EyeWorld India September 2018 Issue

EWAP REFRACTIVE 43 September 2018 the status of the patient’s tear film and anterior corneal surface. “The Placido image from a corneal topographer is valuable in assess- ing the quality of the anterior refracting surface of the eye. The first thing we’re using topography for is to determine whether the patient has ocular surface disease irregularity-related topographical abnormalities. Then we’re screen- ing for pathology, like keratoconus, forme fruste keratoconus, pellucid marginal degeneration, or other things, that might influence our decision on whether the patient is a candidate for cataract surgery in the first place and if so, what type of implant he or she might eventu- ally receive,” he said. If a patient is found to have ocular surface disease, topogra- phy is used to follow the patient’s progress. “That’s one of the key factors in our determining whether a patient has reached an endpoint of sufficient improvement in their ocular surface disease to proceed with refractive cataract surgery,” Dr. Dell said. He uses topography in conjunction with devices like the LENSTAR (Haag-Streit, Koniz, Patient name Tan, Ken K Patient id 0302925345 Date of Birth May 5, 1947 OD Clinic Capture date June 5, 2018 10:10 am Physician - MAPS T N Anterior Axial / Sagittal 0 30 60 90 120 150 180 210 240 270 300 330 As Ts Ps -4 -2 0 2 4 38.5 39.0 39.5 40.0 40.5 41.0 41.5 42.0 42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0 46.5 47.0 47.5 48.0 48.5 49.0 49.5 -4 -2 0 2 4 Standard Scale Standard0.50D Anterior Tangential 0 30 60 90 120 150 180 210 240 270 300 330 As Ts Ps -4 -2 0 2 4 38.5 39.0 39.5 40.0 40.5 41.0 41.5 42.0 42.5 43.0 43.5 44.0 44.5 45.0 45.5 46.0 46.5 47.0 47.5 48.0 48.5 49.0 49.5 -4 -2 0 2 4 Standard Scale Standard0.50D Anterior Elevation 0 30 60 120 150 180 210 240 300 330 As Ts Ps -4 -2 0 2 4  55  50  45  40  35  30  25  20  15  10   5   0  ‒5 ‒10 ‒15 ‒20 ‒25 ‒30 ‒35 ‒40 ‒45 ‒50 ‒55 -4 -2 0 2 4 Standard Scale Standard5μm Anterior Corneal Aberrations 3 (2,-2) Oblique Astigmatism -0.402 4 (2, 0) Defocus 1.558 5 (2, 2) W/A Astig. 1.193 6 (3,-3) Oblique Trefoil -0.238 7 (3,-1) Vertical coma 0.292 8 (3, 1) Horizontal coma -0.215 9 (3, 3) Horizontal Trefoil -0.085 10 (4,-4) Oblique Tetrafoil -0.020 11 (4,-2) Obl. 2 nd Ast. -0.062 12 (4, 0) Spherical Aberration 0.371 13 (4, 2) W/A 2 nd Astig. 0.021 14 (4, 4) Horizontal Tetrafoil 0.025 K-READINGS (n=1.3375) Keratometric SimK Average K 44.93D (7.51mm)  Steep K 45.53D (7.41mm)@174° Flat K 44.34D (7.61mm)@ 84° Astigm. 1.19D Total Cornea Average K 43.79D  Steep K 44.56D@178° Flat K 43.02D@ 88° Astigmatism 1.53D Equivalent K Average K 44.89D  Steep K 45.66D@178° Flat K 44.12D@ 88° Astigmatim 1.53D (n=1.336) Posterior SimK Average K -6.54D (6.12mm)  Steep K -6.69D (5.98mm)@110° Flat K -6.39D (6.26mm)@ 20° Astigmatism -0.29D QUALITYFACTORS Centration 93% Focus 100% Corneal Coverage 100% Stability 100% Posterior 100% NOTES SURFACE INDICES Q (Asphericity) 0.015 W2W/HVID 11.0mm Pupil size 1.80mm Pupil center 0.30mm@ 14° HOA 0.591μm SRI 0.239 SAI 1.055 S/N ca1523 VERSION 2.5.0 DIAGNOSTICREPORT A standard Cassini display that shows anterior, posterior, and total astigmatism The seven LEDs of the Cassini with the bright re ections off the anterior corneal surface and the faint but measurable images re ecting off the posterior corneal surface. Source: Douglas Koch, MD, and César Villar, MD Switzerland) and the IOLMaster (Carl Zeiss Meditec, Jena, Germany) to verify and confirm that he has achieved good readings on the patient’s overall corneal power and corneal astigmatism. Dr. Dell screens for posterior corneal astigmatism using devices like the Pentacam (Oculus, Wet- zlar, Germany) in patients who are having laser refractive surgery or corneal refractive surgery. “We don’t routinely image the posterior corneal curvature in our cataract patients because we haven’t found it to be consistently helpful, so we use nomogram-based adjustments of our toric power calculations that have been described well, either in some of the modern IOL astigmatic toric calculators or nomogram ad- justments like that proposed by Dr. Koch and Li Wang, MD ,” he said. Lens calculations Dr. Koch is using corneal topog- raphy, in combination with other tools, to determine lens calcula- tions. “We look at the anterior cor- neal astigmatism, and we look at the total corneal astigmatism with the Galilei [Ziemer, Port, Switzer- land]. I am also using the Cassini continued on page 44