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Edward Trudo; Tomographic Analysis and Outcomes of Refractive Surgery Patients with Posterior Embryotoxon. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1535.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the atypical tomographic features of patients with posterior embryotoxon of the cornea and review impact on refractive surgery outcomes.
Retrospective analysis of 1015 consecutive refractive surgery patient records wherein all atypical examination and tomographic features were prospectively monitored as part of a quality improvement process. Eighteen (18) patients were identified as having posterior embryotoxon in one or both eyes. Nine (9) of these patients met the inclusion criteria of available preoperative Scheimpflug images and seven (7) patients met the requirement of at least 3 months of postoperative data.
The average patient age was 22.1 years. The mean preoperative manifest refraction spherical equivalent was -4.01, the mean cornea pachymetry at the thinnest point was 556.72 microns, the mean back surface elevation (BSE) of clinically affected eyes was 19.85. The Corneal Thickness Spatial Profile (CTSP) was steeper than normal in 16/18 (89%) eyes. The I-S ratio mean was 0.76. None of the patients showed significant anterior surface elevation (mean = 3.72) or significant corneal thinning compared to the pupil position pachymetry (mean = 1.722 microns) indicative of ectasia risk. The postoperative uncorrected visual acuity mean was 20/16.4 (range 20/10-20/20) with 3-12 months of data.
Patients who present for refractive surgery evaluation and show greater than normal BSE and steeper CTSP should be evaluated for posterior embryotoxon to differentiate these patients from form fruste keratoconus. The anatomic changes of posterior embryotoxon may show a greater BSE and steeper CTSP on best fit sphere. Careful analysis of the I-S ratio, thinnest pachymetry change, and front surface elevation is helpful is differentiating these patients from those at risk for ectasia. Short term refractive surgery results indicate no unfavorable outcomes, irregular healing, or unexpected astigmatism.
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