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Phacoemulsification and Glaucoma
Letters to the Editor do agree completely with Dr. Nazm et al that our readers must interpret the findings in the light of those limitations. CLEMENT C.Y. THAM, FRCS YOLANDA Y.Y. KWONG, MRCS DEXTER Y.L. LEUNG, FRCS S.W. LAM, MRCS FELIX C.H. LI, MRCS THOMAS Y.H. CHIU, FRCS JONATHAN C.H. CHAN, FRCS DENNIS S.C. LAM, FRCS, FRCOPHTH JIMMY S.M. LAI, MD, FRCOPHTH Hong Kong, China References 1. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology 2009;116:725–31, 731. 2. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically controlled chronic angle closure glaucoma with cataract. Ophthalmology 2008;115:2167–73.
Phacoemulsification and Glaucoma Dear Editor: We read with interest the article by Tham et al1 that described a randomized clinical trial for angle closure glaucoma management. The study suggested that phacoemulsification alone, as opposed to combined phacotrabeculectomy, could be an effective approach in the management of patients with medically uncontrolled chronic angle closure glaucoma (CACG) and coexistent cataract. Phacoemulsification alone would avoid trabeculecotmy complications and be less damaging on quality of life than the combined procedure. There are, however, a few issues in the paper that we would like to clarify and bring to the attention of the readers. The authors did not stratify the subjects based on the level of severity of preoperative glaucomatous visual field loss. Stratification would have enabled better interpretation of the results and helped one determine whether a phacoemulsification procedure alone would be sufficient in the management of patients with more severe glaucomatous visual field loss. We fear that there may be a risk of intraocular pressure (IOP) spike, or IOP fluctuations that may be detrimental to the already compromised optic nerve in such patients. In addition, the postoperative IOP in the 2 groups was compared regardless of whether IOP-lowering medications were used. It would have been of interest to compare the IOP ranges that followed either procedure before IOPlowering medicines were started to establish the efficacy of these procedures. It was also mentioned that 4 of the 24 patients in the phacoemulsification group required subsequent trabeculectomy. It is unclear from the paper whether these patients were included in the comparison of data between the 2 groups for the defined primary outcome measures such as IOP. They should have been excluded
since they have now undergone trabeculectomy and be classified as failures. We understand that masking the observers would be difficult given the apparent nature of the operation. As such, objective quantification using tools such as Heidelberg Retina Tomography, optical coherence tomography, or other imaging methods accurately to monitor the cup-disc ratio and retinal nerve fiber layer thickness would have given a more objective and clearer picture of progression of glaucomatous optic neuropathy, as opposed to the subjective measures mentioned in the study–appearance of a new splinter hemorrhage, appearance of a new or extension of old neuroretinal rim notching, appearance of new or extension of old retinal nerve fiber layer defects and increase of vertical cup-disc ratio ⬎0.1 noted at 2 or more clinical visits. In summary, we would like to congratulate the authors on publishing this eagerly awaited study and look forward to other publications from this trial. However, we believe that further information such as stratification of glaucoma severity as suggested, more objective measures of progression and a longer follow-up period, are warranted before any conclusions should be drawn as to whether phacoemulsification alone is adequate for the management of patients with medically uncontrolled CACG and concurrent cataract. JAYANT V. IYER, MBBS SHAMIRA A. PERERA, FRCOPHTH TIN AUNG, PHD, FRCOPHTH Singapore, Singapore Reference 1. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology 2009;116:725–31.
Author reply Dear Editor: We are grateful to Dr. Iyer et al for their interest in our article,1 and for allowing us the opportunity to clarify and further elaborate on these important issues. If we analyze only the more advanced chronic angle closure glaucoma (CACG) eyes (preoperative pattern standard deviation [PSD] greater than the median PSD of 4.13 decibels), there was no statistically significant difference between the 2 treatment groups in the proportion of cases with visual field progression (P⫽0.94, chi-square test). Phacoemulsification alone did not appear to result in a greater risk of visual field progression than combined phacotrabeculectomy amongst the more advanced CACG cases. In our study design, we did not stop all the glaucoma medications immediately after phacoemulsification. We used the more conservative, and possibly safer, approach of stopping the medications one by one in this group during subsequent follow up. We therefore did not have the intraocular pressure (IOP) data without medications for all phacoemulsification patients. However, looking at the IOP and the drug data side by side would allow us a good idea
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Phacoemulsification and Glaucoma Dear Editor: We read with interest the article by Tham et al1 that described a randomized clinical trial for angle closure glaucoma management. The study suggested that phacoemulsification alone, as opposed to combined phacotrabeculectomy, could be an effective approach in the management of patients with medically uncontrolled chronic angle closure glaucoma (CACG) and coexistent cataract. Phacoemulsification alone would avoid trabeculecotmy complications and be less damaging on quality of life than the combined procedure. There are, however, a few issues in the paper that we would like to clarify and bring to the attention of the readers. The authors did not stratify the subjects based on the level of severity of preoperative glaucomatous visual field loss. Stratification would have enabled better interpretation of the results and helped one determine whether a phacoemulsification procedure alone would be sufficient in the management of patients with more severe glaucomatous visual field loss. We fear that there may be a risk of intraocular pressure (IOP) spike, or IOP fluctuations that may be detrimental to the already compromised optic nerve in such patients. In addition, the postoperative IOP in the 2 groups was compared regardless of whether IOP-lowering medications were used. It would have been of interest to compare the IOP ranges that followed either procedure before IOPlowering medicines were started to establish the efficacy of these procedures. It was also mentioned that 4 of the 24 patients in the phacoemulsification group required subsequent trabeculectomy. It is unclear from the paper whether these patients were included in the comparison of data between the 2 groups for the defined primary outcome measures such as IOP. They should have been excluded
since they have now undergone trabeculectomy and be classified as failures. We understand that masking the observers would be difficult given the apparent nature of the operation. As such, objective quantification using tools such as Heidelberg Retina Tomography, optical coherence tomography, or other imaging methods accurately to monitor the cup-disc ratio and retinal nerve fiber layer thickness would have given a more objective and clearer picture of progression of glaucomatous optic neuropathy, as opposed to the subjective measures mentioned in the study–appearance of a new splinter hemorrhage, appearance of a new or extension of old neuroretinal rim notching, appearance of new or extension of old retinal nerve fiber layer defects and increase of vertical cup-disc ratio ⬎0.1 noted at 2 or more clinical visits. In summary, we would like to congratulate the authors on publishing this eagerly awaited study and look forward to other publications from this trial. However, we believe that further information such as stratification of glaucoma severity as suggested, more objective measures of progression and a longer follow-up period, are warranted before any conclusions should be drawn as to whether phacoemulsification alone is adequate for the management of patients with medically uncontrolled CACG and concurrent cataract. JAYANT V. IYER, MBBS SHAMIRA A. PERERA, FRCOPHTH TIN AUNG, PHD, FRCOPHTH Singapore, Singapore Reference 1. Tham CC, Kwong YY, Leung DY, et al. Phacoemulsification versus combined phacotrabeculectomy in medically uncontrolled chronic angle closure glaucoma with cataracts. Ophthalmology 2009;116:725–31.
Author reply Dear Editor: We are grateful to Dr. Iyer et al for their interest in our article,1 and for allowing us the opportunity to clarify and further elaborate on these important issues. If we analyze only the more advanced chronic angle closure glaucoma (CACG) eyes (preoperative pattern standard deviation [PSD] greater than the median PSD of 4.13 decibels), there was no statistically significant difference between the 2 treatment groups in the proportion of cases with visual field progression (P⫽0.94, chi-square test). Phacoemulsification alone did not appear to result in a greater risk of visual field progression than combined phacotrabeculectomy amongst the more advanced CACG cases. In our study design, we did not stop all the glaucoma medications immediately after phacoemulsification. We used the more conservative, and possibly safer, approach of stopping the medications one by one in this group during subsequent follow up. We therefore did not have the intraocular pressure (IOP) data without medications for all phacoemulsification patients. However, looking at the IOP and the drug data side by side would allow us a good idea
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