Faculty Bibliography

PURPOSE: To evaluate the effect of laser-assisted in situ keratomileusis on retinal nerve fiber layer thickness measurements obtained with scanning laser polarimetry. METHODS: Thirteen consecutive eyes (13 patients) undergoing laser-assisted in situ keratomileusis were enrolled in this prospective study. Scanning laser polarimetry (NFA-GDx; Laser Diagnostic Technologies, Inc, San Diego, California) examination was performed 1 week before and 1 to 8 weeks after laser-assisted in situ keratomileusis surgery. Intraocular pressure was normal at all preoperative and postoperative examinations. Total mean, and superior, temporal, inferior, and nasal mean retinal nerve fiber layer thickness values before and after laser-assisted in situ keratomileusis were compared by Student paired t test. RESULTS: Mean +/- SD patient age was 34.6 +/- 10.9 years (range, 20 to 56 years). Mean +/- SD preoperative spherical equivalent refractive error was -6.6 +/- 3.1 diopters (range, -3.25 to -13.25 diopters) and mean +/- SD spherical equivalent refractive surgical correction was -6.2 +/- 3.0 diopters (range, -2.9 to -12.25 diopters). Total mean retinal nerve fiber layer and superior, inferior, temporal, and nasal mean retinal nerve fiber layer thicknesses were thinner after laser-assisted in situ keratomileusis (P =.01, for all comparisons, paired t test). CONCLUSIONS: Measurements of the retinal nerve fiber layer with scanning laser polarimetry depend on a corneal compensator inherent in the device. Keratorefractive surgery may affect scanning laser polarimetry measurements

The development of ocular imaging devices has progressed rapidly during the past 10 years. Ultrasound biomicroscopy has revolutionized the evaluation of the anterior segment of the eye. The qualitative information gathered using this technology has contributed to our understanding of the pathophysiology of angle-closure glaucoma, pigmentary glaucoma, and a variety of other anterior segment disorders. However, the area of quantitative analysis of ultrasound biomicroscopic images remains largely to be developed. This review describes the role of ultrasound biomicroscopy in the measurement of the anatomic structures and their configurations within the anterior segment. Included are previously published and established methods as well as methods in their early stages of development. Application of quantitative image analysis techniques should yield significant information about mechanisms of appositional angle closure, dynamic functions of the iris, accommodation, and presbyopia

To develop a reliable method for performing ultrasound biomicroscopy (UBM) in the sitting and prone positions. The probe suspended from an articulated arm was removed and reattached to the arm upside-down for use in the prone position and horizontally for use in the sitting position. A latex Tono-Pen tip cover was attached to the edge of the eyecup and was placed over the transducer through the small hole on the tip of the Tono-Pen tip cover. UBM was successfully performed in the prone and sitting positions with no loss of image quality. This method can expand the ability of the UBM to examine alterations in anatomic relationships among anterior segment structures between the supine, sitting, and prone positions

PURPOSE: To evaluate the relationship between visual function and retinal nerve fiber layer measurements obtained with scanning laser polarimetry and optical coherence tomography in a masked, prospective trial. METHODS: Consecutive normal, ocular hypertensive, and glaucomatous subjects who met inclusion and exclusion criteria were evaluated. Complete ophthalmologic examination, disk photography, scanning laser polarimetry, optical coherence tomography, and automated achromatic perimetry were performed. RESULTS: Seventy-eight eyes of 78 patients (17 normal, 23 ocular hypertensive, and 38 glaucomatous) were enrolled (mean age, 56.8+/-11.5 years; range, 26 to 75 years). Eyes with glaucoma had significantly greater neural network scores on scanning laser polarimetry and lower maximum modulation, ellipse modulation, and mean retinal nerve fiber layer thickness measured with optical coherence tomography compared with normal and ocular hypertensive eyes, respectively (all P<.005). Significant associations were observed between neural network number (r = -.51, r = .03), maximum modulation (r = .39, r = -.32), ellipse modulation (r = .36, r = -.28), and optical coherence tomography-generated retinal nerve fiber layer thickness (r = .68, r = -.59) and visual field mean deviation and corrected pattern standard deviation, respectively. All scanning laser polarimetry parameters were significantly associated with optical coherence tomography-generated retinal nerve fiber layer thickness. CONCLUSION: Optical coherence tomography and scanning laser polarimetry were capable of differentiating glaucomatous from nonglaucomatous populations in this cohort; however considerable measurement overlap was observed among normal, ocular hypertensive, and glaucomatous eyes. Retinal nerve fiber layer structural measurements demonstrated good correlation with visual function, and retinal nerve fiber layer thickness by optical coherence tomography correlated with retardation measurements by scanning laser polarimetry

PURPOSE: To investigate prospectively the relationships between anterior chamber angle configuration and refractive error, axial length, age, and body height in the Japanese. METHODS: We studied 65 eyes of 65 subjects (30 men, 35 women) who were either patients at the Ophthalmology Department of Mie University or volunteers. The 65 subjects underwent a complete eye examination, A-scan biometry, and ultrasound biomicroscopy. Images were exported to an IBM-compatible personal computer in PCX format. The angle recess area (ARA) was measured using a software program of our own design. RESULTS: The ARA decreased with age in all quadrants of all eyes. In older individuals, the angle in the superior quadrant was significantly narrower than in the other quadrants. The ARA correlated directly with anterior chamber depth (P < .001), axial length (P < .001), and body height (P = .003), and inversely with age (P < .001) and refractive error (P = .003) in pairwise analysis. Multivariate analysis revealed a significant association between ARA and anterior chamber depth (P < .001), axial length (P = .016), and younger age (P = .043). CONCLUSIONS: The anterior chamber area narrows with age, especially in the superior quadrant. Narrowing of the angle in Japanese is associated with older age, shorter axial length, and shallower anterior chamber depth. We hypothesize that because of the increasing prevalence of axial myopia in younger Japanese, angle-closure glaucoma could become less common in Japan in the future

BACKGROUND: To describe the ultrasound biomicroscopic (UBM) features of anterior segment cysts. DESIGN: A retrospective case series. PARTICIPANTS: One hundred eighteen eyes with anterior segment cysts examined by UBM at The New York Eye and Ear Infirmary between August 1992 and November 1997 were included in this study. INTERVENTION: The authors reviewed demographic and diagnostic data from the medical record including ocular and medical history, age, race, gender, and intraocular pressure. Ultrasound data concerning the type, number, position, and acoustic characteristics of cysts were recorded. The authors then correlated the written, clinical, and UBM characteristics. RESULTS: One hundred eyes (92.6%) had neuroepithelial cysts. Ninety (83.3%) of these had primary neuroepithelial cysts, 10 (9.3%) had cysts associated with uveitis, 7 (6.5%) had implantation cysts, and 1 (0.9%) had a cavitated ciliary body tumor. Neuroepithelial cysts typically were round or ovoid, thin-walled, and echolucent. Of the 90 eyes with primary neuroepithelial cysts, 56 (62.2%) had 3 or fewer cysts; multiple cysts (>3 per eye) were found in 34 eyes (37.8%). The multiple cysts occupied more than 180 degrees in 12 patients (13.3%). Primary neuroepithelial cysts were located at the iridociliary junction (74.2%), pars plicata (14.0%), pars plana (6.8%), and iris (5.0%). Implantation cysts (seven eyes) tended to have thicker walls and two contained a copious, echogenic material. CONCLUSION: The UBM results provide important information regarding location and extent of anterior segment cystic lesions. Ultrasound characteristics may help differentiate between neuroepithelial, implantation, and neoplastic cysts

PURPOSE: To describe a quantitative method for measuring the iridocorneal angle recess area, and, using this, to evaluate factors associated with appositional angle-closure during dark room provocative testing using ultrasound biomicroscopy (UBM). METHODS: All patients (178 patients, 178 eyes) with clinically narrow angles referred for UBM dark room provocative testing between September 1996 and March 1998 were enrolled in this study. Images of the inferior quadrant of the angle taken under standardized dark and light conditions were analyzed. The angle recess area (ARA) was defined as the triangular area demarcated by the anterior iris surface, corneal endothelium, and a line perpendicular to the corneal endothelium drawn from a point 750 microm anterior to the scleral spur to the iris surface. ARA, and acceleration and gamma-intercept of the linear regression analysis of the ARA were calculated. In the linear regression formula, y = ax + b, the acceleration a describes the rate at which the angle widens from the scleral spur; the y-intercept b describes the distance from the scleral spur to the iris. RESULTS: Under dark conditions, the angles in 99 patients (55.6%) showed evidence of appositional angle-closure during testing. ARA (0.11 +/- 0.04 vs. 0.15 +/- 0.05 mm2, P < .0001, Student t-test), acceleration a (0.22 +/- 0.15 vs. 0.26 +/- 0.17, P = .068), and y-intercept b (66 +/- 46 vs. 92 +/- 47 microm, P = .0003) were smaller in eyes that were occluded. In the eyes that were not occluded, y-intercept b showed no significant difference between light and dark conditions (P = .1, paired t-test), while acceleration a did (P < .0001). In the eyes that were occluded, both decreased significantly under dark conditions (P < .0001). CONCLUSIONS The ARA linear regression formula provides useful quantitative information about angle recess anatomy. The more posterior the iris insertion on the ciliary face, the less likely the provocative test will be positive

PURPOSE: To evaluate optic disc and retinal nerve fiber layer (RNFL) appearance in normal, ocular-hypertensive, and glaucomatous eyes undergoing confocal scanning laser ophthalmoscopy and optical coherence tomography (OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS: Seventy-eight eyes of 78 consecutive normal (n = 17), ocular-hypertensive (n = 23), and glaucomatous subjects (n = 38) were enrolled. METHODS: Each patient underwent complete ophthalmic examination, achromatic automated perimetry, confocal scanning laser ophthalmoscopy (Heidelberg Retinal Tomography [HRT]), and OCT. Topographic HRT parameters (disc area, cup-disc ratio, rim area, rim volume, cup shape measure, mean RNFL thickness, and cross-sectional area) and mean OCT-generated RNFL thickness were evaluated in each group. MAIN OUTCOME MEASURES: OCT and HRT assessment of optic disc and RNFL anatomy. RESULTS: OCT RNFL thickness showed no difference between normal and ocular-hypertensive eyes (P = 0.15) but was significantly less in glaucomatous eyes (P < 0.001). HRT measurements of rim area, cup-disc ratio, cup shape measure, RNFL thickness, and RNFL cross-sectional area were significantly less in glaucomatous eyes (all P < 0.005) and were correlated with mean OCT RNFL thickness (all P < 0.02). RNFL thickness using OCT or HRT was highly correlated with visual field mean defect during achromatic perimetry (P < 0.0001). CONCLUSION: Both HRT and OCT can differentiate glaucomatous from nonglaucomatous eyes. RNFL thickness measurements using OCT correspond to disc topographic parameters using HRT

PURPOSE: Published series of peripapillary retinal nerve fiber layer (RNFL) measurements using optical coherence tomography (OCT) have sampled 100 evenly distributed points on a 360 degrees peripapillary circular scan. The goal of this study was to determine whether a four-fold increase in sampling density improves the reproducibility of OCT measurements. METHODS: Complete ophthalmic examinations, achromatic automated perimetry, and OCT imaging were performed in all patients. The OCT scanning consisted of three superior and inferior quadrantic scans (100 sampling points/quadrant) and three circular scans (25 points/quadrant). The RNFL thickness measurements and coefficient of variation (CV) were calculated for the superior and inferior quadrants for each sampling density technique. RESULTS: The study included 22 eyes of 22 patients (3 control subjects; 2 patients with ocular hypertension; and 17 patients with glaucoma). Quadrants with associated glaucomatous visual field loss on automated achromatic perimetry had thinner RNFLs than quadrants without functional defects for both the 25- and 100-points/quadrant scans. For quadrants associated with normal visual hemifields (n = 22), there was no difference between the 25- and 100-points/quadrant scans in mean RNFL thickness and CV. Among quadrants with visual field defects (n = 22), RNFL thickness measurements were thinner in the 25-points/quadrant scans than in the 100-points/quadrant scans. The CV for the 25-points/quadrant scans (25.9%) was significantly higher than that for the 100-points/quadrant scans (11.9%). CONCLUSION: Increasing the sampling density of OCT scans provides less variable representation of RNFL thickness. The optimal sampling density to achieve maximal reliability of OCT scans remains to be determined