J Korean Ophthalmol Soc.  2008 Apr;49(4):577-582. 10.3341/jkos.2008.49.4.577.

Intraocular Pressure Measurements Using Dynamic Contour Tonometer After Photorefractive Keratectomy

• Choi HJ
• Kim SW
• Kim TI
• Kim EK

• KMID: 2211487
• DOI: http://doi.org/10.3341/jkos.2008.49.4.577

Abstract

PURPOSE: To assess the performance of the dynamic contour tonometer (DCT) in eyes undergoing excimer laser photorefractive keratectomy (PRK).
METHODS
Intraocular pressure (IOP) was measured in 30 eyes after first time excimer laser PRK pre and three months post operatively using Goldmann applanation tonometer (GAT), noncontact air tonometer (NCT), and the DCT.
RESULTS
There was significant correlation between central corneal thickness (CCT) and IOP measurements by GAT and NCT (CCT vs GAT: r2=0.31, p<0.01, CCT vs NCT: r2=0.39, p<0.01). However, the correlation between CCT and IOP measurements by DCT was not significant (CCT vs DCT: r2=0.14, p=0.32). After PRK, the mean change in CCT and IOP measurements using GAT, NCT, DCT were 73.70+/-26.92 micrometer (mean+/-SD), 2.43+/-2.86 mmHg (p<0.01), 3.83+/-2.34 mmHg (p<0.01) and 0.44+/-1.51 mmHg (p=0.125), respectively. The preoperative and postoperative DCT measurements did not differ significantly.
CONCLUSIONS
The reduction in CCT induced by PRK doesn't appear to influence DCT measurements; therefore, DCT may be better suited over GAT or NCT for monitoring IOP in eyes that underwent refractive surgery.

Keyword

Central corneal thickness; Pascal dynamic contour tonometer; Photorefractive keratectomy

MeSH Terms

Eye
Intraocular Pressure
Lasers, Excimer
Peptides
Photorefractive Keratectomy
Refractive Surgical Procedures
Peptides

Figure

• 

  Figure 1. Pre- and post-PRK IOP measurements by GAT, NCT, and DCT (mean±SD). The decrease in GAT and NCT measurements after PRK was statistically significant (* † p<0.01). The DCT measurements preoperatively p<0.01, and postoperatively did not differ significantly (‡ p=0.125). Box plots of median (center line), 25th and 75th percentile values (bottom and top lines) and range of values (brackets); PRK=photorefractive keratectomy; IOP=intraocular pressure; CCT=central corneal thickness; GAT=Goldmann applanation tonometric intraocular pressure; NCT=non-contact tonometric intraocular pressure; DCT=dynamic contour tonometric intraocular pressure.

• 

  Figure 2. Correlation between changes in IOP readings and reduction of CCT after PRK as measured by GAT, NCT and DCT. Most of the DCT values lay within ±2 mm Hg from the preoperative baseline values, whereas most change of GAT and NCT lay below this boundary, indicating an underestimation of IOP in the treated eye; PRK= photorefractive keratectomy; IOP=intraocular pressure; CCT= central corneal thickness; GAT=Goldmann applanation tonometric intraocular pressure; NCT=non‐ contact tonometric intraocular pressure; DCT=dynamic contour tonometric intraocular pressure.

• 

  Figure 3. Correlation of tonometer readings with CCT. The IOP measurements by GAT and NCT were significantly affected by CCT (GAT vs CCT; r2=0.31, p<0.01, y=0.027×-1.662, NCT vs CCT; r2=0.39, p<0.01, y=0.044× −10.32). The IOP measurements by DCT were not statistically affected by CCT (r2=0.029, p=0.195, y=-0.008x+20.79); IOP= intraocular pressure; CCT=central corneal thickness; GAT= Goldmann applanation tonometric intraocular pressure; NCT= non-contact tonometric intraocular pressure; DCT=dynamic contour tonometric intraocular pressure.

Reference

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