Clinical estimation of intraocular pressure with a non-contact tonometer and Goldman applanation tonometer as a tool for mass screening and its correlation with central corneal thickness: A comparative hospital based study Orginal Articles

Anshulee Sood, Arshi Nazir, Farooq Runyal, Sajad Mohiudin, Tania Sadiq
2015 GJMEDPH   unpublished
Purpose To assess the mean difference between intra-ocular pressure measurement by Goldmann applanation tonometer and Non Contact tonometer to determine the suitability of tonometer for community or mass screening and the variation in intra-ocular pressure between the two devices with respect to CCT. Material and Methods The proposed study was conducted on 300 eyes of 150 patients. The IOP assessment with the Goldmann applanation tonometer was always subsequent to that with the air-puff
more » ... he air-puff noncontact tonometer (AT-555). An average of three readings taken 15 seconds apart, with each method was taken to get final intraocular pressure reading for each eye. The central corneal thickness (CCT) measurements were performed using the pachymeter. Results Majority of the eyes were found to be in the 12-24 mmHg group i.e. 51 % eyes in the right eye and 64 % in the left eye. 3. Mean IOP measured with NCT was 22.30±10.149 mmHg and with GAT was 18.31±7.427 mmHg, thus showing a difference of 3.99 mmHg. In patients where IOP was <12mmHg the first group (G1), the mean difference was 1.28mm Hg in right eye and 1.63mmHg in left eye(p=0.006). In patients with IOP 12-24 mmHg mean IOP difference in right eye was 2.28mmHg and in left eye was 4.24mmHg (p<0.001). In patients with IOP >24mm Hg the difference in the mean IOP for right eye was 5.69mmHg and for left eye 7.84mmHg (p<0.001). Both the methods of IOP measurement showed positive correlation with central corneal thickness. The NCT was more influenced by CCT than GAT; for every 10 micron CCT change, the IOP change expected with NCT was 0.47 mmHg and GAT was 0.29 mmHg. Conclusion Thus we can conclude that NCT can be used as a screening procedure in tertiary care centres catering to a large number of patients wherein it is not possible to do Goldmann applanation tonometry on all patients.. However, intraocular pressure readings may require adjustment, especially when measured with NCT in those patients who have a CCT that is significantly different from population mean.