Intraocular Pressure Variation by Pneumatic Tonometer Before and After Phacoemulsification
Condition: Intraocular Pressure; Cataracts Senile
MeSH terms: Cataract
Study type: Observational

Summary: 
      The objective of this study is to evaluate the IOP variation before and 30 days after
      performing phacoemulsification through pneumatic tonometry, in addition to evaluating the
      factors possibly related to this variation.
    

Detailed description: 
      Cataracts represent the major cause of treatable blindness in developing countries. According
      to data , there are 45 million blind people in the world, of which 40% is due to cataract
      etiology. In Brazil, there are about 350,000 individuals blinded by cataracts.

      One of the consequences observed after the cataract surgery is the variation of intraocular
      pressure (IOP). IOP is directly related to the volume of aqueous humor in the anterior
      chamber. Reports of oscillations after a cataract surgery range from +1.3 to -2.5 mmHg. The
      duration of this oscillation varies according to the literature studied. Some studies show
      that the oscillation seen in the first postoperative year was maintained for the 10-year
      period and was similar in patients of all ages. However, other authors have identified a
      non-permanent oscillation, which makes this topic controversial in ophthalmology.

      There are a number of factors related to the degree of IOP reduction after a cataract
      surgery. Studies have shown that the preoperative IOP value, the depth of the anterior
      chamber, the volume of irrigation used during surgery and the age of the patients may
      interfere with the IOP variation in the postoperative period.

      However, the gold standard tonometer for IOP measurement is Goldmann's. This measurement is
      closely related to important characteristics of the cornea, such as its thickness and
      curvature, and may underestimate or overestimate IOP values.

      Another way to measure IOP is through a non-contact tonometer, blow or pneumatic. The blow
      tonometer has a pneumatic system that produces a jet of air, which leads to flattening of the
      cornea and on the surface of which a beam of parallel light rays is projected, in which only
      the reflected parallel and coaxial rays are picked up by the receiver of the device,
      obtaining a maximum peak of light reception when the cornea is flattened. Its main advantage
      is in its use in screening programs, the need for the use of eye drops and the lowest rates
      of contamination. The blow tonometer, as well as the flattening tonometer, is influenced by
      corneal factors, such as curvature and thickness, presenting the same parameters of under and
      overestimation of IOP.

      The objective of this study is to evaluate the IOP variation before and 30 days after
      performing phacoemulsification through pneumatic tonometry, in addition to evaluating the
      factors possibly related to this variation.
    

Time perspective: Cross-Sectional
Sampling method: Probability Sample
Study population: 
        People with cataract and with good systemic health
      
Keywords: intraocular pressure; phacoemulsification; cataract