H. Dwight Cavanagh

Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study One Year After Surgery

The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within +/- 1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, -4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between -2.00 and -4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by greater than 0.50 diopters in 19% of eyes.

Penetrating Keratoplasty in Children

Retrospectively studied were 91 patients, 14 years of age or less, who had 152 penetrating keratoplasties in 107 eyes, with an average follow-up of 30.1 months. Survival analysis showed the probability of obtaining a clear graft at one year to be 60 +/- 8% in 45 eyes with congenital opacities, 70 +/- 8% in 31 eyes with opacities from trauma and 73 +/- 8% in 31 eyes with acquired nontraumatic opacities. Most failures occurred during the first postoperative year and were characterized by the gradual loss of graft clarity from undetermined cause. Twenty-nine percent (10) of the 34 eyes with congenital corneal opacities in which vision could be measured had a most recent visual acuity better than 6/120 (20/400). Irreversible amblyopia, glaucoma, other structural abnormalities of the anterior segment and mental retardation complicated visual rehabilitation in the congenital group. In the post-traumatic group, vision was better than 6/120 (20/400) in 45% (13) of 29 eyes, being limited by vitreoretinal pathology, fibrous ingrowth, and optic nerve damage from glaucoma. Visual acuity in the acquired, nontraumatic group was better than 6/120 (20/400) in 67% (20) of 30 eyes. The percentage of patients achieving 6/12 (20/40) or better in the congenital, post-traumatic, and nontraumatic groups were 3% (1/34), 17% (5/29), and 47% (14/30), respectively. In the congenital group, only patients with posterior polymorphous dystrophy obtained a visual acuity of 6/30 (20/100) or better. Preoperative vascularization of the cornea, persistent epithelial defects, and performance of lensectomy-vitrectomy were factors most highly correlated with poor graft survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Endophthalmitis Following Penetrating Keratoplasty

To determine the incidence of infectious endophthalmitis in the early postoperative period following penetrating keratoplasty, and the type and origin of the causative organisms, all cases of penetrating keratoplasty performed at the Emory University affiliated hospitals between January 1977 and March 1982 were reviewed. Four (0.2%) of the 1,876 cases developed infectious endophthalmitis. In all four, evidence of infection developed within 72 hours, and in three the donor rim culture grew the same organism as was obtained from the anterior chamber or vitreous. The causative organisms were Streptococcus pneumoniae, Staphylococcus aureus, group D Streptococcus-enterococcus, and Pseudomonas aeruginosa. Eyes with positive donor rim cultures had a 22-fold increased incidence of endophthalmitis.

Microbial keratitis pathogens and antibiotic susceptibilities: a 5-year review of cases at an urban county hospital in north Texas.

Purpose.To review the epidemiology, risk factors, microbiologic spectrum, and outcomes of microbial keratitis and to compare cases in which a causative organism is identified to those determined to be sterile during a 5-year period at a large county hospital in north Texas. Methods.A retrospective chart review of cases of microbial keratitis at Parkland Memorial Hospital between January 2000 and December 2004. Results.During this 5-year period, 132 eyes of 131 patients underwent 139 corneal scrapings for presumed microbial keratitis and an organism was reported in 73 (52.5%) cultures. Including abnormal confocal microscopy results, a causative organism was determined in 78 (56.1%) cases. At least one risk factor was present in 115 (87.1%) cases, with the most common risk factors being preexisting ocular disease, contact lens wear, and a history of trauma. Nearly 5% of patients reported a history of cocaine use. Gram staining correctly identified the organism in 20 (28.6%) culture-positive cases, and Pseudomonas aeruginosa was the most common isolate, followed by Staphylococcus aureus. The rate of S. aureus resistance to fluoroquinolones (15.4%) was similar to rates previously reported from the early to mid 1990s, but less than those reported from the late 1990s. Severe complications were more common in the nonsterile subgroup (34.2%) than in the sterile (16.9%) subgroup (P=0.041). Although the rate of acute intervention was higher in the nonsterile subgroup (27.4%) than in the sterile subgroup (20.3%), this difference was not statistically significant (P=0.461). Mean logMAR visual acuity was 1.451 (Snellen equivalent, 20/563) at presentation and 1.062 (20/231) at the last follow-up visit (P<0.001). Presenting and final visual acuities were significantly better in the sterile subgroup than in the nonsterile subgroup (P<0.001 and P=0.002, respectively). Conclusions.When a causative organism is not identified in microbial keratitis, visual acuity is not as severely affected, and fewer severe complications occur. Antibiotic resistance to fluoroquinolones and aminoglycosides, though not common, still deserves consideration in the treatment of microbial keratitis.

Induced ocular pseudopemphigoid

Two patients with a clinical picture identical to idiopathic ocular cicatricial pemphigoid had received long-term (six to nine years) echothiophate iodide treatment for control of glaucoma in the affected eyes after cataract extraction. Basement membrane zone staining for IgG was seen in the conjunctiva of one affected eye. Decreased or absent goblet cells, epidermalization of the conjunctiva, fibroses, and abnormal numbers of inflammatory cells were seen in both affected eyes.

Tear IgA and serum IgG antibodies against Acanthamoeba in patients with Acanthamoeba keratitis.

Purpose. Exposure to Acanthamoeba species appears to be ubiquitous, as 50% to 100% of healthy human subjects display anti-Acanthamoeba antibodies. However, the presence of specific anti-Acanthamoeba antibodies in the serum and tears of patients has not been investigated. The prevalence of serum immunoglobulin G (IgG) and tear IgA against three species of Acanthamoeba was assessed in healthy subjects and patients with Acanthamoeba keratitis. Methods. The level of specific serum IgG and tear IgA against A. castellanii, A. astronyxis, and A. culbertsoni in the sera of 23 patients and 25 healthy subjects was tested by enzyme-linked immunosorbent assays. Total serum IgM, IgG, and IgA concentrations were measured by nephelometry. Acanthamoeba keratitis was diagnosed clinically and confirmed by in vivo confocal microscopy. In some patients, corneal biopsies were also performed and trophozoites were cultured on lawns of Escherichia coli on non-nutrient agar. Results. All healthy subjects and patients with Acanthamoeba keratitis had detectable serum IgG antibodies against all Acanthamoeba antigens. However, patients with Acanthamoeba keratitis had significantly higher anti-Acanthamoeba IgG antibody titers than healthy subjects. In contrast, Acanthamoeba-specific tear IgA was significantly lower in patients with Acanthamoeba keratitis in comparison with healthy subjects. Total serum immunoglobulins did not differ significantly between healthy subjects and patients with Acanthamoeba keratitis. Conclusions. The results suggest that a low level of anti-Acanthamoeba IgA antibody in the tears appears to be associated with Acanthamoeba keratitis.

Results of Penetrating Keratoplasty in 123 Eyes with Pseudophakic or Aphakic Corneal Edema

The clinical records of 123 eyes that received a penetrating keratoplasty for aphakic or pseudophakic corneal edema with a mean follow-up time of 18 months were studied retrospectively. Thirty-five eyes from which an intraocular lens (IOL--85% iris fixated) was removed at the time of keratoplasty were compared with 88 eyes that never had an IOL. The mean interval between initial cataract surgery and penetrating keratoplasty was 28 months for the pseudophakic group from which the IOL was removed and 67 months for the aphakic group without IOL. In both groups, 97% had an anterior vitrectomy. Corneal grafts remained clear in 91% of the previously pseudophakic eyes and in 81% of the aphakic eyes (P less than or equal to 0.05). The final corrected visual acuity was worse in the pseudophakic eyes with IOL removed (16% saw 6/6 to 6/12 while 22% saw worse than 6/60) than in the aphakic eyes (34% saw 6/6 to 6/12 while 7% saw worse than 6/60). Postoperative maculopathy occurred in 43% of eyes from which IOLs were removed and in 22% of aphakic eyes.

A cluster of cases of Mycobacterium chelonei keratitis associated with outpatient office procedures.

We studied three cases of keratitis caused by Mycobacterium chelonei, a nontuberculous mycobacterial species. The cases occurred in two women, 76 and 80 years old, and one man, 67 years old, treated as outpatients in the same office. One case followed suture removal and the other two occurred after posterior capsulotomy. Corneal lesions appeared within two to three weeks of trauma and were white, round infiltrates with indistinct margins and radiating projections. The lesions were found at all levels of the stroma and were associated with an epithelial defect. Anterior chamber reaction varied from a minimal response to a hypopyon. One patient responded to topical therapy with amikacin and erythromycin, but the other two patients required penetrating keratoplasties because of deep abscesses, which progressed toward the sclera despite therapy. These cases emphasized the possibility of rapidly growing nontuberculous mycobacteria producing serious ocular infections.

Effect of Donor Epithelium on Corneal Transplant Survival

Two hundred thirty-two penetrating keratoplasties in 228 eyes were performed with or without the removal of donor corneal epithelium in a prospective, randomized clinical trial to determine the effect of epithelial removal on graft survival. The removal of epithelium did not reduce the likelihood of graft failure, irreversible allograft reaction, or reversible allograft reaction.

Effect of Bilateral and Unilateral Grafts on the Incidence of Rejections in Keratoconus

We studied results of 124 keratoplasties in 100 keratoconus patients; 61 men and 39 women varying in ages from 11 to 69 years with an average age of 30 years. Twenty-four patients had bilateral grafts with a 27% incidence of rejection, and 76 patients had unilateral grafts with a 13% incidence of rejection (P less than .01). Data analysis of the first year after the graft of first eyes and subsequent years after the graft of first and second eyes, however, revealed a nearly fourfold increase of rejections following second grafts, with a 17% increased chance of rejection for the first graft after the second was implanted. Only two of the bilateral and two of the unilateral grafts were irreversibly lost because of graft reaction. The major complication was the formation of posterior subcapsular cataract, which occurred in approximately 32% of the patients. The final postkeratoplasty visual acuities were significantly improved. In the patients who did not develop a cataract, 86% achieved visual acuity of 6/12 (20/40) or better. In the patients who did develop cataracts, 68% achieved visual acuity of 6/12 (20/40) or better.