|Year : 1964 | Volume
| Issue : 4 | Page : 169-172
Bulbar pressure test in chronic simple glaucoma
OP Ahuja, RT Singh
Department of Ophthalmology, G.S.V.M. Medical College, Kanpur, U.P, India
|Date of Web Publication||13-Feb-2008|
O P Ahuja
Department of Ophthalmology, G.S.V.M. Medical College, Kanpur, U.P
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Ahuja O P, Singh R T. Bulbar pressure test in chronic simple glaucoma. Indian J Ophthalmol 1964;12:169-72
By experience, it is fully realised that tonometry alone is not sufficient to rule out glaucoma in its early stages. When tonometry alone is employed as the criterion of diagnosis it is expected to show a lower incidence of glaucoma. because the ocular hypertension in early cases of glaucoma is only intermittent and the patient may present himself for examination at a time when his ocular tension is normal.
To reduce the incidence of false negatives, the principle of Bulbar massage or compression has been extensively studied. This has resulted in the development of clinical tonography. Tonography is one instance of the massage test which gives satisfactory clinical results and is being widely used in clinical practice. This, however, demands an elaborate and expensive apparatus and elaborate calculations. Because of these factors there are only few centres in our country which have been equipped with the apparatus. Moreover, most workers in tonography agree that this is and should be a laboratory test in skilled hands. In view of these factors tonography cannot be regarded as a routine and screening investigation especially in our country.
Blaxter (1953), exploited the principle of Bulbar massage and introduced his Bulbar Pressure test. He claimed to have obtained very satisfactory results and advocated the use of this test as a tool in the early diagnosis of glaucoma. The test is simple to perform and requires simple, handy and easily portable instruments. Under the circumstances, the test appears to be well suited for our purpose. Keeping in view the simplicity of the procedure and its suitability as a screening measure, an attempt was made to evaluate Bulbar Pressure test in chronic simple glaucoma.
Principle of the Bulbar Pressure Test
The principle of this test depends upon the fact that if an eye is compressed and change in intraocular pressure recorded at the same time, information is obtained, from while a figure can be calculated which is directly dependent on the change of aqueous volume. The figure has been termed as 'Outflow fraction' (O.F.).
| Method|| |
The eye is anaesthetised with Anethaine (1%) drops and a drop of parolein is instilled in the conjunctival sac to prevent corneal damage. The patient lies on a couch and fixes, with the eye opposite the one to be tested, an object suspended straight above.
To perform the test on a right eye, the tonometer is applied to the centre of cornea with the left hand and the first reading (A) is taken. The Bailliart dynamometer is held in the right hand and its foot plate applied on the lateral aspect of the globe behind the insertion of lateral rectus muscle. A pressure of 50 gm is applied and after allowing 5-10 seconds for intraocular tension to stabilise, the reading (B) is taken. This position is maintained for 4 minutes at the end of which the reading (C) is taken. Then the dynamometer is removed to give the reading (D).
The outflow fraction (O.F.) is calculated by taking the fall in tension in terms of percentage of the initial tension i.e..
[Figure - 1] indicates the diagrammatic representation of the test.
| Present Study|| |
The present study was carried out in 40 eyes (normal-20: chronic simple glaucoma-20).
Normal eyes were selected from the patients attending the out patients department or admitted in the indoor section of the department of ophthalmology G.S.V.M. Medical College, Kanpur, for various diseases like trachoma. corneal opacity, refractive errors and others. In these cases the presence of glaucoma was carefully excluded.
The cases of established chronic simple glaucoma were collected from the ophthalmic wards of G.S.V.M. Medical College, hospitals.
O.F. value was determined in the normal eyes and an average was established as standard control.
In glaucomatous eyes, the O.F., value was calculated before institution of any treatment and again after 48 hours of miotic therapy and after operation, when the eye was suitable for the test.
Miotic therapy in these cases consisted of pilocarpine 2% drops, 6 times a day for 48 hours. The operative procedure adopted was corneo-scleral trepanation with a 1.5 mm trephine.
| Results|| |
O.F. values as found in the normal eyes were as follows see [Table - 1].
The O.F. values in normal eyes varied from 30.0 to 39.2%. The average figure was calculated to be 33.98% or 34%.
O.F. was calculated in cases of chronic simple glaucoma before starting the treatment and again after 48 hours of miotic treatment and finally after operation. Following results were obtained see [Table - 2].
Before treatment varied from 11.6---
25.0% (average value=16.9%)
After miotic treatment --- Varied from 13.0--39.2% (average 26.0%).
After operation varied from-39.2-58.8% (average-50.5%).
| Discussion|| |
In the present study, it was found that the lowest OF. value in normal cases was 30% and the highest O.F. value in cases of chronic simple glaucoma was 25%. It is clear, therefore, that O.F. value in all cases of chronic simple glaucoma is below the lower normal limit. Putting it in other words it may safely be suggested that O.F. values as calculated by B.P. Test can be relied upon as a diagnostic test in cases of chronic simple glaucoma.
It is clear, therefore, that by placing the aqueous outflow mechanism under stress (as done while doing the Test) eyes which have an impeded aqueous outflow, probably as a result of structural changes in the outflow mechanism due to chronic simple glaucoma, may be detected by the Bulbar Pressure Test.
Moreover, as the O.F. values showed a rise after the miotic treatment and filtering operation, the test may he employed as a working guide in judging the adequacy of the treatment-medical or surgical as the case may be.
It is not our intention to suggest that the test will replace Tonography as the precise mechanism for measuring the aqueous outflow. However, it may prove to be a valuable clinical adjunct for glaucoma detection. By its very nature and simplicity the test may permit its widespread use.
| Summary and Conclusions|| |
l. Bulbar pressure test was done on 20 normal eyes and 20 eyes suffering from chronic simple glaucoma.
2. It was found that the highest O.F. value in cases of chronic simple glaucoma (i.e. 25%) was less than the lowest O.F. value (30%) in normal eyes.
3. It is suggested that Bulbar Pressure Test is a useful clinical adjunct in the diagnosis of glaucoma, because of its simplicity and reliability.
| References|| |
Blaxter P. L. (1953). Brit. J. Ophth. 37:641.
[Figure - 1]
[Table - 1], [Table - 2]