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Corneal thickness measurements with contact and noncontact specular microscopic and ultrasonic pachymetry

2001; Elsevier BV; Volume: 132; Issue: 4 Linguagem: Inglês

10.1016/s0002-9394(01)01109-6

1879-1891

László Módis, Achim Langenbucher, Berthold Seitz,

Glaucoma and retinal disorders

PURPOSE: To evaluate the central corneal thickness values in normal and postkeratoplasty corneas with the new Topcon SP-2000P noncontact specular microscopic, contact specular microscopic, and the “common standard” ultrasonic pachymetry. METHODS: Central corneal thickness was determined in 119 eyes of 81 patients (73 normal eyes of 44 patients and 46 eyes after penetrating keratoplasty) first with a noncontact specular microscopic (Topcon SP-2000P; Topcon Corporation, Tokyo, Japan), then an ultrasonic (AL-1000; Tomey, Erlangen, Germany), and finally with a contact specular microscopic (EM-1000; Tomey, Erlangen, Germany) pachymetry two times each by the same investigator. RESULTS: Reliability of the central corneal measurements was equally high both in normal and in postkeratoplasty corneas with all of the instruments (Cronbach alpha = 0.99). Noncontact specular microscopic corneal thickness determination correlated significantly both with ultrasonic (r = .86, P < .0001) and contact specular microscopic pachymetry (r = .62, P < .0001). The ultrasonic pachymetry correlated well with the Tomey pachymetry (r = .69, P < .0001). The Topcon normal mean central corneal thickness value (542 ± 46 μm) was 28 ± 4 μm lower (P < .0001) compared with the ultrasonic data (570 ± 42 μm), which was 68 ± 1 μm lower (P < .0001) compared with Tomey thickness (638 ± 43 μm). CONCLUSIONS: Central corneal thickness measurements with noncontact specular microscopic, contact specular microscopic, and ultrasonic pachymetry demonstrate that each of the instruments is reliable but cannot be simply used interchangeably.