title: Relationship between macular thickness measurement and signal strength using Stratus optical coherence tomography.
abstract: OBJECTIVE
  To examine the relationship between signal strength and macular thickness as measured by Stratus optical coherence tomography (OCT)'s fast macular thickness protocol in healthy subjects.
  
  
  METHODS
  In this prospective cross-sectional study 79 eyes of 42 healthy subjects were enrolled. The age, gender, and eye (right vs left) of each subject were recorded. The Stratus OCT fast macular thickness scan protocol was used and the macular thickness was measured with retinal thickness map analysis. Each eye was imaged at least six times to acquire images with signal strengths of 4, 5, 6, 7, 8, and 9 out of 10 via adjustment of the focusing knob. The OCT parameters included in the analysis were thickness in the central 1 mm and in the different quadrants in the 3-mm area.
  
  
  RESULTS
  Overall 79 eyes of 42 patients with a mean age of 38.4±12.4 were included. There was no significant difference between the signal strength measurements obtained with different signal strengths in the central thickness (P=0.20). In the superior, nasal, inferior, and temporal quadrants, a signal strength of 8 demonstrated up to 3 µm thicker measurements than a signal strength of 5 (P<0.05). In general linear regression analysis, after accounting for age and gender, signal strength did not remain a significant predictor of thickness in any quadrant.
  
  
  CONCLUSIONS
  When using fast map macular measurements, a signal strength of 5 is clinically as efficient as a signal strength of 8 in measuring macular thickness in all quadrants. Insisting on higher signal strength may not be necessary.
authors.affiliation: Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel and the Sackler School of Medicine, Tel Aviv University, Tel Aviv.
authors.forename: Ori
authors.initials: O
authors.lastname: Segal
authors.affiliation: Department of Ophthalmology, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Yinon
authors.initials: Y
authors.lastname: Shapira
authors.affiliation: Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel and the Sackler School of Medicine, Tel Aviv University, Tel Aviv.
authors.forename: Assaf
authors.initials: A
authors.lastname: Gershoni
authors.affiliation: Department of Ophthalmology, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Igor
authors.initials: I
authors.lastname: Vainer
authors.affiliation: Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel and the Sackler School of Medicine, Tel Aviv University, Tel Aviv.
authors.forename: Arie Y
authors.initials: AY
authors.lastname: Nemet
authors.affiliation: Department of Ophthalmology, Meir Medical Center, Kfar Saba, Israel and the Sackler School of Medicine, Tel Aviv University, Tel Aviv.
authors.forename: Noa
authors.initials: N
authors.lastname: Geffen
authors.affiliation: Department of Ophthalmology, Rambam Health Care Campus, Haifa, Israel.
authors.forename: Michael
authors.initials: M
authors.lastname: Mimouni
keywords: Stratus OCT; fast map macular measurement; macular thickness; retinal thickness; signal strength