Abstract
Purpose::
To compare four different methods of measuring central corneal thickness (CCT) and corneal opacities thickness (COT). Patients and
Methods::
Consecutive cases series study of patients with chronic adenoviral corneal opacities and visual acuity worse than 20/40, previously treated with corticosteroids without success, were submitted to four different devices: ultrasound pachymeter (US), ultrasound biomicroscopy (UBM), Scheimpflug System (SS) Pentacam® and coherence optical tomography (OCT) Visante®, and results were compared.
Results::
Twenty-four eyes of 19 patients (5 were bilateral), 11(57,8%)were women, mean age was 40 years old (range18-65). Time of visual disturbance duration was 21+/-16 months (range 4-48). CCT and COT were determined with the different modalities (mean+/- standard deviation), US: 512+/- 39 microm (µm); UBM: 500.9+/-31,4 µm and 165 +/- 59.9 µm; SS: 496+/-45.4 µm and 168.2 +/- 32.8 µm; OCT : 513+/-39,8 µm and 140.8 +/- 22.6 µm. Higher correlation was found in all methods for CCT (r = 0,796 to 0,933) p<0.01. Mean differences between UBM and SS for CCT was 2,85 µm (95% limits of agreement were: -10,24 to 15,94 µm) p= 0,654 , for COT: -2,39 µm (-26,15 to 21,36 µm ) p= 0,836. Between UBM and OCT for CCT: -12,38 µm (-23,51 to -1,24µm ) p= 0,031 and COT: 23,24 µm (-2,99 to 49,46 µm) p= 0,08. Comparing SS and OCT, CCT was: -14,04 µm (-23,47 to -4,61µm) p=0,006 and COT: 27,40 µm (8,89 a 45,9 µm) p=0,006. For COT: moderate correlation was found between UBM and SS: r = 0,423 (p= 0,045); poor correlation was found between UBM and OCT: r =0,159 (p= 0,469) and when comparing SS and OCT; r = -0,224 (p= 0,293).
Conclusions::
In the assessment of abnormal corneas, such as adenoviral nummular infiltrates, positive correlation decreased when comparing COT evaluation with SS, OCT, UBM. In all methods CCT was highly correlated, SS and OCT were more correlated to US and UBM presented underestimated values.