Ophthalmodynamometry.

class presentation of optometry and vision sciences 2nd year in nepal.

1. Ophthalmodynamometry. ANUJA DHAKAL BOVS PHASE II,NEH

2. layout Introduction History Anatomy of vasculature Principle Methods and instrumentation Procedure & comparison precautions Clinical significance Indications & contraindications Clinical interpretation

3. INTRODUCTION Ophthalmodynamometry(ODM) is a clinical procedure which is classically assumed to measure the pressure in the ipsilateral ophthalmic artery so that the inferences can be derived about the patency of the internal carotid artery. Ophthalmodynamometry can be used as a screening procedure to detect carotid artery occlusive diseases and,thus, can be important in the prevention of cerebrovascular accidents.

4. HISTORY Bailliart (1917) -introduced the first instrument for assessing the carotid artery function(bailliart ophthalmodynamometer). Baurmann (1936) -noted that the ODM reading was lowered in a patient who had undergone ligation of the ipsilateral carotid artery. Trotot (1944) -first diagnosis of thrombus of ICA ,based on ODM testing-noted that the ODM reading on the ipsilateral side was significantly lower than other side without disease.

5. Anatomy of carotid Artery. In ophthalmodynamometry we are concerned with internal carotid artery. The internal carotid artery doesn’t give off any branches in its cervical portion ,but several small branches arise from the ICA in its petrous portion. The ophthalmic artery is the first major branch of the intracranial carotid artery after it passes through the cavernous sinus.

6. Caroticotympanic artery Pterygoid artery Cavernous artery Hypophyseal artery Meningeal artery Ophthalmic artery Anterior cerebral artery Middle cerebral artery Posterior communicating artery Anterior choroidal artery Central retinal artery Short posterior ciliary artery Long posterior ciliary artery Anterior ciliary artery Muscular arteries Lacrimal artery Supraorbital artery Post & ant ethmoidal arteries Medial palpebral artery Supratrochlear artery Dorsal nasal artery Branches of ICA Branches of ophthalmic artery Ocular branches Orbital branches

7. One of the smallest branches of the ophthalmic artery, but its first,is the central retinal artery. while the clinician is viewing the hemodynamics of the central retinal artery during ophthalmodynamometry ,inferences can be made about the physiologic functioning of the ophthalmic artery ,even though significant collateral formation may occur with other vessels of the face and head.

8. PRINCIPLE Ophthalmodynamometry is based on the principle that due to direct anatomical communication of internal carotid artery with ophthalmic artery ,if the blood flow through the ICA is decreased then the blood flow through ophthalmic artery artery is also decreased.Thus, measures the relative ophthalmic artery pressure. More than 90 % of CA occlusion occur below the origin of ophthalmic artery, thus affecting the blood flow into the ophthalmic artery and retinal arterioles. Pressure is exerted on the sclera to increase IOP to the point where central retinal artery collapses and it is supplied by greater blood through ophthalmic artery.

9. DR.BAILLIART OPHTHALMODYNAMOMETER

10. Methods and Instrumentation There are two classic method used to raise the intraocular pressure to the point at which it causes pulsation and subsequent collapse of the central retinal artery . 1)Compression ophthalmodynamometry 2)Suction ophthalmodynamometry

11. 1)Compression ophthalmodynamometry It is the oldest non invasive method in use. It uses an externally applied graded compression on the globe,the force being created by a coiled spring . As the external force is measured in grams of pressure,conversion scales is used to transpose pressure into millimeters of mercury,or the intraocular pressure equivalent to the external force. The two most common method of compression ophthalmodynamometry are: A) DIAL OPHTHALMODYNAMOMETRY B) LINEAR OPHTHALMODYNAMOMETRY

12. a)DIAL ODM The dial ODM consists of a scale on a dial with two arrows ,mounted on a post containing the spring. The drive arrow is connected to the spring,the second passenger arrow is pushed by the notched drive arrow.

13. b) Linear ODM The linear type of compression ophthalmodynamometry consists of a hollow outer sleeve with a central post that has graduated markings. Pressure on the central post causes the outer sleeve to move along the scale so that the readings can be taken.

14. Procedure for compression ODM.

15. Procedure for compression ODM Patients pupil must be dilated.(usually cycloplegic & mydriatics combination). Explain procedure to the patient. Anesthetize the eyes. Clean and sterilize the ophthalmodynamometer. Indicate appropriate fixation point to the patient. Place footplate of the ODM temporally,close to the equator. Visualize the optic nerve head with ophthalmoscope (either direct or indirect). Gradually increase the pressure(steady rate). Look for venous pulsations from the ophthalmoscope.

16. Procedure contd ; https://youtu.be/5oRoiHflGW4 Note: diastolic pressure . Look for collapse of arteries. Note: systolic pressure . Remove ODM from the eye. Use conversion charts to determine IOPs that equal diastolic and systolic pressures.

17. 2)suction ophthalmodynamometry This is the second method in which negative pressure is applied in the form of suction to increase intraocular pressure sufficiently to cause pulsation and subsequent collapse of the central retinal artery. This procedure also has the same principle of physical basis as compression ODM,but here,a scleral vacuum suction cup is placed in a perilimbal position and a negative pressure is applied.

18. Procedure for suction ophthalmodynamometry

19. Procedure contd; Patient preparation is similar as compression technique. The scleral cups are placed instead at the lateral side around the area of equator . Central retinal artery is viewed through ophthalmoscopy be it direct or indirect. Negative pressure is provided by using a foot pedal or the hand. Noting of both diastolic and systolic pressure is similar to the earlier one. Instrument should be removed immediately from the globe to reduce the length of time and the effect of external pressure on fluids of eye.

20. Advantages of suction ODM over compression ODM The suction method uses all of its force to compress the unlike compression ODM which displaces the eyeball nasally. Examiner doesn’t need to adjust the position unlike compression ODM. Less painful and comfortable than compression method. Sequelea of ODM: Subconjuctival haemorrhage over the lateral rectus at the site of the footplate. Some have noted central scotoma which persists till months. ( https ://www.ncbi.nlm.nih.gov/pmc/articles/PMC2642107/bin/jnma00683-0064.tif) Might result in retinal detachment due to excessive suction pressure.

21. Doppler ophthalmodynamometry This technique described its usefulness in patients with opaque media preventing visualization of the central retinal artery. Instead of an ODM, a miniature stethoscope is used but instead of a diaphragm ,an ultrasound probe that transmits and receives the signal,and then transforms it into audible sound. The probe is placed in the perilimbal area and the pressure is applied until the pulsations of the central retinal artery is heard. The finding and interpretation of doppler ophthalmodynamometry is not clear yet.

22. Precautions to be taken A cooperative patient will make the test more easier and accurate therefore adequate explanation is necessary. The instrumentation should be correct( perpendicular). The footplate can inadvertently slip,causing a corneal abrasion . The fixation and view of blood vessels may be altered due to displaced globe. Venous pulsation shouldn’t be constructed as a diastolic pressure. Patient with bradycardia and cardiac arrhythmia have spurious determinations of both systolic and diastolic end points.

23. Clinical significance: It is significant for detecting presence of carotid artery insufficiency,which is the major cause : Cerebral vascular accident(stroke). Central retinal artery occlusions. In patient with reduced ophthalmic artery pressures,and arteriographically significant carotid artery disease,16% will develop a stroke. ( Busuttil RW, Baker JD, Davidson RK, Machleder HI. Carotid artery stenosis - hemodynamic significance and clinical course. JAMA. 1981 Apr 10; 245 (14):1438–1441)

24. contd; Ophthalmodynamometry is mandatory in patients presenting with amaurosis fugax. Results that indicate higher retinal arterial pressure in diabetes is at a high risk of developing retinopathy.( https://www.nejm.org/doi/full/10.1056/NEJM198003203021201 ) About 2/3rd of patients with documented carotid occlusive disease present with ocular symptoms and if patient have symptomatic carotid artery disease,as many as 88% of them will complain of ocular symptoms. (https://doi.org/10.1016/S0002-9394(14)76496-7)

25. Indications for ODM testing 1) cerebrovascular Signs Complete stroke before arteriography P re and postoperative monitoring of progression of disease. Takayasu’s arteritis hemiplegia Symptoms Transient ischaemic attacks Temporary weakness Tingling or numbness of arm,leg, face or lips Dysarthria Dysphagia Vertigo,dizziness,presyncope seizures

26. 2)carotid Signs Carotid bruit,thrombosis Hemodynamically significant obstruction. Temporal arteritis. Patients on anticoagulant therapy. Monitor postoperative progression Symptoms Transient ischemic attacks

27. 3)ocular Signs Ocular bruit. Hollenhorst plaque. CRVO/BRVO,Arteriosclerotic optic atrophy History of systemic vascular occlusive disease Venous stasis retinopathy Unilateral vascular retinopathy,optic nerve head pallor Unilateral decreased IOP Diabetic,hypertensive patients Symptoms Amaurosis fugax Permanent vision loss secondary to vascular occlusive disease Sudden loss of vision.

28. Contraindications for ODM testing Recent retinal detachment. Patient who has glaucoma or is prone to acute attacks. Any ocular,orbital inflammatory conditions. High myopic eyes. Recent cataract extraction,glaucoma filtration surgery,iridectomy. Retinal or vitreous haemorrhage. Hazy media obstructing visualization of optic nerve head

29. Clinical interpretation •Ophthalmic artery pressure –Systolic: 3/4 th of systolic BP –Diastolic: 2/3 th of diastolic BP •If ophthalmic artery pressure is less than 50% of the corresponding BP, internal carotid artery obstruction is suspected.

30. A difference of 10% between diastolic findings or a difference of 15% between systolic findings between two eyes could be suspected,whereas 15% difference in diastolic & 20% in systolic findings could be taken as suspect. (https://doi.org/10.1016/S0025-7125(16)34244-4) The suspected patient’s medical history and other examinations must be considered before testing for carotid artery occlusive disease. Although interpretation may be a shade difficult in some patients,it yields important clinical data that can be used as a screening test before the invasive arteriography procedure.

31. Thank you ! Stay safe.