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Re: Baskaran et al.: Anterior segment imaging predicts incident gonioscopic angle closure (Ophthalmology 2015;122:2380-2)
Correspondence the optical coherence tomography test. It is surprising that only 53% of patients had changes in optical coherence tomography that predicted field loss. The study does not answer the question of whether changes in disk photos can be as good a predictor of field defects as optical coherence tomography.
LAWRENCE E. WEENE, MD Solo Practitioner, Ophthalmologist, Brockton, Massachusetts Financial Disclosures: The author has no proprietary or commercial interest in any materials discussed in this article. The authors of the original article declined to reply. Correspondence: Lawrence E. Weene, MD, Solo Practitioner, Ophthalmologist, 59 North Pearl Street, Brockton, MA 02301. E-mail: [email protected].
Reference 1. Kuang TM, Zhang C, Zangwill LM, et al. Estimating lead time gained by optical coherence topography in detecting glaucoma before development of visual field defects. Ophthalmology 2015;122:2002–9.
Re: Baskaran et al.: Anterior segment imaging predicts incident gonioscopic angle closure
of the anterior chamber angle images obtained with the Visante AS-OCT. This impacts on the analysis of the anterior chamber angle and assessment for angle closure on OCT. Anterior lens vault measurements would have provided additional value in the use of AS-OCT to predict incident gonioscopic angle closure because they quantify the amount of the lens that is located anterior to the anterior chamber angles and has been found to be independently associated with angle closure. The analysis was based on the number of subjects, not eyes with closed angles classified by the presence of 2 closed angle quadrants in either eye. Using number of eyes in place of subjects may have brought further clarity to the numbers and analysis. Finally, there may have been an element of follow-up bias in that those more likely to agree to follow-up may come from a symptomatic population. In light of these issues, it is difficult to comment conclusively on the use of AS-OCT to predict the incident of gonioscopic angle closure.
BANSRI K. LAKHANI, MBCHB PAVI AGRAWAL, MB BCHIR, FRCOPHTH Nottingham, United Kingdom Financial Disclosures: The authors have no proprietary or commercial interest in any materials discussed in this article. Correspondence: Bansri K. Lakhani, MBChB, Department of Ophthalmology, Nottingham, United Kingdom. E-mail: [email protected].
(Ophthalmology 2015;122:2380-2) We read with interest the article by Baskaran et al,1 in which the authors found that angle closure on anterior segment (AS) optical coherence tomography (OCT) predicts gonioscopic angle closure in patients with gonioscopically open angles at baseline. However, we raise the following questions with regard to their methodology. Blunt trauma to the eye is well-recognized to cause anterior chamber angle recession, yet was not part of the study’s exclusion criteria.2 With regard to gonioscopy, 2 different masked examiners were used at 0 and 4 years; however, there is no mention of the intertest and intratest variability testing between the 2 examiners, which may have identified observer disagreements. Imaging with Visante AS-OCT scans was carried out along 2 planes3; the horizontal (nasaletemporal angles at 0 e180 ) and vertical meridians (superioreinferior angles 90 e270 ). Static images at these points do not necessarily represent angle closure of that quadrant because the angle may be wider or narrower on either side of the measured point. Static point analysis does not provide adequate assessment of the 360 angle when defining angle closure within a quadrant. A more accurate way would be to undertake analysis of the whole quadrant using 360 assessment and identifying the percentage of iridotrabecular contact present within that quadrant, with a minimum quota being set, for example, at 50% for it to be clinically significant of angle closure. The identification of the scleral spur as a key reference landmark when assessing anterior chamber parameters and eyes at risk of closure is problematic. Aung et al4 have previously reported that scleral spur location could not be detected in approximately 30% TO THE EDITOR:
References 1. Baskaran M, Iyer JV, Narayanaswamy AK, et al. Anterior segment imaging predicts incident gonioscopic angle closure. Ophthalmology 2015;122:2380–2. 2. Canavan YM, Archer DB. Anterior segment consequences of blunt ocular injury. Br J Ophthalmol 1982;66:549–53. 3. Lavanya R, Foster PJ, Sakata LM, et al. Screening for narrow angles in the Singapore population: evaluation of new noncontact screening methods. Ophthalmology 2008;115: 1720–2. 4. Sakata LM, Lavanya R, Friedman DS, et al. Assessment of the scleral spur in anterior segment optical coherence tomography images. Arch Ophthalmol 2008;126:181–4. We thank Lakhani et al for their interest in our study.1 We agree that blunt trauma should have been one of the exclusion criteria. However, none of the subjects included had a history of blunt trauma in the past or during the interim period of follow-up, nor had angle recession on gonioscopy. We agree with the authors regarding the importance of intertest reliability for grading gonioscopic angle closure by different observers. We have mentioned this point as a limitation of the study in the discussion. We have documented the agreement for documenting gonioscopic angle closure between the study gonioscopist and a senior ophthalmologist in the original study. A weighted kappa of 0.82 was achieved for this assessment.2 We also agree with the authors’ comments regarding the disadvantages of static point analysis compared to 360 assessment for grading angle REPLY:
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LAWRENCE E. WEENE, MD Solo Practitioner, Ophthalmologist, Brockton, Massachusetts Financial Disclosures: The author has no proprietary or commercial interest in any materials discussed in this article. The authors of the original article declined to reply. Correspondence: Lawrence E. Weene, MD, Solo Practitioner, Ophthalmologist, 59 North Pearl Street, Brockton, MA 02301. E-mail: [email protected].
Reference 1. Kuang TM, Zhang C, Zangwill LM, et al. Estimating lead time gained by optical coherence topography in detecting glaucoma before development of visual field defects. Ophthalmology 2015;122:2002–9.
Re: Baskaran et al.: Anterior segment imaging predicts incident gonioscopic angle closure
of the anterior chamber angle images obtained with the Visante AS-OCT. This impacts on the analysis of the anterior chamber angle and assessment for angle closure on OCT. Anterior lens vault measurements would have provided additional value in the use of AS-OCT to predict incident gonioscopic angle closure because they quantify the amount of the lens that is located anterior to the anterior chamber angles and has been found to be independently associated with angle closure. The analysis was based on the number of subjects, not eyes with closed angles classified by the presence of 2 closed angle quadrants in either eye. Using number of eyes in place of subjects may have brought further clarity to the numbers and analysis. Finally, there may have been an element of follow-up bias in that those more likely to agree to follow-up may come from a symptomatic population. In light of these issues, it is difficult to comment conclusively on the use of AS-OCT to predict the incident of gonioscopic angle closure.
BANSRI K. LAKHANI, MBCHB PAVI AGRAWAL, MB BCHIR, FRCOPHTH Nottingham, United Kingdom Financial Disclosures: The authors have no proprietary or commercial interest in any materials discussed in this article. Correspondence: Bansri K. Lakhani, MBChB, Department of Ophthalmology, Nottingham, United Kingdom. E-mail: [email protected].
(Ophthalmology 2015;122:2380-2) We read with interest the article by Baskaran et al,1 in which the authors found that angle closure on anterior segment (AS) optical coherence tomography (OCT) predicts gonioscopic angle closure in patients with gonioscopically open angles at baseline. However, we raise the following questions with regard to their methodology. Blunt trauma to the eye is well-recognized to cause anterior chamber angle recession, yet was not part of the study’s exclusion criteria.2 With regard to gonioscopy, 2 different masked examiners were used at 0 and 4 years; however, there is no mention of the intertest and intratest variability testing between the 2 examiners, which may have identified observer disagreements. Imaging with Visante AS-OCT scans was carried out along 2 planes3; the horizontal (nasaletemporal angles at 0 e180 ) and vertical meridians (superioreinferior angles 90 e270 ). Static images at these points do not necessarily represent angle closure of that quadrant because the angle may be wider or narrower on either side of the measured point. Static point analysis does not provide adequate assessment of the 360 angle when defining angle closure within a quadrant. A more accurate way would be to undertake analysis of the whole quadrant using 360 assessment and identifying the percentage of iridotrabecular contact present within that quadrant, with a minimum quota being set, for example, at 50% for it to be clinically significant of angle closure. The identification of the scleral spur as a key reference landmark when assessing anterior chamber parameters and eyes at risk of closure is problematic. Aung et al4 have previously reported that scleral spur location could not be detected in approximately 30% TO THE EDITOR:
References 1. Baskaran M, Iyer JV, Narayanaswamy AK, et al. Anterior segment imaging predicts incident gonioscopic angle closure. Ophthalmology 2015;122:2380–2. 2. Canavan YM, Archer DB. Anterior segment consequences of blunt ocular injury. Br J Ophthalmol 1982;66:549–53. 3. Lavanya R, Foster PJ, Sakata LM, et al. Screening for narrow angles in the Singapore population: evaluation of new noncontact screening methods. Ophthalmology 2008;115: 1720–2. 4. Sakata LM, Lavanya R, Friedman DS, et al. Assessment of the scleral spur in anterior segment optical coherence tomography images. Arch Ophthalmol 2008;126:181–4. We thank Lakhani et al for their interest in our study.1 We agree that blunt trauma should have been one of the exclusion criteria. However, none of the subjects included had a history of blunt trauma in the past or during the interim period of follow-up, nor had angle recession on gonioscopy. We agree with the authors regarding the importance of intertest reliability for grading gonioscopic angle closure by different observers. We have mentioned this point as a limitation of the study in the discussion. We have documented the agreement for documenting gonioscopic angle closure between the study gonioscopist and a senior ophthalmologist in the original study. A weighted kappa of 0.82 was achieved for this assessment.2 We also agree with the authors’ comments regarding the disadvantages of static point analysis compared to 360 assessment for grading angle REPLY:
e53