PURPOSE: To evaluate the efficacy and safety of mitomycin C (MMC) 0.02% in inhibiting haze formation after excimer laser photorefractive keratectomy (PRK) for residual myopia following radial keratotomy (RK). METHODS: A prospective, nonrandomized, noncomparative interventional case series was conducted of 22 eyes (14 patients) with residual myopia after RK performed at a single institution. All eyes were treated with PRK and a single intraoperative topical application of MMC 0.02% solution for 2 minutes using a soaked cellulose sponge placed over the ablated area. Refraction, uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and slit-lamp evidence of corneal opacity (haze) were evaluated over 12 months. RESULTS: Twelve months postoperatively, 3 eyes showed grade 1 haze, and 2 eyes showed grade 0.5 haze. Twelve months postoperatively, 2 (9%) eyes had UCVA ≥20/20. No eye before and 17 (77%) eyes after treatment had UCVA 3*20/40, and no eye before and 9 eyes (40.9%) after treatment had UCVA 2=20/25. Best spectacle-corrected visual acuity was 2=20/40 in all (100%) eyes and 21 (95%) eyes before and after treatment, respectively, and 2=20/25 in 12 (54.5%) eyes before and after treatment. One (4.5%) eye lost 1 line of BSCVA. Mean spherical equivalent refraction achieved was -0.18 diopters (D) (range: -0.75 to +0.50 D) compared to -2.72 D (range: -1.50 to -4.00 D) before treatment. Twelve months after treatment, 19 (85.5%) eyes had a refractive outcome within ±0.50 D. CONCLUSIONS: A single intraoperative application of MMC 0.02% for 2 minutes appears to be effective in preventing subepithelial haze after PRK for residual myopia in patients with undercorrection or regression following RK. [J Refract Surg. 2007;23:226-232.]

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A miopia é uma das maiores causas de cegueira legal em todo o mundo. O déficit visual ocorre em idade precoce, comparado à faixa etária das outras quatro principais causas: catarata, retinopatia diabética, glaucoma e degeneração macular relacionada à idade, que ocorrem décadas depois. Do ponto de vista social, a miopia causa um enorme impacto, pois pode alterar o desempenho de indivíduos na etapa produtiva de suas vidas (1) . Entre as causas de cegueira associadas à miopia predominam as alterações do segmento posterior do bulbo ocular, tais como: descolamento regmatogênico da retina (DR), alterações degenerativas maculares, estafilomas posteriores com ectasia macular, neovascularização sub-retiniana macular, buraco de mácula e glaucoma (2)(3) . A miopia aumenta o risco de DR, além de favorecer o aparecimento precoce da lesão, por causa direta __ pela deficiência da matriz que une os fotorreceptores ao epitélio pigmentado retiniano e/ou pela alteração do mecanismo de bomba do epitélio pigmentado retiniano __ ou por causa indireta __ pelo estiramento da retina, deixando-a suscetível a lesões degenerativas e roturas causadas por uma menor resistência à tração vítreo-retiniana (4)(5)(6) . O DR está associado às degenerações periféricas da retina as quais são identificadas por meio da observação clínica, podendo ser classificadas pela morfologia, prognóstico e predisposição ou não ao DR (7) . A cirurgia refrativa realizada em grande escala é um procedimento recente. Mais recente ainda é a técnica laser in situ keratomileusis (LASIK) que vem se popularizando desde a segunda metade da década passada até hoje. Portanto é escassa a informação existente no que tange à injúria da retina após o LASIK, existindo poucos relatos na literatura que atribuem ao LASIK causa de DR. Como o número de míopes que se submetem ao LASIK é cada vez maior, é natural que entre esses pacientes estejam incluídos aqueles predispostos ao DR, bem como à hemorragia macular e às outras doenças vítreo-retinianas, sendo compreensível que essas anormalidades, e/ou suas exacerbações, sejam associadas ao próprio LASIK (8) . O DR afeta uma pequena percentagem da população geral, dependendo da presença ou ausência de degenerações periféricas retinianas. Na população geral, ocorre na proporção de 1:10.000 por ano. Aproximadamente 40 a Degenerações periféricas da retina do olho míope X LASIK O objetivo deste artigo é apresentar as degenerações periféricas mais comuns na retina dos olhos míopes, discutindo aquelas que oferecem maiores riscos para o descolamento regmatogênico da retina, seu relacionamento com a cirurgia de LASIK e a indicação para o tratamento profilático.

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Purpose: To evaluate the thinnest corneal thickness changes during and after corneal collagen cross-linking treatment with ultraviolet-A irradiation, using hypo-osmolar riboflavin solution in thin corneas. Methods: Eighteen eyes of 18 patients were included in this study. After epithelium removal, iso-osmolar 0.1% riboflavin solution was instilled to the cornea every 3 minutes for 30 minutes. Hypo-osmolar 0.1% riboflavin solution was then applied every 20 seconds for 5 minutes or until the thinnest corneal thickness reached 400 µm. Ultraviolet-A irradiation was performed for 30 minutes. During irradiation, iso-osmolar 0.1% riboflavin drops were applied every 5 minutes. Ultrasound pachymetry was performed at approximately the thinnest point of the cornea preoperatively, after epithelial removal, after iso-osmolar riboflavin instillation, after hypo-osmolar riboflavin instillation, after ultraviolet-A irradiation, and at 1, 6 and 12 months after treatment. Results: Mean preoperative thinnest corneal thickness was 380 ± 11 µm. After epithelial removal it decreased to 341 ± 11 µm, and after 30 minutes of iso-osmolar 0.1% riboflavin drops, to 330 ± 7.6 µm. After hypo-osmolar 0.1% riboflavin drops, mean thinnest corneal thickness increased to 418 ± 11 µm. After UVA irradiation, it was 384 ± 10 µm. At 1, 6 and 12 months after treatment, it was 372 ± 10 µm, 381 ± 12.7, and 379 ± 15 µm, respectively. No intraoperative, early postoperative, or late postoperative complications were noted. Conclusions: Hypo-osmolar 0.1% riboflavin solution seems to be effective for swelling thin corneas. The swelling effect is transient and short acting. Corneal thickness should be monitored throughout the procedure. Larger sample sizes and longer follow-up are required in order to make meaningful conclusions regarding safety.

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BACKGROUND: The capability of the 193-nm excimer laser to ablate the cornea and to remove opacities and various other corneal diseases in a procedure called phototherapeutic keratectomy (PTK) has been demonstrated. In this study we evaluated the long-term results of PTK for treatment of granular and lattice corneal dystrophies. METHODS: Four eyes with granular or lattice corneal dystrophy were treated with a mean followup of 47.8 months (range, 36 to 58 months). Focal ablations of the central cornea with an ablation zone of 5.5 to 6.0 mm were performed. Ablation depth was 110 µt? in three eyes and 140 /on in one eye. RESULTS: Removal of corneal opacities allowed for improvement in corrected visual acuity in all patients. Mean corneal thickness in the area of pathology decreased from 0.583 mm before surgery to 0.449 mm after surgery. Spherical equivalent of the manifest refraction measurements increased by a mean of +5.09 D. There were no major complications, but all patients developed slight haze. There was a hyperopic shift in three eyes. CONCLUSION: Our long-term results suggest that PTK is a safe and effective alternative to penetrating and lamellar keratoplasty in patients with granular or lattice corneal dystrophies. [J Refract Surg 1996;12:795-800]