Current status of limbal conjunctival autograft.

The past decade has witnessed several major advances in the field of ocular surface reconstruction. It is now established that the limbal and corneal epithelia belong to the same clonogenic lineage and that conjunctival transdifferentiation does not occur. These facts have engendered the increasing use of limbal transplantation in several ocular conditions involving limbal compromise. Many reports on this procedure have been published in the past year. They add to the growing body of evidence that limbal transplantation is efficacious in replenishing the stem cell pool, promoting improved vision and enhancing ocular comfort. Recent clinical studies on limbal autograft transplantation also underscore the importance of preoperative impression cytology in donor eyes, highlight the fact that transplantation in inflamed eyes is to be avoided, and indicate that the procedure is likely to provide better outcomes if performed several months after ocular surface burns. The appreciation of the utility of amniotic membrane transplantation in ocular surface reconstruction has provided a surgical tool to use in tandem with limbal transplantation. Questions such as why limbal autografts fail, the long-term results of LAT, and whether limbal inclusion is mandatory during conjunctival transplantation after pterygium excision have not been answered fully. Studies on long-term outcomes with limbal allograft transplantation and those reporting on experience with newer techniques such as epithelial transplantation using tissue culture-cultivated epithelium are likely to provide better perspectives on the best way to reconstruct the ocular surface in stem cell-deficient eyes.

Use of ultrasound biomicroscopic evaluation in preoperative planning of penetrating keratoplasty.

PURPOSE: To evaluate the use of ultrasound biomicroscopy (UBM) in examining the status of anterior-segment structures in eyes with corneal opacification. METHODS: Evaluation with UBM was performed between 1 and 2 weeks before surgery in 21 patients (21 eyes) with corneal opacities who were scheduled for penetrating keratoplasty. UBM findings were correlated with the findings noted during penetrating keratoplasty. The efficacy of UBM evaluation was calculated in terms of positive and negative predictive values (PPVs and NPVs) for the presence or absence of each finding. RESULTS: Seventeen eyes had either aphakic or pseudophakic bullous keratopathy (ABK or PBK). UBM findings of anterior synechiae, peripheral anterior synechiae, posterior synechiae, peripheral and sector iridectomies positively correlated with those observed during surgery in five (55.6%) of nine locations, 19 (73.1%) of 26 locations, 12 (80%) of 15 locations, eight (88.9%) of nine locations) and six (85.7%) of seven locations, respectively. The NPVs for these findings were 100%, six (54.5%) of 11 locations), 10 (71.4%) of 14 locations, 12 (100%) of 12 locations, and 14 (100%) of 14 locations, respectively. Correlation for findings pertaining to the posterior capsule (PC) were presence of PC/PC remnants [PPV, 13 (92.9%) of 14 locations; NPV, two (66.7%) of three locations], presence of central PC tears [PPV, two (66.7%) of three locations], intactness of PC [PPV, six (85.7%) of seven locations], and PC thickening [PPV, 13 (81.25%) of 16 locations; NPV, four (100%) of four locations]. For vitreous in the anterior chamber, the PPV was eight (100%) of eight locations, and NPV was 12 (92.3%) of 13 locations. Pseudophakos-related information in eyes with PBK showed a PPV of 100% for presence, centration, and anatomic location (seven of seven, four of four, and seven of seven locations, respectively). CONCLUSION: In eyes with corneal opacity, UBM determines the status of various anterior-segment structures. It is thus a useful adjunct in the preoperative planning and prognostication of patients requiring penetrating keratoplasty.

Laser cataract surgery.

Lasers have been investigated for cataract removal for nearly two decades. The technology has now reached a stage at which cataract can indeed be removed entirely with laser alone. Neodymium:yttrium-aluminum-garnet and erbium:yttrium-aluminum-garnet are the laser sources being utilized at the present time by manufacturers of laser cataract surgery systems. Initial clinical experience reported in the literature has served to highlight both the laser's capabilities and areas that need further refinement. Despite the thrill associated with the availability of this alluring new technology for cataract removal, laser systems with higher efficiency and innovative surgical techniques to optimally utilize their capabilities are necessary if laser cataract surgery is to be an improvement over current techniques.

Heparin-surface-modified intraocular lenses in pediatric cataract surgery: prospective randomized study.

PURPOSE: To evaluate the performance of heparin-surface-modified (HSM) intraocular lenses (IOLs) in pediatric eyes after cataract surgery. SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: This prospective, randomized, double-masked, controlled clinical trial comprised 90 children aged 2 to 14 years with cataract. The patients were consecutively randomized to receive an HSM (Group 1) or an unmodified (Group 2) poly(methyl methacrylate) (PMMA) IOL. Extracapsular cataract extraction (ECCE) with IOL implantation was performed in children 8 years and older and ECCE with primary posterior capsulotomy, anterior vitrectomy, and IOL implantation in children younger than 8 years. Outcome parameters were inflammatory cell deposits on the IOL surface, posterior synechias, and anterior chamber reaction. RESULTS: Follow-up data were available for 73, 70, 60, and 68 patients at 1 week, 1 month, 3 months, and 6 months, respectively. Significantly fewer cell deposits were noted in Group 1 at 1, 3, and 6 months (P < .001). Synechia formation and anterior chamber reaction were comparable in the 2 groups. CONCLUSION: The lower incidence of inflammatory cell deposit formation in eyes with HSM PMMA IOLs indicates that these IOLs have greater bicompatibility than unmodified IOLs in pediatric cataract surgery.

Unusual intermediate-term outcome in three cases of limbal autograft transplantation.

OBJECTIVE: To report an unusual intermediate-term outcome after limbal autograft transplantation for unilateral, severe chemical burns. DESIGN: Case reports of three consecutive cases. PARTICIPANTS: Three patients with a history of chemical burns. The fellow eye was clinically uninvolved in all patients. Surgery was indicated for conjunctivalization (cases 1 and 3) and persistent epithelial defect (case 2). INTERVENTION: Three (cases 2 and 3) or four (case 1) 1.25-clock-hour-wide limbal grafts were harvested from the fellow eye and transplanted to the limbus in the affected eye. Surface re-epithelialization, improvement in visual acuity, and maintenance of surface stability were monitored. RESULTS: Limbal grafts were effective in re-epithelialization of the corneal surface within 4 weeks in all cases. Symptomatic relief and improvement in visual acuity were noted during early follow-up. However, a progressive conjunctival ingrowth that tended to override the grafts and encroach the visual axis was noted over the course of a year in all three recipient eyes. CONCLUSIONS: Limbal autograft transplantation is an effective method for surface re-epithelialization in strictly unilateral chemical burns. Caution should be exercised in case selection. The authors' experience suggests a variable degree of attenuation in viability of transplanted limbus. Close follow-up of operated eyes is necessary to determine the long-term efficacy of limbal transplants as a source of corneal phenotypic cells.

Different faces of the white cataract: a phaco surgeon's perspective.

PURPOSE: To develop a system of categorizing white cataracts so that the salient features, as would be pertinent to phaco-emulsification surgery, could be recognized pre-operatively. METHODS: Patients with total cataracts were carefully evaluated using slit-lamp biomicroscopy and slit-lamp photography. An attempt was made to determine whether pre-operative evaluation could ascertain the presence or absence of features of these cataracts that often cause surgical difficulties, namely, increased intralenticular pressure (ILP), milky cortex and brown nuclear colour. RESULTS: Using a standardized method of biomicroscopic evaluation, it was found that the status of the ILP, cortex and nuclear colour could be determined consistently. Surgical strategies based on such a system of categorization has permitted white cataracts to be consistently managed using phacoemulsification. CONCLUSIONS: Systematic pre-operative evaluation and categorization of white cataracts based on the ILP, status of the cortex and nuclear colour can permit proper surgical planning and successful management of such cases with phacoemulsification.

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

Capsular bag distension from occlusion of the circular anterior capsule opening by the intraocular lens (IOL) optic is a rare complication of capsulorhexis. The nature and source of fluid remain unclear. We report a case of capsular bag distension in an eye with an optic-captured, all-poly(methyl methacrylate), sulcus-fixated IOL. The fluid behind the IOL optic was visible on the first postoperative day and resolved spontaneously by the sixth postoperative week. We believe that retained viscoelastic material in the capsular bag was a major contributor to the fluid.

Laser-assisted cataract surgery and other emerging technologies for cataract removal.

As we near the end of this century, refractive cataract surgery has become a reality through concerted contributions from ultrasonic phacoemulsification, foldable intraocular lens (IOL) implantation technology and keratorefractive surgery. As we enter the new millennium, our sights are set on realizing another dream: accommodative IOL surgery. Towards achieving this goal, many advances have been made in both techniques and technology of cataract removal. Lasers in particular have been under investigation for cataract removal for nearly two decades. The technology has now reached a stage where cataract can indeed be removed entirely with laser alone. Neodymium:YAG and erbium:YAG are the laser sources currently utilized by manufacturers of laser phaco systems. Initial clinical experience reported in the literature has served to highlight the capabilities of lasers and the need for further refinement. Despite the excitement associated with the availability of this alluring new technology for cataract removal, it is necessary to develop more effective laser systems and innovative surgical techniques that optimize its capabilities if laser phaco surgery is to be a genuine improvement over current techniques.

Prospective evaluation of corneal endothelial cell loss after pediatric cataract surgery.

PURPOSE: To study the alterations in endothelial cell count and morphology after pediatric cataract surgery using currently practiced techniques. SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: In a prospective nonrandomized series comprising 20 eyes of 14 children with congenital or developmental cataract, endothelial cell loss from cataract surgery was evaluated. Mean patient age was 9.3 years (range 5 to 15 years). Extracapsular cataract extraction (ECCE) with intraocular lens (IOL) implantation was performed in 11 eyes (Group 1). Primary posterior capsulotomy and anterior vitrectomy were performed with ECCE and IOL implantation in 9 eyes (Group 2). Noncontact specular microscopy was done preoperatively and 6 to 8 and 24 to 36 weeks postoperatively. Endothelial cell loss, alteration in the coefficient of variation, and the change in the number of hexagonal cells were determined by semiautomated analysis of endothelial pictures. RESULTS: Mean endothelial cell loss was 198.39 cells/mm2 (5.28%) in Group 1 and 295.17 cells/mm2 (7.50%) in Group 2 at 24 to 36 weeks. There was no statistically significant difference in alteration in endothelial cell count and morphology between the 2 groups. CONCLUSIONS: The results suggest that endothelial cell loss with currently practiced techniques of pediatric cataract surgery is within acceptable limits.

Autosomal dominant zonular cataract with sutural opacities is associated with a splice mutation in the betaA3/A1-crystallin gene.

PURPOSE: Congenital cataracts constitute a morphologically and genetically heterogeneous group of diseases that are a major cause of childhood blindness. Autosomal Dominant Zonular Cataracts with Sutural Opacities (CCZS) have been mapped to chromosome 17q11-q12 near the betaA3A1-crystallin gene (CRYBA1). The betaA3A1-crystallin gene was investigated as the causative gene for the cataracts. METHODS: The betaA3/A1-crystallin gene was sequenced in affected and control individuals. Base changes were confirmed and assayed in additional family members and controls using NlaIII restriction digestion of PCR amplified DNA sequences. Base changes were assessed for their effects on splicing by information analysis. RESULTS: The cataracts are associated with a sequence change in the 5' (donor) splice site of intron 3: GC(g->a)tgagt. The sequence change also creates a new NlaIII site. This base change cosegregates with the cataracts in this family, being present in every affected individual. Conversely, this base change was not seen in 140 chromosomes examined in 70 unaffected and unrelated individuals. Information theory mutational analysis shows that the base change lowers the information content of the splice site from 6.0 to -6.8 bits, so that splicing would not be expected to occur at the altered site. CONCLUSIONS: Taken together, these observations suggest that the observed mutation might be causally related to the cataracts in this family.

Familial subepithelial corneal amyloidosis (gelatinous drop-like corneal dystrophy): exclusion of linkage to lactoferrin gene.

PURPOSE: Because corneal tissue with familial subepithelial corneal amyloidosis (FSCA; gelatinous drop-like dystrophy of the cornea) contains lactoferrin the possibility that the FSCA gene was the human lactoferrin (hLF) gene was investigated. Due to contradictory published information we also mapped the hLF gene. METHODS: We mapped the hLF gene using a genomic clone of the entire hLF gene as a probe by fluorescence in situ hybridization (FISH). Utilizing PCR primers that are specific to the hLF gene, we also mapped the hLF via radiation somatic cell hybrid analysis. Linkage of the FSCA gene to the hLF gene was evaluated by genetic linkage analysis using polymorphic markers within and in the vicinity of the hLF gene. RESULTS: The hLF gene mapped to the short arm of chromosome 3 at 3p21. Linkage analysis using polymorphic markers for hLF and haplotype analysis of the 3p21 loci indicates that the FSCA gene is not linked to the 3p21 locus. CONCLUSIONS: The gene for FSCA is not the hLF gene in these families.

Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children.

OBJECTIVE: A retrospective study was undertaken to evaluate long-term anatomic and visual outcomes in eyes of children who underwent bilateral intraocular lens implantation. DESIGN: The study design was a review of medical records of 24 children operated on for bilateral cataracts and posterior chamber-intraocular lenses. PARTICIPANTS: Twenty-four children operated on for bilateral cataracts by 1 surgeon between February 1980 and February 1995 were studied. INTERVENTION: Cataract extraction with bilateral posterior chamber-intraocular lens implantation was performed. MAIN OUTCOME MEASURES: Best-corrected visual acuity, visual acuity without correction, intraocular pressure, manifest refraction, and any intraoperative or postoperative complications were measured. RESULTS: At last follow-up (mean follow-up, 50.8 months; range, 10-149 months), the intraocular lens was in good position and the intraocular pressure was normal without medication in all eyes. Four years after surgery, 79.2% (19 of 24) of first eyes achieved a best-corrected visual acuity of 20/40 or better compared to 66.7% (16 of 24) of second eyes. No eye had any loss in best-corrected visual acuity. In first eyes of 3- to 8-year olds at the time of surgery, 73.3% (11 of 15) achieved a spherical equivalent within 2 diopters of the intended at 4 years after surgery compared to 80% of second eyes. In the 9- to 18-year-old group, 88.9% (8 of 9) of first eyes and 100% of second eyes achieved a spherical equivalent within 2 diopters of the intended at 4 years after surgery. Intraoperative and postoperative complications were minimal. CONCLUSIONS: Long-term anatomic and visual results have been gratifying in this series of patients with bilateral implants.

Silicone oil adhesion to intraocular lenses: an experimental study comparing various biomaterials.

PURPOSE: To perform an in vitro experimental study comparing the degree of adherence of silicone oil to various rigid and foldable intraocular lens (IOL) designs and to the human lens capsule. SETTING: Center for Research on Ocular Therapeutics and Biodevices, Department of Ophthalmology, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA. METHODS: Seven IOL styles comprising various biomaterials were studied: fluorine-treated (Fluorlens), heparin-surface-modified (HSM), hydrogel, Memory-Lens, Poly(methyl methacrylate) (PMMA), soft acrylic, and silicone lenses; the human crystalline lens was also studied. Each lens was immersed in silicone oil for 12 hours, than photographed, studied by scanning electron microscopy (except the crystalline lens), and subjected to computer-generated image analysis to determine the silicone oil coverage. RESULTS: Silicone oil coverage of dry silicone lenses was 100% and of lenses immersed in normal saline, 82.5%. The least coverage was on the heparin-surface-modified lens (mean score 9.4%). Coverage of the other four lenses ranged from approximately 15.1% to 33.7%. Mean coverage of the human lens capsule was 10.9%. CONCLUSION: Although a silicone IOL shows maximal adherence to silicone oil, other lens biomaterials are not immune to this complication. Silicone oil coverage was related to the dispersive energy component of the surface charge of the IOL biomaterial. Low dispersive energy materials had less silicone oil coverage, while those with higher dispersive energy had more oil coverage.

Globe rupture during digital massage after peribulbar anesthesia.

A 75-year-old woman developed globe rupture with extrusion of intraocular contents during digital massage after periocular injection of an anesthetic. The rupture was repaired. At the last follow-up 6 months after surgery, visual acuity was 20/160. The retina was attached, and the vitreous hemorrhage was resolving. This complication of peribulbar anesthesia and digital massage highlights the importance of using quantitative techniques to induce hypotony during peribulbar anesthesia.

Secondary capsule-supported intraocular lens implantation in children.

PURPOSE: To evaluate surgical problems, postoperative complications, and visual results of secondary posterior chamber intraocular lens (IOL) implantation in children. SETTING: L.V. Prasad Eye Institute, Hyderabad, India. METHODS: A retrospective study was done of secondary IOL implantation in 27 children (35 eyes) who were not satisfied with aphakic glasses and were intolerant of or reluctant to use contact lenses. The extent of posterior capsular support was assessed prior to surgery. Additional surgical procedures were posterior synechiolysis (11 eyes), anterior vitrectomy (8 eyes), pupilloplasty (2 eyes), and membranectomy (2 eyes). RESULTS: Postoperative complications included wound leak (1 eye), uveitis (5 eyes), peripheral anterior synechias (2 eyes), and retinal detachment (1 eye). Visual acuity improved or remained at the preoperative level in 34 eyes. CONCLUSION: Secondary posterior chamber IOL implantation is an effective optical modality for managing pediatric aphakia. Observation must continue to determine the long-term safety of the procedure.

Physical and mechanical principles of phacoemulsification and their clinical relevance.

A clear understanding of the physical and mechanical principles that govern phacoemulsification can facilitate usage of this technique for effective and efficient cataract removal in a variety of clinical situations. This article addresses separately, concepts pertaining to the three essential components of phacoemulsification, namely, irrigation, aspiration and emulsification. Machine settings are suggested for the various techniques presently in use. Finally, alternative approaches for lens removal that are currently being investigated are briefly discussed.

Computerized topography of selective versus all-suture release to manage high astigmatism after cataract surgery.

PURPOSE: To compare the efficacy of selective suture release (SSR) with all-suture release (ASR) in controlling corneal astigmatism after cataract surgery. SETTING: Sight Saver's Cornea Training Centre, L.V. Prasad Eye Institute, Hyderabad, India. METHODS: This prospective, randomized study evaluated the effect on astigmatism of two techniques of suture release in 30 patients with more than 3.00 diopters (D) of corneal astigmatism after cataract surgery. All patients had interrupted sutures with well-healed wounds. Fifteen patients had ASR irrespective of the location of the steep meridian. In the other 15, only the suture located in the steep meridian was selectively released. The pattern of decay of astigmatism after suture release was studied using computerized videokeratography. RESULTS: Mean pretreatment corneal cylinder was 6.30 D +/- 2.72 (SD) in the ASR group and 6.95 +/- 1.67 D in the SSR group. In the ASR group, corneal cylinder dropped to 3.70 +/- 1.15 D immediately after suture release and further decreased to 1.82 +/- 0.66 D at 1 week (P < .001). In the SSR group, astigmatism swung erratically to the adjoining sutures and decreased unpredictably at an average of 1.32 +/- 2.00 D with each suture release. CONCLUSION: The ASR technique was more predictable and less cumbersome than the SSR method.

Experience during the learning curve of laser in situ keratomileusis.

PURPOSE: To identify pitfalls and offer hints on achieving a successful outcome during the early laser in situ keratomileusis (LASIK) learning process. SETTING: Gimbel Eye Centre, Calgary, Alberta, Canada. METHODS: This was a retrospective review of the preoperative planning, surgical procedure, intraoperative and postoperative problems, and early postoperative anatomic and refractive results in the first 73 eyes that had LASIK. RESULTS: Intraoperative complications included failure of the keratome to make a cut, excessively thin cap, repositioning difficulty, and inadequate intraocular pressure elevation. Early postoperative complications included excessive central and peripheral wrinkling of the cap, peripheral lipid deposits, and central edema of the cap. One month postoperatively, mean spherical equivalent refraction was -0.90 diopters (D) (range +1.75 to -6.00 D), and 45 eyes had a best corrected visual acuity between 20/15 and 20/40. CONCLUSION: Our retrospective review of the problems experienced during the early LASIK learning process should help novice lamellar refractive surgeons avoid such problems and shorten the learning curve.