N. S. C. Rice

The success of penetrating keratoplasty for keratoconus

We report the results, over a 20 year period up to 1989, of 201 penetrating keratoplasties in 198 eyes of 158 patients. The five year graft survival was 97%. A corrected visual acuity of 6/12 or better was attained by 91%. The mean spherical equivalent refraction on removal of sutures was -2.68 Ds and the mean cylindrical correction was —5.56 Ds. The cumulative time to dispensing final refractive correction was 38 months for 90% of patients. Rejection episodes occurred in 20% of grafts and were associated with loosening of sutures and bilateral grafts. Atopic patients (28%) were not at greater risk from rejection.Graft refractive surgery was undertaken in 18% and, of these, 55% achieved 6/12 vision or better with an refractive correction which could be dispensed and tolerated within 6 months.

Granular Corneal Dystrophy: Visual Results and Pattern of Recurrence after Lamellar or Penetrating Keratoplasty

BACKGROUND Granular corneal dystrophy is a rare indication for corneal transplantation. Both penetrating and lamellar keratoplasty have been recommended, but because granular corneal dystrophy is known to recur within the donor material and multiple grafts may be necessary, the best surgical option has not been clearly established. The cellular cause of the dystrophy is unknown and the authors hypothesized that the rate and pattern of recurrence within lamellar and penetrating grafts might give clues to its etiology. METHODS The authors compared the visual outcome, rate, and pattern of recurrence after 20 penetrating keratoplasties and 11 lamellar keratoplasties for granular corneal dystrophy. RESULTS Penetrating keratoplasty and lamellar keratoplasty have a good visual outcome in granular corneal dystrophy. Visual acuities after both procedures were not statistically different. Recurrence of the dystrophy within the graft material was almost universal within 4 years. It first appeared centrally and superficially, occasionally adopting a vortex pattern suggesting epithelial involvement. The recurrence-free interval was independent of size and type of graft performed. CONCLUSION The authors recommend lamellar keratoplasty as a primary procedure in managing visually disabling granular corneal dystrophy if the deposits are limited to the superficial cornea. This is particularly applicable in younger patients in whom multiple procedures may be necessary over a lifetime due to recurrence of the dystrophy, and the lower morbidity rate associated with lamellar keratoplasty becomes appreciable. Although granular corneal dystrophy generally is classified as a stromal dystrophy, the pattern of recurrence is more consistent with an epithelial or tear-borne abnormality than a disease of the stromal keratocyte.

The use of silicone drainage tubing to control post-keratoplasty glaucoma

A series of 20 patients who developed severe post-keratoplasty glaucoma unresponsive to medical therapy and trabeculecetomy were treated using silicone drainage tubing and an anterior encircling gutter. The results indicate a four year probability of maintaining vision and normal intraocular pressure (<21 mmHg) of 0.68. In contrast, an earlier series of 13 patients receiving cycloablation with cryotherapy did significantly worse.

Refractive Surgery for Graft-induced Astigmatism after Penetrating Keratoplasty for Keratoconus

Of a series of 201 corneal transplants for keratoconus over a 20-year period, 42 grafts (39 eyes of 38 patients) required further surgery because of intolerable astigmatism (range, -3 diopters [D] to -18 D; mean, 8.9 D). Relaxing incisions, compressive resuturing, and augmented relaxing incisions were the techniques used. All procedures resulted in a similar mean reduction in cylinder -3.6 to 5 D, but the outcome with augmented relaxing incisions was less predictable. Six grafts required two or more procedures for a satisfactory outcome. All patients had corrected visual acuity of 20/30 or better after surgery, and 75% had visual acuity of 20/20 or better. The cumulative time until 90% of the grafts had useful vision was 32 months after refractive surgery. Relaxing incisions offer the prospect of more rapid visual rehabilitation than compressive resuturing.

Microbial keratitis after penetrating keratoplasty

Thirty cases of microbial keratitis after penetrating keratoplasty were reviewed to examine the associated risk factors, the spectrum of pathogens and the prognosis for graft survival and visual outcome.The indications for keratoplasty in this group differed markedly from those for all corneal grafts performed with a much higher incidence of previous microbial keratitis and of herpes simplex keratitis.A positive culture was obtained in 93% of cases and in contrast to microbial keratitis overall, Gram positive organisms predominated particularly streptococcus pneumoniae and staphlycoccus aureus.Risk factors identified were loose or broken sutures, graft decompensation and a poor ocular surface environment.There was a poor prognosis for graft survival with only 23% of cases retaining a clear graft. Overall 53% of cases were regrafted.

Longterm prognosis for corneal grafting in herpes simplex keratitis

A previously reported cohort of patients4 was reviewed after mean follow-up of 10.9 years. The overall probability of survival was 45%, but first grafts had a greater probability of survival than second (P= 0.12) or further (P= 0.19) grafts. Preoperative active keratitis adversely affected survival (P= 0.123). The major cause of failure was graft rejection. Regrafts were more likely to fail from rejection episodes (P= 0.0005). Antiviral prophylaxis improved the outcome for rejection (P= 0.005) and reduced the incidence of HSK recurrence complicating rejection. Suppurative keratitis occurred in 12.4% of grafts as a complication of epitheliopathy including HSK recurrence. The outcome in these cases was particularly poor. Loose continuous graft sutures resulted in graft failure in 10.6% of grafts which may be improved by using interrupted suturing. Our results suggest the longterm prognosis for grafting in herpes simplex keratitis are not as good as may have been predicted from previous analyses.

The management of post-keratoplasty glaucoma by trabeculectomy

The results of 35 consecutive trabeculectomies in eyes developing medically uncontrollable glaucoma following penetrating keratoplasty are presented, with a mean follow-up of 3 years from the time of drainage surgery. Five eyes remained phakic until trabeculectomy was performed. Additional medical therapy was necessary to control the intraocular pressure in 32 eyes, which therefore were considered to have failed to be controlled by trabeculectomy and 90% of these failed within 6 months of filtration surgery. Despite additional medical therapy, in 17 eyes, further drainage surgery was required and 90% of this surgery took place within the first 14 months. Adverse prognostic factors were multiple grafts and synechial closure of the drainage angle.

The success and survival of repeat corneal grafts.

The results of 99 second grafts in individual eyes are reported. The five-year survival of these grafts was 49%. Allograft rejection was responsible for the majority of failures, but recurrence of host disease and endothelial decompensation were also important. Glaucoma was an important complication in 38% of eyes. Only 12 eyes in the series had no significant complication and 18 eyes achieved a corrected visual acuity of 6/12 or better.

Intraocular surgery following penetrating keratoplasty: The risks and advantages

Graft survival has been evaluated for patients who underwent subsequent intraocular surgery (extra-capsular cataract surgery or trabeculectomy) between 1983 and 1989. The patients were different from the majority of keratoplasty patients as evidenced by the indications for keratoplasty; corneal perforation was the indication in 24% of cases. Perforated and inflamed eyes were treated aggressively at the time of the acute event, including emergency keratoplasty and intensive topical steroids. Visco-elastic fluids were routinely used during secondary surgery and topical steroids were administered intensively post-operatively. The incidence of post-operative graft rejection was low (less than 14%). Rejection episodes were diagnosed early, prior to the appearance of a Khodadoust line, and were treated aggressively with intensive topical steroids. Glaucoma which was not controlled by topical therapy was surgically managed by trabeculectomy in the first instance. If this failed, tube drainage was performed and long-term topical steroids were administered. The only risk factor identified was uncontrolled glaucoma, P=0.1. The probability of graft survival (at five years) was 0.83 after cataract surgery and 0.62 after trabecuectomy, but wide confidence limits indicate the difference is not significant.

The role of penetrating keratoplasty in the management of microbial keratitis

Penetrating keratoplasty was performed as an emergency procedure in 52 eyes which had perforated from acute microbial keratitis and in a further 11 where perforation had not yet occurred. The results are compared with those of keratoplasty in 33 non-infected perforations and 20 eyes where there had been microbial keratitis which had responded to medical therapy leaving a scarred cornea. This latter group had both a better five year survival (90%) compared to all the others (51%), p<0.05, and achieved significantly better visual acuities, p<0.005.