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Myopia: More Than a Refractive Error − Lasik and Retinal Dystrophies

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MYOPIA: MORE THAN A REFRACTIVE ERROR − LASIK AND RETINAL DYSTROPHIES WALRAEDT S.1*, LEROY B.P.1,2*, KESTELYN P.H.1, DE LAEY J.J.1 SUMMARY SAMENVATTING Three patients who had undergone laser in situ Drie patiënten die een correctie van myopie hadden keratomileusis (LASIK) correction for myopia were ondergaan met laser in situ keratomileusis (LASIK) first seen because of suboptimal visual acuity (VA) werden onderzocht omwille van postoperatieve sub- and night blindness and/or photophobia. After a com- optimale visus en nachtblindheid en/of fotofobie. Na prehensive examination including psychophysical uitgebreid onderzoek met inbegrip van psychofysi- and electrophysiological tests, two of the three pa- sche en electrofysiologische testen werd een dia- tients were shown to suffer from a progressive cone- gnose van progressieve kegeltjes-staafjesdystrofie ge- rod dystrophy. The third patient had retinitis pig- steld bij twee patiënten. De derde patiënt leed aan mentosa. These cases illustrate the need for in depth retinitis pigmentosa. Deze gevallen illustreren de preoperative evaluation in myopic patients about to noodzaak van een doorgedreven preoperatief onder- undergo LASIK when signs or problems of night blind- zoek bij myope patiënten die LASIK zullen onder- ness and/or photophobia are present. gaan met klachten van nachtblindheid en fotofobie. KEY WORDS RÉSUMÉ Retinal dystrophy, cone-rod dystrophy, Trois patients sont présentés ayant été examinés pour retinitis pigmentosa, photophobia, night une acuité visuelle sous-optimale et une héméralo- blindness, laser in situ keratomileusis, pie et/ou photophobie, après correction d’une myo- preoperative evaluation pie suivant la technique du laser in situ keratomi- leusis (LASIK). Sur base d’une évaluation élaborée, MOTS-CLÉS y inclus des tests psychophysiques et éléctrophysio- logiques, un diagnostic de dystrophie des cônes et Dystrophie rétinienne, dystrophie de type bâtonnets a été établi chez deux patients. Le troisième cônes-bâtonnets, rétinite pigmentaire, patient souffrait d’une rétinite pigmentaire. Ces cas photophobie, héméralopie, laser in situ soulignent la nécessité d’une évaluation préopéra- keratomileusis, évaluation préopératoire toire approfondie de patients myopes qui vont subir du LASIK quand ils présentent des signes ou pro- blèmes d’héméralopie et/ou photophobie. zzzzzz 1 Department of Ophthalmology & 2 Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium * These authors contributed equally to this work received: 28.09.05 accepted: 17.10.05 Bull. Soc. belge Ophtalmol., 298, 31-38, 2005. 31 INTRODUCTION We report three patients who underwent LASIK correction for myopia and were subsequently Laser in situ keratomileusis (LASIK) is a very examined by us because of suboptimal visual popular and effective surgical technique to cor- acuity and night blindness and/or photopho- rect mild or moderate and even high myo- bia. All three patients underwent a comprehen- pia (20). As for any surgical procedure, sever- sive ophthalmological, psychophysical and elec- al postoperative complications have been de- trophysiological examination. scribed. Although these complications are most- ly related to the cornea (flap, interface, strom- al bed) retinal and optic nerve problems have CASE REPORTS also been described after LASIK (1,27,29,32). Complications related to the cornea include dry Case 1: eye syndrome, flap displacement, flap melt- ing, diffuse lamellar keratitis, infection, epithe- A healthy 48-year-old man was examined in lial ingrowth, keratectasia, corneascleral per- our department because of decreased visual forations and irregular astigmatism acuity, photophobia, monocular diplopia and (4,27,29,30). Reported complications in fun- complaints of seeing halos around the lights, do are peripheral retinal tears, retinal detach- after an uneventful bilateral LASIK. ments, macular haemorrhages, central retinal The preoperative best-corrected visual acuity vein occlusion, macular holes, choroidal neovas- (BCVA) was 7/10 in the right eye and 8/10 in cular membranes and ischemic optic neurop- the left eye. The refractive error prior to sur- athy (1,2,12,14,18,22,23,25,27-29,32). gery was −8,0D(−1,50D)170° in the right eye and −5,25D(−1,75)165° in the left eye. Pre- Retinitis pigmentosa (RP) is the term for a group operative slit lamp examination and intraocu- of inherited disorders of the retina character- lar pressure were unremarkable in both eyes. ized by a progressive loss of photoreceptors (3). Fundoscopy had apparently revealed pigment All types of RP lead to typical fundoscopic chang- alterations in both macular areae. es including outer retinal atrophy and intraret- He received a second LASIK treatment in the inal pigmentary changes more pronounced in right eye because of deterioration of central vi- the retinal periphery, secondary attenuation of sion thought to be related to a myopic refrac- the retinal vasculature and progressive atro- tive regression of 1,25D 1 week after initial phy of the nerve fiber layer leading to a waxy treatment. aspect of the optic nerve head (3). Symptoms We saw the patient for the first time 17 months include early night blindness, progressive loss post LASIK treatment. He was referred to our of the peripheral visual fields and subsequent department because of poor central vision. Day- loss of central vision (3). The age of onset of light vision was satisfactory. RP as well as severity of disease is highly vari- The BCVA in the right eye was 3/10 with able. The condition can be inherited as an au- −0,50D(−0,50D)90° and 6/10 without correc- tosomal dominant, an autosomal recessive or tion in the left eye. an X-linked trait (3). Knowledge of the molec- Slit lamp examination revealed superficial stro- ular background of RP is expanding rapidly (7). mal opacities, more pronounced in the right than the left eye. A slightly superiorly decen- Cone-rod dystrophy is also a clinically and ge- tered ablation in the right eye and a regular ab- netically heterogeneous progressive disorder lation in the left eye were seen on corneal to- first affecting the cones and subsequently also pography. Fundoscopy and conventional fluo- the rods, in which patients characteristically rescein angiography showed macular pigment complain of reduced visual acuity, photopho- alterations apart from myopic choroidosis (Fig- bia and impairment of colour vision (3,7). The ure 1). There was no sign of subretinal choroi- age of onset is variable, but most patients present dal neovascularisation. Goldmann visual field in the first two decades of life. Visual loss slow- (VA) analysis showed mild to moderate loss of ly progresses to a level of counting fingers in central sensitivity and moderate concentric nar- the later stages of the disease. rowing in both eyes. Colour vision examination 32 Figure 1. Composite of fundus pictures, fluorescein angiographies (FA) and Goldmann visual field analysis (GVF); Panels a & b: RE & LE respectively of patient 1, illustrating retinal pigment epithelial alterations in central macular region; Panelsc&d: window defects give clearer view of changes in patient 1 on FA Panelse&f: RE & LE respectively of patient 2, showing only myopic changes with tilted disc and temporal peripapillar chorioretinal atrophic crescent Panelsg&h: macular & nasal midperiphery respectively of patient 3 with evidence of myopic fundus, with bull’s eye aspect in the macular area, small tilted optic disc with myopic conus, albinoid aspect of retina and attenuation of retinal vessels; a few areas of spicular intraretinal hyperpigmentation in nasal periphery Panelsi&j: early phase FA of RE better illustrates bull’s eye maculopathy and atrophic aspect of both posterior pole and periphery Panelsk&lmoderate constriction of visual fields and reduced sensitivity on Goldmann VF analysis, with large peri- central scotoma in RE and incomplete annular scotoma with temporal island in LE respectively revealed a red-green defect in both eyes. ISCEV- seeing halos around lights. The preoperative standard electroretinography showed slightly BCVA was 10/10 in both eyes. The refractive subnormal scotopic responses. Oscillatory po- error before surgery was −2,50D(−2,50D)18° tentials were only residual, whilst combined in the right eye and −5,0D in the left eye. Pre- maximal rod-cone responses showed ampli- operative slit lamp examination and intraocu- tudes of about 3/5 of normal values. Both the lar pressure were unremarkable in both eyes. photopic transient responses as well as the 30Hz Fundoscopy had shown myopic choroidosis. flicker responses were reduced to 1/3 of nor- He underwent his first LASIK treatment in the mal values (Figure 2). Goldmann-Weekers dark left eye. After this first treatment he complained adaptometry thresholds were elevated approxi- of poor night vision. Because of this the LASIK mately 1,25 log units. in the right eye was postponed, but four years These results are compatible with a diagnosis after his first treatment he underwent a first of cone-rod dystrophy. LASIK treatment in the right eye and a redo in the left eye. Case 2: The patient was referred for the first time to our A healthy 48-year-old man was referred be- department 4 1/2 years later after his first LASIK cause of complaints of poor night vision and treatment because of poor central vision, com- 33 Figure 2. ISCEV standard electroretinographies of patients; oscillatory potentials not shown; note differences in scaling; Panel a: ERG of patient 1: slightly subnormal scotopic
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