Evaluation and transplantation of corneas from pseudophakic donor eyes.

PURPOSE: To evaluate the quality of corneal donor tissue from pseudophakic eyes for transplantation. METHODS: Only capsular-supported posterior chamber pseudophakia was studied. Forty-five pairs of donor eyes were assessed and evaluated by standard Minnesota Lions Eye Bank (MLEB) protocol. Thirty-three pairs were unilaterally pseudophakic with the unoperated phakic eye used as a control eye. Twelve donors were bilaterally pseudophakic. All corneas were rated for corneal clarity, epithelial defects, stromal edema, Descemet's membrane folding, endothelial cell density (ECD), and cell damage by slit-lamp examination and specular microscopy. If the corneas were not transplanted, the endothelium was vital stained with trypan blue and counterstained with alizarin red S for quantitation, localization, and visualization of cell morphology and damage. RESULTS: Sixty-eight of the 90 corneas in this study did not meet transplantation criteria. A significant difference in ECD (>22%) and in overall corneal rating was found in seven (21%) of 33 pairs of unilateral pseudophakic donors. Fourteen corneal transplants were performed using corneas from the donors in this study. Nine corneas from pseudophakic donor eyes were transplanted, resulting in one primary graft failure reported. CONCLUSION: Corneas from pseudophakic donor eyes may need more extensive evaluation for endothelial viability than is currently required by eye bank standards.

A new, simple, nonradioactive, nontoxic in vitro assay to monitor corneal endothelial cell viability.

PURPOSE: This study was designed to determine whether Alamar blue could be used to evaluate corneal endothelial cell viability in vitro. METHODS: Alamar blue incorporates a proprietary redox indicator that changes color in response to metabolic activity. Primary rabbit endothelial cells were subcultured on 96-well plates at densities ranging from 1,250 to 40,000 cells per well. After 12 hours' incubation, Alamar blue was added to each well and absorbance measured hourly from 1 to 9 hours. Sodium azide-killed cells were used as a control. Alamar blue conversion was also compared with [3H]-thymidine incorporation in the presence or the absence of mitomycin C. RESULTS: Alamar blue reduction demonstrated endothelial cell viability at all cell concentrations compared with that in killed-cell controls. The reduction varied proportionately with cell number and time, showing clearly significant differences. Conversely, [3H]-thymidine uptake demonstrated minimal DNA synthesis and little or no ability to distinguish cell number or viahility. CONCLUSIONS: Alamar blue reduction measures endothelial cell viability and can readily differentiate cell concentrations. It demonstrates several advantages over [3H]-thymidine: It can assay nonproliferating endothelial cell metabolism, it allows rapid assessment of large numbers of samples, it can differentiate endothelial cell concentrations, it is nontoxic, it is nonradioactive and allows for simple disposal, it is less costly, and it allows for continuous monitoring of endothelial cell metabolism and viability.

Comparison between the refractive results of combined penetrating keratoplasty/transsclerally sutured posterior chamber lens implantation and the triple procedure.

PURPOSE: We determined how accurately we could predict the intraocular lens (IOL) power for a combined penetrating keratoplasty and transsclerally sutured posterior chamber lens implantation procedure (PK/TS-SPCL) compared with the Triple procedure (penetrating keratoplasty, extra-capsular cataract extraction, and IOL insertion). METHODS: We retrospectively evaluated the postoperative refractive results of 27 patients who had undergone PK/TS-SPCL and compared them with those of 46 patients who had undergone a Triple procedure. All patients with a final visual acuity > 20/50 who had surgery at the University of Minnesota between January 1988 and December 1993 were included in this study. RESULTS: The mean postoperative deviation from the predicted refractive error was 1.79 D for the Triple group and 1.81 D for the PK/TS-SPCL group (p = 0.95). Sixty-three percent of the Triple patients and 67% of the PK/TS-SPCL patients were within -2.00 D and +2.00 D of their predicted refractive error. As a group, the Triple patients had a mean postoperative keratometry reading of 44.64 compared with 45.58 for the PK/TS-SPCL patients (p = 0.12). CONCLUSION: These results indicate that our accuracy in predicting the IOL implant power in PK/ TS-SPCL is quite comparable with that obtained for the Triple procedure, and our refractive results for each group are quite similar.

Povidone-iodine (betadine) in the treatment of experimental Pseudomonas aeruginosa keratitis.

Topical 5% povidone-iodine for the treatment of corneal ulcers was observed in Sierra Leone, West Africa by one of us (D.J.D.). To test the efficacy of topical 5% povidone-iodine for infectious keratitis, experimental Pseudomonas aeruginosa keratitis was induced in 12 rabbits by first abrading the central 3 mm of corneal epithelium. Thirty milliliters of broth of P. aeruginosa strain ATCC 27835 (1.8 x 10(7) viable bacteria) was dropped twice on the wounded cornea. After 22 h, all corneas were clinically infected. Eight rabbits were treated with 5% povidone-iodine solution and four with 0.9% NaCl solution. All were given hourly drops. Twenty-four hours after treatment began, the central 8-mm button of the infected cornea was excised, homogenized, and serial dilutions plated onto MacConkey agar. The total number of viable Pseudomonas organisms was calculated. The treatment group had 5.2 +/- 0.4 CFUs (colony-forming units) per cornea. The control group had 4.8 +/- 0.4 CFUs per cornea (p = 0.11). The clinical scores (Hobden grading system) were 6.9 +/- 1.5 for the treated group and 7.3 +/- 2.5 for the control group (p = 0.74). There was no statistical difference between the treated and control groups. Povidone-iodine (5%) is not effective in the acute treatment of P. aeruginosa keratitis in this rabbit model.

Tissue utilization at the Minnesota Lions' Eye Bank.

The purpose of this study was to examine the utilization of corneas procured by the Minnesota Lions' Eye Bank to determine why corneas were excluded from transplantation and to identify methods to safely increase the number of tissues made available for transplantation. We performed a retrospective review of the eye bank charts of 2,382 corneas evaluated by the Minnesota Lions' Eye Bank between December 1, 1992 and November 30, 1993. During that time 748 corneas (31%) were made available for transplantation; 1,597 (67%) were directed toward research or training. Thirty-seven corneas (1.5%) were disposed of for safety reasons. Six hundred and sixty of the corneas which were excluded from transplantation (40%) were excluded for a donor aged over 75 years. Three hundred and ninety-one corneas (24%) were rejected because of a contraindication in the donor's past ocular or medical history. Another 395 corneas (24%) were excluded for poor tissue quality. The most common reason for exclusion of tissue based on tissue quality was abnormalities seen on specular microscopic examination (200 corneas). Of interest, only 14 corneas were rejected for low endothelial cell counts. This review of our tissue evaluation process has led us to reevaluate and change our policy regarding exclusion of corneas for epithelial defects and arcus senilis. These data suggest that further evaluation of the abnormalities seen on specular microscopic examination and their validity as exclusion criteria should be undertaken. Other areas for further evaluation are how to improve the timeliness of tissue procurement and whether excluding all tissues over age 75 years and all postsurgical eyes is valid.

Mottled cyan opacification of the posterior cornea in contact lens wearers.

PURPOSE: We studied patients who had mottled cyan-colored opacities of the cornea to better understand the cause and prognosis of this entity. METHODS: We reviewed examinations of patients who had a mottled cyan opacification of the cornea. Risk factors, including contact lens wear and exposure to heavy metals, were analyzed. Clinical findings, pachymetry specular microscopy, and progression of the abnormality were noted. RESULTS: Six patients who had a mottled cyan opacification at the level of Descemet's membrane were identified. These opacities were located in the peripheral and midperipheral cornea. All patients had bilateral findings, had visual acuities of 20/20 or better, and were asymptomatic. All patients had worn soft contact lenses bilaterally for periods ranging from seven to 14 years. CONCLUSION: All patients had the similar clinical appearance of a mottled cyan opacification at the level of Descemet's membrane in the peripheral cornea. Long-term contact lens wear appears to be associated; however, the exact cause is unclear.

Results one year after using the 193-nm excimer laser for photorefractive keratectomy in mild to moderate myopia.

As part of a clinical trial, photorefractive keratectomy using the VISX 2015 193-nm excimer laser was performed on 91 healthy eyes of 91 patients. Preoperative refractive errors (spherical equivalent) ranged from -1.00 to -7.50 diopters (mean, -4.16 +/- 1.41 diopters). No patient had more than 1 diopter of refractive astigmatism. Six months postoperatively, the average residual refractive error was +0.09 +/- 0.63 diopters (range, -2.13 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity of 20/40 or better was attained in 86 eyes (95%) and was 20/25 or better in 67 eyes (74%). At one year, follow-up information was available on 85 eyes of 85 patients. The average residual refractive error was -0.15 +/- 0.65 diopters (range, -2.50 to +1.63 diopters). Correction within 1 diopter of that attempted was attained in 85 eyes (93%). Uncorrected visual acuity was 20/40 or better in 83 eyes (98%) and was 20/25 or better in 68 eyes (80%). One patient lost three lines of best-corrected visual acuity because of corneal haze, dropping from 20/15 to 20/30, whereas all other patients returned to best-corrected visual acuity within one line of their preoperative best-corrected visual acuity. Photorefractive keratectomy with the 193-nm excimer laser appears to be a useful treatment modality for the reduction of mild to moderate myopia.

193-nm excimer photorefractive keratectomy in high myopia.

PURPOSE: To evaluate the refractive results of 193-nm excimer laser photorefractive keratectomy (PRK) performed on 48 highly myopic eyes in a multicenter study. METHODS: A Visx 2015 or 2000 argon-fluoride excimer laser and a single-zone ablation technique were used. Postoperatively, eyes were treated with topical fluoromethalone for up to 5 months. Most eyes were treated with a 6.0- to 6.2-mm beam diameter after undercorrections and increased regression were noted with a 5.5-mm beam in earlier studies. Forty-eight eyes were treated for myopia, which was between -8.0 and -15.25 diopters (D) (spherical equivalent). The mean preoperative refraction was -11.2 D. Retreatment was performed after 6 to 16 months on 11 eyes for undercorrection. All eyes not retreated were followed for at least 12 months. RESULTS: At 6 months, follow-up was available on 47 eyes. Of these eyes, 40% and 64% achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 60% of eyes attained 20/40 visual acuity or better uncorrected. Eleven patients (23%) were retreated between 6 to 16 months for undercorrection and/or regression. After retreatment, 47% and 81% of eyes achieved corrections within 1 and 2 D of attempted correction, respectively. At 1 year, 15% of eyes lost two lines of best-corrected visual acuity, and no eyes lost more than two lines. There was slightly more corneal haze seen in this group compared with the haze seen in patients undergoing PRK for low and moderate myopia. CONCLUSIONS: These data show that excimer PRK can correct high amounts of myopia with reasonable stability after 6 months. Excimer PRK is an effective surgical treatment of severe myopia, but long-term follow-up is still needed to assess the stability of its effect.

Whole globe enucleation versus in situ corneal excision: a study of tissue trauma and contamination.

Twenty-four pair of eyes donated to the Minnesota Lions Eye Bank were studied to determine the effect of corneal procurement methods on tissue quality. Eyes studied were ineligible for transplantation because of a preexisting medical condition other than sepsis or age of > 75 years. The procurement technique was randomized for each donor. One cornea was procured in situ (IS), whereas the fellow eye was enucleated and processed in the laboratory (EN). Procurement protocols were standard Eye Bank Association of America methods. Tissue characteristics were scored according to standard eye bank protocols. Cultures were performed at the time of tissue procurement and following storage for 7 days in Dexol media. With the exception of endothelial striae, no statistical difference was found between groups for any tissue characteristics. The average score for endothelial striae in the IS group was greater than twice that of the EN group. Initial cultures were positive in 10 of 24 in the IS group and four of 24 in the EN group. Each group had three positive end-storage cultures. These results demonstrate superior tissue decontamination after initial processing and less endothelial cell trauma with standard enucleation when compared to in situ corneal excisions.

Use of the 193 nm excimer laser for photorefractive keratectomy in low to moderate myopia.

As part of a Phase III clinical trial, photorefractive keratectomy using the VISX 2015 193 nm excimer laser was performed on 91 sighted eyes of 91 patients. Preoperative refractive errors (spherical equivalent) ranged from -1.00 diopters (D) to -7.50 D (mean -4.11 D +/- 1.43 D). At six months, average residual refractive error was 0.02 D +/- 0.64 D (range -2.21 D to +1.38 D). Ninety-three percent of eyes were within 1.00 D of attempted correction, 93% had uncorrected visual acuity of 20/40 or better, and 72% achieved uncorrected visual acuity of 20/25 or better. All patients returned to their best corrected visual acuity within one line of their preoperative best corrected visual acuity. Photorefractive keratectomy with the 193 nm excimer laser appears to be useful in reducing low to moderate myopia.

Clinical and anatomical study of the effect of transscleral fixation of posterior chamber lenses on early postkeratoplasty astigmatism.

We reviewed the pattern of astigmatism after penetrating keratoplasty and transsclerally sutured posterior chamber lens (TSPCL) placement in 73 patients. Thirty-five patients (48%) had an axis of astigmatism oriented perpendicularly to the haptics of the TSPCL. Twenty-seven patients (37%) had an orientation of astigmatism that was in the same meridian of the haptics of the TSPCL. Eleven patients (15%) had an axis of astigmatism oriented obliquely to the meridian of the haptics of the TSPCL. The distance the haptic fixation sutures were placed behind the limbus appeared to be correlated with the orientation of astigmatism. Patients having the lens fixated within 0.75 mm of the limbus were more likely to have astigmatism oriented perpendicular to the meridian of the haptics of the posterior chamber lens in the early postoperative period. Patients having the lens fixated 2-3 mm posterior to the limbus were more likely to have astigmatism oriented in the same meridian as the haptics of the posterior chamber lens in the early postoperative period. In an eye bank model of TSPCLs during penetrating keratoplasty, the placement of a posterior chamber lens with haptics fixated within 0.75 mm of the limbus significantly widens the recipient bed an average of 0.3 mm in the meridian of the haptics of lens placement (p = 0.02). When the posterior chamber lens haptics were fixated 3 mm posterior to the limbus, the recipient bed was significantly narrowed in the meridian of lens placement an average of 0.2 mm (p = 0.02). It appears that the TSPCLs may have an effect on early postkeratoplasty astigmatism by distorting the corneal wound at the time of keratoplasty.

Betadine decontamination of donor globes.

Between May 1983 and December 1989, 2,921 donor eyes received by the Minnesota Lions Eye Bank underwent a decontamination protocol using 10% Betadine (1% povidone-iodine) solution. Positive pretreatment limbal cultures were obtained on 52.1% of donor eyes. Posttreatment limbal cultures demonstrated a 76.1% reduction in microbial growth, including an 85.7% reduction in Candida species. Streptococcus species were reduced by 76.7% and coagulase-negative Staphylococcus were reduced by 76.1%. In addition, of 250 donor rims obtained at the time of surgery, two had coagulase-negative. Staphylococcus present that were also present after the decontamination procedure. In no cases did endophthalmitis occur during this study. This study demonstrates that this protocol using 10% Betadine solution is extremely effective in decontaminating donor globes of aerobic bacteria and fungi. However, gentamicin-resistant organisms survived this protocol, emphasizing the need to develop storage media containing a broader-spectrum antibiotic agent then gentamicin.

Clinical findings in Brown-McLean syndrome.

The Brown-McLean syndrome is a clinical condition with corneal edema involving the peripheral 2 to 3 mm of the cornea. The edema typically starts inferiorly and progresses circumferentially, but spares the central portion of the cornea. Additionally, the edema is associated with a punctate orange-brown pigmentation on the endothelium underlying the edematous areas. Central cornea guttata is frequently seen. This condition occurs most frequently after intracapsular cataract extraction, but may also occur after extracapsular cataract extraction and phacoemulsification, or pars plana lensectomy and vitrectomy. Surgical complications and multiple intraocular procedures are frequently observed in these patients. Less frequently, the Brown-McLean syndrome can occur in eyes that have not had surgery. We studied the clinical characteristics of 43 affected eyes of 32 patients. New findings included Brown-McLean syndrome occurring in two eyes of a phakic patient with intermittent angle-closure glaucoma. Two eyes developed Brown-McLean syndrome after phacoemulsification and one eye developed peripheral edema after pars plana vitrectomy and lensectomy. Additionally, severe, infectious keratitis occurred after rupture of peripheral bullae in two eyes. Patients with this condition should be examined periodically and educated regarding the early clinical signs of corneal ulceration.

Stability of refraction and visual acuity during 5 years in eyes with simple myopia. The PERK Study Group.

BACKGROUND: Normal ranges of variability of refraction and visual acuity in adult myopic eyes are needed as a reference standard for assessing the stability of refractive corneal surgery. METHODS: We measured the changes in spectacle-corrected visual acuity and cycloplegic refraction during 5 years for the unoperated eye of 82 patients aged 21 to 57 years in the Prospective Evaluation of Radial Keratotomy Study. The changes were compared for contact lens and non-contact lens wearers. We also compared the 5-year cycloplegic and manifest refractions for these unoperated eyes. RESULTS: Of 77 eyes, 44% gained or lost one Snellen line and 48% experienced no change in spectacle-corrected visual acuity between baseline and 5 years. Only one eye (1%) lost two lines, and 7% gained two lines. The refractive change was less than 1.00 D for 84% of the 37 non-contact lens wearing eyes. Only 13% became more myopic by at least 1.00 D (maximum increase in myopia, 2.00 D), and 3% became less myopic by 1.00 D. Of 45 contact lens wearing eyes, 38% became more myopic by at least 1.00 D. The 5-year manifest refraction was 0.50 D to 1.50 D more myopic than the cycloplegic refraction for 37% of eyes. CONCLUSIONS: We recommend using two or more Snellen lines as the standard for a meaningful change in spectacle-corrected visual acuity in operated eyes, and 1.00 D as a meaningful cutoff for stability of refraction. The wearing of contact lenses can confound the results of stability studies. The difference between the cycloplegic and manifest refractions suggests that the cycloplegic refraction should be used in planning for refractive surgery.

Avellino corneal dystrophy. Clinical manifestations and natural history.

PURPOSE: The pathologic features of a variant of granular corneal dystrophy has been described in which the presence of lattice changes in addition to characteristic granular lesions has been documented. The authors investigated the mode of inheritance, natural history, and clinical manifestations of this dystrophy. METHODS: A family with this condition was investigated, and a pedigree was established. Family members underwent ophthalmic examination, and ophthalmic history was obtained. In addition, pathologic examination of corneal tissue from affected patients was performed. RESULTS: Similar to the four previously described cases, this family also traced its origins to Avellino, Italy. This autosomal dominant condition affected 27 of 92 family members, ranging in age from 5 to 77 years. Granular deposits were the earliest and most common manifestations. Lattice lesions were present in some patients with granular lesions. Older patients had anterior stromal haze between deposits, which impaired visual acuity. Recurrent granular deposits were noted in donor corneal tissue after penetrating keratoplasty for this condition. Pathologic examination of corneal tissue from affected patients confirmed the presence of hyaline material seen in granular dystrophy as well as fusiform deposits of amyloid, similar to those seen in lattice dystrophy type I. CONCLUSION: This study establishes the natural history and clinical manifestations of this condition.

Penetrating keratoplasty and transscleral fixation of posterior chamber lens.

We reviewed the outcome in 115 patients who underwent penetrating keratoplasty and transscleral fixation of a posterior chamber lens. One patient died soon after surgical procedures, and nine patients were lost to follow-up, leaving a cohort of 105 patients. Mean follow-up time was 26.8 months (range, six to 43 months). Visual acuity of 20/40 or better was found in 29 patients (27.6%) and 20/50 to 20/200 in 37 patients (35.2%). Reasons for poor visual outcome included cystoid macular edema in ten patients (9.5%), age-related macular degeneration in six patients (5.7%), and retinal detachment in four patients (3.8%). None of the patients developed lens decentration. There were no instances of hyphema and only one patient had a perioperative limited suprachoroidal hemorrhage. New-onset increase in intraocular pressure developed in 20 of 66 patients (30.3%). Analysis of the 39 patients with preoperative increase in intraocular pressure that required medical treatment demonstrated an improvement in 13 patients (33.3%), worsening in 12 patients (30.8%), and unchanged status in 14 patients (35.9%). The exposed haptic suture was covered by using one of the following three alternative methods: a conjunctival flap, a scleral flap, or a corneal tissue button. Exposure of the haptic suture through the conjunctiva was a complication in 21 patients (20%). Of these 16 (76.1%) occurred in the group with a conjunctival covering, five (23.8%) occurred in the group with a scleral flap, and none occurred in the corneal tissue button group. This study demonstrated that transscleral fixation of a posterior chamber lens is a viable option in the treatment of patients undergoing penetrating keratoplasty and intraocular lens implantation with absent capsular support.

Persistent superficial punctate keratitis after resolution of chlamydial follicular conjunctivitis.

Two cases of follicular conjunctivitis due to Chlamydia trachomatis followed by punctate epithelial keratitis are described. Both cases were initially treated with either oral tetracycline or doxycycline with resolution of the follicles. These two patients subsequently had recurrent, bilateral grayish lesions at various levels in the corneal epithelium that stained in a punctate fashion with fluorescein. There was anterior stromal edema associated with some of these lesions in one case. The lesions were confined mostly to the central cornea. These recurrent lesions were unassociated with a conjunctival reaction, were unresponsive to oral tetracycline, but were exquisitely responsive to low doses of topical steroids. Chlamydial conjunctivitis and the associated keratitis typically shows no response or actual exacerbation of symptoms with topical steroids, and the keratitis shows a predilection for the upper half of the cornea. These patients demonstrate that chlamydial keratoconjunctivitis might result in a clinical appearance consistent with Thygeson's superficial punctate keratitis.

Early postkeratoplasty astigmatism following placement of anterior chamber lenses and transsclerally sutured posterior chamber lenses.

Intraocular pseudophakic correction during penetrating keratoplasty (PK) for aphakic or pseudophakic bullous keratopathy may be achieved either with anterior or posterior chamber lenses. Posterior chamber lenses can be fixed to the iris or sclera in eyes lacking adequate posterior capsular support. Post-PK astigmatism can delay early visual rehabilitation of the patient. We reviewed the last 15 patients at our institution who had undergone PK and anterior chamber lens placement for bullous keratopathy. These were compared to the last 15 patients who had undergone PK and transsclerally sutured posterior chamber lens placement. Patients who had placement of a flexible anterior chamber lens at time of PK had a mean astigmatism of 6.73 D at the last visit before any sutures were removed. There was no predominant axis of astigmatism or relationship of the axis of astigmatism to the meridian of lens placement. Patients with placement of a transsclerally sutured posterior chamber lens at time of PK had a mean astigmatism of 5.18 D at the last visit before any sutures were removed. Mean astigmatism was not significantly different (P greater than 0.05) from that seen with anterior chamber lens placement. In the majority of patients the axis of post-PK astigmatism was oriented perpendicular to the meridian of the transsclerally sutured posterior chamber lens.

Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study 4 years after surgery for myopia. Perk Study Group.

The Prospective Evaluation of Radial Keratotomy Study is a nine-center clinical trial of a surgical technique to reduce simple myopia by making incisions in the cornea. There were 435 patients (one eye per patient is reported) enrolled in the study with a 91% follow-up rate at 4 years after surgery. After surgery, uncorrected visual acuity was 20/40 or better in 76% of eyes. Fifty-five percent of the eyes had a refractive error within +/- 1.00 diopter; 28% were undercorrected, and 17% were overcorrected by more than 1.00 D. The width of the prediction 90% interval for the refractive change was 4.42 D, indicating a lack of predictability. The refractive error was not stable in some eyes; between 6 months and 4 years after surgery, 23% of eyes had a continued effect of the surgery of more than 1.00 D. For 323 patients with both eyes operated on, 64% stated they wore no optical correction. There were few serious complications. Eleven eyes (3%) lost two or three lines of best corrected visual acuity. Two eyes developed delayed bacterial keratitis without significant loss in best corrected visual acuity.