The desirability of providing the patient with a fixation target during tonometry is well known. With the patient's eyes in a more or less steady position, the risk of corneal abrasion is minimized and the examiner may expect more trustworthy readings. For tonography examinations, proper fixation by the patient is all the more important.
Some ophthalmologists have a small ceiling light mounted in their offices above the examining table. This is generally satisfactory, but it does not provide the flexibility which is often necessary in getting the patient to maintain the most desirable position of the eyes. In some clinics, a painted ball or other fixation target is held directly above the patient by means of an adjustable stand. This has the minor disadvantage that the fear of the object's falling may occasionally disturb a patient and interfere with relaxation.
After a number of possible arrangements were tried, a simple
ASKOVITZ . A Fixation Light for Tonometry and Tonography. AMA Arch Ophthalmol. 1957;57(2):288-289. doi:10.1001/archopht.1957.00930050298023