Quantitative anatomical differences in central corneal thickness values determined with scanning-slit corneal topography and noncontact specular microscopy.
ABSTRACT This study was designed to analyze the differences in central corneal thickness values determined with noncontact specular microscopy and scanning-slit corneal topography. The measurements were performed on the same eye.
We analyzed the central corneal thickness values of 93 patients (n = 93) by means of noncontact specular microscopy (Topcon SP-2000P noncontact specular microscope, Topcon Corp., Tokyo, Japan) and scanning-slit corneal topography (Orbscan Topography System II, Orbscan Inc., Salt Lake City, UT). One experienced physician performed 3 consecutive central corneal thickness measurements with both devices.
The central corneal thickness values obtained by means of Orbscan pachymetry were 17 +/- 2.7 (range, 12-24) microm greater. A significant correlation was observed between scanning-slit corneal topography and noncontact specular microscopy (Pearson correlation coefficient, r = 0.976; P < 0.001).
Researchers should know of the existence of this difference between noncontact specular microscopy and Orbscan pachymetry when interpreting central corneal thickness values.
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ABSTRACT: PURPOSE: The aim of the present study is to assess central corneal edema and visual recovery after cataract surgery performed according to two technologies: conventional ultrasonic and liquefaction (Aqualase®). METHODS:This is a prospective contralateral study in wich 20 patients with comparable preoperative conditions were submitted to cataract surgery were evaluated. Preoperative assessment involved complete ophthalmological examination and the study included patients with bilateral cataracts up to grade 2, according to the Lens Opacity Classification System II. The same cristaline fracture technique was used in all cases, and surgical procedures were performed by the same experienced surgeon, using two technologies: liquefaction or conventional phacoemulsification. Postoperative central corneal edema was measured by corneal optical pachymetry (Orbscan II®) on the 1st, 3rd, 7th and 10th postoperative days. RESULTS:None of the 20 patients submitted to surgery was lost during the postoperative follow-up or excluded from the analysis. On the first postoperative, the visual acuity average was 0.031 logMAR in the Aqualase® group and 0.043 logMAR in the conventional surgery group. No statistical difference was detected in the assessment of visual acuity throughout the postoperative period. Central corneal pachymetry varied from 543.93 + 34.69 preoperatively to 545.08 ± 25.67 on the last day of follow-up in the Aqualase® group, and from 543.13 + 30.62 to 536.08 + 34.89 in the conventional technique group, without statistical significance. CONCLUSION:This study suggests that both techniques are equally effective for surgery on lenses with grade I or II cataract, and that they provide similar results in terms of visual recovery and central corneal edema.Revista brasileira de oftalmologia 01/2009; 68(1). · 0.16 Impact Factor
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ABSTRACT: Background: To determine the prevalence of Orbscan II-derived keratoconus traits in relations of individuals with keratoconus and a control group and to apply these to a pedigree analysis.Methods: In a controlled, prospective, observational case series, four Orbscan II-derived corneal parameters were examined in relations of individuals with keratoconus and a control group of low myopes (<2.5 D). The four parameters and thresholds for abnormality (derived from a literature review) were as follows: average keratometry (≥47.2 D), I-S value (≥1.2 D), posterior float apex (≥42 µm) and thinnest pachymetry (≤463 µm).Results: Forty-four unrelated controls (88 eyes) and eight families with 90 members without known (178 eyes) and 11 members with keratoconus (19 eyes) were analysed. One of 88 (1.14%) control eyes had a single keratoconus trait, and none had more than one trait. Of 178 eyes from relatives of patients with keratoconus, 45 (25.3%) had one or more keratoconus traits. Relatives of patients with keratoconus had an elevated risk of possessing a keratoconus trait (relative risk 14.67, CI 2.07–104.07, P < 0.001) compared with controls. Approximately 53.3% of relatives with a keratoconus trait were evident on either pachymetric or posterior elevation indices alone. Six of eight families suggested dominant inheritance.Conclusions: Keratoconus traits are common in relatives of patients with keratoconus. There prevalence may have been previously underestimated by using placido image-based topography alone where corneal pachymetry and posterior elevation are not assessed. This study suggests an autosomal dominant pattern of inheritance with variable expressivity in some families.Clinical and Experimental Ophthalmology 01/2009; 36(9):824 - 830. · 1.96 Impact Factor