Abstract
Purpose: :
Our group has previously reported that sickle cell patients with focal macular thinning had significantly thinner retinal nerve fiber layer (RNFL) compared to those without macular thinning and controls on Heidelberg Spectralis spectral domain OCT (SD-OCT). The Heidelberg generates normative values based largely on a Caucasian population, which is known to have thinner RNFLs than patients of African descent. The aim of this study is to report the number of RNFL values that the Heidelberg Spectralis reports as abnormal (yellow or red) in our sickle cell patients, who are exclusively of African descent.
Methods: :
In this prospective study, SCH (SS, SC, and S-Thalassemia) patients and similar aged, race-matched controls underwent SD-OCT of the macula and optic nerve head (ONH) using the Heidelberg Spectralis. Patients with prior retinal treatments (laser or surgery), diabetes mellitus, glaucoma, or other ocular diseases were excluded. RNFL thickness measurements within each of the seven subfields of the ONH as displayed on the SDOCT report were recorded. The sickle patients were grouped into those with focal macular thinning and those without. The number of abnormal readings (yellow = <95 percentile or red = <99 percentile) that the Heidelberg generated in each group were recorded.
Results: :
151 eyes of 88 sickle patients and 57 eyes of 31 controls were included. In the macular thinning group (n= 81), 65 of 567 (11.5%) RNFL thickness values were marked as abnormal (yellow or red). In the no macular thinning group (n=70), 34 of 490 (6.9%) values were abnormal whereas in the control group (n=57), only 14 of 392 (3.5%) values were abnormal (Chi-square, p<0.0001, p<0.03 respectively). In the macular thinning group, there is a correlation between severity of macular thinning and frequency of RNFL abnormalities detected.
Conclusions: :
Up to 11% of the RNFL values in our sickle patient population were reported as abnormal by Heidelberg SD-OCT. When reading the RNFL report generated by Heidelberg SD-OCT, ophthalmologists should be aware that sickle cell patients may have thinner RNFL not related to glaucoma.
Keywords: vascular occlusion/vascular occlusive disease • imaging/image analysis: clinical • nerve fiber layer