEASURES

The primary outcome measure was development of primary angle closure (PAC; defined as presence of peripheral anterior synechiae, intraocular pressure [IOP] of >21 mmHg, or both or acute angle closure [AAC]) or primary angle-closure glaucoma (PACG) over 5 years.

RESULTS

Of the 480 randomized participants, most were Chinese (92.7%) and were women (75.8%) with mean age of 62.8 ± 6.9 years. Eyes treated with LPI reached the end point less frequently after 5 years (n = 24 [5.0%]; incidence rate [IR], 11.65 per 1000 eye-years) compared with control eyes (n = 45 [9.4%]; IR, 21.84 per 1000 eye-years; P = 0.001). The adjusted hazard ratio (HR) for progression to PAC was 0.55 (95% confidence interval [CI], 0.37-0.83; P = 0.004) in LPI-treated eyes compared with control eyes. Older participants (per year; HR, 1.06; 95% CI, 1.03-1.10; P < 0.001) and eyes with higher baseline IOP (per millimeter of mercury; HR, 1.35; 95% CI, 1.22-1.50; P < 0.0001) were more likely to reach an end point. The number needed to treat to prevent an end point was 22 (95% CI, 12.8-57.5).

CONCLUSIONS

In patients with bilateral asymptomatic PACS, eyes that underwent prophylactic LPI reached significantly fewer end points compared with control eyes over 5 years. However, the overall incidence of PAC or PACG was low.

Phacoemulsification versus Phacotrabeculectomy in Medically Controlled Primary Angle Closure Glaucoma with Cataract in an Indian Cohort: A randomized controlled trial

PURPOSE

To compare the outcomes of phacoemulsification with phacotrabeculectomy in primary angle closure glaucoma (PACG) eyes with medically controlled intraocular pressure (IOP).

METHODS

Prospective, randomized control trial including 33 eyes of 33 patients who underwent phacoemulsification (Phaco) and 37 eyes (37 patients) who underwent phacotrabeculectomy (PT). The primary outcome measure was survival defined as IOP control (IOP ≥ 6 and ≤ 21 mmHg without antiglaucoma medications (AGM) at different time points. Secondary outcome measures were the rate of visual recovery and complications.

RESULTS

The mean age in years (PT: 58.5 ± 9.8, Phaco:61.6 ± 8.9; p = 0.16), preoperative mean deviation in decibel (PT: -18.7 ± 9.3; Phaco: -16.6 ± 7.9; p = 0.32) and the mean follow up in years (PT: 2.5 ± 1.8; Phaco: 2.8 ± 2.0; p = 0.63) were similar in the two groups. The mean preoperative AGMs were more in the PT group (PT: 2.13 ± 0.97, Phaco: 1.60 ± 0.78; p = 0.01). In both the groups the survival was similar at all-time points (PT: 78% at 1-year and 52% at 5-years, Phaco: 80% at 1 year and 59% at 5 years (P = 0.82). The postoperative visual acuity in LogMAR was significantly better in the Phaco group at 1 month (PT: 0.22 ± 0.38, Phaco:0.06 ± 0.07; p = 0.02). Postoperative AGM (p = 0.68) and rate of visual field progression PT: -0.46 ± 0.41 dB/year; Phaco: -0.38 ± 0.73 dB/year; p = 0.67) were similar in both groups. One eye in PT group developed malignant glaucoma which resolved with laser hyaloidotomy and cycloplegic therapy.

CONCLUSIONS

More rapid visual recovery with similar IOP control and similar visual field stability favor phacoemulsification to phacotrabeculectomy in medically controlled PACG eyes with cataract.

Phacoemulsification with Goniosynechialysis versus Phacoemulsification Alone in Angle-Closure Glaucoma: A Meta-Analysis of Randomized Controlled Trials

Purpose

This meta-analysis aimed to compare the efficacy and safety of phacoemulsification with goniosynechialysis (Phaco-GSL) with those of phacoemulsification alone (Phaco-alone) in patients with angle-closure glaucoma and cataract.

Methods

Randomized controlled trials (RCTs) were selected through a search of electronic databases. Trial eligibility and risk of bias were assessed using Cochrane review methods. Primary measures included the intraocular pressure (IOP), number of antiglaucoma medications, peripheral anterior adhesion (PAS) extent, and their pre- and postoperative changes. For continuous parameters, we calculated weighted mean differences and 95% confidence intervals. Statistical analysis was performed using RevMan 5.3 software.

Results

Eight RCTs were included, where 224 and 236 eyes were in the Phaco-GSL and Phaco-alone groups, respectively. Both postoperative IOP and number of medications were not significantly different between the study groups at the six- and twelve-month follow-up. However, the 12-month postoperative PAS extent was significantly smaller in the Phaco-GSL group than in the Phaco-alone group. Similarly, changes from the preoperative to 12-month postoperative PAS extent were significantly greater in the Phaco-GSL group than in the Phaco-alone group, but IOP and the number of medication changes were not different.

Conclusions

Our results provide evidence that Phaco-GSL provides advantages over Phaco-alone treatment regarding PAS reduction. In terms of IOP and medication reduction, both groups were comparable. Thus, Phaco-GSL can be considered for the treatment of patients with angle-closure glaucoma and cataract due to its ease, safety, and potential benefit for the anterior chamber angle.

Peripheral Anterior Chamber Depth and Angle Measurements Using Pentacam After Implantation of Toric and Non-toric Implantable Collamer Lenses

Purpose: To evaluate the characteristics of peripheral anterior chamber measurements by Pentacam after posterior implantable collamer lenses (ICL) and toric ICL (TICL) with central hole (V4c) implantation.

Methods: Prospective, non-randomized consecutive case series. Forty-six patients undergoing ICL implantation in one eye (Group A) and identically sized TICL in the contralateral eye (Group B) in the Refractive Surgery Center of Eye and ENT Hospital of Fudan University were prospectively included. According to ICL/TICL size, these eyes were further divided into four subgroups. Peripheral anterior chamber depth (PACD) and angle (ACA) in nasal and temporal sides were measured using Pentacam pre-operatively and 12-month post-operatively.

Results: The safety indices were 1.34 ± 0.32 and 1.25 ± 0.16 and the efficacy indices were 1.20 ± 0.24 and 1.19 ± 0.19 for ICL and TICL groups, respectively. There was no significant difference in pre-operative PACD or ACA between the two groups. Post-operative PACD and ACA were significantly lower than pre-operative values. Variations of PACD and ACA of TICL group were significantly larger than those of ICL group. The change of ACA for 13.2 mm lenses was significantly larger than that of 12.6 mm lenses. Pre-operative CACD and vault were significantly associated with post-operative PACD, while pre-operative ACA and vault were significantly associated with post-operative ACA.

Conclusions: Variations of PACD and ACA were greater in eyes after TICL (V4c) implantation compared with identically sized ICL (V4c) implantation and with larger size than smaller size lens implantation. Pre-operative anterior chamber structure and vault affect post-operative PACD and ACA.

Factors associated with blindness three months following treatment for acute primary angle glaucoma

AIMS

To study the risk factors associated with blindness after treatment of acute primary angle closure (APAC), and to identify the critical time window to decrease rate of blindness.

METHODS

In this multicentre retrospective case series, 1030 consecutive subjects (1164 eyes) with APAC in China were recruited. The rates of blindness were analysed up to 3 months after treatment of APAC. A logistic regression was used to identify the risk factors associated with blindness, including age, gender, distance to hospital, rural or urban settings, treatment method, education level, time from symptom to treatment (TST, hours) and presenting intraocular pressure (IOP). The critical time window associated with a blindness rate of ≤1% was calculated based on a cubic function by fitting TST to the rate of blindness at each time point.

RESULTS

The rate of blindness after APAC was 12.54% after treatment. In multivariate regression, education level, TST and presenting IOP were risk factors for blindness (p=0.022, 0.004 and 0.001, respectively). The critical time window associated with a blindness rate of ≤1% was 4.6 hours.

CONCLUSIONS AND RELEVANCE

Education level, TST and presenting IOP were risk factors for blindness after APAC. Timely medical treatment is key in reducing blindness after APAC.

[Iris shape change and risk of anterior chamber angle closure]

Potential obstruction of the anterior chamber angle by iris root is a key factor of the pathogenesis of angle-closure glaucoma. Development and adoption of ultrasound biomicroscopy and optical coherence tomography in clinical practice have significantly expanded the capabilities of studying the structures of the anterior eye segment in terms of angle closure risk factors through improving visualization depth and quality of examination, including different variants of iris structure and potential changes of its shape in mydriasis. The article reviews various studies dedicated to the progression of primary angle-closure glaucoma and its dependence on the biometric parameters of the eye and changes in pupil size.

Mutations in SPATA13/ASEF2 cause primary angle closure glaucoma

Current estimates suggest 50% of glaucoma blindness worldwide is caused by primary angle-closure glaucoma (PACG) but the causative gene is not known. We used genetic linkage and whole genome sequencing to identify Spermatogenesis Associated Protein 13, SPATA13 (NM_001166271; NP_001159743, SPATA13 isoform I), also known as ASEF2 (Adenomatous polyposis coli-stimulated guanine nucleotide exchange factor 2), as the causal gene for PACG in a large seven-generation white British family showing variable expression and incomplete penetrance. The 9 bp deletion, c.1432_1440del; p.478_480del was present in all affected individuals with angle-closure disease. We show ubiquitous expression of this transcript in cell lines derived from human tissues and in iris, retina, retinal pigment and ciliary epithelia, cornea and lens. We also identified eight additional mutations in SPATA13 in a cohort of 189 unrelated PACS/PAC/PACG samples. This gene encodes a 1277 residue protein which localises to the nucleus with partial co-localisation with nuclear speckles. In cells undergoing mitosis SPATA13 isoform I becomes part of the kinetochore complex co-localising with two kinetochore markers, polo like kinase 1 (PLK-1) and centrosome-associated protein E (CENP-E). The 9 bp deletion reported in this study increases the RAC1-dependent guanine nucleotide exchange factors (GEF) activity. The increase in GEF activity was also observed in three other variants identified in this study. Taken together, our data suggest that SPATA13 is involved in the regulation of mitosis and the mutations dysregulate GEF activity affecting homeostasis in tissues where it is highly expressed, influencing PACG pathogenesis.

Diurnal Variation of Optical Coherence Tomography Measurements of Static and Dynamic Anterior Segment Parameters

PURPOSE

To examine the diurnal variation of static and dynamic anterior segment parameters in young, healthy eyes by comparing anterior segment optical coherence tomography (AS-OCT) measurements obtained in the morning and evening and also in the light and dark.

METHODS

Twenty-two subjects ranging from 19 to 47 years of age with no past ocular history were selected. Imaging was performed with the Tomey CASIA2 AS-OCT device in 2 fixed lighting environments, light and dark, between the hours of 08:30 to 10:00 and 17:30 to 19:00. Four AS-OCT images were analyzed per eye. Pupil diameter (PD), iris area (IA), iris curvature (IC), anterior chamber depth (ACD), lens vault (LV), anterior chamber width (ACW), anterior chamber area (ACA), angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), and trabecular iris angle (TIA) were measured.

RESULTS

Pupil diameter was similar between the AM and PM groups in the light (P=0.89) and dark (P=0.51). There was no significant difference between AM and PM measurement values for any of the static or dynamic parameters in the light (P>0.39) and dark (P>0.31). Intraclass correlation coefficients (ICC) demonstrated excellent agreement between AM and PM measurement values in the light (ICC>0.81) and dark (ICC>0.93). In addition, there was no significant difference between AM and PM angle opening distance at 500 µm measurement values in the light (P>0.34) and dark (P>0.40) when each of 8 angle sectors was analyzed individually.

CONCLUSIONS

No significant diurnal variation of static or dynamic anterior segment parameter measurements was detected in the light and dark. Diurnal variation of these parameters does not regularly occur in young, healthy eyes.

Ocular Biometric Characteristics of Chinese with History of Acute Angle Closure

PURPOSE

To investigate the biometric characteristics of Chinese patients with a history of acute angle closure (AAC).

METHODS

In this clinic-based, retrospective, observational, cross-sectional study, biometric parameters of eyes were acquired from a general population of Chinese adults. The crowding value (defined as lens thickness (LT); central corneal thickness (CCT); anterior chamber depth (ACD)/axial length (AL)) was calculated for each patient. Logistic regression analysis was performed to identify risk factors for AAC. Receiver operating characteristic (ROC) curves were plotted, and biometric variables were compared to compile a risk assessment for AAC.

RESULT

This study included 1500 healthy subjects (2624 eyes, mean age of 66.54 ± 15.82 years) and 107 subjects with AAC (202 eyes, mean age of 70.01 ± 11.05 years). Eyes with AAC had thicker lens (P ≤ 0.001), shallower anterior chamber depth (P ≤ 0.001), and shorter axial length (P ≤ 0.001) than healthy eyes. Logistic regression analysis and ROC curve analysis indicated that a crowding value above 0.13 was a significant (P < 0.05) risk factor for the development of AAC.

CONCLUSIONS

Biometric parameters were significantly different between the eyes from the AAC group to the normal group. Ocular crowding value might be a new noncontact screening method to assess the risk of AAC in adults.

Differences between fellow eyes of acute and chronic primary angle closure (glaucoma): An ultrasound biomicroscopy quantitative study

PURPOSE

To compare various biometric parameters between fellow eyes of acute primary angle closure (glaucoma) [APAC(G)] and fellow eyes of chronic primary angle closure (glaucoma) [CPAC(G)].

METHODS

Ultrasound biomicroscopy examinations were performed on 47 patients with unilateral APAC(G) and 41 patients with asymmetric CPAC(G) before laser peripheral iridotomy and pilocarpine treatment. Anterior chamber depth and width (ACD and ACW), lens vault (LV), iris curvature (IC), iris root distance (IRD), trabecular-ciliary process distance (TCPD), iris-ciliary process distance (ICPD), trabecular-ciliary angle (TCA), and other biometric parameters were compared between fellow eyes of APAC(G) and fellow eyes of CAPC(G).

RESULTS

Compared with fellow eyes of CPAC(G), fellow eyes of APAC(G) had smaller ACD (P < 0.001), ACW (P = 0.007), TCPD (P = 0.016), ICPD (P = 0.008), and TCA (P = 0.006), as well as larger LV (P = 0.002), IC (P = 0.012), and IRD (P = 0.003). On multivariate logistic regression analyses, a 0.1 mm decrease in ACD (odds ratio [OR]: 0.705, 95%CI: 0.564-0.880, P = 0.002), ICPD (OR: 0.557, 95%CI: 0.335-0.925, P = 0.024), and a 0.1 mm increase in IRD (OR: 2.707, 95%CI: 1.025-7.149, P = 0.045), was significantly associated with occurrence of acute angle closures.

CONCLUSIONS

Fellow eyes of APAC(G) had smaller anterior segment dimensions, higher LV, more posterior iris insertion, greater IC, and more anteriorly rotated ciliary body compared with fellow eyes of CPAC(G). ACD, ICPD, and IRD were the three most important parameters that distinguish eyes predisposed to APAC(G) or CPAC(G).

Narrowing of the Anterior Chamber Angle during Valsalva Maneuver: A Possible Mechanism for Angle Closure

Purpose

To evaluate changes at the anterior chamber angle during Valsalva maneuver in eyes suspected to have a primary adult glaucoma.

Methods

Seventy-six consecutive patients underwent recording of applanation tonometry, measurement of the anterior chamber angle recess, angle opening distance, angle recess area, scleral spur-iris root distance, iris thickness, iridociliary angle, ciliary body thickness, anterior chamber depth, and pupil size on ultrasound biomicroscopy before and during the Valsalva maneuver. The Valsalva maneuver was standardized to a pressure of 40 mmHg for 15 seconds, using a manometer.

Results

The mean baseline intraocular pressure changed from 19.5±4.1 mmHg to 29.5±4.8 mmHg during Valsalva (p<0.0001). The anterior chamber angle recess narrowed from 17.9±9.5 to 7.8±9.2 degrees (p=0.0001). The angle recess area diminished from 0.15±0.14 mm2 to 0.14±0.12 mm2 (p=0.03) and the scleral spur to iris distance decreased from 0.19±0.2 mm to 0.16±0.18 mm (p=0.0001). The iridociliary angle narrowed from 72.6±33.5 degrees to 62.5±32.8 degrees (p=0.04). There was a significant increase in the thickness of the ciliary body, from 0.99±0.19 mm to 1.12±0.16 mm (p=0.001) and in iris thickness from 0.47±0.07 mm to 0.55±0.09 mm (p=0.0001). There was no significant change in the angle opening distance, anterior chamber depth, or pupillary diameter. A significant narrowing of the angle to less than 5 degrees was seen in 37 eyes, with iridocorneal apposition present in 28 eyes. After multivariate regression analysis it was found that the baseline ciliary body thickness and angle recess were significant predictors of narrowing of the angle (R2=96.1%).

Conclusions

Significant elevation of the intraocular pressure, narrowing of the anterior chamber angle recess, thickening of the ciliary body, and increase in the iris thickness is seen during the Valsalva maneuver. The Valsalva maneuver may lead to angle closure in eyes anatomically predisposed to primary angle closure glaucoma.

Measurement of and Factors Associated with the Anterior Chamber Volume in Healthy Chinese Adults

Purpose. To measure the anterior chamber volume (ACV) and determine factors associated with the ACV in healthy Chinese adults. Methods. In this cross-sectional study, we used swept-source optical coherence tomography (SS-OCT) to measure ACV and other anterior segment parameters. Factors associated with ACV were also determined. Results. A total of 313 healthy Chinese adults were enrolled. The anterior segment parameters, including ACV, could be measured by SS-OCT with excellent repeatability and reproducibility. There was a significant difference between the horizontal and vertical anterior chamber widths (ACW) (P < 0.05), with a mean difference of 390 μm. The ACV (mean 153.83 ± 32.42 mm³) was correlated with most of the anterior segment parameters, especially anterior chamber depth (ACD), which accounted for about 85% of the variation of ACV. Most of the anterior segment parameters were significantly correlated with age, and the relative changes in ACV and ACD were greatest in subjects aged 41–50 years. Conclusion. ACV was correlated with most of the anterior segment parameters measured in this study, particularly ACD. The relatively large difference between horizontal and vertical ACW suggests that the ACV could and should be measured using multiple OCT scans.

Applications of Scheimpflug Imaging in Glaucoma Management: Current and Potential Applications

Scheimpflug photography is the basis for a variety of imaging devices that are highly versatile. The applications of Scheimpflug imaging are wide in scope, spanning from evaluation of corneal ectasia to quantifying density in nuclear sclerotic cataracts. The potential uses for Scheimpflug-based devices are expanding and a number of them are relevant in glaucoma. In particular, they can provide three-dimensional image reconstruction of the anterior segment which includes assessment of the iridocorneal angle. Photographic analyses allow also for a noncontact method of estimating central corneal thickness (CCT) and intraocular pressure (IOP), as well as the study of various corneal biomechanical properties, which may be useful for stratifying glaucoma risk.

Iris Crypts Influence Dynamic Changes of Iris Volume

PURPOSE

To determine the association of iris surface features with iris volume change after physiologic pupil dilation in adults.

DESIGN

Cross-sectional observational study.

PARTICIPANTS

Chinese adults aged ≥ 50 years without ocular diseases.

METHODS

Digital iris photographs were taken from eyes of each participant and graded for crypts (by number and size) and furrows (by number and circumferential extent) following a standardized grading scheme. Iris color was measured objectively, using the Commission Internationale de l'Eclairage (CIE) L* color parameter (higher value denoting lighter iris). The anterior segment was imaged by swept-source optical coherence tomography (SS-OCT) (Casia; Tomey, Nagoya, Japan) under bright light and dark room conditions. Iris volumes in light and dark conditions were measured with custom semiautomated software, and the change in iris volume was quantified. Associations of the change in iris volume after pupil dilation with underlying iris surface features in right eyes were assessed using linear regression analysis.

MAIN OUTCOME MEASURES

Iris volume change after physiologic pupil dilation from light to dark condition.

RESULTS

A total of 65 Chinese participants (mean age, 59.8±5.7 years) had gradable data for iris surface features. In light condition, higher iris crypt grade was associated independently with smaller iris volume (β [change in iris volume in millimeters per crypt grade increment] = -1.43, 95% confidence interval [CI], -2.26 to -0.59; P = 0.001) and greater reduction of iris volume on pupil dilation (β [change in iris volume in millimeters per crypt grade increment] = 0.23, 95% CI, 0.06-0.40; P = 0.010), adjusting for age, gender, presence of corneal arcus, and change in pupil size. Iris furrows and iris color were not associated with iris volume in light condition or change in iris volume (all P > 0.05).

CONCLUSIONS

Although few Chinese persons have multiple crypts on their irides, irides with more crypts were significantly thinner and lost more volume on pupil dilation. In view that the latter feature is known to be protective for acute angle-closure attack, it is likely that the macroscopic and microscopic composition of the iris is a contributing feature to angle-closure disease.

Qualitative evaluation of anterior segment in angle closure disease using anterior segment optical coherence tomography

PURPOSE

To evaluate different mechanisms of primary angle closure (PAC) and to quantify anterior chamber (AC) parameters in different subtypes of angle closure disease using anterior segment optical coherence tomography (AS-OCT).

METHODS

In this prospective study, 115 eyes of 115 patients with angle closure disease were included and categorized into three groups: 1) fellow eyes of acute angle closure (AAC; 40 eyes); 2) primary angle closure glaucoma (PACG; 39 eyes); and 3) primary angle closure suspect (PACS; 36 eyes). Complete ophthalmic examination including gonioscopy, A-scan biometry, and AS-OCT were performed. Based on the AS-OCT images, 4 mechanisms of PAC including pupillary block, plateau iris configuration, thick peripheral iris roll (PIR), and exaggerated lens vault were evaluated. Angle, AC, and lens parameter variables were also evaluated among the three subtypes.

RESULTS

There was a statistically significant difference in the mechanism of angle closure among the three groups (p = 0.03). While the majority of fellow eyes of AAC and of PACS eyes had pupillary block mechanism (77.5% and 75%, respectively), only 48.7% of PACG eyes had dominant pupillary block mechanism (p = 0.03). The percentage of exaggerated lens vault and plateau iris mechanisms was higher in PACG eyes (25.5% and 15.4%, respectively). Fellow eyes of AAC had the shallowest AC (p = 0.01), greater iris curvature (p = 0.01), and lens vault (p = 0.02) than PACS and PACG eyes. Iris thickness was not significantly different among the three groups (p = 0.45).

CONCLUSION

Using AS-OCT, we found that there was a statistically significant difference in the underlying PAC mechanisms and quantitative AC parameters among the three subtypes of angle closure disease.

Laser peripheral iridotomy changes anterior chamber architecture

PURPOSE

The pressure gradient between anterior and posterior chamber in acute angle closure (AAC) and primary angle closure suspects is balanced by a sufficient laser peripheral iridotomy (LPI). The anterior chamber changes induced by LPI in patients with unilateral AAC were examined and compared to healthy eyes to define threshold values, which may help to discriminate between healthy and diseased eyes.

METHODS

Using Scheimpflug photography, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured before and after LPI in both eyes of unilateral AAC cases. These measurements were compared to a group of healthy control eyes to determine threshold values for ACD, ACV, and ACA.

RESULTS

The ACD, ACV, and ACA increased significantly in the 25 AAC eyes after LPI. The ACD, ACV, ACA, and CCT values in the AAC eyes obtained before LPI were compared to a control group of 59 healthy eyes with wide open chamber angles. The cutoff values revealed by receiver operating characteristic analysis were 2.1 mm for ACD, 90.5 mm2 for ACV, and 27.25° for ACA.

CONCLUSIONS

Our results confirm the significant changes of the anterior segments architecture induced by LPI in AAC eyes. The found threshold values for ACD, ACV, and ACA may help in daily clinical routine to discriminate between healthy eyes and those in need for a prophylactic LPI.

The anterior chamber depth and retinal nerve fiber layer thickness in children

Purpose. To investigate the correlation of anterior chamber depth (ACD) with the peripapillary retinal nerve fiber layer (RNFL) thickness, age, axial length (AL), and spherical equivalent in children. Subjects. Consecutive subjects aged 4 to 18 were recruited. Visually disabling eye conditions were excluded. Only the right eye was included for analysis. The ACD was correlated with RNFL thickness, age, spherical equivalent, and AL for all subjects. Subjects were then divided into 3 groups based on their postcycloplegic spherical equivalent: myopes (<−1.0 D), emmetropes (≥−1.0 to ≤+1.0 D), and hyperopes (>+1.0 D). The ACD was compared among the 3 groups before and after age adjustment. Results. In 200 subjects (mean age 7.6 ± 3.3 years), a deeper ACD was correlated with thinner global RNFL (r = −0.2, r² = 0.06, P = 0.0007), older age (r = 0.4, r² = 0.1, P < 0.0001), myopic spherical equivalent (r = −0.3, r² = 0.09, P < 0.0001), and longer AL (r = 0.5, r² = 0.2, P < 0.0001). The ACD was deepest in myopes (3.5 ± 0.4 mm, n = 67), followed by emmetropes (3.4 ± 0.3, n = 60) and then hyperopes (3.3 ± 0.2, n = 73) (all P < 0.0001). After age adjustment, myopes had a deeper ACD than the other 2 groups (all P < 0.0001). Conclusions. In children, a deeper ACD was associated with thinner RNFL thickness, older age, more myopic spherical equivalent, and longer AL. Myopes had a deeper ACD than emmetropes and hyperopes.

Associations between narrow angle and adult anthropometry: the Liwan Eye Study

PURPOSE

To assess the associations between narrow angle and adult anthropometry.

METHODS

Chinese adults aged 50 years and older were recruited from a population-based survey in the Liwan District of Guangzhou, China. Narrow angle was defined as the posterior trabecular meshwork not visible under static gonioscopy in at least three quadrants (i.e. a circumference of at least 270°). Logistic regression models were used to examine the associations between narrow angle and anthropomorphic measures (height, weight and body mass index, BMI).

RESULTS

Among the 912 participants, lower weight, shorter height, and lower BMI were significantly associated with narrower angle width (tests for trend: mean angle width in degrees vs weight p < 0.001; vs height p < 0.001; vs BMI p = 0.012). In univariate analyses, shorter height, lower weight and lower BMI were all significantly associated with greater odds of narrow angle. The crude association between height and narrow angle was largely attributable to a stronger association with age and sex. Lower BMI and weight remained significantly associated with narrow angle after adjustment for height, age, sex, axial ocular biometric measures and education. In analyses stratified by sex, the association between BMI and narrow angle was only observed in women.

CONCLUSION

Lower BMI and weight were associated with significantly greater odds of narrow angle after adjusting for age, education, axial ocular biometric measures and height. The odds of narrow angle increased 7% per 1 unit decrease in BMI. This association was most evident in women.

Role of lens vault in subtypes of angle closure in Iranian subjects

PURPOSE

The purpose of this study is to quantify anterior chamber (AC) parameters and to determine the proportion of eyes with exaggerated lens vault (LV) in different subtypes of angle closure disease using anterior segment optical coherence tomography (AS-OCT).

PATIENTS AND METHODS

In this prospective study, 115 eyes of 115 Iranian patients with angle closure disease were included and categorized into three groups: (1) fellow eyes of acute angle closure (AAC; 40 eyes); (2) primary angle closure glaucoma (PACG; 39 eyes); and (3) primary angle closure suspect (PACS; 36 eyes). Complete ophthalmic examination including gonioscopy, A-scan biometry, and AS-OCT were performed. Angle parameters, LV, and iris thickness (IT) were measured using AS-OCT. An exaggerated LV was defined as LV more than one-third the distance between the corneal endothelium and a line drawn to connect the nasal and temporal scleral spurs.

RESULTS

Fellow eyes of AAC had the shallower AC (P=0.01), greater iris curvature (I-curve; P=0.01), and higher LV (P=0.02) as compared with PACS and PACG eyes. There was no statistically significant difference in the mean IT at 750 μm from scleral spur among the three groups (P=0.45). Exaggerated LV was found in 67.5, 35.9, and 40% of fellow eyes of AAC, PACG, and PACS, respectively, (P=0.008) with an odds ratio of 1.92 (P=0.005) for fellow vs PACG and 1.68 (P=0.01) for fellow vs PACS.

CONCLUSIONS

Exaggerated LV is highly prevalent in fellow eyes of AAC. These eyes have shallower AC depth, greater I-curve, and higher LV when compared with PACG and PACS.

Assessment of the anterior chamber parameters after laser iridotomy in primary angle close suspect using Pentacam and gonioscopy

AIM

To evaluate the changes in the anterior segment parameters of the subjects with primary angle closure suspect (PACS) before and after laser iridotomy (LI) using the Pentacam and gonioscopy.

METHODS

Forty-eight eyes of 48 PACS were included. Anterior chamber angle (ACA), central anterior chamber depth (ACD), anterior chamber volume (ACV) and central corneal thickness (CCT) were recorded from the Pentacam before and one month after LI. ACA was graded according to Shaffer classification using the Goldmann gonioscopy.

RESULTS

ACA increased significantly from 25.59±4.41 to 26.46±4.33 degrees (P=0.009) and ACV changed from 85.97±16.07mm(3) to 99.25±15.83mm(3) (P=0.000). The changes in ACD, CCT and intraocular pressure were non-significant (P>0.05). Gonioscopy showed significant widening of the Shaffer angle in 4 quadrants (P<0.001).

CONCLUSION

Pentacam can serve as the objective instrument in assessing the efficacy of LI.

The biometric study in different stages of primary angle-closure glaucoma

PURPOSE

This study compared the general and ocular biometric characteristics of normal, primary angle closure (PAC), and primary angle-closure glaucoma (PACG) patients to better understand the possible relationship between differences in ocular parameters that might predict risk for PACG in PAC patients.

METHODS

One hundred normal, 90 PAC, and 90 PACG eyes were retrospectively reviewed. General characteristics such as age, gender, body height, body weight, blood pressure, pulse, systemic diseases, and education level were recorded. Ocular findings included visual acuity, intraocular pressure, refraction, cup to disc ratio, and ocular biometry. Ocular biometry was obtained by A-scan ultrasonography (Digital A/B scan 5500; Sonomed Inc., Lake Success, NY, USA). The parameters recorded were anterior chamber depth (ACD), lens thickness (LT), axial length (AXL), lens/axial length factor (LAF), and relative lens position (RLP).

RESULTS

Although the controls, PAC group, and PACG group were found to be significantly different in age (62.7±9.8; 65.3±7.5; and 66.0±7.4, respectively), there were no gender differences. With regard to ocular parameters, the ACD tended to decrease and the LT and LAF tended to increase from normal to PAC to PACG. The eyes of the PACG group had significantly shallower ACD (P<0.001) and thicker lens (P<0.001) than those of the PAC group. While PAC had similar lens position to the control group, PACG had more anteriorly positioned lens than the PAC group (P<0.001). Logistic regression analysis found a significant association between a decrease in ACD and increased risk of PACG (odds ratio (OR)=3.59 for 0.2 mm decrease in ACD) as well as a significant association between an increase in LT and increased risk of PACG (OR=1.30).

CONCLUSIONS

In addition to LT, a shallower ACD owing to a change in RLP may have a role in the progression from PAC to PACG. Owing to the differences of certain biometric characteristics between PAC and PACG, A-scan ultrasonography might potentially be used for the early detection of PACG in PAC eyes.

Anterior segment imaging in glaucoma

Anterior segment imaging allows objective assessment of the anterior segment of the eye, particularly the anterior chamber angle. Both qualitative and quantitative analyses are possible and aid in detecting and managing closed-angle and open-angle mechanisms in various forms of glaucoma. This review focuses primarily on anterior segment optical coherence tomography and ultrasound biomicroscopy, with emphasis on principles of technology, commercially available devices, and clinical applications in glaucoma with potential advantages and disadvantages of each technology.

Ocular biometry in the subtypes of angle closure: an anterior segment optical coherence tomography study

PURPOSE

To evaluate ocular biometric parameters in different subtypes of angle-closure disease in the Iranian population and compare them with normal eyes.

DESIGN

Prospective, cross-sectional.

METHODS

In this clinic-based study, 189 eyes of 154 patients consisting of 40 acute angle-closure glaucoma (AACG) eyes, 40 fellow eyes of AACG, 42 chronic angle-closure glaucoma (CACG) eyes, 40 primary angle-closure suspect (PACS) eyes, and 27 normal eyes underwent complete examination including gonioscopy, A-scan biometry, and anterior segment optical coherence tomography. Only 1 eye of CACG, PACS, and control subjects were selected. Main outcome measures included angle opening distance and trabeculo-iris space area at 500 μm from the scleral spur (AOD500, TISA-500), anterior chamber angle, lens vault, lens thickness, anterior chamber depth (ACD), and lens position.

RESULTS

Anterior chamber angle, AOD500, TISA500, ACD, and lens position were less and lens thickness and lens vault were greater in angle-closure than open-angle eyes. ACD was less in AACG than CACG and PACS (P < .001). It was also less in fellow eyes than PACS eyes (P = .04). Lens vault was highest in AACG eyes, followed by fellow eyes, PACS, and CACG. It was significantly more in AACG eyes than CACG and PACS eyes (P < .001 and P = .007, respectively). No difference was observed between AACG and fellow eyes.

CONCLUSIONS

The anterior segment was crowded in closed-angle compared to open-angle eyes. Higher lens vault may play a role in the development of an acute attack of angle closure.

Power prediction for one-piece and three-piece intraocular lens implantation after cataract surgery in patients with chronic angle-closure glaucoma: a prospective, randomized clinical trial

PURPOSE

To assess the accuracy of intraocular lens (IOL) power prediction for cataract surgery in chronic angle-closure glaucoma (CACG) patients with different IOLs' implantation.

METHODS

This prospective randomized clinical trial included 45 eyes with CACG and 48 eyes with normal controls undergoing cataract surgery. In the CACG group, 23 eyes (51%) had three-piece IOL implantation and 22 eyes (49%) had one-piece IOL implantation. In the normal control group, 25 eyes (52%) had three-piece IOL implantation and 23 eyes (48%) had one-piece IOL implantation. Using the SRK/T formula, the mean difference between the predicted and actual postoperative spherical equivalent [mean absolute error (MAE)] was obtained and converted to natural logarithm (ln) for statistical analysis. The power of the implanted IOL was calculated to predict postoperative SE using three formulas: SRK II, Holladay II and Hoffer Q by post hoc analysis in each group. The predictive accuracy of each formula was analysed by comparing the lnMAE.

RESULTS

In the one-piece IOL group, there was no difference in lnMAE between the CACG and normal control group (p = 0.314). In the three-piece IOL group, the lnMAE of the CACG group was larger than that of the normal control group (p < 0.001). The lnMAEs calculated by the SRK/T formula were more accurate than the Holladay II (p = 0.045) and Hoffer Q (p = 0.042) formula in the CACG one-piece IOL group.

CONCLUSIONS

Implantation of one-piece IOLs provides similar power prediction accuracy comparable to normal cataract patients; this result may be explained by the IOL haptic configuration or design.

Effects of phacoemulsification on intraocular pressure and anterior chamber depth

The aim of this study was to investigate the effects of phacoemulsification with intraocular lens (IOL) implantation on intraocular pressure (IOP) and anterior chamber depth (ACD) in patients with cataract or cataract associated with primary angle closure (PAC). A total of 361 patients (481 affected eyes) with senile cataract (cataract group) and 44 patients (52 affected eyes) with cataract associated with PAC (cataract with PAC group) underwent phacoemulsification with IOL implantation from July 2005 to May 2007 and were followed up for 3 to 25 months. There was a significant difference between pre-operative and post-operative IOPs (t=9.270, P<0.01) in the cataract group and in the cataract with PAC group (t=3.29, P<0.01). No significant differences were identified in pre-operative IOP (t=-2.437, P>0.05) and the IOP three months after surgery (t=2.154, P>0.05) between the two groups. There was a significant difference between the pre-operative and post-operative ACDs (t=7.781, P<0.01) in the cataract group and in the cataract with PAC group (t=4.528, P<0.01). A significant difference in ACD between the two groups (t=8.325, P<0.01) existed prior to surgery but following surgery, the ACDs of the two groups were not significantly different (t=2.86, P>0.05). Phacoemulsification with IOL implantation has IOP-lowering effects on cataract and cataract with PAC patients. The International Society of Geography and Epidemiology of Ophthalmology classification method for angle closure glaucoma was adopted in our study. Furhter studies are required to prove the safety and mechanism of lowering IOP impact of phacoemulsifation towards PAC glaucoma (PACG).

Dark-light change of iris parameters and related factors among American Caucasians, American Chinese, and Mainland Chinese

PURPOSE

To assess the distribution of dark-light changes in iris features and associated factors amongst American Caucasians, American Chinese and mainland Chinese aged 40 years and over.

METHODS

Four gender- and age-matched cohorts: Caucasians, American Chinese, Southern Chinese and Northern Chinese comprised the study population. Anterior segment optical coherence tomography (ASOCT) images were acquired under dark and light conditions. Customized software was used to calculate iris thickness at 750 μm from the scleral spur (IT750), iris curvature (ICurv), iris area (IArea), and pupil diameter (PD) from ASOCT images.

RESULTS

Data from 121, 124, 121 and 120 subjects were available for American Caucasian, American Chinese, Southern and Northern Chinese subjects respectively. Caucasians had significantly less dark-light change (Δ) of IT750 and greater ΔPD than Chinese. When using multiple linear regression analyses, the inter-ethnic difference for ΔIT750 was independent of age, gender, refractive error, anterior chamber width and axial length. After controlling for ΔPD, ΔICurv was found to be inversely associated with age (β = -0.001, P = 0.001). Independent predictors of greater ΔPD included younger age (β = -0.02, P = 0.001), Caucasian ethnicity (β = -0.022, P = 0.009) and wider anterior chamber (β = 0.18, P = 0.03).

CONCLUSIONS

Compared with Caucasians, Chinese irides show greater thickening with light to dark adaptation despite the lesser change of PD in Chinese. The change of iris area per unit change of pupil diameter from dark to light did not differ between ethnicities. These dynamic characteristics intrinsic to Chinese irides may partially account for the substantially increased risk for angle closure among this ethnic group.