SCIENTIFIC REPORT

“Reference values of intraocular pressure measured by EASYTON tonometer and Goldman tonometer for eyelids with epicanthic fold (Mongolian fold) in residents of Kazakhstan”

Objective: To perform a comparative assessment of the IOP measurement using EASYTON tonometer and Goldman tonometer for the eyes with an epicanthic eyelid fold – Mongolian race representatives (residents of Kazakhstan).

A characteristic feature of Mongoloid/Mongolian races, also found in Northern Europe and in countries like Ireland, is the so-called epicanthic or Mongolian fold, a fold in the upper eyelid in the innermost corner of the eye. To a greater or lesser extent, it covers the lacrimal tubercle. This is particularly concentrated in representatives of the Central Asian mongoloid races, though it is also found to a lesser extent in many other ethnic groups around the world. This study set out to ascertain if the epicanthic fold impacts on IOP measurement through the eyelid.

Material and methods.

The IOP measurements were carried out in the Eye Microsurgery Public State Enterprise (with the Right of Economic Management) “The Prof. H.Zh.Makazhanov Polyclinic No. 1” of Karaganda city and the «TENSV Clinic» LLP – the clinical bases of the Ophthalmologic Chair of the Medical University of Karaganda (MUK).

150 patients (150 eyes) were examined overall. For each patient, IOP was initially measured with the Goldman tonometer and then with the EASYTON tonometer. The study was conducted under the provisions of ISO 8612.

In total, the 150 reference IOP measurements were categorized in the following 4 ranges:

  1. Under 17 mmHg: 40 measurements;
  2. 17 – 23 mmHg: 40 measurements;
  3. Above 23 mmHg: 40 measurements;
  4. High astigmatism: 30 measurements.

The IOP measurement procedure consisted of the following steps:

The device rod was gently set on the eyelid 2-3 millimeters above the edge of the lid and above the upper border of the iris. Holding the tonometer upright, the rod was gently depressed by 2-3 mm. The dynamic impact was experienced like soft vibration. During the measurements it was ensured that the protective ring of the tonometer did not touch the eyelid, and remained 2-3 mm from the eyelid.

If the tonometer is depressed too much, the tonometer emits a continuous monophonic sound signal that ceases when the tonometer is raised to a level that is appropriate for measurement.

The measurement results were grouped according to the 4 above ranges and are included in tabellar and graphic form in the report below.

                                                                Study authors

Head of the Opthalmology Chair of the Medical University of Karaganda (MUK).

Holder of Habilitation Degree in Medicine, Professor, Doctor of higher category

Shousterov Y.A.

Head of Unit,

Ocular Microsurgery and Chief ophthalmologist of Karaganda Region,

D.E. Toksambaeva

Table 1. IOP results obtained using EASYTON tonometer compared to Goldmann tonometer

                                            Table 1.             Patients with IOP below 17 mmHg
Patient No. Goldman tonometer EASYTON Patient No. Goldman tonometer EASYTON
1 10 10 21 16 16
2 11 10 22 16 16
3 11 12 23 16 18
4 11 10 24 16 15
5 11 12 25 16 17
6 12 12 26 16 16
7 12 13 27 16 18
8 12 12 28 16 16
9 13 13 29 16 16
10 13 12 30 16 18
11 13 13 31 16 16
12 13 12 32 16 17
13 14 14 33 16 16
14 14 15 34 16 16
15 14 15 35 16 16
16 15 14 36 16 16
17 15 16 37 16 16
18 15 15 38 16 16
19 15 16 39 16 17
20 15 15 40 16 15

Table 2: IOP results obtained using EASYTON tonometer compared to Goldmann tonometer

Table 2.            Patients with IOP in the range 17 to 23 mmHg
Patient No. Goldman tonometer EASYTON Patient No. Goldman tonometer EASYTON
1 17 16 21 19 20
2 17 20 22 20 20
3 17 18 23 20 20
4 17 16 24 20 20
5 17 16 25 20 19
6 17 15 26 20 23
7 17 16 27 20 22
8 17 19 28 21 23
9 17 16 29 21 24
10 17 16 30 21 24
11 18 20 31 21 22
12 18 19 32 22 25
13 18 16 33 22 19
14 19 19 34 22 25
15 19 17 35 22 22
16 19 17 36 22 23
17 19 19 37 23 23
18 19 20 38 23 23
19 19 19 39 23 25
20 19 20 40 23 21

Table 3. IOP results obtained using EASYTON tonometer compared to Goldmann tonometer

Table 3.        Patients with IOP in the range above 23 mmHg
Patient No. Goldman

tonometer

EASYTON Patient No. Goldman

tonometer

EASYTON
1 24 24 21 25 26
2 24 25 22 25 24
3 24 23 23 25 25
4 24 24 24 26 26
5 24 26 25 26 26
6 24 24 26 26 24
7 24 25 27 26 27
8 25 27 28 26 24
9 25 25 29 26 27
10 25 26 30 27 27
11 25 28 31 27 28
12 25 26 32 28 28
13 25 26 33 28 29
14 25 23 34 28 28
15 25 24 35 29 31
16 25 25 36 29 29
17 25 25 37 32 33
18 25 26 38 38 36
19 25 26 39 40 42
20 25 25 40 41 43

Correlation of IOP indicators obtained using the EASYTON tonometer and Goldman tonometer

Diagram 1

Table 4. The results of IOP measurements performed by EASYTON tonometer compared to those obtained using Goldman tonometer as a reference standard for patients with high astigmatism (over 3 diopters)

Table 4a.  Patients with high astigmatism and IOP under 17 mmHg
Test Object No.          Goldman tonometer EASYTON
1 14                        14
2 15 14
3 15 16
4 15 17
5 16 17
6 16 18
7 16 16
8 16 18
9 16 17
10 16 16
Table 4b.    Patients with high astigmatism and IOP of 17 to 23 mmHg
Test object         11 17 19
12 17 17
13 17 18
14 17 19
15 18 20
16 18 20
17 20 22
18 21 20
19 22 24
20 23 22
Table 4c. Patients with high astigmatism and IOP above 23 mmHg
Test object        21 24 25
22 24 26
23 25 23
24 25 26
25 25 27
26 26 26
27 27 29
28 31 30
29 31 32
30 32 32

Diagram 2. Correlation of IOP indicators obtained by EASYTON tonometer and Goldman tonometer in patients with high astigmatism

Conclusion: the measurements obtained using EASYTON tonometer are strongly correlated to the values obtained using the Goldman tonometer (see Diagrams 1, 2).

No particularities in the measurement of IOP were found in people with an eyelid epicanthic fold (Mongolian fold) in residents of Kazakhstan.

MINISTRY OF HEALTH CARE OF THE REPUBLIC OF KAZAKHSTAN

Public State Enterprise with the Right of Economic Management “The Prof. H.Zh.Makazhanov Polyclinic No. 1”

Approved

Director

D. T. Kurmangaliev

12/29/2019

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