Scleral suturing of intraocular lenses

This paper describes a simple, safe, and reproducible method for scleral suturing intraocular lenses. The method uses standard tools and equipment.     

Secondary implantation of scleral-fixated intraocular lenses

PURPOSE: To evaluate the results of a large series of secondary implantations using scleral-fixated posterior chamber intraocular lenses (IOLs). SETTING: Bellevue Eye Hospital, Kiel, Germany. METHODS: This retrospective review comprised 624 consecutive patients who had secondary implantation of a posterior chamber IOL with scleral fixation between 1988 and 1995. All patients had been aphakic for at least 1 year. An ab interno or ab externo suture technique through the ciliary sulcus was used. Visual outcome and complications 1 year after surgery were determined. RESULTS: Best corrected visual acuity improved or remained unchanged in 92.0% of eyes; 8.0% lost one or two lines. Intraocular lens decentration of more than 1.5 mm occurred in 1.9% of eyes. Suture erosion was observed in 17.9%, cystoid macular edema in 5.8%, retinal detachment in 1.4%, and vitreous hemorrhage in 1.0%. Severe uveitis occurred in 0.5%. CONCLUSION: Secondary IOL implantation with scleral fixation was a safe procedure. Although there was a small risk of significant complications, more than 90% of patients regained or improved their preoperative visual acuity.     

Age differences in peripheral refractive error.

Refractive error was measured at 0° to 40° temporal to fixation in 10 young adults (M age?=?26 years) and 10 older adults (M age?=?63 years). Older adults exhibited a greater amount of sphere (i.e., overall) error, but no more so in the periphery than in the fovea. Although age differences were small, younger adults were found to exhibit more peripheral astigmatism than the older adults. Discrepancies between obtained results and those of M. Millodot (1985) may be attributed to the relationship between peripheral astigmatism and presenting refractive status. Alternatively, a two-mechanism model of age-related change in lens curvature is capable of accounting for across-study outcome differences. Recommendations are made concerning optimal viewing conditions for the study of age differences in visual perceptual processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complex refractive errors in pediatric patients: cause, management, and criteria for success

BACKGROUND: Uncorrected refractive error in children is an important contributor to permanent neurological visual impairment (amblyopia). Spectacles are often inadequate for certain refractive errors that occur in the pediatric population. Therefore, the purpose of this paper is to present the diagnostic and therapeutic considerations of infants and children referred to a hospital specialty contact lens practice during a 30-month period. METHODS: A retrospective cohort design was used to study patients 12 years or younger referred to a hospital-based contact lens service and cared for by the author. Sixty patients were first examined during the enrollment period. Follow-up data were collected after a period of no less than 3 years from the initial visit. Success with the prescribed therapy was assessed by comparing the final method of optical correction with that prescribed at the initial presentation. RESULTS: Aphakia and trauma were the two most common causes for referral, representing 57% of the patients younger than age 12. Contact lenses were prescribed for 51 of the 60 patients (85%) at presentation. Seventy-five percent of patients with unilateral aphakia attributable to congenital cataract were wearing a contact lens at the most recent follow-up examination. This was reduced to 60% with aphakia after trauma and just 50% with bilateral aphakia. The frequency of a visual acuity of 20/40 or better was 67% for bilateral aphakia, 47% after trauma with aphakia, and 25% for unilateral aphakia. CONCLUSIONS: The results presented here suggest that patients with unilateral aphakia attributable to congenital cataract have the most consistent contact lens wear, followed by patients with unilateral aphakia attributable to trauma. Patients with bilateral aphakia were more likely to have changed to spectacle lens wear. Patients wearing contact lenses at the most recent follow-up examination were more likely to have good visual acuity.     

Contrast sensitivity in patients with silicone intraocular lenses

Meningococcal clone ET-15/37, which appeared as a new one in the Czech Republic in 1993, caused an emergency epidemiological and clinical situation in invasive meningococcal disease, characterized by a high fatality rate (20%) compared to the "normal" fatality rate due to "non ET-15/37" strains. Morbidity rate increased since the first year of the new clone occurrence and reached the peak in 1995. This clone has spread all over the country and investigation of the epidemiological markers of Neisseria meningitidis allowed to quickly recognize the emergency situation and subsequently to provide a targeted vaccination with A + C polysaccharide meningococcal vaccine which prevented the spread of the disease caused by Neisseria meningitidis C. The most frequent phenotype of ET-15/37 clone was C:2a:P1.2(P1.5) and its percentage achieved 80% of group C Neisseria meningitidis strains tested. This antigenic shift of Neisseria meningitidis was associated with the age shift in invasive meningococcal disease morbidity: teenagers started to be the most affected age group and later age group of 1-4 olds followed with high morbidity rates. In 1995 B variant of ET-15/37 clone, B:2a:P1.2(P1.5), appeared, causing a high fatality rate, too. Some data are indicative of a possible decrease in the invasive meningococcal disease incidence in the Czech Republic; nevertheless, the active surveillance and detailed investigation of meningococci have to be continued. After four years following the vaccination and chemoprophylaxis strategy recommended in the Guidelines, set up by the National Reference Laboratory for Meningococcal Infections in 1993, it is possible to conclude, that there have been practically no secondary cases of invasive meningococcal disease in the Czech Republic.     

Determining the imaging quality of intraocular lenses

This paper describes research work motivated by an innovative medical application: computer-assisted transbronchial biopsy. This project involves the registration, with no external localization device, of a preoperative three-dimensional (3-D) computed tomography (CT) scan of the thoracic cavity (showing a tumor that requires a needle biopsy), and an intraoperative endoscopic two-dimensional (2-D) image sequence, in order to provide assistance in transbronchial puncture of the tumor. Because of the specific difficulties resulting from the data being processed, a multilevel strategy was introduced. For each analysis level, the relevant information to process and the corresponding algorithms were defined. This multilevel strategy, thus, provides the best possible accuracy. Original image processing methods were elaborated, dealing with segmentation, registration and 3-D reconstruction of the bronchoscopic images. In particular, these methods involve adapted mathematical morphology tools, a "daemon-based" registration algorithm, and a model-based shape-from-shading algorithm. This pilot study presents the application of these algorithms to recorded bronchoscopic video sequences for five patients. The preliminary results presented here demonstrate that it is possible to precisely localize the endoscopic camera within the CT data coordinate system. The computer can thus synthesize in near real-time the CT-derived virtual view that corresponds to the actual endoscopic view.     

Endoscope-assisted transscleral suture fixation of intraocular lenses

We describe a new method for placing transscleral sutures when fixating posterior chamber intraocular lenses to the sulcus. An intraocular microendoscope with an 18 gauge probe is used for direct sulcus observation and needle position assessment. The straight needle of a 10-0 polypropylene suture and the tip of the probe are placed in a 16 gauge silicone rubber tube to hold them together. Fixing the needle to the endoscope allows a direct view of its tip and requires only one hand. The other hand is used to grasp the tip of the needle when it comes out under the scleral flap after passing through the sulcus. Assessment of needle position with an endoscope avoids surgically induced iris root or ciliary body damage. Fixing the needle to the endoscope simplifies the surgical technique.     

Randomised controlled trial of anterior-chamber intraocular lenses

BACKGROUND: There are an estimated 16 million people blind in both eyes with cataracts. Most live in rural areas of developing countries where surgical resources are scarce. There is no consensus on the most appropriate type of intraocular lens in situations where high-volume low-cost surgery is required. This study was undertaken to evaluate the safety of multiflex open-loop anterior-chamber lenses (ACIOLs). METHODS: 2000 people attending Lahan Eye Hospital, southern Nepal, with bilateral cataracts reducing vision to 6/36 or less were randomly allocated to receive standard surgery--intracapsular extraction (ICCE) with aphakic correction--or ICCE with an ACIOL in their first operated eye. The primary outcome was a visual acuity of less than 6/60 in the operated eye at 1 year follow-up. Visual acuity was measured for 91% of the cohort at 1 year. The sample size was estimated to detect a doubling in poor visual outcome from an estimated rate of 4% in the standard surgery (control) group. FINDINGS: The median (range) time taken to do the surgery was 6.0 (3.0-17.2) min for the ACIOL group and 4.1 (2.4-10.3) min for the control group. 1 year after surgery, 5.0% of the ACIOL group and 5.4% of controls had functional vision less than 6/60 (OR 0.93 [0.60-1.43], p = 0.71). The causes of poor vision in the ACIOL and control groups were: correctable refractive error (22 and 29), uveitis/secondary glaucoma (13 and two), endophthalmitis (four and seven), pre-existing eye disease (four and five), retinal detachment (none and four), cystoid macular oedema (two and none), corneal ulcer (one and one), and corneal decompensation (none and one). INTERPRETATION: This study provides evidence that, in rural areas of developing countries, multiflex open-loop ACIOLs can be implanted safely by experienced ophthalmologists after routine ICCE, avoiding the disadvantages of aphakic spectacle correction. Further follow-up is planned.     

Management of complications in eyes containing two intraocular lenses

OBJECTIVE: To describe the management of complications in eyes containing two intraocular lenses (IOLs). DESIGN: A retrospective noncomparative case series. PARTICIPANTS: Eight patients having a dislocated posterior chamber intraocular lens (PC IOL) and a secondary anterior chamber intraocular lens (AC IOL) participated. INTERVENTION: Surgical treatment of complications, including mobile dislocated PC IOLs in five eyes and retinal detachment in three eyes, was performed. MAIN OUTCOME MEASURES: Visual acuity and anatomic status were evaluated. RESULTS: Dislocated PC IOLs were removed through a pars plana incision in five eyes and a limbal incision in three eyes. Retinal detachments were repaired in three eyes. With follow-up from 7 months to 6.5 years, visual acuities ranged from 20/25 to 20/40 in five eyes and 20/60 to 20/400 in the three eyes undergoing retinal detachment repair. CONCLUSION: Eyes in which dislocation of a PC IOL occurs during or after cataract surgery may have significant complications develop. Successful surgical repair is more complex in the presence of a secondary AC IOL.     

Detection system for ocular refractive error measurement

An automatic and objective system for measuring ocular refractive errors (myopia, hyperopia and astigmatism) was developed. The system consists of projecting a light target (a ring), using a diode laser (lambda = 850 nm), at the fundus of the patient's eye. The light beams scattered from the retina are submitted to an optical system and are analysed with regard to their vergence by a CCD detector (matrix). This system uses the same basic principle for the projection of beams into the tested eye as some commercial refractors, but it is innovative regarding the ring-shaped measuring target for the projection system and the detection system where a matrix detector provides a wider range of measurement and a less complex system for the optical alignment. Also a dedicated electronic circuit was not necessary for treating the electronic signals from the detector (as the usual refractors do); instead a commercial frame grabber was used and software based on the heuristic search technique was developed. All the guiding equations that describe the system as well as the image processing procedure are presented in detail. Measurements in model eyes and in human eyes are in good agreement with retinoscopic measurements and they are also as precise as these kinds of measurements require (0.125D and 5 degrees).     

An evaluation of the biocompatibility of intraocular lenses

BACKGROUND AND OBJECTIVE: The degree of cell adhesion to intraocular lenses (IOLs) was studied through the cell culture system and the morphology of adhering cells was studied using a light electron microscope and a scanning electron microscope. MATERIALS AND METHODS: Human lens epithelial cells were used as materials. The IOL materials were classified into four groups: polymethylmethacrylate (PMMA), heparin surface modified PMMA, surface passivated PMMA, and silicone. RESULTS: PMMA showed greater adhesion than did the other materials. Cells hardly adhered to silicone. Use of a light electron microscope and a scanning electron microscope revealed that cells adhered uniformly to the surface of PMMA and were elongated, but did not adhere uniformly to IOLs of other materials. Only a few cells without the tendency of elongation were noted on the silicone the second day after culture. The 14th day after culture, the surfaces of IOLs, except those of silicone, were covered with cells. CONCLUSION: Such differences in the surface adhesion and morphology of cells adhering to the IOL surface are important in evaluating IOL biocompatibility.     

A new program for calculating intraocular lenses]

A principally new programme is described which overcomes the disadvantages of the usual calculation methods. It is based on the application of each surface of the optical system. The point for the anterior chamber lens is chosen in dependence on the anterior chamber depth; for the posterior chamber lens on the posterior surface of the eye lens. The programme is able to calculate 12 different cases. In each case calculations are made for intraocular lens power, aniseikonia and anisometropia. The calculations are made for possible emmetropia as well as for intended myopia or hypermetropia corresponding to the other eye. The programme can also be used to estimate the effect of mistakes made by measuring the single parameters, for instance: refraction, corneal curvature, eye length, anterior chamber depth. Compared to the SRK II-equation the results of the new programme are much more precise.     

Simplifying scleral fixation of posterior chamber intraocular lenses

We describe a surgical modification for primary scleral fixation of posterior chamber intraocular lenses. The technique keeps intraocular surgical manipulation at a minimum and allows fixation of the lens during accidental rupture of the posterior lens capsule.     

Capsular bag distension after optic capture of a sulcus-fixated intraocular lens

The aim of the present study was to determine the effect of chronic intracerebroventricular infusion of angiotensin II (ANG II) on the expression of brain AT1 receptors in young (3-4 weeks) rats. One week of icv ANG II infusion produced a significant increase in brain AT1 receptor protein (Western blot) and mRNA (relative RT-PCR) expression. These data raise the possibility that ANG II may play a role in postnatal expression of brain AT1 receptors.     

Scanning electron microscopic characteristics of small-incision intraocular lenses

PURPOSE: To evaluate the surface characteristics of commonly used, small-incision, intraocular lenses (IOLs). METHODS: Representative samples of five groups of foldable IOLs (4 silicone and 1 acrylic) underwent surface and edge-finish examination using a slit lamp. The IOLs were folded using a folding block and forceps. All the IOLs then were examined using a scanning electron microscope. A one-piece polymethylmethacrylate IOL was used for comparing surface-finish characteristics. The IOLs were examined for optic surface quality, edge finish, haptic, haptic/optic junction, and possible post-folding modifications. RESULTS: Slit-lamp evaluation of the surface quality of all of the silicone lenses demonstrated a smooth finish of the optic surface, edge, and haptics. Scanning electron microscopic analysis of the IOLs demonstrated adequately finished haptics or footplates and optics. Excess molding flash was seen on the edges of the some of the silicone IOLs, and no molding flash was observed on others. The acrylic IOL had a somewhat sharper optic edge. Irregular finish of the haptic/optic junctions of some of the IOLs (both silicone and acrylic) was noted. CONCLUSIONS: Currently available foldable IOLs have demonstrated adequate lens finish. However, irregularities of the haptic/optic junctions and molding flash are present on most IOLs evaluated, indicating room for improvement in the finish of foldable IOLs. Phacoemulsification with capsular bag IOL placement may decrease the clinical significance of these relatively subtle lens finish irregularities.     

Corneal endothelial damage from previously implanted intraocular lenses

Intraocular lenses which had been surgically removed from human eyes were compared to new uncoated IOLs with regard to damage caused by dynamic and static contact with fresh rabbit corneal endothelium. Previously implanted IOLs caused consistently less endothelial damage. Possible mechanisms and the implications of these findings for the corneal surgeon doing pseudophakic keratoplasty are discussed.     

Early central posterior capsular fibrosis in sulcus-fixated biconvex intraocular lenses

A series of 228 eyes implanted with one-piece all poly(methyl methacrylate) (PMMA) biconvex posterior chamber intraocular lenses was examined for posterior capsule opacification. One hundred forty-one eyes (61.8%) had opacification at an average postoperative period of 19.7 months. Seventy eyes (30.7%) developed an unusual form of early central posterior capsular fibrosis (ECPCF), which was confined to the capsulorhexis opening, sparing the peripheral aspect of the anterior and posterior capsules. Risk factors for developing this form of opacification were close apposition of peripheral anterior and posterior capsules caused by placing a posteriorly vaulted biconvex optic anterior to a capsulorhexis opening smaller than the optic diameter. This opacification occurred most often in cases of haptic fixation in the ciliary sulcus. The cumulative capsulotomy rate in this series was 5.26% at three months, 9.1% at 12 months, and 13.2% at 20 months. Of the ECPCF cases, 34.3% eventually required neodymium: YAG (Nd:YAG) laser capsulotomy; the capsulotomy rate for ECPCF was 4.8 times higher than that for Elschnig pearls. Early onset of ECPCF (average onset = 19.4 weeks) resulted in early Nd:YAG capsulotomy (average = 8.0 months after surgery). One-piece all-PMMA biconvex intraocular lenses may promote early central fibrosis of the posterior capsule if the lens optic is anterior to a capsulorhexis opening smaller than the optic diameter. The early onset of this form of opacification predisposes to earlier Nd:YAG capsulotomy with a higher risk of complications.     

Microbiological examination of bandage soft contact lenses used in laser refractive surgery

BACKGROUND: Disposable soft contact lenses are known to be colonized by bacteria and play a key role in bacterial keratitis pathogenesis. Such lenses, commonly used after laser refractive surgery procedures in which postoperative corneal infiltrations are sometimes observed, are potentially a substrate for bacterial inoculation. This study evaluates the extent of such a contamination. METHODS: Sixty disposable lenses collected from 60 eyes of patients who underwent photorefractive keratectomy (PRK), photoastigmatic refractive keratectomy (PARK), or laser in situ keratomileusis (LASIK) for the treatment of myopia or hyperopia were collected under sterile conditions over 4 months and cultured in various media. Results were statistically analyzed and the correlation with clinical and epidemiological data was examined. RESULTS: Eleven (18.3%) of the examined lenses were contaminated with Staphylococcus epidermidis. No other bacteria or fungi were found. Contamination was significantly more common among female patients (P = .036). Correlation with the other clinical or operative parameters examined was statistically insignificant. CONCLUSIONS: Contamination was independent of the surgical procedure and females who were frequent users of eyelid cosmetics displayed higher contamination frequencies, suggesting that bacteria possibly originate from eyelid flora. The isolation of Staphylococcus epidermidis requires close postoperative surveillance, since it is a known cause of keratitis. Prophylactic postoperative treatment with tobramycin, gentamycin, or sulphonamides could be indicated.     

Damage of foldable intraocular lenses by incorrect folder forceps

Patients presenting with ischemic chest pain and electrocardiographic evidence of global T-wave inversion are most frequently women with intact left ventricular function and no critical stenosis of major coronary vessels. Hence, this syndrome has a good immediate and long-term prognosis.