There are few studies which compared the GAT with and without fluorescein. What is the method used by them in either group?
Dear Tarak Rao. Thanks for the answer. Even i use green filter. But in journal search , i dint get any evidence for the same. Can u provide me with some evidence for using green filter?
No filters!!! blue one is to activate fluorescein to obtain green highlight of surrounding applanation cone! Without flourescein blue filter does not excitate nothing and Green filters reduce the light. If you do not use fluorescein you have to pay attention to the border of the cone to obtain same picture as fluorescein.
First of all, it is important to mention that the Goldmann applanation tonometry (GAT) without fluorescein underestimates the intraocular pressure. Studies compared GAT with fluorescein and GAT without fluorescein and consistently found a significant difference between the methods. Bright et al. (Am J Optom Physiol Opt, 1981) performed the GAT measurements without fluorescein using white light.
Except where the patient is sensitive to fluoresceine why waste time trying to identify nearly invisible mires that may not give very accurate reading?
True enough. One should use fluorescein except in the very rare patient that is allergic to it (I have only one).
The width of the mire should be 1/10 the diameter of circle width for accurate measurement. Without fluorescein (or with too little fluorescein) the edges of mires may be more difficult to visualize properly and errors may be more likely. For these rare patients one occasionally has to do the best one can - perhaps supplement / support such a measurement with another instrument that does not require fluorescein (i.e. tonopen)
Main problem is the difficulty in some countries to obtain fluorescein stripes since haag-streit ceased its production. There are different brands Made with macromolecolar fluorescein but it works less efficently. But non we have different ways to maestre IOP like Pascal tonometer or air systems
i have been performing applanation tonometry, without fluorsein or any kind of filter, for fifteen years and did not feel any trouble at all. No need of any evidence just try yourself . You will experience the difference by yourself . let me know after this.
Enzo -How pascal work? Reliability?air puff ?variability in measurement?
Jamshed Ahmed, how do you manage to see the mires and get good readings all the time. Perhaps your hints will help us with some allergic patients.
Pascal works on dynamic applanation system like mckay margh tono meter seen in early 80'. It is one of the most precise and accurate system independent from corneal thickness. There are several version some of that may be link ed to a computer to perform a medical history of the patients.
Enzo/. Thanks for the reply.By air system you want to mean air puff tonometer? How much reliable it is? Do you have any idea on comparative study on Goldman appal nation tonometer versus tonopen Avia?)
No filters, be aware of under estimation of pressure without fluorescein. Bio Glo strips can be obtained from Hub Pharmaceuticals. www.hubrx.com. I am using the rebound tonometer with great success. Busy with a study comparing RBT to GAT and The ORA. Will keep you posted.
No filter! But you tends to understimate the pressure
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