Intraocular pressure measurement after pars plana vitrectomy

Area of Science:

• Ophthalmology
• Biomedical Engineering

Background:

• Accurate intraocular pressure (IOP) measurement is crucial for managing glaucoma and other ocular conditions.
• Pars plana vitrectomy is a common surgical procedure that can affect IOP readings.
• The presence of intravitreal gas after vitrectomy can significantly alter IOP measurements.

Purpose of the Study:

• To evaluate the accuracy of different tonometers for measuring IOP after pars plana vitrectomy.
• To compare the performance of Schiøtz, Goldmann, and Digilab pneumatic tonometers in eyes with and without intravitreal gas post-vitrectomy.

Main Methods:

• Prospective study involving 47 eyes undergoing pars plana vitrectomy.
• IOP measurements were taken using Schiøtz, Goldmann, and Digilab tonometers before and after surgery.
• Eyes were categorized based on the presence or absence of intravitreal gas on postoperative day one.

Main Results:

• The Schiøtz tonometer significantly underestimated Goldmann IOP in eyes with intravitreal gas (35%) and without gas (13%).
• The Digilab tonometer showed minimal underestimation compared to Goldmann IOP, even in the presence of intravitreal gas (18% with gas, 7% without gas).
• No significant underestimation (>10 mmHg) by the Digilab tonometer was observed postoperatively.

Conclusions:

• The Schiøtz tonometer is unreliable for measuring IOP after pars plana vitrectomy, particularly when intravitreal gas is present.
• The Digilab pneumatic tonometer provides a more accurate and reliable measurement of IOP in the post-vitrectomy setting, including eyes with intravitreal gas.
• Clinical decisions regarding IOP management after vitrectomy should consider the limitations of certain tonometer types.