The combined (Genesis) technique of radial keratotomy. A prospective, multicenter study. Refractive Keratoplasty Study Group.

PURPOSE: A prospective, multicenter, clinical study to evaluate a standardized surgical (Genesis) protocol which includes combined-technique radial incisions in patients seeking reduction of their physiologic myopia. The combined incisions were designed to incorporate the safety of the centrifugal incision technique with the efficacy of the centripetal incision technique. METHODS: A total of 375 eyes undergoing radial keratotomy procedures performed in six different clinical centers were analyzed. All procedures were performed in accordance with the Genesis nomograms. The Genesis protocol called for using preoperative screening pachymetry to guide central clear zone size selection, incising the thinnest corneal quadrant first, suturing corneal perforations, and discouraged more than one enhancement procedure, when indicated. Globe fixation technique served as a study variable. RESULTS: Mean follow-up was 6.2 months (range, 1.5-12 months). Mean residual cycloplegic refraction was -0.48 +/- 0.61 diopters (D) (range, -2.50 to +1.50 D); 92% of eyes were within 1 D of the planned goal of -0.50 D and 85% were within 1 D of emmetropia; 14% were myopic; and 1% was hyperopic by more than 1 D. Uncorrected visual acuity was 20/40 or better in 95% of eyes; the remaining 5% retaining myopic refractive errors. A single procedure was performed in 73% of eyes, and 99% received less than two enhancements. Of eyes with no enhancements, 97% had uncorrected visual acuity of 20/40 or better. One study eye (0.3%) had a two-line loss of spectacle visual acuity. There were no invasions of the central clear zone. Globe fixation was a significant predictor for enhancement incidence (P < 0.001) but not for perforation incidence (P = 0.06). Incision sequence was predictive for perforation incidence (P < 0.0002). CONCLUSION: The combined-technique of radial keratotomy, coupled with the Genesis surgical protocol, affords centrifugal incision safety with centripetal incision efficacy. The Genesis nomograms, with a built in refractive outcome goal of -0.50 D provide an acceptable degree of accuracy and predictability while guarding against hyperopic overcorrection.

Effectiveness of histocompatibility matching in high-risk corneal transplantation: a summary of results from the Collaborative Corneal Transplantation Studies.

The Collaborative Corneal Transplantation Studies (CCTS) were designed to evaluate the effect of donor-recipient histocompatibility matching and crossmatching on the survival of corneal transplants in high-risk patients. Corneas were allocated to the 419 patients in the double-masked Antigen Matching Study on the basis of HLA-A,-B and HLA-DR antigen match. ABO blood group compatibility was determined but not used for recipient selection. The 37 patients in the Crossmatch Study were randomly assigned to receive a cornea from either a positively or negatively crossmatched donor. All patients received topical steroid therapy according to a standard protocol. Matching for HLA-A,-B and HLA-DR antigens had no effect on overall graft survival, the incidence of irreversible rejection, or the incidence of rejection episodes. The positive group in the Crossmatch Study had fewer graft failures, rejection failures, and rejection episodes than the negative group; however, these differences were not statistically significant. The estimated proportion of eyes with failure from rejection by 3 years was 30% for the ABO-incompatible group and 16% for the ABO-compatible group (relative risk, 1.98; 95% confidence interval, 1.15 to 3.13). These studies demonstrate that, for high-risk patients who are immunosuppressed by topical steroid therapy: 1) neither HLA-A.-B nor HLA-DR antigen matching substantially reduced the likelihood of corneal graft failure; 2) a positive donor-recipient crossmatch did not increase the risk of corneal graft failure; and 3) ABO blood group matching may be effective in reducing the risk of graft failure from rejection.

Temporary sutured tube-tarsorrhaphy: reversible eyelid closure technique.

Temporary closure of the eyelids is frequently recommended for ocular surface disorders in which reepithelialization of the cornea is problematic, as well as for acute Bell's palsy. We describe an easily performed technique of temporary tarsorrhaphy using plastic tubes sutured externally to the upper and lower eyelids, with eyelid closure accomplished by tightening a loop of suture passed through the two tubes. Corneal epithelial defects in 11 of 13 patients in whom we used this technique resolved satisfactorily without complications. In the remaining two, the polypropylene sutures eroded through the eyelids between 5 and 6 weeks after surgery. The sutured tubes loosened and the loosened sutures had to be replaced. In one patient, the overly long end of a suture rotated between the apposed eyelids, inducing a corneal abrasion, but no permanent damage to the eye. We conclude that the sutured tube-tarsorrhaphy provides excellent short-term closure of the eyelids, while allowing simple, painless opening for examining the globe. The risks of inflammation and infection associated with previously described techniques are minimized.

Etiology of corneal opacification in central Tanzania.

The frequency and causes of visually significant corneal opacification in central Tanzania was assessed by a population-based survey. The overall prevalence of bilateral corneal opacification was 1.16% (95% CI 0.31-1.44) and unilateral corneal opacification was 2.07% (95% CI 1.55-2.73). Bilateral corneal opacification was most frequently associated with trachoma, keratoconjunctivitis, vitamin A deficiency and measles. Unilateral corneal opacification had similar causes with the addition of cases caused by trauma. Corneal scarring is a frequent occurrence in this region. The majority of cases of corneal opacification are secondary to potentially preventable or treatable causes.

Effect of interferon on a primary conjunctival epithelial cell model of trachoma.

An in vitro human primary conjunctival epithelial system was adapted to determine if the effects of interferon-gamma (IFN-gamma), as described in cultured cell lines, were applicable to human ocular infection with Chlamydia trachomatis, Primary human epithelial cell cultures were exposed to varying concentrations of IFN-gamma. The treatment resulted in the induction of the tryptophan decyclizing enzyme indolamine 2,3-deoxygenase (IDO) in a dose-dependent manner as determined by assaying the conversion of tryptophan to its metabolites using reversed-phase high-performance liquid chromatography. Little IDO induction occurred in the presence of IFN-alpha or IFN-beta. Catabolism of up to 38% of available tryptophan occurred in IFN-gamma-treated cells in contrast to controls that showed only baseline activity. Cells cultured with IFN-gamma and then infected with an ocular isolate of C. trachomatis (TW-5), had a reduction in the percentage of inclusion-containing cells by over 80% in a dose-dependent manner. Reversal by the addition of exogenous tryptophan substantiated that IFN-gamma-mediated induction of IDO and catabolism of tryptophan were responsible for inhibition of intracellular growth of C. trachomatis.

Sacroiliac subluxation: a common, treatable cause of low-back pain in pregnancy.

A retrospective review of 100 consecutive pregnancies, involving 94 women receiving prenatal care at a rural western New York family practice, was conducted. Back pain was spontaneously reported to the physician by 23 women in 23 pregnancies. Eleven of the 23 women met diagnostic criteria for sacroiliac subluxation. These criteria include absence of lumbar spine and hip pathology, pain in the sacral region, a positive Piedallu's sign (asymmetrical movement of the posterior superior iliac spines upon forward flexion), a positive pelvic compression test, and asymmetry of the anterior superior iliac spines. A cohort of 11 women meeting criteria for sacroilia subluxation was treated with rotational manipulation of the sacroiliac joints. After manipulative therapy, 10 of the 11 women (91%) had relief of pain and no longer exhibited signs of sacroiliac subluxation.

Epidemiology of ocular chlamydial infection in a trachoma-hyperendemic area.

The epidemiology of ocular chlamydial infection in a trachoma-hyperendemic area of Tanzania was investigated. Specimens for chlamydial isolation cultures and direct fluorescent antibody cytology were collected from 1085 children aged 1-7 years. Other data included examinations for signs of clinical trachoma and the collection of household data on risk factors. A total of 33% of children had a positive laboratory test for Chlamydia species. The most important factors for predicting chlamydial infection were the presence of a sibling with laboratory evidence of infection, increased number of flies around the house, a household that herded cattle, and practice of a local religion. Younger children and girls were at no increased risk for a positive laboratory test, although these subgroups have more clinical disease. The data are compatible with a model of less frequent episodes of reinfection as children become older.

T cells and trachoma. Their role in cicatricial disease.

Frozen sections of tarsoconjunctival biopsies with trachomatous scarring from 14 black adults undergoing corrective surgery for trichiasis, and "normal" tissue from three postmortem controls, were immunohistochemically stained for the major T- and B-cell subsets, and for macrophages and monocytes. T cells outnumbered B cells by 2 to 17 times, and macrophages and monocytes by approximately 20 times in all specimens. Biopsies were categorized as "inflamed" if a cumulative inflammatory score of cellular staining in the substantia propria with CD4, CD8, and OKM1 monoclonal antibodies was greater than that of control tissues. CD4+ lymphocytes predominated over CD8+ lymphocytes in 5 of 7 inflamed biopsies, whereas CD8+ lymphocytes predominated over CD4+ lymphocytes in 5 of 7 noninflamed biopsies. Lymphoid aggregates were present in five inflamed biopsies, but lacked germinal centers, centrally located B cells, or parafollicular T cells typical of the acute stage of trachoma. CD4+ and CD8+ lymphocytes also were observed in the epithelium and lumen of Meibomian glands. These observations indicate that the inflammatory infiltrate of the tarsoconjunctiva in the cicatricial stage of trachoma is comprised predominantly of T cells, and suggests that T cells may be involved in the genesis of tarsal thickening and conjunctival scarring seen in the later stages of trachoma.

Prevalence and causes of vision loss in central Tanzania.

A population-based survey of the prevalence of major blinding disorders was conducted in three villages in central Tanzania. Overall, 1827 people over the age of seven years old were examined. In those age seven and older, the prevalence of bilateral blindness (visual acuity in the better eye of less than 3/60) was 1.26% and monocular blindness (visual acuity of less than 3/60 in one eye) was 4.32% and the prevalence of visual impairment (visual acuity less than 6/18 but greater than or equal to 3/60 in both eyes was 1.04% and in one eye was 1.75%. Corneal opacities were responsible for 44% of bilateral and 39% of monocular blindness and resulted from trachoma, measles often in association with Vitamin A deficiency, keratoconjunctivitis, and the use of traditional eye medicines. Cataracts accounted for 22% of bilateral and 6% of monocular blindness. Readily preventable or reversible causes of blindness were responsible for 65% of cases of bilateral and 46% of monocular blindness.

A systematic approach to the diagnosis and treatment of chronic conjunctivitis.

In 58 patients with chronic conjunctivitis of greater than two weeks' duration, examination included obtaining an ocular and general medical history and performing a complete ophthalmic examination of the external eye. Conjunctival smears were obtained for Gram and Giemsa staining, direct immunofluorescent monoclonal antibody staining for Chlamydia trachomatis and herpes simplex virus, and chlamydial culture. Cultures for bacteria and viruses were obtained in 33 patients. The cause of the chronic conjunctivitis based on clinical and laboratory criteria was established in 40 of 58 (69%) patients: chlamydia, 11 (19%); virus, eight (14%); irritant, six (10%); allergen, four (7%); contact lens, four (7%); bacteria, four (7%); acne rosacea, two (3%); and floppy eyelid syndrome, one (2%). In 18 of 58 (31%) patients, no specific cause was detected. We recommend a systematic approach in the investigation of chronic conjunctivitis. Direct immunofluorescent monoclonal antibody staining is an effective and rapid technique for detecting chronic chlamydial conjunctivitis.

Hygiene factors and increased risk of trachoma in central Tanzania.

Trachoma remains the major infectious cause of blindness in many developing areas, especially where hygiene is poor. The practices and behaviors associated with an increased risk of trachoma were studied in central Tanzania, where a stratified random cluster sample of 8409 people was examined. Data were collected on family and individual characteristics and behaviors and on trachoma status. Overall, 60% of the children aged 1 to 7 years had active inflammatory trachoma, and 10% of those aged 60 years or older had trichiasis. Regression analysis showed that active inflammatory trachoma in children was associated with the characteristics of the more traditional families and several measures of poor personal hygiene. Two important risk factors for severe inflammatory trachoma were poor facial cleanliness in children (odds ratio of 1.7 [1.17, 2.50]) and household fly density (odds ratio of 1.63 [1.17, 2.29]). Both factors are potentially amenable to intervention. These data suggest that an intervention strategy aimed at these hygiene measures would provide an effective method of controlling trachoma in this region, and a similar approach may be useful in other areas.

The epidemiology of infection in trachoma.

Specimens for chlamydial isolation culture and direct fluorescent antibody cytology (DFA) were collected from 1671 women and children from a trachoma-endemic area in Central Tanzania. Trachoma was graded using the new World Health Organization grading scheme, and 54% of the children and 9% of the women had inflammatory trachoma (TF or TI). DFA, using the presence of five elementary bodies as the criterion for a positive test, had a sensitivity of 88.0% and a specificity of 87.5% compared to culture and a sensitivity of 54.7% and specificity of 92.8% compared to clinical diagnosis. Altogether, 52.9% of those with trachoma grade TF were positive on either or both culture and DFA versus 77.0% of those with TI. Twenty-nine isolates were serotyped; 18 were serovar A, ten were serovar B, and one was serovar Ba. Positive cultures or DFA were obtained in 6.9% of those graded clinically as not having TF or TI and in a smaller number of those without any perceptible evidence of disease. Conversely, organisms could not be demonstrated in a number of people with severe inflammation (TI) even though some became positive after multiple repeated culture. These two findings of infection without disease and disease without evidence of infection suggest the importance of the immunologic response to infection in determining the clinical status. DFA was found to be an appropriate test for future field studies of trachoma. Further studies of those with disease but without agent and of those with agent but without disease will help understand the dynamics of infection and transmission and the role of the immune response in this important blinding disease.

Epidemiology and diagnosis of acute conjunctivitis at an inner-city hospital.

Chlamydia has been found to be the cause of a high percentage of cases of neonatal and chronic conjunctivitis in an inner-city population. To assess the etiology and epidemiology of acute conjunctivitis in this population, conjunctival scrapings were sampled from 45 patients presenting to an ocular emergency room; and replicate chlamydial, viral, and bacterial cultures and cytology tests were done. No cases of chlamydial conjunctivitis were diagnosed, although a viral etiology was established in 36% of the cases and a bacterial etiology in 40%. Twenty-four percent of the cases were not diagnosed. The authors recommend limiting the initial laboratory workup of patients with acute conjunctivitis to obtaining conjunctival smears for Gram and Giemsa staining. Chlamydial direct immunofluorescent monoclonal antibody (DFA) should be done if the patient is sexually active. Hyperacute conjunctivitis or acute conjunctivitis refractory to treatment mandates a more complete set of laboratory tests.

Water availability and trachoma.

As part of an epidemiological survey of risk factors for trachoma in 20 villages in the United Republic of Tanzania, we investigated the relationship of village water pumps, distance to water source, and quantity of household water to the risk of inflammatory trachoma. We also evaluated whether there was an association between the cleanliness of children's faces and these water variables. No association was found between the presence of a village water supply and the prevalence of trachoma. However, the risk of trachoma in the household increased with the distance to a water source--although there was no association with the estimated daily amount of water brought into the house. Likewise, children were more likely to have unclean faces if they lived more than 30 minutes from a water source, but whether they had clean faces was not associated with the daily quantity of water brought into the household. The effect of the distance to water supply on trachoma may well reflect the value placed on water within the family, and this determines the priority for its use for hygiene purposes. The results of the study suggest that changing the access to water per se may be insufficient to alter the prevalence of trachoma without also a concomitant effort to change the perception of how water should be utilized in the home.

Ophthalmology consultations at a large teaching hospital.

We reviewed 100 consecutive ophthalmology consultations performed on inpatients at a large teaching hospital to help identify areas that may require greater emphasis in the medical school and housestaff curriculum. Nonophthalmologists rarely record visual acuities or perform dilated fundus examinations. If visual acuity determination were more consistently made a part of routine physical examinations, it is possible that more pathology would be detected and non-productive consultations could be minimized. We plan to emphasize these observations in our school's curriculum more than in the past.