1. MEASUREMENT TO COMPARE THE CORNEAL CENTRAL THICKNESS WITH PENTACAM, VISANTE AND ULTRASONIC PACHYMETRY AT OFTALMOSALUD EYE INSTITUTE Authors: Miranda Mauricio, MD; Gutarra Villavicencio Rosario del Pilar, MD; Izquierdo Jr. Luis, MD; Cañote Flores Renzo, MD; Bernilla F. César, MD. Institution: Instituto de Ojos Oftalmosalud Address: Av. Javier Prado Este 1142 San Isidro. *The authors have no financial interest in the materials being presented

2. To compare the values of measurement of corneal thickness obtained by Pentacam, Visante and Ultrasonic Pachymetry. PURPOSE

3. Prospective, comparative simple study of corneal pachymetry, in a sample of 54 eyes of 54 patients taken care of at OFTALMOSALUD Eye Institute during the period, between November and December of the year 2006. The values of corneal thickness were obtained by 3 devices (Visante®, Pentacam® and ultrasonic Pachymeter Accutome®). MATERIALS AND METHODS

4. Inclusion criteria considered: - Age greater than 18 years old - Patient that accepts to participate voluntarily in the study. - Do not have corneal pathology with the exception of keratocono, any ocular surgery or use of contact lenses. -Do not have family history of ocular disease or systemic disease with ocular manifestations Exclusion criteria considered: - Age lower than 18 years old. - Pregnant women - Previous refracting Surgery - Corneal Pathology except keratocono, ocular surgery or use of contact lenses - Family History of ocular disease or systemic disease with ocular manifestations. MATERIALS AND METHODS

5. All the measurements were made in the afternoon between 4 and 6 p.m., with the purpose of avoiding the normal diurnal variations of the corneal thickness. These studies gave a level of confidence of 95%, during this study 54 subjects showed a probability to have 80% to detect 45µm, of difference in averages. MATERIALS AND METHODS

6. RESULTS The age average of patients was of 28,52 + - DS 7.89. The patient with smaller age was 18 years old and the one of greater age was 58 years old. The 85,2% (46 patients) were of female sex and 14.8% (8 patients) male.

7. RESULTS We obtained a medium correlation between the VISANTE and U.S. of 0,647 (64,7%) and between U.S. and PENTACAM of 0,690 (69%).

8. RESULTS

10. There were variations in the readings of corneal central thickness between the 3 devices. The measures of central corneal thickness in normal eyes with Pentacam revealed an excellent correlation with the results obtained with ultrasonic pachymetry. The measures of corneal thickness with the Visante System turned out to be smaller than with the Pentacam and ultrasonic pachymetry. The results suggest that the Pentacam and the U.S. is equally precise, giving similar readings. CONCLUSIONS

11. REFERENCES 1.Miglior S, Albe E, Guareschi M, Mandelli G, Gomarasca S, Orzalesi N (2004) Intraobserver and interobserver reproducibility in the evaluation of ultrasonic pachymetry measurements of central corneal thickness. Br J Ophthalmol; 88:174-177. 2.Rainer G, Petternel V, Findl O, Schmetterer L, Skorpik C, Luksch A, Drexler W (2002) Comparison of ultrasound pachymetry and partial coherence interferometry in the measurement of central corneal thickness. J Cataract Refract Surg; 28:2142-2145. 3.Gordon A, Boggess EA, Molinari JF (1990) Variability of ultrasonic pachometry. Optom Vis Sci; 67:162-165. 4.Marsich MW, Bullimore MA (2000) The repeatability of corneal thickness measures. Cornea; 19:792-795. 5.Barkana Y, Gerber Y, Elbaz U, Schwartz S, Ken-Dror G, Avni I, Zadok D (2006) Central corneal thickness measurement with the Pentacam Scheimpflug system, optical low-coherence reflectometry pachymeter, and ultrasound pachymetry. J Cataract Refract Surg; 31:1729-1735. 6.Hitzenberger CK, Baumgartner A, Drexler W, Fercher AF (1994) Interferometric measurement of corneal thickness with micrometer precision. Am J Ophthalmol; 118:468-476. 7.Drexler W, Baumgartner A, Findl O, Hitzenberger CK, Sattmann H, Fercher AF (1997) Submicrometer precision biometry of the anterior segment of the human eye. Invest Ophthalmol Vis Sci; 38:1304-1313. 8.Bohnke M, Chavanne P, Gianotti R, Salathe RP (1998) Continuous non-contact corneal pachymetry with a high speed reflectometer. J Refract Surg; 14:140-146. 9.Wong AC, Wong CC, Yuen NS, Hui SP (2002) Correlational study of central corneal thickness measurements on Hong Kong Chinese using optical coherence tomography, Orbscan and ultrasound pachymetry. Eye; 16:715-721. 10. Muscat S, McKay N, Parks S, Kemp E, Keating D (2002) Repeatability and reproducibility of corneal thickness measurements by optical coherence tomography. Invest Ophthalmol Vis Sci; 43:1791-1795. 11.Bechmann M, Thiel MJ, Neubauer AS, Ullrich S, Ludwig K, Kenyon KR, Ulbig MW (2001) Central corneal thickness measurement with a retinal optical coherence tomography device versus standard ultrasonic pachymetry. Cornea; 20:50-54. 12.Modis L, Jr., Langenbucher A, Seitz B (2001) Scanning-slit and specular microscopic pachymetry in comparison with ultrasonic determination of corneal thickness. Cornea; 20:711-714. 13.Chakrabarti HS, Craig JP, Brahma A, Malik TY, McGhee CN (2001) Comparison of corneal thickness measurements using ultrasound and Orbscan slit-scanning topography in normal and post-LASIK eyes. J Cataract Refract Surg; 27:1823-1828. 14.Suzuki S, Oshika T, Oki K, Sakabe I, Iwase A, Amano S, Araie M (2003) Corneal thickness measurements: scanning-slit corneal topography and noncontact specular microscopy versus ultrasonic pachymetry. J Cataract Refract Surg; 29:1313-1318. 15.Rabsilber TM, Khoramnia R, Auffarth GU (2006) Anterior chamber measurements using Pentacam rotating Scheimpflug camera. J Cataract Refract Surg; 32:456 - 459. 16.Price FW, Jr., Koller DL, Price MO (1999) Central corneal pachymetry in patients undergoing laser in situ keratomileusis. Ophthalmology; 106:2216-2220. 17.Doughty MJ, Zaman ML (2000) Human corneal thickness and its impact on intraocular pressure measures: a review and meta-analysis approach. Surv Ophthalmol; 44:367-408. 18.Stodtmeister R (1998) Applanation tonometry and correction according to corneal thickness. Acta Ophthalmol Scand; 76:319-324. 19.Gordon MO, Beiser JA, Brandt JD, Heuer DK, Higginbotham EJ, Johnson CA, Keltner JL, Miller JP, Parrish RK, 2nd, Wilson MR, Kass MA (2002) The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol; 120:714-720; discussion 829-730.