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The natural course of ocular pressure in ocular hypertension
SURVEY
OF OPHTHALMOLOGY
The Natural
VOLUME 25
NUMBER 3
Course
Pressure in Ocular
ERIK LINNLR,
l
l
NOVEMBER-DECEMBER
1980
of Ocular Hypertension
M.D.
Department of Ophthalmology, Sahlgren’s
University Hospital, Giiteborg, Sweden
Abstract. The intraocular pressures of ocular hypertensives may undergo diurnal variation and/or slow cyclic variations over years. Studies of both types of variations are reviewed. Pressure tends to decrease cyclicly in some ocular hypertensives and to increase in others. It is possible that an increasing pressure trend may be an important symptom indicating a higher risk of development of glaucomatous damage. (Surv Opbthalmol 25: 136- 138, 1980)
cyclic variation ocular hypertension
Key words. l
0
l
diurnal variation
cular hypertension, as currently defined, is a condition in which the chamber angle is open and no characteristic glaucomatous lesions are found in the optic disc or in the visual field, but in which the intraocular pressure (IOP) is elevated above the normal range - in most studies above 20 or 21 mm Hg. The frequency of development of glaucomatous lesions in cases of ocular hypertension has been reported in many longterm studies. The risk seems to be not more than 5 to 10% and it increases with increasing pressure. 2*10There is, however, no simple relationship between IOP and the development of glaucomatous lesions. Factors other than pressure play an important role. The factors of susceptibility to the level of pressure are incompletely understood.12
l
intraocular pressure
pressure variations with time. This is partitularly true if we classify cases of ocular hypertension after one or only a few pressure Armaly’ studied the measurements. reliability of any single pressure reading with applanation tonometry, a method that has good accuracy. His analysis was performed on more than 1000 eyes measured yearly over a 5-year period, and he found that the variability was approximately 10%. DIURNAL
VARIATION
Phelps and coworkers* studied the diurnal variation of the IOP obtained from five measurements in 389 eyes of 204 individuals. From this sample a subsample of 89 eyes with an index pressure of 20-22 mm Hg was selected. The conclusion was that the peak IOP could best be predicted from a single office-hour measurement. About one-third in Variation in Intraocular Pressure this group reached a peak pressure above 25 There has been a tendency to discuss the mm Hg. Neither outflow facility nor corIOP in a particular eye as a more or less con- ticosteroid response provided significant additional predictive information. stant factor, without consideration of possible ‘136
NATURAL
COURSE OF IOP
Kitazawa and coworkers6 measured the IOP every hour for 24 hours in normal subjects, ocular hypertensives and primary open angle glaucoma patients.’ The mean diurnal variation was 8.4 mm Hg in the hypertensives as compared to 6.4 in the normal and 13.3 mm Hg in the glaucoma patients. The pressure measured at 11 AM or at noon showed a good correlation to the peak value. These values were therefore considered to be useful in predicting the peak of the diurnal curve. Armaly analyzed the effect of the time of the day during office hours on 1544 subjects.’ The pressure before noon was significantly higher than that in the afternoon, the mean difference being about 0.5 mm Hg. According to Leydhecker daily variations of more than 5 mm Hg or peaks over 25 mm Hg are usually symptoms of beginning glaucoma.s LONGTERM
CYCLIC
VARIATIONS
The main interest in many longterm studies of ocular hypertension was to investigate the development of glaucomatous damage. In some studies the changes of the IOP with time was analyzed in more detail. In the Bedford Glaucoma Survey, Perkins found 190 cases with IOP of 21 mm Hg or higher.’ These were considered to be borderline cases and they were examined annually. The IOP tended to be slightly lower at each annual examination. If the IOP remained below 21 mm Hg at two or more annual examinations, further followup was considered unnecessary and these individuals were discharged. The number of discharged cases was 102; an additional 58 subjects were lost to followup; and 30 individuals were followed for 5 to 7 years. Nine patients developed primary or secondary glaucoma. The natural course of pressure in the 132 subjects followed for two years or more showed a decreasing IOP in 77% and an IOP remaining above 21 mm Hg in 23%. Selected from a screening procedure of 2031 volunteer blood donors carried out by Norskov and coworkers,‘a 55 individuals with IOP of 20 mm Hg or higher in one or both eyes were followed. Thirty-nine of these subjects were followed for a period of 15 years without treatment. Twenty of these individuals (about 50%) showed a decreasing trend to a pressure level below 20 mm Hg and the remaining 19 demonstrated an unaltered
137
pressure. In 1960, Stromberg carried out a mass survey of ocular tension in 7275 individuals aged 40 years or more.” He used a Schiotz tonometer. A total of 325 individuals showing an initial tension higher than 20.6 mm Hg were then reexamined. During this procedure the number of individuals considered to have manifest ocular hypertension was reduced to 152 - about 2% of the population under examination. Complete data from 1961, 1965 and 1970 could not be obtained on all. In my followup study over a lo-year period, 92 ocular hypertensives remained. In the statistical analysis, the right eye only was used. The mean intraocular pressure decreased about 2 mm Hg from an initial value of 25 mm Hg. The mean outflow facility also decreased from an initial value of 0.24 to 0.20 pl/min/mm Hg. Each of these two changes may indicate a reduction in the rate of aqueous flow with time. Schwartz and coworkers recently carried out a study of spontaneous trends of pressure in ocular hypertension.” They followed 60 hypertensives, with a median period of followup of 42 months. Forty (67%) of these individuals did not show any significant changes in pressure with time. A decreasing trend was observed in 12 cases (20%). An increasing trend was found in 8 cases (13%). The authors concluded that the majority of ocular hypertensives are at the upper tail-end of the frequency distribution of pressure and that a pressure of 2 1 mm Hg or greater is normal for those individuals. According to the term used by Friedenwald,’ the pressure level in these cases represents the “normative” pressure for those eyes. Of the minority group of 8 individuals showing an increasing pressure trend, it was concluded that some of these patients may in time develop open angle glaucoma with visual field loss. Cyclic phenomena with a pattern covering one or two years were observed in 18 of 40 individuals without a significant pressure trend as well as in 4 of the 12 individuals showing a decreasing pressure trend. Clearly, such phenomena make the evaluation of the pressure still more difficult. In Armaly’s ten-year followup study,’ four patients developed visual field loss. Three of them showed an increasing pressure trend and one had an unchanged pressure of 23-24 mm Hg. In a longterm prospective study, Kitazawa
138
SW
Ophtholmol
25 (3) November-December
LINNER
1980
and coworkers followed 75 ocular hypertensives over at least 9 years.’ The pressure trends were not reported. In 8 eyes, visual field loss developed. The course of pressure was indicated in two of these eyes, and both of these curves showed a marked pressure increase at the time of the field loss.
Conclusions The pressures of some ocular hypertensive individuals change with time. There are diurnal variations and slow cyclic variations over years. The pressure tends to decrease in some ocular hypertensives and to increase in others. It is possible that an increasing pressure trend may be an important symptom indicating a higher risk of developing glaucomatous damage. Therefore, it is of clinical interest to recognize these cases as early as possible. Currently, we are unable to predict in which eyes such an increasing trend will occur.
References Armaly MF: Ocular pressure and visual fields. A ten-year follow-up study. Arch Ophthalmol 81:25-40, 1969 Armaly MF: Selective perimetry for glaucomatous defects in ocular hypertension. Arch Ophthalmol 87:5 18-524, 1972 Friedenwald JS: Symposium: Primary glaucoma. I.. Terminology, . . _ pathology and physiological mechanisms. Trans Am Acad Ophthalmol Otolaryngol 53:169, 1949 Kitazawa Y, Horie T, Aoki S, et al: Untreated ocular hypertension. A long-term prospective study. Arch Ophthalmol 95:1180-l 184, 1977
5. Kitazawa Y, Horie
T: Diurnal variation of intraocular pressure and its significance in the medical treatment of primary open-angle glaucoma, in Glaucoma Update. Berlin, Heidelberg, New York, Springer Verlag, 6 1979, pp 169-176 Leydhecker W: The intraocular pressure: Clinical aspects. Ann Ophthalmol 8:389-399, 1976 7. Linntr E: Ocular hypertension. I. The clinical course during ten years without therapy. Aqueous humour dynamics. Acta Ophthalmol 54:707-720, 1976 8. Perkins ES: The Bedford Glaucoma Survey. I. Long-term follow-up of borderline cases. Br J 9 Ophthalmol 57: 179- 185, I973 Phelps CD, Woolson RF, Kolker AE, Becker . B: Diurnal variation in intraocular pressure. Am J Ophthalmol 77:367-377, 1974 10. Pohjanpelto PEJ, Palva J: Ocular hypertension and glaucomatous optic nerve damage. Acta Ophthalmol 52: 194-200, 1974 11. Schwartz B, Talusan AG: Spontaneous trends of ocular pressure in untreated ocular hypertension. Arch Ophthalmol (in press) 12. Sears ML: Visual field loss in glaucoma. Am J Ophthalmol 88:492-498, 1979 13. SGrensen PN, Nielsen NV, Niirskov K: Ocular hypertension. A 15-year follow-up. Acta Ophthalmol 56:363-372, 1978 Acta 14. Strijmberg U: Ocular hypertension. Ophthalmol (Kbn) Soppl 69, I962
Reprint requests should be addressed to Erik Linnkr, M.D., Dept. of Ophthalmology, Sahlgren’s University Hospital, S-413 45, Gateborg, Sweden.
OF OPHTHALMOLOGY
The Natural
VOLUME 25
NUMBER 3
Course
Pressure in Ocular
ERIK LINNLR,
l
l
NOVEMBER-DECEMBER
1980
of Ocular Hypertension
M.D.
Department of Ophthalmology, Sahlgren’s
University Hospital, Giiteborg, Sweden
Abstract. The intraocular pressures of ocular hypertensives may undergo diurnal variation and/or slow cyclic variations over years. Studies of both types of variations are reviewed. Pressure tends to decrease cyclicly in some ocular hypertensives and to increase in others. It is possible that an increasing pressure trend may be an important symptom indicating a higher risk of development of glaucomatous damage. (Surv Opbthalmol 25: 136- 138, 1980)
cyclic variation ocular hypertension
Key words. l
0
l
diurnal variation
cular hypertension, as currently defined, is a condition in which the chamber angle is open and no characteristic glaucomatous lesions are found in the optic disc or in the visual field, but in which the intraocular pressure (IOP) is elevated above the normal range - in most studies above 20 or 21 mm Hg. The frequency of development of glaucomatous lesions in cases of ocular hypertension has been reported in many longterm studies. The risk seems to be not more than 5 to 10% and it increases with increasing pressure. 2*10There is, however, no simple relationship between IOP and the development of glaucomatous lesions. Factors other than pressure play an important role. The factors of susceptibility to the level of pressure are incompletely understood.12
l
intraocular pressure
pressure variations with time. This is partitularly true if we classify cases of ocular hypertension after one or only a few pressure Armaly’ studied the measurements. reliability of any single pressure reading with applanation tonometry, a method that has good accuracy. His analysis was performed on more than 1000 eyes measured yearly over a 5-year period, and he found that the variability was approximately 10%. DIURNAL
VARIATION
Phelps and coworkers* studied the diurnal variation of the IOP obtained from five measurements in 389 eyes of 204 individuals. From this sample a subsample of 89 eyes with an index pressure of 20-22 mm Hg was selected. The conclusion was that the peak IOP could best be predicted from a single office-hour measurement. About one-third in Variation in Intraocular Pressure this group reached a peak pressure above 25 There has been a tendency to discuss the mm Hg. Neither outflow facility nor corIOP in a particular eye as a more or less con- ticosteroid response provided significant additional predictive information. stant factor, without consideration of possible ‘136
NATURAL
COURSE OF IOP
Kitazawa and coworkers6 measured the IOP every hour for 24 hours in normal subjects, ocular hypertensives and primary open angle glaucoma patients.’ The mean diurnal variation was 8.4 mm Hg in the hypertensives as compared to 6.4 in the normal and 13.3 mm Hg in the glaucoma patients. The pressure measured at 11 AM or at noon showed a good correlation to the peak value. These values were therefore considered to be useful in predicting the peak of the diurnal curve. Armaly analyzed the effect of the time of the day during office hours on 1544 subjects.’ The pressure before noon was significantly higher than that in the afternoon, the mean difference being about 0.5 mm Hg. According to Leydhecker daily variations of more than 5 mm Hg or peaks over 25 mm Hg are usually symptoms of beginning glaucoma.s LONGTERM
CYCLIC
VARIATIONS
The main interest in many longterm studies of ocular hypertension was to investigate the development of glaucomatous damage. In some studies the changes of the IOP with time was analyzed in more detail. In the Bedford Glaucoma Survey, Perkins found 190 cases with IOP of 21 mm Hg or higher.’ These were considered to be borderline cases and they were examined annually. The IOP tended to be slightly lower at each annual examination. If the IOP remained below 21 mm Hg at two or more annual examinations, further followup was considered unnecessary and these individuals were discharged. The number of discharged cases was 102; an additional 58 subjects were lost to followup; and 30 individuals were followed for 5 to 7 years. Nine patients developed primary or secondary glaucoma. The natural course of pressure in the 132 subjects followed for two years or more showed a decreasing IOP in 77% and an IOP remaining above 21 mm Hg in 23%. Selected from a screening procedure of 2031 volunteer blood donors carried out by Norskov and coworkers,‘a 55 individuals with IOP of 20 mm Hg or higher in one or both eyes were followed. Thirty-nine of these subjects were followed for a period of 15 years without treatment. Twenty of these individuals (about 50%) showed a decreasing trend to a pressure level below 20 mm Hg and the remaining 19 demonstrated an unaltered
137
pressure. In 1960, Stromberg carried out a mass survey of ocular tension in 7275 individuals aged 40 years or more.” He used a Schiotz tonometer. A total of 325 individuals showing an initial tension higher than 20.6 mm Hg were then reexamined. During this procedure the number of individuals considered to have manifest ocular hypertension was reduced to 152 - about 2% of the population under examination. Complete data from 1961, 1965 and 1970 could not be obtained on all. In my followup study over a lo-year period, 92 ocular hypertensives remained. In the statistical analysis, the right eye only was used. The mean intraocular pressure decreased about 2 mm Hg from an initial value of 25 mm Hg. The mean outflow facility also decreased from an initial value of 0.24 to 0.20 pl/min/mm Hg. Each of these two changes may indicate a reduction in the rate of aqueous flow with time. Schwartz and coworkers recently carried out a study of spontaneous trends of pressure in ocular hypertension.” They followed 60 hypertensives, with a median period of followup of 42 months. Forty (67%) of these individuals did not show any significant changes in pressure with time. A decreasing trend was observed in 12 cases (20%). An increasing trend was found in 8 cases (13%). The authors concluded that the majority of ocular hypertensives are at the upper tail-end of the frequency distribution of pressure and that a pressure of 2 1 mm Hg or greater is normal for those individuals. According to the term used by Friedenwald,’ the pressure level in these cases represents the “normative” pressure for those eyes. Of the minority group of 8 individuals showing an increasing pressure trend, it was concluded that some of these patients may in time develop open angle glaucoma with visual field loss. Cyclic phenomena with a pattern covering one or two years were observed in 18 of 40 individuals without a significant pressure trend as well as in 4 of the 12 individuals showing a decreasing pressure trend. Clearly, such phenomena make the evaluation of the pressure still more difficult. In Armaly’s ten-year followup study,’ four patients developed visual field loss. Three of them showed an increasing pressure trend and one had an unchanged pressure of 23-24 mm Hg. In a longterm prospective study, Kitazawa
138
SW
Ophtholmol
25 (3) November-December
LINNER
1980
and coworkers followed 75 ocular hypertensives over at least 9 years.’ The pressure trends were not reported. In 8 eyes, visual field loss developed. The course of pressure was indicated in two of these eyes, and both of these curves showed a marked pressure increase at the time of the field loss.
Conclusions The pressures of some ocular hypertensive individuals change with time. There are diurnal variations and slow cyclic variations over years. The pressure tends to decrease in some ocular hypertensives and to increase in others. It is possible that an increasing pressure trend may be an important symptom indicating a higher risk of developing glaucomatous damage. Therefore, it is of clinical interest to recognize these cases as early as possible. Currently, we are unable to predict in which eyes such an increasing trend will occur.
References Armaly MF: Ocular pressure and visual fields. A ten-year follow-up study. Arch Ophthalmol 81:25-40, 1969 Armaly MF: Selective perimetry for glaucomatous defects in ocular hypertension. Arch Ophthalmol 87:5 18-524, 1972 Friedenwald JS: Symposium: Primary glaucoma. I.. Terminology, . . _ pathology and physiological mechanisms. Trans Am Acad Ophthalmol Otolaryngol 53:169, 1949 Kitazawa Y, Horie T, Aoki S, et al: Untreated ocular hypertension. A long-term prospective study. Arch Ophthalmol 95:1180-l 184, 1977
5. Kitazawa Y, Horie
T: Diurnal variation of intraocular pressure and its significance in the medical treatment of primary open-angle glaucoma, in Glaucoma Update. Berlin, Heidelberg, New York, Springer Verlag, 6 1979, pp 169-176 Leydhecker W: The intraocular pressure: Clinical aspects. Ann Ophthalmol 8:389-399, 1976 7. Linntr E: Ocular hypertension. I. The clinical course during ten years without therapy. Aqueous humour dynamics. Acta Ophthalmol 54:707-720, 1976 8. Perkins ES: The Bedford Glaucoma Survey. I. Long-term follow-up of borderline cases. Br J 9 Ophthalmol 57: 179- 185, I973 Phelps CD, Woolson RF, Kolker AE, Becker . B: Diurnal variation in intraocular pressure. Am J Ophthalmol 77:367-377, 1974 10. Pohjanpelto PEJ, Palva J: Ocular hypertension and glaucomatous optic nerve damage. Acta Ophthalmol 52: 194-200, 1974 11. Schwartz B, Talusan AG: Spontaneous trends of ocular pressure in untreated ocular hypertension. Arch Ophthalmol (in press) 12. Sears ML: Visual field loss in glaucoma. Am J Ophthalmol 88:492-498, 1979 13. SGrensen PN, Nielsen NV, Niirskov K: Ocular hypertension. A 15-year follow-up. Acta Ophthalmol 56:363-372, 1978 Acta 14. Strijmberg U: Ocular hypertension. Ophthalmol (Kbn) Soppl 69, I962
Reprint requests should be addressed to Erik Linnkr, M.D., Dept. of Ophthalmology, Sahlgren’s University Hospital, S-413 45, Gateborg, Sweden.