European Journal of Implant and Refractive Surgery最新文献

Cataract extraction in uveitis is still controversial. In this brief review, preoperative and postoperative problems as well as functional results are described. Special emphasis is placed on the question of intraocular lens (IOL) implantation. The procedure of cataract extraction and the postoperative course is mainly influenced by the underlying type of uveitis.

Objective: To determine if an intraocular lens (IOL) with a high A constant reduced the incidence of retinal detachment following YAG laser capsulotomy. Study Design: Patients had to have a minimum of 1 year follow-up following a YAG capsulotomy. This is a retrospective analysis of a consecutive series of 254 YAG lasers. Setting: An out-patient clinical practice. Main Outcome Measures: Incidence of retinal detachment and A constant of the IOLs used for the primary cataract surgery. Results: Zero percent incidence of retinal detachment in patients with IOLs having an A constant of 118.5 or greater (103 patients) and 4.8% incidence of retinal detachment of patients having an IOL of less than 118.5 (42 patients) (P = 0.08%). Conclusions: This study shows a definite trend towards a reduced rate of retinal detachment with high A-constant IOLs. In order to achieve a 90% confidence level it is necessary to have 450 patients in each group in order to compare the data. A multi-centre study is underway to achieve this.

Objectives: To assess the main risk factors for complications in phacoemulsification performed by an experienced surgeon. Study Design: Two hundred and fifty phacoemulsification procedures performed during a 1-year period were analysed. Most of them were done by 5 mm incisions, under conjunctival flap with no suture. Setting: Eye Clinic, University of Verona, Italy. Main Outcome Measures: Intraoperative complications: anterior and posterior capsular tears, vitreous loss, iris damage, corneal damage. Postoperative complications: inflammation, fibrinous reactions, endothelial damage, astigmatism, surgical reinterventions. Results: Intraoperative complications were 3.8%. They were related to: pupil diameter less than 3 mm (P < 0.001), use of a diaphragmatic pump (P < 0.001), presence of hard nucleus (P < 0.001). Postoperative complications were 6.5%. They were related to: intraoperative complications (P < 0.001), pupil diameter less than 5 mm (P < 0.001), low endothelial cell count (P < 0.01). Two sutured incisions required resuturing in the postoperative period. Conclusions: Phacoemulsification has become a very safe procedure in normal cataractous eyes. Eyes with advanced cataracts or additional pathologies are still at increased risk for complications.

Techniques for assessing corneal topography have been developed and improved over the last four centuries in response to changing demand. In recent years, there has been an escalation in the number, type and complexity of the systems available, following a trend which may continue into the future.

Most widely-available topography systems are based on the principle of reflection (videokeratoscopy), although there is now an increasing number of systems based on the principle of projection (rasterstereography, moiré interference and laser interferometry). Each technique has its own inherent advantages and limitations. For example, those based on projection can directly measure true corneal height and be used in the individualized treatment of irregular corneal astigmatism.

Most systems rely upon computer algorithms to convert recorded images into topographic information. New algorithms incorporating fewer estimates and assumptions are being developed, in order to improve the accuracy with which the corneal surface can be reconstructed.

The topographic data of individual patients can be displayed visually in the form of maps, but the need to analyse grouped data has lead to the development of quantitative descriptors of corneal shape, and indices predicting visual function. Classifications of normal and abnormal topography based on pattern recognition have been described, but await improvements in artificial neural networks before they can be automated. Advanced computing is also needed before data analysis is sufficiently rapid for real-time topography to become a reality. Future developments in corneal topography need to target the differing requirements of research and clinical practice.

Objective: To assess postoperatively the position of the haptics of the scleral fixated posterior chamber intraocular lenses (IOLs), in order to improve precision in scleral fixation. Study Design: A number of 12 patients (16 IOLs) were studied postoperatively by ultrasound biomicroscopy (UBM). The STC-6 straight needle was used for scleral fixation, with different techniques. In addition, 8 aphakic eyes selected for secondary implantation were studied. Setting: University Eye Clinic, Verona, Italy. Main Outcome Measures: The position of the loops in the suture of the scleral fixation was determined. This position was related to the surgical technique and to the distance between the emergence of the sutures and the limbus. The status of the posterior chamber was studied in aphakic eyes. Results: Out of the 32 loops, 24 were located in the pars plana, 6 were located in the ciliary sulcus, and 2 were located in the iris root. After ab interno fixation (9 eyes), with a suture to limbus distance of 2–3 mm, all but 2 loops were posterior to the ciliary sulcus. After ab externo fixation (7 eyes), with a suture to limbus distance of 1.5–2 mm, 6 loops were in the pars plana, 6 were in the ciliary sulcus and 2 loops were against the iris root. Most aphakic eyes showed some anatomical impairment of the posterior chamber. One eye showed ciliary body detachment. Conclusions: Suture to limbus distances of about 1 mm should be adopted for scleral fixation. Reversed fornix based scleral flaps could improve precision. However, we must emphasize that posterior synechiae or ciliary processes may obstruct the access to ciliary sulcus in aphakic eyes. The UBM study is very useful in eyes selected for secondary implantation.

Aim: To describe a new device, the Maastricht topographer (MT), which uses the principle of moire interference, to measure corneal shape. Methods: The Maastricht Topographer (MT) projects two sinewave gratings onto the tearfilm in quick succession, and by local analysis of grating intensity in the image so formed, reconstructs the true corneal shape in terms of height from a reference plane. A total of 262 144 data points are measured in an area 21.5 × 14.5 mm. During a one year period, patients referred for topography had measurements made by the MT and a videokeratoscope. Three cases were selected to demonstrate the advantages of the MT. Results: Image acquisition by the MT was straightforward, with alignment and focusing being of less importance than in videokeratoscopes. It provided detailed topographic information from the whole corneal area, and from irregular or non-reflective surfaces. The initial reconstruction of the true corneal shape was expressed in terms of height, from which measurements of slope, curvature and power were derived directly. Conclusions: Height reconstructions made by the MT are particularly useful in certain corneal pathologies and in evaluating the corneal profile after photorefractive keratectomy. Measurement of the ablation surface immediately postoperatively is essential in the study of ablation profiles and postoperative wound healing.

Objective: To assess the intensity of pain after applying some modifications in the surgical steps undertaken during the course of planned extracapsular cataract extraction under topical anaesthesia with Van Lint block. Study Design and Patients: This is a prospective study of 20 patients divided into 2 groups. Fifteen patients had previous extracapsular cataract extraction in 1 eye under retrobulbar anaesthesia (group 1). Those were chosen to compare the difference in their perception of pain under retrobulbar anaesthesia vs topical anaesthesia using these surgical modifications. Group 2 was initially made of 15 patients who had no previous ocular surgery and had no preference for the type of anaesthesia. They were chosen to outline their response to topical anaesthesia. This would have made the total of 30 patients, however, it was felt that the first 10 patients of this group did not have the benefit of all the surgical modifications and their responses would distort the results. Therefore, only the responses of the last 5 who benefited from the modifications were included. Setting: The Eye Department, Pilgrim Hospital, Boston, Lincolnshire, UK. Main Outcome Measures: Single dose of 0.5 ml preservative free Xylocaine 4% drops in the conjunctival sac with the lids maintained open for up to 1 min immediately preoperatively gives complete anaesthesia of the cornea and conjunctiva. A ‘clear corneal incision’, a wide ‘can-opener capsulotomy’, and ‘equatorial flush’ are surgical modifications required to abolish any feeling of pain in planned extracapsular cataract extraction under topical anaesthesia. Results: The severity of the pain was graded from 0–4. Eight patients had no pain, 5 patients had grade 1 and 7 patients had grade 2 pain. No patients graded 3 or 4. Conclusions: Xylocaine 4% preservative-free drops produce complete corneal anaesthesia and decrease the palpebral reflex when applied immediately before the start of surgery for 30–60 s while the lids are held apart—allowing complete immersion of the ocular surface under a layer of drops. Corneal section and wide capsulotomy are surgical steps that prevented pain during nucleus delivery. Equatorial flush speeds aspiration/irrigation. Pain was caused during suturing the posterior lip of the incision involving the conjunctiva if the surgery took longer than expected.