Effect of Manual Eyelid Manipulation on Intraocular Pressure Measurement by Rebound Tonometry

Abstract

Purpose : To investigate the effect of eyelid manipulation on the measurement of intraocular pressure (IOP) using two different tonometers (Rebound tonometry [RT] vs. Goldmann applanation tonometer [GAT])

Methods : One hundred and three (103) primary open-angle glaucoma (POAG) patients were prospectively enrolled. For all of the patients, IOP measurements were performed in three different ways (figure 1): (1) RT withlid manipulation (LM). (2) RT without LM, and (3) GAT. The order of the three measurements was randomly selected. Additionally, the palpebral fissure height (PFH; elliptic space between upper and lower eyelids) were measured.

Results : The mean value of IOP measured by GAT was 13.97 ± 2.80 mmHg, which was not significantly different from that by RT without LM (13.75 ± 2.44 mmHg; P = 0.096), but which was significantly lower than that by RT with LM (15.21 ± 2.91 mmHg; P <0.001). On a Bland-Altman plot, RT with LM was overestimated relative to GAT (mean: -1.5) and RT without LM (mean: -1.2). Among the high IOPs (>20 mmHg), interestingly, those measured by RT without LM were significantly lower than those measured by GAT (P <0.001). In the subgroup analysis of PFH, the smaller the PFH, the more exaggerated the IOP difference between GAT (P = 0.014) and RT with LM (P <0.001) (figure 2).

Conclusions : Rebound tonometry (RT)-measured IOP was significantly exaggerated when manipulation was applied to the eyelid. This overall trend was more pronounced when PFH was small. GAT-measured IOP, meanwhile, showed a good correlation with IOP measured using RT without LM.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Figure 1. Three IOP measurement modalities
(A) RT without LM, by which the examiner does not touch the eyelid. (B) RT with LM, by which the examiner opens the eyelids manually and compresses the eyeball, also manually. (C) GAT, a common form of applanation tonometry by which IOP is measured with (if required) or without eyelid manipulation

 

Figure 2. Subgroup analysis of PFH for each IOP measurement
The PFH measurements of the total study population were divided into small (< 7 mm, n= 34) moderate (7 ~ 8 mm, n=45) and large (> 8 mm, n=24) subgroups. For each of the 3 modalities of IOP measurement, changes in IOP according to the three PFH subgroups were analyzed.