A method for measuring intraocular pressure using artificial intelligence technology and fixed-force applanation tonometry

Purpose. To estimate the accuracy of IOP measurement using artificial intelligence (AI) technologies and applanation tonometry with fixed strength. Material and methods. 290 patients (576 eyes) underwent applanation tonometry according to Maklakov with tonometer weights of 5, 10, and 15 g using a modified elastotonometry technique followed by an analysis of impression quality and diameter measurements by three independent ophthalmologist experts. The prints were then fed into a neural network to check the repeatability and reproducibility of the measurements. Results. The comparison of the diameters of the Maklakov tonometer prints determined by AI based on the neural network with the measurements data provided by three experts showed that neural network underestimates the measurement results by an average of 0.27 (-3.81; 4.35) mm Hg. At the same time, the intraclass correlation coefficient for all prints was 98.3%. The accuracy of diameter measurements of prints by neural network differs for tonometers of different weights, e.g. for a 5 g tonometer the difference was 0.06 (-3.38; 3.49) mm Hg, for 10 g and 15 g tonometers was 0.14 (-3.8; 3.51) and 0.95 (-3.84; 5.74) mm Hg, respectively. Conclusion. High accuracy and reproducibility of the measurements by the neural network, was shown to surpass the reproducibility of human-implemented measurements.

1. Resnikoff S., Felch W., Gauthier T.M., Spivey B. The number of ophthalmologists in practice and training worldwide: A growing gap despite more than 200 000 practitioners. Br. J. Ophthalmol. 2012; 96 (6): 783–7. doi:10.1136/ bjophthalmol-2011-301378

2. Wu Y., Luttrell I., Feng S., et al. Development and validation of a machine learning, smartphone-based tonometer. Br. J. Ophthalmol. 2020; 104 (10): 1394–8. doi:10.1136/bjophthalmol-2019-315446

3. Pathipati A.S., Wood E.H., Lam C.K., S les C.S., Moshfeghi D.M. Visual acuity measured with a smartphone app is more accurate than Snellen testing by emergency department providers. Graefe’s Arch. Clin. Exp. Ophthalmol. 2016; 254 (6): 1175–80. doi:10.1007/s00417-016-3291-4

4. Bastawrous A., Rono H.K., Livingstone I.A.T., et al. Development and validation of a smartphone-based visual acuity test (peek acuity) for clinical practice and Community-Based Fieldwork. JAMA Ophthalmol. 2015; 133 (8): 930–7. doi:10.1001/jamaophthalmol.2015.1468

5. Ludwig C.A., Murthy S.I., Pappuru R.R., et al. A novel smartphone ophthalmic imaging adapter: User feasibility studies in Hyderabad, India. Indian J. Ophthalmol. 2016; 64 (3): 191–200. doi:10.4103/0301-4738.181742

6. Ludwig C.A., Newsom M.R., Jais A., et al. Training time and quality of smartphone-based anterior segment screening in rural India. Clin. Ophthalmol. 2017; 11: 1301–7. doi:10.2147/OPTH.S134656

7. Vilela M.A., Valen a F.M., Barreto P.K., Amaral C.E., Pellanda L.C. Agreement between retinal images obtained via smartphones and images obtained with retinal cameras or fundoscopic exams – Systematic review and meta-analysis. Clin. Ophthalmol. 2018; 12: 2581–9. doi:10.2147/OPTH. S182022

8. Rajalakshmi R., Arulmalar S., Usha M., et al. Validation of smartphone based retinal photography for diabetic retinopathy screening. PLoS One. 2015; 10 (9): e0138285. doi:10.1371/journal.pone.0138285

9. Russo A., Morescalchi F., Costagliola C., Delcassi L., Semeraro F. Comparison of smartphone ophthalmoscopy with slit-lamp biomicroscopy for grading diabetic retinopathy. Am. J. Ophthalmol. 2015; 159 (2): 360–4. e1. doi:10.1016/j. ajo.2014.11.008

10. Russo A., Mapham W., Turano R., et al. Comparison of smartphone ophthalmoscopy with slit-lamp biomicroscopy for grading vertical cup-to-disc ratio. J. Glaucoma. 2016; 25 (9): e777–81. doi:10.1097/IJG.0000000000000499

11. Bastawrous A., Giardini M.E., Bolster N.M., et al. Clinical validation of a smartphone-based adapter for optic disc imaging in Kenya. JAMA Ophthalmol. 2016; 134 (2): 151–8. doi:10.1001/jamaophthalmol.2015.4625

12. Goyal A., Gopalakrishnan M., Anantharaman G., et al. Smartphone guided wide-field imaging for retinopathy of prematurity in neonatal intensive care unit - A Smart ROP (SROP) initiative. Indian J. Ophthalmol. 2019; 67 (6): 840–5. doi:10.4103/ijo.IJO_1177_18

13. Antonov A.A., Karlova E.V., Brezhnev A.Y., Dorofeev D.A. Current state of ophthalmic tonometry. Vestnik oftal’mologii. 2020; 136 (6): 100–7 (in Russian). doi:10.17116/oftalma2020136061100

14. Gorodnichiy V.V., Dorofeev D.A., Zavadsky P.C., et al. Risk factors, pathogenic factors in progression of glaucoma by results of multicenter study of Russian glaucoma society. Medical and Biological Problems of Life Activity. 2012; 8 (2): 57–69 (in Russian). http://eyenews.club/files/r_70_50/ new-266_selection.pdf

15. Avdeev R.V., Alexandrov A.S., Basinsky A.S., et al. Clinical and epidemiological study of risk factors of glaucoma development and progression. Russian ophthalmological journal, 2013; 6 (3): 4–11 (in Russian)]. https://elibrary.ru/ item.asp?id=19415263

16. Dorofeev D.A., Kirilik E.V., Klimova A.V., Solovieva A.B. Effect of retinal protective therapy on optical coherence tomography angiography (pilot study). Vestnik oftalmologii. 2021; 137 (1): 60–7 (in Russian). doi:10.17116/oftalma202113701160

17. Gusarevich A.А., Zavadski P.C., Kuroyedov A.V., et al. The correct choice of monotherapy with prostaglandins analogues/prostamides at the start of treatment for newly diagnosed glaucoma (as results of a multicenter study). National Journal glaucoma. 2020; 19 (3): 43–57 (in Russian). doi:10.25700/ NJG.2020.03.05

18. Strakhov V.V., Egorov E.A., Erichev V.P., et al. The influence of long-term retinal protective therapy on glaucoma progression according to structural and functional tests. Vestnik oftal’mologii. 2020; 136 (5): 58–66 (in Russian). doi:10.17116/oftalma202013605158

19. Dorofeev D.A., Kryzhanovskaya A.V., Tsyganov A.Z. Effectiveness of antihypertensive conservative-free therapy with fixed combination of bimatoprost and timolol (intermediate results). Vestnik oftal’mologii. 2020; 136 (2): 73–80 (in Russian). doi:10.17116/ oftalma202013602173

20. Avdeev R.V., Bakunina N.A., Basinsky A.S., et al. Management of glaucoma progression. National journal glaucoma. 2019; 18 (1): 45–58 (in Russian). doi:10.25700/NJG.2019.01.07

21. Maklakov N.A. More on ophthalmotonometry. Surgical Annals. 1883; (4): 1–11 (in Russian).

22. Wind C.A., Kaufman H.E. Clinical evaluation of the Halberg hand applanation tonometer. Ann Ophthalmol. 1972; 4 (8): 631–41.

23. Posner A. The applanometer, a modified Maklakov applanation tonometer. Eye Ear Nose Throat Mon. 1965; 4: 77–80.

24. Vurdaft A.E. On the precision of Polyak measuring scales in Maklakov tonometry. National journal glaucoma. 2017; 16 (4): 11–22 (in Russian).

25. Dorofeev D.A., Vizgalova L.O., Gorobets A.V., et al. The possibilities of artificial intelligence use in the assessment of Maklakov intraocular pressure prints. Natsional’nyi zhurnal glaukoma. 2020; 19 (1): 20–7 (in Russian). doi:10.25700/ NJG.2020.01.03

26. Avetisov S.E., Bubnova I.A., Antonov A.A. Once more about the diagnostic capacities of elastic tonometry. Vestnik oftal’mologii. 2008; 124 (5): 19–21 (in Russian) https://elibrary.ru/item.asp?id=11632985

27. Nesterov A.P., Bunin A.Ya. New classification of primary glaucoma. Vestnik ophthal’mologii. 1977; 5: 38–42 (in Russian). https://elibrary.ru/contents.asp?id=34562365

28. Spaide T., Wu Y., Yanagihara R.T., et al. Using deep learning to automate goldmann applanation tonometry readings. Ophthalmology. 2020; 127 (11): 1498–506. doi:10.1016/j.ophtha.2020.04.033

29. Cook J.A., Botello A.P., Elders A., et al. Systematic review of the agreement of tonometers with goldmann applanation tonometry. Ophthalmology. 2012; 119 (8): 1552–7. doi:10.1016/j.ophtha.2012.02.030

30. Barkana Y., Gutfreund S. Measurement of the difference in intraocular pressure between the sitting and lying body positions in healthy subjects: Direct comparison of the Icare Pro with the Goldmann applanation tonometer, Pneumatonometer and Tonopen XL. Clin. Exp. Ophthalmol. 2014; 42 (7): 608–14. doi:10.1111/ceo.12272

31. Barkana Y. Postural change in intraocular pressure: A comparison of measurement with a Goldmann Tonometer, Tonopen XL, Pneumatonometer, and HA-2. J. Glaucoma. 2014; 23 (1): e 23–8. doi:10.1097/IJG.0b013e3182a0762f