Abstract
Purpose :
HbSS patients have less severe proliferative retinopathy but more severe systemic complications compared to HbSC patients. We previously shown mean macula thickness to be lower in HbSS patients compared to HbSC patients based on a small cohort of 41 eyes. We have extended the study here to include 380 eyes to confirm if there is a real difference in macula thickness between HbSS and HBSC patients.
Methods :
A list of HbSC and HbSS patients seen in the eye clinic at St Thomas Hospital was generated. 197 HbSC eyes and 183 HbSS eyes from 204 patients were included. Eyes with other ocular pathologies that affected macula thickness were excluded. The latest macula OCT were retrospectively analysed. Macula thickness were recorded in all subfields of the ‘early treatment of diabetic retinopathy study ‘ (ETDRS) grid for both right and left eyes. The thickness measured were compared between HbSS and HbSC eyes. 99 HbSC right eyes were compared with 90 HbSS right eyes. 98 HBSC left eyes were compared with 93 HbSS left eyes. Analysis of right and left eyes were not combined. Unpaired t-test was used to verify the significance of the results.
Results :
The mean age (SD) was 42 (13) and 36(11) for HbSC and HBSS patients respectively. Macula thickness was lower in HBSS eyes compared to HbSC eyes in all subfields of the EDTRS grid but only reached significance at p value of <0.05 in the outer temporal subfields. This statistically significant difference was found in both right and left eyes. The mean outer temporal macula thickness (SD) was 240 (23) microns in HbSC right eyes compared with 231 (26) microns in HbSS right eyes and 242 (21) microns in HbSC left eyes compared with 234 (26) microns in HbSS left eyes. Table 1 and 2 compared the macula thickness of all the other subfields on the EDTRS grid.
Conclusions :
HbSS eyes have thinner outer temporal macula compared to HbSC eyes. This is likely due to greater retinal ischaemia caused by sickling in HbSS eyes compared to HbSC eyes. This is in contrast to more advanced proliferative sickle retinopathy in HBSC eyes compared to HBSS shown in other studies.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.