Suction cup/contact lens complications following penetrating keratoplasty.

PURPOSE: Rigid gas permeable (RGP) contact lenses facilitate visual rehabilitation in cases of high or irregular corneal astigmatism following penetrating keratoplasty. A variety of plunger-like suction cup devices are available to assist in the removal of these lenses. METHODS: We report three patients with serious complications associated with the use of a suction cup device for contact lens removal following penetrating keratoplasty. RESULTS: Two patients suffered corneal wound dehiscence following contact lens removal; one contact lens was removed by the patient's spouse and the other was removed by a trained technician. A third patient triggered a graft rejection, and ultimately, graft failure, after a vigorous attempt at lens removal. CONCLUSIONS: Forces generated by suction cup devices during removal of RGP contact lenses are sufficient to cause significant trauma. Contact lenses with an apical clearance fit may augment these forces, with the potential for complications following penetrating keratoplasty.

Filtration surgery in rabbits treated with diclofenac or prednisolone acetate.

We performed filtration surgery in one eye of each of 28 rabbits. Either a nonsteroid (diclofenac) or a steroid (prednisolone acetate) was given as a postoperative antiinflammatory agent. On no examination day was there a significant difference in the intraocular pressure of the rabbits that had received diclofenac as contrasted with those that had received prednisolone acetate (P > .05, Student's t-test). Neither was there, based on log-rank life-table analysis, any significant difference between the two groups in terms of filtering bleb survival (P = .484). Finally, there were no significant differences on any examination day between the two groups in terms of bleb height or conjunctival injection (P > .05, Mann-Whitney U-test). We conclude that in this rabbit model for filtration surgery, the postoperative antiinflammatory effect of diclofenac was similar to that of prednisolone acetate. Because a nonsteroidal agent such as diclofenac that could provide an antiinflammatory effect sufficient to allow optimal bleb survival in humans, without the level of potential side effects of corticosteroids, might be clinically useful, further studies may be warranted.

Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique.

A modification of the original Miyake technique of posterior photography of human eyes obtained postmortem is presented. A detailed description of globe preparation and equipment is described. Use of modern technology including a high magnification microscope system and video camera permits dynamic or realtime observations of tissue effects of various surgical procedures such as the cataract operation. This technique provides both a research and educational tool that can be used by ophthalmologists to improve the quality of surgery. Most important, it is an instructional tool that should reduce the "learning curve" that is inherent when modifying one's surgical technique.

Protective effect of the anterior lens capsule during extracapsular cataract extraction. Part I. Experimental animal study.

In an experimental study using albino Rex rabbits, the intercapsular cataract extraction (ICCE) technique was performed in 20 eyes with a small anterior capsulotomy. A large, can opener capsulotomy was performed in another 20 eyes, and 10 unoperated eyes served as controls. Endothelial cell loss was determined by vital staining with Trypan blue and Alizarin red S stains. Average endothelial cell loss with the ICCE technique was 1.2%; with the can opener technique, the average cell loss was 6.6%. This difference was statistically significant (P less than 0.01). The percentage of endothelial cell loss in the control eyes was 0.5. A positive correlation between endothelial cell loss related to phacoemulsification time and/or the amount of irrigating fluid used existed for the can opener group only (P less than 0.01). These results demonstrate that the presence of an almost intact anterior lens capsule during removal of lens substance is protective to the corneal endothelium.

Protective effect of the anterior lens capsule during extracapsular cataract extraction. Part II. Preliminary results of clinical study.

In a clinical study, 61 patients underwent phacoemulsification with subsequent intraocular lens (IOL) implantation. An intercapsular capsulotomy with phacoemulsification was performed on 23 patients and a can opener capsulotomy with phacoemulsification on 38 patients. Wide-field specular microscopy was performed preoperatively and postoperatively on all of the eyes in the study. The cell counts were not divulged to the surgeon before or at the time of surgery. Average endothelial cell loss for the intercapsular technique was 3.9%; with the can opener technique, the average cell loss was 10.1%. This difference was statistically significant (P less than 0.01). Positive correlations between endothelial cell loss relating to ultrasound time and/or the hardness of the cataract existed for the can opener group only (P less than 0.01). These results demonstrate that a protective effect is provided by the presence of the anterior lens capsule during lens substance removal.

[Protective effect of the anterior lens capsule: corneal endothelial cell loss following intercapsular phacoemulsification compared with phacoemulsification with large open capsulotomy]. / Protektiver Effekt der vorderen Linsenkapsel: Corneaendothelzellverlust nach interkapsulärer Phakoemulsifikation verglichen mit Phakoemulsifikation mit grosser offener Kapsulotomie.

In an experimental study using rabbits, the intercapsular technique was performed in 20 eyes to make a small anterior capsulotomy. A large, "can opener" capsulotomy was performed in 20 eyes, and ten eyes (five non-operated animals) served as controls. Endothelial cell loss was determined by vital staining with Trypan blue and Alizarin red S. Average endothelial cell loss with the intercapsular technique was 1.2%; with the can opener technique the cell loss was 6.6%. This difference was statistically significant (p less than 0.01). The percentage in the control eyes was 0.05%. Positive relations between endothelial cell loss related to phacoemulsification time and/or the amount of irrigating fluid used existed for the can opener group only (p less than 0.01). These results demonstrate that the presence of an almost intact anterior lens capsule during removal of lens substance is protective to the corneal endothelium.

Posterior capsular opacification and intraocular lens decentration. Part I: Comparison of various posterior chamber lens designs implanted in the rabbit model.

Experimental phacoemulsification procedures were performed in 54 Rex rabbits. In 96 eyes, posterior chamber intraocular lenses (IOLs) were implanted in the capsular sac, and 12 eyes served as controls with no lens implantation. The IOLs were divided into eight groups consisting of both one-piece and three-piece styles with various optic designs. Each lens was evaluated for the relative effect on posterior capsular opacification (PCO) and optic decentration, two of the most common complications of modern cataract surgery and IOL implantation. Optics with a convex-anterior, plano-posterior design (the type of IOL optic most frequently implanted today) had the highest incidence of PCO. With capsular fixated IOLs, the features that have a statistically significant impact on reducing PCO include (1) one-piece, all-polymethylmethacrylate (PMMA) IOL styles, (2) a biconvex or posterior convex optic design, and (3) angulated loops. Lens decentration was not affected by the optic design, but statistical analysis showed that one-piece, all-PMMA IOL construction provided the most consistent centration.

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.

Comparative histopathologic study of various lens biomaterials in primates after Nd:YAG laser treatment.

A Nd:YAG laser was used to perform posterior capsulotomies on primates in whom one-piece silicone or three-piece polymethylmethacrylate intraocular lenses were in place for more than one year. The eyes were followed for eight weeks after treatment before enucleation. Histologically, no toxic effects caused by the dispersion of any of the biomaterial within the eyes and no significant inflammatory reactions were seen. The silicone lenses used in this study compared favorably with traditional polymethylmethacrylate lenses when posterior capsulotomies with a Nd:YAG laser were performed.