Anterior Segment Characteristics and Risk Factors for Primary Angle Closure Disease With Long Axial Lengths: The Handan Eye Study.

Purpose: To investigate the anterior segment characteristics of primary angle closure disease (PACD) with long axial length (AL) compared with that of those with short and medium AL and explore the risk factors associated with AC with different AL levels. Methods: This observational cross-sectional study enrolled subjects aged 35 years or older who completed the follow-up examinations of the Handan Eye Study and dichotomized them into normal and PACD groups. Ocular data of the right eye were analyzed. AL was categorized into short (<22.0 mm), medium (22.0-24.0 mm), or long (>24.0 mm) subgroups. Demographic and anterior segment parameters of PACD subjects were compared between the three AL subgroups. Logistic regression analysis was performed to identify the risk factors for PACD in the three subgroups. Results: Data from 715 PACD and 1446 normal subjects were analyzed. Only 6.6% of the PACD eyes had long AL, with lower spherical equivalent, larger anterior chamber depth (P < 0.001), and smaller lens thickness (P < 0.001) than those with short and medium AL. No significant differences were found for angle opening distance and iris parameters on comparing the values of eyes with long AL with that of those with short and medium AL. Significant risk factors for the development of PACD with long AL were peripheral iris thickness, anterior chamber width, and lens vault. Conclusions: PACD with long AL was uncommon. A thicker peripheral iris, larger lens vault, and smaller ACW contributed to angle closure in these patients.

Predictors of angle widening after laser iridotomy in Chinese patients with primary angle-closure suspect using ultrasound biomicroscopy.

AIM: To assess the predictive value of baseline parameters of ultrasound biomicroscopy (UBM) for angle widening after prophylactic laser peripheral iridotomy (LPI) in patients with primary angle-closure suspect (PACS). METHODS: Angle-opening distance (AOD), trabecular iris angle (TIA), iris thickness, trabecular-ciliary process angle, and trabecular-ciliary process distance were measured using UBM performed before and two weeks after LPI. Iris convexity (IC), iris insertion, angulation, and ciliary body (CB) size and position were graded. Uni- and multivariate regression analyses were used to determine factors predicting the change in AOD (ΔAOD500, calculated as an angle width change before and after LPI) in all quadrants and in subgroup quadrants based on IC. RESULTS: In 94 eyes of 94 patients with PACS, LPI led to angle widening with increases in AOD500 and TIA (P<0.01). Multivariable regression analysis showed that IC (P<0.001), CB position (P=0.007) and iris insertion (P=0.049) were significantly predictive for ΔAOD500. All quadrants were categorized into extreme IC (27.8%), moderate IC (62.3%), and absent IC (9.9%) subgroups. The AOD500 increased by 220% and no other predictive factor was found in the extreme IC quadrants. The AOD500 increased by 55%, and baseline iris angulation was predictive for smaller changes in ΔAOD500 in the moderate IC quadrants. CONCLUSION: In PACS patients, quadrants with greater iris bowing predict substantial angle widening after LPI. Quadrants with a flatter iris, anteriorly positioned CB, and basal iris insertion are associated with less angle widening after LPI. Quadrants with iris angulation as well as a flatter iris configuration predict a smaller angle change after LPI.

Longitudinal observation of intraocular pressure variations with acute altitude changes.

BACKGROUND: Higher intraocular pressure (IOP) is a major risk factor for developing glaucoma, and the leading cause of irreversible blindness worldwide. High altitude (HA) may be involved in IOP, but the reported results were conflicting. Ascent to HA directly by plane from low altitude regions is an acute, effortless exposure. However, the effects of such exposure to different altitudes on IOP have rarely been reported. AIM: To investigate changes in IOP after rapid effortless exposure to HA in stages and compare it with systemic parameters. METHODS: Fifty-eight healthy subjects (116 eyes) were divided into three groups: 17 low-altitude (LA) residents [44 m above sea level (ASL)], 22 HA residents (2261 m ASL) and 19 very HA (VHA) residents (3750 m ASL). The LA group flew to HA first. Three days later, they flew with the HA group to VHA where both groups stayed for 2 d. Then, the LA group flew back to HA and stayed for 1 d before flying back to 44 m. IOP, oxygen saturation (SpO2) and pulse rate were measured. The linear mixed model was used to compare repeated measurements. RESULTS: IOP in the LA group significantly decreased from 18.41 ± 2.40 mmHg at 44 m to 13.60 ± 3.68 mmHg at 2261 m ASL (P < 0.001), and then to 11.85 ± 2.48 mmHg at 3750 m ASL (P = 0.036 compared to IOP at 2261 m ASL) and partially recovered to 13.47 ± 2.57 mmHg upon return to 44 m. IOP in the LA group at HA and VHA was comparable to that in the local residents (12.2 ± 2.4 mmHg for HA,11.5 ± 1.8 mmHg for VHA). IOP was positively associated with SpO2. CONCLUSION: IOP in the LA group gradually reduced as altitude elevated in stages and became comparable to IOP in local residents. Hypoxia may be associated with IOP, which deserves further study.

Intervention of laser periphery iridectomy to posterior iris bowing in high myopic eyes.

BACKGROUND: For some high myopic patients with posterior iris bowing, laser periphery iridectomy should be performed pre-operation to prevent pupil block glaucoma if these patients would have phakic intraocular lens implantation to correct high myopia. So we had the opportunity to analysis the influence of laser iridectomy on posterior iris bowing. METHODS: Eighteen high myopic patients with posterior iris bowing (11 males and 7 females) were involved in the study in Beijing Tongren Eye Center from March 2008 to July 2008. Phakic intraocular lens were implanted to correct their ametropia. The mean age was (32 ± 6) years (range, 25 - 40 years). The center anterior chamber depth, the pupil diameter, the posterior iris bowing depth and the anterior chamber angle were measured with anterior segment coherence tomography (AS-OCT) under the normal condition, myosis condition induced by 2% pilocarpine, laser periphery iridectomy after myosis, and 2% pilocarpine eluting condition respectively. RESULTS: There was no significant difference of center anterior chamber depth under the four conditions (P = 0.512). The pupil constricted after pilocarpine (P = 0.001). After laser iridectomy performed and pilocarpine eluted, posterior iris bowing depth reduced more than that in normal condition (P = 0.003). The anterior chamber angle reduced significantly after laser periphery iridectomy and pilocarpine eluted (P = 0.012). CONCLUSION: Laser periphery iridectomy can reduce the posterior iris bowing, which might be due to the change in aqueous circulate pathway.

Comparative study of optic disc measurement by Copernicus optical coherence tomography and Heidelberg retinal tomography.

BACKGROUND: Copernicus optical coherence tomography (SOCT) is a new, ultra high-speed and high-resolution instrument available for clinical evaluation of optic nerve. The purpose of the study was to compare the agreements between SOCT and Heidelberg retinal tomography (HRT). METHODS: A total of 44 healthy normal volunteers were recruited in this study. One eye in each subject was selected randomly. Agreement between SOCT and HRT-3 in measuring optic disc area was assessed using Bland-Altman plots. Relationships between measurements of optic nerve head parameter obtained by SOCT and HRT-3 were assessed by Pearson correlation. RESULTS: There was no significant difference in the average cup area (0.306 vs. 0.355 mm, P = 0.766), cup volume (0.158 vs. 0.130 mm, P = 0.106) and cup/disc ration (0.394 vs. 0.349 mm, P = 0.576) measured by the two instruments. However, other optic disc parameters from SOCT were significantly lower compared with HRT-3. The Bland-Altman plot revealed good agreement of cup area and cup volume measured by SOCT and HRT-3. Bad agreement of disc area, rim area, rim volume and cup/disc ratio were found between SOCT and HRT-3. The highest correlations between the two instruments were observed for cup area (r(2) = 0.783, P = 0.000) and cup/disc ratio (r(2) = 0.669, P = 0.000), whereas the lowest correlation was observed for disc area (r(2) = 0.100, P = 0.037), rim area (r(2) = 0.275, P = 0.000), cup volume (r(2) = 0.005, P = 0.391) and rim volume (r(2) = 0.021, P = 0.346). CONCLUSIONS: There were poor agreements between SOCT and HRT-3 for measurement of optic nerve parameters except cup area and cup volume. Measurement results of the two instruments are not interchangeable.

[Significance of optic disc topography and retinal nerve fiber layer thickness measurement by spectral-domain OCT in diagnosis of glaucoma].

OBJECTIVE: To study the significance of optic disc tomography and retinal nerve fiber layer (RNFL) thickness measurement by spectral-domain optical coherence tomography (OCT) in the diagnosis of glaucoma. METHODS: It was a noninterventional, observational study. The optic disc topographic parameters and total and regional RNFL thickness were measured by RTVue OCT in 60 normal eyes and 97 glaucomatous eyes. One-way analysis of variance was used to compare the parameters above mentioned between normal and glaucomatous groups. The area under the receiver operating characteristic curve (AUC) and the sensitivity at 80% specificity were used to assess the ability of each testing parameter in the differentiation between normal and glaucoma eyes. RESULTS: There were statistically significant differences in all RTVue OCT measurement parameters (F = 1.024, P = 0.596;F = 36.519, 54.464, 27.659, 36.176, 20.562, 63.833, 30.031, 54.652, 98.146, 78.705, 99.839, 43.728, 75.720, 45.709, 39.380, 33.590, 66.887, 78.335, 45.485;P = 0.000) except disc area. The average RNFL thickness in normal, early, moderate and advanced glaucomatous eyes was 109.950, 93.313, 80.374 and 65.570 µm, respectively. Among the eight regions around the optic disc, the thickest RNFL was located at the inferotemporal (150.066 µm) and superotemporal (146.285 µm) regions in normal eyes, and the superotemporal (108.569, 103.420 and 88.708 µm in early, moderate and advanced glaucomatous eyes, respectively) and inferotemporal (108.201, 102.830 and 86.369 µm in early, moderate and advanced glaucomatous eyes, respectively) regions in glaucomatous eyes. Both in normal and glaucomatous eyes, the thinnest RNFL was located at the nasal and temporal regions, respectively. For optic disc topographic parameters, the highest AUC was vertical cup/disc ratio (AUC = 0.762, 0.946 and 0.988 in early, moderate and advanced glaucomatous eyes, respectively), and the sensitivity at 80% specificity was 62.2%, 76.5% and 99.2% in early, moderate and advanced glaucomatous eyes, respectively. For RNFL thickness, the highest AUC was superotemporal region RNFL thickness (AUC = 0.915) and the sensitivity at 80% specificity was 89.5% in early glaucomatous eyes. The highest AUC was inferior average RNFL thickness (AUC = 0.967) and the sensitivity at 80% specificity was 94.1% in moderate glaucomatous eyes. The highest AUC was average RNFL thickness (AUC = 0.985) and the sensitivity at 80% specificity was 99.2% in advanced glaucomatous eyes. Among the eight regions around the optic disc, RNFL thickness of region ST (AUC = 0.915, 0.926 and 0.966 in early, moderate and advanced glaucomatous eyes, respectively) achieved the highest AUC. RNFL thicknesses of the nasal and temporal regions showed the lowest AUCs. CONCLUSIONS: RTVue OCT shows fair discriminating ability in distinguishing normal from glaucomatous eyes. RTVue OCT is a useful equipment for the diagnosis of glaucoma.

Reproducibility of RTVue retinal nerve fiber layer thickness and optic nerve head measurements in normal and glaucoma eyes.

BACKGROUND: RTVue spectral-domain optical coherence tomography (OCT) is a new, ultra high-speed and high-resolution instrument, potentially to measure the presence of glaucoma or its progression accurately. The objective of this study was to evaluate its reproducibility of retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) measurements in normal and glaucoma eyes. METHODS: This study was an observational clinical study. One eye was selected randomly from each of 89 normal individuals and 63 glaucoma patients in a range of severity. RNFL thickness and ONH were measured 3 times on the same day to determine intrasession variability. The same instrument was used by the same operator for all scans. Intrasession within-subject standard deviation (Sw), precision (1.96 x Sw), coefficient of variation (CVw, 100 x Sw/overall mean), and intraclass coefficient (ICC) were calculated to evaluate reproducibility. RESULTS: RTVue OCT demonstrated double hump patterns in the RNFL profiles. High reproducibility was observed in all ONH parameters. For normal eyes, the value of ICC ranged between 0.98 and 1.00. For eyes with different extent of glaucoma, it ranged between 0.94 and 1.00. High reproducibility was also observed in RNFL thickness measurements. The values of ICC for averaged RNFL thickness ranged between 0.95 and 1.00 in all cases. For regional parameters, it ranged from 0.94 to 0.98 for normal eyes, 0.94 to 1.00 for mild glaucoma eyes, 0.87 to 1.00 for moderate glaucoma eyes, and 0.77 to 0.97 for severe glaucoma eyes. The nasal regions of severe glaucoma appeared to be most variable, as nasal lower region and inferior nasal region had the ICC values of 0.77 and 0.87. CONCLUSION: Reproducibility of RTVue RNFL and ONH measurements was excellent in normal and glaucoma groups.

Measurement of anterior chamber volume with rotating scheimpflug camera and anterior segment optical coherence tomography.

BACKGROUND: Measurement of anterior segment parameters plays an important role in diagnosis and treatment of glaucoma. The objective of this study was to evaluate the repeatability and reproducibility of anterior chamber volume (ACV) measurements with rotating scheimpflug camera (RSC) and to examine agreement with anterior segment optical coherence tomography (AS-OCT). METHODS: Thirty nine healthy normal subjects were recruited from the Eye Center of Tongren Hospital. ACV was measured using RSC and AS-OCT in a randomly selected eye for each subject. For RSC measurements, both automatic and manual ACV measurements and 2 independent operators' ACV measurements were obtained. All subjects were invited for 3 visits within a week to evaluate repeatability and reproducibility of ACV measurement by RSC. Agreement was evaluated between RSC and AS-OCT. RESULTS: Good repeatability and reproducibility were found for both automatic and manual ACV measurements obtained by RSC. For intrasession repeatability, coefficient of variation (CVw) and intraclass correlation coefficient (ICC) values for automatic were 3.52% and 0.98; the values for manual were 3.44% and 0.97, respectively. For intersession reproducibility, the respective CVw and ICC values were 3.96% and 0.96. Good agreement was also found in 2 operators for both automatic and manual ACV measurements; nevertheless, poor agreement was found between RSC and AS-OCT (95% confidence interval (CI) for agreement of automatic RSC measurement versus AS-OCT were -96.3 to 72.8 microl and 95% CI for agreement of manual RSC measurement versus AS-OCT were between -41.7 to 10.1 microl). CONCLUSIONS: Both RSC automatic and manual ACV measurements showed good repeatability and reproducibility, and showed comparable agreement between 2 independent operators, but poor agreement was found between RSC and AS-OCT.

[Clinical research on movement of intraocular contact lens during accommodation].

OBJECTIVE: To study the movement of intraocular contact lens (ICL) during accommodation. METHODS: Forty one eyes of 41 consecutive patients implanted ICL to correct high myopia were collected. The visual acuity and accommodation power were checked before and after the surgery. The movement of both the ICL and the lens was measured separately at nonaccommodated state and pilocarpine induced accommodation. RESULTS: The uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) improved 3 months after surgery. The mean accommodation power before surgery was (2.12 + or - 1.06) D, and was (4.46 + or - 2.11) D 3 months after surgery. Accommodation power was improved significantly (t = 2.312, P = 0.022). The distance from the posterior surface of ICL to the anterior surface of the lens was (0.48 + or - 0.27) mm at nonaccommodated state, and (0.34 + or - 0.19) mm at drug induced accommodation, the difference was significant (t = 2.104, P = 0.038). The position from corneal endothelium to the anterior surface of ICL had no significant difference at nonaccommodated state and drug induced accommodation (t = 1.165, P = 0.149). Depth of the anterior chamber (from the posterior surface of the cornea to the anterior surface of the lens) between nonaccommodated and drug-induced accommodation had no statistically significant difference (t = 1.821, P = 0.071), but the anterior pole of the lens actually moved forward at drug induced accommodation checked with slit lamp. With ultrasound biomicroscopy we could see that in several surgical eyes, ICL loop contacted with periphery lens both in nonaccommodated state and drug induced accommodation condition. CONCLUSIONS: Although the constriction of pupil induced by pilocarpine decreases the distance from the posterior surface of ICL to the anterior lens surface significantly, there still has enough space to avoid the occurrence of subcapsular cataract. The contact between ICL loop and periphery lens might be one of the causes for periphery lens opacification, but the influence of this contact to the occurrence of central subcapsular opacification still requires further investigation.

Accuracy and repeatability of direct ciliary sulcus diameter measurements by full-scale 50-megahertz ultrasound biomicroscopy.

BACKGROUND: Phakic intraocular lens (pIOL) implantation has been a popular means for the treatment of high ametropia. Measurements of ciliary sulcus diameter is important for pIOL size determining. But till now, no perfect system can directly measure it. The present study was to evaluate the accuracy, repeatability and reproducibility of direct sulcus diameter measurements obtained by a full-scale 50-megahertz (MHz) ultrasound biomicroscopy (UBM). METHODS: A fresh cadaver human eye with a scale marker inserted through the posterior chamber plane from 3 o'clock to 9 o'clock meridian and 30 randomly selected eyes from 30 normal subjects were scanned by full-scale 50-MHz UBM in horizontal meridional scan plane. The distance between the scales and the whole length of the marker inside the cadaver eye were measured by the same observer using the "built-in" measurement tools and the indicating error of instrument was calculated. Reproducibility of the measurement was evaluated in 30 eyes by 2 operators using Blander and Altman plot test. Repeatability was evaluated from 10 successive eyes randomly selected from the 30 eyes by one operator. RESULTS: On a scale of 1 mm, the greatest indicating error was 40 microm; the mean largest indicating error of 1 mm scale from the 10 images was (26 +/- 14) microm; on a scale of 11 mm, the greatest indicating error was 70 microm; the error rate was 0.64%. The mean length of the needle inside the eye of the 10 images was 11.05 mm, with the mean indicating error of 47 microm, the average error rate was 0.43%. For ciliary sulcus diameter measurements in vivo, the coefficient of variation was 0.38%; the coefficients of repeatability for intra-observer and inter-observer measurements were 1.99% and 2.55%, respectively. The limits of agreement for intra-observer and inter-observer measurement were -0.41 mm to 0.48 mm and -0.59 mm to 0.58 mm, respectively. CONCLUSION: The full-scale 50-MHz UBM can be a high accuracy and good repeatability means for direct measuring the ciliary sulcus diameter and useful for size determining of posterior chamber pIOL.

[The experimental study of effect of pressure on rat retinal Muller cell in vitro].

OBJECTIVE: To observe the changes of morphology, activity and ability of metabolizing glutamate in Muller cell and investigate the role of Muller cell in the damage induced by glaucoma. METHOD: Cultured Muller cells were divided into two groups at random, one was control group without any treatment, in the experimental group the cells were cultured under pressure of 50 mm Hg (1 mm Hg = 0.133 kPa) for 1 hour, after 3 days additional incubation, the morphology of the cells in two groups was observed by inverse phase microscope and electron microscope, the cells survival were evaluated by MTT colorimetry assay and the expression of mRNA of glutamine synthetase was semi-quantified by RT-PCR. RESULT: No obvious morphology changes were found by inverse phase microscope in the two groups, swelling mitochondrion and Vacuoles in cytoplasm were found in pressured group by electron microscope; the numbers of MTT reading and the mRNA expression in the cells under pressure were decreased, the differences was statistic significance compared with control (P < 0.05). CONCLUSION: Morphology changes were found in the cells under pressure, and the ability of metabolizing glutamate was decreased, which may be one of the reasons of the elevated level of glutamate in the vitreous of glaucoma patients.