|LETTER TO EDITOR
|Year : 2004 | Volume
| Issue : 3 | Page : 257-8
K S Gopal
Source of Support: None, Conflict of Interest: None
Keywords: Circadian Rhythm, Glaucoma, Open-Angle, etiology, Humans, Intraocular Pressure, Ocular Hypertension, complications, physiopathology
|How to cite this article:|
Gopal K S. Ocular hypertension. Indian J Ophthalmol 2004;52:257
I wish to make a few points about the article 'Ocular hypertension' by Dr. Ravi Thomas et al. Congratulations on a meticulous job.
The conclusion is that the initial intraocular pressure (IOP) and diurnal variation recorded at the first visit give an indication about the likelihood of developing glaucoma. The higher the diurnal variation of IOP initially, the higher the chance of developing glaucoma.
Open angle glaucoma has been defined by IOP levels, disc appearance and field changes either singularly or in various combinations across time or at the same time. Factors like myopia, diabetes mellitus, cardiovascular disease and central retinal vein occlusion increase the chances of developing glaucoma. The IOP distribution curves of glaucomatous and ocular hypertensive eyes show a significant overlap. Under these circumstances an IOP level of 21 has no real clinical significance. Should we consider ocular hypertension as a separate entity from POAG? If the answer is 'yes' then the term "progression of OHT to glaucoma" has no meaning.
Ocular hypertension is distinct from POAG because:
1. One can have disc and field changes of POAG even if the IOP is well below the so-called 'normal'.
2. One can have IOP above 21 for quite some time without ever developing disc and field changes.
In the first situation, the first step OHT is never there and in the second situation OHT remains OHT and does not progress. In only a small percentage of patients with OHT does second step POAG creep in.
The term 'progression' is meaningful only if we consider OHT as the first step in POAG. The difficulty is in convincing oneself beyond reasonable doubt that the OHT is indeed the first step in POAG.
Do POAG and OHT have the same risk factors? A general ophthalmologist is more likely to encounter a case of OHT than a case of POAG. How does he treat such a case? At present the only measurable and alterable attribute in this triad is pressure. Thus, we continue to depend solely on IOP.
| References|| |
Thomas R, Parik R, George R, Kumar RS, Muliyil J. Five-year risk of progression of ocular hypertension to primary open angle glaucoma. A population-based study. Indian J Ophthalmol