Eyeworld

EW FEATURE 67 February 2011 September 2011 Challenging cataract cases International point of view Rio de Janeiro, Brazil T he presence of pterygium among cataract surgery patients or refractive candidates is a common situation that should be carefully considered. Pterygium may disturb the patient because of the chronic red eye appearance, be- cause of ocular surface symptoms, or due to its refractive impact. Pterygium can be quies- cent with little vascularity on asymptomatic patients. However, it can be active with in- flammatory signs exhibiting a rapid growth. Typically, induced astigmatism is with-the- rule because corneal curvature is flattened along the long axis of the pterygium body. It is important to stage the extension of the pterygium on the cornea and to evaluate its effect on corneal curvature and ocular aberrations. 1 I find it useful to classify pterygium based on its extension onto the cornea in relation to the pupillary margin. Pinguecula would be the appropriate term when it does not overpass the limbus. As suggested by Maheshwari, 2 grade I is considered if pterygium extends up to a point midway between limbus and pupillary margin; in grade II, the head of the pterygium does not reach the nasal pupillary margin (or temporal margin in case of tem- poral pterygium) and grade III when it presents crossing the pupillary margin. Placido's disk-based topography has been widely used for evalu- ating corneal irregularities induced by pterygium. 1 Scheimpflug-based corneal tomography (Figure 1) may provide additional information about the pterygium since it is not sensitive to the poor reflection related to the ir- regular tear film. The decision related to pterygium surgery depends on a combination of its grade, topographic alterations, and clinical picture. All cases will likely benefit from ocular surface optimization as in dry eye patients, 3 including artificial tears with no or low toxic preservatives, omega-3 essential fatty acid supplementation, 4 and in some circumstances, anti-inflammatory treatment. Vasoconstrictors should be used with extreme parsimony. De- pending on the topographic changes, the excision of pterygium may result in significant steepening of the cornea and reduction of astigmatism. Some cases may reduce over 5 D of cylinder (Figure 2). I usually recommend pterygium excision prior to cataract surgery since it will significantly impact intraocular lens (IOL) power calculation prior to laser vision correction. However, some cataract cases may do well with combined surgery depend- ing on topographic and tomographic changes. Different techniques have been proposed for minimizing pterygium re- currence, from bare sclera surgical excision to different conjunctival graft techniques. 8 Mitomycin C is effective to reduce pterygium recurrence. 5 However, in cases of free conjunctival grafts, it is important to avoid intra- operative use of mitomycin C. My preference is to inject mitomycin C into the head at the slit lamp under topical anesthesia 1 month before surgery as proposed by Donnenfeld. 6 If the patient is younger than 30, I would per- form a free superotemporal conjunctival graft; otherwise a pedunculated su- peronasal graft is preferred. I prefer 10-0 mononylon for single stitches, or fibrin glue may be used. 7 Editors' note: Dr. Ambrósio Jr. is the director of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil, and associate pro- fessor, Federal University of São Paulo, Brazil. Contact information Ambrósio: renatoambrosiojr@terra.com.br Figure 1 Source: Renato Ambrósio Jr., M.D., Ph.D. Figure 2 Source: Renato Ambrósio Jr., M.D., Ph.D. Renato Ambrósio Jr., M.D., Ph.D. References 1. Gumus K, Erkilic K, Topaktas D, Colin J. Effect of pterygia on refractive indices, corneal topography, and ocular aberrations. Cornea. 2011 Jan;30(1):24-9. 2. Maheshwari S. Pterygium-induced corneal refractive changes. Indian J Ophthalmol. 2007 Sep- Oct;55(5):383-6. 3. Ambrósio R Jr., Tervo T, Wilson SE. LASIK-associated dry eye and neurotrophic epitheliopathy: patho- physiology and strategies for prevention and treatment. J Refract Surg. 2008 Apr;24(4):396-407. 4. Ambrósio RJ, Stelzner SK, Boerner CF, Honan PR, McIntyre DJ. Nutrition and dry eye: the role of lipids. Rev Refract Surg. 2002:29-32. 5. Ang LP, Chua JL, Tan DT. Current concepts and techniques in pterygium treatment. Curr Opin Oph- thalmol. 2007 Jul;18(4):308-13. 6. Donnenfeld ED, Perry HD, Fromer S, Doshi S, Solomon R, Biser S. Subconjunctival mitomycin C as adjunctive therapy before pterygium excision. Ophthalmology. 2003 May;110(5):1012-6. 7. Rubin MR, Dantas PE, Nishiwaki-Dantas MC, Felberg S. Efficacy of fibrin tissue adhesive in the at- tachment of autogenous conjunctival graft on primary pterygium surgery. Arq Bras Oftalmol. 2011 Apr;74(2):123-6.

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