Effect of phacoemulsification on corneal thickness

Download Effect of phacoemulsification on corneal thickness

Post on 31-Oct-2016

214 views

Category:

Documents

1 download

TRANSCRIPT

  • BRIEF REPORTS

    Effect of Phacoemulsification onCorneal ThicknessJose Manuel Vargas, MD,James P. McCulley, MD,R. Wayne Bowman, MD, Eric W. Johnston, MD,Binoy R. Jani, MD, and Joanne Shen, MD

    PURPOSE: To determine the immediate effect on cornealthickness of cataract extraction using phacoemulsifica-tion.DESIGN: Prospective consecutive nonrandomized humansundergoing standard small-incision phacoemulsificationand intraocular lens insertion.METHODS: Corneal thickness was measured immediatelypreoperative and postoperatively in 58 consecutive pa-tients undergoing phacoemulsification in the absence ofother ocular abnormalities. Corneal thickness was deter-mined centrally and in the midperiphery of four quad-rants. The last 17 eyes were also evaluated for the effectof pressure from a Honan balloon on corneal thickness.SETTING: Faculty practice in medical school and univer-sity hospital.RESULTS: The cornea thinned in all five of the measuredlocations, with statistical significance being reached onlyin the four midperipheral quadrants. Pressure from theHonan balloon resulted in a negligible increase in cornealthickness preoperatively.CONCLUSIONS: Corneas were found to have thinned sta-tistically significantly immediately after phacoemulsifica-tion; however, the degree of thinning has doubtfulclinical significance and does not represent a significantdehydration of the cornea during the surgical procedure.(Am J Ophthalmol 2003;136:171172. 2003 byElsevier Inc. All rights reserved.)

    THE IMMEDIATE EFFECT OF PHACOEMULSIFICATION ONcorneal thickness is not known or necessarily intu-itively obvious. Compromise of corneal endothelial func-tion during surgery could lead to a transient increase incorneal thickness as measured by pachymetry, althoughdata pertaining to this are contradictory. Previous reportsof increased corneal thickness after phacoemulsificationdescribe variable increases in thickness months after sur-gery and were associated with endothelial cell loss13 withmost corneas having returned to normal thickness by 1month.4 No previous reports describe the thickness of thecornea immediately after surgery. However, there havebeen recent suggestions that the cornea might thin signif-icantly during phacoemulsification and produce a settingin which the cornea would be primed to imbibe largeamounts of topically applied medications. Conversely, thesurgery could compromise endothelial function and resultin immediate corneal swelling. This study was done todetermine what immediate corneal thickness changes oc-cur with phacoemulsification.

    Prospectively, 58 consecutive patients without concur-rent ocular pathology scheduled to undergo small incisioncataract surgery at our institution were included in thisstudy. No patient risks were determined and the study wasdone under the principles of Best Medical Judgment.Corneal pachymetry measurements were done with theCorneo-Gage Plus pachymeter (Sonogage, Inc., Cleve-land, Ohio, USA) immediately before and followingphacoemulsification. The last 17 also were measured beforeand 20 minutes after placement of a Honan balloon set at25 mm Hg. Readings were taken centrally and in the fourmid-peripheral quadrants. Ten readings were taken at eachsite, yielding a minimum of six readings with 10 mvariation. All eyes had 3.0-mm temporal clear cornealincisions. A viscoelastic material containing 4% sodiumchondroitin sulfate and 3% sodium hyaluronate (Viscoat;Alcon Surgical, Fort Worth, Texas, USA) with an osmo-larity of 325 mOsM 40 mOsM, pH 7.2 0.02 wasinjected before continuous curvilinear capsulorhexis andtotally removed at the end of the procedure. Balanced saltsolution (BSS) with epinephrine added was used as anirrigating solution. Hydrodissection and delineation wereaccomplished with BSS. The nucleus was removed byphacoemulsification in the bag with the Legacy 20,000(Alcon Surgical) with an average phacoemulsificationtime of 2.23 1.16 minutes. Cortex removal was com-pleted with the I and A mode of the same machine.

    Accepted for publication Jan 13, 2003.InternetAdvance publication at ajo.com Feb 21, 2002.From the Department of Ophthalmology, The University of Texas,

    Southwestern Medical Center at Dallas, Dallas, Texas.Supported in part by an unrestricted research grant from Research to

    Prevent Blindness, Inc., New York, New York.Inquiries to James P. McCulley, MD, Department of Ophthal-

    mology, UT Southwestern Medical Center, 5323 Harry Hines Blvd.,Dallas, TX 75390-9057; fax: (214) 648-9061; e-mail: james.mcculley@utsouthwestern.edu

    2003 BY ELSEVIER INC. ALL RIGHTS RESERVED.0002-9394/03/$30.00 171

  • Acrysoft SA60AT IOLs (Alcon Laboratories, Inc., FortWorth, Texas, USA) were placed in the bag in all eyes.Corneas were not allowed to dry and were kept lubricatedthroughout the procedure with BSS drops. Average surgi-cal time from speculum insertion to removal was 18minutes 5 minutes.

    Statistical significance was determined using the Stu-dent t test. The immediate and postphacoemulsificationcorneal thickness from the center and midperiphery of fourquadrants are illustrated in Table 1. In the subset ofpatients examined for the effects of the Honan balloon oncorneal thickness, the mean corneal thickness increased by3.0 m (P .59). Even though the thinning is statisticallysignificant, it is minimal and of doubtful clinical signifi-cance.

    Control of corneal hydration involves the following fivefactors: stromal swelling pressure, barrier function of theepithelium and endothelium, endothelial and epithelialpumps, evaporation, and intraocular pressure. Principledehydrating forces are: the active endothelial pump sys-tem, positive intraocular pressure, evaporation, and a smallnet effect of the epithelial pumps.

    Intuitively, we could assume a compromise of endothe-lial cell function during surgery, which could cause corneasto be swollen postoperatively. Surprisingly, the oppositewas found. Possible explanations for this are: increasedevaporation or elevated intraocular pressure (IOP) duringphacoemulsification.

    Our data demonstrate minimal thickening of the corneaafter application of the Honan balloon. Furthermore, it isremarkable that the corneal thickness with phacoemulsi-fication changes little. However, statistical significance wasfound with a consistent decrease in corneal thicknesspostoperatively in the corneal midperiphery. Clinical sig-nificance of this small change is doubtful and does notsuggest a thirsty stromal sponge poised to imbibe topi-cally applied medication.

    REFERENCES

    1. Binder PS, Sternberg H, Wickham MG, Worthen DM.Corneal endothelial damage associated with phacoemulsifica-tion. Am J Ophthalmol 1976;82:4854.

    2. Sugar J, Mitchelson J, Kraff M. The effect of phacoemulsifi-

    cation on corneal endothelial cell density. Arch Ophthalm-mol 1978;96:446448.

    3. Abbott RL, Foster RK. Clinical specular microscopy andintraocular surgery. Arch Ophthalmol 1979;97:14761479.

    4. Rao GN, Shaw EL, Arthur EJ, et al. Endothelial cell morphol-ogy and corneal deturgescence. Ann Ophthalmol 1979;11:885899.

    Retention of Dye After IndocyanineGreen-assisted Internal LimitingMembrane PeelingMasayuki Ashikari, MD, Hironori Ozeki, MD,Kazuyuki Tomida, MD, Eiji Sakurai, MD,Kazushi Tamai, MD, and Yuichiro Ogura, MD

    PURPOSE: To describe the long-term retention of indocya-nine green (ICG) in the fundus after ICG-assistedinternal limiting membrane peeling.DESIGN: Case report.METHODS: Two patients underwent vitrectomy includingICG-assisted internal limiting membrane peeling. Thefundus was examined with a 780-nm infrared illumina-tion of a scanning laser ophthalmoscope after surgery.RESULTS: No ICG staining of the fundus was visibleophthalmoscopically. Examination with a scanning laserophthalmoscope, however, detected fluorescence fromresidual ICG until 6 months after surgery in case 1 and9 months in case 2. No complication related to theresidual ICG was observed.CONCLUSIONS: The results suggested that ICG remains inthe fundus for a long period after surgery. Clearance ofthe dye from the diabetic retina may be prolonged. (AmJ Ophthalmol 2003;136:172174. 2003 by ElsevierInc. All rights reserved.)

    Accepted for publication Jan 3, 2003.InternetAdvance publication at ajo.com Feb 26, 2003.From the Department of Ophthalmology, Nagoya City University

    Medical School, Nagoya Japan.Inquires to Masayuki Ashikari, MD, Department of Ophthalmology,

    Nagoya City University Medical School, 1-Kawasumi, Mizuho-cho,Mizuho-ku, Nagoya 467-8601, Japan; fax: (81) 52-841-9490; e-mail:ma-kou@t-gh.bias.ne.jp

    TABLE 1. Corneal Thickness Before and Immediately After Phacoemulsification

    Site Pre-Phaco Pachymetry Post-Phaco Pachymetry P Value

    Central 556 36 m 548 41 m .33

    Superotemporal 655 52 m 609 46 m .00004

    Inferotemporal 632 55 m 604 45 m .014

    Superonasal 662 47 m 625 47 m .0004

    Inferonasal 651 60 m 616 51 m .006

    Phaco phacoemulsification.

    AMERICAN JOURNAL OF OPHTHALMOLOGY172 JULY 2003

    Effect of Phacoemulsification on Corneal ThicknessREFERENCES

Recommended

View more >