Editors Selection (IGR: 7-1) | International Glaucoma Review #238

Editors Selection IGR 7-1

Examination methods: Phosphene tonometry

Comment by Michael Diestelhorst on:

11705 Reproducibility of self-measured intraocular pressure with the phosphene tonometer in patients with ocular hypertension and early to advanced glaucoma, Brigatti L; Maguluri S, Journal of Glaucoma, 2005; 14: 36-39

Brigatti et al. (98) studied a new self-administered phosphene tonometer in 33 eyes with glaucoma and three with OH.

Although the phosphene technique is known since Aristotle, the new device needed to be studied with regards to its sensitivity and specificity and was compared with the Goldmann applanation tonometer. A prerequisite of this method is that the patients can handle the device properly and are able to notice the phosphenes as they take place.

The authors found that about 70% of the patients studied here were able to notice the entoptic phenomenon, 8% could see it in one eye only, and 19% did not see it in either eye. The authors excluded eyes that could not see the phosphenes from further analyses.

The data from the other eyes showed a mean difference of 1.7 mmHg &plm; 1.7 mmHg between the two methods studied. The authors conclude that a systematic, reproducible error between the new device and the Goldmann tonometry may be clinically acceptable and that self-tonometry may play an important role in the clinical follow-up of our glaucoma patients.

A systematic, reproducible error between the phosphene tonometer and the Goldmann tonometry may be clinically acceptable

As rewarding as self-tonometry may be this study has clearly shown that the new technique is not appropriate for our patients even if they can see the phosphenes.

Not only is the handling rather demanding, but patients may be pretending to see the phenomenon and the data collected may be confusing not only the patients. A much better technique is the self-tonometer Ocutone S, which was introduced some years ago in Europe. It is based on the applanation tonometry technique and can be handled quite nicely. However, even the sophisticated Ocutone S should not keep us from asking for an intra-ocular telemetric device to collect data 24/7 and give us the chance to discuss the pros and cons of non-adherence or surgery with our patients when we know the IOP!

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Issue 7-1

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