Comparison of Javal-Schiøtz keratometer, Orbscan IIz and Pentacam topographers in evaluating anterior corneal topography.
Clin Exp Optom
; 106(5): 476-483, 2023 07.
Article
en En
| MEDLINE
| ID: mdl-35614035
ABSTRACT
CLINICAL RELEVANCE Inter-instrument variation in anterior corneal shape (ACS) measurement has a consequence for ocular clinical practice. BACKGROUND:
To consider inter-instrument variability in keratometry measurements across the ACS and to explore instrument protocols for determining ACS keratometric analogues (KAs).METHODS:
Mean keratometry/KAs of the right eye were recorded using Javal-Schiøtz keratometer (J-S), Orbscan IIz and Pentacam from 124 subjects (78 females; mean ± SD age 24.71 ± 6.61 years). Mean radii of curvature were obtained for 1-mm wide annular zones extending up to 6 mm (horizontally) and 4 mm (vertically) from the apex for Orbscan and Pentacam. Zonal mean radius of curvature was calculated by averaging keratometry values for all measured points within the zone.RESULTS:
KA (mean ± SD) Horizontal Orbscan (7.80 ± 0.31 mm) and J-S (7.82 ± 0.29 mm) were not significantly different (p = 0.072). Pentacam (7.86 ± 0.29 mm) was significantly flatter than J-S (p < 0.001) and Orbscan (p < 0.001). Vertical Orbscan (7.64 ± 0.31 mm) was significantly steeper than J-S (7.67 ± 0.29 mm, p < 0.005) and Pentacam (7.70 ± 0.29 mm, p < 0.001). Pentacam was significantly flatter than J-S (p < 0.001) and significant flatter than Orbscan across the entire profile (1-4 mm zones horizontal and vertical, p < 0.001). LoAs (CI) J-S/Orbscan ±0.75 mm (0.05-0.18); J-S/Pentacam ±0.72 mm (0.01-0.12); Pentacam/Orbscan ±0.16 mm (0.04-0.08). There was a +0.03 mm positive bias for Orbscan compared to J-S, +0.06 mm positive bias for Orbscan compared to Pentacam and -0.03 mm negative bias for Pentacam compared to J-S.CONCLUSIONS:
Algorithms used by Orbscan and Pentacam to solve the peripheral paraxial ray problem produce significantly different KAs. Instrument-specific KAs cannot be used inter-changeably between instruments. Differences in KA between instruments are not significant for ocular surgery, but may influence rigid contact lens fitting. Pentacam measures flatter than Orbscan and J-S.Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Lentes de Contacto
/
Córnea
Tipo de estudio:
Guideline
Límite:
Adolescent
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Adult
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Female
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Humans
Idioma:
En
Revista:
Clin Exp Optom
Asunto de la revista:
OPTOMETRIA
Año:
2023
Tipo del documento:
Article
País de afiliación:
Reino Unido