Table 3:
Objective Quantification Methods of Ocular Redness
| Group | Description | Region of Interest (ROI) | Characteristics | Limitations |
|---|---|---|---|---|
| Willingham FF et al | Mean relative redness (RR) Blood vessel area ratio (VA) | Temporal and nasal bulbar (circle region) | Reduce the impact of operator in consistency during image acquisition | Need specific camera and image system |
| Owen CG et al | Proportion of vasculature | Temporal bulbar (square region) | Distinguish vasculature between conjunctivae and sclera, increase sensitivity | ROI was not the same area among the subjects. |
| Guillon M et al | Individual vessel width Percentage vessel coverage |
All four quadrants of limbal and bulbar | Provide a precise and sufficient sensitive measure of the level of conjunctival redness | Not relate closely to the subjective measurements. |
| Sorbara L et al | CIEu* chromaticity values (0–107 (deep red)) | Temporal and nasal bulbar (circle region) | Offer accurate and more sensitive measurements of redness | Not variable at low levels of ocular redness |
| Yoneda T et al | Proportion of blood vessels in the conjunctiva | Temporal bulbar (square region) | Simple analysis and images can be analyzed promptly | All photographs were taken by a single photographer and not reliable |
| Amparo F et al | Ocular redness index (ORI): a continuous centesimal (0–100) scale | Whole temporal bulbar(freehand selection) | Intuitive, efficient and user friendly | The way of white balance affects final scores a lot |
| Fieguth P et al | Edge-Redness Assessed Grade (0–100) | Whole temporal and nasal bulbar | Minimum amount of operator intervention, more accuracy and less variability | Need more time and too complicated |
| Ferrari G et al | Relative redness of image (RRI) Edge feature (EF) scales |
Freehand selection around the exposed conjunctiva | A semiautomatic method to objectively quantify ocular surface inflammation in a simple and low cost way | Long time required to process images |
| Wolffsohn JS et al | Edge detection (ED) Relative color extraction (RCE) |
Temporal bulbar (rectangular region) | More sensitive and reliable than subjective grading. | Non-linear scale |
| Park IK et al | Occupied area by blood vessels | Whole temporal bulbar(freehand selection) | Cover the whole range of conditions that may cause conjunctival injection with various severity levels, not limited to specific conditions | Complicate algorithms need to be applied |
| Rodriguez JD et al | Total average redness intensity (Com-Red) Proportion of horizontal conjunctival vessels (Com-Hor) |
Temporal bulbar (rectangular region) | Objective measurement of the geometry of vessels | Only proved in Dry eye Disease induced ocular redness |
| Wu et al | Redness score (RS):Area percentage ratio between the vessels and the remainder of analyzed area | Nasal limbal, temporal limbal, nasal bulbar, temporal bulbar and global | A reliable and objective commercial product that can be used easily | Machine restricts the visible ocular area, overestimated the scores obtained using the subjective scale |
| Romano V et al | Pixel densitometry index (PDI): The mean intensity of the pixels in the ROI | Nasal, temporal, superior, and inferior conjunctival quadrant. | Avoid the need for white balance standardization of a photograph | Invasive measurement and PDI cannot be as amenable to interpatient comparison |