The association of membrane frizzled-related protein (MFRP) gene with acute angle-closure glaucoma--a pilot study.

PURPOSE: The membrane frizzled-related protein (MFRP) has been proposed as a probable candidate gene for extreme hyperopia and nanophthalmos, which are factors for angle-closure glaucoma. The purpose of our study was to investigate whether there are significant associations between angle-closure glaucoma and sequence variants in the MFRP gene reported previously in Taiwanese subjects. METHODS: Genomic DNA was collected from 63 subjects with angle-closure glaucoma and 66 age-matched and gender-matched controls without angle-closure glaucoma. Three sequence variants were detected by polymerase chain reaction (PCR) and direct sequencing in all of the cases and controls. RESULTS: None of the three sequence variants showed a significant result in terms of association with disease. The pairwise linkage disequilibrium (LD) mapping confirmed that these alleles have a comparatively strong LD index greater than 0.7 for D' and greater than 0.4 for r(2) at these polymorphisms. However, we found there were no statistical associations between any of the three sequence variants located on MFRP and angle-closure glaucoma. CONCLUSIONS: In our pilot study, variations that we tested in MFRP were not associated with the development of acute angle-closure glaucoma in Taiwanese subjects.

Comparing glaucomatous optic neuropathy in primary open angle and primary angle closure glaucoma eyes by scanning laser polarimetry-variable corneal compensation.

PURPOSE: To study the retinal nerve fiber layer thickness difference between high-tension primary open angle glaucoma (HT-POAG) and primary angle closure glaucoma (PACG) eyes using scanning laser polarimetry-variable corneal compensation (GDx VCC) in Taiwan-Chinese population; to evaluate the usefulness of the GDx VCC for detecting POAG and PACG eyes in Taiwan-Chinese population. PATIENTS AND METHODS: The study comprised 88 early to moderate glaucomatous eyes (one randomly selected eye from 47 HT-POAG patients and 41 PACG patients) and the control group consisted of 45 age-matched eyes from 45 normal individuals. Each subject underwent retinal nerve fiber layer thickness measurement by GDx VCC and Humphrey Field Analyzer visual field testing. Measured GDx VCC parameters were compared among groups. We also calculated the area under the receive operator characteristic (AROC) curve, corresponding sensitivity/specificity and best cut off value for each parameter in differentiating normal from POAG and PACG eyes. RESULTS: There was no significant difference between HT-POAG and PACG eyes in each parameter. The parameter with the best AROC curve for differentiating normal from POAG eye was nerve fiber indicator (AROC, 0.779; sensitivity=57.4%, specificity=100%; best cut off value >27). The parameter with the best AROC curves for differentiating normal from PACG eyes was temporal-superior-nasal-inferior-temporal average (AROC, 0.829; sensitivity=46.3%, specificity=100%, best cut off value <51.7). CONCLUSIONS: There was no significant difference between the HT-POAG and PACG eyes as far as the various parameters were concerned. GDx VCC shows fair discriminating ability in distinguishing normal from POAG and PACG eyes in Taiwan Chinese population.

Ocular biometry in acute and chronic angle-closure glaucoma.

AIM: To evaluate the biometric difference between eyes with acute angle-closure (AAC) attack, their uninvolved fellow eyes and eyes with chronic angle-closure glaucoma (CACG). METHODS: Patients with prior laser iridotomy on both eyes for unilateral AAC attack or CACG were recruited. We compared ocular biometric parameters by A-scan ultrasonography of the acutely affected eyes with those of the uninvolved fellow eyes and with eyes affected by CACG. RESULTS: Thirty-three patients with unilateral AAC attack and 41 patients with CACG were included. The eyes with AAC attack had a significantly shallower anterior chamber depth (ACD), thicker lens, shorter axial length, higher lens/axial length factor and more anteriorly positioned lens than the eyes with CACG. The uninvolved fellow eyes had a significantly shallower ACD, shorter axial length and higher lens/axial length factor compared with the eyes with CACG. Acutely affected eyes had a shallower ACD and more anteriorly positioned lens than did the uninvolved fellow eyes. CONCLUSION: Eyes with AAC attack had a more crowded anterior segment compared with uninvolved fellow eyes and those affected by CACG. In addition to ACD, relative lens size, represented by the lens/axial length factor, and relative lens position appear to play important roles in the development of AAC attack.

The association of single nucleotide polymorphisms in the MMP-9 genes with susceptibility to acute primary angle closure glaucoma in Taiwanese patients.

PURPOSE: To study the relationships between single nucleotide polymorphisms (SNPs) of extracellular matrix, matrix metalloproteases (MMPs), tissue inhibitors of MMPs, and other glaucoma-associated genes and acute primary angle closure glaucoma (PACG). METHODS: We extracted DNA samples from 78 adult patients with acute PACG and 86 control subjects to study the relationships between these specific genes and acute PACG. Genotyping was performed for 35 genes by the GenomeLab SNPstream genotyping system after PCR amplification of chromosomal DNA. The association between these genetic polymorphisms and risk of primary PACG was estimated by chi2 and logistic regression. RESULTS: The genotyping success rate was 99%. Genotyping for the MMP9 site (rs2664538) was significantly different between the two groups (p=0.000001) and the odds ratio was 2.586 (95% CI: 1.715-3.898, p<0.00001). However, there were no associations of SNPs to other genes in patients with acute PACG. CONCLUSIONS: Our results reveal that SNP rs2664538, which is located at the MMP9 gene, is likely to be associated with acute PACG.

Prevalence of anisometropia in Taiwanese schoolchildren.

BACKGROUND AND PURPOSE: This study investigated the prevalence and distribution of anisometropia in Taiwanese schoolchildren using nationwide data from refractive surveys performed in 1995 and 2000. METHODS: Complete survey data was obtained for 11,175 students in 1995 and 10,878 students in 2000. The refractive status of each student was measured using an autorefractometer under cycloplegia and rechecked with retinoscopy. The difference in refractive status between each participant's eyes was determined. Chi-squared statistic was used to assess the difference between the 2 surveys. Multiple linear regression was used to determine the trend and effects of covariates. RESULTS: Most of the schoolchildren (77.6% in 1995, 71.9% in 2000) were not anisometropic. Most of the anisometropic differences were in the range 0.5 to 1.0 D (14.1% in 1995 vs 17.9% in 2000). About 6% of schoolchildren in 1995 and 7.0% in 2000 had anisometropic differences in the range from -1.0 to -2.0 D. Fewer than 4% of students had a level of anisometropia greater than 2.0 D (2.7% vs 3.2%, respectively). The prevalence of anisometropia and the extent of anisometropic difference both increased with age and with maximal myopic refraction (both p < 0.0001). Both the prevalence and extent of anisometropia showed significant differences between the 2 surveys (both p < 0.0001). CONCLUSIONS: Most of the Taiwanese schoolchildren surveyed were non-anisometropic. The prevalence and amount of anisometropia were significantly increased from 1995 to 2000. The mechanisms responsible for these increases have not been determined, but may be related to increase of myopic refraction.

Ultrasound biomicroscopic findings in rabbit eyes undergoing scleral suction during lamellar refractive surgery.

PURPOSE: To evaluate changes of the central anterior chamber depth, cilio-angular cross-sectional surface area, and intraocular pressure in rabbit eyes undergoing application of the scleral suction ring during lamellar refractive surgery. METHODS: Thirty eyes of 30 rabbits were used in the study. The eyes were assigned to one of the following five surgical groups: group 1, no application of the suction ring; group 2, suction for 2 minutes; group 3, suction for 1 minute; group 4, suction for 20 seconds; and group 5, suction for 10 seconds. Ultrasound biomicroscopy (UBM) was performed to determine tomographic features, including central anterior chamber depth, cross-sectional surface area of the ciliary body, and chamber angle structure before and 10 minutes, 1 hour, 2 hours, 1 day, 2 days, 1 week, and 2 weeks after surgery. Intraocular pressure was also measured at each of these time points. RESULTS: Swelling of the ciliary body occurred in groups 2 to 5 of eyes from 10 minutes up to 1 day after the operation, and its severity was positively related to the duration of suction. Shallowness of the chamber angle was positively related to swelling. All UBM-detectable changes became insignificant compared with baseline values at 2 days after the operation. No significant change was found in the central anterior chamber depth and intraocular pressure during the 2-week postoperative observation period. CONCLUSIONS: Transient change in the ciliary body and the chamber angle occurred frequently after application of the scleral suction ring during lamellar refractive surgery in rabbit eyes. Its severity was positively related to the duration of suction. Swelling of the ciliary body corresponded with the shallowness of the chamber angle without alteration of the corneal-lenticular distance and intraocular pressure.

Characteristics of optic disc changes in Taiwanese patients with primary angle-closure glaucoma.

BACKGROUND AND PURPOSE: Primary angle-closure glaucoma (PACG) is the predominant form of glaucoma among Asians. Although numerous studies have been done to describe the characteristic optic disc changes in patients with primary open angle glaucoma (POAG) which is the predominant form of glaucoma among Western populations, few studies have evaluated the optic disc changes in patients with PACG. The aim of this study was to elucidate the characteristic intrapapillary and parapapillary disc changes in PACG in a cross-sectional study and to develop a practical approach to the detection of glaucomatous optic disc changes in PACG by ophthalmoscopic examination. METHODS: A total of 103 eyes in 103 PACG patients were studied. Forty one eyes of 41 age- and sex-matched healthy subjects served as controls. Three glaucoma-trained subspecialists examined stereophotographs of optic discs to evaluate the intrapapillary and parapapillary changes. The differences in PACG and control group eyes were compared. RESULTS: Concentric steep enlargement of the optic disc was found in 99 PACG eyes (96%). Local notching was noted in only 3 eyes, and vertically oval-shaped cupping of the optic disc in only 1 eye. Disc hemorrhage was not detected in any eye. Parapapillary atrophy of the alpha zone involving both temporal and nasal side of the optic disc and parapapillary atrophy of beta zone were significantly more frequent in the PACG group. The presence of an alpha zone or a beta zone simultaneously involving both the temporal and nasal side of the optic disc was associated with more severe optic nerve head damage. CONCLUSIONS: The intrapapillary change in the PACG group eyes reflected the development of cupping in PACG patients with small and compact optic discs. The parapapillary atrophy paralleled the intrapapillary optic disc cupping in eyes of the PACG group.

Comparing myopic progression of urban and rural Taiwanese schoolchildren.

PURPOSE: To compare myopic progression rates in Taiwanese schoolchildren between urban and rural areas. METHODS: Several longitudinal studies of myopic progression were performed in urban and rural areas. Five primary schools, four junior high schools, and two senior high schools were selected from both urban and rural areas. Ages ranged from 7 to 18 years. The refractive state of each student was measured with an autorefractometer under cycloplegia. RESULTS: Mean myopic progression in primary school children (ages 7 to 12) in the urban areas was around 0.20 D/year for boys and 0.27 D/year for girls. The mean myopic progression rate in urban children from primary to junior high school age (ages 10 to 15) was 0.43 D/year for boys and 0.50 D/year for girls, faster than that in rural children (0.24 and 0.31 D/year, respectively). The average progression rate was fastest in children in junior high school (ages 13 to 15), around 0.45 D/year in urban areas and 0.28 D/year in rural areas. In senior high schools (ages 16 to 18), myopic progression slowed to 0.17 D/ year in boys and 0.33 D/year in girls. Myopic progression in all groups was faster in myopic eyes than in emmetropic or hyperopic eyes. CONCLUSIONS: The average myopic progression in urban areas was greater than that in rural areas. Environmental factors such as urban development and academic grade level may be important contributing factors to myopic progression.

Diagnostic value of GDx polarimetry in a Taiwan Chinese population.

PURPOSE: To study the diagnostic ability of scanning laser polarimetry with variable corneal compensation (GDx VCC) for early glaucomatous (EG) eyes and glaucoma-suspect (GS) eyes in a Taiwan Chinese population. METHODS: This prospective cross-sectional study included 82 EG eyes (mean deviation, MD: -3.32 +/- 2.20 dB), 45 GS eyes (MD: -2.43 +/- 2.16 dB), and 62 normal eyes. Retinal nerve fiber layer thickness of each subject was measured using GDx VCC and Humphrey Field Analyzer visual field testing. Measured GDx VCC parameters were compared among groups. The area under the receiver operating characteristic (AROC) curve of each parameter was used to differentiate normal from EG eyes or GS eyes. The correlation between MD and each parameter was also evaluated. RESULTS: For both normal versus EG and normal versus GS, the largest AROC values were for nerve fiber indicator, superior average thickness, and inferior average thickness. There was no significant correlation between MD and GDx-VCC-measured parameters either in EG or GS eyes. CONCLUSIONS: GDx VCC shows only moderate ability to distinguish normal eyes from eyes with early glaucoma. However, its diagnostic role in eyes with suspicious discs and normal visual fields is uncertain at this moment in the Taiwan Chinese population. Further studies are needed to address this issue.

Early treatment of severe cystoid macular edema in central retinal vein occlusion with posterior sub-tenon triamcinolone acetonide.

PURPOSE: To evaluate the clinical outcomes of posterior sub-Tenon (PST) injection of triamcinolone acetonide (TA) in the early treatment of severe cystoid macular edema (CME) in central retinal vein occlusion (CRVO). METHODS: In a noncomparative, prospective study, 18 eyes of 18 patients with severe CME (central macular thickness, CMT >450 microm) secondary to recent-onset CRVO (the onset of symptoms < or =4 weeks) and a decrease in visual acuity (< or =80 letters of Early Treatment Diabetic Retinopathy Study [ETDRS] scores, 20/50) were included. PST injection of 40 mg of TA was given under topic anesthesia. All patients received three biweekly injections and were evaluated at baseline and at 1 day, 1, 2, 4, 6, and 8 weeks, and 3, 6, and 9 months after injection. The main outcome measures were ETDRS scores, CMT, intraocular pressure (IOP), cataract progression, and frequency of complications. RESULTS: The mean age of the 18 patients was 61.17 years (range, 24-81 years) and the mean duration of symptoms was 15.28 days (range, 9-28 days). Eight eyes were diagnosed with ischemic CRVO and 10 eyes with nonischemic CRVO. Mean baseline ETDRS visual acuity (VA) score was 36.89 +/- 18.22 in all affected eye. There was a significant improvement in VA at 1, 3, 6, and 9 months of follow-up. The mean VA at these time points were 46.61 +/- 20.21, 58.11 +/- 22.19, 59.39 +/- 22.98, and 58.67 +/- 23.27 (all P < 0.001), respectively. Both nonischemic and ischemic eyes benefited with a statistically significant VA improvement at each time point. A comparison of the gain in VA between two subgroups was not significant at 1 and 3 months (P > 0.05), but was statistically significant at 6 and 9 months (P = 0.009 and 0.008, respectively). VA gain of 10 or more letters was found in all nonischemic eyes (10/10) and 3 ischemic eyes (3/8) at the 9-month follow-up. Two ischemic eyes were found to have no gain of letters in VA at the 9-month follow-up. The mean baseline CMT for all eyes was 566 +/- 42 microm. There was a 29% reduction with a mean CMT of 404 +/- 49 microm (P < 0.001) at 1 month, 51% reduction with a mean CMT of 278 +/- 40 microm (P < 0.001) at 3 months, 61% reduction with a mean CMT of 222 +/- 56 microm (P < 0.001) at 6 months, and 63% reduction with a mean CMT of 210 +/- 30 microm (P < 0.001) at 9 months. Both nonischemic and ischemic eyes demonstrated a statistically significant reduction in CMT (all P < 0.001). A comparison of the reduction in CMT between these two subgroups was not significant at each visit (all P > 0.05). For both subgroups, there was no statistically significant difference in IOP change at baseline, 1 week, 1, 3, 6, and 9 months of follow-up. Only two patients required topic antiglaucoma drops for elevated IOP. Three patients developed a recurrence of CME accompanied with visual decrease. No cataract progression or other complications were observed. CONCLUSIONS: PST injection of TA is effective in reversing CME and improving visual acuity in recent-onset CRVO in the first 9 months. Patients with nonischemic CRVO may respond more favorably than patients with ischemic CRVO. Early treatment may be better for visual improvement before longstanding macular edema results in irreversible photoreceptor damage. Further study with longer follow-up period is necessary.

Logistic regression analysis for glaucoma diagnosis using Stratus Optical Coherence Tomography.

PURPOSES: The purposes of this study are to investigate the diagnostic performance of logistic regression analysis (LRA) applied to multidimensional information on glaucoma disease and to determine the area under receiver operator characteristic curves (AROCs) for differentiating between normal and glaucomatous eyes in the Taiwan Chinese population based on the summary data from the Stratus Optical Coherence Tomography (OCT). METHODS: One randomly selected eye from each of the 89 patients with glaucoma and from each of the 88 age- and gender-matched normal individuals were included in the study. Nine glaucomatous eyes and eight normal eyes were excluded as a result of poor OCT scans. Finally, 80 normal eyes and 80 glaucomatous eyes (mean deviation, -4.5 +/- 4.12 dB) were analyzed. The whole dataset was split into four equal sets. Each set combines 20 patients with glaucoma and 20 normal individuals. Fourfold crossvalidation was conducted. Retinal nerve fiber layer thickness and optic nerve head were measured by Stratus OCT in each patient. Twenty-five OCT parameters were included in a LRA method to determine the best combination of parameters for discriminating between glaucomatous and healthy eyes based on AROCs. RESULTS: With the LRA method, the AROC for glaucoma detection was 0.911 with sensitivity at 80% and 90% specificity were 83.7% and 80.0%, respectively. CONCLUSIONS: Compared with the OCT-provided parameters, the LRA method improved the ability to differentiate between normal and glaucomatous eyes in the Taiwan Chinese population.

The prevalence of astigmatism in Taiwan schoolchildren.

PURPOSE: To understand the prevalence and distribution of astigmatism in schoolchildren in Taiwan, we analyzed and compared the nationwide survey data in 1995 and 2000. METHODS: A total of 11,175 students were enrolled in 1995, and 10,878 students were enrolled in 2000. The refractive status of each student was measured with an autorefractor during cycloplegia and rechecked with retinoscopy. RESULTS: About half of schoolchildren (57.5% in 1995 and 49.0% in 2000) had no astigmatism (<0.5 D). About one third of schoolchildren's astigmatism was <1 D (27.9% vs. 32.6%). Eleven percent of schoolchildren in 1995 and 13% in 2000 had astigmatism between 1.0 and 2.0 D. Less than 2% of students had astigmatism >3.0 D (1.3% in 1995 and 1.8% in 2000). Most astigmatism was with-the-rule: 83.3% in 1995 and 89.9% in 2000. Only 16.6% of children in 1995 and 9.7% in 2000 had against-the-rule astigmatism. Very little astigmatism was oblique (0.1% in 1995 and 0.4% in 2000). The rate of myopic astigmatism increased with age. In contrast, the rate of hyperopic and mixed astigmatism decreased with age. In addition, the rate of with-the-rule astigmatism increased and the rate of against-the-rule decreased with respect to age, but oblique astigmatism was rather stable with age. CONCLUSIONS: Most schoolchildren had little or no astigmatism. In Taiwan, most astigmatism is <1 D and is myopic with-the-rule astigmatism. There was more myopic astigmatism and with-the-rule astigmatism in 2000 than in 1995.

Ciliary detachment after pars plana vitrectomy: an ultrasound biomicroscopic study.

PURPOSE: To determine the incidence, duration, risk factors, and clinical outcomes for ciliary detachment after pars plana vitrectomy (PPV). METHODS: A total of 109 eyes of 103 patients who underwent PPV for various disease entities were included. Ultrasound biomicroscopy was applied to determine the tomographic features of the ciliary body before and 1, 3, and 7 days after the surgery. All eyes were then examined once weekly for 2 months. Demographic, preoperative, intraoperative, and postoperative parameters were evaluated to assess their predictive value in the formation of postvitrectomy ciliary detachment. RESULTS: Ciliary detachment was observed in 46 eyes (42%) after surgery and persisted for less than 3 weeks in 40 of 46 eyes. It most frequently occurred in eyes of patients with proliferative diabetic retinopathy (PDR) (64%) or retinal vascular obstructive diseases (RVO) (47%). Extensive retinal photocoagulation and retinal cryopexy positively predisposed to its formation whereas fluid-gas exchange had a protective effect. No clinical complications were observed in eyes with postoperative ciliary detachment. CONCLUSION: Ciliary detachment occurred frequently after PPV. A diagnosis of PDR or RVO and surgical procedures with extensive retinal photocoagulation and retinal cryopexy may have a higher incidence of its occurrence.