Endothelial cell density after posterior lamellar keratoplasty: five- to seven-year follow-up.

PURPOSE: To report endothelial cell density (ECD) after posterior lamellar keratoplasty (PLK). DESIGN: Prospective, interventional case series. METHODS: In a single institution, PLK was performed in 15 eyes of 15 patients with pseudophakic bullous keratopathy (PPBK), Fuchs endothelial dystrophy (FED), or both. In 11 eyes, the donor tissue was inserted unfolded through a 9.0-mm sclerocorneal incision. In four eyes, the donor was folded and inserted through a 5.0-mm incision. The ECD measurements were performed in each patient at regular intervals until three years after surgery, and then in all patients simultaneously at 54 to 84 months after surgery. RESULTS: Three patients were not available for follow-up. One graft had decompensated. In the remaining 11 eyes, ECDs ranged from 368 to 1576 cells/mm(2). Monophasic and biphasic regression models of ECD against time were fitted for each technique separately. CONCLUSIONS: After PLK, ECD declined at a high rate. Both early- and longer-term loss rates may be related to surgical technique.

Biocompatibility of trypan blue with human corneal cells.

OBJECTIVE: To quantify the toxicity of trypan blue on human corneal cells according to exposure time and concentration. METHODS: Three in vitro experiments were performed. (1) We exposed cultured human corneal fibroblasts to trypan blue (0.0001% to 0.1%) in Eagle modified minimum essential medium (EMEM) or phosphate-buffered saline (PBS) for 15 minutes to 24 hours. Cytotoxicity was evaluated by Mosmann's colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MMT) assay. (2) We exposed human corneas in EMEM for 24 hours to trypan blue (0.001% to 0.1%). Fellow donor corneas served as controls. Endothelial survival was evaluated morphologically and by cell density assessment. (3) We morphologically compared the endothelial viability of human donor corneas after exposure to 0.1% trypan blue for 5 to 30 minutes with control corneas. RESULTS: In experiment 1, trypan blue in EMEM was not significantly toxic at concentrations of 0.005% or lower. Higher concentrations were toxic only after exposure to trypan blue for at least 6 hours. In PBS, significant toxicity was found after exposure to 0.1% trypan blue for 30 minutes or longer. Lower concentrations were toxic after longer exposures. In experiment 2, exposure to 0.01% and 0.1% trypan blue for 24 hours resulted in significant loss in cell density. At lower concentrations, the endothelium was affected only morphologically. In experiment 3, endothelial morphology changed in control corneas and after exposure to 0.1% trypan blue for as little as 5 minutes. After 30-minute exposure, morphologic deterioration was more pronounced. CONCLUSIONS: Trypan blue was toxic in vitro to corneal endothelium and corneal fibroblasts at higher concentrations and notably longer exposure times. Toxicity was less in EMEM than in PBS. Clinical Relevance At commonly used concentrations, both during cataract surgery and in the cornea bank, trypan blue is safe for corneal cells. At higher concentrations or longer exposures, however, caution is warranted.

Clinical and theoretical results of intraocular lens power calculation for cataract surgery after photorefractive keratectomy for myopia.

OBJECTIVES: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases. DESIGN: Nonrandomized, retrospective clinical study. PATIENTS AND METHODS: Nine patients (15 eyes) who underwent cataract surgery after prior PRK to correct myopia were identified. The medical records of both the laser and cataract surgery centers were reviewed. MAIN OUTCOME MEASURES: Eight different keratometric values (K values; measured or calculated) were entered into 3 different IOL calculation formulas: SRK/T, Holladay 1, and Hoffer Q. The actual biometry and IOL parameters were used to predict postoperative refraction, which was compared with the actual refractive outcome. Also, the relative underestimation of the refractive change in corneal dioptric power by keratometry after PRK was calculated. RESULTS: In 7 of 15 eyes, IOL exchange or piggybacking was performed because of hyperopia. Retrospectively, the most accurate K value for IOL calculation was found to be the pre-PRK K value corrected by the spectacle plane change in refraction. Use of the Hoffer Q formula would have avoided postoperative hyperopia in more cases than the other formulas. The mean underestimation of the change in corneal power after PRK varied from 42% to 74%, depending on the method of calculation. CONCLUSION: The predictability of IOL calculation for cataract surgery after PRK can be improved by using a corrected, refraction-derived K value instead of the measured, preoperative K value.

Endothelial cell density after deep anterior lamellar keratoplasty (Melles technique).

PURPOSE: To measure the recipient endothelial cell loss after the Melles technique for deep anterior lamellar keratoplasty. METHODS: In 21 eyes of 21 patients, a deep anterior lamellar keratoplasty procedure was performed. Before surgery and at 6, 12, and 24 months after surgery, specular microscopy was performed to evaluate the endothelial cell density. For each postoperative time interval, the mean endothelial cell loss relative to the preoperative value was calculated. RESULTS: Mean postoperative endothelial cell loss averaged 283 cells/mm(2) (+/- 293) at 6 months, 335 cells/mm(2) (+/- 309) at 12 months, and 421 cells/mm(2) (+/- 316) at 24 months. Estimate relative endothelial cell density losses obtained by mixed model analysis of variance were 11.1%, 2.0%, and 1.2%, respectively, each time compared with its previous measurement point. Second order comparisons showed that the loss within the first 6 months was significantly higher than after 6 months. CONCLUSION: In deep anterior lamellar keratoplasty, the recipient corneal endothelium showed a small initial drop in endothelial cell density followed by a physiologic rate of cell loss. Cell survival after lamellar keratoplasty may be expected to be better when compared with that following penetrating keratoplasty.

Degree of compatibility for HLA-A and -B affects outcome in high-risk corneal transplantation.

BACKGROUND: HLA-A/-B matching on a split typing level is more laborious, more expensive and offers less chances for a well-fitting match than does matching on the conventional broad typing level. It is important, therefore, to investigate whether or not split matching offers advantages and would, therefore, be advisable. METHODS: 303 high-risk patients out of 2,471 keratoplasty patients from 1982 through 1996, whose histories were all followed prospectively, could be re-evaluated retrospectively according to their broad or split matching levels ('good' vs. 'moderate'). RESULTS: Only a 'good' split level matching was significantly better than a 'moderate' one in the long run (up to 12 years). For the broad level matching this was only true for the first few years after keratoplasty. CONCLUSION: If only HLA-A/-B are matched and if only results longer than 3-4 years (up to 12 years) are taken into consideration, then split level matching offers clear-cut advantages over broad level matching.

Postoperative management and follow-up after corneal flap loss following laser in situ keratomileusis.

We present 3 cases of flap loss within 2 weeks of unilateral laser in situ keratomileusis. In all patients, spontaneous regeneration of the epithelial layer, covering the ablated stroma, was expected. In 2 patients, the best spectacle-corrected visual acuity recovered to 20/25 within 6 months and in 1 patient, a contact lens was fitted 6 months after the accident, restoring visual acuity to 20/25. The 6-month follow-up and the contact lens fitting technique are described.

Cyclotorsion: a possible cause of residual astigmatism in refractive surgery.

PURPOSE: To determine whether cyclotorsion occurs when a subject changes from binocular to monocular fixation and to assess positionally induced cyclotorsion. SETTING: Clinics of the Rotterdam Eye Hospital, Rotterdam, The Netherlands. METHODS: The axis of astigmatism was measured with the Nidek handheld keratometer in 15 normal subjects under monocular and binocular fixation and in seated and supine positions. The limits of agreement for the repeatability of measurements with the Nidek keratometer were used to identify subjects with statistically significant cyclotorsion. RESULTS: Two subjects (13%) showed statistically significant excyclotorsion when changing from binocular to monocular fixation in a seated position. In a supine position, 3 subjects (20%) showed excyclotorsion when the fixation changed. Body position itself had no influence on ocular torsion. CONCLUSIONS: Significant cyclotorsion may occur under monocular viewing conditions. If monocular photorefractive keratectomy procedures are based on binocular keratometry readings, an undercorrection of myopic astigmatism may result. Individuals at risk should be identified before refractive keratectomy is performed.

Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus.

PURPOSE: To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. SETTING: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS: Three groups of patients with low myopia correction (spectacles, soft contact lens, and Intacs) and 4 groups with high myopia correction (spectacles, rigid contact lens, Artisan claw lens, and laser in situ keratomileusis [LASIK]) had through-focus contrast sensitivity measurements to establish the myopic shift and depth of focus. From these 2 parameters, spherical and irregular aberrations were determined using theoretical eye models and geometric optics. Visual acuity, stray light, and predictability were also studied. RESULTS: There were no differences in best corrected visual acuity (BCVA) or best corrected contrast sensitivity between the low myopia groups. The Intacs group had a significantly larger depth of focus (P<.05). The results in the soft contact lens group were comparable to those in a human eye model with an average amount of spherical and irregular aberrations. The LASIK group had worse uncorrected visual acuity (UCVA) and best corrected contrast sensitivity than the spectacles, rigid contact lens, and Artisan claw lens groups (P<.05) due to the amount of spherical and irregular aberrations present after LASIK. The low and high myopia spectacles groups had average amounts of spherical and irregular aberrations. CONCLUSIONS: Neither surgical techniques nor contact lenses resulted in BCVA or best corrected contrast sensitivity that surpassed the values measured in the best corrected spectacles groups. The Artisan claw lens performed better than LASIK in UCVA, predictability, and best corrected contrast sensitivity.

Long-term outcome in high-risk corneal transplantation and the influence of HLA-A and HLA-B matching.

PURPOSE: To evaluate long-term follow-up of high-risk corneal transplants allocated after matching for broad HLA-A and HLA-B antigens and to establish whether matching for HLA-A and -B antigen "splits" would result in a reduced risk of immunologic graft failure. METHODS: A total of 303 high risk corneal transplants was included. Class I antigen-matched donor corneas were obtained using broad HLA-A and -B antigen data and accepting 0 or 1 mismatch at each locus. Analysis of HLA antigens was performed also on the split typing level. The influence on immunologic graft failure for an increasing number of matched class I antigens based on split typing was analyzed with Kaplan-Meier statistics and Cox regression. Graft survival and indication for transplantation were investigated. RESULTS: Rejection was the cause of 34% of all graft failures. A significantly higher immune failure free graft survival was found in a group with 0 or 1 HLA-A and -B mismatch based on split typing (log-rank test, P = 0.002). A beneficial effect of matching for split antigens was shown with multivariate analysis (odds ratio, 0.41). CONCLUSIONS: One third of graft failures in our high-risk population was caused by irreversible graft rejection. Allocation of donor corneas based on a 0 or 1 split antigen mismatch at both HLA-A and -B loci could contribute to a higher immune failure free graft survival and could result in a higher overall graft survival.

Recovery of the visual acuity in a family with Reis-Bückler dystrophy.

BACKGROUND: The hereditary Reis-Bückler dystrophy is one of the anterior localised corneal dystrophies with superficial reticulated opacities, sometimes in combination with recurrent attacks of corneal erosion. Phototherapeutic keratectomy (PTK) is now the first method to consider for managing this disease when intervention is required. METHODS: We treated six eyes of four related patients with Reis-Bückler dystrophy, who had a demonstrable reduction in visual acuity due to corneal opacities within their virgin corneas (three eyes), penetrating (one eye) or lamellar (two eyes) grafts. We present the results of change in visual acuity and best corrected spherical spectacle and contact lens refraction at 1 year following surgery. In one case, we had to fit a rigid contact lens to correct the hyperopic shift which caused anisometropia. RESULTS: The mean spherical refractive change 1 year after PTK surgery was 0.33+/-S.D., 1.8D. A hyperopic shift was observed in four eyes. Visual acuity remained stable in all patients 1 year after surgery. The central corneal area remained clear, and mean best spectacle corrected visual acuity improved from +0.8 logMAR before PTK to +0.15 logMAR after 1 year. There was no significant change (P>0.8) between the mean 1 year best spectacle corrected visual acuity (+0.125 log MAR +/- S.D. 0.15) and the best contact lens corrected visual acuity (+0.108 log MAR +/- S.D. 0.16). After fitting a contact lens in one patient to correct anisometropia, the hyperopic shift did not change significantly during 12 months of follow-up. It was not necessary to adjust the lens parameters. One patient required cataract surgery. CONCLUSION: PTK corneal surgery is the treatment of first choice when intervention is required in patients with Reis-Bückler dystrophy because it is safe and much less invasive than lamellar or penetrating keratoplasty. Contact lens fitting following PTK has not changed corneal shape.

Effect of oral acyclovir after penetrating keratoplasty for herpetic keratitis: a placebo-controlled multicenter trial.

OBJECTIVE: To determine the prophylactic effect of oral acyclovir on the recurrence rate of herpetic eye disease after penetrating keratoplasty. DESIGN: A randomized, double-masked, placebo-controlled multicenter trial. PARTICIPANTS: Sixty-eight consecutive patients (68 eyes) with corneal opacities due to herpetic eye disease who underwent penetrating keratoplasty. INTERVENTION: Oral acyclovir 400 mg twice daily or placebo tablets for 6 months. MAIN OUTCOME MEASURES: The recurrence rate of herpetic eye disease-related events and rejection episodes, proven by viral cell culture or polymerase chain reaction. RESULTS: During the 2-year follow-up period, there were 3 culture-proven herpetic eye disease recurrences in the acyclovir group and 9 in the placebo group. Lifetime survival analysis of the probability of remaining free from recurrence revealed a significantly reduced risk of recurrent herpetic disease in the acyclovir-treated group. CONCLUSION: This study suggests that oral acyclovir effectively prevents herpes-related recurrences after penetrating keratoplasty in herpetic eye disease.