Corneal surface regularity and the effect of artificial tears in aqueous tear deficiency

Citation
Zg. Liu et Sc. Pflugfelder, Corneal surface regularity and the effect of artificial tears in aqueous tear deficiency, OPHTHALMOL, 106(5), 1999, pp. 939-943
Citations number
18
Categorie Soggetti
Optalmology,"da verificare
Journal title
OPHTHALMOLOGY
ISSN journal
01616420 → ACNP
Volume
106
Issue
5
Year of publication
1999
Pages
939 - 943
Database
ISI
SICI code
0161-6420(199905)106:5<939:CSRATE>2.0.ZU;2-7
Abstract
Purpose: To evaluate corneal surface regularity and the effect of artificia l tears on the regularity of the corneal surface in dry eye. Design: A prospective, clinic-based, case-control study. Participants: A total of 64 eyes of 33 normal subjects and 42 eyes of 22 pa tients with aqueous tear deficiency were evaluated. Methods: Indices of the TMS-I corneal topography instrument (Tomey Technolo gy, Cambridge, MA) were used to evaluate corneal surface regularity and pot ential visual acuity (PVA) in patients with aqueous tear deficiency dry eye before and after the instillation of artificial tears and in normal subjec ts. The TMS-I topographic maps were classified into round, oval, symmetric bow-tie, asymmetric bow-tie, and irregular patterns. Main Outcome Measures: The surface regularity index (SRI), surface asymmetr y index (SAI), PVA index, and topographic pattern of the TMS-1 were compare d between normal and dry eyes and in dry eyes before and after the instilla tion of artificial tears. Results: The SRI and SAI were significantly elevated and the PVA was signif icantly reduced in dry eye patients compared with normal subjects: 0.31 +/- 0.22, 0.30 +/- 0.16, and 20/17.89 +/- 20/3.04, respectively, in normal sub jects and 1.28 +/- 0.73, 1.05 +/- 1.17, and 20/33.45 +/- 20/13.99, respecti vely, in patients with dry eye (P < 0.001 for all indices). The average amo unt of astigmatism was also increased in dry eyes (2.10 +/- 1.96 prism diop ters) compared with normal eyes (1.13 +/- 0.53 prism diopters, P = 0.02). I n dry eyes, the SRI and SAI were positively correlated with corneal fluores cein staining scores (P = 0.005 for SRI and P = 0.016 for SAI). The mean PV A was not significantly different from the mean actual corrected visual acu ity. The dry eyes had a significantly lower percentage of symmetric bow-tie patterns and a greater percentage of irregular patterns on topographic map s than normal eyes. After the instillation of artificial tears, the SRI, SA I, and mean astigmatism all decreased significantly (P < 0.001 for SRI, P < 0.002 for SAI, P = 0.04 for astigmatism) and the PVA improved (P < 0.001) in dry eyes. An irregular topographic pattern was observed in 45.24% of dry eyes, and this decreased to 30.95% after the instillation of artificial te ars (P < 0.005). Conclusions: Patients with aqueous deficiency have an irregular corneal sur face that may contribute to their visual difficulties. The SRI and SAI coul d be used as objective diagnostic indices for dry eye as well as for evalua ting the severity of this disease and the effect of artificial tears. Artif icial tears have the secondary benefit of smoothing the corneal surface in dry eye.