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- Gustafsson, Ingemar, et al.
(author)
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An inter-day assessment of the ABC parameters in the evaluation of progressive keratoconus
- 2021
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 11:1
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Journal article (peer-reviewed)abstract
- The progression of keratoconus is commonly determined by comparing the results of corneal tomographic measurements on different occasions. However, investigations on the repeatability of measurements are commonly performed within the same day, thus not taking the inter-day variation into account. The effect of keratoconus disease severity on the measurement error is also seldom considered. In this post hoc investigation, the parameters A, B and C in the Belin ABCD Progression Display were evaluated in relation to disease severity in intra-day and inter-day measurements. Four consecutive measurements were performed on 61 patients with keratoconus on the same day (intra-day). In another cohort, four consecutive measurements were obtained and then repeated 3 days later in 25 patients with keratoconus and 25 healthy controls (inter-day). The results suggest that the diagnosis of disease progression would benefit from inter-day measurements, and the stratification of the parameters A and C according to disease severity. It is also recommended that tomographic systems such as the Pentacam HR be modified to allow the comparison of both single measurements and the mean of replicate measurements of the parameters used in the assessment of progression of keratoconus.
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| 2. |
- Gustafsson, Ingemar, et al.
(author)
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Current clinical practice in corneal crosslinking for treatment of progressive keratoconus in four Nordic countries
- 2023
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In: Acta Ophthalmologica. - : Wiley. - 1755-3768 .- 1755-375X. ; 101:1, s. 109-116
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate clinical practice in the diagnosis and treatment of progressive keratoconus with corneal crosslinking (CXL) in four Nordic countries.METHODS: A questionnaire was sent to all centres at which keratoconus patients are evaluated and CXL is performed in Sweden, Denmark, Norway and Iceland. Nineteen of 20 centres participated.RESULTS: CXL is performed approximately 1300 times per year in these four Nordic countries with a population of around 21.7 million (2019). In most cases, progression is evaluated using the Pentacam HR, and the maximum keratometry reading (Kmax ) is considered the most important parameter. The most frequently used treatment protocol in Scandinavia is the 9 mW/cm2 epi-off protocol, using hydroxylpropyl methylcellulose riboflavin (HPMC-riboflavin). The participants deemed the following areas to be in most need of improvement: adaptation of the CXL protocol to individual patients (5/19), the development of effective epi-on treatment protocols (4/19), optimal performance of CXL in thin corneas (4/19), improvement of the definition of progression (2/19), and diagnosis of the need for re-treatment (2/19).CONCLUSIONS: We concluded that the diagnosis of progressive keratoconus and the diagnostic equipment used are similar. Treatment strategies are also similar but are suitably different to provide an interesting basis for the comparison of treatment outcomes. The high degree of participation in this survey indicates the possibility of future scientific collaboration on CXL focusing on the areas deemed to need improvement. It would also be of interest to evaluate the possibility of creating a Nordic CXL Registry. The high number of CXL treatments performed ensures sufficient statistical power to solve many questions. Such a registry could be an important contribution to evidence-based care and would allow for longitudinal evaluation.
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| 4. |
- Gustafsson, Ingemar, et al.
(author)
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The Interday Repeatability of Parameters for the Assessment of Progressive Disease in Subjects With Less Advanced Keratoconus
- 2021
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In: American Journal of Ophthalmology. - : Elsevier BV. - 0002-9394. ; 225, s. 38-46
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Journal article (peer-reviewed)abstract
- Purpose: 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. Design: Prospective reliability analysis for cases and control eyes. Methods: 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. Results: 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. Conclusions: 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.
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