EFFECTS OF REFRACTIVE SURGERY ON BINOCULAR VISION : PRE- AND POST- LASIK VALUES VI INTERNATIONAL CONGRESS OF BEHAVIORAL OPTOMETRY APRIL 2010

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1 EFFECTS OF REFRACTIVE SURGERY ON BINOCULAR VISION : PRE- AND POST- LASIK VALUES JOSÉ DE JESÚS ESPINOSA GALAVIZ, OD, MSc, FCOVD ELIZABETH CASILLAS CASILLAS, OD, MSc JAIME BERNAL ESCALANTE, OD, MSc SERGIO RAMÍREZ GONZALEZ, OD MSc VI INTERNATIONAL CONGRESS OF BEHAVIORAL OPTOMETRY APRIL 2010

2 Introduction More than a million of refractive surgery procedures were done in USA in 2002 Some reports about complications after surgery on binocular vision as a result of the procedure have appeared Regardless of the controversy is about with the procedure with the refractive amblyopia patient, thousands could have the procedure without a comprehensive binocular vision evaluation

3 Binocular Vision Values

4 GENERAL OBJECTIVE Determine the effects of refractive surgery (LASIK procedure) on binocular vision by comparing binocular vision pre surgery values against postsurgery values.

5 SPECIFIC OBJECTIVES Determine binocular vision values in patients who decided to have a refractive surgery, specifically a LASIK procedure before surgery Determine binocular vision values in the same patients after surgical procedure Compare both results and analyze the changes in binocular vision values

6 Methods The research was done in Visual Láser Ocular in Ciudad Victoria, México from May 30 th 2007 until July 31th of Thestudywasdoneinpatientswhodecidedtohave LASIK for either myopia, hyperopia, with or without astigmatism. i All were selected. Sample: 15 patients; 10 women and 5 men. Age range from 24 to 39. All were selected by the ophthalmologist who had only done: refractive studies, corneal topography, ultrasonic pachymetry, fundus evaluation, and corneal testing. ti

7 Hypothesis HYPOTHESIS Refractive surgery DOES change the binocular vision values ALTERNATE HYPOTHESIS: Refractive surgery DOES NOT change binocular vision values

8 Statistical Analysis Statistical analysis was done using a T paired test using SPSS Version 17 Software with the data grouped using the OEP model: a) Habitual phoria for far (#3) b) Habitual phoria for near (#13A) c) Induced d phoria (#8) d) True adduction (first blur) (#9) e) Convergence (break and recovery) (#10 break and #10 rec) f) Abduction (break and recovery (#11 break and #11 rec ) g) Base out to blur out (#16A) h) Base out break (#16B/B) i) Base out to recovery (#16B/R) j) Base in to blur out (#17A) k) Base in break (#17B/B) l) Base in to recovery (#17B/R)

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10 Expectative Prueba Morgan (1944ª, Saladin y Sheedy Jackson y Goss (1991) Expectativas OEP 1944b) (1978) #3 Habitual phoria far.5 exo #13A Habitual phoria near 6 exo #8 Induced phoria far 1 exo 1 exo 1 exo.5 exo #9 BO, blur far a9 #10 BO break/recovery 19/10 28/20 23/6 19/10 #11 BI break/recovery 7/4 8/5 12/4 9/5 #12 Vertical phoria far Orto #13B Induced phoria near 3 exo 0.5 exo 3 exo 6 exo #16ª BO blur near #16B BO break/recovery 21/11 30/23 27/10 21/15 #17ª BI blur near #17B BI break/recovery 21/13 19/13 21/9 22/18 #18 Vertical phoria near Orto #19 Amplitud lente 5.00 D negativo #20 (PRA) a #21 (NRA) a +2.00

11 Final Results Test Media Pre Media Post Difference Habitual phoria far Dist BO Blur (first blur) Dist BO Break Dist BO Recovery Dist BI Break Dist BI Recovery Habitual phoria Near Near BO Blur Near BO Beak Near BO Recovery Near BI Blur Near BI Break Near BI Recovery

12 Graph Gap

13 Statystical Test Media Significance level (p) Habitual phoria far Habitual phoria near BO blur far BO break far BO recovery far BI break far BI recovery far BO blur-out near BO break near BO recovery near BI blur-out near BI break bea near BI recovery near

14 RESULTS On the basis of the above results, the hypothesis is rejected. This means, from an statistic point of view refractive surgery DOES NOT change binocular vision values However

15 Discussion It is well known that the prescription given to a patient can alter phoria values. Example: an overcorrection in myopia with exophoria tends to decrease phoria value, or even in some cases, change it into esophoria. It is also known, the most of refractive surgeons tend to overcorrect in myopia cases in order to anticipate future changes increasing in myopia values.

16 Discussion Nevertheless the results shown binocular vision was satisfactory, if there were changes in phoria and binocular vision values An exophoric myopic patient has never face symptoms of esophoria Although this is still in analysis, 85% of patients in this study, complained about near vision problems as accommodative asthenopia, fatigue, headache, etc.

17 Discusion We believe all of this is due to the overcorrection of myopia. Unfortunately, most of the refractive surgeons have no knowledge about binocular vision evaluation and treatment procedures.

18 Discussion In regard to convergence and divergence resultant values, the was a good degree of variability. There were patients who showed minimal modifications against previous values. Some others had better values and others had worse values. For us, this results mean the re organization that current in an organism as result of a LASIK procedure It is result of the stress imposed on the visual system Thus, a full binocular evaluation should be done bf before refraction surgery.

19 Discussion There are reports about unstable AC/A ratios after refractive surgery that get stabilization around 6 to 9 months after (Prakash et al; 2007) Likewise, visual therapy for patients having symptomatic BV disorders after Lasik procedure (Faktorovich; 2008) Question is: Is the patient prepared to a new p p p environment for near vision?

20 Conclusion Although, only one out of 15 patients shown diplopia for one day (day after surgery), we believe it is important to test binocular vision status before the surgical decision i is made. Only with this data can the OMD evaluate risks about diplopia after the procedure. 85% of patients in this study complained about near vision problems after their surgery. It would be desirable for refractive surgeons to lean on functional optometry in order to evaluate binocular vision.

21 Conclusion Evaluate properly the matter about overcorrection; there are some studies proving that myopia increases slightly yor not at all after ate LASIK teat treatment. e t. It is necessary to have more similar research in order to state a predictable model of binocular vision results after surgery.

22 Gracias Special Thanks to: Dr. Paul Harris for his invaluable help in preparing the document Robert Williams and OEP for all the support Dr. Berenice Velazquez for her help in lecture preparation