Applanation tonometry: a comparison of the Perkins handheld and Goldmann slit lamp-mounted methods

Abstract

PurposeTo compare intraocular pressure (IOP) measurements, taken using Perkins applanation tonometry (PAT) and Goldmann applanation tonometry (GAT).Methods100 eyes of 100 patients underwent Perkins and Goldmann applanation tonometry, with a randomized order of modality, performed by a masked observer. The right eye was measured, for all subjects, and the data used in statistical analysis. The comparability of results given by the two instruments was evaluated using the Bland–Altman method.ResultsIOP measurements for 100 eyes were obtained (range: 10–44 mmHg). The mean GAT reading was 21.63 mmHg, with standard deviation (SD) 5.69 mmHg. The mean PAT reading was 21.40 mmHg, with SD 5.67 mmHg. The mean difference between readings from Goldmann versus Perkins tonometry was 0.22 mmHg (SD: 0.44 mmHg). The limits of agreement were calculated to be −0.64–+1.08 mmHg (1.96 SD either side of the bias).ConclusionThe Perkins applanation tonometer yields IOP measurements that are closely comparable with GAT. Therefore, PAT may be used in routine clinical practice, as part of the implementation of national guidelines, or preferred practice patterns, for glaucoma and ocular hypertension.

Tonometry

“…It is similar to the GAT in using a split-image device and fluorescein stained ocular surface. However, the values of IOP are not well correlated with that obtained by Goldmann tonometer [16]. Less common and more difficult to use…”

Diagnostic accuracy of the iCare rebound tonometer compared to the Perkins applanation tonometer in assessing intraocular pressure in rural patients

“…The Perkins applanation tonometer (PAT) is a handheld device (Figure 1) that is considered the handheld Goldmann tonometer [31]. The PAT is useful in patients who are obese, bedridden, and difficult to posture onto the slit lamp to be assessed by the GAT [32].…”

“…The PAT is useful in patients who are obese, bedridden, and difficult to posture onto the slit lamp to be assessed by the GAT [32]. Both GAT and PAT have various drawbacks such as the need for topical anesthesia of the eye and operation by an experienced user [31]. Corneal factors such as curvature, astigmatism, central corneal thickness also affect the accuracy of applanation tonometers [31].…”

“…Both GAT and PAT have various drawbacks such as the need for topical anesthesia of the eye and operation by an experienced user [31]. Corneal factors such as curvature, astigmatism, central corneal thickness also affect the accuracy of applanation tonometers [31]. The non-contact tonometer (NCT) (Figure 1) is often used as a screening tool to measure IOP, instead of using the GAT.…”

“…The non-contact tonometer (NCT) (Figure 1) is often used as a screening tool to measure IOP, instead of using the GAT. While the NCT is quick and non-invasive [31,33], it is not portable and costs range from $5000 to $22,000 depending on the type of machine. Thus, access to NCTs outside of professional eye care services is uncommon.…”