J Korean Ophthalmol Soc.  2019 Jul;60(7):627-634. 10.3341/jkos.2019.60.7.627.

Clinical Significance of Computerized Videokeratoscopic Indices for Dry Eye

• Lee JH
• Kim MH
• Ko BY

• KMID: 2453013
• DOI: http://doi.org/10.3341/jkos.2019.60.7.627

Abstract

PURPOSE
We evaluated the usefulness of the Tomey TMS-4Nâ„¢ computerized videokeratoscopy (Tomey, Nagoya, Japan) for dry eye by analyzing the correlation between the regularity indices of TMS-4Nâ„¢ and conventional dry eye parameters or dry eye severity.
METHODS
In this retrospective study, the medical records of 193 dry eye patients (386 eyes) were analyzed. The regularity indices of TMS-4Nâ„¢ such as the surface asymmetry index (SAI), surface regularity index (SRI), potential visual acuity (PVA), and irregular astigmatism index (IAI) were compared with conventional dry eye parameters (corrected visual acuity [CVA], ocular surface disease index [OSDI] score, tear film break-up time [TBUT], corneal staining score [CFS], and Schirmer's I test). We also analyzed correlations between the regularity indices of TMS-4Nâ„¢ and dry eye severity according to the Korean Corneal Disease Study Group.
RESULTS
The regularity indices of TMS-4Nâ„¢ such as SAI, SRI, PVA, and IAI increased according to the severity of dry eye. The regularity indices correlated significantly and positively with the CVA and CFS, but were significantly and negatively correlated with the TBUT. The OSDI score did not correlate with the regularity indices.
CONCLUSIONS
The regularity indices of TMS-4Nâ„¢ provide an objective method for follow-up as well as a means to measure the severity of dry eye disease.

Keyword

Dry eye; Regularity indices; Videokeratoscopy

MeSH Terms

Astigmatism
Corneal Diseases
Eye Diseases
Follow-Up Studies
Humans
Medical Records
Methods
Retrospective Studies
Tears
Visual Acuity

Figure

• 

  Figure 1 Examination images using Tomey TMS-4N™ (Tomey, Nagoya, Japan). The image is analyzed by a program which identifies the location of 256 circumferential points around each ring's reflection. CYL = simulated keratometric cylinder change; SRI = surface irregularity index; PVA = potential visual acuity; SAI = surface asymmetry index.

• 

  Figure 2 Indices from Klyce Corneal Statistics in Tomey TMS-4N™ (Tomey, Nagoya, Japan). Surface asymmetry index has measured the difference between the keratometry all ring 180 degrees apart across the corneal surface. Surface irregularity index measures the local variations in the corneal center. Potential visual acuity shows the visual acuity calculated by surface regularity index. Irregular astigmatism index measures the average sum of area corrected for the difference between each ring over the entire corneal surface. SAI = surface asymmetry index; SRI = surface irregularity index; CYL = simulated keratometric cylinder change; PVA = potential visual acuity; CVP = coefficient of variation of corneal power; ACP = average corneal power; SDP = standard deviation of corneal power; CEI = corneal eccentricity index; IAI = irregular astigmatism index; AA = analyzed area; EDP = elevation/depression power; EDD = elevation/depression diameter.

• 

  Figure 3 Differences and correlation between dry eye severity and videokeratoscopic regularity indices. Each videokeratoscopic index was positively correlated with severity of dry eye. Data were analyzed using one-way analysis of variance, Jonckheere-Terpstra test. SRI = surface regularity index; SAI = surface asymmetry index; PVA = potential visual acuity; IAI = irregular astigmatism index. *, o defined as a data point that is located outside the fence of the box plot (* = extreme values, o =out values).

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