Details

Autor(en) / Beteiligte

• Gustafsson, Ingemar
• Bergström, Anders
• Cardiakides, Anna
• Ivarsen, Anders
• Hjortdal, Jesper Østergaard

Titel

The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus

Ist Teil von

• American journal of ophthalmology, 2021-05, Vol.225, p.38-46

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2021

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• To evaluate the interday repeatability in the measurement of parameters used for the detection of progression of keratoconus by prediction limits (PL) for single measurements, and the repeatability coefficient (RC) for the mean of replicate measurements. Prospective reliability analysis for cases and control eyes. Twenty-five eyes in 25 subjects with KC and 25 eyes in 25 healthy controls were included. Four consecutive measurements were made, 3 days apart, with a Pentacam HR tomographic instrument (denoted the Pentacam) and a Nidek ARK 560-A auto-keratometer (denoted the keratometer). Main outcome measures were the intra- and interday RC of parameters used in the detection of progression of keratoconus. The most repeatable parameter obtained with the Pentacam was the curvature power of the central flat meridian (K1, 0.44 D [RC], -0.55 to 0.60 diopter [D] [PL]), followed by the central steep meridian (K2, 0.72 D [RC], -0.90 to 0.94 D [PL]). The interday repeatability of K1 and K2 was similar when using the keratometer (K1, 0.32 D [RC], -0.66 to 0.57 D [PL], K2, 0.93 D [RC], -1.36 to 1.08 D [PL]). The interday repeatability of the curvature power of the steepest point (Kmax, 0.84 D [RC], -0.90 to 1.11 D [PL]) would benefit from being stratified: RC = 0.44 D and PL = -0.49 to 0.67 D for Kmax < 49.0 D, and RC = 1.08 D and PL = -1.19 to 1.42 D for Kmax ≥ 49.0 D. The interday repeatability of measurements, single or replicate, in subjects with keratoconus should be considered when diagnosing progressive disease. K1 exhibited the best intraday repeatability. Kmax benefits from being stratified according to disease severity. •Obtaining measurements by the Pentacam HR over time increases the variation in measurements. The assessment of interday repeatability is thus of importance in understanding at which change in magnitude a true progression can be suspected.•The interday repeatability of Kmax depends on the disease magnitude and must thus be considered.•The use of single, or the mean of several, measurements when estimating disease progression affects the interday repeatability and must be considered.•The use of a common auto-keratometer could be helpful in assessing progression when more advanced equipment is not available.