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CS de Paiva, JL Lindsey, SC Pflugfelder; Assessing the Severity of Keratitis Sicca with Videokeratoscopic Indices . Invest. Ophthalmol. Vis. Sci. 2002;43(13):3892.
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Purpose: To determine the correlation between the regularity indices of the Tomey TMS-2N videokeratoscopy instrument with conventional measures of tear film stability and dry eye symptoms. Methods: The surface regularity index (SRI), surface asymmetry index (SAI), potential visual acuity index (PVA) and irregular astigmatism index (IAI) of the Tomey TMS-2N were compared between 16 eyes of 16 normal subjects and 74 eyes of 74 dry eye patients. We studied the correlations between these indices and the symptom severity questionaire score, Schirmer 1 test, meibomian gland evaluation (with a composite " MGD" score), tear break up time (TBUT), and corneal fluorescein staining score. Results: The mean standard deviation ( SD) age was significantly lower in the normal subjects (37.5 16.22) than in the dry eye patients (58.55 15.73 , P<0.0001). The mean best corrected visual acuity (BCVA) was similar in both groups. Dry eye patients had greater mean symptom severity scores, lower Schirmer 1 test scores, greater MGD scores, more rapid TBUT and greater total corneal fluorescein staining scores (P<0.001 for all parameters).The SRI, SAI and IAI were all significantly greater in dry eye patients than normal subjects. These were 0.460.36 (normal) versus 1.090.76 (dry eye) for the SRI (P=0.0017), 0.300.15 (normal) versus 0.901.09 (dry eye) for the SAI (P=0.0321), and 0.420.28 (normal) versus 0.560.24 (dry eye) for the IAI (P=0.0321). The PVA index was significantly lower in the dry eye (0.890.13) than normal eyes (0.68 0.23) (P=0.0008). The SRI, SAI and IAI were positively correlated with total and central corneal fluorescein staining scores (P<0.00001 for all indices). An SRI (≥ 0.80), the SAI (≥0.50) and the IAI (≥ 0.50) had a sensitivities in predicting total corneal fluorescein staining (score ≥ 3) of 89%, 69% and 82%, respectively. The specificity of these indices was 80%, 78% and 82%, respectively. In all 90 eyes, the mean SRI was significantly elevated in subjects older than 50 years (P= 0.012), compared to younger patients, while no age effect was noted in the dry eye patients. Conclusion: Patients with dry eye have an irregular corneal surface that may contribute to their irritation and visual complaints. Because of their high sensitivity and specificity, the regularity indices of the Tomey TMS-2N have the potential to be used as objective diagnostic indices for dry eye, as well as a means to evaluate the severity of this disease.
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