Refractive keratoplasty with intrastromal hydrogel lenticular implants.

The feasibility of using hydrogel lenticular implants of high water content to alter the anterior corneal curvature for purposes of refractive keratoplasty has been investigated in rabbits. Lenticules (6 mm in diameter) of Permalens (Perfilcon-A) were trephined from contact lens and implanted within an intralamellar pocket in the cornea. The in vitro glucose flux across the hydrogel (0.23 mm thick) was measured at 131 +/- 7 micrograms/cm(2)/hr. For clinical comparison, non-water-permeable disks of Teflon were also implanted. The Teflon implant caused an aseptic ulcer to develop anterior and central to the implant by 9 +/- 4 days. The hydrogel lenticular implant did not cause central ulceration during the 7 month postoperative follow-up. There was a thinning and eventual erosion of the stroma anterior to the edge of the hydrogel implant, 16 +/- 7 weeks. The glycogen contents of the epithelium anterior to (1) the sham operation, i.e., lamellar pocket dissection, (2) the implanted hydrogel lenticule with or without the presence of an erosion, and (3) the control corneas were statistically from the same population. Yet there was a slight dehydration of the stroma anterior to the hydrogel implant when compared to control tissue. A thin-edged implant lenticule design should overcome the stromal thinning caused by the thick-edge implants. During the short-term follow-up, the hydrogel lenticular implant proved to be successful as a refractive keratoplasty implant material.

Instruments and techniques for anterior chamber implants.

The widely used white-to-white + 1 method was investigated clinically for its accuracy in choosing implant length. This method allowed the surgeon to open one implant per case in approximately 65% of cases. The basic concept of adding 1 mm to the clear corneal diameter was then investigated with cadaver eyes. The concept was found to be quite inaccurate. An anterior chamber ruler is described that allows the surgeon to open one implant per case in 95% of cases. An implant ruler for checking the length of the implant and the plane of the feet also is described. An implant positioner is described that inserts the distal feet, inserts the proximal feet, checks the implant fit, and changes the axis if necessary.

Effects of extracapsular implant techniques on endothelial density.

A comparison of surgical techniques with phacoemulsification showed that changing from anterior to posterior chamber emulsification afforded a drop in endothelial cell loss from 24.6% to 12.5%. Implantation of a Shearing posterior chamber lens instead of a Binkhorst two-loop iridocapsular lens did not decrease the cell loss using anterior chamber emulsification. Cell loss was approximately 25% in both groups. The addition of sodium hyaluronate (Healon) to the procedure of posterior chamber emulsification and implantation of a Shearing lens did not raise or lower the cell loss noted when using air alone. However, with the technique described whereby most of the sodium hyaluronate is irrigated from the eye at the end of the procedure, there was no increase in intraocular pressure postoperatively and no untoward effects. Posterior chamber emulsification seems mandatory, and though sodium hyaluronate did not improve cell loss, its use as a precaution seems to be completely safe when correct procedures are followed.

Corneal trauma in intracapsular and extracapsular cataract extraction with lens implantation.

We examined the central corneal endothelium before and eight weeks after cataract extraction and lens implantation in 99 consecutive intracapsular and extracapsular extractions each. There was no statistically significant different between the mean endothelial cell loss of 17.1% in the intracapsular group and 13.6% in the extracapsular group. The variation in individual endothelial cell sizes was less postoperatively in the extracapsular extractions. The central corneal thickness were the same in the two groups. There was no statistically significant difference between the mean endothelial cell loss of 17.0% in 24 posterior chamber lenses and 12.1% in 69 transiridectomy clip lenses, both with extracapsular cataract extraction. When combined with intraocular lens implantation, extracapsular cataract extraction, even when performed by surgeons inexperienced with extracapsular techniques, caused no greater corneal endothelial damage than intracapsular extraction.

Treatment of dislocated posterior chamber intraocular lenses.

We treated five patients with posterior chamber intraocular lenses that were dislocated into the vitreous cavity. Using a pars plana approach, a vitrectomy was performed, and the intraocular lens was grasped with forceps and repositioned behind the iris with the lens loops in the ciliary sulcus. The loops were sutured to the iris in four cases. Visual acuity returned to 20/25, or better, in each case.

Polyvinyl alcohol as a protective coating on intraocular lenses.

Sixty-eight intraocular lenses were implanted in cats to compare the efficacy of a new polyvinyl alcohol coating in protecting the corneal endothelium from lens-cell contact damage. The mean endothelial density after implantation of the coated lens was significantly higher than the cell density in those eyes receiving the uncoated lens. We saw no clinical signs of unusual inflammation; whole-eye histopathologic study disclosed no signs of inflammation or toxicity related to the coating. Ten coated lenses were placed in balanced salt solution or perfused with balanced salt solution at 0.5 mL/min. The coating remained intact for 60 minutes, affording corneal endothelial protection for this period. In a rabbit anterior chamber toxicity study, using balanced salt solution as a control, no differencs in reaction in the anterior chamber or intraocular pressure were noted.

Complications of intraocular lenses. A historical and histopathological review.

Recent improvements in intraocular lens (IOL) design, manufacturing techniques, and surgical techniques have greatly reduced the incidence of complications following implantation, and many authors now consider IOL implantation to be among the most safe and effective major surgical procedures. However, adverse reactions are still seen--some as late sequelae of earlier IOL designs and implantation techniques and some as sequelae of more recent implantations using "state-of-the-art" lenses and surgical techniques. Complications may be due to various factors, including surgical technique, IOL design, or the inability of some eyes with preexisting disease to tolerate an implant. The authors trace the evolution of IOLs since Ridley's first implant, summarizing the modifications in lenses and surgical techniques that were made as complications were recognized. They then review the clinical and histopathological features of selected cases from more than 200 IOLs and/or globes removed due to IOL-related complications and studied in the University of Utah Ocular Pathology Laboratory. It is hoped that this review will provide insights into the pathogenesis of IOL complications, enhancing the current success of implant procedures and stimulating further basic and clinical research in this area.

Director for the Choyce implant.

I designed an instrument for directing the inferior and superior feet of the Choyce intraocular implant into the anterior chamber angle.

Pathologic examination of a J-loop posterior chamber intraocular lens in the ciliary sulcus.

A Shearing J-loop posterior chamber intraocular lens was implanted into an eye after an extracapsular cataract extraction. The loops were deliberately placed in the ciliary sulcus between the iris root and the ciliary processes. The patient died 11 months after surgery and the eye was obtained for pathologic study. The complete lack of inflammation in the uveal tissue where the loops of the intraocular lens had rested confirmed the benign postoperative course of this eye.

Posterior chamber intraocular lens insertion during pars plana lensectomy and vitrectomy for complications of proliferative diabetic retinopathy.

We inserted posterior chamber lenses into 21 eyes with complications of diabetic retinopathy upon completion of pars plana lensectomy and vitrectomy in a single session. After the original surgery, two eyes developed retinal detachments and underwent vitrectomy revisions with scleral buckling, one eye had a fluid-gas exchange for residual vitreous cavity blood, one eye had supplemental laser treatment, and one eye had intraocular antibiotics for endophthalmitis. Six months later, postoperative vision was better in 16 of the 21 eyes (76%), the same in four eyes (19%), and worse in one eye (5%). In 16 eyes visual acuity was 20/200 or better, and in six eyes it was 20/40 or better postoperatively. Decreased vision was caused by preexisting macular disease; two eyes had corneal edema with iris neovascularization associated with residual retinal detachment. The procedure and lenses were well tolerated and provided good pseudophakic vision.

Measurement of intraocular lens decentration and tilt in vivo.

A method for measuring the tilt and decentration of intraocular lenses (IOLs) in the static eye using the Purkinje image locations is presented. The patient fixates on a target that is coaxial with the camera or is at a predetermined angle with the camera axis. A telecentric stop is introduced in the camera so the positions of the Purkinje images on the film are independent of their distance from the camera. Measurements of the image locations on the film are used with anterior chamber depth and corneal curvature measurement to calculate the tilt and decentration of the IOL. In a group of 14 randomly selected patients with posterior chamber IOLs, 13 gave Purkinje images that could be measured. The average tilt was 7.8 degrees and the average decentration was 0.7 mm.

Posterior capsular opacification and intraocular lens decentration. Part II: Experimental findings on a prototype circular intraocular lens design.

In a prospective randomized study, 25 New Zealand white rabbit eyes were implanted with four intraocular lens (IOL) designs. These included a one-piece modified J-loop IOL, a three-piece modified J-loop IOL, a rigid disc IOL, and an experimental compressible disc (CD) IOL. The CD IOL revealed the lowest mean posterior capsular opacification (PCO) of all IOLs tested (P less than .01). With all lenses tested, a positive correlation between PCO and decentration was found (R = 0.55, P less than .05). These results suggest that because of its design features (i.e., one-piece construction, biconvex optic, posterior angulation of the fixation element), the CD lens produces a mechanical barrier against lens epithelial cell migration and reduces the incidence of PCO.

Keratorefractive aspects of the scleral pocket incision and closure method for cataract surgery.

All current cataract incisions induce transient and permanent changes in corneal astigmatism. Typically, a two-phase astigmatic response is observed; an initial with-the-rule change is followed by an eventual and permanent against-the-rule shift from preoperative astigmatism. The earlier literature suggests that the magnitude of the net astigmatic swing approximates 6.0 diopters for large limbal wounds closed with interrupted sutures. However, applying the tenets of keratorefractive surgery to the cataract incision and its closure allows the surgeon to limit postoperative iatrogenic astigmatic swings. The reduced phacoemulsification incision size in combination with a scleral pocket closed with a continuous single knotted 10-0 monofilament nylon suture under tonometric and keratometric control significantly dampens the changes in corneal astigmatism during the early and late postoperative periods. My published reports, as evaluated in the present study, reveal that the net astigmatic swing may be reduced to less than 1.5 diopters, thereby affording rapid and stable optical results.

Pseudophakic bullous keratopathy. A clinical-pathologic analysis.

Of 226 patients who had an intraocular lens implanted over a three year period, 6.2% developed bullous keratopathy compared with 2.2% of 90 patients who had a standard cataract extraction performed by the same surgeon. An additional 4.0% of the lens implant patients developed peripheral or intermittent corneal edema. The factors related to the higher incidence of this complication in lens implant patients included corneal touch during implantation, prolonged postoperative iritis and, in cases of mild or peripheral corneal edema without bullous keratopathy, recurrent lens dislocation. The most consistent pathologic findings in 10 corneas that required keratoplasty were epithelial edema and loss of corneal endothelium. Means to prevent this complication are discussed.

Removal of intraocular lenses.

The following points should be considered regarding removal of an IOL: 1. Be sure that it is an offending agent and not an innocent bystander before deciding to remove it. 2. An offending IOL may usually be replaced with an anterior chamber lens, with excellent results. 3. Removal of an IOL is usually a difficult procedure in less-than-satisfactory circumstances, and should be undertaken only by an experienced implant surgeon, with special attention to the delicate nature of the patient's eye and emotional feelings about this dilemma. 4. Every effort should be made to perform maneuvers in a closed system with minimal opening and folding of the cornea and minimal irrigation of the anterior chamber. 5. An offending IOL should be removed and replaced with an appropriate lens before irreversible damage has been done to the eye, if at all possible.

Secondary implantation.

Aphakia is a disabling condition. It must be corrected by spectacles, contact lenses, refractive keratoplasty, or insertion of a pseudophakos. In those patients who do not tolerate a contact lens or cataract spectacles, refractive keratoplasty or secondary implantation of an IOL should be considered. Keratophakia and hyperopic keratomileusis have not yet evolved to the point at which refractive keratoplasty can be considered a practical answer to aphakia. This leaves a significant population of aphakic patients who can be visually rehabilitated only be secondary implantation of an IOL. Despite the risks and hazards associated with any intraocular surgery, the benefits derived from successful correction of aphakia with secondary implantation fully justify this procedure. Secondary implantation is a proved, successful modality for the corretion of aphakia. The number of patients requiring secondary implantation is not great, but in patients in whom secondary implantation is indicated, both the patient and the physician will find the results most rewarding.

The Ridley posterior chamber lens.

In summary, if used in the way I recommend, the Copeland lens gives excellent visual results and freedom from irritation. These results are sufficiently good that they need not be compared with the results of cataract surgery without implantation of a pseudophakos. It can be pointed out that these cases were all chosen with the idea of having a successful result. One cannot pick and choose all cataract patients in this way, but one can choose patients for lens implantation in this manner and thereby ensure excellent results.

Prevention and management of corneal decompensation.

While the chances of corneal decompensation following lens implantation are low, they are greater than in nonimplant cataract surgery and increase with the passage of time postoperatively. All the factors leading to corneal decompensation are not known, but available evidence suggests the most significant is trauma at the time of surgery. The likelihood of corneal decompensation can be limited by careful patient selection and surgical techniques and by appropriate management of postoperative complications. In the event of irreversible corneal decompensation, penetrating keratoplasty, with or without removal of the implant lens, offers a substantial chance of visual rehabilitation.

Experience with extracapsular extraction and binkhorst 2-loop intraocular lenses: preliminary communication.

Extracapsular cataract extraction and implantation of a Binkhorst 2-loop intraocular lens were performed on 50 patients. The majority of the patients achieved a corrected postoperative acuity of 6/9. Operative, immediate postoperative and late postoperative complications are discussed. The commonest postoperative complication was the formation of a dense capsular membrane which required capsulotomy in 9 patients. Suggestions are put forward for improving the result of this rewarding operation.

[Implantation of intraocular lens in keratoplasty with cataract extraction (author's transl)]. / L'implantation d'une lentille intra-oculaire au cours de l'intervention combinée kératoplastie et cataracte.

A combined operation a) keratoplasty; b) cataract extraction; c) iridocapsular implant must be advised when a corneal opacity and a cataract require both a surgical treatment. Six months after surgery, functional results are good in 4 cases/5.