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Concordance between the new modular slit-lamp mounted Goldmann applanation tonometer (GAT), conventional slit-lamp
Karthikesh Anche1, Nikhil S Choudhari2, Raghava Chary2
1Department for Technology and Innovation, Center for Innovation and Technology, Dr. Kallam Anji Reddy Campus, L V Prasad Eye Institute, Banjara Hills, Hyderabad, Telangana, India.
Purpose:
To evaluate a new device, the Goldmann applanation tonometer (GAT) mounted on a novel handheld 3D-printed modular slit lamp (MSL), and compare it with the gold standard slit-lamp-mounted GAT and the handheld Perkins tonometer.
Methods:
One hundred eyes from 100 participants were included in this cross-sectional observational study. The MSL mount was customized for the selected tonometer (Model AT030, Carl Zeiss, India). A Samsung Galaxy S2 mobile phone was used for observing mires and photography during tonometry. One observer measured intraocular pressure (IOP) with slit-lamp GAT, and another observer measured with MSL GAT and Perkins tonometers. The tonometry sequence was slit-lamp GAT, MSL GAT, and Perkins tonometer, with a 5-minute interval between readings.
Results:
The median age of participants was 56 years (range: 16-83). The median IOP by slit-lamp GAT was 15 mmHg (range: 9-41). Tonometers were compared in pairs: slit-lamp GAT and Perkins, slit-lamp GAT and MSL GAT, and Perkins and MSL GAT. The pairwise Spearman rank correlations were 0.988, 0.988, and 0.983 (all P < 0.001). The mean differences in IOP (95% limits of agreement) were 0.5 (-0.6 to 1.6), 1.2 (0 to 2.4), and 0.7 (-0.7 to 2.1) mmHg, respectively.
Conclusion:
The MSL-mounted GAT provides reliable IOP readings with minor underestimation (within 2 mmHg in 88% of cases), suggesting its potential utility in clinical practice as a portable slit lamp and anterior segment imaging device.
