Abstract
Purpose::
To compare the diagnostic assessment of optic nerve head (ONH) by indirect ophthalmoscopy and HRT III in patients with retinitis pigmentosa.
Methods::
This study included 46 eyes of 27 patients with diagnosis of retinitis pigmentosa. An expert evaluator (kappa = 0.82) addressed optic nerve head (ONH) pallor and vertical cup/disc ratio (C/D) by means of slit-lamp indirect ophthalmoscopy (IO); ONH HRT (performed by a single operator, kappa = 0.90) was also performed. ONH were divided in normal (16/46) and pale (30/46) based on ophthalmoscopic appearance; for each group, C/D values obtained by IO and HRT were compared by means of t-test. HRT image quality, defined as standard deviation (SD), was also addressed. Difference in results was analysed by means of regression analysis.
Results::
C/D for patients with normal discs was 0.30 ± 0.11 with IO and 0.30 ± 0.23 with HRT (P=0.95, R-square = 0.40). In the group with pale ONH a difference of 0.18 was found (IO, 0.34 ± 0.14; HRT, 0.53 ± 0.24, P=0.0006), with a poor correlation between the two techniques (R-square = 0.18). SD of HRT images was significantly higher in normal than pale ONH (P=0.007) and it was a positive predictor for high difference in C/D evaluation by the two techniques (P = 0.0076, regression analysis).
Conclusions::
For normal ONH, C/D evaluation by IO and HRT was very similar. On the other hand, a significant difference between the two techniques was found in the group with pale ONH. This could be due to lower image quality in more severe stages of the disease and/or also to an abnormal reflectance of pale discs, which would increase the difficulty of HRT assessment.
Keywords: degenerations/dystrophies • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc