Introduction:
Glaucoma is a widespread, socially significant, progressive disease that is characterized by changes in the optic nerve head and can lead to impaired visual function in cases with absence of proper diagnosis and treatment. Confirmation of the disease is based on multiple factors, and the correct choice of diagnostic tool is essential.
Aim:
The aim of the study is to establish the relationship between the most commonly used screening methods for glaucoma diagnosis, the sources of error and the potential pitfalls for over- and underdiagnosis.
Materials and Methods:
A literature analysis was conducted regarding the most common disadvantages of routinely used methods. The results of a prospective study with 27 randomly selected participants are presented. After filling out an informed consent form, a full eye examination was conducted, including measurement of intraocular pressure (IOP) with different tonopachymeters and ultrasound pachymetry by the same researcher, at a similar time of the day. For this purpose, the Nidek Tonopachy NT 530P and Corvis ST non-contact tonometers were used. Both devices have a built-in pachymeter. The effect of applied artificial tears eye drops on the anterior ocular surface immediately before the measurement was also evaluated. The Alcon OcuScan device was used for ultrasound pachymetry. SPSS V.19 was used for statistical analysis.
Results:
There was comparability of the results obtained by both devices in terms of the obtained values for corneal thickness (CCT), measured in micrometers: for the right eye (OD) CCT measured with the NT 530P non-contact tonometer was 536.15 ± 45.94 μm and when using the Corvis ST, 534.63 ± 42.17 μm, respectively, p < 0.01. The results obtained with ultrasound pachymetry were 539.41 ± 42.83 μm. For the left eye (OS), the results obtained with NT 530P were 553.11 ± 32.07 μm and when using Corvis ST: 553.85 ± 36.85 μm, p < 0.01. The results obtained from ultrasound pachymetry were 554.78 ± 32.82 μm. The measurement of IOP with both devices showed slight differences, with the values measured with Corvis ST being on average 1.45 ± 4.23 mmHg lower than those obtained with NT530P in the same patients. The application of drops immediately before the measurement did not have a statistically significant effect on the obtained IOP and CCT values.
Conclusion:
The incidence of glaucoma, the significant effect that the disease has on visual acuity and quality of life of patients, as well as the economic burden for the individual and the community, emphasize the importance of early and correct diagnosis. A thorough understanding of the principles and potential errors in the use of different diagnostic methods could reduce the risk of over- and underdiagnosis of the disease and improve the effect of treatment.
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