Confrontation.

As presented on optometry and vision science 1st year.

1. Confrontation Test. ANUJA DHAKAL 2ND YEAR,BOVS. NEH

2. confrontation test is one of the simple,preliminary test which is done for gross visual field(peripheral) screening both monicularly and binoculary. it falls under kinetic perimetry. confrontation testing is best viewed as a pass/fail test as the results are quantative. No equiptment is necessary; it can be done anytime or anyplace. principle used in this test is that the field of vision of examiner’s right eye is same as field of patient’s left eye. INTRODUCTION.

3. PROCEDURE:

4. procedure contd; prior to testing of visual field insure central vision and visual acuity is intact. Initially,position yourself in front of the patient facing her/him with your face level , at a distance of about a metre(variable). With the examiner seated directly across from the pt,the pt should direct their gaze to the corresponding eye of the examiner without the movement of head. For examining right eye,instruct patient to cover their left eye and fixate the gaze at examiner’s right eye,at the same time you as the examiner close your right eye and viceversa.

5. prodedure contd; with the patient fixating the examiner’s eye,the test object or a finger is moved in a flat plane midway between the patient and examiner from the periphery in an arc stimulating the curve of an imaginary perimeter as far as possible . The patient is instructed to report when he or she first sees the object.the test is usually done in 8 half meridians(0,45,90,135,180,225,270,315 degrees). Two test object can be used simultaneously ,one in temporal field and one in the nasal field.This technique is valuable in detecting hemianopic field defects that might otherwise be easily missed.

6. prodedure contd ; Harrington refers to this process as the extinction phenomenon :the presence of the stimulus in the seeing field gives the impression of “extinguishing” the test object in the nonseeing field. first test the binocular field and then test each eye separately a defect is detected by the absence of a patient response to the showing target,when the target is visible to you. The process should be repeated in each quadrants for each eye separately and establish the boundaries.

7. The conventional method patient examiner 1 m

8. If we are able to stretch to test the limits of the patient's field, then we are no longer comparing the patient's visual field to our visual field.

9. A better method for confrontation field testing

10. geometry of confrontation testing;

11. The test distance(d) should depend on the purpose of the test;if the examiners desires to test the temporal field of 60 degree,then a distance of 60 cm would be necessary.Algrebrically cos 60 = b/h ½ = or, ½ = d/2y :y = d.( hence,for 60 degrees evaluation distance between patient and examiner would be equal to test distance, and most people have arm length less than 70 com so 60 cm would be ideal). If someone performs this test using 100cm between examiner and patient,test distance should also be 100cm even for 60 degrees of temporal field. d/2 y b = d/2

12. interpretations of confrontation test: A comparision of examiner and patient’s fields is made,the assumption being that you,as the examiner have normal visual field. If the patient cant see the object when it is visible to you then it is interpretated that patient may have visual field defect. If defect is detected ,re-examine that area and define it further. Any discrepancies between the examiner’s and patient’s visual field after repetations then should prompt further field examinations. With a suitable test object,the examiner can outline the patient’s blind spot ,demonstrating what is meant by the disapperance of the test object.

13. visual field defects

14. B itemporal hemianopsia right eye left eye

15.   The confrontation field of a bitemporal hemianopsia would look like this:

16. Drawbacks of confrontation test. Drawbacks of this approach alone is that early(or even moderate) visual field defect often go unnoticed ,particularly if one eye is affected. It is a subjective test and sometimes misinterpretations of report may be presented if the patient has poor compliance, usually pediatric and geratric patients. It is the screening test and the diagnosis can’t be made alone with this test.

17. THANK YOU.