The triple procedure; combined penetrating keratoplasty, cataract extraction and lens implantation

Femtosecond laser-assisted keratoplasty: full and partial-thickness cut wound strength and endothelial cell loss across a variety of wound patterns

PURPOSE

To evaluate wound strength for patient safety during transport and endothelial viability when partial and complete femtosecond laser-assisted keratoplasty (FLAK) incisions are made in cadaveric corneas.

METHODS

19 human corneoscleral rims were divided into six groups, mounted on an anterior chamber maintainer and cut with a femtosecond laser programmed to the following patterns: 'zigzag' (A), 'mushroom' (B) and 'top hat' (C) in both full (1) and partial (2) thicknesses. The pressure required to produce leakage from the corneal incision was then measured. Eight additional corneas were cut with the 'zigzag' pattern: four full and four partial thickness, prepared and transported per standard eye bank protocol, and analysed for endothelial cell loss with trypan blue staining and digital image analysis.

RESULTS

Mean leakage pressure in mm Hg for group A1 was 110 (SD 94); group A2, 1180 (SD 468); group B1, 978 (SD 445); group B2, 987 (SD 576); group C1, 710 (SD 474); group C2, 1290 (SD 231). There was a significant difference in leakage pressure between groups A1 and A2 (p=0.05), groups A1 and B1 (p=0.05), and groups A1 and C1 (p=0.05). Mean percentage endothelial damage after full-thickness cuts was 8.40 (SD 2.34) and 5.30 (SD 1.33) in partial-thickness cuts (p=0.11).

CONCLUSIONS

Partial thickness zigzag, top hat and mushroom-style partial FLAK incisions left an intact tissue wall with high resistance to rupture, whereas full-thickness cuts were more variable. Laser trephination and eye bank handling protocol for donor FLAK buttons leads to moderate peripheral endothelial cell loss in tissue with both complete and partial cuts.

Risk factors for failure of simultaneous penetrating keratoplasty and cataract extraction

OBJECTIVE

To evaluate the indications, complications, and outcomes of simultaneous cataract extraction and penetrating keratoplasty (PKP) and the risk factors for failure of the procedure.

SETTING

Tertiary referral medical center.

METHODS

In a retrospective noncomparative interventional case series, the charts of 66 consecutive patients (70 eyes) who had simultaneous PKP and cataract extraction using the same surgical technique were reviewed.

RESULTS

The mean follow-up was 32.4 months (range 6 to 125 months). The primary corneal graft remained clear in 48 eyes (69%) and failed in 22 eyes (31%). Sixteen eyes with a failed graft (73%) had 1 or 2 repeat keratoplasties; 8 (50%) were successful. At the end of follow-up, 56 eyes (80%) had a clear corneal graft. Nine eyes (41%) with a failed primary graft and 2 eyes (4%) with a clear primary graft had intracapsular cataract extraction (P<.001); 13 eyes (59%) and 46 eyes (96%), respectively, had extracapsular cataract extraction (P<.001). All eyes with a failed primary graft and 18 eyes (37%) with a clear primary graft had postoperative complications (P<.001). Eyes with a failed graft had more postoperative surgical interventions (P<.001). There were no statistical differences between eyes with clear grafts and eyes with failed grafts in sex, age, indications for surgery, corneal graft diameter, intraoperative vitreous loss, and intraocular lens placement.

CONCLUSIONS

Intracapsular cataract extraction, postoperative complications, and postoperative surgical interventions may increase the risk for graft failure in simultaneous cataract extraction and PKP. Intraocular lens implantation did not increase the risk for graft failure.

Evaluation of intraocular lens power calculation formulas in the triple procedure

PURPOSE

To determine whether the choice of intraocular lens (IOL) power formula improves IOL power predictions and whether personalized constants within the IOL power formula are critical factors in improving refractive predictions after combined penetrating keratoplasty, cataract extraction, and IOL implantation.

METHODS

Records of 46 patients who had the triple procedure between January 1988 and December 1992 were evaluated using the SRK II, SRK/T, Holladay, and Hoffer Q formulas to predict the postoperative spherical equivalent refractions for implanted lens power. Calculations were carried out with and without the use of personalized constants. The predictive accuracy of each formula was assessed by comparing the actual postoperative spherical equivalent refractive error with that predicted by the formulas. The predictive error and the distribution of predictive errors were used to assess predictive accuracy.

RESULTS

There was no difference in the mean absolute predictive errors and the distribution of predictive errors for the four formulas evaluated (P > .05). The use of personalized formula constants significantly reduced the mean absolute predictive error for the SRK II, SRK/T, and Holladay formulas (P < .05) and approached significance for the Hoffer Q formula.

CONCLUSION

The findings suggest that the choice of IOL power formula does not affect IOL power predictions in the corneal triple procedure; however, personalized constants within a formula appears to be a critical factor in improving postoperative refractive predictions.

Simultaneous penetrating keratoplasty, extracapsular cataract extraction, and intraocular lens implantation

The postoperative results of 210 consecutive eyes in 177 patients who had simultaneous penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber intraocular lens (IOL) implantation (triple procedure) were reviewed. All procedures were performed by one surgeon between January 1980 and December 1989. The most common diagnosis requiring a triple procedure was Fuchs' endothelial dystrophy. The remainder of the patients required the procedure for either corneal scarring, keratoconus, or Chandler's syndrome. Of the 210 grafts, 191 (91%) remained clear with a mean follow-up of 53 months (range 6 to 116 months). The mean preoperative keratometry (K) reading (n = 161) was 44.51/44.85 (SD 4.86/4.94), and the mean postoperative K reading (n = 111) was 44.29/43.50 (SD 3.83/3.63). The mean IOL power (n = 196) was + 20.87 diopters (D) (SD 2.86). The mean postoperative best visual acuity (n = 166) was 20/65 with a range from 20/20 to less than 20/400, although 61% had 20/50 acuity or better and 92% had 20/100 acuity or better. The mean spherical correction in 155 eyes was - 1.38 (SD 2.89), and the mean positive refractive cylinder was + 3.21 (SD 2.20). One hundred forty six of the 155 eyes with reported refractions (96%) had 6 D or less of refractive cylinder. Correlation of the recipient-donor disparity % and refractive cylinder was significant such that as disparity increased refractive cylinder increased (r = 0.197, P = .021). Correlation of the recipient-donor disparity % and keratometric cylinder indicated a similar trend but was not significant (r = 0.105, P = .310).

Assessment of success and complications of triple procedure surgery

In an effort to quantify both the success and complications of triple procedure surgery, we studied a consecutive series of 166 patients who underwent this procedure. The average length of follow-up was 17 months. Of 166 patients, 138 (83%) achieved a visual acuity of 20/40 or better after surgery; in the most recent 52 patients, 26 (50%) achieved this within two months. The most frequent complications during the postoperative period were glaucoma (40 patients, 24%), endothelial graft rejection episodes (two-year cumulative risk, 16%), and astigmatism (mean keratometric cylinder, 4.97 D). Additional surgical interventions were required in 27 patients (16%).

Penetrating keratoplasty and cataract surgery: the advantages of an extracapsular technique combined with posterior chamber intraocular implantation

The results of 28 consecutive triple procedures and 33 cases of combined penetrating keratoplasty and extracapsular extraction are presented. All the eyes with the triple procedure maintained a clear graft; 77 per cent achieved an acuity of 6/12 or better. The average time before a refractive correction could be dispensed was 8.2 months, while after a combined procedure the interval was 17.4 months, although in both groups the average time until the best visual acuity was reached was similar.

The triple procedure. Analysis of outcome, refraction, and intraocular lens power calculation

Presented are the results of 66 consecutive, elective, combined procedures of penetrating keratoplasty, extracapsular cataract extraction, and intraocular lens insertion (triple procedure) performed by three surgeons between January 1981 and January 1984. After a mean postoperative followup of 15.8 months, over 90% of the eyes had clear grafts, and of the 56 eyes with good preoperative visual potential, 77% achieved a best corrected visual acuity of 20/40 or better. The postoperative mean refractive deviation from emmetropia was 2.17 diopters, with a range of +6.62 D to -5.50 D, 62% falling between -2.00 and +2.00 diopters. Using multiple regression analysis of preoperative and postoperative variables, an attempt was made to derive a predictive formula for the power of the intraocular lens to be implanted during the triple procedure. In contrast to cataract surgery, where axial length and corneal power remain fairly constant preoperatively and postoperatively, penetrating keratoplasty produces marked changes in corneal curvature and power. Therefore, a single formula could not be derived to predict accurately the intraocular lens power for the patients. However, using the results for an individual surgeon, a formula was derived that could improve the predictability of intraocular lens power.

Intraocular lens powers used in the triple procedure. Effect on visual acuity and refractive error

The refractive results of 43 consecutive triple procedures (transplant, cataract extraction, and lens implant) performed by one surgeon were analyzed. Twenty-one out of 43 eyes achieved refractive errors within 2 diopters (D) of emmetropia. The mean refractive error was -1.79 D, and the mean corneal astigmatic error was 2.75 D. Seventy percent of the eyes achieved 20/40 or better corrected acuity. Forty-four percent had 20/80 or better uncorrected acuity. Using the average postoperative keratometry readings from other recent transplant cases and an updated A constant in the SRK regression formula would have placed 39 of 43 eyes (91%) within 2 D of emmetropia with a mean refractive error of -0.07 D. The use of recent keratometry readings in a multiple regression formula is recommended to improve refractive results with the triple procedure.

Intraocular lens calculation in combined penetrating keratoplasty, cataract extraction and intraocular lens implantation

We retrospectively studied 53 consecutive triple procedures (combined penetrating keratoplasty, cataract extraction and intraocular lens implantation) performed at the Bascom Palmer Eye Institute from January 1980 through August 1983. Most patients had at rest six months of follow-up. The final postoperative refractive error was compared to the predicted refractive error using the preoperative axial length and the estimated keratometry readings. The deviation from the predicted refractive error was correlated with the source of preoperative keratometry readings, the degree of donor oversize, and the donor age. We found that using keratometry readings from the operated eye resulted in more accurate intraocular lens calculations than using estimated keratometry readings not obtained from either eye (P less than .05).

Secondary intraocular lens implantation during or after corneal transplantation

An analysis of the effects of secondary intraocular lens implantation on the clinical results of corneal transplantation in four groups of eyes showed that the mean visual acuity in 27 eyes undergoing intraocular lens implant at the time of aphakic keratoplasty and in 12 eyes undergoing intraocular lens implantation after corneal transplant was approximately 20/40; the visual acuity in 24 eyes undergoing intraocular lens exchange at the time of transplant for pseudophakic bullous keratopathy and in 18 eyes undergoing intraocular lens removal at the time of transplant for pseudophakic bullous keratopathy was poorer. The techniques used were simple and did not increase the incidence of transplant complications. Intraocular lens implantation combined with corneal transplants should be considered in aphakic eyes requiring corneal transplants, in eyes requiring simultaneous cataract extraction and corneal transplants, and in eyes in which cataracts have developed after corneal transplant.

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.

The triple procedure: combined penetrating keratoplasty, extracapsular cataract extraction and lens implantation. An expanded experience

The results of 177 triple procedures are presented from a continuous series of 197 cases recorded from 1973 to 1982. Eighty-nine percent achieved a visual acuity of 20/40 or better within a minimum followup period of six months. The complication rate was low, and usually managed medically. Subsequent major surgical procedures were required in only twelve (7%) of these cases (eight repeat keratoplasty, two retina repair, one resuture of graft incision, and one peripheral iridectomy). Subsequent minor surgical procedures were for discission of the posterior lens capsule in 50% of the medallion-style lens cases, and in 7% of the posterior chamber lens cases.

Combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber lens implantation

A retrospective chart review of 18 consecutive unselected cases of combined penetrating keratoplasty, extracapsular cataract extraction, and posterior chamber lens implantation was performed. Overall, 89% of the grafts remained clear with follow-up between six and 54 months (average 21 months). Visual acuities were 20/50 or better in 61% of the cases and 20/80 or better in 83%. Postoperative complications included two graft failures, two cases of secondary glaucoma, one case of cystoid macular edema, and one case of pupil capture. No patients to date have required a secondary discission.