Original article
Foveal Cone Outer Segment Tips Line and Disruption Artifacts in Spectral-Domain Optical Coherence Tomographic Images of Normal Eyes

https://doi.org/10.1016/j.ajo.2011.08.021Get rights and content

Purpose

To determine the incidence of a continuous cone outer segment tips (COST) line at the fovea in spectral-domain optical coherence tomographic (SD-OCT) images of normal eyes.

Design

Prospective, interventional case series.

Methods

Forty-six right eyes of 46 normal individuals with visual acuities (VA) ≥20/20 were studied. SD-OCT images were obtained with a Cirrus HD-OCT instrument with both the standard 5-line raster and the high-definition (HD) 5-line raster scan modes. Images with signal strengths weaker than 5 (on a scale from 0 to 10) were excluded. The appearances of the COST line, photoreceptor inner segment/outer segment (IS/OS) junction, and external limiting membrane (ELM) line were determined in a masked way.

Results

The incidence of eyes with an intact foveal COST line was about 95%, and the incidence was not significantly associated with the age, sex, refractive error, signal strength, horizontal or vertical scans, and the use of either the standard or HD scans. Fragmented COST lines appeared to be attributable to blocking artifacts caused by a hyperreflectivity at the foveal surface because the COST fragmentation had corresponding fragmentation of the ELM and IS/OS junction lines. The correlation between a fragmented COST line and the hyperreflectivity on the retinal surface was significant for the vertical HD scans (P = .011) but not for the vertical standard, horizontal standard, or horizontal HD scans.

Conclusions

Commercial SD-OCT instruments can detect the COST line. Fragmentations of the COST lines in normal eyes are most likely artifacts caused by a parabolic reflection of a surface hyperreflectivity of the foveal pit.

Section snippets

Patients and Methods

Forty-six eyes of 46 healthy volunteers (19 men and 27 women) without any eye diseases were studied. The right eye of each subject was chosen arbitrarily to study. Each subject had a routine eye examination including measurements of the best-corrected visual acuity (BCVA) and intraocular pressure. All of the subjects had a BCVA of ≥20/20.

SD-OCT images were obtained by 6-mm scans with the Cirrus HD-OCT instrument (OCT 4000, Carl Zeiss Meditec, Dublin, California, USA) with both the standard

Results

The mean age of the subjects was 33.0 years with a range from 23 to 50 years. The mean decimal BCVA was 1.1 with a range from 1.0 to 1.5. The mean refractive error was −1.49 diopters (D) with a range from −8.0 to +3.25 D. The intraocular pressure ranged from 12 to 18 mm Hg. The mean signal strengths were 8.2 (horizontal standard scan), 8.3 (vertical standard scan), 8.3 (horizontal HD scan), and 8.3 (vertical HD scan); the range of signal strength was from 6 to 10.

In the SD-OCT images, the COST

Discussion

The correlations between the visual acuity and the integrity of the foveal COST line detected by commercial SD-OCT instruments has been reported to be significant in cases of occult macular dystrophy,16, 18 adult-onset foveomacular vitelliform dystrophy,17 macular hole,19 and central serous chorioretinopathy.20 Morphologic changes including an absence of the foveal COST line in the SD-OCT images have been reported to be correlated with the condition of the retina in eyes with retinal diseases.16

Tosho Rii a.k.a. Tong-Sheng Lee, MD, is currently an Instructor of Ophthalmology, Kyorin University Medical School, Tokyo, Japan. He received his MD from China Medical University, Taiwan, in 1997 and completed his ophthalmology residency at Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan. He gained laboratory research experiences in Taipei Medical University and Osaka University, and then joined the vitreo-retinal services of the Kyorin Eye Center in 2010. Dr Rii's research interest is in

References (28)

  • T. Otani et al.

    Correlation between visual acuity and foveal microstructural changes in diabetic macular edema

    Retina

    (2010)
  • T. Baba et al.

    Correlation of visual recovery and presence of photoreceptor inner/outer segment junction in optical coherence images after successful macular hole repair

    Retina

    (2008)
  • L.K. Chang et al.

    Disruption of the photoreceptor inner segment-outer segment junction in eyes with macular holes

    Retina

    (2008)
  • J.E. Lee et al.

    Reorganization of photoreceptor layer on optical coherence tomography concurrent with visual improvement after macular hole surgery

    Korean J Ophthalmol

    (2008)
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    Tosho Rii a.k.a. Tong-Sheng Lee, MD, is currently an Instructor of Ophthalmology, Kyorin University Medical School, Tokyo, Japan. He received his MD from China Medical University, Taiwan, in 1997 and completed his ophthalmology residency at Shin Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan. He gained laboratory research experiences in Taipei Medical University and Osaka University, and then joined the vitreo-retinal services of the Kyorin Eye Center in 2010. Dr Rii's research interest is in the pathophysiology and imaging of vitreoretinal diseases.

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