Evaluation of anterior segment structures with Scheimpflug camera in patients undergoing sutureless scleral fixation by modified Yamane technique

Purpose. The relationship between conventional keratometry and total keratometry has not been fully investigated. This study was aimed at conventional keratometry measured with the automated keratometer and total keratometry with the corneal tomographer in ophthalmologically normal subjects. Methods. We enrolled fifty eyes of 50 consecutive subjects (mean age±standard deviation, 34.9±8.0 years) who have no ophthalmologic diseases, other than refractive errors, with no history of ocular surgery. Conventional keratometry was measured with the automated keratometer. The total keratometry, the true net power (TNP), and the total corneal refractive power (TCRP) were measured with the Scheimpflug camera, and the real power (RP) was measured with anterior segment optical coherence tomography (As-OCT). Anterior keratometries (Km and AvgK) were also measured with the Scheimpflug camera and the As-OCT, respectively. Results. Conventional keratometry was 43.64±1.48 D, which was significantly higher than the TCRP (42.94±1.45 D, p=0.042), the TNP (42.13±1.37 D, p<0.001), and the RP (42.62±1.39 D, p=0.001, Dunnett’s test). We found significant correlations between conventional keratometry and each total corneal power (the TCRP (Pearson’s correlation coefficient r=0.986, p<0.001), the TNP (r=0.986, p<0.001), the RP (r=0.987, p<0.001), the Km (r=0.990, p<0.001), and the AvgK (r=0.991, p<0.001)). The intraclass correlations of conventional keratometry with the TCRP, the TNP, the RP, the Km, and the AvgK were 0.986, 0.983, 0.985, 0.990, and 0.990, respectively. We found no significant differences in the keratometric data measured with the automated keratometer, the Scheimpflug camera, and the As-OCT (ANOVA, p=0.729). Conclusions. Conventional keratometry was significantly larger than total keratometry, by approximately 0.70 to 1.52 D, in ophthalmologically normal subjects. By contrast, there were no significant differences in the keratometric data among the three devices. It is suggested that conventional keratometry overestimates the total corneal power in daily practice.

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Diagnostic Value of Modern Methods of Ocular Anterior Segment Visualization in Intumescent Cataract

Ophthalmology in Russia ◽

10.18008/1816-5095-2019-3-350-354 ◽

2019 ◽

Vol 16 (3) ◽

pp. 350-354

Author(s):

O. L. Fabrikantov ◽

S. I. Nikolashin ◽

E. S. Pirogova

Keyword(s):

Anterior Chamber ◽

Anterior Segment ◽

Anterior Chamber Depth ◽

Ultrasound Biomicroscopy ◽

Diagnostic Value ◽

Ligament Length ◽

Anterior Chamber Angle ◽

Lens Thickness ◽

Scheimpflug Camera ◽

Chamber Angle

Purpose: tо evaluate the diagnostic capabilities of optical coherence tomography (OCT), Scheimpflug camera and ultrasound biomicroscopy (UBM) in examining topography of the ocular anterior segment and lens in mature intumescent cataract. Patients and methods. 23 eyes with mature intumescent cataract were examined using OCT (RTVue-100, Optovue, USA), Scheimpflug camera (Pentacam HR, Oculus, Germany) and UBM (UD 8000, Tomey, Japan). We examined the anterior chamber depth, profile and magnitude of the anterior chamber angle, distance “trabecula-iris at 500 microns”, thickness of the liquid lenticular mass layer, lens thickness, Zinn ligament length within four segments, equatorial angle. Results. We managed to measure the anterior chamber depth using UBM and Scheimpflug camera. UBM measurement was 1.96 ± 0.14 mm, Scheimpflug camera — 1.91 ± 0.11 mm. We revealed narrowing of the anterior chamber angle up to 11.54 ± 2.19° in UMB examination, to 11.49 ± 2.17° in OCT measuring and to 11.63 ± 2.21° in examining by Scheimpflug camera. Distance “trabecula-iris 500” was 0.212 ± 0.037 mm in UMB examination, 0.218 ± 0.042 mm — by means of OCT, Scheimpflug camera measurement was unsuccessful. The rest parameters were examined only by UBM. The lens thickness was 5.26 ± 0.13 mm. The anterior layer of liquid lenticular mass was 0.85 ± 0.06 mm. Zinn ligament length in the outer segment was 0.708 ± 0.072 mm, in the internal segment — 0.731 ± 0.089 mm, in the superior segment — 0.704 ± 0.084 mm, in the inferior segment — 0.876 ± 0.089 mm. The equatorial angle in two opposite segments was 32.52 ± 0.92°. Conclusion. Ultrasound biomicroscopy has the biggest value in examining topography of the ocular anterior segment and lens in mature intumescent cataract, since only this method allows achieving the whole complex of data necessary to evaluate the swelling lens parameters. This can serve as a basis for developing the appropriate tactics of surgical intervention.

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