Effect of a tight necktie on intraocular pressure.

AIM: To evaluate the effect of a tight necktie on intraocular pressure (IOP) measurement using Goldmann applanation tonometry. METHODS: 40 eyes of 20 normal subjects and 20 open angle glaucoma patients (all male) were enrolled. IOP was measured with an open shirt collar, 3 minutes after placing a tight necktie, and 3 minutes after loosening it. All measurements were made by the same examiner. RESULTS: Mean IOP in normal subjects increased by 2.6 (SD 3.9) mm Hg (p=0.008, paired t test; range -3 to +14 mm Hg) and in glaucoma patients by 1.0 (1.8) mm Hg (p=0.02, paired t test; range -2 to +4.5 mm Hg). In normal subjects, IOP in 12 eyes was increased by >/=2 mm Hg and in seven eyes by >/=4 mm Hg. In glaucoma patients, IOP in six eyes was increased by >/=2 mm Hg and in two eyes by >/=4 mm Hg. CONCLUSION: A tight necktie increases IOP in both normal subjects and glaucoma patients and could affect the diagnosis and management of glaucoma.

Retinal nerve fiber layer thickness remains unchanged following laser-assisted in situ keratomileusis.

PURPOSE: To evaluate the effect of laser-assisted in situ keratomileusis (LASIK) on retinal nerve fiber layer (RNFL) thickness measurements obtained with scanning laser polarimetry (SLP), optical coherence tomography (OCT), and scanning laser tomography (SLT). DESIGN: Interventional case series. METHODS: Twenty eyes (20 patients) undergoing LASIK were enrolled in this prospective study. SLP, OCT, and SLT examinations were performed 1 week prior to and 1 week and 4 weeks after LASIK surgery. Intraocular pressure was normal at all preoperative and postoperative examinations. SLP, OCT, and SLT mean RNFL thickness values, and SLT RNFL cross sectional area, rim area, and rim volume before and after LASIK were compared by the Student paired t test. RESULTS: Mean patient age was 39.3 +/- 9.5 (SD) years (range, 28 to 62 years). Mean preoperative spherical equivalent refractive error was -3.9 +/- 1.9 diopters (D) (range, -1.4 to -8.00 D) and mean spherical equivalent refractive surgical correction was 3.6 +/- 1.9 D (range, 1.00 to 8.50 D). Mean RNFL thicknesses obtained by SLP were thinner 1 week and 4 weeks after LASIK (P < 0.01, for all comparisons, paired t test), whereas mean OCT RNFL thickness and SLT RNFL thickness, RNFL cross-section area, rim area, and rim volume measurements were unchanged 1 week and 4 weeks after LASIK (P > or = 0.05, for all comparisons, paired t test). CONCLUSIONS: LASIK does not affect RNFL thickness. Alterations in SLP RNFL thickness measurements are due to alterations in corneal architecture rather than an actual LASIK-induced RNFL injury.

Attempted eyelid closure affects intraocular pressure measurement.

PURPOSE: To evaluate the effect of attempted eyelid closure on intraocular pressure measurement. METHODS: Normal subjects underwent intraocular pressure measurement in both eyes using Goldmann applanation tonometry and Tono-pen XL (Mentor, Inc, Norwell, Massachusetts) by the same examiner holding the eyelids open, both with and without the subject simultaneously attempting forced eyelid closure. Subjects were seated during all measurements and waited 5 minutes between measurements with each instrument; the order of measurement was randomized. RESULTS: Thirty eyes of 15 subjects (six men, nine women) were enrolled. Mean age was 30.5 +/- 5.2 years (range, 24 to 40 years). With Goldmann applanation tonometry, intraocular pressure increased in both eyes with attempted eyelid closure by a mean of 1.5 +/- 2.0 mm Hg (P =.0002, paired t test; range, -2 to 8 mm Hg). With the Tono-pen XL, intraocular pressure also increased in both eyes with attempted eyelid closure by a mean of 1.9 +/- 2.7 mm Hg (P =.0002, paired t test; range, -2 to 9 mm Hg). Tono-pen XL mean intraocular pressure values in both eyes (14.4 +/- 2.3 mm Hg) consistently overestimated those of Goldmann applanation tonometry (13.0 +/- 2.2 mm Hg) by a mean of 1.4 +/- 2.3 mm Hg. CONCLUSIONS: Attempted forced eyelid closure is a common and statistically significant source of error in routine outpatient measurement of intraocular pressure and could influence clinical management of glaucoma.

Assessment of retinal nerve fiber layer internal reflectivity in eyes with and without glaucoma using optical coherence tomography.

OBJECTIVE: To assess the internal reflectivity of the retinal nerve fiber layer in normal, ocular hypertensive, and glaucomatous eyes using optical coherence tomography. METHODS: All patients underwent complete ophthalmic examination and achromatic automated perimetry. Intraocular pressure was 21 mm Hg or less for low-tension glaucoma and normal eyes and at least 25 mm Hg on 2 separate occasions in ocular hypertensive and high-tension glaucoma eyes. All glaucomatous eyes had characteristic glaucomatous optic neuropathy and associated achromatic automated perimetry defect. Relative retinal nerve fiber layer internal reflectivity was measured on optical coherence tomography images using a software program of our own design. RESULTS: We enrolled 98 eyes (19 normal, 34 ocular hypertensive, 17 high-tension glaucoma, and 28 low-tension glaucoma). Relative internal reflectivity was less in eyes with glaucoma than in normal (P<.001, t test) and ocular hypertensive eyes (P<.001, t test). There was no difference in relative internal reflectivity between normal and ocular hypertensive eyes (P =.32) and between eyes with high-tension glaucoma and low-tension glaucoma (P =.43). Internal reflectivity correlated with mean deviation on achromated automatic perimetry (r(2) = 0.49, P<.001, quadratic regression analysis). CONCLUSION: Relative retinal nerve fiber layer internal reflectivity may provide useful information about the extent of retinal nerve fiber layer injury in glaucoma. Arch Ophthalmol. 2000;118:1044-1047

Grayscale and proportion-corrected optical coherence tomography images.

BACKGROUND AND OBJECTIVE: The commercially available optical coherence tomography (OCT) scanner displays images in a pre-set window regardless of the projected scan length on the retinal surface. The aim of this study was to demonstrate the true dimensions of proportion-corrected OCT images and the additional information present in grayscale images. MATERIALS AND METHODS: OCT raw data were exported to an IBM-compatible PC and processed to show grayscale and proportion-corrected images using an automated software of our own design. RESULTS: Eyes with cystoid macular edema and retinal pigment detachment were analyzed. Grayscale images showed a finer gradation of signal reflectance. Scan lengths of 2, 4, 6, and 8 mm on the retinal surface showed different qualitative appearances using proportion-corrected software from the printed or on-screen images. CONCLUSIONS: Grayscale OCT images can be used to demonstrate additional information not present in false-color images. The disparity between the standard OCT image format and proportion-corrected images emphasizes the need for quantitative rather than qualitative evaluation of retinal dimensions and internal reflectance.

Scanning laser polarimetry measurements after laser-assisted in situ keratomileusis.

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.

Increasing sampling density improves reproducibility of optical coherence tomography measurements.

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.

Chronic dacryoadenitis misdiagnosed as eyelid edema and allergic conjunctivitis.

PURPOSE: To report the case of a 53-year-old woman with a 2-year history of episodic upper eyelid swelling and nonspecific complaints, who was diagnosed as having allergic conjunctivitis. METHODS: A complete ocular examination, orbital computerized tomographic (CT) scans followed by complete physical and systemic examinations. RESULTS: The results of physical and systemic examinations were unremarkable for systemic lymphoma and a primary focus of cancer. The results of the ocular examination were normal. CT scans demonstrated well-defined lesions bilaterally with a homogeneous internal structure in the lacrimal gland fossa, which suggested a diagnosis of chronic dacryoadenitis. The differential diagnosis included lymphoma and orbital metastases. The patient refused a biopsy and was started on a tapering dose of 60 mg oral prednisolone daily. The follow-up CT scans 1 month after cessation of 6-week oral corticosteroid treatment showed near complete resolution of the orbital lesions. CONCLUSION: This case demonstrates that orbital inflammation can be misdiagnosed as refractory allergic conjunctivitis.