In normal subjects, the contribution of the anterior cornea to the overall ocular aberration remains reasonably stable over the normal interblink interval (approximately 4 seconds) but rises to levels which could perceptibly degrade retinal image quality under circumstances where the interblink interval is increased to exceed 10 seconds, as may occur during the use of visual display screens or when performing difficult tasks.

A significant induction of corneal HOAs still exists with the latest generation Schwind excimer laser. Linear regression analysis will help predict postoperative asphericity obtained when using LASIK for the correction of high myopia.

The 2-step technique improved the accuracy of excimer laser correction of post-PKP astigmatism.

Lipid peroxides are thought to be formed by free radicals and have been implicated in the pathogenesis of diabetes complications. A convenient and sensitive method for estimation of lipid peroxide concentration is the quantitative estimation of their metabolic end-product malondialdehyde (MDA) expressed in mmol/L using the thiobarbituric acid test (TBA-test). We have measured the serum concentrations of MDA in 60 well controlled type I diabetic patients (28 without retinopathy and 32 with retinopathy) and 13 age-matched healthy subjects. Patients with retinopathy showed significantly increased MDA level (2.65+/-1.00) compared to diabetics without retinopathy (1.80+/-0.81) and healthy controls (1.47+/-0.45). The serum levels of MDA correlated best with glycosylated haemoglobin (r=0.28), serum triglyceride concentration (r=0.29) and serum cholesterol concentration. (r=0.47). Increased lipid peroxides suggesting increased free radical activity is associated with retinopathy and this may have pathogenetic implications.

In this study the incidence of Demodex in patients with blepharitis was very high, when compared with normal subjects, showing a clear association between blepharitis and Demodex infestation. Treatment with mercury oxide ointment was satisfactory in controlling the infection, despite difficulty in its application and occasional toxicity.

Aim: To study the anatomical and visual performance following implantation of a model of artificial cornea and to evaluate the postoperative long term complications. Methods: 11 eyes of 11 patients with bilateral corneal blindness considered as potentially having high risk of failure of penetrating corneal keratoplasty were implanted with biocolonisable Kpro keratoprosthesis (BIOKOP I, FCI, Rantigny, France) in the period between January 1996 and May 1998. Only one eye was implanted in all patients and followed up for a period of 60 months. The visual outcome, anatomical and functional stability, complications, and the general performance of the keratoprosthesis were evaluated. Results: The keratoprosthesis (BIOKOP I) only 36.3% remained in position to date. In the patients' last visit five eyes (45.4%) were blind and one (9.0%) showed a slight improvement in the best corrected visual acuity (BCVA) in comparison to preoperative tests. Six eyes (54.5%) showed improved BCVA before having postoperative complications. Four eyes underwent replacement of a BIOKOP I Kpro with a BIOKOP II as a result of extrusion. The keratoprostheses remained anatomically in situ for a mean of 25.5 months and their functional performance period was limited to a mean of 22 months. Conclusion: Corneal keratoprosthesis (BIOKOP I, II) does not provide a stable anatomical relation with the surrounding ocular structures. Its ability to restore vision is limited to a short postoperative period in eyes implanted with severe ocular surface disease.

In order to ascertain the accuracy and specificity of the Potential Acuity Meter (PAM) in the preoperative evaluation of likely postoperative visual acuity in cases of cataract associated with age-related macular degeneration (ARMD), we studied the results in 130 cases, 54 of whom had preoperatively proved or suspected ARMD associated with a cataract. All of them were operated with extracapsular extraction and implantation of an intraocular lens (IOL), and final visual acuity was established when all the patients were visited three months postoperatively. A positive linear correlation was found between normal ocular fundus and PAM prediction (r = 0.77), and in the group of patients with preoperatively confirmed ARMD (r = 0.77). No difference was found between the preoperative PAM estimation and the final visual acuity in both groups. The PAM prediction was less accurate in cases with doubtful preoperative ARMD (r = 0.58) for whom showed PAM the highest score of false negatives in favor of the final visual acuity. Our results show that PAM is a reliable clinical technique for the prediction of visual results after cataract surgery in cases with preoperatively proved or doubtful macular pathology. To the best of our knowledge, this is the first report regarding the sensitivity and specificity of the PAM in diseased or suspicious maculas associated with cataract.

RESUMENObjetivo: Revisar el resultado de los trasplantes de limbo (TL) realizado en pacientes con Síndrome de insuficiencia límbica (SIL) en el contexto de varias enfermedades de la superficie ocular. Materiales y métodos: Se realizó un estudio retrospectivo y multicéntrico (cinco centros) de los TL realizados entre 1996 y 2004. Los datos fueron recogidos por el mismo investigador, en una base de datos especialmente diseñada para el estudio. Se consideró como «éxito» del TL a la ausencia de: defectos epiteliales, inflamación y recurrencia del pterigión cuando éste fue la causa del TL. Resultados: Se analizaron un total de 72 TL realizados en 61 pacientes (65 ojos) con tiempo de seguimiento de 20,8 meses (DS 23,5; rango,. Hubo 33 hombres y 28 mujeres, con una media de 55,8 años (DS: 15,6; rango, was performed. Data were collected by the same researcher using a customized database. Success was defined by the absence of a persistent corneal epithelial defect, on-going inflammation or recurrence of a pterygium. Results: Data from 72 LT performed in 61 patients (65 eyes) with a mean follow-up of 20.8 months (SD 23.5; range, 3-115) were analyzed. There were 33 males and 28 females with a mean age of 55.8 years (SD: 15.6; range, 20-89). Fifty-eight (80.6%) LT were autografts (40 pterygia, 12 alkali burns, 3 iatrogenic cases, 2 viral infections, 1 neoplasia case) and 14 (19.4%) were allografts from cadave-