ORIGINAL STUDY
Ocular Biometrics of Myopic Eyes With Narrow Angles Gabriel T. Chong, MD,* Joanne C. Wen, MD,* Daniel Hsien-Wen Su, MD,*w Sandra Stinnett, PhD,* and Sanjay Asrani, MD*
Purpose: The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Methods: Patients with a stable myopic refraction (myopia worse than 1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. Results: A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P = 0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P = 0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P = 0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P = 0.32, 0.47, 0.15). Conclusions: Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error. Key Words: myopia, narrow angle, optical coherence tomography, primary angle closure
(J Glaucoma 2016;25:140–144)
P
rimary angle closure glaucoma (PACG) is a common form of glaucoma worldwide accounting for approximately half of the world’s glaucoma-related blindness.1 Eyes with narrow angles, where the iris and trabecular meshwork are in close proximity, are thought to be at risk for acute angle closure. Numerous studies have found that eyes with PACG tend to be hyperopic and have a shallow central anterior chamber depth (ACD), a thicker crystalline lens, a smaller corneal diameter and radius of curvature, and a shorter axial length.2–5 Because of these findings, it was often assumed that myopic eyes, with their longer axial lengths and ACDs,6,7 were unlikely to have narrow angles and be at risk for PACG. Routine gonioscopy in these patients is often deferred given these assumptions. However, recent studies report that despite these general findings, there are cases of angle closure in myopic eyes and Received for publication August 15, 2013; accepted August 21, 2014. From the *Department of Ophthalmology, Duke University Eye Center, Durham, NC; and wSingapore National Eye Centre, Singapore, Singapore. Disclosure: The authors declare no conflict of interest. Reprints: Sanjay Asrani, MD, Duke Eye Center, 2351 Erwin Road DUMC 3802, Durham 27710, NC (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000130
even in highly myopic eyes.8–10 In our glaucoma clinic, we have noted a number of myopic eyes with narrow angles on gonioscopy and were interested in better characterizing these findings. The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles using anterior segment optical coherence tomography (AS-OCT) (Visante OCT 3.0; Carl Zeiss Meditec. Dublin, CA) and an IOLMaster (Carl Zeiss Meditec, Jena, Germany).
METHODS This study was approved by the institutional review board of Duke University and informed consent was obtained from all patients. In this prospective case-controlled study, consecutive subjects aged above 18 years with myopia (defined as myopia worse than a spherical equivalent of 1.00 D with stable refractive error for the past 5 y by history) were recruited from a glaucoma specialty clinic. Exclusion criteria included asymmetric gonioscopic findings, prior intraocular surgery or penetrating eye injury, and prior laser procedures. Patient information including age, sex, ethnicity, and refractive error were obtained from the clinical chart. All patients underwent a detailed eye examination including gonioscopy and biometric measurements using an AS-OCT and an IOLMaster. Gonioscopy was performed by a single ophthalmologist with subspecialty glaucoma training (S.A.). Gonioscopy was performed in a darkened room using a 4-mirror lens with a narrow slit beam with care taken to avoid light falling on the pupil. An angle was considered narrow if there was
Ocular Biometrics of Myopic Eyes With Narrow Angles Gabriel T. Chong, MD,* Joanne C. Wen, MD,* Daniel Hsien-Wen Su, MD,*w Sandra Stinnett, PhD,* and Sanjay Asrani, MD*
Purpose: The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles. Methods: Patients with a stable myopic refraction (myopia worse than 1.00 D spherical equivalent) were prospectively recruited. Angle status was assessed using gonioscopy and biometric measurements were performed using an anterior segment optical coherence tomography and an IOLMaster. Results: A total of 29 patients (58 eyes) were enrolled with 13 patients (26 eyes) classified as having narrow angles and 16 patients (32 eyes) classified as having open angles. Baseline demographics of age, sex, and ethnicity did not differ significantly between the 2 groups. The patients with narrow angles were on average older than those with open angles but the difference did not reach statistical significance (P = 0.12). The central anterior chamber depth was significantly less in the eyes with narrow angles (P = 0.05). However, the average lens thickness, although greater in the eyes with narrow angles, did not reach statistical significance (P = 0.10). Refractive error, axial lengths, and iris thicknesses did not differ significantly between the 2 groups (P = 0.32, 0.47, 0.15). Conclusions: Narrow angles can occur in myopic eyes. Routine gonioscopy is therefore recommended for all patients regardless of refractive error. Key Words: myopia, narrow angle, optical coherence tomography, primary angle closure
(J Glaucoma 2016;25:140–144)
P
rimary angle closure glaucoma (PACG) is a common form of glaucoma worldwide accounting for approximately half of the world’s glaucoma-related blindness.1 Eyes with narrow angles, where the iris and trabecular meshwork are in close proximity, are thought to be at risk for acute angle closure. Numerous studies have found that eyes with PACG tend to be hyperopic and have a shallow central anterior chamber depth (ACD), a thicker crystalline lens, a smaller corneal diameter and radius of curvature, and a shorter axial length.2–5 Because of these findings, it was often assumed that myopic eyes, with their longer axial lengths and ACDs,6,7 were unlikely to have narrow angles and be at risk for PACG. Routine gonioscopy in these patients is often deferred given these assumptions. However, recent studies report that despite these general findings, there are cases of angle closure in myopic eyes and Received for publication August 15, 2013; accepted August 21, 2014. From the *Department of Ophthalmology, Duke University Eye Center, Durham, NC; and wSingapore National Eye Centre, Singapore, Singapore. Disclosure: The authors declare no conflict of interest. Reprints: Sanjay Asrani, MD, Duke Eye Center, 2351 Erwin Road DUMC 3802, Durham 27710, NC (e-mail: [email protected]). Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/IJG.0000000000000130
even in highly myopic eyes.8–10 In our glaucoma clinic, we have noted a number of myopic eyes with narrow angles on gonioscopy and were interested in better characterizing these findings. The purpose of this study was to compare the ocular biometrics between myopic patients with and without narrow angles using anterior segment optical coherence tomography (AS-OCT) (Visante OCT 3.0; Carl Zeiss Meditec. Dublin, CA) and an IOLMaster (Carl Zeiss Meditec, Jena, Germany).
METHODS This study was approved by the institutional review board of Duke University and informed consent was obtained from all patients. In this prospective case-controlled study, consecutive subjects aged above 18 years with myopia (defined as myopia worse than a spherical equivalent of 1.00 D with stable refractive error for the past 5 y by history) were recruited from a glaucoma specialty clinic. Exclusion criteria included asymmetric gonioscopic findings, prior intraocular surgery or penetrating eye injury, and prior laser procedures. Patient information including age, sex, ethnicity, and refractive error were obtained from the clinical chart. All patients underwent a detailed eye examination including gonioscopy and biometric measurements using an AS-OCT and an IOLMaster. Gonioscopy was performed by a single ophthalmologist with subspecialty glaucoma training (S.A.). Gonioscopy was performed in a darkened room using a 4-mirror lens with a narrow slit beam with care taken to avoid light falling on the pupil. An angle was considered narrow if there was
