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Mauro Campos, Ester Sakae and Rossen Hazarbassanov Federal University of São Paulo Brazil

Effects of Epithelium and Corneal Density in Vision and Ocular Biomechanical Properties : Imaging Analysis. Mauro Campos, Ester Sakae and Rossen Hazarbassanov Federal University of São Paulo Brazil.

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Mauro Campos, Ester Sakae and Rossen Hazarbassanov Federal University of São Paulo Brazil

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  1. EffectsofEpitheliumandCornealDensity in Visionand Ocular BiomechanicalProperties: ImagingAnalysis Mauro Campos, Ester Sakae and Rossen Hazarbassanov Federal University of São Paulo Brazil

  2. None of the authors have any financial interest in the methods and products included here.

  3. Background • Biomechanic properties of the cornea have been studied with increasing interest in the present time (1) • Corneal hysteresis (CH) is a function of the corneal viscous damping properties. It reflects the capacity of the corneal tissue to absorb and release energy (2) • Corneal pathologies such as Fuchs, keratoconus and Lasik may decrease CH values (3) • Scheimpflug images of the eye allow quantification of structural density (4)

  4. Purpose and Study Design • To correlate biomechanical properties, corneal density and vision in a model of corneal opacity • Prospective consecutive interventional case series

  5. Methods • Patients with recalcitrant corneal opacities after epidemic keratoconjunctivitis that failed to respond to medical therapy • All eyes underwent phototherapeutic keratectomy with 0.002% mitomycin C to improve corneal transparency and surface irregularities • Pre and postoperative evaluation included visual acuity measurements, slit lamp exam and Goldmann tonometry, corneal biomechanical indexes (CH, corneal resistance factor – CRF, corneal compensated ocular pressure –IOPCC and Goldmann calculated ocular pressure – IOPG as produced by ORA (Reichert Instruments) and Scheimpflug quantification of corneal density and central corneal thickness - CCT (Pentacan, Oculus)

  6. Methods Preoperativeevaluationof a representativepatientanddetailsofdensitometry Data fromrotationalscheimpflugcamerawasevaluatedat 0, 45, 90 and 135 degrees Linear densitywasgivenplacingthe cursor over a singlepoint Areadensitywasperformedusingstandardizedrectangularareawiththesizedistributedequallyonthe visual axis

  7. Methods Trans epithelium PTK set to a meanof 68 micronsbasedonopacitiesdepthfollowedby 0.002% mitomycin application (detailspreviouslypublished, reference 5) Preoperative Postoperative

  8. StatisticalMethods • Box plot representation of BSCVA, corneal biomechanical indexes (CH, CRF, IOPG and IOPCC), corneal density and corneal thickness (CCT) • Pearson linear correlation between BSCVA and density, CH and density and CH and CCT. • Student t-test for the comparisions of pre and postoperative values (BSCVA, CH, CRF, IOPG and IOPCC and CCT) • SPSS (SPSS Inc, version 15) software for data analysis • LogMAR units were used for vision analysis

  9. Results • Thirty-one eyes from 23 patients included • Mean follow-up was 10.2±3.2 months • 100% followed for 3 months • 87% followed for 6 months • 74% followed for 12 months

  10. 20/20 - 20/40 UCVA 20/50 - 20/80 100% > 20/80 81,5% 80% 60% 46,7% Percentage of patientsy 40,0% 40% 18,5% 20% 13,3% 0,0% 0% PREOP PO 6M Time BSCVA PO 3M PO 6M 100% 79,2% 80% 65,5% 60% Percentage of patients 40% 20,7% 16,7% 20% 13,8% 4,2% 0,0% 0,0% 0,0% 0,0% 0% Lost 2 or > Lost 1 line No change Gain 1 line Gain 2 or > lines lines Time Results, visual acuity For illustrationonly, sixmonths data, contrastsensitivityincluded

  11. Table 1: Summary of all variables before and after PTK.. MeanvalueMediumMinimumvalueMaximumvalue density Biomechanicalvariables

  12. Results Linear andareadensitydecreasedsignificantlyaftertreatment Bettercorrelationbetween BSCVA andareadensityafter PTK comparedwith linear density

  13. Results Correlationsbetweenareaand linear densityand CH wereweakandnegative, withoutsignificance Preoperatively, bettercorrelationbetween CCT and CRF than CCT and CH Postoperatively, bettercorrelationbetween CCT and CH comparedwith CCT and CRF

  14. Conclusionsandselectedreferences • According with the data presented here, as corneal density decreases, BSCVA increases • Increased corneal density decreases correlation among biomechanical indexes and other variables such as CCT • 1. Kotecha A et al. IOVS 2006;47(12):5337-47 • 2. Liu J et al,. JCRS 2005;31(1):146-55 • 3. Luce DA. JCRS 2005:31(1):156-62 • 4. Dobbs RE et al. Ophthalmology 1987;94(7):881-90 • 5. Sakae, E et al. AJO 2011;151(1):35-43

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