- Email: [email protected]
Comparison of Visual Field Defects in the Low-Tension Glaucomas With Those in the High-Tension Glaucomas
VOL. 98, NO. 6
CORRESPONDENCE
three- or four-muscle operation recently as a result of evolution of treatment, rather than using it throughout the tenyear span for a specific type of patient, then patients receiving that operation would have had a shorter mean followup. If patients with infantile esotropia tend to decompensate with time, possi bly the shorter follow-up enhanced their results. Also, patients that are doing well often drop out of treatment after many years. In the study by Hiles, Wat son, and Biglan, 2 an initial patient popu lation of 54 had fallen to 19 by the tenyear follow-up visit. If one chooses to use a "range" for follow-up, these prob lems can only be avoided by comparing patients in each group separately with similar lengths of follow-up. If we were to demand a ten-year follow-up for all patients treated for infantile esotropia, we would still not yet read reports of early experience with more than the standard 5-mm recession for the medial rectus muscle. At the time our article was written, the mean follow-up from surgery to last examination for our limbus group was 31 months. At that time, 68% (17 of 25) of our limbus group with more than 50 prism diopters of esotropia preoperatively had satisfactory alignment with one operation. We hope to report a long-term follow-up on this same group of patients. BURTON J. KUSHNER, M.D. G A I L V. M O R T O N , C O .
Madison,
Wisconsin
REFERENCES 1. Hirsch, C. E., and Scott, W. E.: Surgical treat ment of large angle congenital esotropia. ARVO Abstracts. Supplement to Invest. Ophthalmol. Vis. Sei. Philadelphia, J. B. Lippincott, 1984. p. 73. 2. Hiles, D. A., Watson, A., and Biglan, A. W.: Characteristics of infantile esotropia following early bimedial rectus recession. Arch. Ophthalmol. 98:697, 1980.
823
Comparison of Visual Field Defects in the Low-Tension Glaucomas With Those in the High-Tension Glaucomas EDITOR:
In their article, "Comparision of visu al field defects in the low-tension glau comas with those in the high-tension glaucomas," (Am. J. Ophthalmol., 97:730, June 1984), J. Caprioli and G. L. Spaeth presented evidence that visual field defects are close to fixation more frequently in low-tension glauco ma than in high-tension glaucoma. Other recent studies 1,2 have found no diiFerence between the two types of glauco ma in the distribution of visual field de fects (Table). Caprioli and Spaeth concluded that their results were more likely to be cor rect because their study used automated perimetry and the other two studies used manual perimetry. First, there may be differences be tween studies in patient selection crite ria. In our study 1 and that of Motolko, Drance, and Douglas, 2 all patients had typical nerve fiber bundle defects with deep cores in which a maximal luminos ity stimulus was not seen. Caprioli and Spaeth included shallower and broader defects, which in the other two studies may have been interpreted as nonspecif ic depression. Could this type of defect, away from fixation, be more common in high-tension glaucoma? Second, the method of perimetry they used was not appropriate for the ques tion they were asking. They used the Octopus Programs 31 or 32. These pro grams, which test with static threshold perimetry a grid of points 6 degrees apart, are excellent for describing the depth of a defect but poor for describing the spatial extent of a defect. The 6degree grid is too coarse. Nevertheless, Caprioli and Spaeth used these pro-
824
AMERICAN JOURNAL OF OPHTHALMOLOGY
DECEMBER, 1984
TABLE DEFECT CLOSE TO FIXATION
Study
Location of Defect
High-Tension Glaucoma
Low-Tension Glaucoma
Caprioloi and Spaeth Phelps, Hayreh, & Montague1 Motolko, Drance, & Douglas2
Within 6 degrees
66%
23%
Within 5 degrees
71%
63%
Within 5 degrees
81%
80%
grams to answer a spatial question: they wished to know the proximity of visual field defects to fixation. They also used the profile printout for their data analy sis. This printout is an interpolation, not a display of actual data points. A print out of a profile along the 90- to 270degree meridian, for example, if the data are collected with Program 32, will contain no loci that are actually tested. If one wants to answer spatial questions in perimetry, one should use kinetic perimetry, which is currently unavailable on any automated perimeter, or static perimetry with a grid of points much closer together than the 6-degree grid of Octopus Programs 31 and 32. We, too, think it is important to de termine if the distribution of visual field loss in the two conditions is similar or different because of possible implica tions regarding pathogenesis, but we urge that the results of the study of Caprioli and Spaeth be interpreted with caution. We believe the question is still open.
Fifth International Visual Field Symposium. The Hague, Dr. W. Junk Publishers, 1983, pp. 113-124. 2. Motolko, M., Drance, S. M., and Douglas, G. R. : The visual field defects of low-tension glauco ma. A comparison of the visual field defects in low-tension glaucoma with chronic open angle glaucoam. In Grève, E. L., and Heijl, A. (eds.): Fifth International Visual Field Symposium. The Hague, Dr. W. Junk Publishers, 1983, pp. 107-112.
Reply EDITOR:
We agree that it is important to de termine whether the distribution of vis ual field loss in low-tension glaucoma is fundamentally different from that hightension glaucoma. The studies 1,2 cited by Phelps, Hayreh, and Montague found no differ ence in the distribution of visual field loss in low-tension glaucomas vs hightension glaucomas. However, in addi tion to our findings, Primrose, 3 Levene, 4 Anderton and Hitchings, 5 and Grève and Geijssen 6 have detected significant differences between visual field loss in low-tension glaucomas and high-tension glaucomas. C H A R L E S D. P H E L P S , M.D. We did not state that our findings SOHAN S. H A Y R E H , M.D. were more likely to be correct simply PAUL R. MONTAGUE because we used an automated tech Iowa City, Iowa nique. We agree that our results differ from those of other studies 1,2 because of REFERENCES patient selection. We separated two 1. Phelps, C. D., Hayreh, S. S., and Montague, groups of patients by a wide margin of P. R. : Visual fields in low-tension glaucoma, primary open-angle glaucoma, and anterior ischémie optic intraocular pressure with the recorded neuropathy. In Grève, E. L. and Heijl, A. (eds.): intraocular pressure always 21 mm Hg
CORRESPONDENCE
three- or four-muscle operation recently as a result of evolution of treatment, rather than using it throughout the tenyear span for a specific type of patient, then patients receiving that operation would have had a shorter mean followup. If patients with infantile esotropia tend to decompensate with time, possi bly the shorter follow-up enhanced their results. Also, patients that are doing well often drop out of treatment after many years. In the study by Hiles, Wat son, and Biglan, 2 an initial patient popu lation of 54 had fallen to 19 by the tenyear follow-up visit. If one chooses to use a "range" for follow-up, these prob lems can only be avoided by comparing patients in each group separately with similar lengths of follow-up. If we were to demand a ten-year follow-up for all patients treated for infantile esotropia, we would still not yet read reports of early experience with more than the standard 5-mm recession for the medial rectus muscle. At the time our article was written, the mean follow-up from surgery to last examination for our limbus group was 31 months. At that time, 68% (17 of 25) of our limbus group with more than 50 prism diopters of esotropia preoperatively had satisfactory alignment with one operation. We hope to report a long-term follow-up on this same group of patients. BURTON J. KUSHNER, M.D. G A I L V. M O R T O N , C O .
Madison,
Wisconsin
REFERENCES 1. Hirsch, C. E., and Scott, W. E.: Surgical treat ment of large angle congenital esotropia. ARVO Abstracts. Supplement to Invest. Ophthalmol. Vis. Sei. Philadelphia, J. B. Lippincott, 1984. p. 73. 2. Hiles, D. A., Watson, A., and Biglan, A. W.: Characteristics of infantile esotropia following early bimedial rectus recession. Arch. Ophthalmol. 98:697, 1980.
823
Comparison of Visual Field Defects in the Low-Tension Glaucomas With Those in the High-Tension Glaucomas EDITOR:
In their article, "Comparision of visu al field defects in the low-tension glau comas with those in the high-tension glaucomas," (Am. J. Ophthalmol., 97:730, June 1984), J. Caprioli and G. L. Spaeth presented evidence that visual field defects are close to fixation more frequently in low-tension glauco ma than in high-tension glaucoma. Other recent studies 1,2 have found no diiFerence between the two types of glauco ma in the distribution of visual field de fects (Table). Caprioli and Spaeth concluded that their results were more likely to be cor rect because their study used automated perimetry and the other two studies used manual perimetry. First, there may be differences be tween studies in patient selection crite ria. In our study 1 and that of Motolko, Drance, and Douglas, 2 all patients had typical nerve fiber bundle defects with deep cores in which a maximal luminos ity stimulus was not seen. Caprioli and Spaeth included shallower and broader defects, which in the other two studies may have been interpreted as nonspecif ic depression. Could this type of defect, away from fixation, be more common in high-tension glaucoma? Second, the method of perimetry they used was not appropriate for the ques tion they were asking. They used the Octopus Programs 31 or 32. These pro grams, which test with static threshold perimetry a grid of points 6 degrees apart, are excellent for describing the depth of a defect but poor for describing the spatial extent of a defect. The 6degree grid is too coarse. Nevertheless, Caprioli and Spaeth used these pro-
824
AMERICAN JOURNAL OF OPHTHALMOLOGY
DECEMBER, 1984
TABLE DEFECT CLOSE TO FIXATION
Study
Location of Defect
High-Tension Glaucoma
Low-Tension Glaucoma
Caprioloi and Spaeth Phelps, Hayreh, & Montague1 Motolko, Drance, & Douglas2
Within 6 degrees
66%
23%
Within 5 degrees
71%
63%
Within 5 degrees
81%
80%
grams to answer a spatial question: they wished to know the proximity of visual field defects to fixation. They also used the profile printout for their data analy sis. This printout is an interpolation, not a display of actual data points. A print out of a profile along the 90- to 270degree meridian, for example, if the data are collected with Program 32, will contain no loci that are actually tested. If one wants to answer spatial questions in perimetry, one should use kinetic perimetry, which is currently unavailable on any automated perimeter, or static perimetry with a grid of points much closer together than the 6-degree grid of Octopus Programs 31 and 32. We, too, think it is important to de termine if the distribution of visual field loss in the two conditions is similar or different because of possible implica tions regarding pathogenesis, but we urge that the results of the study of Caprioli and Spaeth be interpreted with caution. We believe the question is still open.
Fifth International Visual Field Symposium. The Hague, Dr. W. Junk Publishers, 1983, pp. 113-124. 2. Motolko, M., Drance, S. M., and Douglas, G. R. : The visual field defects of low-tension glauco ma. A comparison of the visual field defects in low-tension glaucoma with chronic open angle glaucoam. In Grève, E. L., and Heijl, A. (eds.): Fifth International Visual Field Symposium. The Hague, Dr. W. Junk Publishers, 1983, pp. 107-112.
Reply EDITOR:
We agree that it is important to de termine whether the distribution of vis ual field loss in low-tension glaucoma is fundamentally different from that hightension glaucoma. The studies 1,2 cited by Phelps, Hayreh, and Montague found no differ ence in the distribution of visual field loss in low-tension glaucomas vs hightension glaucomas. However, in addi tion to our findings, Primrose, 3 Levene, 4 Anderton and Hitchings, 5 and Grève and Geijssen 6 have detected significant differences between visual field loss in low-tension glaucomas and high-tension glaucomas. C H A R L E S D. P H E L P S , M.D. We did not state that our findings SOHAN S. H A Y R E H , M.D. were more likely to be correct simply PAUL R. MONTAGUE because we used an automated tech Iowa City, Iowa nique. We agree that our results differ from those of other studies 1,2 because of REFERENCES patient selection. We separated two 1. Phelps, C. D., Hayreh, S. S., and Montague, groups of patients by a wide margin of P. R. : Visual fields in low-tension glaucoma, primary open-angle glaucoma, and anterior ischémie optic intraocular pressure with the recorded neuropathy. In Grève, E. L. and Heijl, A. (eds.): intraocular pressure always 21 mm Hg