Hra spectralis viewing module

OCT macular cube scans (61 B-scans covering an area of 30° × 25°) were acquired with Spectralis SD-OCT (Heidelberg Engineering, Heidelberg, Germany), as previously described.²⁶ (link)^,27 (link) Scans with significant artifacts or signal strength of lower than 15 dB were excluded. Scans were automatically segmented into each individual retinal layer using the HRA/Spectralis Viewing Module (Heidelberg Engineering). The GCL was reviewed (Fig. 1A) in all scans and manually corrected if necessary. GCL thickness was then extracted from across the macula as 64 measurements within an 8 × 8 grid centered on the fovea (each grid location covering 0.74 mm² [approximately 3° × 3°]; Fig. 1B). For scans where manual correction was not possible, grid locations were excluded from the analysis. If an eye had >10% of grid locations missing, the eye was excluded from the analysis.²⁷ (link)

Clinical examination included bilateral CDVA testing at standardized light conditions, biomicroscopy, tonometry and examination of the fundus. The classification for very low VA was on a semi-quantitative scale such as hand motion (HM) and counting fingers (CF). For statistical purposes, the Snellen values were transformed to the equivalent LogMAR units. The very low VA measurements were converted as follows: HM 2.3 and CF 1.9 LogMAR (17 (link)). Central retinal thickness (CRT) and the existence of intraretinal fluid (IRF) and subretinal fluid (SRF), pigment epithelial detachment (PED), subretinal fibrosis and geographic atrophy (GA) was recorded by spectral-domain optical coherence tomography (SD-OCT; Heidelberg Eye Explorer Version 1.9.10.0 and HRA/SPECTRALIS^® Viewing Module Version 6.0.9.0, Heidelberg Engineering GmbH, Heidelberg, Germany).
The type and severity of cataract were graded according to the WHO simplified cataract grading system to three levels reflecting progressive severity (18 (link)). The grading was performed preoperatively by a single surgeon.