Indian Journal of Ophthalmology

: 1987  |  Volume : 35  |  Issue : 1  |  Page : 7--10

Slit lamp ophthalmodynamometry in internal carotid artery insufficiency

Rajiv Nath, MK Mehra, D Nag, J Agarwal 
 King George's Medical College, Lucknow, India

Correspondence Address:
Rajiv Nath
King George«SQ»s Medical College, Lucknow


Slit lamp ophthalmodynamometry was done by Dynoptor instrument in 6 cases of internal carotid artery, insufficiency, 18 cases of middle cerebral artery thrombosis and 20 control cases free from neurological disease. The average difference between the ophthalmic artery pressures of the two sides was 7.6% (diastolic) and 4.8% (systolic) in control cases. It was 6.6% (diastolic) and 4.6% (systolic) in cases of middle cerebral artery thrombosis. This difference was much higher in cases of -sub internal carotid artery insufficiency (41.3% «SQ»diastolic and 25.4% in systolic); thus elucidating the role of ophthalmodynamometry as a non-invasive technique in diagnosis of these cases.

How to cite this article:
Nath R, Mehra M K, Nag D, Agarwal J. Slit lamp ophthalmodynamometry in internal carotid artery insufficiency.Indian J Ophthalmol 1987;35:7-10

How to cite this URL:
Nath R, Mehra M K, Nag D, Agarwal J. Slit lamp ophthalmodynamometry in internal carotid artery insufficiency. Indian J Ophthalmol [serial online] 1987 [cited 2021 Jun 17 ];35:7-10
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Full Text

Ophthalmodynamometry represents an attempt to measure the blood pressure of the ophthalmic artery. Several types of ophthalmodynamometers have been tried in the past. Friedman (1966) designed the first ophthalmodynamometry for slit lam: observations and Sisler (1972) [2]sub devised Dynoptor instrument. This involves application of pressure against the cornea along a precisely anteroposterior axis of the globe, coincident with the examiner's axis of visualization of optic disc. The correlation coefficient between the two eyes is said to be nearer to unity with Dynoptor.

This investigation is said to be an important diagnostic tool in carotid artery insufficiency states. Several workers have upheld it while others have brushed it aside saying that it has a number of limitations. However, this technique is a safe and non-invasive method to diagnose a state of decreased ophthalmic artery pressure resulting from carotid insufficiency.


This study was undertaken in collaboration with the Neurology Department of King George's Medical College and Hospital, Lucknow. 6 cases of internal carotid artery insufficiency (group I) and 18 patients of middle cerebral artery insufficiency (Group II) were subjected to this procedure against

In patients of Group II al o, the pattern of Ophthalmodynamometric pressure was well within normal limits, that have been laid down (average Diastolic percentage of difference was 6.6% and systolic percentage of difference was 4.6% - upto a maximum percentage of difference of 13.6% in diastolic and 8.7% in systolic).

In Group I all the 6 cases show a marked difference between the two eyes, which is much higher than Group I and Group 1I cases (as is clear from [Table 1]. The Ophthalmic Artery Pressure of these cases has been demonstrated in [Table 2]. The average Diastolic difference between the two eyes was 41.3% (range 27.6 - 57.1), and average systolic difference 25.4% (range 18.4 - 43.5). Thus the percentage difference is six to seven times higher than the group II and Group III cases. This leaves no room for any doubt regarding the role of ophthalmodynamometry in diagnosing carotid insufficiency.

A control group of 20 patients who were free from any neurological disease. The ophthalmic artery pressure was measured by A.0. Dynoptor instrument fitted on Heig Street Slit Lamp. The apparatus consists of a high concave lens (-60 D) of 8 mm diameter, which is brought in contact with anaesthetised cornea, to provide a view of the optic disc and vessels through the oculars of slit lamp (Pupils being fully dilated with Phenyephrine 10% eye drops). An axial pressure is applied over the cornea, through the same lens by turning the pressure dial of the instrument, which provides a calibrated pressure application (in grams pressure, each small division being equivalent of 4 gms). By numerical coincidence, it has been found that for normal intraocular pressure (of around 15 mm Hg) the applied pressure in gms is numerically same as the resultant intraocular pressure in mm Hg. Our purpose was of simply comparing 2 eyes and so conversion scales were not required.

The point where full amplitude pulsation of central retinal artery is seen, is noted. This is the ophthalmic diastolic reading. The pressure is further increased, keeping a full view of the optic disc, till the pulsations just cease. This is ophthalmic systole. The joystick of the slit lamp is pulled back immediately and reading on the dial is recorded.

Before this procedure, blood pressure was measured in each brachial artery. Tonometry was done by a Schiotz tonometer. Either of the two eyes was examined first, followed by the other eye.

The pertinent difference between the grams of pressure of the eyes was selected as the most convenient manner of comparison.


The accompanying errors are small and moreover, they do not invalidate the comparative purpose.


In our control cases (Group III) the average percentage of difference between the two sides 'was found to be 7.6% for Diastolic and 4.8% for Systolic. These patients were free from neurological illnesses, so that a figure less than this can definitely be taken as measurement within normal limits. According to Spalter's study (1959) (4)sub of 50 normal subjects, a difference of 10% Diastolic and 15% Systolic can be considered as normal.[5]


1Sanborn et al: Arch. Ophth: 1981, 99: 1811-1813.
2Sisler H.A.:AJO, 1972, 74:987-988.
3Smith et al: JAf1A, 1959, 170: 1403.
4Spalter H.F.: AJO, 1959, 47: 453.
5Thomas & Petrohelos: AJO, 1953, 36: 335-346.