J Korean Ophthalmol Soc.  2016 Feb;57(2):248-255. 10.3341/jkos.2016.57.2.248.

Comparison of Image Quality between Swept-Source and Spectral-Domain Optical Coherence Tomography According to Ocular Media Opacity

• Hong EH
• Park SH
• Lee JW
• Lee JH
• Song IS
• Lee BR

• KMID: 2213666
• DOI: http://doi.org/10.3341/jkos.2016.57.2.248

Abstract

PURPOSE
To compare the image quality between swept-source optical coherence tomography (SS-OCT) and spectral domain optical coherence tomography (SD-OCT), especially in eyes with media opacity.
METHODS
Forty eyes without media opacity and 60 eyes with media opacity (30 eyes with cataract, 20 eyes with vitreous opacity, and 10 eyes with corneal opacity) were included in this study. SD-OCT and SS-OCT 6 x 6 macular scans were taken by a single operator. For image quality analysis, a total of 200 OCT images were subjectively graded by two trained retina specialists and measured quantitatively using the image quality factor (QF) built into the OCT devices.
RESULTS
Compared to conventional SD-OCT, SS-OCT had statistically significantly better subjective and objective grades in the normal group, as well as each of the media opacity groups (p-value < 0.001). In both the subjective and objective grades, there was no significant difference according to the types of media opacity (QF: p = 0.188, subject grading scale [SGS]: p = 0.635) and the degree of media opacity (Group I: 20 < or = QF < 50, Group II: 0 < or = QF < 20; QF: p = 0.088, SGS: p = 0.051) in the superiority of image quality of SS-OCT to SD-OCT.
CONCLUSIONS
In this media opacity patient population, swept-source OCT is a superior diagnostic tool when compared with SD-OCT in both objective and subjective assessments, even in the ocular media opacity. This result may be useful in diagnosis and progression detection of retinal disease in media opacity eyes.

Keyword

Image quality; Ocular media opacity; Swept source optical coherence tomography

MeSH Terms

Cataract
Diagnosis
Humans
Retina
Retinal Diseases
Specialization
Tomography, Optical Coherence*

Figure

• 

  Figure 1. A representative OCT b-scan image showing how to grade subject grading scale (SGS). The graded OCT features were labeled (a) vitreous, (b) vitreo-retinal interface, (c) nerve fiber layer, (d) ganglion cell layer, (e) plexiform layers, (f) outer nuclear layer, (g) outer limiting membrane, (h) outer ret-ino-choroidal complex, (i) choroidal/scleral interface. Question 1 in the subjective grading scheme corresponds to the intensity difference between features a and h; question 2, visibility of b; question 3, intensity difference between a and c; question 4, intensity difference between a and e; question 5, visibility of multiple layers within h; question 6, visibility of d (against c and e); question 7, intensity difference between a and f; question 8, visibility of g; and question 9, visibility of i. Figure revised from Huang et al.11 OCT = optical coherence tomography.

• 

  Figure 2. Representative cases of ocular media opacity. (A-C) A case of corneal opacity. Anterior segment photograph shows dense central corneal opacity (A). After dilating of pupil, SS-OCT and SD-OCT images were obtained. The b-scan image of SS-OCT shows relatively clear borders of each retinal layers and visualizes choroidal/scleral interface clearly (B), but in SD-OCT image, the borders of each layer are obscure and choroidal/scleral interface is not shown (C). (D-F) A case of cataract (lens opacity). Anterior segment photograph shows severe nuclear and cortical cataract (D). In the b-scan image of SS-OCT, each layers of retina are vi-sualized (E). The b-scan image of SD-OCT could not visualize the layers (F). (G-I) A case of vitreous hemorrhage (vitreous opacity). In the fundus photograph, vitreous hemorrhage is shown and the fundus looks hazy (G). The b-scan image of SS-OCT (H) shows relatively clear view of each layers of retina and choroidal/scleral interface than the b-scan image of SD-OCT (I). SD-OCT = spectral domain optical coherence tomography; SS-OCT = swept-source optical coherence tomography.

• 

  Figure 3. Image quality of SD-OCT and SS-OCT in normal and each ocular media opacity groups. (A) Comparison of objective quality parameter (quality factor, QF) of SD-OCT and SS-OCT according to type of ocular media opacity. (B) Comparison of subjective quality parameter (subjective grading scale, SGS) of SD-OCT and SS-OCT according to type of ocular media opacity. SD-OCT = spectral domain optical coherence tomography; SS-OCT = swept-source optical coherence tomography.

• 

  Figure 4. Image quality of SD-OCT and SS-OCT in each severity groups of ocular media opacity. (A) Comparison of objective quality parameter (quality factor, QF) of SD-OCT and SS-OCT according to degree of ocular media opacity. (B) Comparison of subjective quality parameter (subjective grading scale, SGS) of SD-OCT and SS-OCT according to degree of ocular media opacity. SD-OCT = spectral domain optical coherence tomography; SS-OCT = swept-source optical coherence tomography.

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