■ C L I N I C A L S C I E N C E ■ Minimal Refractive Change Induced by Sutureless 23- and 25-Gauge Pars Plana Vitrectomy Andrés Emanuelli, MD; José M. García-Gonzalez, MD; María H. Berrocal, MD; Harry W. Flynn, Jr., MD n BACKGROUND AND OBJECTIVE: This study reports the induced refractive error after 23- and 25-gauge (G) pars plana vitrectomy (PPV). n PATIENTS AND METHODS: In this non-randomized retrospective case series, refractive status was assessed with an autokeratorefractometer 1 week or more before and 6 months after surgery. Patients who had suture placement to close the sclerotomies were excluded from the study. n RESULTS: Among the 50 patients (50 eyes), the mean age was 63 years (range: 42 to 76 years) and 57% were female. Thirty eyes underwent 23-G PPV and 20 INTRODUCTION Scleral sutured incisions using 20-gauge (20-G) pars plana vitrectomy (PPV) may induce a significant change in the corneal curvature and create an associated astigmatism.1 These refractive changes may also eyes underwent 25-G PPV. The mean refractive change was +0.50 diopters (D) sphere, +0.25 D cylinders and the mean axis of cylinder change was 6° for the 23-G group; the mean refractive change was +0.12 D sphere, +0.12 D cylinders and the mean axis of cylinder change was 17° for the 25-G group. n CONCLUSION: Following sutureless small-gauge vitrectomy, there were mild and minimally significant refractive changes in the 23-G and 25-G groups from baseline. [Ophthalmic Surg Lasers Imaging 2012;43:94-96.] be associated with episcleral cautery in areas adjacent to the sclerotomies.2 The induced astigmatism may be avoided in sutureless small-gauge PPV. The purpose of the current study is to report the induced refractive error following sutureless 23-gauge (23-G) and 25-gauge (25-G) PPV. From the Department of Ophthalmology (AE, HWF), Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida; and the Department of Ophthalmology (JMG-G, MHB), Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico. Originally submitted May 13, 2011. Accepted for publication December 7, 2011. Posted online January 19, 2012. Supported in part by grant P30-EY014801 from National Institutes of Health Center, Bethesda, Maryland, and an unrestricted grant to the University of Miami from Research to Prevent Blindness, Inc., New York, New York. Drs. Berrocal and Flynn are consultants for Alcon Laboratories. The remaining authors have no financial or proprietary interest in the materials presented herein. Address correspondence to Andrés Emanuelli, MD, Bascom Palmer Eye Institute, 900 NW 17th Street, Miami, FL 33136. E-mail: [email protected] doi: 10.3928/15428877-20120112-01 94 COPYRIGHT © SLACK INCORPORATED PATIENTS AND METHODS The current study is a non-randomized case series of 50 consecutive patients undergoing 23-G and 25-G PPV. All surgeries were performed by the same surgeon (MB) between January 2009 and January 2010. The indication for surgery was one of the following retinal conditions: epiretinal membrane (n = 14), idiopathic macular hole (n = 14), dense vitreous hemorrhage secondary to diabetic retinopathy (n = 8), rhegmatogenous retinal detachment (n = 4), tractional retinal detachment (n = 7), nonclearing vitreous hemorrhage secondary to branch retinal vein occlusions (n = 2), and floaters (n = 2). The PPV was performed using the Alcon Constellation 25-G and 23-G vitrectomy system (Alcon Laboratories, Fort Worth, TX); the trocars were inserted with a beveled scleral incision after displacement of the conjunctiva at 4 mm from the limbus for phakic patients (n = 26) and 3.5 mm from the limbus for pseudophakic patients (n = 25). The inferior temporal sclerotomy was the site of infusion and both superior quadrant sclerotomies were used for intraocular instrumentation. The study inclusion criteria were the following: self-sealed sclerotomies (no sutured sclerotomies), nonuse of silicone oil tamponade, no history of refractive procedure 6 months before or during the study period, no history of cataract surgery 6 months before or during the study period, no history of corneal surface disease (eg, severe dry eye or corneal opacities), and availability of refractive data 1 week before and 6 months after the PPV procedure. Patients requiring scleral buckling or intraoperative intraocular lens manipulations were excluded from this study. Refractive status was assessed with a TopconKR-8800 autokeratorefractometer (Topcon Corporation, Tokyo, Japan). The refraction was performed 1 week or more before surgery and approximately 6 months after surgery. Changes in the individual groups were analyzed with the Wilcoxon-signed rank test. The difference was considered to be statistically significant at a P value of less than .05. RESULTS The current study consisted of 50 eyes of 50 patients; 30 eyes had 23-G PPV and 20 eyes had 25-G OPHTHALMIC SURGERY, LASERS & IMAGING · VOL. 43, NO. 2, 2012 PPV. No intraoperative complications were noted in any of these eyes. The mean age was 63 years (range: 42 to 76 years) and 57% were female. The spherical refraction prior to vitrectomy for the 23-G group ranged from -4.00 to +4.25 diopters (D) with a mean of +0.18 D (standard deviation of 1.94). The mean astigmatic refraction was -0.85 D (± 0.81) 3 80°. For the 25-G group, the spherical refraction ranged from -5.25 to +2.75 D with a mean of plano (standard deviation of 1.88). The mean astigmatic refraction was - 0.93 D (± 0.80) 3 79°. The mean refractive change from baseline for the 23-G PPV group was +0.50 D sphere (P = .03), +0.25 D cylinders (P = .03), and the mean axis of cylinder change was 6° (P = .05). The maximum hyperopic shift was +0.50 D in spherical equivalent (SE). The maximum myopic shift was -1.00 D in SE. Twenty-two patients (73.3%) became more hyperopic, whereas 6 patients (20.0%) became more myopic. Only 2 patients (6.7%) did not have spherical changes. The maximum axis of cylinder changes was 90°. In 70% of the eyes, there was no change of more than 10° in the axis of cylinder. The mean refractive change from baseline for the 25-G group was +0.12 D sphere (P = .03), +0.12 D cylinders (P = .03), and the mean axis of cylinder change was 17° (P = .015). The maximum hyperopic shift was +0.50 D in SE. The maximum myopic shift was -1.00 D in SE. Eleven patients (55.0%) became more hyperopic, whereas 7 patients (35.0%) became more myopic. There was no change in spherical refraction in 2 patients (10.0%). The maximum axis of cylinder changes was 90°. In 50% of the eyes, there was change of more than 10° in the axis of cylinder. Factors such as age, sex, surgical procedure, or presence of diabetes mellitus did not have any association regarding the amount or direction of the refractive change. DISCUSSION The use of small-gauge sutureless transconjunctival instrumentation for PPV permits several theoretical advantages over traditional sutured 20-G PPV: (1) reduced operative time, (2) less postoperative pain, and (3) earlier postoperative recovery. Wirbelauer et al. showed a substantial increase in refractive corneal astigmatism and noted that corneal topography changes can occur 95 after 20-G PPV, especially in the immediate postoperative period.3 No further changes in the corneal refractive status were observed during follow-up.3 Several studies have demonstrated that no significant corneal topographic changes occur after 25-G PPV.4,5 The healing of a 25-G sclerotomy is generally rapid and the site of the sclerotomy usually is undetectable at 2 weeks postoperatively. On the other hand, the 20-G sclerotomies may take months to heal postoperatively.6 During this period of time, the refractive status may change. In the current study, outcomes at 6 months showed that there were minimal refractive changes in the 23-G and 25-G groups from baseline. The study also showed a slightly greater refractive change in patients who had 23-G PPV. There are various possible explanations for this observed refractive change. PPV may result in an anterior movement of the intraocular lens position, resulting in a myopic shift.7 The effect of PPV on the crystalline lens is also a possible cause for postoperative refractive change. Altered oxygen concentration in the vitreous may damage the crystalline lens and cause subsequent cataract.8 This may explain the significant myopic shift of -1.00 D that was observed in some patients. Due to lack of statistical power, the groups cannot be stratified by the status of the crystalline lens. Limitations of this study include its retrospective nature and the small sample size in both groups. A potential bias is the use of the autokeratorefractometer, 96 which may carry a margin of error of +0.25 D in the SE when compared to the manual refraction.9 In addition, corneal topography was not used in the current study. Small-gauge sutureless PPV induces minimal refractive changes. The favorable refractive outcomes in this study should be considered along with other theoretical advantages of sutureless small-gauge PPV. REFERENCES 1. Jampel HD, Thompson JT, Nunez M, Michels RG. Corneal astigmatic changes after pars plana vitrectomy. Retina. 1987;7:223-226. 2. Avitabile T, Castiglione F, Bonfiglio V, Castiglione F. Transconjunctival sutureless 25-gauge versus 20-gauge standard vitrectomy: correlation between corneal topography and ultrasound biomicroscopy measurements of sclerotomy sites. Cornea. 2010;29:19-25. 3. Wirbelauer C, Hoerauf H, Roider J, Lagua H. Corneal shape changes after pars plana vitrectomy. Graefes Arch Clin Exp Ophthalmol. 1998;236:822-828. 4. Yanyali A, Celik E, Horozoglu F, Nohutcu AF. Corneal topographic changes after transconjunctival (25-gauge) sutureless vitrectomy. Am J Ophthalmol. 2005;140:939-941. 5. Okamoto F, Okamoto C, Sakata N, et al. 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