Nasolabial fold angle measurement using anterior segment optical coherence tomography in normal subjects.

PURPOSE: The human nasolabial fold angle (NFA) has been measured using MRI and photogrammetry and has been shown to decrease with age. The authors aimed to evaluate a novel method using optical coherence tomography to measure the NFA. METHODS: In this cross-sectional observational series, the authors used anterior segment optical coherence tomography (ASOCT) to image the NFA of both cheeks of 126 subjects aged 21 to 79 years. A dental vinylpolysiloxane custom-designed mould was used as a chin rest. The mean of 3 scans on each side was calculated and analysis of variance, multiple comparisons, and multiple linear regression were carried out using SPSS 11.0. RESULTS: Sixty-one subject (48.4%) were men and 65 (51.6%) were women. Mean age was 50.6 +/- 16.8 years (range, 21-79 years). The ASOCT successfully imaged the NFA in all subjects. Mean right and left NFA were 144.4 degrees +/- 17.1 degrees and 145.4 degrees +/- 17.7 degrees. The NFA were dissimilar between the 6 age categories by decade (p < 0.001). Age was the significant predictor of NFA, accounting for 55% of NFA variation. Every year accounted for a decrease of 0.78 degrees (p < 0.001) and 0.80 degrees (p < 0.001) for the right and left cheeks, respectively. Male sex resulted in an increase in NFA of 5.4 degrees (p = 0.007) and 4.0 degrees (p = 0.06) in the right and left cheeks, respectively. CONCLUSIONS: The NFA decreases with age and increases with male sex and can be measured with ASOCT accurately and easily.

Comparison of gonioscopy and anterior segment ocular coherence tomography in detecting angle closure in different quadrants of the anterior chamber angle.

PURPOSE: To compare the performance of gonioscopy and anterior segment (AS) optical coherence tomography (OCT) in detecting angle closure in the different quadrants of the anterior chamber angle (ACA). DESIGN: Cross-sectional observational study. PARTICIPANTS: Five hundred two consecutive subjects more than 50 years of age with no previous ophthalmic problems recruited from a community clinic in Singapore. METHODS: All subjects underwent gonioscopy and AS OCT imaging in the dark. Using gonioscopy, the ACA was graded using the Scheie system by a single examiner masked to AS OCT findings. MAIN OUTCOME MEASURES: The ACA in a particular quadrant was classified as closed if the posterior trabecular meshwork could not be seen on gonioscopy. A closed ACA on AS OCT imaging was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. RESULTS: After excluding eyes with poor image quality, a total of 423 right eyes were included in the analysis. A closed angle in at least 1 quadrant was observed in 59% of the eyes by AS OCT and in 33% of the eyes by gonioscopy (P<0.001), with fair agreement between the two methods (kappa = 0.40). The frequency of closed angles by AS OCT and gonioscopy were 48% versus 29% superiorly, 43% versus 22% inferiorly, 18% versus 14% nasally, and 12% versus 20% temporally, respectively. Of the 119 of 1692 quadrants that were closed on gonioscopy but open on AS OCT, a steep iris profile was present in 61 (51%) of 119 quadrants on AS OCT, and of the 276 of 1692 quadrants that were open on gonioscopy but closed on AS OCT, 196 (71%) of 276 quadrants showed short iridoangle contact on AS OCT. CONCLUSIONS: The highest rates of closed angles on gonioscopy and AS OCT images were observed in the superior quadrant. Anterior segment OCT tended to detect more closed ACAs than gonioscopy, particularly in the superior and inferior quadrants. Variations in the iris profile and level of iridoangle contact also may explain some of the differences seen between gonioscopy and AS OCT.

Screening for narrow angles in the singapore population: evaluation of new noncontact screening methods.

PURPOSE: To assess the screening effectiveness of 3 new noncontact devices, the scanning peripheral anterior chamber depth analyzer (SPAC) (Takagi, Nagano, Japan), which measures peripheral anterior chamber depth (ACD); IOLMaster (Carl Zeiss Meditec, Jena, Germany), which measures central ACD; and Visante anterior segment optical coherence tomography (AS-OCT) (Visante, Carl Zeiss Meditec, Dublin, CA), which images the angles, and to compare these instruments with gonioscopy in identifying people with narrow angles (NAs). DESIGN: Cross-sectional, observational, community-based study. PARTICIPANTS: Phakic subjects aged >or=50 years without ophthalmic symptoms who were recruited from a community polyclinic in Singapore. METHODS: All subjects underwent examination with SPAC, IOLMaster, and AS-OCT in the dark by a single operator. Gonioscopy was performed by an ophthalmologist masked to the instruments' findings. The area under the curve (AUC) receiver operating characteristic (ROC) was generated to assess the performance of these tests in detecting people with a NA in either eye. MAIN OUTCOME MEASURES: Eyes were classified as having NAs by gonioscopy if the posterior pigmented trabecular meshwork could be seen for

Assessment of the scleral spur in anterior segment optical coherence tomography images.

OBJECTIVE: To assess visibility of the scleral spur in anterior segment optical coherence tomography (AS-OCT) images. METHODS: This cross-sectional observational study included 502 participants aged 50 years or older who had no previous ophthalmic problems and were recruited from a community clinic in Singapore. All participants underwent gonioscopy and AS-OCT (Visante; Carl Zeiss Meditec, Dublin, California). Scleral spur location was assessed in AS-OCT images by 2 examiners with glaucoma subspecialty training and was defined as the point where there was an inward protrusion of the sclera with a change in curvature of its inner surface. RESULTS: Scleral spur location could be determined in 72% of the images of the right eye. Its location on AS-OCT images was less detectable in quadrants with a closed angle on gonioscopy and also in images obtained in the superior and inferior compared with the nasal and temporal quadrants (64%, 67%, 75%, and 80%, respectively; P < .001). CONCLUSIONS: The inability to detect the scleral spur may hamper quantitative analysis of anterior chamber angle parameters that are dependent on the location of this anatomical structure, particularly in the superior and inferior quadrants. New parameters independent of the scleral spur may be useful for detecting eyes at risk of angle closure.

Corneal imaging with anterior segment optical coherence tomography for lamellar keratoplasty procedures.

PURPOSE: To assess and describe the uses of anterior segment optical coherence tomography (OCT) in the evaluation of the cornea before and after lamellar corneal transplantation procedures. DESIGN: Prospective, noncomparative, observational case series. METHODS: Seven eyes of seven patients undergoing anterior and posterior lamellar corneal transplantation procedures at the Singapore National Eye Centre were included in the study. High-resolution anterior segment OCT scans of the cornea and anterior segment were performed both before and after lamellar transplantation procedures on the cornea with the Visante anterior segment OCT system (Visante OCT; Carl Zeiss Meditec, Inc, Dublin, California, USA), and the imaging findings were correlated with the clinical picture. Measurements of lamella thickness were performed with the software provided. RESULTS: Anterior segment OCT images were able to provide valuable information on donor apposition, Descemet membrane detachment after deep anterior lamellar keratoplasty (DALK), posterior lamellar dislocation, primary graft failure, and anterior chamber crowding with consequent chamber angle encroachment and pupillary block after Descemet stripping automated endothelial keratoplasty (DSAEK). CONCLUSIONS: Anterior segment OCT is a valuable imaging tool for assessing the feasibility of lamellar transplantation surgery in the diseased cornea and in the management of surgical complications after such procedures.

Comparison of anterior chamber depth measurements using the IOLMaster, scanning peripheral anterior chamber depth analyser, and anterior segment optical coherence tomography.

AIM: To compare anterior chamber depth measurements by three non-contact devices-the IOLMaster, scanning peripheral anterior chamber depth analyser (SPAC), and Visante anterior segment optical coherence tomography (AS-OCT) METHODS: Prospective, cross sectional study of 497 phakic subjects over 50 years of age attending a community clinic in Singapore. Anterior chamber depth of the right eye was measured using all three techniques by the same investigator. Depth measurements were made from the corneal epithelium to the anterior lens surface. The values obtained were compared using Bland-Altman analysis. RESULTS: 232 men and 265 women were examined (mean (SD) age, 63.4 (7.9) years). Mean anterior chamber depth was 3.08 (0.36) mm with IOLMaster, 3.10 (0.44) mm with SPAC, and 3.14 (0.34) mm with AS-OCT. A significant difference was present between the anterior chamber depth measurements recorded by the three devices (p<0.0001). Mean differences between the measurements were: AS-OCT v IOLMaster, 0.062 (0.007) mm (95% limits of agreement, -0.37 to 0.25 mm) (p<0.0001); AS-OCT v SPAC, 0.035 (0.011) mm (-0.44 to 0.51 mm) (p = 0.0001); SPAC v IOLMaster, 0.027 (0.012) mm (-0.57 to 0.50 mm) (p = 0.027). CONCLUSIONS: AS-OCT gave systematically deeper anterior chamber measurements than SPAC and IOL-Master. However, as the differences found were small they are unlikely to be clinically important.

High-definition optical coherence tomography imaging of the iridocorneal angle of the eye.

OBJECTIVE: To assess the ability of high-definition optical coherence tomography (HD-OCT) to image the anterior chamber angle. METHODS: Forty-five consecutive subjects with phakic eyes underwent gonioscopy and anterior chamber angle imaging with HD-OCT adapted with a 60-diopter aspheric lens mounted over the imaging aperture. The patients' fixation was directed to the side using an external fixation light, and scans were taken of the temporal and nasal quadrants. The visibility of angle structures was assessed and the diagnosis of angle closure using HD-OCT was compared with that of gonioscopy. RESULTS: The majority of subjects were Chinese (91.1%) and female (62.2%). Cross-sectional HD-OCT allowed in vivo visualization of the scleral spur in 71 of 90 quadrants (78.9%) and the termination of the Descemet membrane (Schwalbe line) in 84 of 90 quadrants (93.3%). It was possible to image the trabecular meshwork in 56 quadrants (62.2%). Angle closure was observed in 17 eyes with gonioscopy and 12 eyes with HD-OCT (P = .12, McNemar test). The 2 modalities showed good agreement for angle closure diagnosis by quadrant (kappa = 0.65). CONCLUSION: The adapted HD-OCT provided magnified views of the anterior chamber angle and allowed visualization of the Schwalbe line and trabecular meshwork in most eyes.

Comparison of slitlamp optical coherence tomography and scanning peripheral anterior chamber depth analyzer to evaluate angle closure in Asian eyes.

OBJECTIVE: To evaluate the effectiveness of slitlamp optical coherence tomography (SL-OCT) and Scanning Peripheral Anterior Chamber depth analyzer (SPAC) in detecting angle closure, using gonioscopy as the reference standard. METHODS: A total of 153 subjects underwent gonioscopy, SL-OCT, and SPAC. The anterior chamber angle (ACA) was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen; with SL-OCT, closure was determined by contact between the iris and angle wall anterior to the scleral spur; and with SPAC by a numerical grade of 5 or fewer and/or a categorical grade of suspect or potential. RESULTS: A closed ACA was identified in 51 eyes with gonioscopy, 86 eyes with SL-OCT, and 61 eyes with SPAC (gonioscopy vs SL-OCT, P < .001; gonioscopy vs SPAC, P = .10; SL-OCT vs SPAC, P < .001; McNemar test). Of the 51 eyes with a closed ACA on gonioscopy, SL-OCT detected a closed ACA in 43, whereas SPAC identified 41 (P = .79). An open angle in all 4 quadrants was observed in 102 eyes with gonioscopy, but SL-OCT and SPAC identified 43 and 20 of these eyes, respectively, as having angle closure. The overall sensitivity and specificity for SL-OCT were 84% and 58% vs 80% and 80% for SPAC. CONCLUSION: Using gonioscopy as the reference, SL-OCT and SPAC showed good sensitivity for detecting eyes at risk of angle closure.

Variation of angle parameters in asians: an anterior segment optical coherence tomography study in a population of singapore malays.

PURPOSE: To assess variations in angle parameters using anterior segment optical coherence tomography (AS-OCT) and to investigate demographic, ocular and systemic associations of angle width. METHODS: This was a substudy of a population based, cross-sectional survey of 3280 (78.7% response rate) Malay people aged 40 to 80 years in Singapore. All participants underwent a standardized interview and ocular and systemic examination. AS-OCT was performed on 291 consecutive patients in standardized dark conditions. Angle opening distance (AOD-500) and trabecular-iris space area (TISA-500) 500 microm from the scleral spur were determined for the nasal and temporal angles. Anterior chamber depth (ACD) was also measured. RESULTS: AS-OCT measurements were analyzed in 239 (82.1%) right eyes. Mean AOD 500 was smaller in women than in men, both nasally (0.255 vs. 0.293 mm, P = 0.026) and temporally (0.245 vs. 0.286 mm, P = 0.023). Mean TISA-500 was smaller in women in the nasal quadrant only (0.104 vs. 0.117 mm, P = 0.035). Mean ACD was smaller in women than in men (2.71 vs. 2.87 mm, P = 0.001). Multiple linear regression showed that axial length and ACD were significantly associated with AOD-500 and TISA-500 both nasally (adjusted R(2) = 0.34 for AOD-500 and 0.20 for TISA-500) and temporally (adjusted R(2) = 0.35 for AOD-500 and 0.24 for TISA-500). Body mass index, HbA(1c), systolic blood pressure, intraocular pressure, cup-to-disc ratio, and central corneal thickness were not significantly associated with AOD-500, TISA-500, or ACD. CONCLUSIONS: In this Malay population, angle width measured by AS-OCT was smaller in women than in men, and in eyes with shorter axial length and shallower ACD.

Determinants of angle closure in older Singaporeans.

OBJECTIVES: To investigate systemic and ocular risk factors for angle closure (AC) in older Singaporeans and to determine if these risk factors are different in men vs women and in Chinese vs non-Chinese persons. METHODS: A cross-sectional study of 2042 subjects with phakia 50 years or older recruited from a primary care clinic in Singapore. Subjects completed a detailed questionnaire and underwent refraction, biometry, and gonioscopy. Univariate and multivariate analyses were performed to determine risk factors for AC. RESULTS: The prevalence of AC among this study population was 19.3% (n = 395); 89.4% (n = 1826) of the study population were Chinese. In univariate analysis, patients with AC were older, female, and of Chinese descent and had shorter axial length, lower body mass index, higher intraocular pressure, and shallower anterior chamber depth. In multivariate analysis, female sex (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.06-1.92; P =.02), Chinese race/ethnicity (OR, 3.58; 95% CI, 2.03-6.29; P < .001), axial length (OR per millimeter increase, 0.69; 95% CI, 0.58-0.81; P<.001), and central anterior chamber depth of less than 2.80 mm vs at least 3.00 mm (OR, 42.5; 95% CI, 27.4-66.2; P<.001) were independently associated with AC. CONCLUSIONS: In this community-based study of older Singaporeans, statistically significant independent predictors of AC were female sex, shorter axial length, shallower central anterior chamber depth, and Chinese race/ethnicity. Sex and racial/ethnic differences in the risk of AC were not fully explained by sex and racial/ethnic variations in axial length or anterior chamber depth.