Goldmann applanation tonometer versus ocular response analyzer for measuring intraocular pressure after congenital
Sepehr Feizi1, Amir Faramarzi1, Bahareh Kheiri1
1Ophthalmic Research Center, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Purpose:
To compare intraocular pressure measured using the Goldmann applanation tonometer with that measured using the ocular response analyzer after congenital cataract surgery.
Methods:
This study included 113 eyes of 64 patients who underwent lensectomy and vitrectomy. In all, 36 eyes remained aphakic after surgery. Intraocular lens implantation was performed at the time of surgery in 47 eyes and secondarily in 30 eyes. Corneal hysteresis, corneal resistance factor, and cornea-compensated intraocular pressure were measured. The influences of independent factors on the difference between the cornea-compensated intraocular pressure and intraocular pressure measured with Goldmann applanation tonometer were investigated using linear regression analyses. Agreement between the two tonometers was investigated using the Bland and Altman and 95% limits of agreement analysis.
Results:
Central corneal thickness, corneal hysteresis, and corneal resistance factor were 591.2 ± 53.3 µm, 10.83 ± 2.27 mmHg, and 11.36 ± 2.14 mmHg, respectively. Cornea-compensated intraocular pressure (16.75 ± 4.82 mmHg) was significantly higher than intraocular pressure measured with Goldmann applanation tonometer (14.41 ± 2.27 mmHg, p < 0.001). Central corneal thickness (p = 0.02) and corneal hysteresis (p < 0.001) were identified as the main predictors of difference between cornea-compensated intraocular pressure and intraocular pressure measured with Goldmann applanation tonometer readings. A 95% limits of agreement for cornea-compensated intraocular pressure and intraocular pressure measured with Goldmann applanation tonometer was between -4.86 and 9.53 mmHg in the entire group. Cornea-compensated intraocular pressure showed the best agreement with intraocular pressure measured with Goldmann applanation tonometer in the primary pseudophakic subgroup as compared to the other subgroups.
Conclusion:
The Goldmann applanation tonometer and ocular response analyzer cannot be used interchangeably for measuring intraocular pressure after congenital cataract surgery. The difference between the cornea-compensated intraocular pressure and intraocular pressure measured with Goldmann applanation tonometer was primarily affected by central corneal thickness and corneal hysteresis. Among the subgroups, the primary pseudophakic subgroup had the thinnest cornea and the highest corneal hysteresis values and demonstrated the best agreement between the two tonometers.
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