[The upper limit of individual normal range of intraocular pressure--a personalized criterion for IOP evaluation]

To determine clinical value of the use of the upper limit of individual normal range of intraocular pressure (IOP) in glaucoma diagnosing.

The study enrolled 229 conditionally healthy participants (229 eyes) with no ocular complaints after a basic ophthalmic assessment. Ocular blood flow and IOP were measured with Ocular Blood Flow Analyzer (Paradigm Medical Industries). An original formula was further used for calculation of the upper limit of normal range of IOP. All patients were divided into two groups depending on whether or not their IOP fell within the statistically normal range, i.e. was less than 21 mmHg. Thus, group 1 included 193 patients (193 eyes) with IOP from 6.7 to 21.0 mmHg, group 2 -36 patients (36 eyes) with IOP from 21.7 to 30.8 mmHg. Glaucoma diagnosis was made from automated perimetry (Humphrey Visual Field Analyzer) and retinal tomography (HRT3, Cirrus HD-OCT) findings.

In group 1, the IOP was found to exceed the upper limit of individual normal range in 38 eyes, thus indicating the probability of glaucoma; of them, in 23 patients (60.5%) the diagnosis was confirmed by further examinations. In the rest 155 eyes from group 1 the IOP matched the individual normal range; of them, glaucoma was ruled out in 154 eyes (99.35%). In group 2, a risk of glaucoma was determined in 27 eyes, of which 24 (88.9%) were further diagnosed. In 9 eyes the IOP exceeded the statistically normal values and yet was within the individual normal range. In none of those 9 cases glaucoma was found.

The upper limit of individual normal range of IOP is a personalized diagnostic criterion, which is more significant for evaluation of the risk of having or developing glaucoma than the upper limit of statistically normal range (21 mmHg).