[Undersurface ablation of the corneal flap for LASIK enhancement]. / Retratamientos en cara interna del colgajo corneal en LASIK. Estudio comparativo con un grupo control.

OBJECTIVE: To study the efficacy and safety of retreatment in LASIK surgery, comparing under surface ablation of the corneal flap and stromal bed ablation techniques. METHODS: The patients studied were those who had LASIK enhancement because of a residual negative refractive error, and were divided in two groups: a Control group of 14 eyes that had ablation of the residual stromal bed and a Study group of 14 eyes that had ablation of the undersurface of the flap. In the Study group we included patients in whom we calculated that the post-enhancement treatment of the residual stromal bed would be less than 300 microns. We compared the refraction, visual acuity and cornea pre and post-retreatment, three months later. RESULTS: Prior to retreatment, both groups were similar and no statistically significant differences were found in age, sex, pachymetry, corneal curvature or residual refraction. Ablation was 21.5 (SD 11) microns in study group and 22.6 (SD 7) microns in control group (p=0.796). Post-retreatment refraction was statistically lower in both groups than before the procedure (p<0.01), however there were no differences between the control and study groups. Visual acuity improved after retreatment in both groups (p<0.01) but no statistically significant differences were found between control and study groups. No patient lost two lines of visual acuity. We observed slight alterations in the corneal flap in both groups. CONCLUSIONS: In our study, the undersurface retreatment technique produced similar results to those achieved using conventional stromal bed techniques with both being effective and safe in patients with a small residual negative refractive error.

Retratamientos en cara interna del colgajo corneal en LASIK. Estudio comparativo con un grupo control / Under surface ablation of the corneal flap for Lasik enhancement

Objetivo: Estudiar la eficacia y seguridad de los retratamientos en cirugía LASIK comparando el tratamiento sobre el lecho estromal con el tratamiento sobre la cara interna del colgajo corneal. Métodos: Pacientes intervenidos mediante LASIK con defecto residual negativo sometidos a retratamiento divididos en dos grupos. Grupo control: 14 ojos tratados sobre lecho estromal. Grupo estudio: 14 ojos tratados sobre cara interna del colgajo. En el grupo estudio se incluyeron aquellos pacientes en los que se preveía que el grosor del lecho post-retratamiento sería inferior a 300 micras. Se evaluaron la refracción, la agudeza visual y la córnea pre y postretratamiento a los 3 meses del retratamiento. Resultados: Antes del retratamiento no había diferencias entre ambos grupos en lo referido a edad, sexo, paquimetría, curvatura corneal y defecto de refracción. La ablación fue de 21.5 DE 11 en el grupo estudio y 22,6 DE 7 micras en el control (p=0,796). La refracción post-retratamiento fue significativamente menor en ambos grupos que antes (p<0,01). No hubo diferencias entre el grupo control y el estudio. La agudeza visual final mejoró con respecto a la que presentaban antes del retratamiento en ambos grupos (p<0,01). No hubo diferencias entre ambos grupos. Ningún paciente perdió dos líneas de agudeza visual. Se observaron leves alteraciones en el colgajo corneal en ambos grupos. Conclusiones: En nuestro estudio la técnica de retratamiento sobre la cara interna del colgajo es similar en eficacia y seguridad a la técnica convencional sobre el lecho estromal en defectos negativos con poco defecto residual

Objective: To study the efficacy and safety of retreatment in LASIK surgery, comparing under surface ablation of the corneal flap and stromal bed ablation techniques. Methods: The patients studied were those who had LASIK enhancement because of a residual negative refractive error, and were divided in two groups: a Control group of 14 eyes that had ablation of the residual stromal bed and a Study group of 14 eyes that had ablation of the undersurface of the flap. In the Study group we included patients in whom we calculated that the post-enhancement treatment of the residual stromal bed would be less than 300 microns. We compared the refraction, visual acuity and cornea pre and post-retreatment, three months later. Results: Prior to retreatment, both groups were similar and no statistically significant differences were found in age, sex, pachymetry, corneal curvature or residual refraction. Ablation was 21.5 (SD 11) microns in study group and 22.6 (SD 7) microns in control group (p=0.796). Post-retreatment refraction was statistically lower in both groups than before the procedure (p<0.01), however there were no differences between the control and study groups. Visual acuity improved after retreatment in both groups (p<0.01) but no statistically significant differences were found between control and study groups. No patient lost two lines of visual acuity. We observed slight alterations in the corneal flap in both groups. Conclusions: In our study, the undersurface retreatment technique produced similar results to those achieved using conventional stromal bed techniques with both being effective and safe in patients with a small residual negative refractive error

La oftalmología en los ojos de los higienistas del siglo XIX

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Platelet function in diabetic retinopathy: levels of beta-thromboglobulin and platelet factor 4.

Altered platelet function has been reported in diabetic patients. This article reports plasma levels of beta-thromboglobulin and platelet factor 4 as measures of in vivo platelet activity in diabetic and control groups. Both beta-thromboglobulin and platelet factor 4 were significantly higher in diabetics than in controls (p < 0.01). The levels observed were not significantly affected by age, sex, diabetes type or whether the diabetic had nonproliferative or proliferative retinopathy, but beta-thromboglobulin levels were significantly higher in diabetics of less than 10 years standing than in those who had suffered diabetes for over 20 years (p < 0.05).

Treatment of diabetic neovascular glaucoma by panretinal ablation and trabeculectomy.

The efficacy of treating diabetic neovascular glaucoma by panretinal cryotherapy and trabeculectomy was studied over post-operative periods of 6-24 months in 26 selected eyes (8 acute cases and 18 chronic cases). The only complications attributable to surgery were slight hyphemas. Mean pre-operative intraocular pressure (IOP) among the acute cases was 48.8 +/- 9.9 mmHg. After 1 year, IOP was under control (IOP less than or equal to 22 mmHg) in 6 eyes (75%) (2 patients needed hypotensive drugs and another required surgery again). Among the chronic cases, pre-operative IOP was 30.1 +/- 2.1, while a year after surgery IOP was under control (IOP less than or equal to 22 mmHg) in 14 patients (77%) (5 of these needed hypotensive medication and 2 a second operation). The visual acuity (VA) of 66% of the chronic cases was unaltered a year after surgery. The VA of 63% of the acute cases was better a year after surgery. The VA of the 8 patients re-examined 2 years after surgery had deteriorated in spite of their IOP being under control.