W. H. Beekhuis

A new surgical technique for deep stromal, anterior lamellar keratoplasty

AIMS To describe a new surgical technique for deep stromal anterior lamellar keratoplasty. METHODS In eye bank eyes and sighted human eyes, aqueous was exchanged by air, to visualise the posterior corneal surface−that is, the “air to endothelium” interface. Through a 5.0 mm scleral incision, a deep stromal pocket was created across the cornea, using the air to endothelium interface as a reference plane for dissection depth. The pocket was filled with viscoelastic, and an anterior corneal lamella was excised. A full thickness donor button was sutured into the recipient bed after stripping its Descemet’s membrane. RESULTS In 25 consecutive human eye bank eyes, a 12% microperforation rate was found. Corneal dissection depth averaged 95.4% (SD 2.7%). Six patient eyes had uneventful surgeries; in a seventh eye, perforation of the lamellar bed occurred. All transplants cleared. Central pachymetry ranged from 0.62 to 0.73 mm. CONCLUSION With this technique a deep stromal anterior lamellar keratoplasty can be performed with the donor to recipient interface just anterior to the posterior corneal surface. The technique has the advantage that the dissection can be completed in the event of inadvertent microperforation, or that the procedure can be aborted to perform a planned penetrating keratoplasty.

A TECHNIQUE TO VISUALIZE CORNEAL INCISION AND LAMELLAR DISSECTION DEPTH DURING SURGERY

PURPOSE To describe a surgical technique to visualize the depth of corneal incisions and lamellar stromal dissections during surgery. METHODS In porcine cadaver eyes, the aqueous was exchanged by air. Thus an air-to-endothelium interface (i.e., a useful optical surface) was created at the posterior corneal surface. The air-to-endothelium interface was used as a reference plane to visualize the corneal thickness and the relative depth of corneal incisions and dissections. Freehand peripheral corneal incisions, tangential keratotomy incisions, and lamellar stromal dissections were made at an intended corneal depth of 60, 80, and 99%. Light microscopy was used to measure the relative depth of the incisions and dissections. RESULTS Achieved depth for peripheral corneal incisions averaged 65.2+/-5.3%, 78.8+/-5.1%, and 93.4+/-6.0%, respectively (p<0.05); and for tangential keratotomy incisions, 68.2+/-7.3%, 83.2+/-4.4%, and 95.8+/-3.6%, respectively (p<0.05). Achieved depth for lamellar stromal dissections averaged 58.3+/-9.4%, 81.1+/-3.4%, and 94.4+/-1.5%, respectively (p<0.05). Microperforations occurred with three incisions made at 99% intended depth. CONCLUSION During surgery, the depth of incisions and lamellar dissections relative to the corneal thickness can be visualized by filling the anterior chamber with air (i.e., by creating an optical interface at the posterior corneal surface).

Silicone oil keratopathy: indications for keratoplasty.

A penetrating corneal graft was performed in 12 patients for corneal opacification induced by silicone oil. The patients were all aphakic. They had had vitrectomy and silicone oil injection for complicated retinal detachment, often with periretinal proliferation. The average follow-up time was 13.7 months, during which four out of 11 grafts failed (one case was lost to follow-up). One patient developed severe calcific band keratopathy, and three grafts failed from endothelial decompensation. Changes induced by silicone oil include band keratopathy, thinning, and endothelial damage. The indications for keratoplasty for these corneal changes are discussed.

CAUSES OF HIGH ASTIGMATISM AFTER PENETRATING KERATOPLASTY

We retrospectively evaluated the factors which might have caused excessive corneal astigmatism after penetrating keratoplasty (PKP) in 29 eyes, in which surgical correction of astigmatism was indicated. In 18 eyes high astigmatism (5 diopters or more) existed before suture removal probably due to graft elevation (3×), wound dehiscence (3×), wound configuration abnormalities such as ovality/overcut (8×), and a thin recipient cornea (2×). The cause was unknown in 2 eyes. In 19 eyes the astigmatism considerably increased after all sutures were removed; astigmatism increased an average of 8.8 diopters (range, 5 to 16.5 D). Ten of these 19 patients showed graft elevation, despite the fact that the sutures were only removed after an average 22.9 months. In 3 other patients the astigmatism gradually increased over the years, long after suture removal; two of these showed graft elevation. The study demonstrates the possible instability of keratoplasty wounds, the change in astigmatism after suture removal, and the late apparently spontaneous changes in astigmatism after PKP in some eyes.

Unusual deposits in the superficial corneal stroma following combined use of topical corticosteroid and beta-blocking medication.

Clinical observation of eight patients with superficial stromal precipitation of calcium phosphate is presented. In all cases the predisposing factors for the formation of these depositions were: epithelial defects and the combined use of topical dexamethason phosphate or prednisolon phosphate with topical beta-blocking agents. In two patients the medication that gave rise to these precipitates was used without preservatives, suggesting that the medication itself and not the preservatives contribute to the deposits. Discontinuance of simultaneous administration of the steroids and beta-blocking agents prevented further formation of precipitates. The authors suggest an interaction between simultaneously given steroid and betablocking agents, giving rise to calcium phosphate precipitates when an epithelial defect is present which allows easy access to the superficial corneal stroma.

Corneal Graft Survival in HLA-A- and HLA-B-Matched Transplantations in High-Risk Cases with Retrospective Review of HLA-DR Compatibility

&NA; In 107 HLA‐A‐ and HLA‐B‐matched corneal transplantations performed in high‐risk patients, the 3‐year graft survival was 60.5%. The criteria used for the definition of high risk were vascularization of the recipient cornea and/or one or more previous failed grafts; they were also the indications for HLA typing and matching. Donor/recipient compatibility was defined by the presence of only 0 or 1 HLA‐A or HLA‐B mismatches. When nonimmunological factors leading to graft failure were excluded, the 3‐year survival was 76.3%. During that follow‐up period, a total of 33 grafts failed; in 13 cases, the cause was allograft rejection. When only first transplants were considered, a 3‐year graft survival of 81.0% was observed. Retrospective DR typing was possible in 33 cases. Because only three graft rejections occurred in that group, we were unable to assess the importance of DR compatibility on the survival of corneal allografts.

Toxic keratopathy due to the accidental use of chlorhexidine, cetrimide and cialit

Due to economical reasons some ophthalmologists are using an irrigating solution made by the hospital pharmacy instead of the commercially available solutions. These irrigating solutions come in bottles which are identical to the ones used for other solutions. During the last three years bottles were accidentally mixed up five times. Consequently, bottles containing solutions such as chlorhexidine, cetrimide, chlorhexidine/cetrimide and cialit solutions were used during cataract surgery. This resulted in immediate corneal edema which, in its turn resulted in a bullous keratopathy. Four patients underwent a penetrating keratoplasty. In one patient the cornea was covered with a conjunctival flap. Light microscopy of the corneas included epithelial edema, loss of keratocytes, and a disrupted and sometimes absent endothelial cell layer.

Results of penetrating keratoplasty for pseudophakic bullous keratopathy with the exchange of an intraocular lens

We report on 29 consecutive patients with pseudophakic bullous keratopathy who underwent in one eye penetrating keratoplasty with an exchange of the original intraocular lens for a Pearce tripod posterior chamber lens, and who were available for a follow up of at least 12 months. The average interval between cataract extraction with lens implantation and the appearance of bullous keratopathy was five and a half years (range 10 months to 16 years). The mean follow-up period after penetrating keratoplasty was 36 months (range 12 to 56 months). The corneal graft remained clear in 22 (76%) eyes. One year after the operation 45% of the eyes had a vision of 20/40 or better, and 20% had visual acuities between 20/40 and 20/100. The remaining 31% had a vision of 20/100 or less (one unknown). Nine eyes (31%) had cystoid macular oedema or macular degeneration. 45% of the eyes had a refraction within approximately 2 dioptres of emmetropia. In patients with pseudophakic corneal oedema we continue to exchange the intraocular lens by a Pearce tripod posterior chamber lens sutured to the iris when it is necessary to remove the lens.

CROHN'S COLITIS AND THE CORNEA

Ulcerative colitis (Crohns disease) is a chronic relapsing inflammatory bowel disease of unknown etiology. The most common ocular complications include conjunctivitis and uveitis, particularly iritis. Herein, we describe a patient who had a decrease in visual acuity due to an increasing astigmatism. This was accompanied with a peripheral limbal thinning of the cornea and faint confluent corneal changes. No systemic activity was present during the period that the patient was monitored. Changes of astigmatism were followed up with videokeratography. This apparatus monitors changes in clinical course accurately and makes comparison possible between separate visits.

Infectious crystalline keratopathy

In seven patients white branched crystalline opacities, which grew very slowly, were seen in the corneal stroma. They were associated with very little inflammatory activity, so that the clinical picture at first did not suggest an infectious etiology. Pathological examination, however, demonstrated colonies of bacteria between intact corneal lamellae. On bacterial examination gram-positive commensals were mainly found.All the patients described so far were found to be taking corticosteroids regularly, sometimes in combination with antibiotics. The immunosuppression brought about by corticosteroids is probably an important factor in the development of these crystalline opacities.The therapy for this infectious crystalline keratopathy is difficult and lengthy. It consists of local bactericidal antibiotics and the lowest possible dosage of corticosteroids, if necessary combined with a partial lamellar keratectomy and removal of the affected corneal tissue by fraising.